Tag Archives: Fly

Eevee mugshot set for Doom

Post Syndicated from Eevee original https://eev.ee/release/2017/11/23/eevee-mugshot-set-for-doom/

Screenshot of Industrial Zone from Doom II, with an Eevee face replacing the usual Doom marine in the status bar

A full replacement of Doomguy’s vast array of 42 expressions.

You can get it yourself if you want to play Doom as me, for some reason? It does nothing but replace a few sprites, so it works with any Doom flavor (including vanilla) on 1, 2, or Final. Just run Doom with -file eeveemug.wad. With GZDoom, you can load it automatically.


I don’t entirely know why I did this. I drew the first one on a whim, then realized there was nothing really stopping me from making a full set, so I spent a day doing that.

The funny thing is that I usually play Doom with ZDoom’s “alternate” HUD. It’s a full-screen overlay rather than a huge bar, and — crucially — it does not show the mugshot. It can’t even be configured to show the mugshot. As far as I’m aware, it can’t even be modded to show the mugshot. So I have to play with the OG status bar if I want to actually use the thing I made.

Preview of the Eevee mugshot sprites arranged in a grid, where the Eevee becomes more beaten up in each subsequent column

I’m pretty happy with the results overall! I think I did a decent job emulating the Doom “surreal grit” style. I did the shading with Aseprite‘s shading mode — instead of laying down a solid color, it shifts pixels along a ramp of colors you select every time you draw over them. Doom’s palette has a lot of browns, so I made a ramp out of all of them and kept going over furry areas, nudging pixels into being lighter or darker, until I liked the texture. It was a lot like making a texture in a sketch with a lot of scratchy pencil strokes.

I also gleaned some interesting things about smoothness and how the eye interprets contours? I tried to explain this on Twitter and had a hell of a time putting it into words, but the short version is that it’s amazing to see the difference a single misplaced pixel can make, especially as you slide that pixel between dark and light.


Doom's palette of 256 colors, many of which are very long gradients of reds and browns

Speaking of which, Doom’s palette is incredibly weird to work with. Thank goodness Eevees are brown! The game does have to draw arbitrary levels of darkness all with the same palette, which partly explains the number of dark colors and gradients — but I believe a number of the colors are exact duplicates, so close they might as well be duplicates, or completely unused in stock Doom assets. I guess they had no reason to optimize for people trying to add arbitrary art to the game 25 years later, though. (And nowadays, GZDoom includes a truecolor software renderer, so the palette is becoming less and less important.)

I originally wanted the god mode sprite to be a Sylveon, but Sylveon is made of pink and azure and blurple, and I don’t think I could’ve pulled it off with this set of colors. I even struggled with the color of the mane a bit — I usually color it with pretty pale colors, but Doom only has a couple of those, and they’re very saturated. I ended up using a lot more dark yellows than I would normally, and thankfully it worked out pretty well.

The most significant change I made between the original sprite and the final set was the eye color:

A comparison between an original Doom mugshot sprite, the first sprite I drew, and how it ended up

(This is STFST20, a frame from the default three-frame “glacing around” animation that plays when the player has between 40 and 59 health. Doom Wiki has a whole article on the mugshot if you’re interested.)

The blue eyes in my original just do not work at all. The Doom palette doesn’t have a lot of subtle colors, and its blues in particular are incredibly bad. In the end, I made the eyes basically black, though with a couple pixels of very dark blue in them.

After I decided to make the full set, I started by making a neutral and completely healthy front pose, then derived the others from that (with a very complicated system of layers). You can see some of the side effects of that here: the face doesn’t actually turn when glancing around, because hoo boy that would’ve been a lot of work, and so the cheek fluff is visible on both sides.

I also notice that there are two columns of identical pixels in each eye! I fixed that in the glance to the right, but must’ve forgotten about it here. Oh, well; I didn’t even notice until I zoomed in just now.

A general comparison between the Doom mugshots and my Eevee ones, showing each pose in its healthy state plus the neutral pose in every state of deterioration

The original sprites might not be quite aligned correctly in the above image. The available space in the status bar is 35×31, of which a couple pixels go to an inset border, leaving 33×30. I drew all of my sprites at that size, but the originals are all cropped and have varying offsets (part of the Doom sprite format). I extremely can’t be assed to check all of those offsets for over a dozen sprites, so I just told ImageMagick to center them. (I only notice right now that some of the original sprites are even a full 31 pixels tall and draw over the top border that I was so careful to stay out of!)

Anyway, this is a representative sample of the Doom mugshot poses.

The top row shows all eight frames at full health. The first three are the “idle” state, drawn when nothing else is going on; the sprite usually faces forwards, but glances around every so often at random. The forward-facing sprite is the one I finalized first.

I tried to take a lot of cues from the original sprite, seeing as I wanted to match the style. I’d never tried drawing a sprite with a large palette and a small resolution before, and the first thing that struck me was Doomguy’s lips — the upper lip, lips themselves, and shadow under the lower lip are all created with only one row of pixels each. I thought that was amazing. Now I even kinda wish I’d exaggerated that effect a bit more, but I was wary of going too dark when there’s a shadow only a couple pixels away. I suppose Doomguy has the advantage of having, ah, a chin.

I did much the same for the eyebrows, which was especially necessary because Doomguy has more of a forehead than my Eevee does. I probably could’ve exaggerated those a bit more, as well! Still, I love how they came out — especially in the simple looking-around frames, where even a two-pixel eyebrow raise is almost comically smug.

The fourth frame is a wild-ass grin (even named STFEVL0), which shows for a short time after picking up a new weapon. Come to think of it, that’s a pretty rare occurrence when playing straight through one of the Doom games; you keep your weapons between levels.

The fifth through seventh are also a set. If the player takes damage, the status bar will briefly show one of these frames to indicate where the damage is coming from. You may notice that where Doomguy bravely faces the source of the pain, I drew myself wincing and recoiling away from it.

The middle frame of that set also appears while the player is firing continuously (regardless of damage), so I couldn’t really make it match the left and right ones. I like the result anyway. It was also great fun figuring out the expressions with the mouth — that’s another place where individual pixels make a huge difference.

Finally, the eighth column is the legendary “ouch” face, which appears when the player takes more than 20 damage at once. It may look completely alien to you, because vanilla Doom has a bug that only shows this face when the player gains 20 or more health while taking damage. This is vanishingly rare (though possible!), so the frame virtually never appears in vanilla Doom. Lots of source ports have fixed this bug, making the ouch face it a bit better known, but I usually play without the mugshot visible so it still looks super weird to me. I think my own spin on it is a bit less, ah, body horror?

The second row shows deterioration. It is pretty weird drawing yourself getting beaten up.

A lot of Doomguy’s deterioration is in the form of blood dripping from under his hair, which I didn’t think would translate terribly well to a character without hair. Instead, I went a little cartoony with it, adding bandages here and there. I had a little bit of a hard time with the bloodshot eyes at this resolution, which I realize as I type it is a very poor excuse when I had eyes three times bigger than Doomguy’s. I do love the drooping ears, with the possible exception of the fifth state, which I’m not sure is how that would actually look…? Oh well. I also like the bow becoming gradually unravelled, eventually falling off entirely when you die.

Oh, yes, the sixth frame there (before the gap) is actually for a dead player. Doomguy’s bleeding becomes markedly more extreme here, but again that didn’t really work for me, so I went a little sillier with it. A little. It’s still pretty weird drawing yourself dead.

That leaves only god mode, which is incredible. I love that glow. I love the faux whisker shapes it makes. I love how it fades into the background. I love that 100% pure “oh this is pretty good” smile. It all makes me want to just play Doom in god mode forever.

Now that I’ve looked closely at these sprites again, I spy a good half dozen little inconsistencies and nitpicks, which I’m going to refrain from spelling out. I did do this in only a day, and I think it came out pretty dang well considering.

Maybe I’ll try something else like this in the future. Not quite sure what, though; there aren’t many small and self-contained sets of sprites like this in Doom. Monsters are several times bigger and have a zillion different angles. Maybe some pickups, which only have one frame?


Hmm. Parting thought: I’m not quite sure where I should host this sort of one-off thing. It arguably belongs on Itch, but seems really out of place alongside entire released games. It also arguably belongs on the idgames archive, but I’m hesitant to put it there because it’s such an obscure thing of little interest to a general audience. At the moment it’s just a file I’ve uploaded to wherever on my own space, but I now have three little Doom experiments with no real permanent home.

[$] ROCA: Return Of the Coppersmith Attack

Post Syndicated from jake original https://lwn.net/Articles/738896/rss

On October 30, 2017, a group
of Czech researchers from Masaryk University presented the ROCA paper
at the ACM CCS Conference, which earned
the Real-World Impact
Award
. We briefly mentioned ROCA when
it was first reported
but haven’t dug into details of the vulnerability yet. Because of its
far-ranging impact, it seems important to review the vulnerability in
light of the new results published recently.

New Research in Invisible Inks

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2017/11/new_research_in.html

It’s a lot more chemistry than I understand:

Invisible inks based on “smart” fluorescent materials have been shining brightly (if only you could see them) in the data-encryption/decryption arena lately…. But some of the materials are costly or difficult to prepare, and many of these inks remain somewhat visible when illuminated with ambient or ultraviolet light. Liang Li and coworkers at Shanghai Jiao Tong University may have come up with a way to get around those problems. The team prepared a colorless solution of an inexpensive lead-based metal-organic framework (MOF) compound and used it in an ink-jet printer to create completely invisible patterns on paper. Then they exposed the paper to a methylammonium bromide decryption solution…revealing the pattern…. They rendered the pattern invisible again by briefly treating the paper with a polar solvent….

Full paper.

B2 Cloud Storage Roundup

Post Syndicated from Andy Klein original https://www.backblaze.com/blog/b2-cloud-storage-roundup/

B2 Integrations
Over the past several months, B2 Cloud Storage has continued to grow like we planted magic beans. During that time we have added a B2 Java SDK, and certified integrations with GoodSync, Arq, Panic, UpdraftPlus, Morro Data, QNAP, Archiware, Restic, and more. In addition, B2 customers like Panna Cooking, Sermon Audio, and Fellowship Church are happy they chose B2 as their cloud storage provider. If any of that sounds interesting, read on.

The B2 Java SDK

While the Backblaze B2 API is well documented and straight-forward to implement, we were asked by a few of our Integration Partners if we had an SDK they could use. So we developed one as an open-course project on GitHub, where we hope interested parties will not only use our Java SDK, but make it better for everyone else.

There are different reasons one might use the Java SDK, but a couple of areas where the SDK can simplify the coding process are:

Expiring Authorization — B2 requires an application key for a given account be reissued once a day when using the API. If the application key expires while you are in the middle of transferring files or some other B2 activity (bucket list, etc.), the SDK can be used to detect and then update the application key on the fly. Your B2 related activities will continue without incident and without having to capture and code your own exception case.

Error Handling — There are different types of error codes B2 will return, from expired application keys to detecting malformed requests to command time-outs. The SDK can dramatically simplify the coding needed to capture and account for the various things that can happen.

While Backblaze has created the Java SDK, developers in the GitHub community have also created other SDKs for B2, for example, for PHP (https://github.com/cwhite92/b2-sdk-php,) and Go (https://github.com/kurin/blazer.) Let us know in the comments about other SDKs you’d like to see or perhaps start your own GitHub project. We will publish any updates in our next B2 roundup.

What You Can Do with Affordable and Available Cloud Storage

You’re probably aware that B2 is up to 75% less expensive than other similar cloud storage services like Amazon S3 and Microsoft Azure. Businesses and organizations are finding that projects that previously weren’t economically feasible with other Cloud Storage services are now not only possible, but a reality with B2. Here are a few recent examples:

SermonAudio logo SermonAudio wanted their media files to be readily available, but didn’t want to build and manage their own internal storage farm. Until B2, cloud storage was just too expensive to use. Now they use B2 to store their audio and video files, and also as the primary source of downloads and streaming requests from their subscribers.
Fellowship Church logo Fellowship Church wanted to escape from the ever increasing amount of time they were spending saving their data to their LTO-based system. Using B2 saved countless hours of personnel time versus LTO, fit easily into their video processing workflow, and provided instant access at any time to their media library.
Panna logo Panna Cooking replaced their closet full of archive hard drives with a cost-efficient hybrid-storage solution combining 45Drives and Backblaze B2 Cloud Storage. Archived media files that used to take hours to locate are now readily available regardless of whether they reside in local storage or in the B2 Cloud.

B2 Integrations

Leading companies in backup, archive, and sync continue to add B2 Cloud Storage as a storage destination for their customers. These companies realize that by offering B2 as an option, they can dramatically lower the total cost of ownership for their customers — and that’s always a good thing.

If your favorite application is not integrated to B2, you can do something about it. One integration partner told us they received over 200 customer requests for a B2 integration. The partner got the message and the integration is currently in beta test.

Below are some of the partner integrations completed in the past few months. You can check the B2 Partner Integrations page for a complete list.

Archiware — Both P5 Archive and P5 Backup can now store data in the B2 Cloud making your offsite media files readily available while keeping your off-site storage costs predictable and affordable.

Arq — Combine Arq and B2 for amazingly affordable backup of external drives, network drives, NAS devices, Windows PCs, Windows Servers, and Macs to the cloud.

GoodSync — Automatically synchronize and back up all your photos, music, email, and other important files between all your desktops, laptops, servers, external drives, and sync, or back up to B2 Cloud Storage for off-site storage.

QNAP — QNAP Hybrid Backup Sync consolidates backup, restoration, and synchronization functions into a single QTS application to easily transfer your data to local, remote, and cloud storage.

Morro Data — Their CloudNAS solution stores files in the cloud, caches them locally as needed, and syncs files globally among other CloudNAS systems in an organization.

Restic – Restic is a fast, secure, multi-platform command line backup program. Files are uploaded to a B2 bucket as de-duplicated, encrypted chunks. Each backup is a snapshot of only the data that has changed, making restores of a specific date or time easy.

Transmit 5 by Panic — Transmit 5, the gold standard for macOS file transfer apps, now supports B2. Upload, download, and manage files on tons of servers with an easy, familiar, and powerful UI.

UpdraftPlus — WordPress developers and admins can now use the UpdraftPlus Premium WordPress plugin to affordably back up their data to the B2 Cloud.

Getting Started with B2 Cloud Storage

If you’re using B2 today, thank you. If you’d like to try B2, but don’t know where to start, here’s a guide to getting started with the B2 Web Interface — no programming or scripting is required. You get 10 gigabytes of free storage and 1 gigabyte a day in free downloads. Give it a try.

The post B2 Cloud Storage Roundup appeared first on Backblaze Blog | Cloud Storage & Cloud Backup.

Hollywood Keeps Screener Piracy ‘Alive’ by Mailing 70,000 Discs a Year

Post Syndicated from Ernesto original https://torrentfreak.com/hollywood-keeps-screener-piracy-alive-by-mailing-70000-discs-a-year-171102/

At the end of the year movie industry insiders traditionally receive their screener copies, which they use to vote on the Oscars and other awards.

As is tradition, quite a few of these advance screeners will leak on various pirate sites. Last year the action started late, but eventually more than a dozen copies found their way to pirate sites.

The problem is not minor. Over the past fifteen years, screener copies of more than half of all the Oscar-nominated films have leaked online. Many of them appeared while the movies were still playing in theaters, or even before.

Hollywood has been working hard to contain the problem with watermarks and other security protocols but it seems hard to contain. This isn’t really a surprise when you look at the numbers. According to reports, studios send out 70,000 physical discs every year.

“No matter how much you try to secure your product, if you’re sending out a movie, it will leak online,” an anonymous source at a top awards screeners distributor told Variety, which reported on the issue.

In recent years several new online screening options have been developed. These are much cheaper, less than $4 compared to up to $35 for a watermarked physical disc. On top of that, they’re also much more secure and less likely to be stolen or copied in the distribution process.

Interestingly, however, many studios are reluctant to make this change. Not because they are worried about the technology itself, which works just fine, but because they fear that older voters are not tech savvy enough to handle an online screener.

This is corroborated by Matt Suggs, the executive VP of the online screening platform Mediafly. “The No. 1 concern is the older awards-voter demographic. This is brought up by every one of our customers,” he says.

Apparently, awards votes are more important than security in this instance. This is good news for pirates who have a better chance of seeing advance screener copies leak because of it. The question is, how long will this last?

Technology advances at a rapid pace. Just ten years ago it was pretty much impossible to stream a Hollywood movie online, something that everyone takes for granted today. So, eventually, screeners will all move to the Internet as well.

Suggs compares it to the shift from VHS to DVDs. At first, many older voters were not happy with the change, but eventually, everyone caved in.

“The same concerns existed when the studios moved to DVDs. For several years, they still had older members asking for VHS tapes. It’s just inevitable that they’re going to migrate to eScreeners in the same way. The real solution to this problem is time,” he says.

That said, even when all screeners move to a well-protected online platforms, leaks will still be possible. After all, pirates and hackers tend to be very familiar with the online playground.

Source: TF, for the latest info on copyright, file-sharing, torrent sites and ANONYMOUS VPN services.

DragonFly BSD 5.0

Post Syndicated from ris original https://lwn.net/Articles/736559/rss

DragonFly BSD 5.0 has been released. “Preliminary HAMMER2 support has been released into the wild as-of the 5.0 release. This support is considered EXPERIMENTAL and should generally not yet be used for production machines and important data. The boot loader will support both UFS and HAMMER2 /boot. The installer will still use a UFS /boot even for a HAMMER2 installation because the /boot partition is typically very small and HAMMER2, like HAMMER1, does not instantly free space when files are deleted or replaced.

DragonFly 5.0 has single-image HAMMER2 support, with live dedup (for cp’s), compression, fast recovery, snapshot, and boot support. HAMMER2 does not yet support multi-volume or clustering, though commands for it exist. Please use non-clustered single images for now.”

Coaxing 2D platforming out of Unity

Post Syndicated from Eevee original https://eev.ee/blog/2017/10/13/coaxing-2d-platforming-out-of-unity/

An anonymous donor asked a question that I can’t even begin to figure out how to answer, but they also said anything else is fine, so here’s anything else.

I’ve been avoiding writing about game physics, since I want to save it for ✨ the book I’m writing ✨, but that book will almost certainly not touch on Unity. Here, then, is a brief run through some of the brick walls I ran into while trying to convince Unity to do 2D platforming.

This is fairly high-level — there are no blocks of code or helpful diagrams. I’m just getting this out of my head because it’s interesting. If you want more gritty details, I guess you’ll have to wait for ✨ the book ✨.

The setup

I hadn’t used Unity before. I hadn’t even used a “real” physics engine before. My games so far have mostly used LÖVE, a Lua-based engine. LÖVE includes box2d bindings, but for various reasons (not all of them good), I opted to avoid them and instead write my own physics completely from scratch. (How, you ask? ✨ Book ✨!)

I was invited to work on a Unity project, Chaos Composer, that someone else had already started. It had basic movement already implemented; I taught myself Unity’s physics system by hacking on it. It’s entirely possible that none of this is actually the best way to do anything, since I was really trying to reproduce my own homegrown stuff in Unity, but it’s the best I’ve managed to come up with.

Two recurring snags were that you can’t ask Unity to do multiple physics updates in a row, and sometimes getting the information I wanted was difficult. Working with my own code spoiled me a little, since I could invoke it at any time and ask it anything I wanted; Unity, on the other hand, is someone else’s black box with a rigid interface on top.

Also, wow, Googling for a lot of this was not quite as helpful as expected. A lot of what’s out there is just the first thing that works, and often that’s pretty hacky and imposes severe limits on the game design (e.g., “this won’t work with slopes”). Basic movement and collision are the first thing you do, which seems to me like the worst time to be locking yourself out of a lot of design options. I tried very (very, very, very) hard to minimize those kinds of constraints.

Problem 1: Movement

When I showed up, movement was already working. Problem solved!

Like any good programmer, I immediately set out to un-solve it. Given a “real” physics engine like Unity prominently features, you have two options: ⓐ treat the player as a physics object, or ⓑ don’t. The existing code went with option ⓑ, like I’d done myself with LÖVE, and like I’d seen countless people advise. Using a physics sim makes for bad platforming.

But… why? I believed it, but I couldn’t concretely defend it. I had to know for myself. So I started a blank project, drew some physics boxes, and wrote a dozen-line player controller.

Ah! Immediate enlightenment.

If the player was sliding down a wall, and I tried to move them into the wall, they would simply freeze in midair until I let go of the movement key. The trouble is that the physics sim works in terms of forces — moving the player involves giving them a nudge in some direction, like a giant invisible hand pushing them around the level. Surprise! If you press a real object against a real wall with your real hand, you’ll see the same effect — friction will cancel out gravity, and the object will stay in midair..

Platformer movement, as it turns out, doesn’t make any goddamn physical sense. What is air control? What are you pushing against? Nothing, really; we just have it because it’s nice to play with, because not having it is a nightmare.

I looked to see if there were any common solutions to this, and I only really found one: make all your walls frictionless.

Game development is full of hacks like this, and I… don’t like them. I can accept that minor hacks are necessary sometimes, but this one makes an early and widespread change to a fundamental system to “fix” something that was wrong in the first place. It also imposes an “invisible” requirement, something I try to avoid at all costs — if you forget to make a particular wall frictionless, you’ll never know unless you happen to try sliding down it.

And so, I swiftly returned to the existing code. It wasn’t too different from what I’d come up with for LÖVE: it applied gravity by hand, tracked the player’s velocity, computed the intended movement each frame, and moved by that amount. The interesting thing was that it used MovePosition, which schedules a movement for the next physics update and stops the movement if the player hits something solid.

It’s kind of a nice hybrid approach, actually; all the “physics” for conscious actors is done by hand, but the physics engine is still used for collision detection. It’s also used for collision rejection — if the player manages to wedge themselves several pixels into a solid object, for example, the physics engine will try to gently nudge them back out of it with no extra effort required on my part. I still haven’t figured out how to get that to work with my homegrown stuff, which is built to prevent overlap rather than to jiggle things out of it.

But wait, what about…

Our player is a dynamic body with rotation lock and no gravity. Why not just use a kinematic body?

I must be missing something, because I do not understand the point of kinematic bodies. I ran into this with Godot, too, which documented them the same way: as intended for use as players and other manually-moved objects. But by default, they don’t even collide with other kinematic bodies or static geometry. What? There’s a checkbox to turn this on, which I enabled, but then I found out that MovePosition doesn’t stop kinematic bodies when they hit something, so I would’ve had to cast along the intended path of movement to figure out when to stop, thus duplicating the same work the physics engine was about to do.

But that’s impossible anyway! Static geometry generally wants to be made of edge colliders, right? They don’t care about concave/convex. Imagine the player is standing on the ground near a wall and tries to move towards the wall. Both the ground and the wall are different edges from the same edge collider.

If you try to cast the player’s hitbox horizontally, parallel to the ground, you’ll only get one collision: the existing collision with the ground. Casting doesn’t distinguish between touching and hitting. And because Unity only reports one collision per collider, and because the ground will always show up first, you will never find out about the impending wall collision.

So you’re forced to either use raycasts for collision detection or decomposed polygons for world geometry, both of which are slightly worse tools for no real gain.

I ended up sticking with a dynamic body.


Oh, one other thing that doesn’t really fit anywhere else: keep track of units! If you’re adding something called “velocity” directly to something called “position”, something has gone very wrong. Acceleration is distance per time squared; velocity is distance per time; position is distance. You must multiply or divide by time to convert between them.

I never even, say, add a constant directly to position every frame; I always phrase it as velocity and multiply by Δt. It keeps the units consistent: time is always in seconds, not in tics.

Problem 2: Slopes

Ah, now we start to get off in the weeds.

A sort of pre-problem here was detecting whether we’re on a slope, which means detecting the ground. The codebase originally used a manual physics query of the area around the player’s feet to check for the ground, which seems to be somewhat common, but that can’t tell me the angle of the detected ground. (It’s also kind of error-prone, since “around the player’s feet” has to be specified by hand and may not stay correct through animations or changes in the hitbox.)

I replaced that with what I’d eventually settled on in LÖVE: detect the ground by detecting collisions, and looking at the normal of the collision. A normal is a vector that points straight out from a surface, so if you’re standing on the ground, the normal points straight up; if you’re on a 10° incline, the normal points 10° away from straight up.

Not all collisions are with the ground, of course, so I assumed something is ground if the normal pointed away from gravity. (I like this definition more than “points upwards”, because it avoids assuming anything about the direction of gravity, which leaves some interesting doors open for later on.) That’s easily detected by taking the dot product — if it’s negative, the collision was with the ground, and I now have the normal of the ground.

Actually doing this in practice was slightly tricky. With my LÖVE engine, I could cram this right into the middle of collision resolution. With Unity, not quite so much. I went through a couple iterations before I really grasped Unity’s execution order, which I guess I will have to briefly recap for this to make sense.

Unity essentially has two update cycles. It performs physics updates at fixed intervals for consistency, and updates everything else just before rendering. Within a single frame, Unity does as many fixed physics updates as it has spare time for (which might be zero, one, or more), then does a regular update, then renders. User code can implement either or both of Update, which runs during a regular update, and FixedUpdate, which runs just before Unity does a physics pass.

So my solution was:

  • At the very end of FixedUpdate, clear the actor’s “on ground” flag and ground normal.

  • During OnCollisionEnter2D and OnCollisionStay2D (which are called from within a physics pass), if there’s a collision that looks like it’s with the ground, set the “on ground” flag and ground normal. (If there are multiple ground collisions, well, good luck figuring out the best way to resolve that! At the moment I’m just taking the first and hoping for the best.)

That means there’s a brief window between the end of FixedUpdate and Unity’s physics pass during which a grounded actor might mistakenly believe it’s not on the ground, which is a bit of a shame, but there are very few good reasons for anything to be happening in that window.

Okay! Now we can do slopes.

Just kidding! First we have to do sliding.

When I first looked at this code, it didn’t apply gravity while the player was on the ground. I think I may have had some problems with detecting the ground as result, since the player was no longer pushing down against it? Either way, it seemed like a silly special case, so I made gravity always apply.

Lo! I was a fool. The player could no longer move.

Why? Because MovePosition does exactly what it promises. If the player collides with something, they’ll stop moving. Applying gravity means that the player is trying to move diagonally downwards into the ground, and so MovePosition stops them immediately.

Hence, sliding. I don’t want the player to actually try to move into the ground. I want them to move the unblocked part of that movement. For flat ground, that means the horizontal part, which is pretty much the same as discarding gravity. For sloped ground, it’s a bit more complicated!

Okay but actually it’s less complicated than you’d think. It can be done with some cross products fairly easily, but Unity makes it even easier with a couple casts. There’s a Vector3.ProjectOnPlane function that projects an arbitrary vector on a plane given by its normal — exactly the thing I want! So I apply that to the attempted movement before passing it along to MovePosition. I do the same thing with the current velocity, to prevent the player from accelerating infinitely downwards while standing on flat ground.

One other thing: I don’t actually use the detected ground normal for this. The player might be touching two ground surfaces at the same time, and I’d want to project on both of them. Instead, I use the player body’s GetContacts method, which returns contact points (and normals!) for everything the player is currently touching. I believe those contact points are tracked by the physics engine anyway, so asking for them doesn’t require any actual physics work.

(Looking at the code I have, I notice that I still only perform the slide for surfaces facing upwards — but I’d want to slide against sloped ceilings, too. Why did I do this? Maybe I should remove that.)

(Also, I’m pretty sure projecting a vector on a plane is non-commutative, which raises the question of which order the projections should happen in and what difference it makes. I don’t have a good answer.)

(I note that my LÖVE setup does something slightly different: it just tries whatever the movement ought to be, and if there’s a collision, then it projects — and tries again with the remaining movement. But I can’t ask Unity to do multiple moves in one physics update, alas.)

Okay! Now, slopes. But actually, with the above work done, slopes are most of the way there already.

One obvious problem is that the player tries to move horizontally even when on a slope, and the easy fix is to change their movement from speed * Vector2.right to speed * new Vector2(ground.y, -ground.x) while on the ground. That’s the ground normal rotated a quarter-turn clockwise, so for flat ground it still points to the right, and in general it points rightwards along the ground. (Note that it assumes the ground normal is a unit vector, but as far as I’m aware, that’s true for all the normals Unity gives you.)

Another issue is that if the player stands motionless on a slope, gravity will cause them to slowly slide down it — because the movement from gravity will be projected onto the slope, and unlike flat ground, the result is no longer zero. For conscious actors only, I counter this by adding the opposite factor to the player’s velocity as part of adding in their walking speed. This matches how the real world works, to some extent: when you’re standing on a hill, you’re exerting some small amount of effort just to stay in place.

(Note that slope resistance is not the same as friction. Okay, yes, in the real world, virtually all resistance to movement happens as a result of friction, but bracing yourself against the ground isn’t the same as being passively resisted.)

From here there are a lot of things you can do, depending on how you think slopes should be handled. You could make the player unable to walk up slopes that are too steep. You could make walking down a slope faster than walking up it. You could make jumping go along the ground normal, rather than straight up. You could raise the player’s max allowed speed while running downhill. Whatever you want, really. Armed with a normal and awareness of dot products, you can do whatever you want.

But first you might want to fix a few aggravating side effects.

Problem 3: Ground adherence

I don’t know if there’s a better name for this. I rarely even see anyone talk about it, which surprises me; it seems like it should be a very common problem.

The problem is: if the player runs up a slope which then abruptly changes to flat ground, their momentum will carry them into the air. For very fast players going off the top of very steep slopes, this makes sense, but it becomes visible even for relatively gentle slopes. It was a mild nightmare in the original release of our game Lunar Depot 38, which has very “rough” ground made up of lots of shallow slopes — so the player is very frequently slightly off the ground, which meant they couldn’t jump, for seemingly no reason. (I even had code to fix this, but I disabled it because of a silly visual side effect that I never got around to fixing.)

Anyway! The reason this is a problem is that game protagonists are generally not boxes sliding around — they have legs. We don’t go flying off the top of real-world hilltops because we put our foot down until it touches the ground.

Simulating this footfall is surprisingly fiddly to get right, especially with someone else’s physics engine. It’s made somewhat easier by Cast, which casts the entire hitbox — no matter what shape it is — in a particular direction, as if it had moved, and tells you all the hypothetical collisions in order.

So I cast the player in the direction of gravity by some distance. If the cast hits something solid with a ground-like collision normal, then the player must be close to the ground, and I move them down to touch it (and set that ground as the new ground normal).

There are some wrinkles.

Wrinkle 1: I only want to do this if the player is off the ground now, but was on the ground last frame, and is not deliberately moving upwards. That latter condition means I want to skip this logic if the player jumps, for example, but also if the player is thrust upwards by a spring or abducted by a UFO or whatever. As long as external code goes through some interface and doesn’t mess with the player’s velocity directly, that shouldn’t be too hard to track.

Wrinkle 2: When does this logic run? It needs to happen after the player moves, which means after a Unity physics pass… but there’s no callback for that point in time. I ended up running it at the beginning of FixedUpdate and the beginning of Update — since I definitely want to do it before rendering happens! That means it’ll sometimes happen twice between physics updates. (I could carefully juggle a flag to skip the second run, but I… didn’t do that. Yet?)

Wrinkle 3: I can’t move the player with MovePosition! Remember, MovePosition schedules a movement, it doesn’t actually perform one; that means if it’s called twice before the physics pass, the first call is effectively ignored. I can’t easily combine the drop with the player’s regular movement, for various fiddly reasons. I ended up doing it “by hand” using transform.Translate, which I think was the “old way” to do manual movement before MovePosition existed. I’m not totally sure if it activates triggers? For that matter, I’m not sure it even notices collisions — but since I did a full-body Cast, there shouldn’t be any anyway.

Wrinkle 4: What, exactly, is “some distance”? I’ve yet to find a satisfying answer for this. It seems like it ought to be based on the player’s current speed and the slope of the ground they’re moving along, but every time I’ve done that math, I’ve gotten totally ludicrous answers that sometimes exceed the size of a tile. But maybe that’s not wrong? Play around, I guess, and think about when the effect should “break” and the player should go flying off the top of a hill.

Wrinkle 5: It’s possible that the player will launch off a slope, hit something, and then be adhered to the ground where they wouldn’t have hit it. I don’t much like this edge case, but I don’t see a way around it either.

This problem is surprisingly awkward for how simple it sounds, and the solution isn’t entirely satisfying. Oh, well; the results are much nicer than the solution. As an added bonus, this also fixes occasional problems with running down a hill and becoming detached from the ground due to precision issues or whathaveyou.

Problem 4: One-way platforms

Ah, what a nightmare.

It took me ages just to figure out how to define one-way platforms. Only block when the player is moving downwards? Nope. Only block when the player is above the platform? Nuh-uh.

Well, okay, yes, those approaches might work for convex players and flat platforms. But what about… sloped, one-way platforms? There’s no reason you shouldn’t be able to have those. If Super Mario World can do it, surely Unity can do it almost 30 years later.

The trick is, again, to look at the collision normal. If it faces away from gravity, the player is hitting a ground-like surface, so the platform should block them. Otherwise (or if the player overlaps the platform), it shouldn’t.

Here’s the catch: Unity doesn’t have conditional collision. I can’t decide, on the fly, whether a collision should block or not. In fact, I think that by the time I get a callback like OnCollisionEnter2D, the physics pass is already over.

I could go the other way and use triggers (which are non-blocking), but then I have the opposite problem: I can’t stop the player on the fly. I could move them back to where they hit the trigger, but I envision all kinds of problems as a result. What if they were moving fast enough to activate something on the other side of the platform? What if something else moved to where I’m trying to shove them back to in the meantime? How does this interact with ground detection and listing contacts, which would rightly ignore a trigger as non-blocking?

I beat my head against this for a while, but the inability to respond to collision conditionally was a huge roadblock. It’s all the more infuriating a problem, because Unity ships with a one-way platform modifier thing. Unfortunately, it seems to have been implemented by someone who has never played a platformer. It’s literally one-way — the player is only allowed to move straight upwards through it, not in from the sides. It also tries to block the player if they’re moving downwards while inside the platform, which invokes clumsy rejection behavior. And this all seems to be built into the physics engine itself somehow, so I can’t simply copy whatever they did.

Eventually, I settled on the following. After calculating attempted movement (including sliding), just at the end of FixedUpdate, I do a Cast along the movement vector. I’m not thrilled about having to duplicate the physics engine’s own work, but I do filter to only things on a “one-way platform” physics layer, which should at least help. For each object the cast hits, I use Physics2D.IgnoreCollision to either ignore or un-ignore the collision between the player and the platform, depending on whether the collision was ground-like or not.

(A lot of people suggested turning off collision between layers, but that can’t possibly work — the player might be standing on one platform while inside another, and anyway, this should work for all actors!)

Again, wrinkles! But fewer this time. Actually, maybe just one: handling the case where the player already overlaps the platform. I can’t just check for that with e.g. OverlapCollider, because that doesn’t distinguish between overlapping and merely touching.

I came up with a fairly simple fix: if I was going to un-ignore the collision (i.e. make the platform block), and the cast distance is reported as zero (either already touching or overlapping), I simply do nothing instead. If I’m standing on the platform, I must have already set it blocking when I was approaching it from the top anyway; if I’m overlapping it, I must have already set it non-blocking to get here in the first place.

I can imagine a few cases where this might go wrong. Moving platforms, especially, are going to cause some interesting issues. But this is the best I can do with what I know, and it seems to work well enough so far.

Oh, and our player can deliberately drop down through platforms, which was easy enough to implement; I just decide the platform is always passable while some button is held down.

Problem 5: Pushers and carriers

I haven’t gotten to this yet! Oh boy, can’t wait. I implemented it in LÖVE, but my way was hilariously invasive; I’m hoping that having a physics engine that supports a handwaved “this pushes that” will help. Of course, you also have to worry about sticking to platforms, for which the recommended solution is apparently to parent the cargo to the platform, which sounds goofy to me? I guess I’ll find out when I throw myself at it later.

Overall result

I ended up with a fairly pleasant-feeling system that supports slopes and one-way platforms and whatnot, with all the same pieces as I came up with for LÖVE. The code somehow ended up as less of a mess, too, but it probably helps that I’ve been down this rabbit hole once before and kinda knew what I was aiming for this time.

Animation of a character running smoothly along the top of an irregular dinosaur skeleton

Sorry that I don’t have a big block of code for you to copy-paste into your project. I don’t think there are nearly enough narrative discussions of these fundamentals, though, so hopefully this is useful to someone. If not, well, look forward to ✨ my book, that I am writing ✨!

Security updates for Friday

Post Syndicated from jake original https://lwn.net/Articles/736317/rss

Security updates have been issued by Arch Linux (botan, flyspray, go, go-pie, pcre2, thunderbird, and wireshark-cli), Fedora (chromium and mingw-poppler), Red Hat (Red Hat JBoss BPM Suite 6.4.6 and Red Hat JBoss BRMS 6.4.6), SUSE (git and kernel), and Ubuntu (libffi and xorg-server, xorg-server-hwe-16.04, xorg-server-lts-xenial).

Pirate Bay is Mining Cryptocurrency Again, No Opt Out

Post Syndicated from Ernesto original https://torrentfreak.com/pirate-bay-is-mining-cryptocurrency-again-no-opt-out-171011/

Last month The Pirate Bay caused some uproar by adding a Javascript-based cryptocurrency miner to its website.

The miner utilizes CPU power from visitors to generate Monero coins for the site, providing an extra source of revenue.

The Pirate Bay only tested the option briefly, but that was enough to inspire many others to follow suit. Now, a few weeks later, Pirate Bay has also turned on the miners again.

The miner is not directly embedded in the site’s core code but runs through an ad script. Many ad blockers and anti-malware tools are stopping these request, but people who don’t use any will see a clear spike in CPU usage when they access the site.

The Pirate Bay team previously said that they were testing the miner to see if it can replace ads. While there is some real revenue potential, for now, it’s running in addition to the regular banners. It’s unclear whether the current mining period is another test or if it will run permanently from now on.

The miner does appear to be throttled to a certain degree, so most users might not even notice that it’s running.

Pirate Bay load requests

Running a cryptocurrency miner such as the Coin-Hive script TPB is currently using is not without risk. Aside from user complaints, there is an issue that may make it harder for the site to operate in the future.

Last week we reported that CDN provider Cloudflare had suspended the account of torrent proxy site ProxyBunker, flagging its coin miner as malware. This means that The Pirate Bay now risks losing the Cloudflare service, which they rely on for DDoS protection, among other things.

Cloudflare’s suspension of ProxyBunker occurred even though the site provided users with an option to disable the miner. This functionality was implemented by Coinhive after the script was misused by some sites, which ran it without alerting their users.

The Pirate Bay currently has no opt-out option, nor has it informed users about the latest mining efforts. This could lead to another problem since Coinhive said it would crack down on customers who failed to keep users in the loop.

“We will verify this opt-in on our servers and will implement it in a way that it can not be circumvented. We will pledge to keep the opt-in intact at all times, without exceptions,” the Coinhive team previously noted.

The Pirate Bay team has not commented on the issue thus far. In theory, it’s possible that a rogue advertiser is responsible for the latest mining efforts. If that’s the case it will be disabled soon enough.

Source: TF, for the latest info on copyright, file-sharing, torrent sites and ANONYMOUS VPN services.

Roku Shows FBI Warning to Pirate Channel Users

Post Syndicated from Ernesto original https://torrentfreak.com/roku-shows-fbi-warning-to-pirate-channel-users-171009/

In recent years it has become much easier to stream movies and TV-shows over the Internet.

Legal services such as Netflix and HBO are flourishing, but at the same time millions of people are streaming from unauthorized sources, often paired with perfectly legal streaming platforms and devices.

Hollywood insiders have dubbed this trend “Piracy 3.0” and are actively working with stakeholders to address the threat. One of the companies rightsholders are working with is Roku, known for its easy-to-use media players.

Earlier this year a Mexican court ordered retailers to take the Roku media player off the shelves. This legal battle is still ongoing, but it was a clear signal to the company, which now has its own anti-piracy team.

Several third-party “private” channels have been removed from the player in recent weeks as they violate Roku’s terms and conditions. These include the hugely popular streaming channel XTV, which offered access to infringing content.

After its removal, XTV briefly returned as XTV 2, but that didn’t last for long. The infringing channel was soon removed again, this time showing the FBI’s anti-piracy seal followed by a rather ominous message.

“FBI Anti-Piracy Warning: Unauthorized copying is punishable under federal law,” it reads. “Roku has removed this unauthorized service due to repeated claims of copyright infringement.”

FBI Warning (via Cordcuttersnews)

The unusual warning was picked up by Cordcuttersnews and states that Roku itself removed the channel.

To some it may seem that the FBI is cracking down on Roku channels, but this is not the case. The anti-piracy seal and associated warning are often used in cases where the organization is not actively involved, to add extra weight. The FBI supports this, as long as certain standards are met.

A Roku spokesperson confirmed to TorrentFreak that they’re using it on their own accord here.

“We want to send a clear message to Roku customers and to publishers that any publication of pirated content on our platform is a violation of law and our platform rules,” the company says.

“We have recently expanded the messaging that we display to customers that install non-certified channels to alert them to the associated risks, and we display the FBI’s publicly available warning when we remove channels for copyright violations.”

The strong language shows that Roku is taking its efforts to crack down on infringing channels very seriously. A few weeks ago the company started to warn users that pirate channels may be removed without prior notice.

Source: TF, for the latest info on copyright, file-sharing, torrent sites and ANONYMOUS VPN services.

Dynamic Users with systemd

Post Syndicated from Lennart Poettering original http://0pointer.net/blog/dynamic-users-with-systemd.html

TL;DR: you may now configure systemd to dynamically allocate a UNIX
user ID for service processes when it starts them and release it when
it stops them. It’s pretty secure, mixes well with transient services,
socket activated services and service templating.

Today we released systemd
235
. Among
other improvements this greatly extends the dynamic user logic of
systemd. Dynamic users are a powerful but little known concept,
supported in its basic form since systemd 232. With this blog story I
hope to make it a bit better known.

The UNIX user concept is the most basic and well-understood security
concept in POSIX operating systems. It is UNIX/POSIX’ primary security
concept, the one everybody can agree on, and most security concepts
that came after it (such as process capabilities, SELinux and other
MACs, user name-spaces, …) in some form or another build on it, extend
it or at least interface with it. If you build a Linux kernel with all
security features turned off, the user concept is pretty much the one
you’ll still retain.

Originally, the user concept was introduced to make multi-user systems
a reality, i.e. systems enabling multiple human users to share the
same system at the same time, cleanly separating their resources and
protecting them from each other. The majority of today’s UNIX systems
don’t really use the user concept like that anymore though. Most of
today’s systems probably have only one actual human user (or even
less!), but their user databases (/etc/passwd) list a good number
more entries than that. Today, the majority of UNIX users in most
environments are system users, i.e. users that are not the technical
representation of a human sitting in front of a PC anymore, but the
security identity a system service — an executable program — runs
as. Event though traditional, simultaneous multi-user systems slowly
became less relevant, their ground-breaking basic concept became the
cornerstone of UNIX security. The OS is nowadays partitioned into
isolated services — and each service runs as its own system user, and
thus within its own, minimal security context.

The people behind the Android OS realized the relevance of the UNIX
user concept as the primary security concept on UNIX, and took its use
even further: on Android not only system services take benefit of the
UNIX user concept, but each UI app gets its own, individual user
identity too — thus neatly separating app resources from each other,
and protecting app processes from each other, too.

Back in the more traditional Linux world things are a bit less
advanced in this area. Even though users are the quintessential UNIX
security concept, allocation and management of system users is still a
pretty limited, raw and static affair. In most cases, RPM or DEB
package installation scripts allocate a fixed number of (usually one)
system users when you install the package of a service that wants to
take benefit of the user concept, and from that point on the system
user remains allocated on the system and is never deallocated again,
even if the package is later removed again. Most Linux distributions
limit the number of system users to 1000 (which isn’t particularly a
lot). Allocating a system user is hence expensive: the number of
available users is limited, and there’s no defined way to dispose of
them after use. If you make use of system users too liberally, you are
very likely to run out of them sooner rather than later.

You may wonder why system users are generally not deallocated when the
package that registered them is uninstalled from a system (at least on
most distributions). The reason for that is one relevant property of
the user concept (you might even want to call this a design flaw):
user IDs are sticky to files (and other objects such as IPC
objects). If a service running as a specific system user creates a
file at some location, and is then terminated and its package and user
removed, then the created file still belongs to the numeric ID (“UID”)
the system user originally got assigned. When the next system user is
allocated and — due to ID recycling — happens to get assigned the same
numeric ID, then it will also gain access to the file, and that’s
generally considered a problem, given that the file belonged to a
potentially very different service once upon a time, and likely should
not be readable or changeable by anything coming after
it. Distributions hence tend to avoid UID recycling which means system
users remain registered forever on a system after they have been
allocated once.

The above is a description of the status quo ante. Let’s now focus on
what systemd’s dynamic user concept brings to the table, to improve
the situation.

Introducing Dynamic Users

With systemd dynamic users we hope to make make it easier and cheaper
to allocate system users on-the-fly, thus substantially increasing the
possible uses of this core UNIX security concept.

If you write a systemd service unit file, you may enable the dynamic
user logic for it by setting the
DynamicUser=
option in its [Service] section to yes. If you do a system user is
dynamically allocated the instant the service binary is invoked, and
released again when the service terminates. The user is automatically
allocated from the UID range 61184–65519, by looking for a so far
unused UID.

Now you may wonder, how does this concept deal with the sticky user
issue discussed above? In order to counter the problem, two strategies
easily come to mind:

  1. Prohibit the service from creating any files/directories or IPC objects

  2. Automatically removing the files/directories or IPC objects the
    service created when it shuts down.

In systemd we implemented both strategies, but for different parts of
the execution environment. Specifically:

  1. Setting DynamicUser=yes implies
    ProtectSystem=strict
    and
    ProtectHome=read-only. These
    sand-boxing options turn off write access to pretty much the whole OS
    directory tree, with a few relevant exceptions, such as the API file
    systems /proc, /sys and so on, as well as /tmp and
    /var/tmp. (BTW: setting these two options on your regular services
    that do not use DynamicUser= is a good idea too, as it drastically
    reduces the exposure of the system to exploited services.)

  2. Setting DynamicUser=yes implies
    PrivateTmp=yes. This
    option sets up /tmp and /var/tmp for the service in a way that it
    gets its own, disconnected version of these directories, that are not
    shared by other services, and whose life-cycle is bound to the
    service’s own life-cycle. Thus if the service goes down, the user is
    removed and all its temporary files and directories with it. (BTW: as
    above, consider setting this option for your regular services that do
    not use DynamicUser= too, it’s a great way to lock things down
    security-wise.)

  3. Setting DynamicUser=yes implies
    RemoveIPC=yes. This
    option ensures that when the service goes down all SysV and POSIX IPC
    objects (shared memory, message queues, semaphores) owned by the
    service’s user are removed. Thus, the life-cycle of the IPC objects is
    bound to the life-cycle of the dynamic user and service, too. (BTW:
    yes, here too, consider using this in your regular services, too!)

With these four settings in effect, services with dynamic users are
nicely sand-boxed. They cannot create files or directories, except in
/tmp and /var/tmp, where they will be removed automatically when
the service shuts down, as will any IPC objects created. Sticky
ownership of files/directories and IPC objects is hence dealt with
effectively.

The
RuntimeDirectory=
option may be used to open up a bit the sandbox to external
programs. If you set it to a directory name of your choice, it will be
created below /run when the service is started, and removed in its
entirety when it is terminated. The ownership of the directory is
assigned to the service’s dynamic user. This way, a dynamic user
service can expose API interfaces (AF_UNIX sockets, …) to other
services at a well-defined place and again bind the life-cycle of it to
the service’s own run-time. Example: set RuntimeDirectory=foobar in
your service, and watch how a directory /run/foobar appears at the
moment you start the service, and disappears the moment you stop
it again. (BTW: Much like the other settings discussed above,
RuntimeDirectory= may be used outside of the DynamicUser= context
too, and is a nice way to run any service with a properly owned,
life-cycle-managed run-time directory.)

Persistent Data

Of course, a service running in such an environment (although already
very useful for many cases!), has a major limitation: it cannot leave
persistent data around it can reuse on a later run. As pretty much the
whole OS directory tree is read-only to it, there’s simply no place it
could put the data that survives from one service invocation to the
next.

With systemd 235 this limitation is removed: there are now three new
settings:
StateDirectory=,
LogsDirectory= and CacheDirectory=. In many ways they operate like
RuntimeDirectory=, but create sub-directories below /var/lib,
/var/log and /var/cache, respectively. There’s one major
difference beyond that however: directories created that way are
persistent, they will survive the run-time cycle of a service, and
thus may be used to store data that is supposed to stay around between
invocations of the service.

Of course, the obvious question to ask now is: how do these three
settings deal with the sticky file ownership problem?

For that we lifted a concept from container managers. Container
managers have a very similar problem: each container and the host
typically end up using a very similar set of numeric UIDs, and unless
user name-spacing is deployed this means that host users might be able
to access the data of specific containers that also have a user by the
same numeric UID assigned, even though it actually refers to a very
different identity in a different context. (Actually, it’s even worse
than just getting access, due to the existence of setuid file bits,
access might translate to privilege elevation.) The way container
managers protect the container images from the host (and from each
other to some level) is by placing the container trees below a
boundary directory, with very restrictive access modes and ownership
(0700 and root:root or so). A host user hence cannot take advantage
of the files/directories of a container user of the same UID inside of
a local container tree, simply because the boundary directory makes it
impossible to even reference files in it. After all on UNIX, in order
to get access to a specific path you need access to every single
component of it.

How is that applied to dynamic user services? Let’s say
StateDirectory=foobar is set for a service that has DynamicUser=
turned off. The instant the service is started, /var/lib/foobar is
created as state directory, owned by the service’s user and remains in
existence when the service is stopped. If the same service now is run
with DynamicUser= turned on, the implementation is slightly
altered. Instead of a directory /var/lib/foobar a symbolic link by
the same path is created (owned by root), pointing to
/var/lib/private/foobar (the latter being owned by the service’s
dynamic user). The /var/lib/private directory is created as boundary
directory: it’s owned by root:root, and has a restrictive access
mode of 0700. Both the symlink and the service’s state directory will
survive the service’s life-cycle, but the state directory will remain,
and continues to be owned by the now disposed dynamic UID — however it
is protected from other host users (and other services which might get
the same dynamic UID assigned due to UID recycling) by the boundary
directory.

The obvious question to ask now is: but if the boundary directory
prohibits access to the directory from unprivileged processes, how can
the service itself which runs under its own dynamic UID access it
anyway? This is achieved by invoking the service process in a slightly
modified mount name-space: it will see most of the file hierarchy the
same way as everything else on the system (modulo /tmp and
/var/tmp as mentioned above), except for /var/lib/private, which
is over-mounted with a read-only tmpfs file system instance, with a
slightly more liberal access mode permitting the service read
access. Inside of this tmpfs file system instance another mount is
placed: a bind mount to the host’s real /var/lib/private/foobar
directory, onto the same name. Putting this together these means that
superficially everything looks the same and is available at the same
place on the host and from inside the service, but two important
changes have been made: the /var/lib/private boundary directory lost
its restrictive character inside the service, and has been emptied of
the state directories of any other service, thus making the protection
complete. Note that the symlink /var/lib/foobar hides the fact that
the boundary directory is used (making it little more than an
implementation detail), as the directory is available this way under
the same name as it would be if DynamicUser= was not used. Long
story short: for the daemon and from the view from the host the
indirection through /var/lib/private is mostly transparent.

This logic of course raises another question: what happens to the
state directory if a dynamic user service is started with a state
directory configured, gets UID X assigned on this first invocation,
then terminates and is restarted and now gets UID Y assigned on the
second invocation, with X ≠ Y? On the second invocation the directory
— and all the files and directories below it — will still be owned by
the original UID X so how could the second instance running as Y
access it? Our way out is simple: systemd will recursively change the
ownership of the directory and everything contained within it to UID Y
before invoking the service’s executable.

Of course, such recursive ownership changing (chown()ing) of whole
directory trees can become expensive (though according to my
experiences, IRL and for most services it’s much cheaper than you
might think), hence in order to optimize behavior in this regard, the
allocation of dynamic UIDs has been tweaked in two ways to avoid the
necessity to do this expensive operation in most cases: firstly, when
a dynamic UID is allocated for a service an allocation loop is
employed that starts out with a UID hashed from the service’s
name. This means a service by the same name is likely to always use
the same numeric UID. That means that a stable service name translates
into a stable dynamic UID, and that means recursive file ownership
adjustments can be skipped (of course, after validation). Secondly, if
the configured state directory already exists, and is owned by a
suitable currently unused dynamic UID, it’s preferably used above
everything else, thus maximizing the chance we can avoid the
chown()ing. (That all said, ultimately we have to face it, the
currently available UID space of 4K+ is very small still, and
conflicts are pretty likely sooner or later, thus a chown()ing has to
be expected every now and then when this feature is used extensively).

Note that CacheDirectory= and LogsDirectory= work very similar to
StateDirectory=. The only difference is that they manage directories
below the /var/cache and /var/logs directories, and their boundary
directory hence is /var/cache/private and /var/log/private,
respectively.

Examples

So, after all this introduction, let’s have a look how this all can be
put together. Here’s a trivial example:

# cat > /etc/systemd/system/dynamic-user-test.service <<EOF
[Service]
ExecStart=/usr/bin/sleep 4711
DynamicUser=yes
EOF
# systemctl daemon-reload
# systemctl start dynamic-user-test
# systemctl status dynamic-user-test
● dynamic-user-test.service
   Loaded: loaded (/etc/systemd/system/dynamic-user-test.service; static; vendor preset: disabled)
   Active: active (running) since Fri 2017-10-06 13:12:25 CEST; 3s ago
 Main PID: 2967 (sleep)
    Tasks: 1 (limit: 4915)
   CGroup: /system.slice/dynamic-user-test.service
           └─2967 /usr/bin/sleep 4711

Okt 06 13:12:25 sigma systemd[1]: Started dynamic-user-test.service.
# ps -e -o pid,comm,user | grep 2967
 2967 sleep           dynamic-user-test
# id dynamic-user-test
uid=64642(dynamic-user-test) gid=64642(dynamic-user-test) groups=64642(dynamic-user-test)
# systemctl stop dynamic-user-test
# id dynamic-user-test
id: ‘dynamic-user-test’: no such user

In this example, we create a unit file with DynamicUser= turned on,
start it, check if it’s running correctly, have a look at the service
process’ user (which is named like the service; systemd does this
automatically if the service name is suitable as user name, and you
didn’t configure any user name to use explicitly), stop the service
and verify that the user ceased to exist too.

That’s already pretty cool. Let’s step it up a notch, by doing the
same in an interactive transient service (for those who don’t know
systemd well: a transient service is a service that is defined and
started dynamically at run-time, for example via the systemd-run
command from the shell. Think: run a service without having to write a
unit file first):

# systemd-run --pty --property=DynamicUser=yes --property=StateDirectory=wuff /bin/sh
Running as unit: run-u15750.service
Press ^] three times within 1s to disconnect TTY.
sh-4.4$ id
uid=63122(run-u15750) gid=63122(run-u15750) groups=63122(run-u15750) context=system_u:system_r:initrc_t:s0
sh-4.4$ ls -al /var/lib/private/
total 0
drwxr-xr-x. 3 root       root        60  6. Okt 13:21 .
drwxr-xr-x. 1 root       root       852  6. Okt 13:21 ..
drwxr-xr-x. 1 run-u15750 run-u15750   8  6. Okt 13:22 wuff
sh-4.4$ ls -ld /var/lib/wuff
lrwxrwxrwx. 1 root root 12  6. Okt 13:21 /var/lib/wuff -> private/wuff
sh-4.4$ ls -ld /var/lib/wuff/
drwxr-xr-x. 1 run-u15750 run-u15750 0  6. Okt 13:21 /var/lib/wuff/
sh-4.4$ echo hello > /var/lib/wuff/test
sh-4.4$ exit
exit
# id run-u15750
id: ‘run-u15750’: no such user
# ls -al /var/lib/private
total 0
drwx------. 1 root  root   66  6. Okt 13:21 .
drwxr-xr-x. 1 root  root  852  6. Okt 13:21 ..
drwxr-xr-x. 1 63122 63122   8  6. Okt 13:22 wuff
# ls -ld /var/lib/wuff
lrwxrwxrwx. 1 root root 12  6. Okt 13:21 /var/lib/wuff -> private/wuff
# ls -ld /var/lib/wuff/
drwxr-xr-x. 1 63122 63122 8  6. Okt 13:22 /var/lib/wuff/
# cat /var/lib/wuff/test
hello

The above invokes an interactive shell as transient service
run-u15750.service (systemd-run picked that name automatically,
since we didn’t specify anything explicitly) with a dynamic user whose
name is derived automatically from the service name. Because
StateDirectory=wuff is used, a persistent state directory for the
service is made available as /var/lib/wuff. In the interactive shell
running inside the service, the ls commands show the
/var/lib/private boundary directory and its contents, as well as the
symlink that is placed for the service. Finally, before exiting the
shell, a file is created in the state directory. Back in the original
command shell we check if the user is still allocated: it is not, of
course, since the service ceased to exist when we exited the shell and
with it the dynamic user associated with it. From the host we check
the state directory of the service, with similar commands as we did
from inside of it. We see that things are set up pretty much the same
way in both cases, except for two things: first of all the user/group
of the files is now shown as raw numeric UIDs instead of the
user/group names derived from the unit name. That’s because the user
ceased to exist at this point, and “ls” shows the raw UID for files
owned by users that don’t exist. Secondly, the access mode of the
boundary directory is different: when we look at it from outside of
the service it is not readable by anyone but root, when we looked from
inside we saw it it being world readable.

Now, let’s see how things look if we start another transient service,
reusing the state directory from the first invocation:

# systemd-run --pty --property=DynamicUser=yes --property=StateDirectory=wuff /bin/sh
Running as unit: run-u16087.service
Press ^] three times within 1s to disconnect TTY.
sh-4.4$ cat /var/lib/wuff/test
hello
sh-4.4$ ls -al /var/lib/wuff/
total 4
drwxr-xr-x. 1 run-u16087 run-u16087  8  6. Okt 13:22 .
drwxr-xr-x. 3 root       root       60  6. Okt 15:42 ..
-rw-r--r--. 1 run-u16087 run-u16087  6  6. Okt 13:22 test
sh-4.4$ id
uid=63122(run-u16087) gid=63122(run-u16087) groups=63122(run-u16087) context=system_u:system_r:initrc_t:s0
sh-4.4$ exit
exit

Here, systemd-run picked a different auto-generated unit name, but
the used dynamic UID is still the same, as it was read from the
pre-existing state directory, and was otherwise unused. As we can see
the test file we generated earlier is accessible and still contains
the data we left in there. Do note that the user name is different
this time (as it is derived from the unit name, which is different),
but the UID it is assigned to is the same one as on the first
invocation. We can thus see that the mentioned optimization of the UID
allocation logic (i.e. that we start the allocation loop from the UID
owner of any existing state directory) took effect, so that no
recursive chown()ing was required.

And that’s the end of our example, which hopefully illustrated a bit
how this concept and implementation works.

Use-cases

Now that we had a look at how to enable this logic for a unit and how
it is implemented, let’s discuss where this actually could be useful
in real life.

  • One major benefit of dynamic user IDs is that running a
    privilege-separated service leaves no artifacts in the system. A
    system user is allocated and made use of, but it is discarded
    automatically in a safe and secure way after use, in a fashion that is
    safe for later recycling. Thus, quickly invoking a short-lived service
    for processing some job can be protected properly through a user ID
    without having to pre-allocate it and without this draining the
    available UID pool any longer than necessary.

  • In many cases, starting a service no longer requires
    package-specific preparation. Or in other words, quite often
    useradd/mkdir/chown/chmod invocations in “post-inst” package
    scripts, as well as
    sysusers.d
    and
    tmpfiles.d
    drop-ins become unnecessary, as the DynamicUser= and
    StateDirectory=/CacheDirectory=/LogsDirectory= logic can do the
    necessary work automatically, on-demand and with a well-defined
    life-cycle.

  • By combining dynamic user IDs with the transient unit concept, new
    creative ways of sand-boxing are made available. For example, let’s say
    you don’t trust the correct implementation of the sort command. You
    can now lock it into a simple, robust, dynamic UID sandbox with a
    simple systemd-run and still integrate it into a shell pipeline like
    any other command. Here’s an example, showcasing a shell pipeline
    whose middle element runs as a dynamically on-the-fly allocated UID,
    that is released when the pipelines ends.

    # cat some-file.txt | systemd-run ---pipe --property=DynamicUser=1 sort -u | grep -i foobar > some-other-file.txt
    
  • By combining dynamic user IDs with the systemd templating logic it
    is now possible to do much more fine-grained and fully automatic UID
    management. For example, let’s say you have a template unit file
    /etc/systemd/system/[email protected]:

    [Service]
    ExecStart=/usr/bin/myfoobarserviced
    DynamicUser=1
    StateDirectory=foobar/%i
    

    Now, let’s say you want to start one instance of this service for
    each of your customers. All you need to do now for that is:

    # systemctl enable [email protected] --now
    

    And you are done. (Invoke this as many times as you like, each time
    replacing customerxyz by some customer identifier, you get the
    idea.)

  • By combining dynamic user IDs with socket activation you may easily
    implement a system where each incoming connection is served by a
    process instance running as a different, fresh, newly allocated UID
    within its own sandbox. Here’s an example waldo.socket:

    [Socket]
    ListenStream=2048
    Accept=yes
    

    With a matching [email protected]:

    [Service]
    ExecStart=-/usr/bin/myservicebinary
    DynamicUser=yes
    

    With the two unit files above, systemd will listen on TCP/IP port
    2048, and for each incoming connection invoke a fresh instance of
    [email protected], each time utilizing a different, new,
    dynamically allocated UID, neatly isolated from any other
    instance.

  • Dynamic user IDs combine very well with state-less systems,
    i.e. systems that come up with an unpopulated /etc and /var. A
    service using dynamic user IDs and the StateDirectory=,
    CacheDirectory=, LogsDirectory= and RuntimeDirectory= concepts
    will implicitly allocate the users and directories it needs for
    running, right at the moment where it needs it.

Dynamic users are a very generic concept, hence a multitude of other
uses are thinkable; the list above is just supposed to trigger your
imagination.

What does this mean for you as a packager?

I am pretty sure that a large number of services shipped with today’s
distributions could benefit from using DynamicUser= and
StateDirectory= (and related settings). It often allows removal of
post-inst packaging scripts altogether, as well as any sysusers.d
and tmpfiles.d drop-ins by unifying the needed declarations in the
unit file itself. Hence, as a packager please consider switching your
unit files over. That said, there are a number of conditions where
DynamicUser= and StateDirectory= (and friends) cannot or should
not be used. To name a few:

  1. Service that need to write to files outside of /run/<package>,
    /var/lib/<package>, /var/cache/<package>, /var/log/<package>,
    /var/tmp, /tmp, /dev/shm are generally incompatible with this
    scheme. This rules out daemons that upgrade the system as one example,
    as that involves writing to /usr.

  2. Services that maintain a herd of processes with different user
    IDs. Some SMTP services are like this. If your service has such a
    super-server design, UID management needs to be done by the
    super-server itself, which rules out systemd doing its dynamic UID
    magic for it.

  3. Services which run as root (obviously…) or are otherwise
    privileged.

  4. Services that need to live in the same mount name-space as the host
    system (for example, because they want to establish mount points
    visible system-wide). As mentioned DynamicUser= implies
    ProtectSystem=, PrivateTmp= and related options, which all require
    the service to run in its own mount name-space.

  5. Your focus is older distributions, i.e. distributions that do not
    have systemd 232 (for DynamicUser=) or systemd 235 (for
    StateDirectory= and friends) yet.

  6. If your distribution’s packaging guides don’t allow it. Consult
    your packaging guides, and possibly start a discussion on your
    distribution’s mailing list about this.

Notes

A couple of additional, random notes about the implementation and use
of these features:

  1. Do note that allocating or deallocating a dynamic user leaves
    /etc/passwd untouched. A dynamic user is added into the user
    database through the glibc NSS module
    nss-systemd,
    and this information never hits the disk.

  2. On traditional UNIX systems it was the job of the daemon process
    itself to drop privileges, while the DynamicUser= concept is
    designed around the service manager (i.e. systemd) being responsible
    for that. That said, since v235 there’s a way to marry DynamicUser=
    and such services which want to drop privileges on their own. For
    that, turn on DynamicUser= and set
    User=
    to the user name the service wants to setuid() to. This has the
    effect that systemd will allocate the dynamic user under the specified
    name when the service is started. Then, prefix the command line you
    specify in
    ExecStart=
    with a single ! character. If you do, the user is allocated for the
    service, but the daemon binary is is invoked as root instead of the
    allocated user, under the assumption that the daemon changes its UID
    on its own the right way. Not that after registration the user will
    show up instantly in the user database, and is hence resolvable like
    any other by the daemon process. Example:
    ExecStart=!/usr/bin/mydaemond

  3. You may wonder why systemd uses the UID range 61184–65519 for its
    dynamic user allocations (side note: in hexadecimal this reads as
    0xEF00–0xFFEF). That’s because distributions (specifically Fedora)
    tend to allocate regular users from below the 60000 range, and we
    don’t want to step into that. We also want to stay away from 65535 and
    a bit around it, as some of these UIDs have special meanings (65535 is
    often used as special value for “invalid” or “no” UID, as it is
    identical to the 16bit value -1; 65534 is generally mapped to the
    “nobody” user, and is where some kernel subsystems map unmappable
    UIDs). Finally, we want to stay within the 16bit range. In a user
    name-spacing world each container tends to have much less than the full
    32bit UID range available that Linux kernels theoretically
    provide. Everybody apparently can agree that a container should at
    least cover the 16bit range though — already to include a nobody
    user. (And quite frankly, I am pretty sure assigning 64K UIDs per
    container is nicely systematic, as the the higher 16bit of the 32bit
    UID values this way become a container ID, while the lower 16bit
    become the logical UID within each container, if you still follow what
    I am babbling here…). And before you ask: no this range cannot be
    changed right now, it’s compiled in. We might change that eventually
    however.

  4. You might wonder what happens if you already used UIDs from the
    61184–65519 range on your system for other purposes. systemd should
    handle that mostly fine, as long as that usage is properly registered
    in the user database: when allocating a dynamic user we pick a UID,
    see if it is currently used somehow, and if yes pick a different one,
    until we find a free one. Whether a UID is used right now or not is
    checked through NSS calls. Moreover the IPC object lists are checked to
    see if there are any objects owned by the UID we are about to
    pick. This means systemd will avoid using UIDs you have assigned
    otherwise. Note however that this of course makes the pool of
    available UIDs smaller, and in the worst cases this means that
    allocating a dynamic user might fail because there simply are no
    unused UIDs in the range.

  5. If not specified otherwise the name for a dynamically allocated
    user is derived from the service name. Not everything that’s valid in
    a service name is valid in a user-name however, and in some cases a
    randomized name is used instead to deal with this. Often it makes
    sense to pick the user names to register explicitly. For that use
    User= and choose whatever you like.

  6. If you pick a user name with User= and combine it with
    DynamicUser= and the user already exists statically it will be used
    for the service and the dynamic user logic is automatically
    disabled. This permits automatic up- and downgrades between static and
    dynamic UIDs. For example, it provides a nice way to move a system
    from static to dynamic UIDs in a compatible way: as long as you select
    the same User= value before and after switching DynamicUser= on,
    the service will continue to use the statically allocated user if it
    exists, and only operates in the dynamic mode if it does not. This is
    useful for other cases as well, for example to adapt a service that
    normally would use a dynamic user to concepts that require statically
    assigned UIDs, for example to marry classic UID-based file system
    quota with such services.

  7. systemd always allocates a pair of dynamic UID and GID at the same
    time, with the same numeric ID.

  8. If the Linux kernel had a “shiftfs” or similar functionality,
    i.e. a way to mount an existing directory to a second place, but map
    the exposed UIDs/GIDs in some way configurable at mount time, this
    would be excellent for the implementation of StateDirectory= in
    conjunction with DynamicUser=. It would make the recursive
    chown()ing step unnecessary, as the host version of the state
    directory could simply be mounted into a the service’s mount
    name-space, with a shift applied that maps the directory’s owner to the
    services’ UID/GID. But I don’t have high hopes in this regard, as all
    work being done in this area appears to be bound to user name-spacing
    — which is a concept not used here (and I guess one could say user
    name-spacing is probably more a source of problems than a solution to
    one, but you are welcome to disagree on that).

And that’s all for now. Enjoy your dynamic users!

Cryptocurrency Miner Targeted by Anti-Virus and Adblock Tools

Post Syndicated from Ernesto original https://torrentfreak.com/cryptocurrency-miner-targeted-by-anti-virus-and-adblock-tools-170926/

Earlier this month The Pirate Bay caused some uproar by adding a Javascript-based cryptocurrency miner to its website.

The miner utilizes CPU power from visitors to generate Monero coins for the site, providing an extra revenue source.

While Pirate Bay only tested the option briefly, it inspired many others to follow suit. Streaming related sites such as Alluc, Vidoza, and Rapidvideo jumped on board, and torrent site Demonoid also ran some tests.

During the weekend, Coinhive’s miner code even appeared on the official website of Showtime. The code was quickly removed and it’s still unclear how it got there, as the company refuses to comment. It’s clear, though, that miners are a hot topic thanks to The Pirate Bay.

The revenue potential is also real. TorrentFreak spoke to Vidoza who say that with 30,000 online users throughout the day (2M unique visitors), they can make between $500 and $600. That’s when the miner is throttled at 50%. Although ads can bring in more, it’s not insignificant.

That said, all the uproar about cryptocurrency miners and their possible abuse has also attracted the attention of ad-blockers. Some people have coded new browser add-ons to block miners specifically and the popular uBlock Origin added Coinhive to its default blocklist as well. And that’s just after a few days.

Needless to say, this limits the number of miners, and thus the money that comes in. And there’s another problem with a similar effect.

In addition to ad-blockers, anti-virus tools are also flagging Coinhive. Malwarebytes is one of the companies that lists it as a malicious activity, warning users about the threat.

The anti-virus angle is one of the issues that worries Demonoid’s operator. The site is used to ad-blockers, but getting flagged by anti-virus companies is of a different order.

“The problem I see there and the reason we will likely discontinue [use of the miner] is that some anti-virus programs block it, and that might get the site on their blacklists,” Deimos informs TorrentFreak.

Demonoid’s miner announcement

Vidoza operator Eugene sees all the blocking as an unwelcome development and hopes that Coinhive will tackle it. Coinhive may want to come out in public and start to discuss the issue with ad-blockers and anti-virus companies, he says.

“They should find out under what conditions all these guys will stop blocking the script,” he notes.

The other option would be to circumvent the blocking through proxies and circumvention tools, but that might not be the best choice in the long run.

Coinhive, meanwhile, has chimed in as well. The company says that it wasn’t properly prepared for the massive attention and understands why some ad-blockers have put them on the blacklist.

“Providing a real alternative to ads and users who block them turned out to be a much harder problem. Coinhive, too, is now blocked by many ad-block browser extensions, which – we have to admit – is reasonable at this point.”

Most complaints have been targeted at sites that implemented the miner without the user’s consent. Coinhive doesn’t like this either and will take steps to prevent it in future.

“We’re a bit saddened to see that some of our customers integrate Coinhive into their pages without disclosing to their users what’s going on, let alone asking for their permission,” the Coinhive team notes.

The crypto miner provider is working on a new implementation that requires explicit consent from website visitors in order to run. This should deal with most of the negative responses.

If users start mining voluntarily, then ad-blockers and anti-virus companies should no longer have a reason to block the script. Nor will it be easy for malware peddlers to abuse it.

To be continued.

Source: TF, for the latest info on copyright, file-sharing, torrent sites and ANONYMOUS VPN services.

Astro Pi upgrades on the International Space Station

Post Syndicated from David Honess original https://www.raspberrypi.org/blog/astro-pi-upgrades/

In 2015, The Raspberry Pi Foundation built two space-hardened Raspberry Pi units, or Astro Pis, to run student code on board the International Space Station (ISS).

Astro Pi

A space-hardened Raspberry Pi

Astro Pi upgrades

Each school year we run an Astro Pi challenge to find the next generation of space scientists to program them. After the students have their code run in space, any output files are downloaded to ground and returned to them for analysis.

That download process was originally accomplished by an astronaut shutting down the Astro Pi, moving its micro SD card to a crew laptop and copying over the files manually. This used about 20 minutes of precious crew time.

space pi – Create, Discover and Share Awesome GIFs on Gfycat

Watch space pi GIF by sooperdave on Gfycat. Discover more GIFS online on Gfycat

Last year, we passed the qualification to allow the Astro Pi computers to be connected to the Local Area Network (LAN) on board the ISS. This allows us to remotely access them from the ground, upload student code and download the results without having to involve the crew.

This year, we have been preparing a new payload to upgrade the operational capabilities of the Astro Pi units.

The payload consists of the following items:

  • 2 × USB WiFi dongles
  • 5 × optical filters
  • 4 × 32GB micro SD cards

Before anyone asks – no, we’re not going outside into the vacuum of space!

USB WiFi dongle

Currently both Astro Pi units are located in the European Columbus module. They’re even visible on Google Street View (pan down and right)! You can see that we’ve created a bit of a bird’s nest of wires behind them.

Astro Pi

The D-Link DWA-171

The decision to add WiFi capability is partly to clean up the cabling situation, but mainly so that the Astro Pi units can be deployed in ISS locations other than the Columbus module, where we won’t have access to an Ethernet switch.

The Raspberry Pi used in the Astro Pi flight units is the B+ (released in 2014), which does not have any built in wireless connectivity, so we need to use a USB dongle. This particular D-Link dongle was recommended by the European Space Agency (ESA) because a number of other payloads are already using it.

Astro Pi

An Astro Pi unit with WiFi dongle installed

Plans have been made for one of the Astro Pi units to be deployed on an Earth-facing window, to allow Earth-observation student experiments. This is where WiFi connectivity will be required to maintain LAN access for ground control.

Optical filters

With Earth-observation experiments in mind, we are also sending some flexible film optical filters. These are made from the same material as the blue square which is shipped with the Pi NoIR camera module, as noted in this post from when the product was launched. You can find the data sheet here.

Astro Pi

Rosco Roscalux #2007 Storaro Blue

To permit the filter to be easily attached to the Astro Pi unit, the film is laser-cut to friction-fit onto the 12 inner heatsink pins on the base, so that the camera aperture is covered.

Astro Pi

Laser cutting at Makespace

The laser-cutting work was done right here in Cambridge at Makespace by our own Alex Bate, and local artist Diana Probst.

Astro Pi

An Astro Pi with the optical filter installed

32GB micro SD cards

A consequence of running Earth observation experiments is a dramatic increase in the amount of disk space needed. To avoid a high frequency of commanding windows to download imagery to ground, we’re also flying some larger 32GB micro SD cards to replace the current 8GB cards.

Astro Pi

The Samsung Evo MB-MP32DA/EU

This particular type of micro SD card is X-ray proof, waterproof, and resistant to magnetism and heat. Operationally speaking there is no difference, other than the additional available disk space.

Astro Pi

An Astro Pi unit with the new micro SD card installed

The micro SD cards will be flown with a security-hardened version of Raspbian pre-installed.

Crew activities

We have several crew activities planned for when this payload arrives on the ISS. These include the installation of the upgrade items on both Astro Pi units; moving one of the units from Columbus to an earth-facing window (possibly in Node 2); and then moving it back a few weeks later.

Currently it is expected that these activities will be carried out by German ESA astronaut Alexander Gerst who launches to the ISS in November (and will also be the ISS commander for Expedition 57).

Payload launch

We are targeting a January 2018 launch date for the payload. The exact launch vehicle is yet to be determined, but it could be SpaceX CRS 14. We will update you closer to the time.

Questions?

If you have any questions about this payload, how an item works, or why that specific model was chosen, please post them in the comments below, and we’ll try to answer them.

The post Astro Pi upgrades on the International Space Station appeared first on Raspberry Pi.

Simplify Your Jenkins Builds with AWS CodeBuild

Post Syndicated from Paul Roberts original https://aws.amazon.com/blogs/devops/simplify-your-jenkins-builds-with-aws-codebuild/

Jeff Bezos famously said, “There’s a lot of undifferentiated heavy lifting that stands between your idea and that success.” He went on to say, “…70% of your time, energy, and dollars go into the undifferentiated heavy lifting and only 30% of your energy, time, and dollars gets to go into the core kernel of your idea.”

If you subscribe to this maxim, you should not be spending valuable time focusing on operational issues related to maintaining the Jenkins build infrastructure. Companies such as Riot Games have over 1.25 million builds per year and have written several lengthy blog posts about their experiences designing a complex, custom Docker-powered Jenkins build farm. Dealing with Jenkins slaves at scale is a job in itself and Riot has engineers focused on managing the build infrastructure.

Typical Jenkins Build Farm

 

As with all technology, the Jenkins build farm architectures have evolved. Today, instead of manually building your own container infrastructure, there are Jenkins Docker plugins available to help reduce the operational burden of maintaining these environments. There is also a community-contributed Amazon EC2 Container Service (Amazon ECS) plugin that helps remove some of the overhead, but you still need to configure and manage the overall Amazon ECS environment.

There are various ways to create and manage your Jenkins build farm, but there has to be a way that significantly reduces your operational overhead.

Introducing AWS CodeBuild

AWS CodeBuild is a fully managed build service that removes the undifferentiated heavy lifting of provisioning, managing, and scaling your own build servers. With CodeBuild, there is no software to install, patch, or update. CodeBuild scales up automatically to meet the needs of your development teams. In addition, CodeBuild is an on-demand service where you pay as you go. You are charged based only on the number of minutes it takes to complete your build.

One AWS customer, Recruiterbox, helps companies hire simply and predictably through their software platform. Two years ago, they began feeling the operational pain of maintaining their own Jenkins build farms. They briefly considered moving to Amazon ECS, but chose an even easier path forward instead. Recuiterbox transitioned to using Jenkins with CodeBuild and are very happy with the results. You can read more about their journey here.

Solution Overview: Jenkins and CodeBuild

To remove the heavy lifting from managing your Jenkins build farm, AWS has developed a Jenkins AWS CodeBuild plugin. After the plugin has been enabled, a developer can configure a Jenkins project to pick up new commits from their chosen source code repository and automatically run the associated builds. After the build is successful, it will create an artifact that is stored inside an S3 bucket that you have configured. If an error is detected somewhere, CodeBuild will capture the output and send it to Amazon CloudWatch logs. In addition to storing the logs on CloudWatch, Jenkins also captures the error so you do not have to go hunting for log files for your build.

 

AWS CodeBuild with Jenkins Plugin

 

The following example uses AWS CodeCommit (Git) as the source control management (SCM) and Amazon S3 for build artifact storage. Logs are stored in CloudWatch. A development pipeline that uses Jenkins with CodeBuild plugin architecture looks something like this:

 

AWS CodeBuild Diagram

Initial Solution Setup

To keep this blog post succinct, I assume that you are using the following components on AWS already and have applied the appropriate IAM policies:

·         AWS CodeCommit repo.

·         Amazon S3 bucket for CodeBuild artifacts.

·         SNS notification for text messaging of the Jenkins admin password.

·         IAM user’s key and secret.

·         A role that has a policy with these permissions. Be sure to edit the ARNs with your region, account, and resource name. Use this role in the AWS CloudFormation template referred to later in this post.

 

Jenkins Installation with CodeBuild Plugin Enabled

To make the integration with Jenkins as frictionless as possible, I have created an AWS CloudFormation template here: https://s3.amazonaws.com/proberts-public/jenkins.yaml. Download the template, sign in the AWS CloudFormation console, and then use the template to create a stack.

 

CloudFormation Inputs

Jenkins Project Configuration

After the stack is complete, log in to the Jenkins EC2 instance using the user name “admin” and the password sent to your mobile device. Now that you have logged in to Jenkins, you need to create your first project. Start with a Freestyle project and configure the parameters based on your CodeBuild and CodeCommit settings.

 

AWS CodeBuild Plugin Configuration in Jenkins

 

Additional Jenkins AWS CodeBuild Plugin Configuration

 

After you have configured the Jenkins project appropriately you should be able to check your build status on the Jenkins polling log under your project settings:

 

Jenkins Polling Log

 

Now that Jenkins is polling CodeCommit, you can check the CodeBuild dashboard under your Jenkins project to confirm your build was successful:

Jenkins AWS CodeBuild Dashboard

Wrapping Up

In a matter of minutes, you have been able to provision Jenkins with the AWS CodeBuild plugin. This will greatly simplify your build infrastructure management. Now kick back and relax while CodeBuild does all the heavy lifting!


About the Author

Paul Roberts is a Strategic Solutions Architect for Amazon Web Services. When he is not working on Serverless, DevOps, or Artificial Intelligence, he is often found in Lake Tahoe exploring the various mountain ranges with his family.

[$] A last-minute MMU notifier change

Post Syndicated from corbet original https://lwn.net/Articles/732952/rss

One does not normally expect to see significant changes to an important
internal memory-management mechanism in the time between the ‑rc7 prepatch
and the final release for a development cycle, but that is exactly what
happened just before 4.13 was released. A regression involving the
memory-management unit (MMU) notifier mechanism briefly threatened to
delay this release, but a last-minute scramble kept 4.13 on
schedule and also resulted in a cleanup of that mechanism.
This seems like a good time to look at a mechanism that Linus
Torvalds called “a badly designed mistake” and how it was made
to be a bit less mistaken.

Mystery Codes Appear in ‘Pirate’ Mayweather v McGregor Streams

Post Syndicated from Andy original https://torrentfreak.com/mystery-codes-appear-in-pirate-mayweather-v-mcgregor-streams-170827/

For many hardcore boxing fans, it was the fight that should never have taken place. But last night, undefeated legend Floyd Mayweather stepped into the ring against UFC lightweight champion and supposed boxing novice, Conor McGregor.

A known slow starter, Mayweather came out true to form, arguably losing the first three rounds to the brash Irishman who had previously promised to bounce the 40-year-old’s head off the canvas in round one. But by round 10 it was all over, with McGregor running out of gas and with no answer to Mayweather’s increasingly vicious punches. TKO Mayweather.

While viewing figures won’t be in for some time, the event is likely to have been a massive PPV success all over the world, with millions tuning in for what turned out to be a value-for-money event. But despite widespread availability, it’s likely that hundreds of thousands – maybe even millions – tuned into the fight from unofficial sources. Interestingly, some of those had a little extra something thrown in for free.

During the fight, TF received an unsubstantiated report that an unusual watermark was being embedded into streams originally broadcast by Sky Box Office in the UK. The message we received simply told us there were codes on the screen, but we were unable to get any further information from the source who had already gone offline.

Quick inquiries with two other sources watching pirate streams confirmed that codes had appeared on their screens too. One managed to take a series of photographs which are included below. (Note: portions of the code are redacted to protect the source)

The mystery sequence of numbers

The letter and number combinations briefly appeared in 20 to 23 sets of pairs, which according to the images seen by TF stayed the same throughout the broadcast. It is possible there was some variation but nothing we’ve seen suggests that. The big question, of course, is why they were put there and by whom.

According to our sources, these codes didn’t appear when the main action was taking place but when the camera turned to people in each corner. Since no digits appeared over the top of the fight itself, it might suggest that they were put there by a broadcaster, in this instance Sky Box Office, who were licensed to show the fight in the UK.

If that was indeed the case, it’s certainly possible that the sequence of numbers would allow Sky to track the illicit stream back to a subscriber and/or a set-top box tied to a particular account. Since that subscriber has then re-streamed that content back online illegally, the code would act as a homing beacon and could spell bad news for the individual involved.

The other possibility is that the codes were not put there by Sky or another official broadcaster in the chain, but by someone in the illicit streaming market. Pirate streams are vulnerable to being ‘stolen’ in much the same way that official streams are, so it’s possible that a provider wanted to keep tabs on where its streams were ending up.

The big question is why, with all the sophisticated technology available in 2017, were the watermark codes so visible? It’s possible to track content pretty much invisibly these days, so this overt display isn’t really necessary, if it was put there by professionals, that is.

Of course, by being this obvious there might be a little bit of psychological warfare at play by whoever put the codes on the screen. Or, indeed, there might be a more benign explanation relating to certain equipment used in the process.

Only time will tell, but it’s safe to say that neither Mayweather nor McGregor will be too worried, having bagged hundreds of millions of dollars in revenue from the showpiece event.

Source: TF, for the latest info on copyright, file-sharing, torrent sites and ANONYMOUS VPN services.

Military Robots as a Nature Analog

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2017/08/military_robots.html

This very interesting essay looks at the future of military robotics and finds many analogs in nature:

Imagine a low-cost drone with the range of a Canada goose, a bird that can cover 1,500 miles in a single day at an average speed of 60 miles per hour. Planet Earth profiled a single flock of snow geese, birds that make similar marathon journeys, albeit slower. The flock of six-pound snow geese was so large it formed a sky-darkening cloud 12 miles long. How would an aircraft carrier battlegroup respond to an attack from millions of aerial kamikaze explosive drones that, like geese, can fly hundreds of miles? A single aircraft carrier costs billions of dollars, and the United States relies heavily on its ten aircraft carrier strike groups to project power around the globe. But as military robots match more capabilities found in nature, some of the major systems and strategies upon which U.S. national security currently relies — perhaps even the fearsome aircraft carrier strike group — might experience the same sort of technological disruption that the smartphone revolution brought about in the consumer world.

Hunting for life on Mars assisted by high-altitude balloons

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/eclipse-high-altitude-balloons/

Will bacteria-laden high-altitude balloons help us find life on Mars? Today’s eclipse should bring us closer to an answer.

NASA Bacteria Balloons Raspberry Pi HAB Life on Mars

image c/o NASA / Ames Research Center / Tristan Caro

The Eclipse Ballooning Project

Having learned of the Eclipse Ballooning Project set to take place today across the USA, a team at NASA couldn’t miss the opportunity to harness the high-flying project for their own experiments.

NASA Bacteria Balloons Raspberry Pi HAB Life on Mars

The Eclipse Ballooning Project invited students across the USA to aid in the launch of 50+ high-altitude balloons during today’s eclipse. Each balloon is equipped with its own Raspberry Pi and camera for data collection and live video-streaming.

High-altitude ballooning, or HAB as it’s often referred to, has become a popular activity within the Raspberry Pi community. The lightweight nature of the device allows for high ascent, and its Camera Module enables instant visual content collection.

Life on Mars

image c/o Montana State University

The Eclipse Ballooning Project team, headed by Angela Des Jardins of Montana State University, was contacted by Jim Green, Director of Planetary Science at NASA, who hoped to piggyback on the project to run tests on bacteria in the Mars-like conditions the balloons would encounter near space.

Into the stratosphere

At around -35 degrees Fahrenheit, with thinner air and harsher ultraviolet radiation, the conditions in the upper part of the earth’s stratosphere are comparable to those on the surface of Mars. And during the eclipse, the moon will block some UV rays, making the environment in our stratosphere even more similar to the martian oneideal for NASA’s experiment.

So the students taking part in the Eclipse Ballooning Project could help the scientists out, NASA sent them some small metal tags.

NASA Bacteria Balloons Raspberry Pi HAB Life on Mars

These tags contain samples of a kind of bacterium known as Paenibacillus xerothermodurans. Upon their return to ground, the bacteria will be tested to see whether and how the high-altitude conditions affected them.

Life on Mars

Paenibacillus xerothermodurans is one of the most resilient bacterial species we know. The team at NASA wants to discover how the bacteria react to their flight in order to learn more about whether life on Mars could possibly exist. If the low temperature, UV rays, and air conditions cause the bacteria to mutate or indeed die, we can be pretty sure that the existence of living organisms on the surface of Mars is very unlikely.

Life on Mars

What happens to the bacteria on the spacecraft and rovers we send to space? This experiment should provide some answers.

The eclipse

If you’re in the US, you might have a chance to witness the full solar eclipse today. And if you’re planning to watch, please make sure to take all precautionary measures. In a nutshell, don’t look directly at the sun. Not today, not ever.

If you’re in the UK, you can observe a partial eclipse, if the clouds decide to vanish. And again, take note of safety measures so you don’t damage your eyes.

Life on Mars

You can also watch a live-stream of the eclipse via the NASA website.

If you’ve created an eclipse-viewing Raspberry Pi project, make sure to share it with us. And while we’re talking about eclipses and balloons, check here for our coverage of the 2015 balloon launches coinciding with the UK’s partial eclipse.

The post Hunting for life on Mars assisted by high-altitude balloons appeared first on Raspberry Pi.

Hacking Slot Machines by Reverse-Engineering the Random Number Generators

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2017/08/hacking_slot_ma.html

Interesting story:

The venture is built on Alex’s talent for reverse engineering the algorithms — known as pseudorandom number generators, or PRNGs — that govern how slot machine games behave. Armed with this knowledge, he can predict when certain games are likeliest to spit out money­insight that he shares with a legion of field agents who do the organization’s grunt work.

These agents roam casinos from Poland to Macau to Peru in search of slots whose PRNGs have been deciphered by Alex. They use phones to record video of a vulnerable machine in action, then transmit the footage to an office in St. Petersburg. There, Alex and his assistants analyze the video to determine when the games’ odds will briefly tilt against the house. They then send timing data to a custom app on an agent’s phone; this data causes the phones to vibrate a split second before the agent should press the “Spin” button. By using these cues to beat slots in multiple casinos, a four-person team can earn more than $250,000 a week.

It’s an interesting article; I have no idea how much of it is true.

The sad part is that the slot-machine vulnerability is so easy to fix. Although the article says that “writing such algorithms requires tremendous mathematical skill,” it’s really only true that designing the algorithms requires that skill. Using any secure encryption algorithm or hash function as a PRNG is trivially easy. And there’s no reason why the system can’t be designed with a real RNG. There is some randomness in the system somewhere, and it can be added into the mix as well. The programmers can use a well-designed algorithm, like my own Fortuna, but even something less well-thought-out is likely to foil this attack.