mirror of
https://github.com/criyle/go-sandbox.git
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110 lines
4.2 KiB
Markdown
110 lines
4.2 KiB
Markdown
# go-sandbox
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[](https://godoc.org/github.com/criyle/go-sandbox)
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Original goal was to reimplement [uoj-judger/run_program](https://github.com/vfleaking/uoj) in GO language using [libseccomp](https://github.com/pkg/seccomp/libseccomp-golang). As technology grows, it also implements new technologies including Linux namespace and cgroup.
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## Install
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- install go compiler: `apt install golang-go`
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- install libseccomp-dev: `apt install libseccomp-dev`
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- install: `go install github.com/criyle/go-sandbox/...`
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## Technologies
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### libseccomp + ptrace (improved UOJ sandbox)
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1. Restricted computing resource by POSIX rlimit: Time & Memory (Stack) & Output
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2. Restricted syscall access (by libseccomp & ptrace)
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3. Restricted file access (read & write & access & exec). Evaluated by UOJ FileSet
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Improvements:
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1. Precise resource limits (s -> ms, mb -> kb)
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2. More architectures (arm32, arm64)
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3. Allow multiple traced programs in different threads
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4. Allow pipes as input / output files
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Default file access syscall check:
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- check file read / write: `open`, `openat`
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- check file read: `readlink`, `readlinkat`
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- check file write: `unlink`, `unlinkat`, `chmod`, `rename`
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- check file access: `stat`, `lstat`, `access`, `faccessat`
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- check file exec: `execve`, `execveat`
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### linux namespace + cgroup
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1. Unshare & bind mount rootfs based on hostfs (elimilated ptrace)
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2. Use Linux Control Groups to limit & acct CPU & memory (elimilate wait4.rusage)
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3. Container tech with execveat memfd, sethostname, setdomainname
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### pre-forked container
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1. Pre-fork container daemons to run programs inside
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2. Unix socket to pass fd inside / outside
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## Packages (/pkg)
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- seccomp: provides seccomp type definition
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- libseccomp: provides utility function that wrappers libseccomp
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- forkexec: fork-exec provides mount, unshare, ptrace, seccomp, capset before exec
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- memfd: read regular file and creates a seaed memfd for its contents
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- unixsocket: send / recv oob msg from a unix socket
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- cgroup: creates cgroup directories and collects resource usage / limits
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- mount: provides utility function that wrappers mount syscall
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- rlimit: provides utility function that defines rlimit syscall
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- pipe: provides wrapper to collect all written content through pipe
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## Packages
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- config: defines arch & language specified trace condition for ptrace runner from UOJ
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- daemon: creates pre-forked container to run programs inside
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- runner: interface to run program
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- ptrace: wrapper to call forkexec and ptracer
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- filehandler: an implementation of UOJ file set
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- unshare: wrapper to call forkexec and unshared namespaces
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- ptracer: ptrace tracer and provides syscall trap filter context
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- types: provides general res / result data structures
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## Executable
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- runprog: safely run program by unshare / ptrace / pre-forked containers
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## Configurations
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- config/config.go: all configs toward running specs (similar to UOJ)
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## Benchmarks (docker desktop amd64 / native arm64)
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- 1ms / 2ms: fork, unshare pid / user / cgroup
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- 4ms / 8ms: run inside pre-forked container
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- 50ms / 25ms: unshare ipc / mount
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- 100ms / 44ms: unshare pid & user & cgroup & mount & pivot root
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- 400ms / 63ms: unshare net
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- 800ms / 170ms: unshare all
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- 880ms / 170ms: unshare all & pivot root
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It seems unshare net or ipc takes time, maybe limits action by seccomp instead.
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Pre-forked container also saves time for container creation / cleanup.
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```bash
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$ go test -bench . -benchtime 10s
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goos: linux
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goarch: amd64
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pkg: github.com/criyle/go-sandbox/pkg/forkexec
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BenchmarkSimpleFork-4 12789 870486 ns/op
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BenchmarkUnsharePid-4 13172 917304 ns/op
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BenchmarkUnshareUser-4 13148 927952 ns/op
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BenchmarkUnshareUts-4 13170 884606 ns/op
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BenchmarkUnshareCgroup-4 13650 895186 ns/op
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BenchmarkUnshareIpc-4 196 66418708 ns/op
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BenchmarkUnshareMount-4 243 46957682 ns/op
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BenchmarkUnshareNet-4 100 411869776 ns/op
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BenchmarkFastUnshareMountPivot-4 120 107310917 ns/op
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BenchmarkUnshareAll-4 100 837352275 ns/op
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BenchmarkUnshareMountPivot-4 12 913099234 ns/op
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PASS
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ok github.com/criyle/go-sandbox/pkg/forkexec 300.744s
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```
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