| /* Authors: Gregory P. Smith & Jeffrey Yasskin */ |
| #include "Python.h" |
| #include "pycore_fileutils.h" |
| #if defined(HAVE_PIPE2) && !defined(_GNU_SOURCE) |
| # define _GNU_SOURCE |
| #endif |
| #include <unistd.h> |
| #include <fcntl.h> |
| #ifdef HAVE_SYS_TYPES_H |
| #include <sys/types.h> |
| #endif |
| #if defined(HAVE_SYS_STAT_H) |
| #include <sys/stat.h> |
| #endif |
| #ifdef HAVE_SYS_SYSCALL_H |
| #include <sys/syscall.h> |
| #endif |
| #if defined(HAVE_SYS_RESOURCE_H) |
| #include <sys/resource.h> |
| #endif |
| #ifdef HAVE_DIRENT_H |
| #include <dirent.h> |
| #endif |
| #ifdef HAVE_GRP_H |
| #include <grp.h> |
| #endif /* HAVE_GRP_H */ |
| |
| #include "posixmodule.h" |
| |
| #ifdef _Py_MEMORY_SANITIZER |
| # include <sanitizer/msan_interface.h> |
| #endif |
| |
| #if defined(__ANDROID__) && __ANDROID_API__ < 21 && !defined(SYS_getdents64) |
| # include <sys/linux-syscalls.h> |
| # define SYS_getdents64 __NR_getdents64 |
| #endif |
| |
| #if defined(__linux__) && defined(HAVE_VFORK) && defined(HAVE_SIGNAL_H) && \ |
| defined(HAVE_PTHREAD_SIGMASK) && !defined(HAVE_BROKEN_PTHREAD_SIGMASK) |
| /* If this is ever expanded to non-Linux platforms, verify what calls are |
| * allowed after vfork(). Ex: setsid() may be disallowed on macOS? */ |
| # include <signal.h> |
| # define VFORK_USABLE 1 |
| #endif |
| |
| #if defined(__sun) && defined(__SVR4) |
| /* readdir64 is used to work around Solaris 9 bug 6395699. */ |
| # define readdir readdir64 |
| # define dirent dirent64 |
| # if !defined(HAVE_DIRFD) |
| /* Some versions of Solaris lack dirfd(). */ |
| # define dirfd(dirp) ((dirp)->dd_fd) |
| # define HAVE_DIRFD |
| # endif |
| #endif |
| |
| #if defined(__FreeBSD__) || (defined(__APPLE__) && defined(__MACH__)) || defined(__DragonFly__) |
| # define FD_DIR "/dev/fd" |
| #else |
| # define FD_DIR "/proc/self/fd" |
| #endif |
| |
| #ifdef NGROUPS_MAX |
| #define MAX_GROUPS NGROUPS_MAX |
| #else |
| #define MAX_GROUPS 64 |
| #endif |
| |
| #define POSIX_CALL(call) do { if ((call) == -1) goto error; } while (0) |
| |
| typedef struct { |
| PyObject* disable; |
| PyObject* enable; |
| PyObject* isenabled; |
| } _posixsubprocessstate; |
| |
| static struct PyModuleDef _posixsubprocessmodule; |
| |
| static inline _posixsubprocessstate* |
| get_posixsubprocess_state(PyObject *module) |
| { |
| void *state = PyModule_GetState(module); |
| assert(state != NULL); |
| return (_posixsubprocessstate *)state; |
| } |
| |
| /* If gc was disabled, call gc.enable(). Ignore errors. */ |
| static void |
| _enable_gc(int need_to_reenable_gc, PyObject *gc_module, _posixsubprocessstate *state) |
| { |
| PyObject *result; |
| PyObject *exctype, *val, *tb; |
| |
| if (need_to_reenable_gc) { |
| PyErr_Fetch(&exctype, &val, &tb); |
| result = PyObject_CallMethodNoArgs( |
| gc_module, state->enable); |
| if (result == NULL) { |
| /* We might have created a child process at this point, we |
| * we have no good way to handle a failure to reenable GC |
| * and return information about the child process. */ |
| PyErr_Print(); |
| } |
| Py_XDECREF(result); |
| if (exctype != NULL) { |
| PyErr_Restore(exctype, val, tb); |
| } |
| } |
| } |
| |
| |
| /* Convert ASCII to a positive int, no libc call. no overflow. -1 on error. */ |
| static int |
| _pos_int_from_ascii(const char *name) |
| { |
| int num = 0; |
| while (*name >= '0' && *name <= '9') { |
| num = num * 10 + (*name - '0'); |
| ++name; |
| } |
| if (*name) |
| return -1; /* Non digit found, not a number. */ |
| return num; |
| } |
| |
| |
| #if defined(__FreeBSD__) || defined(__DragonFly__) |
| /* When /dev/fd isn't mounted it is often a static directory populated |
| * with 0 1 2 or entries for 0 .. 63 on FreeBSD, NetBSD, OpenBSD and DragonFlyBSD. |
| * NetBSD and OpenBSD have a /proc fs available (though not necessarily |
| * mounted) and do not have fdescfs for /dev/fd. MacOS X has a devfs |
| * that properly supports /dev/fd. |
| */ |
| static int |
| _is_fdescfs_mounted_on_dev_fd(void) |
| { |
| struct stat dev_stat; |
| struct stat dev_fd_stat; |
| if (stat("/dev", &dev_stat) != 0) |
| return 0; |
| if (stat(FD_DIR, &dev_fd_stat) != 0) |
| return 0; |
| if (dev_stat.st_dev == dev_fd_stat.st_dev) |
| return 0; /* / == /dev == /dev/fd means it is static. #fail */ |
| return 1; |
| } |
| #endif |
| |
| |
| /* Returns 1 if there is a problem with fd_sequence, 0 otherwise. */ |
| static int |
| _sanity_check_python_fd_sequence(PyObject *fd_sequence) |
| { |
| Py_ssize_t seq_idx; |
| long prev_fd = -1; |
| for (seq_idx = 0; seq_idx < PyTuple_GET_SIZE(fd_sequence); ++seq_idx) { |
| PyObject* py_fd = PyTuple_GET_ITEM(fd_sequence, seq_idx); |
| long iter_fd; |
| if (!PyLong_Check(py_fd)) { |
| return 1; |
| } |
| iter_fd = PyLong_AsLong(py_fd); |
| if (iter_fd < 0 || iter_fd <= prev_fd || iter_fd > INT_MAX) { |
| /* Negative, overflow, unsorted, too big for a fd. */ |
| return 1; |
| } |
| prev_fd = iter_fd; |
| } |
| return 0; |
| } |
| |
| |
| /* Is fd found in the sorted Python Sequence? */ |
| static int |
| _is_fd_in_sorted_fd_sequence(int fd, PyObject *fd_sequence) |
| { |
| /* Binary search. */ |
| Py_ssize_t search_min = 0; |
| Py_ssize_t search_max = PyTuple_GET_SIZE(fd_sequence) - 1; |
| if (search_max < 0) |
| return 0; |
| do { |
| long middle = (search_min + search_max) / 2; |
| long middle_fd = PyLong_AsLong(PyTuple_GET_ITEM(fd_sequence, middle)); |
| if (fd == middle_fd) |
| return 1; |
| if (fd > middle_fd) |
| search_min = middle + 1; |
| else |
| search_max = middle - 1; |
| } while (search_min <= search_max); |
| return 0; |
| } |
| |
| static int |
| make_inheritable(PyObject *py_fds_to_keep, int errpipe_write) |
| { |
| Py_ssize_t i, len; |
| |
| len = PyTuple_GET_SIZE(py_fds_to_keep); |
| for (i = 0; i < len; ++i) { |
| PyObject* fdobj = PyTuple_GET_ITEM(py_fds_to_keep, i); |
| long fd = PyLong_AsLong(fdobj); |
| assert(!PyErr_Occurred()); |
| assert(0 <= fd && fd <= INT_MAX); |
| if (fd == errpipe_write) { |
| /* errpipe_write is part of py_fds_to_keep. It must be closed at |
| exec(), but kept open in the child process until exec() is |
| called. */ |
| continue; |
| } |
| if (_Py_set_inheritable_async_safe((int)fd, 1, NULL) < 0) |
| return -1; |
| } |
| return 0; |
| } |
| |
| |
| /* Get the maximum file descriptor that could be opened by this process. |
| * This function is async signal safe for use between fork() and exec(). |
| */ |
| static long |
| safe_get_max_fd(void) |
| { |
| long local_max_fd; |
| #if defined(__NetBSD__) |
| local_max_fd = fcntl(0, F_MAXFD); |
| if (local_max_fd >= 0) |
| return local_max_fd; |
| #endif |
| #if defined(HAVE_SYS_RESOURCE_H) && defined(__OpenBSD__) |
| struct rlimit rl; |
| /* Not on the POSIX async signal safe functions list but likely |
| * safe. TODO - Someone should audit OpenBSD to make sure. */ |
| if (getrlimit(RLIMIT_NOFILE, &rl) >= 0) |
| return (long) rl.rlim_max; |
| #endif |
| #ifdef _SC_OPEN_MAX |
| local_max_fd = sysconf(_SC_OPEN_MAX); |
| if (local_max_fd == -1) |
| #endif |
| local_max_fd = 256; /* Matches legacy Lib/subprocess.py behavior. */ |
| return local_max_fd; |
| } |
| |
| |
| /* Close all file descriptors in the range from start_fd and higher |
| * except for those in py_fds_to_keep. If the range defined by |
| * [start_fd, safe_get_max_fd()) is large this will take a long |
| * time as it calls close() on EVERY possible fd. |
| * |
| * It isn't possible to know for sure what the max fd to go up to |
| * is for processes with the capability of raising their maximum. |
| */ |
| static void |
| _close_fds_by_brute_force(long start_fd, PyObject *py_fds_to_keep) |
| { |
| long end_fd = safe_get_max_fd(); |
| Py_ssize_t num_fds_to_keep = PyTuple_GET_SIZE(py_fds_to_keep); |
| Py_ssize_t keep_seq_idx; |
| /* As py_fds_to_keep is sorted we can loop through the list closing |
| * fds in between any in the keep list falling within our range. */ |
| for (keep_seq_idx = 0; keep_seq_idx < num_fds_to_keep; ++keep_seq_idx) { |
| PyObject* py_keep_fd = PyTuple_GET_ITEM(py_fds_to_keep, keep_seq_idx); |
| int keep_fd = PyLong_AsLong(py_keep_fd); |
| if (keep_fd < start_fd) |
| continue; |
| _Py_closerange(start_fd, keep_fd - 1); |
| start_fd = keep_fd + 1; |
| } |
| if (start_fd <= end_fd) { |
| _Py_closerange(start_fd, end_fd); |
| } |
| } |
| |
| |
| #if defined(__linux__) && defined(HAVE_SYS_SYSCALL_H) |
| /* It doesn't matter if d_name has room for NAME_MAX chars; we're using this |
| * only to read a directory of short file descriptor number names. The kernel |
| * will return an error if we didn't give it enough space. Highly Unlikely. |
| * This structure is very old and stable: It will not change unless the kernel |
| * chooses to break compatibility with all existing binaries. Highly Unlikely. |
| */ |
| struct linux_dirent64 { |
| unsigned long long d_ino; |
| long long d_off; |
| unsigned short d_reclen; /* Length of this linux_dirent */ |
| unsigned char d_type; |
| char d_name[256]; /* Filename (null-terminated) */ |
| }; |
| |
| /* Close all open file descriptors in the range from start_fd and higher |
| * Do not close any in the sorted py_fds_to_keep list. |
| * |
| * This version is async signal safe as it does not make any unsafe C library |
| * calls, malloc calls or handle any locks. It is _unfortunate_ to be forced |
| * to resort to making a kernel system call directly but this is the ONLY api |
| * available that does no harm. opendir/readdir/closedir perform memory |
| * allocation and locking so while they usually work they are not guaranteed |
| * to (especially if you have replaced your malloc implementation). A version |
| * of this function that uses those can be found in the _maybe_unsafe variant. |
| * |
| * This is Linux specific because that is all I am ready to test it on. It |
| * should be easy to add OS specific dirent or dirent64 structures and modify |
| * it with some cpp #define magic to work on other OSes as well if you want. |
| */ |
| static void |
| _close_open_fds_safe(int start_fd, PyObject* py_fds_to_keep) |
| { |
| int fd_dir_fd; |
| |
| fd_dir_fd = _Py_open_noraise(FD_DIR, O_RDONLY); |
| if (fd_dir_fd == -1) { |
| /* No way to get a list of open fds. */ |
| _close_fds_by_brute_force(start_fd, py_fds_to_keep); |
| return; |
| } else { |
| char buffer[sizeof(struct linux_dirent64)]; |
| int bytes; |
| while ((bytes = syscall(SYS_getdents64, fd_dir_fd, |
| (struct linux_dirent64 *)buffer, |
| sizeof(buffer))) > 0) { |
| struct linux_dirent64 *entry; |
| int offset; |
| #ifdef _Py_MEMORY_SANITIZER |
| __msan_unpoison(buffer, bytes); |
| #endif |
| for (offset = 0; offset < bytes; offset += entry->d_reclen) { |
| int fd; |
| entry = (struct linux_dirent64 *)(buffer + offset); |
| if ((fd = _pos_int_from_ascii(entry->d_name)) < 0) |
| continue; /* Not a number. */ |
| if (fd != fd_dir_fd && fd >= start_fd && |
| !_is_fd_in_sorted_fd_sequence(fd, py_fds_to_keep)) { |
| close(fd); |
| } |
| } |
| } |
| close(fd_dir_fd); |
| } |
| } |
| |
| #define _close_open_fds _close_open_fds_safe |
| |
| #else /* NOT (defined(__linux__) && defined(HAVE_SYS_SYSCALL_H)) */ |
| |
| |
| /* Close all open file descriptors from start_fd and higher. |
| * Do not close any in the sorted py_fds_to_keep tuple. |
| * |
| * This function violates the strict use of async signal safe functions. :( |
| * It calls opendir(), readdir() and closedir(). Of these, the one most |
| * likely to ever cause a problem is opendir() as it performs an internal |
| * malloc(). Practically this should not be a problem. The Java VM makes the |
| * same calls between fork and exec in its own UNIXProcess_md.c implementation. |
| * |
| * readdir_r() is not used because it provides no benefit. It is typically |
| * implemented as readdir() followed by memcpy(). See also: |
| * http://womble.decadent.org.uk/readdir_r-advisory.html |
| */ |
| static void |
| _close_open_fds_maybe_unsafe(long start_fd, PyObject* py_fds_to_keep) |
| { |
| DIR *proc_fd_dir; |
| #ifndef HAVE_DIRFD |
| while (_is_fd_in_sorted_fd_sequence(start_fd, py_fds_to_keep)) { |
| ++start_fd; |
| } |
| /* Close our lowest fd before we call opendir so that it is likely to |
| * reuse that fd otherwise we might close opendir's file descriptor in |
| * our loop. This trick assumes that fd's are allocated on a lowest |
| * available basis. */ |
| close(start_fd); |
| ++start_fd; |
| #endif |
| |
| #if defined(__FreeBSD__) || defined(__DragonFly__) |
| if (!_is_fdescfs_mounted_on_dev_fd()) |
| proc_fd_dir = NULL; |
| else |
| #endif |
| proc_fd_dir = opendir(FD_DIR); |
| if (!proc_fd_dir) { |
| /* No way to get a list of open fds. */ |
| _close_fds_by_brute_force(start_fd, py_fds_to_keep); |
| } else { |
| struct dirent *dir_entry; |
| #ifdef HAVE_DIRFD |
| int fd_used_by_opendir = dirfd(proc_fd_dir); |
| #else |
| int fd_used_by_opendir = start_fd - 1; |
| #endif |
| errno = 0; |
| while ((dir_entry = readdir(proc_fd_dir))) { |
| int fd; |
| if ((fd = _pos_int_from_ascii(dir_entry->d_name)) < 0) |
| continue; /* Not a number. */ |
| if (fd != fd_used_by_opendir && fd >= start_fd && |
| !_is_fd_in_sorted_fd_sequence(fd, py_fds_to_keep)) { |
| close(fd); |
| } |
| errno = 0; |
| } |
| if (errno) { |
| /* readdir error, revert behavior. Highly Unlikely. */ |
| _close_fds_by_brute_force(start_fd, py_fds_to_keep); |
| } |
| closedir(proc_fd_dir); |
| } |
| } |
| |
| #define _close_open_fds _close_open_fds_maybe_unsafe |
| |
| #endif /* else NOT (defined(__linux__) && defined(HAVE_SYS_SYSCALL_H)) */ |
| |
| |
| #ifdef VFORK_USABLE |
| /* Reset dispositions for all signals to SIG_DFL except for ignored |
| * signals. This way we ensure that no signal handlers can run |
| * after we unblock signals in a child created by vfork(). |
| */ |
| static void |
| reset_signal_handlers(const sigset_t *child_sigmask) |
| { |
| struct sigaction sa_dfl = {.sa_handler = SIG_DFL}; |
| for (int sig = 1; sig < _NSIG; sig++) { |
| /* Dispositions for SIGKILL and SIGSTOP can't be changed. */ |
| if (sig == SIGKILL || sig == SIGSTOP) { |
| continue; |
| } |
| |
| /* There is no need to reset the disposition of signals that will |
| * remain blocked across execve() since the kernel will do it. */ |
| if (sigismember(child_sigmask, sig) == 1) { |
| continue; |
| } |
| |
| struct sigaction sa; |
| /* C libraries usually return EINVAL for signals used |
| * internally (e.g. for thread cancellation), so simply |
| * skip errors here. */ |
| if (sigaction(sig, NULL, &sa) == -1) { |
| continue; |
| } |
| |
| /* void *h works as these fields are both pointer types already. */ |
| void *h = (sa.sa_flags & SA_SIGINFO ? (void *)sa.sa_sigaction : |
| (void *)sa.sa_handler); |
| if (h == SIG_IGN || h == SIG_DFL) { |
| continue; |
| } |
| |
| /* This call can't reasonably fail, but if it does, terminating |
| * the child seems to be too harsh, so ignore errors. */ |
| (void) sigaction(sig, &sa_dfl, NULL); |
| } |
| } |
| #endif /* VFORK_USABLE */ |
| |
| |
| /* |
| * This function is code executed in the child process immediately after |
| * (v)fork to set things up and call exec(). |
| * |
| * All of the code in this function must only use async-signal-safe functions, |
| * listed at `man 7 signal` or |
| * http://www.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_04.html. |
| * |
| * This restriction is documented at |
| * http://www.opengroup.org/onlinepubs/009695399/functions/fork.html. |
| * |
| * If this function is called after vfork(), even more care must be taken. |
| * The lack of preparations that C libraries normally take on fork(), |
| * as well as sharing the address space with the parent, might make even |
| * async-signal-safe functions vfork-unsafe. In particular, on Linux, |
| * set*id() and setgroups() library functions must not be called, since |
| * they have to interact with the library-level thread list and send |
| * library-internal signals to implement per-process credentials semantics |
| * required by POSIX but not supported natively on Linux. Another reason to |
| * avoid this family of functions is that sharing an address space between |
| * processes running with different privileges is inherently insecure. |
| * See bpo-35823 for further discussion and references. |
| * |
| * In some C libraries, setrlimit() has the same thread list/signalling |
| * behavior since resource limits were per-thread attributes before |
| * Linux 2.6.10. Musl, as of 1.2.1, is known to have this issue |
| * (https://www.openwall.com/lists/musl/2020/10/15/6). |
| * |
| * If vfork-unsafe functionality is desired after vfork(), consider using |
| * syscall() to obtain it. |
| */ |
| _Py_NO_INLINE static void |
| child_exec(char *const exec_array[], |
| char *const argv[], |
| char *const envp[], |
| const char *cwd, |
| int p2cread, int p2cwrite, |
| int c2pread, int c2pwrite, |
| int errread, int errwrite, |
| int errpipe_read, int errpipe_write, |
| int close_fds, int restore_signals, |
| int call_setsid, |
| int call_setgid, gid_t gid, |
| int call_setgroups, size_t groups_size, const gid_t *groups, |
| int call_setuid, uid_t uid, int child_umask, |
| const void *child_sigmask, |
| PyObject *py_fds_to_keep, |
| PyObject *preexec_fn, |
| PyObject *preexec_fn_args_tuple) |
| { |
| int i, saved_errno, reached_preexec = 0; |
| PyObject *result; |
| const char* err_msg = ""; |
| /* Buffer large enough to hold a hex integer. We can't malloc. */ |
| char hex_errno[sizeof(saved_errno)*2+1]; |
| |
| if (make_inheritable(py_fds_to_keep, errpipe_write) < 0) |
| goto error; |
| |
| /* Close parent's pipe ends. */ |
| if (p2cwrite != -1) |
| POSIX_CALL(close(p2cwrite)); |
| if (c2pread != -1) |
| POSIX_CALL(close(c2pread)); |
| if (errread != -1) |
| POSIX_CALL(close(errread)); |
| POSIX_CALL(close(errpipe_read)); |
| |
| /* When duping fds, if there arises a situation where one of the fds is |
| either 0, 1 or 2, it is possible that it is overwritten (#12607). */ |
| if (c2pwrite == 0) { |
| POSIX_CALL(c2pwrite = dup(c2pwrite)); |
| /* issue32270 */ |
| if (_Py_set_inheritable_async_safe(c2pwrite, 0, NULL) < 0) { |
| goto error; |
| } |
| } |
| while (errwrite == 0 || errwrite == 1) { |
| POSIX_CALL(errwrite = dup(errwrite)); |
| /* issue32270 */ |
| if (_Py_set_inheritable_async_safe(errwrite, 0, NULL) < 0) { |
| goto error; |
| } |
| } |
| |
| /* Dup fds for child. |
| dup2() removes the CLOEXEC flag but we must do it ourselves if dup2() |
| would be a no-op (issue #10806). */ |
| if (p2cread == 0) { |
| if (_Py_set_inheritable_async_safe(p2cread, 1, NULL) < 0) |
| goto error; |
| } |
| else if (p2cread != -1) |
| POSIX_CALL(dup2(p2cread, 0)); /* stdin */ |
| |
| if (c2pwrite == 1) { |
| if (_Py_set_inheritable_async_safe(c2pwrite, 1, NULL) < 0) |
| goto error; |
| } |
| else if (c2pwrite != -1) |
| POSIX_CALL(dup2(c2pwrite, 1)); /* stdout */ |
| |
| if (errwrite == 2) { |
| if (_Py_set_inheritable_async_safe(errwrite, 1, NULL) < 0) |
| goto error; |
| } |
| else if (errwrite != -1) |
| POSIX_CALL(dup2(errwrite, 2)); /* stderr */ |
| |
| /* We no longer manually close p2cread, c2pwrite, and errwrite here as |
| * _close_open_fds takes care when it is not already non-inheritable. */ |
| |
| if (cwd) |
| POSIX_CALL(chdir(cwd)); |
| |
| if (child_umask >= 0) |
| umask(child_umask); /* umask() always succeeds. */ |
| |
| if (restore_signals) |
| _Py_RestoreSignals(); |
| |
| #ifdef VFORK_USABLE |
| if (child_sigmask) { |
| reset_signal_handlers(child_sigmask); |
| if ((errno = pthread_sigmask(SIG_SETMASK, child_sigmask, NULL))) { |
| goto error; |
| } |
| } |
| #endif |
| |
| #ifdef HAVE_SETSID |
| if (call_setsid) |
| POSIX_CALL(setsid()); |
| #endif |
| |
| #ifdef HAVE_SETGROUPS |
| if (call_setgroups) |
| POSIX_CALL(setgroups(groups_size, groups)); |
| #endif /* HAVE_SETGROUPS */ |
| |
| #ifdef HAVE_SETREGID |
| if (call_setgid) |
| POSIX_CALL(setregid(gid, gid)); |
| #endif /* HAVE_SETREGID */ |
| |
| #ifdef HAVE_SETREUID |
| if (call_setuid) |
| POSIX_CALL(setreuid(uid, uid)); |
| #endif /* HAVE_SETREUID */ |
| |
| |
| reached_preexec = 1; |
| if (preexec_fn != Py_None && preexec_fn_args_tuple) { |
| /* This is where the user has asked us to deadlock their program. */ |
| result = PyObject_Call(preexec_fn, preexec_fn_args_tuple, NULL); |
| if (result == NULL) { |
| /* Stringifying the exception or traceback would involve |
| * memory allocation and thus potential for deadlock. |
| * We've already faced potential deadlock by calling back |
| * into Python in the first place, so it probably doesn't |
| * matter but we avoid it to minimize the possibility. */ |
| err_msg = "Exception occurred in preexec_fn."; |
| errno = 0; /* We don't want to report an OSError. */ |
| goto error; |
| } |
| /* Py_DECREF(result); - We're about to exec so why bother? */ |
| } |
| |
| /* close FDs after executing preexec_fn, which might open FDs */ |
| if (close_fds) { |
| /* TODO HP-UX could use pstat_getproc() if anyone cares about it. */ |
| _close_open_fds(3, py_fds_to_keep); |
| } |
| |
| /* This loop matches the Lib/os.py _execvpe()'s PATH search when */ |
| /* given the executable_list generated by Lib/subprocess.py. */ |
| saved_errno = 0; |
| for (i = 0; exec_array[i] != NULL; ++i) { |
| const char *executable = exec_array[i]; |
| if (envp) { |
| execve(executable, argv, envp); |
| } else { |
| execv(executable, argv); |
| } |
| if (errno != ENOENT && errno != ENOTDIR && saved_errno == 0) { |
| saved_errno = errno; |
| } |
| } |
| /* Report the first exec error, not the last. */ |
| if (saved_errno) |
| errno = saved_errno; |
| |
| error: |
| saved_errno = errno; |
| /* Report the posix error to our parent process. */ |
| /* We ignore all write() return values as the total size of our writes is |
| less than PIPEBUF and we cannot do anything about an error anyways. |
| Use _Py_write_noraise() to retry write() if it is interrupted by a |
| signal (fails with EINTR). */ |
| if (saved_errno) { |
| char *cur; |
| _Py_write_noraise(errpipe_write, "OSError:", 8); |
| cur = hex_errno + sizeof(hex_errno); |
| while (saved_errno != 0 && cur != hex_errno) { |
| *--cur = Py_hexdigits[saved_errno % 16]; |
| saved_errno /= 16; |
| } |
| _Py_write_noraise(errpipe_write, cur, hex_errno + sizeof(hex_errno) - cur); |
| _Py_write_noraise(errpipe_write, ":", 1); |
| if (!reached_preexec) { |
| /* Indicate to the parent that the error happened before exec(). */ |
| _Py_write_noraise(errpipe_write, "noexec", 6); |
| } |
| /* We can't call strerror(saved_errno). It is not async signal safe. |
| * The parent process will look the error message up. */ |
| } else { |
| _Py_write_noraise(errpipe_write, "SubprocessError:0:", 18); |
| _Py_write_noraise(errpipe_write, err_msg, strlen(err_msg)); |
| } |
| } |
| |
| |
| /* The main purpose of this wrapper function is to isolate vfork() from both |
| * subprocess_fork_exec() and child_exec(). A child process created via |
| * vfork() executes on the same stack as the parent process while the latter is |
| * suspended, so this function should not be inlined to avoid compiler bugs |
| * that might clobber data needed by the parent later. Additionally, |
| * child_exec() should not be inlined to avoid spurious -Wclobber warnings from |
| * GCC (see bpo-35823). |
| */ |
| _Py_NO_INLINE static pid_t |
| do_fork_exec(char *const exec_array[], |
| char *const argv[], |
| char *const envp[], |
| const char *cwd, |
| int p2cread, int p2cwrite, |
| int c2pread, int c2pwrite, |
| int errread, int errwrite, |
| int errpipe_read, int errpipe_write, |
| int close_fds, int restore_signals, |
| int call_setsid, |
| int call_setgid, gid_t gid, |
| int call_setgroups, size_t groups_size, const gid_t *groups, |
| int call_setuid, uid_t uid, int child_umask, |
| const void *child_sigmask, |
| PyObject *py_fds_to_keep, |
| PyObject *preexec_fn, |
| PyObject *preexec_fn_args_tuple) |
| { |
| |
| pid_t pid; |
| |
| #ifdef VFORK_USABLE |
| if (child_sigmask) { |
| /* These are checked by our caller; verify them in debug builds. */ |
| assert(!call_setuid); |
| assert(!call_setgid); |
| assert(!call_setgroups); |
| assert(preexec_fn == Py_None); |
| |
| pid = vfork(); |
| } else |
| #endif |
| { |
| pid = fork(); |
| } |
| |
| if (pid != 0) { |
| return pid; |
| } |
| |
| /* Child process. |
| * See the comment above child_exec() for restrictions imposed on |
| * the code below. |
| */ |
| |
| if (preexec_fn != Py_None) { |
| /* We'll be calling back into Python later so we need to do this. |
| * This call may not be async-signal-safe but neither is calling |
| * back into Python. The user asked us to use hope as a strategy |
| * to avoid deadlock... */ |
| PyOS_AfterFork_Child(); |
| } |
| |
| child_exec(exec_array, argv, envp, cwd, |
| p2cread, p2cwrite, c2pread, c2pwrite, |
| errread, errwrite, errpipe_read, errpipe_write, |
| close_fds, restore_signals, call_setsid, |
| call_setgid, gid, call_setgroups, groups_size, groups, |
| call_setuid, uid, child_umask, child_sigmask, |
| py_fds_to_keep, preexec_fn, preexec_fn_args_tuple); |
| _exit(255); |
| return 0; /* Dead code to avoid a potential compiler warning. */ |
| } |
| |
| |
| static PyObject * |
| subprocess_fork_exec(PyObject *module, PyObject *args) |
| { |
| PyObject *gc_module = NULL; |
| PyObject *executable_list, *py_fds_to_keep; |
| PyObject *env_list, *preexec_fn; |
| PyObject *process_args, *converted_args = NULL, *fast_args = NULL; |
| PyObject *preexec_fn_args_tuple = NULL; |
| PyObject *groups_list; |
| PyObject *uid_object, *gid_object; |
| int p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite; |
| int errpipe_read, errpipe_write, close_fds, restore_signals; |
| int call_setsid; |
| int call_setgid = 0, call_setgroups = 0, call_setuid = 0; |
| uid_t uid; |
| gid_t gid, *groups = NULL; |
| int child_umask; |
| PyObject *cwd_obj, *cwd_obj2 = NULL; |
| const char *cwd; |
| pid_t pid = -1; |
| int need_to_reenable_gc = 0; |
| char *const *exec_array, *const *argv = NULL, *const *envp = NULL; |
| Py_ssize_t arg_num, num_groups = 0; |
| int need_after_fork = 0; |
| int saved_errno = 0; |
| _posixsubprocessstate *state = get_posixsubprocess_state(module); |
| |
| if (!PyArg_ParseTuple( |
| args, "OOpO!OOiiiiiiiiiiOOOiO:fork_exec", |
| &process_args, &executable_list, |
| &close_fds, &PyTuple_Type, &py_fds_to_keep, |
| &cwd_obj, &env_list, |
| &p2cread, &p2cwrite, &c2pread, &c2pwrite, |
| &errread, &errwrite, &errpipe_read, &errpipe_write, |
| &restore_signals, &call_setsid, |
| &gid_object, &groups_list, &uid_object, &child_umask, |
| &preexec_fn)) |
| return NULL; |
| |
| if ((preexec_fn != Py_None) && |
| (PyInterpreterState_Get() != PyInterpreterState_Main())) { |
| PyErr_SetString(PyExc_RuntimeError, |
| "preexec_fn not supported within subinterpreters"); |
| return NULL; |
| } |
| |
| if (close_fds && errpipe_write < 3) { /* precondition */ |
| PyErr_SetString(PyExc_ValueError, "errpipe_write must be >= 3"); |
| return NULL; |
| } |
| if (_sanity_check_python_fd_sequence(py_fds_to_keep)) { |
| PyErr_SetString(PyExc_ValueError, "bad value(s) in fds_to_keep"); |
| return NULL; |
| } |
| |
| PyInterpreterState *interp = PyInterpreterState_Get(); |
| const PyConfig *config = _PyInterpreterState_GetConfig(interp); |
| if (config->_isolated_interpreter) { |
| PyErr_SetString(PyExc_RuntimeError, |
| "subprocess not supported for isolated subinterpreters"); |
| return NULL; |
| } |
| |
| /* We need to call gc.disable() when we'll be calling preexec_fn */ |
| if (preexec_fn != Py_None) { |
| PyObject *result; |
| |
| gc_module = PyImport_ImportModule("gc"); |
| if (gc_module == NULL) |
| return NULL; |
| result = PyObject_CallMethodNoArgs( |
| gc_module, state->isenabled); |
| if (result == NULL) { |
| Py_DECREF(gc_module); |
| return NULL; |
| } |
| need_to_reenable_gc = PyObject_IsTrue(result); |
| Py_DECREF(result); |
| if (need_to_reenable_gc == -1) { |
| Py_DECREF(gc_module); |
| return NULL; |
| } |
| result = PyObject_CallMethodNoArgs( |
| gc_module, state->disable); |
| if (result == NULL) { |
| Py_DECREF(gc_module); |
| return NULL; |
| } |
| Py_DECREF(result); |
| } |
| |
| exec_array = _PySequence_BytesToCharpArray(executable_list); |
| if (!exec_array) |
| goto cleanup; |
| |
| /* Convert args and env into appropriate arguments for exec() */ |
| /* These conversions are done in the parent process to avoid allocating |
| or freeing memory in the child process. */ |
| if (process_args != Py_None) { |
| Py_ssize_t num_args; |
| /* Equivalent to: */ |
| /* tuple(PyUnicode_FSConverter(arg) for arg in process_args) */ |
| fast_args = PySequence_Fast(process_args, "argv must be a tuple"); |
| if (fast_args == NULL) |
| goto cleanup; |
| num_args = PySequence_Fast_GET_SIZE(fast_args); |
| converted_args = PyTuple_New(num_args); |
| if (converted_args == NULL) |
| goto cleanup; |
| for (arg_num = 0; arg_num < num_args; ++arg_num) { |
| PyObject *borrowed_arg, *converted_arg; |
| if (PySequence_Fast_GET_SIZE(fast_args) != num_args) { |
| PyErr_SetString(PyExc_RuntimeError, "args changed during iteration"); |
| goto cleanup; |
| } |
| borrowed_arg = PySequence_Fast_GET_ITEM(fast_args, arg_num); |
| if (PyUnicode_FSConverter(borrowed_arg, &converted_arg) == 0) |
| goto cleanup; |
| PyTuple_SET_ITEM(converted_args, arg_num, converted_arg); |
| } |
| |
| argv = _PySequence_BytesToCharpArray(converted_args); |
| Py_CLEAR(converted_args); |
| Py_CLEAR(fast_args); |
| if (!argv) |
| goto cleanup; |
| } |
| |
| if (env_list != Py_None) { |
| envp = _PySequence_BytesToCharpArray(env_list); |
| if (!envp) |
| goto cleanup; |
| } |
| |
| if (cwd_obj != Py_None) { |
| if (PyUnicode_FSConverter(cwd_obj, &cwd_obj2) == 0) |
| goto cleanup; |
| cwd = PyBytes_AsString(cwd_obj2); |
| } else { |
| cwd = NULL; |
| } |
| |
| if (groups_list != Py_None) { |
| #ifdef HAVE_SETGROUPS |
| Py_ssize_t i; |
| unsigned long gid; |
| |
| if (!PyList_Check(groups_list)) { |
| PyErr_SetString(PyExc_TypeError, |
| "setgroups argument must be a list"); |
| goto cleanup; |
| } |
| num_groups = PySequence_Size(groups_list); |
| |
| if (num_groups < 0) |
| goto cleanup; |
| |
| if (num_groups > MAX_GROUPS) { |
| PyErr_SetString(PyExc_ValueError, "too many groups"); |
| goto cleanup; |
| } |
| |
| if ((groups = PyMem_RawMalloc(num_groups * sizeof(gid_t))) == NULL) { |
| PyErr_SetString(PyExc_MemoryError, |
| "failed to allocate memory for group list"); |
| goto cleanup; |
| } |
| |
| for (i = 0; i < num_groups; i++) { |
| PyObject *elem; |
| elem = PySequence_GetItem(groups_list, i); |
| if (!elem) |
| goto cleanup; |
| if (!PyLong_Check(elem)) { |
| PyErr_SetString(PyExc_TypeError, |
| "groups must be integers"); |
| Py_DECREF(elem); |
| goto cleanup; |
| } else { |
| /* In posixmodule.c UnsignedLong is used as a fallback value |
| * if the value provided does not fit in a Long. Since we are |
| * already doing the bounds checking on the Python side, we |
| * can go directly to an UnsignedLong here. */ |
| if (!_Py_Gid_Converter(elem, &gid)) { |
| Py_DECREF(elem); |
| PyErr_SetString(PyExc_ValueError, "invalid group id"); |
| goto cleanup; |
| } |
| groups[i] = gid; |
| } |
| Py_DECREF(elem); |
| } |
| call_setgroups = 1; |
| |
| #else /* HAVE_SETGROUPS */ |
| PyErr_BadInternalCall(); |
| goto cleanup; |
| #endif /* HAVE_SETGROUPS */ |
| } |
| |
| if (gid_object != Py_None) { |
| #ifdef HAVE_SETREGID |
| if (!_Py_Gid_Converter(gid_object, &gid)) |
| goto cleanup; |
| |
| call_setgid = 1; |
| |
| #else /* HAVE_SETREGID */ |
| PyErr_BadInternalCall(); |
| goto cleanup; |
| #endif /* HAVE_SETREUID */ |
| } |
| |
| if (uid_object != Py_None) { |
| #ifdef HAVE_SETREUID |
| if (!_Py_Uid_Converter(uid_object, &uid)) |
| goto cleanup; |
| |
| call_setuid = 1; |
| |
| #else /* HAVE_SETREUID */ |
| PyErr_BadInternalCall(); |
| goto cleanup; |
| #endif /* HAVE_SETREUID */ |
| } |
| |
| /* This must be the last thing done before fork() because we do not |
| * want to call PyOS_BeforeFork() if there is any chance of another |
| * error leading to the cleanup: code without calling fork(). */ |
| if (preexec_fn != Py_None) { |
| preexec_fn_args_tuple = PyTuple_New(0); |
| if (!preexec_fn_args_tuple) |
| goto cleanup; |
| PyOS_BeforeFork(); |
| need_after_fork = 1; |
| } |
| |
| /* NOTE: When old_sigmask is non-NULL, do_fork_exec() may use vfork(). */ |
| const void *old_sigmask = NULL; |
| #ifdef VFORK_USABLE |
| /* Use vfork() only if it's safe. See the comment above child_exec(). */ |
| sigset_t old_sigs; |
| if (preexec_fn == Py_None && |
| !call_setuid && !call_setgid && !call_setgroups) { |
| /* Block all signals to ensure that no signal handlers are run in the |
| * child process while it shares memory with us. Note that signals |
| * used internally by C libraries won't be blocked by |
| * pthread_sigmask(), but signal handlers installed by C libraries |
| * normally service only signals originating from *within the process*, |
| * so it should be sufficient to consider any library function that |
| * might send such a signal to be vfork-unsafe and do not call it in |
| * the child. |
| */ |
| sigset_t all_sigs; |
| sigfillset(&all_sigs); |
| if ((saved_errno = pthread_sigmask(SIG_BLOCK, &all_sigs, &old_sigs))) { |
| goto cleanup; |
| } |
| old_sigmask = &old_sigs; |
| } |
| #endif |
| |
| pid = do_fork_exec(exec_array, argv, envp, cwd, |
| p2cread, p2cwrite, c2pread, c2pwrite, |
| errread, errwrite, errpipe_read, errpipe_write, |
| close_fds, restore_signals, call_setsid, |
| call_setgid, gid, call_setgroups, num_groups, groups, |
| call_setuid, uid, child_umask, old_sigmask, |
| py_fds_to_keep, preexec_fn, preexec_fn_args_tuple); |
| |
| /* Parent (original) process */ |
| if (pid == -1) { |
| /* Capture errno for the exception. */ |
| saved_errno = errno; |
| } |
| |
| #ifdef VFORK_USABLE |
| if (old_sigmask) { |
| /* vfork() semantics guarantees that the parent is blocked |
| * until the child performs _exit() or execve(), so it is safe |
| * to unblock signals once we're here. |
| * Note that in environments where vfork() is implemented as fork(), |
| * such as QEMU user-mode emulation, the parent won't be blocked, |
| * but it won't share the address space with the child, |
| * so it's still safe to unblock the signals. |
| * |
| * We don't handle errors here because this call can't fail |
| * if valid arguments are given, and because there is no good |
| * way for the caller to deal with a failure to restore |
| * the thread signal mask. */ |
| (void) pthread_sigmask(SIG_SETMASK, old_sigmask, NULL); |
| } |
| #endif |
| |
| if (need_after_fork) |
| PyOS_AfterFork_Parent(); |
| |
| cleanup: |
| if (saved_errno != 0) { |
| errno = saved_errno; |
| /* We can't call this above as PyOS_AfterFork_Parent() calls back |
| * into Python code which would see the unreturned error. */ |
| PyErr_SetFromErrno(PyExc_OSError); |
| } |
| |
| Py_XDECREF(preexec_fn_args_tuple); |
| PyMem_RawFree(groups); |
| Py_XDECREF(cwd_obj2); |
| if (envp) |
| _Py_FreeCharPArray(envp); |
| Py_XDECREF(converted_args); |
| Py_XDECREF(fast_args); |
| if (argv) |
| _Py_FreeCharPArray(argv); |
| if (exec_array) |
| _Py_FreeCharPArray(exec_array); |
| |
| _enable_gc(need_to_reenable_gc, gc_module, state); |
| Py_XDECREF(gc_module); |
| |
| return pid == -1 ? NULL : PyLong_FromPid(pid); |
| } |
| |
| |
| PyDoc_STRVAR(subprocess_fork_exec_doc, |
| "fork_exec(args, executable_list, close_fds, pass_fds, cwd, env,\n\ |
| p2cread, p2cwrite, c2pread, c2pwrite,\n\ |
| errread, errwrite, errpipe_read, errpipe_write,\n\ |
| restore_signals, call_setsid,\n\ |
| gid, groups_list, uid,\n\ |
| preexec_fn)\n\ |
| \n\ |
| Forks a child process, closes parent file descriptors as appropriate in the\n\ |
| child and dups the few that are needed before calling exec() in the child\n\ |
| process.\n\ |
| \n\ |
| If close_fds is true, close file descriptors 3 and higher, except those listed\n\ |
| in the sorted tuple pass_fds.\n\ |
| \n\ |
| The preexec_fn, if supplied, will be called immediately before closing file\n\ |
| descriptors and exec.\n\ |
| WARNING: preexec_fn is NOT SAFE if your application uses threads.\n\ |
| It may trigger infrequent, difficult to debug deadlocks.\n\ |
| \n\ |
| If an error occurs in the child process before the exec, it is\n\ |
| serialized and written to the errpipe_write fd per subprocess.py.\n\ |
| \n\ |
| Returns: the child process's PID.\n\ |
| \n\ |
| Raises: Only on an error in the parent process.\n\ |
| "); |
| |
| /* module level code ********************************************************/ |
| |
| PyDoc_STRVAR(module_doc, |
| "A POSIX helper for the subprocess module."); |
| |
| static int |
| _posixsubprocess_exec(PyObject *module) |
| { |
| _posixsubprocessstate *state = get_posixsubprocess_state(module); |
| |
| state->disable = PyUnicode_InternFromString("disable"); |
| if (state->disable == NULL) { |
| return -1; |
| } |
| |
| state->enable = PyUnicode_InternFromString("enable"); |
| if (state->enable == NULL) { |
| return -1; |
| } |
| |
| state->isenabled = PyUnicode_InternFromString("isenabled"); |
| if (state->isenabled == NULL) { |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| static PyMethodDef module_methods[] = { |
| {"fork_exec", subprocess_fork_exec, METH_VARARGS, subprocess_fork_exec_doc}, |
| {NULL, NULL} /* sentinel */ |
| }; |
| |
| static PyModuleDef_Slot _posixsubprocess_slots[] = { |
| {Py_mod_exec, _posixsubprocess_exec}, |
| {0, NULL} |
| }; |
| |
| static int _posixsubprocess_traverse(PyObject *m, visitproc visit, void *arg) { |
| Py_VISIT(get_posixsubprocess_state(m)->disable); |
| Py_VISIT(get_posixsubprocess_state(m)->enable); |
| Py_VISIT(get_posixsubprocess_state(m)->isenabled); |
| return 0; |
| } |
| |
| static int _posixsubprocess_clear(PyObject *m) { |
| Py_CLEAR(get_posixsubprocess_state(m)->disable); |
| Py_CLEAR(get_posixsubprocess_state(m)->enable); |
| Py_CLEAR(get_posixsubprocess_state(m)->isenabled); |
| return 0; |
| } |
| |
| static void _posixsubprocess_free(void *m) { |
| _posixsubprocess_clear((PyObject *)m); |
| } |
| |
| static struct PyModuleDef _posixsubprocessmodule = { |
| PyModuleDef_HEAD_INIT, |
| .m_name = "_posixsubprocess", |
| .m_doc = module_doc, |
| .m_size = sizeof(_posixsubprocessstate), |
| .m_methods = module_methods, |
| .m_slots = _posixsubprocess_slots, |
| .m_traverse = _posixsubprocess_traverse, |
| .m_clear = _posixsubprocess_clear, |
| .m_free = _posixsubprocess_free, |
| }; |
| |
| PyMODINIT_FUNC |
| PyInit__posixsubprocess(void) |
| { |
| return PyModuleDef_Init(&_posixsubprocessmodule); |
| } |