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986ad61e | 1 | /* Guts of POSIX spawn interface. Generic POSIX.1 version. |
04277e02 | 2 | Copyright (C) 2000-2019 Free Software Foundation, Inc. |
a5a6f926 UD |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
41bdb6e2 AJ |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
a5a6f926 UD |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
a5a6f926 | 14 | |
41bdb6e2 | 15 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
a5a6f926 | 18 | |
ccfb2964 AZ |
19 | #include <spawn.h> |
20 | #include <assert.h> | |
a5a6f926 UD |
21 | #include <fcntl.h> |
22 | #include <paths.h> | |
a5a6f926 | 23 | #include <string.h> |
cfa28e56 | 24 | #include <sys/resource.h> |
ccfb2964 AZ |
25 | #include <sys/wait.h> |
26 | #include <sys/param.h> | |
27 | #include <sys/mman.h> | |
73299943 | 28 | #include <not-cancel.h> |
1b8373f4 | 29 | #include <local-setxid.h> |
d96de963 | 30 | #include <shlib-compat.h> |
ccfb2964 AZ |
31 | #include <nptl/pthreadP.h> |
32 | #include <dl-sysdep.h> | |
33 | #include <libc-pointer-arith.h> | |
34 | #include <ldsodefs.h> | |
35 | #include "spawn_int.h" | |
a5a6f926 UD |
36 | |
37 | ||
38 | /* The Unix standard contains a long explanation of the way to signal | |
39 | an error after the fork() was successful. Since no new wait status | |
40 | was wanted there is no way to signal an error using one of the | |
41 | available methods. The committee chose to signal an error by a | |
42 | normal program exit with the exit code 127. */ | |
43 | #define SPAWN_ERROR 127 | |
44 | ||
ccfb2964 | 45 | struct posix_spawn_args |
a5a6f926 | 46 | { |
ccfb2964 AZ |
47 | sigset_t oldmask; |
48 | const char *file; | |
49 | int (*exec) (const char *, char *const *, char *const *); | |
50 | const posix_spawn_file_actions_t *fa; | |
51 | const posix_spawnattr_t *restrict attr; | |
52 | char *const *argv; | |
53 | ptrdiff_t argc; | |
54 | char *const *envp; | |
55 | int xflags; | |
56 | int pipe[2]; | |
57 | }; | |
58 | ||
59 | /* Older version requires that shell script without shebang definition | |
60 | to be called explicitly using /bin/sh (_PATH_BSHELL). */ | |
61 | static void | |
62 | maybe_script_execute (struct posix_spawn_args *args) | |
ecb1482f RM |
63 | { |
64 | if (SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_15) | |
ccfb2964 | 65 | && (args->xflags & SPAWN_XFLAGS_TRY_SHELL) && errno == ENOEXEC) |
a5a6f926 | 66 | { |
ccfb2964 AZ |
67 | char *const *argv = args->argv; |
68 | ptrdiff_t argc = args->argc; | |
69 | ||
70 | /* Construct an argument list for the shell. */ | |
f5ec0ea9 | 71 | char *new_argv[argc + 2]; |
ccfb2964 AZ |
72 | new_argv[0] = (char *) _PATH_BSHELL; |
73 | new_argv[1] = (char *) args->file; | |
74 | if (argc > 1) | |
75 | memcpy (new_argv + 2, argv + 1, argc * sizeof(char *)); | |
76 | else | |
77 | new_argv[2] = NULL; | |
a5a6f926 | 78 | |
ccfb2964 AZ |
79 | /* Execute the shell. */ |
80 | args->exec (new_argv[0], new_argv, args->envp); | |
a5a6f926 | 81 | } |
ccfb2964 AZ |
82 | } |
83 | ||
84 | /* Function used in the clone call to setup the signals mask, posix_spawn | |
85 | attributes, and file actions. */ | |
86 | static int | |
87 | __spawni_child (void *arguments) | |
88 | { | |
89 | struct posix_spawn_args *args = arguments; | |
90 | const posix_spawnattr_t *restrict attr = args->attr; | |
91 | const posix_spawn_file_actions_t *file_actions = args->fa; | |
92 | int ret; | |
a5a6f926 | 93 | |
ccfb2964 | 94 | __close (args->pipe[0]); |
a5a6f926 UD |
95 | |
96 | /* Set signal default action. */ | |
ccfb2964 | 97 | if ((attr->__flags & POSIX_SPAWN_SETSIGDEF) != 0) |
a5a6f926 UD |
98 | { |
99 | /* We have to iterate over all signals. This could possibly be | |
100 | done better but it requires system specific solutions since | |
101 | the sigset_t data type can be very different on different | |
102 | architectures. */ | |
103 | int sig; | |
104 | struct sigaction sa; | |
105 | ||
106 | memset (&sa, '\0', sizeof (sa)); | |
107 | sa.sa_handler = SIG_DFL; | |
108 | ||
ba3752d5 | 109 | for (sig = 1; sig <= _NSIG; ++sig) |
ccfb2964 | 110 | if (__sigismember (&attr->__sd, sig) != 0 |
a5a6f926 | 111 | && __sigaction (sig, &sa, NULL) != 0) |
ccfb2964 | 112 | goto fail; |
a5a6f926 UD |
113 | } |
114 | ||
115 | #ifdef _POSIX_PRIORITY_SCHEDULING | |
116 | /* Set the scheduling algorithm and parameters. */ | |
ccfb2964 | 117 | if ((attr->__flags & (POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER)) |
a5a6f926 UD |
118 | == POSIX_SPAWN_SETSCHEDPARAM) |
119 | { | |
db6b2f25 | 120 | if (__sched_setparam (0, &attr->__sp) == -1) |
ccfb2964 | 121 | goto fail; |
a5a6f926 | 122 | } |
ccfb2964 | 123 | else if ((attr->__flags & POSIX_SPAWN_SETSCHEDULER) != 0) |
a5a6f926 | 124 | { |
db6b2f25 | 125 | if (__sched_setscheduler (0, attr->__policy, &attr->__sp) == -1) |
ccfb2964 | 126 | goto fail; |
a5a6f926 UD |
127 | } |
128 | #endif | |
129 | ||
ccfb2964 AZ |
130 | /* Set the process session ID. */ |
131 | if ((attr->__flags & POSIX_SPAWN_SETSID) != 0 | |
db6b2f25 | 132 | && __setsid () < 0) |
ccfb2964 | 133 | goto fail; |
daeb1fa2 | 134 | |
a5a6f926 | 135 | /* Set the process group ID. */ |
ccfb2964 | 136 | if ((attr->__flags & POSIX_SPAWN_SETPGROUP) != 0 |
db6b2f25 | 137 | && __setpgid (0, attr->__pgrp) != 0) |
ccfb2964 | 138 | goto fail; |
a5a6f926 UD |
139 | |
140 | /* Set the effective user and group IDs. */ | |
ccfb2964 | 141 | if ((attr->__flags & POSIX_SPAWN_RESETIDS) != 0 |
db6b2f25 AZ |
142 | && (local_seteuid (__getuid ()) != 0 |
143 | || local_setegid (__getgid ())) != 0) | |
ccfb2964 | 144 | goto fail; |
a5a6f926 UD |
145 | |
146 | /* Execute the file actions. */ | |
147 | if (file_actions != NULL) | |
148 | { | |
149 | int cnt; | |
cfa28e56 UD |
150 | struct rlimit64 fdlimit; |
151 | bool have_fdlimit = false; | |
a5a6f926 UD |
152 | |
153 | for (cnt = 0; cnt < file_actions->__used; ++cnt) | |
154 | { | |
155 | struct __spawn_action *action = &file_actions->__actions[cnt]; | |
156 | ||
157 | switch (action->tag) | |
158 | { | |
159 | case spawn_do_close: | |
c181840c | 160 | if (__close_nocancel (action->action.close_action.fd) != 0) |
cfa28e56 | 161 | { |
ccfb2964 | 162 | if (have_fdlimit == 0) |
cfa28e56 | 163 | { |
1a2325c0 | 164 | __getrlimit64 (RLIMIT_NOFILE, &fdlimit); |
cfa28e56 UD |
165 | have_fdlimit = true; |
166 | } | |
167 | ||
168 | /* Only signal errors for file descriptors out of range. */ | |
169 | if (action->action.close_action.fd < 0 | |
170 | || action->action.close_action.fd >= fdlimit.rlim_cur) | |
db6b2f25 | 171 | goto fail; |
cfa28e56 | 172 | } |
a5a6f926 UD |
173 | break; |
174 | ||
175 | case spawn_do_open: | |
176 | { | |
ccfb2964 AZ |
177 | /* POSIX states that if fildes was already an open file descriptor, |
178 | it shall be closed before the new file is opened. This avoid | |
179 | pontential issues when posix_spawn plus addopen action is called | |
180 | with the process already at maximum number of file descriptor | |
181 | opened and also for multiple actions on single-open special | |
182 | paths (like /dev/watchdog). */ | |
c181840c | 183 | __close_nocancel (action->action.open_action.fd); |
ccfb2964 | 184 | |
c2284574 | 185 | int new_fd = __open_nocancel (action->action.open_action.path, |
7231452e UD |
186 | action->action.open_action.oflag |
187 | | O_LARGEFILE, | |
188 | action->action.open_action.mode); | |
a5a6f926 | 189 | |
db6b2f25 | 190 | if (new_fd == -1) |
ccfb2964 | 191 | goto fail; |
a5a6f926 UD |
192 | |
193 | /* Make sure the desired file descriptor is used. */ | |
194 | if (new_fd != action->action.open_action.fd) | |
195 | { | |
db6b2f25 | 196 | if (__dup2 (new_fd, action->action.open_action.fd) |
08c7f6b0 | 197 | != action->action.open_action.fd) |
ccfb2964 | 198 | goto fail; |
a5a6f926 | 199 | |
c181840c | 200 | if (__close_nocancel (new_fd) != 0) |
ccfb2964 | 201 | goto fail; |
a5a6f926 UD |
202 | } |
203 | } | |
204 | break; | |
205 | ||
206 | case spawn_do_dup2: | |
db6b2f25 AZ |
207 | if (__dup2 (action->action.dup2_action.fd, |
208 | action->action.dup2_action.newfd) | |
08c7f6b0 | 209 | != action->action.dup2_action.newfd) |
ccfb2964 | 210 | goto fail; |
a5a6f926 | 211 | break; |
4a938cb2 FW |
212 | |
213 | case spawn_do_chdir: | |
214 | if (__chdir (action->action.chdir_action.path) != 0) | |
215 | goto fail; | |
216 | break; | |
3a3fb755 FW |
217 | |
218 | case spawn_do_fchdir: | |
219 | if (__fchdir (action->action.fchdir_action.fd) != 0) | |
220 | goto fail; | |
221 | break; | |
a5a6f926 UD |
222 | } |
223 | } | |
224 | } | |
225 | ||
ccfb2964 AZ |
226 | /* Set the initial signal mask of the child if POSIX_SPAWN_SETSIGMASK |
227 | is set, otherwise restore the previous one. */ | |
228 | __sigprocmask (SIG_SETMASK, (attr->__flags & POSIX_SPAWN_SETSIGMASK) | |
229 | ? &attr->__ss : &args->oldmask, 0); | |
a5a6f926 | 230 | |
ccfb2964 | 231 | args->exec (args->file, args->argv, args->envp); |
a5a6f926 | 232 | |
ccfb2964 AZ |
233 | /* This is compatibility function required to enable posix_spawn run |
234 | script without shebang definition for older posix_spawn versions | |
235 | (2.15). */ | |
236 | maybe_script_execute (args); | |
a5a6f926 | 237 | |
ccfb2964 | 238 | fail: |
db6b2f25 AZ |
239 | /* errno should have an appropriate non-zero value; otherwise, |
240 | there's a bug in glibc or the kernel. For lack of an error code | |
241 | (EINTERNALBUG) describing that, use ECHILD. Another option would | |
242 | be to set args->err to some negative sentinel and have the parent | |
243 | abort(), but that seems needlessly harsh. */ | |
244 | ret = errno ? : ECHILD; | |
ccfb2964 | 245 | if (ret) |
db6b2f25 | 246 | /* Since sizeof errno < PIPE_BUF, the write is atomic. */ |
c647fb88 | 247 | while (__write_nocancel (args->pipe[1], &ret, sizeof (ret)) < 0); |
a5a6f926 | 248 | |
ccfb2964 AZ |
249 | _exit (SPAWN_ERROR); |
250 | } | |
a5a6f926 | 251 | |
ccfb2964 AZ |
252 | /* Spawn a new process executing PATH with the attributes describes in *ATTRP. |
253 | Before running the process perform the actions described in FILE-ACTIONS. */ | |
254 | int | |
255 | __spawnix (pid_t *pid, const char *file, | |
256 | const posix_spawn_file_actions_t *file_actions, | |
257 | const posix_spawnattr_t *attrp, char *const argv[], | |
258 | char *const envp[], int xflags, | |
259 | int (*exec) (const char *, char *const *, char *const *)) | |
260 | { | |
261 | struct posix_spawn_args args; | |
262 | int ec; | |
a5a6f926 | 263 | |
ccfb2964 AZ |
264 | if (__pipe2 (args.pipe, O_CLOEXEC)) |
265 | return errno; | |
a5a6f926 | 266 | |
ccfb2964 AZ |
267 | /* Disable asynchronous cancellation. */ |
268 | int state; | |
269 | __libc_ptf_call (__pthread_setcancelstate, | |
270 | (PTHREAD_CANCEL_DISABLE, &state), 0); | |
a5a6f926 | 271 | |
ccfb2964 AZ |
272 | ptrdiff_t argc = 0; |
273 | ptrdiff_t limit = INT_MAX - 1; | |
274 | while (argv[argc++] != NULL) | |
275 | if (argc == limit) | |
276 | { | |
277 | errno = E2BIG; | |
278 | return errno; | |
279 | } | |
a5a6f926 | 280 | |
ccfb2964 AZ |
281 | args.file = file; |
282 | args.exec = exec; | |
283 | args.fa = file_actions; | |
284 | args.attr = attrp ? attrp : &(const posix_spawnattr_t) { 0 }; | |
285 | args.argv = argv; | |
286 | args.argc = argc; | |
287 | args.envp = envp; | |
288 | args.xflags = xflags; | |
289 | ||
290 | /* Generate the new process. */ | |
291 | pid_t new_pid = __fork (); | |
292 | ||
293 | if (new_pid == 0) | |
294 | __spawni_child (&args); | |
295 | else if (new_pid > 0) | |
296 | { | |
297 | __close (args.pipe[1]); | |
298 | ||
299 | if (__read (args.pipe[0], &ec, sizeof ec) != sizeof ec) | |
300 | ec = 0; | |
301 | else | |
302 | __waitpid (new_pid, &(int) { 0 }, 0); | |
a5a6f926 | 303 | } |
ccfb2964 | 304 | else |
db6b2f25 | 305 | ec = errno; |
a5a6f926 | 306 | |
ccfb2964 AZ |
307 | __close (args.pipe[0]); |
308 | ||
309 | if ((ec == 0) && (pid != NULL)) | |
310 | *pid = new_pid; | |
311 | ||
312 | __libc_ptf_call (__pthread_setcancelstate, (state, NULL), 0); | |
313 | ||
314 | return ec; | |
315 | } | |
316 | ||
317 | int | |
318 | __spawni (pid_t * pid, const char *file, | |
319 | const posix_spawn_file_actions_t * acts, | |
320 | const posix_spawnattr_t * attrp, char *const argv[], | |
321 | char *const envp[], int xflags) | |
322 | { | |
283d9851 AZ |
323 | /* It uses __execvpex to avoid run ENOEXEC in non compatibility mode (it |
324 | will be handled by maybe_script_execute). */ | |
ccfb2964 | 325 | return __spawnix (pid, file, acts, attrp, argv, envp, xflags, |
283d9851 | 326 | xflags & SPAWN_XFLAGS_USE_PATH ? __execvpex : __execve); |
a5a6f926 | 327 | } |