package main import ( "fmt" "os" "syscall" tracer "github.com/criyle/go-judger/tracer" libseccomp "github.com/seccomp/libseccomp-golang" ) func softBanSyscall(ctx *tracer.Context) tracer.TraceAction { ctx.SetReturnValue(-int(syscall.EACCES)) return tracer.TraceBan } func getFileMode(flags uint) string { switch flags & syscall.O_ACCMODE { case syscall.O_RDONLY: return "r " case syscall.O_WRONLY: return "w " case syscall.O_RDWR: return "wr" default: return "??" } } func getHandle(t *tracer.Tracer, pType string, addRead []string, addWrite []string, allowProc bool) func(ctx *tracer.Context) tracer.TraceAction { var ( fs = newFileSets() sc = newSyscallCounter() showDetails = t.ShowDetails ) inifConf(t, &fs, &sc, pType, addRead, addWrite, allowProc) print := func(v ...interface{}) { if showDetails { fmt.Fprintln(os.Stderr, v...) } } onDgsFileDetect := func(ctx *tracer.Context, name string) tracer.TraceAction { if fs.isSoftBanFile(&name) { return softBanSyscall(ctx) } return tracer.TraceKill } checkOpen := func(ctx *tracer.Context, addr uint, flags uint) tracer.TraceAction { fn := ctx.GetString(uintptr(addr)) isReadOnly := (flags&syscall.O_ACCMODE == syscall.O_RDONLY) && (flags&syscall.O_CREAT == 0) && (flags&syscall.O_EXCL == 0) && (flags&syscall.O_TRUNC == 0) print("open: ", fn, getFileMode(flags)) if isReadOnly { if realPath(fn) != "" && !fs.isReadableFile(&fn) { return onDgsFileDetect(ctx, fn) } } else { if realPath(fn) != "" && !fs.isWritableFile(&fn) { return onDgsFileDetect(ctx, fn) } } return tracer.TraceAllow } checkRead := func(ctx *tracer.Context, addr uint) tracer.TraceAction { fn := ctx.GetString(uintptr(addr)) print("check read: ", fn) if !fs.isReadableFile(&fn) { return onDgsFileDetect(ctx, fn) } return tracer.TraceAllow } checkWrite := func(ctx *tracer.Context, addr uint) tracer.TraceAction { fn := ctx.GetString(uintptr(addr)) print("check write: ", fn) if !fs.isWritableFile(&fn) { return onDgsFileDetect(ctx, fn) } return tracer.TraceAllow } checkStat := func(ctx *tracer.Context, addr uint) tracer.TraceAction { fn := ctx.GetString(uintptr(addr)) print("check stat: ", fn) if !fs.isStatableFile(&fn) { return onDgsFileDetect(ctx, fn) } return tracer.TraceAllow } return func(ctx *tracer.Context) tracer.TraceAction { syscallNo := ctx.SyscallNo() syscallName, err := libseccomp.ScmpSyscall(syscallNo).GetName() print("syscall: ", syscallNo, syscallName, err) switch syscallName { case "open": return checkOpen(ctx, ctx.Arg0(), ctx.Arg1()) case "openat": return checkOpen(ctx, ctx.Arg1(), ctx.Arg2()) case "readlink": return checkRead(ctx, ctx.Arg0()) case "readlinkat": return checkRead(ctx, ctx.Arg1()) case "unlink": return checkWrite(ctx, ctx.Arg0()) case "unlinkat": return checkWrite(ctx, ctx.Arg1()) case "access": return checkStat(ctx, ctx.Arg0()) case "stat": return checkStat(ctx, ctx.Arg0()) case "lstat": return checkStat(ctx, ctx.Arg0()) case "execve": return checkRead(ctx, ctx.Arg0()) case "chmod": return checkWrite(ctx, ctx.Arg0()) case "rename": return checkWrite(ctx, ctx.Arg0()) default: // if it is traced, then try to count syscall if inside, allow := sc.check(syscallName); !allow { return tracer.TraceKill } else if !inside { // if it is traced but not counted, it should be soft banned return softBanSyscall(ctx) } } return tracer.TraceAllow } }