go-sandbox/README.md
2019-08-08 22:34:34 -07:00

2.9 KiB

go-judger

Under developing.

Goal is to reimplement uoj-judger/run_program in GO language using libseccomp.

Install:

  • install go compiler: apt install golang-go
  • install libseccomp-dev: apt install libseccomp-dev
  • install: go install github.com/criyle/go-judger/...

Features (same as uoj-judger/run_program):

  1. Restricted computing resource: Time & Memory (Stack) & Output
  2. Restricted syscall access (by libseccomp & ptrace)
  3. Restricted file access (read & write & access & exec)

New Features:

  1. Percise resource limits (s -> ms, mb -> kb)
  2. More architectures (arm32, arm64, x86)
  3. Allow multiple traced programs in different threads
  4. Allow pipes as input / output files
  5. Use Linux Namespace to isolate file access (elimilate ptrace)
  6. Use Linux Control Groups to limit & acct CPU & memory (elimilate wait4.rusage)
  7. Container tech with execveat memfd, sethostname, setdomainname
  8. Pre-fork container deamons to run programs inside

Default file access action:

  • check file read / write: open, openat
  • check file read: readlink, readlinkat
  • check file write: unlink, unlinkat, chmod, rename
  • check file access: stat, lstat, access, faccessat
  • check file exec: execveat

Packages:

  • seccomp: provides utility function that wrappers libseccomp
  • forkexec: fork-exec provides mount, unshare, ptrace, seccomp, capset before exec
  • memfd: read regular file and creates a seaed memfd for its contents
  • unixsocket: send / recv oob msg from a unix socket
  • cgroup: creates cgroup directories and collects resource usage / limits
  • deamon: creates pre-forked container to run programs inside
  • tracer: ptrace tracer and provides syscall trap filter context
  • runprogram: wrapper to call forkexec and trecer
  • rununshared: wrapper to call forkexec and unshared namespaces
  • runconfig: defines arch & language specified trace condition for seccomp and ptrace
  • types: general runtime specs
    • mount: provides utility function that wrappers mount syscall
    • rlimit: provides utility function that defines rlimit syscall
    • specs: provides general res / result data structures

Executable:

  • run_program: safely run program by unshare / ptrace / pre-forked containers

Configuations:

  • run_program/config.go: all configs toward running specs

Benchmarks (docker desktop amd64 / native arm64):

  • 1ms / 2ms: fork, unshare pid / user / cgroup
  • 4ms / 8ms: run inside pre-forked container
  • 50ms / 25ms: unshare ipc / mount
  • 100ms / 44ms: unshare pid & user & cgroup & mount & pivot root
  • 400ms / 63ms: unshare net
  • 800ms / 170ms: unshare all
  • 880ms / 170ms: unshare all & pivot root

It seems unshare net or ipc takes time, maybe limits action by seccomp instead. Pre-forked container also saves time for container creation / cleanup.

TODO: