# go-sandbox Original goal is to reimplement [uoj-judger/run_program](https://github.com/vfleaking/uoj) in GO language using [libseccomp](https://github.com/seccomp/libseccomp-golang). As technology grows, it also implements new technologies including Linux namespace & cgroup. ## Install - install go compiler: `apt install golang-go` - install libseccomp-dev: `apt install libseccomp-dev` - install: `go install github.com/criyle/go-sandbox/...` ## Technologies ### libseccomp + ptrace (improved UOJ sandbox) 1. Restricted computing resource by POSIX rlimit: Time & Memory (Stack) & Output 2. Restricted syscall access (by libseccomp & ptrace) 3. Restricted file access (read & write & access & exec). Evaluated by UOJ FileSet Improvements: 1. Precise 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 Default file access syscall check: - 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` ### linux namespace + cgroup 1. Unshare & bind mount rootfs based on hostfs (elimilated ptrace) 2. Use Linux Control Groups to limit & acct CPU & memory (elimilate wait4.rusage) 3. Container tech with execveat memfd, sethostname, setdomainname ### pre-forked container 1. Pre-fork container deamons to run programs inside 2. Unix socket to pass fd inside / outside ## 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 ## Configurations - 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. ```bash $ go test -bench . -benchtime 10s goos: linux goarch: amd64 pkg: github.com/criyle/go-sandbox/forkexec BenchmarkSimpleFork-4 10000 1106064 ns/op BenchmarkUnsharePid-4 10000 1367824 ns/op BenchmarkUnshareUser-4 10000 1311523 ns/op BenchmarkUnshareUts-4 10000 1140427 ns/op BenchmarkUnshareCgroup-4 10000 1112713 ns/op BenchmarkUnshareIpc-4 300 58730786 ns/op BenchmarkUnshareMount-4 300 55540758 ns/op BenchmarkUnshareNet-4 100 396957720 ns/op BenchmarkFastUnshareMountPivot-4 100 114364585 ns/op BenchmarkUnshareAll-4 100 851014031 ns/op BenchmarkUnshareMountPivot-4 20 901204445 ns/op PASS ok github.com/criyle/go-sandbox/forkexec 262.112s ``` ## TODO