diff options
Diffstat (limited to 'python/runner')
| -rwxr-xr-x | python/runner/interpreter.py | 87 | ||||
| -rw-r--r-- | python/runner/sandbox.c | 47 | ||||
| -rw-r--r-- | python/runner/terminator.c | 32 |
3 files changed, 166 insertions, 0 deletions
diff --git a/python/runner/interpreter.py b/python/runner/interpreter.py new file mode 100755 index 0000000..dae4d59 --- /dev/null +++ b/python/runner/interpreter.py @@ -0,0 +1,87 @@ +#!/usr/bin/python3 + +import code +import sys + +import seccomp + +f = seccomp.SyscallFilter(defaction=seccomp.KILL) +# Necessary for Python. +f.add_rule(seccomp.ALLOW, "brk") +f.add_rule(seccomp.ALLOW, "exit_group") +f.add_rule(seccomp.ALLOW, "ioctl") +f.add_rule(seccomp.ALLOW, "mmap") +f.add_rule(seccomp.ALLOW, "munmap") +f.add_rule(seccomp.ALLOW, "rt_sigaction") +f.add_rule(seccomp.ALLOW, "rt_sigreturn") + +# Mostly harmless. +f.add_rule(seccomp.ALLOW, "mprotect") + +# Allow reading from stdin and writing to stdout/stderr. +f.add_rule(seccomp.ALLOW, "read", seccomp.Arg(0, seccomp.EQ, sys.stdin.fileno())) +f.add_rule(seccomp.ALLOW, "write", seccomp.Arg(0, seccomp.EQ, sys.stdout.fileno())) +f.add_rule(seccomp.ALLOW, "write", seccomp.Arg(0, seccomp.EQ, sys.stderr.fileno())) + +# Needed for finding source code for exceptions. +f.add_rule(seccomp.ALLOW, "stat") +f.add_rule(seccomp.ALLOW, "open", seccomp.Arg(1, seccomp.MASKED_EQ, 0x3, 0)) # O_RDONLY +f.add_rule(seccomp.ALLOW, "close") +f.add_rule(seccomp.ALLOW, "read") +f.add_rule(seccomp.ALLOW, "fstat") +f.add_rule(seccomp.ALLOW, "lseek") +f.add_rule(seccomp.ALLOW, "fcntl") + +# Needed for help(). +f.add_rule(seccomp.ALLOW, "openat", seccomp.Arg(2, seccomp.MASKED_EQ, 0x3, 0)) # O_RDONLY +f.add_rule(seccomp.ALLOW, "getdents") +f.add_rule(seccomp.ALLOW, "getrlimit", seccomp.Arg(0, seccomp.EQ, 3)) # RLIMIT_STACK +f.add_rule(seccomp.ALLOW, "getrlimit", seccomp.Arg(0, seccomp.EQ, 7)) # RLIMIT_NOFILE + +# Needed for code.InteractiveConsole. +f.add_rule(seccomp.ALLOW, "access") +f.add_rule(seccomp.ALLOW, "select") +f.load() + +class MyConsole(code.InteractiveConsole): + def interact(self, banner=None): + if banner is not None: + self.write('{}\n'.format(banner)) + + buffer = [] + prompt = '>>> ' + while True: + try: + line = input(prompt) + # Assume we are running the user's program; silence the prompt. + if line == 'exec("""\\': + self.write('<run>\n') + prompt = '' + + buffer.append(line) + source = '\n'.join(buffer) + more = self.runsource(source) + if more: + if prompt: + prompt = '... ' + else: + prompt = '>>> ' + buffer = [] + except KeyboardInterrupt: + prompt = '>>> ' + buffer = [] + self.write('\n') + except EOFError: + break + + def runcode(self, code): + try: + exec(code, self.locals) + except KeyboardInterrupt: + # Don't show traceback on SIGINT. + self.write('^C') + raise + except: + self.showtraceback() + +MyConsole().interact() diff --git a/python/runner/sandbox.c b/python/runner/sandbox.c new file mode 100644 index 0000000..12e2720 --- /dev/null +++ b/python/runner/sandbox.c @@ -0,0 +1,47 @@ +#include <fcntl.h> +#include <pwd.h> +#include <stdio.h> +#include <sys/prctl.h> +#include <sys/resource.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <unistd.h> + +int main(int argc, char* argv[]) +{ + if (argc < 3) { + fprintf(stderr, "usage: %s USERNAME FILE\n", argv[0]); + return 1; + } + + // switch user (requires root or "setcap cap_setuid,cap_setgid+ep") + char const* username = argv[1]; + struct passwd const* pw = getpwnam(username); + if (!pw) { + fprintf(stderr, "no such user: %s\n", username); + return 1; + } + int ret = 0; + if ((ret = setuid(pw->pw_uid)) != 0) + fprintf(stderr, "setuid returned %d\n", ret); + if ((ret = setgid(pw->pw_gid)) != 0) + fprintf(stderr, "setgid returned %d\n", ret); + + // limit CPU time to 1 second + struct rlimit const cpu_limit = { .rlim_cur = 1, .rlim_max = 1 }; + if ((ret = setrlimit(RLIMIT_CPU, &cpu_limit)) != 0) + fprintf(stderr, "setrlimit(CPU) returned %d\n", ret); + + // don't allow writing files of any size + struct rlimit const fsize_limit = { .rlim_cur = 0, .rlim_max = 0 }; + if ((ret = setrlimit(RLIMIT_FSIZE, &fsize_limit)) != 0) + fprintf(stderr, "setrlimit(FSIZE) returned %d\n", ret); + + // there will be no fork + struct rlimit const nproc_limit = { .rlim_cur = 0, .rlim_max = 0 }; + if ((ret = setrlimit(RLIMIT_NPROC, &nproc_limit)) != 0) + fprintf(stderr, "setrlimit(NPROC) returned %d\n", ret); + + char* const args[] = { argv[2], (char*)0 }; + return execvp(argv[2], args); +} diff --git a/python/runner/terminator.c b/python/runner/terminator.c new file mode 100644 index 0000000..a994bde --- /dev/null +++ b/python/runner/terminator.c @@ -0,0 +1,32 @@ +#include <pwd.h> +#include <signal.h> +#include <stdio.h> +#include <stdlib.h> +#include <sys/stat.h> +#include <sys/types.h> + +int main(int argc, char* argv[]) +{ + if (argc < 4) { + fprintf(stderr, "usage: %s USERNAME PID SIGNAL\n", argv[0]); + return 1; + } + + // switch user (requires root or "setcap cap_setuid,cap_setgid+ep") + char const* username = argv[1]; + struct passwd const* pw = getpwnam(username); + if (!pw) { + fprintf(stderr, "no such user: %s\n", username); + return 1; + } + int ret = 0; + if ((ret = setuid(pw->pw_uid)) != 0) + fprintf(stderr, "setuid returned %d\n", ret); + if ((ret = setgid(pw->pw_gid)) != 0) + fprintf(stderr, "setgid returned %d\n", ret); + + pid_t pid = atol(argv[2]); + int signum = atoi(argv[3]); + kill(pid, signum); + return 0; +} |