diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/spawni.c')
| -rw-r--r-- | sysdeps/unix/sysv/linux/spawni.c | 397 |
1 files changed, 0 insertions, 397 deletions
diff --git a/sysdeps/unix/sysv/linux/spawni.c b/sysdeps/unix/sysv/linux/spawni.c deleted file mode 100644 index c56f894a82..0000000000 --- a/sysdeps/unix/sysv/linux/spawni.c +++ /dev/null @@ -1,397 +0,0 @@ -/* POSIX spawn interface. Linux version. - Copyright (C) 2016-2017 Free Software Foundation, Inc. - This file is part of the GNU C Library. - - The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public - License as published by the Free Software Foundation; either - version 2.1 of the License, or (at your option) any later version. - - The GNU C Library is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public - License along with the GNU C Library; if not, see - <http://www.gnu.org/licenses/>. */ - -#include <spawn.h> -#include <assert.h> -#include <fcntl.h> -#include <paths.h> -#include <string.h> -#include <sys/resource.h> -#include <sys/wait.h> -#include <sys/param.h> -#include <sys/mman.h> -#include <not-cancel.h> -#include <local-setxid.h> -#include <shlib-compat.h> -#include <nptl/pthreadP.h> -#include <dl-sysdep.h> -#include <libc-pointer-arith.h> -#include <ldsodefs.h> -#include "spawn_int.h" - -/* The Linux implementation of posix_spawn{p} uses the clone syscall directly - with CLONE_VM and CLONE_VFORK flags and an allocated stack. The new stack - and start function solves most the vfork limitation (possible parent - clobber due stack spilling). The remaining issue are: - - 1. That no signal handlers must run in child context, to avoid corrupting - parent's state. - 2. The parent must ensure child's stack freeing. - 3. Child must synchronize with parent to enforce 2. and to possible - return execv issues. - - The first issue is solved by blocking all signals in child, even - the NPTL-internal ones (SIGCANCEL and SIGSETXID). The second and - third issue is done by a stack allocation in parent, and by using a - field in struct spawn_args where the child can write an error - code. CLONE_VFORK ensures that the parent does not run until the - child has either exec'ed successfully or exited. */ - - -/* The Unix standard contains a long explanation of the way to signal - an error after the fork() was successful. Since no new wait status - was wanted there is no way to signal an error using one of the - available methods. The committee chose to signal an error by a - normal program exit with the exit code 127. */ -#define SPAWN_ERROR 127 - -#ifdef __ia64__ -# define CLONE(__fn, __stackbase, __stacksize, __flags, __args) \ - __clone2 (__fn, __stackbase, __stacksize, __flags, __args, 0, 0, 0) -#else -# define CLONE(__fn, __stack, __stacksize, __flags, __args) \ - __clone (__fn, __stack, __flags, __args) -#endif - -/* Since ia64 wants the stackbase w/clone2, re-use the grows-up macro. */ -#if _STACK_GROWS_UP || defined (__ia64__) -# define STACK(__stack, __stack_size) (__stack) -#elif _STACK_GROWS_DOWN -# define STACK(__stack, __stack_size) (__stack + __stack_size) -#endif - - -struct posix_spawn_args -{ - sigset_t oldmask; - const char *file; - int (*exec) (const char *, char *const *, char *const *); - const posix_spawn_file_actions_t *fa; - const posix_spawnattr_t *restrict attr; - char *const *argv; - ptrdiff_t argc; - char *const *envp; - int xflags; - int err; -}; - -/* Older version requires that shell script without shebang definition - to be called explicitly using /bin/sh (_PATH_BSHELL). */ -static void -maybe_script_execute (struct posix_spawn_args *args) -{ - if (SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_15) - && (args->xflags & SPAWN_XFLAGS_TRY_SHELL) && errno == ENOEXEC) - { - char *const *argv = args->argv; - ptrdiff_t argc = args->argc; - - /* Construct an argument list for the shell. */ - char *new_argv[argc + 1]; - new_argv[0] = (char *) _PATH_BSHELL; - new_argv[1] = (char *) args->file; - if (argc > 1) - memcpy (new_argv + 2, argv + 1, argc * sizeof(char *)); - else - new_argv[2] = NULL; - - /* Execute the shell. */ - args->exec (new_argv[0], new_argv, args->envp); - } -} - -/* Function used in the clone call to setup the signals mask, posix_spawn - attributes, and file actions. It run on its own stack (provided by the - posix_spawn call). */ -static int -__spawni_child (void *arguments) -{ - struct posix_spawn_args *args = arguments; - const posix_spawnattr_t *restrict attr = args->attr; - const posix_spawn_file_actions_t *file_actions = args->fa; - - /* The child must ensure that no signal handler are enabled because it shared - memory with parent, so the signal disposition must be either SIG_DFL or - SIG_IGN. It does by iterating over all signals and although it could - possibly be more optimized (by tracking which signal potentially have a - signal handler), it might requires system specific solutions (since the - sigset_t data type can be very different on different architectures). */ - struct sigaction sa; - memset (&sa, '\0', sizeof (sa)); - - sigset_t hset; - __sigprocmask (SIG_BLOCK, 0, &hset); - for (int sig = 1; sig < _NSIG; ++sig) - { - if ((attr->__flags & POSIX_SPAWN_SETSIGDEF) - && sigismember (&attr->__sd, sig)) - { - sa.sa_handler = SIG_DFL; - } - else if (sigismember (&hset, sig)) - { - if (__nptl_is_internal_signal (sig)) - sa.sa_handler = SIG_IGN; - else - { - __libc_sigaction (sig, 0, &sa); - if (sa.sa_handler == SIG_IGN) - continue; - sa.sa_handler = SIG_DFL; - } - } - else - continue; - - __libc_sigaction (sig, &sa, 0); - } - -#ifdef _POSIX_PRIORITY_SCHEDULING - /* Set the scheduling algorithm and parameters. */ - if ((attr->__flags & (POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER)) - == POSIX_SPAWN_SETSCHEDPARAM) - { - if (__sched_setparam (0, &attr->__sp) == -1) - goto fail; - } - else if ((attr->__flags & POSIX_SPAWN_SETSCHEDULER) != 0) - { - if (__sched_setscheduler (0, attr->__policy, &attr->__sp) == -1) - goto fail; - } -#endif - - if ((attr->__flags & POSIX_SPAWN_SETSID) != 0 - && __setsid () < 0) - goto fail; - - /* Set the process group ID. */ - if ((attr->__flags & POSIX_SPAWN_SETPGROUP) != 0 - && __setpgid (0, attr->__pgrp) != 0) - goto fail; - - /* Set the effective user and group IDs. */ - if ((attr->__flags & POSIX_SPAWN_RESETIDS) != 0 - && (local_seteuid (__getuid ()) != 0 - || local_setegid (__getgid ()) != 0)) - goto fail; - - /* Execute the file actions. */ - if (file_actions != 0) - { - int cnt; - struct rlimit64 fdlimit; - bool have_fdlimit = false; - - for (cnt = 0; cnt < file_actions->__used; ++cnt) - { - struct __spawn_action *action = &file_actions->__actions[cnt]; - - switch (action->tag) - { - case spawn_do_close: - if (close_not_cancel (action->action.close_action.fd) != 0) - { - if (!have_fdlimit) - { - __getrlimit64 (RLIMIT_NOFILE, &fdlimit); - have_fdlimit = true; - } - - /* Signal errors only for file descriptors out of range. */ - if (action->action.close_action.fd < 0 - || action->action.close_action.fd >= fdlimit.rlim_cur) - goto fail; - } - break; - - case spawn_do_open: - { - /* POSIX states that if fildes was already an open file descriptor, - it shall be closed before the new file is opened. This avoid - pontential issues when posix_spawn plus addopen action is called - with the process already at maximum number of file descriptor - opened and also for multiple actions on single-open special - paths (like /dev/watchdog). */ - close_not_cancel (action->action.open_action.fd); - - int ret = open_not_cancel (action->action.open_action.path, - action->action. - open_action.oflag | O_LARGEFILE, - action->action.open_action.mode); - - if (ret == -1) - goto fail; - - int new_fd = ret; - - /* Make sure the desired file descriptor is used. */ - if (ret != action->action.open_action.fd) - { - if (__dup2 (new_fd, action->action.open_action.fd) - != action->action.open_action.fd) - goto fail; - - if (close_not_cancel (new_fd) != 0) - goto fail; - } - } - break; - - case spawn_do_dup2: - if (__dup2 (action->action.dup2_action.fd, - action->action.dup2_action.newfd) - != action->action.dup2_action.newfd) - goto fail; - break; - } - } - } - - /* Set the initial signal mask of the child if POSIX_SPAWN_SETSIGMASK - is set, otherwise restore the previous one. */ - __sigprocmask (SIG_SETMASK, (attr->__flags & POSIX_SPAWN_SETSIGMASK) - ? &attr->__ss : &args->oldmask, 0); - - args->err = 0; - args->exec (args->file, args->argv, args->envp); - - /* This is compatibility function required to enable posix_spawn run - script without shebang definition for older posix_spawn versions - (2.15). */ - maybe_script_execute (args); - -fail: - /* errno should have an appropriate non-zero value; otherwise, - there's a bug in glibc or the kernel. For lack of an error code - (EINTERNALBUG) describing that, use ECHILD. Another option would - be to set args->err to some negative sentinel and have the parent - abort(), but that seems needlessly harsh. */ - args->err = errno ? : ECHILD; - _exit (SPAWN_ERROR); -} - -/* Spawn a new process executing PATH with the attributes describes in *ATTRP. - Before running the process perform the actions described in FILE-ACTIONS. */ -static int -__spawnix (pid_t * pid, const char *file, - const posix_spawn_file_actions_t * file_actions, - const posix_spawnattr_t * attrp, char *const argv[], - char *const envp[], int xflags, - int (*exec) (const char *, char *const *, char *const *)) -{ - pid_t new_pid; - struct posix_spawn_args args; - int ec; - - /* To avoid imposing hard limits on posix_spawn{p} the total number of - arguments is first calculated to allocate a mmap to hold all possible - values. */ - ptrdiff_t argc = 0; - /* Linux allows at most max (0x7FFFFFFF, 1/4 stack size) arguments - to be used in a execve call. We limit to INT_MAX minus one due the - compatiblity code that may execute a shell script (maybe_script_execute) - where it will construct another argument list with an additional - argument. */ - ptrdiff_t limit = INT_MAX - 1; - while (argv[argc++] != NULL) - if (argc == limit) - { - errno = E2BIG; - return errno; - } - - int prot = (PROT_READ | PROT_WRITE - | ((GL (dl_stack_flags) & PF_X) ? PROT_EXEC : 0)); - - /* Add a slack area for child's stack. */ - size_t argv_size = (argc * sizeof (void *)) + 512; - /* We need at least a few pages in case the compiler's stack checking is - enabled. In some configs, it is known to use at least 24KiB. We use - 32KiB to be "safe" from anything the compiler might do. Besides, the - extra pages won't actually be allocated unless they get used. */ - argv_size += (32 * 1024); - size_t stack_size = ALIGN_UP (argv_size, GLRO(dl_pagesize)); - void *stack = __mmap (NULL, stack_size, prot, - MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0); - if (__glibc_unlikely (stack == MAP_FAILED)) - return errno; - - /* Disable asynchronous cancellation. */ - int state; - __libc_ptf_call (__pthread_setcancelstate, - (PTHREAD_CANCEL_DISABLE, &state), 0); - - /* Child must set args.err to something non-negative - we rely on - the parent and child sharing VM. */ - args.err = -1; - args.file = file; - args.exec = exec; - args.fa = file_actions; - args.attr = attrp ? attrp : &(const posix_spawnattr_t) { 0 }; - args.argv = argv; - args.argc = argc; - args.envp = envp; - args.xflags = xflags; - - __libc_signal_block_all (&args.oldmask); - - /* The clone flags used will create a new child that will run in the same - memory space (CLONE_VM) and the execution of calling thread will be - suspend until the child calls execve or _exit. - - Also since the calling thread execution will be suspend, there is not - need for CLONE_SETTLS. Although parent and child share the same TLS - namespace, there will be no concurrent access for TLS variables (errno - for instance). */ - new_pid = CLONE (__spawni_child, STACK (stack, stack_size), stack_size, - CLONE_VM | CLONE_VFORK | SIGCHLD, &args); - - if (new_pid > 0) - { - ec = args.err; - assert (ec >= 0); - if (ec != 0) - __waitpid (new_pid, NULL, 0); - } - else - ec = -new_pid; - - __munmap (stack, stack_size); - - if ((ec == 0) && (pid != NULL)) - *pid = new_pid; - - __libc_signal_restore_set (&args.oldmask); - - __libc_ptf_call (__pthread_setcancelstate, (state, NULL), 0); - - return ec; -} - -/* Spawn a new process executing PATH with the attributes describes in *ATTRP. - Before running the process perform the actions described in FILE-ACTIONS. */ -int -__spawni (pid_t * pid, const char *file, - const posix_spawn_file_actions_t * acts, - const posix_spawnattr_t * attrp, char *const argv[], - char *const envp[], int xflags) -{ - return __spawnix (pid, file, acts, attrp, argv, envp, xflags, - xflags & SPAWN_XFLAGS_USE_PATH ? __execvpe : __execve); -} |