12 ms·

Unfork: The Inverse of Fork(2)

150 points by tta 5y ago

formerly_proven 5y ago
> Dynamic binary analysis and instrumentation of applications with built-in integrity checks. As far as I know process_vm_readv isn't even detectable [...] So... cheat development? Coincidentally, the "manifesto" behind the bot invasion in Team Fortress 2: https://c-v.sh/unsownriddles https://c-v.sh/unsownriddles At first I thought that has to be straight trolling ("Educate yourself about GNU/Linux"!), but I'm not so sure it is: https://github.com/nullworks/cathook https://github.com/nullworks/cathook Either way, deeply weird to put Linux (ehm, "GNU/Linux") into the headline of your cheat that's literally only designed to make a game unplayable (https://github.com/nullworks/cathook/issues/1480 https://github.com/nullworks/cathook/issues/1480).
- somebodythere 5y ago
  Or, DRM removal, or, malware analysis, or...
  - cestith 5y ago
    Or forward porting your old software for which you've somehow lost the source. Or helping reverse some abandoned commercial code to write a compatible replacement. Or help verifying you're getting from the compiler what you expected from your source. Probably half a dozen other things neither of us have thought up. This is the sort of software smart people can use for fresh and novel things the designer never even intended.
- swinglock 5y ago
  It's deep trolling, as it doesn't even do Linux any favors. Alternative slogan; "Port your game to GNU/Linux! Gain less than 1% players and no revenue while increasing your maintenance cost in ways you couldn't imagine. Try to reverse the decision without too much bad PR or lose all your established customers, then watch it all die. Educate yourself about GNU/Linux!".
  - zxzax 5y ago
    Just from doing a little bit of research, the problem there seems to be that the netcode in that game is pretty old and has a lot of unfixed bugs that trolls are taking advantage of, not really anything to do with Linux. If they don't want to pay people to fix it, maybe they can open source the server code so someone else can fix the bugs?
  - notriddle 5y ago
    Valve probably ported their stuff to Linux as a hedge against the Windows and Mac App Stores. It barely even matters if people use it or not; they just need a way to convince Microsoft and Apple that breaking Steam isn't in their best interests.
    - mhh__ 5y ago
      Could also be a niche revenue stream in future if they starting build it now: A few old games (and modern ones) run better on Linux via Valve's work than they do windows, that mean's Valve can still sell them.
touisteur 5y ago
That's very interesting. Userfaultfd opened a lot of features in Linux. When I saw 'unfork' I thought 'someone found out how to replace the current process with a child process that was a older snapshot'. Any idea on how to do this? Like 'OK I did something wrong, let me back up a bit, kill me, replace me with my child x and refather every other one of my children processes to child x and gooo'.
- agumonkey 5y ago
  ProlOS
  - touisteur 5y ago
    OK I really tried but my Googlefu seems lacking. Any pointer, pretty please?
    - agumonkey 5y ago
      Oh it was mostly a pun blending prolog like backtracking at the os-process level.
      - touisteur 5y ago
        I figured. I went down the rabbit hole, prolo, and prolog and hoped it wasn't a pun :-) yes I think backtracking as a general OS mechanism. Since the kernel already knows which pages differ between both processes, and could 'just' plug back any socket, file, shm, pipe 'as is' when 'restoring'. All the state is know to the OS! Maybe something with ebpf in twelve years...
        agumonkey 5y ago
        and live exploratory debugging when your fs fails
        touisteur 5y ago
sys_64738 5y ago
I thought this might be something like thread.join() but I don't get it otherwise.
- touisteur 5y ago
  I think it's like getting all the updates after you forked a process. You (child) get notified of all the cow/vm changes (in your parent) and they get merged into your process space? Or is the opposite? :-)
saagarjha 5y ago
Discussion from when it came out: https://news.ycombinator.com/item?id=21394678 https://news.ycombinator.com/item?id=21394678

150 points by tta 5y ago

> Dynamic binary analysis and instrumentation of applications with built-in integrity checks. As far as I know process_vm_readv isn't even detectable [...] So... cheat development? Coincidentally, the "manifesto" behind the bot invasion in Team Fortress 2: https://c-v.sh/unsownriddles https://c-v.sh/unsownriddles At first I thought that has to be straight trolling ("Educate yourself about GNU/Linux"!), but I'm not so sure it is: https://github.com/nullworks/cathook https://github.com/nullworks/cathook Either way, deeply weird to put Linux (ehm, "GNU/Linux") into the headline of your cheat that's literally only designed to make a game unplayable (https://github.com/nullworks/cathook/issues/1480 https://github.com/nullworks/cathook/issues/1480).

somebodythere 5y ago
Or, DRM removal, or, malware analysis, or...
- cestith 5y ago
  Or forward porting your old software for which you've somehow lost the source. Or helping reverse some abandoned commercial code to write a compatible replacement. Or help verifying you're getting from the compiler what you expected from your source. Probably half a dozen other things neither of us have thought up. This is the sort of software smart people can use for fresh and novel things the designer never even intended.
swinglock 5y ago
It's deep trolling, as it doesn't even do Linux any favors. Alternative slogan; "Port your game to GNU/Linux! Gain less than 1% players and no revenue while increasing your maintenance cost in ways you couldn't imagine. Try to reverse the decision without too much bad PR or lose all your established customers, then watch it all die. Educate yourself about GNU/Linux!".
- zxzax 5y ago
  Just from doing a little bit of research, the problem there seems to be that the netcode in that game is pretty old and has a lot of unfixed bugs that trolls are taking advantage of, not really anything to do with Linux. If they don't want to pay people to fix it, maybe they can open source the server code so someone else can fix the bugs?
- notriddle 5y ago
  Valve probably ported their stuff to Linux as a hedge against the Windows and Mac App Stores. It barely even matters if people use it or not; they just need a way to convince Microsoft and Apple that breaking Steam isn't in their best interests.
  - mhh__ 5y ago
    Could also be a niche revenue stream in future if they starting build it now: A few old games (and modern ones) run better on Linux via Valve's work than they do windows, that mean's Valve can still sell them.

touisteur 5y ago

That's very interesting. Userfaultfd opened a lot of features in Linux. When I saw 'unfork' I thought 'someone found out how to replace the current process with a child process that was a older snapshot'. Any idea on how to do this? Like 'OK I did something wrong, let me back up a bit, kill me, replace me with my child x and refather every other one of my children processes to child x and gooo'.

agumonkey 5y ago
ProlOS
- touisteur 5y ago
  OK I really tried but my Googlefu seems lacking. Any pointer, pretty please?
  - agumonkey 5y ago
    Oh it was mostly a pun blending prolog like backtracking at the os-process level.
    - touisteur 5y ago
      I figured. I went down the rabbit hole, prolo, and prolog and hoped it wasn't a pun :-) yes I think backtracking as a general OS mechanism. Since the kernel already knows which pages differ between both processes, and could 'just' plug back any socket, file, shm, pipe 'as is' when 'restoring'. All the state is know to the OS! Maybe something with ebpf in twelve years...
      - agumonkey 5y ago
        and live exploratory debugging when your fs fails
        touisteur 5y ago

sys_64738 5y ago

I thought this might be something like thread.join() but I don't get it otherwise.

touisteur 5y ago
I think it's like getting all the updates after you forked a process. You (child) get notified of all the cow/vm changes (in your parent) and they get merged into your process space? Or is the opposite? :-)

saagarjha 5y ago

Discussion from when it came out: https://news.ycombinator.com/item?id=21394678 https://news.ycombinator.com/item?id=21394678