1 | /* Guts of POSIX spawn interface. Generic POSIX.1 version. |
2 | Copyright (C) 2000-2016 Free Software Foundation, Inc. |
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 |
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. |
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 |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <errno.h> |
20 | #include <fcntl.h> |
21 | #include <paths.h> |
22 | #include <spawn.h> |
23 | #include <stdbool.h> |
24 | #include <stdlib.h> |
25 | #include <string.h> |
26 | #include <unistd.h> |
27 | #include <signal.h> |
28 | #include <sys/resource.h> |
29 | #include "spawn_int.h" |
30 | #include <not-cancel.h> |
31 | #include <local-setxid.h> |
32 | #include <shlib-compat.h> |
33 | |
34 | |
35 | /* The Unix standard contains a long explanation of the way to signal |
36 | an error after the fork() was successful. Since no new wait status |
37 | was wanted there is no way to signal an error using one of the |
38 | available methods. The committee chose to signal an error by a |
39 | normal program exit with the exit code 127. */ |
40 | #define SPAWN_ERROR 127 |
41 | |
42 | |
43 | /* The file is accessible but it is not an executable file. Invoke |
44 | the shell to interpret it as a script. */ |
45 | static void |
46 | internal_function |
47 | script_execute (const char *file, char *const argv[], char *const envp[]) |
48 | { |
49 | /* Count the arguments. */ |
50 | int argc = 0; |
51 | while (argv[argc++]) |
52 | ; |
53 | |
54 | /* Construct an argument list for the shell. */ |
55 | { |
56 | char *new_argv[argc + 1]; |
57 | new_argv[0] = (char *) _PATH_BSHELL; |
58 | new_argv[1] = (char *) file; |
59 | while (argc > 1) |
60 | { |
61 | new_argv[argc] = argv[argc - 1]; |
62 | --argc; |
63 | } |
64 | |
65 | /* Execute the shell. */ |
66 | __execve (new_argv[0], new_argv, envp); |
67 | } |
68 | } |
69 | |
70 | static inline void |
71 | maybe_script_execute (const char *file, char *const argv[], char *const envp[], |
72 | int xflags) |
73 | { |
74 | if (SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_15) |
75 | && (xflags & SPAWN_XFLAGS_TRY_SHELL) |
76 | && errno == ENOEXEC) |
77 | script_execute (file, argv, envp); |
78 | } |
79 | |
80 | /* Spawn a new process executing PATH with the attributes describes in *ATTRP. |
81 | Before running the process perform the actions described in FILE-ACTIONS. */ |
82 | int |
83 | __spawni (pid_t *pid, const char *file, |
84 | const posix_spawn_file_actions_t *file_actions, |
85 | const posix_spawnattr_t *attrp, char *const argv[], |
86 | char *const envp[], int xflags) |
87 | { |
88 | pid_t new_pid; |
89 | char *path, *p, *name; |
90 | size_t len; |
91 | size_t pathlen; |
92 | |
93 | /* Do this once. */ |
94 | short int flags = attrp == NULL ? 0 : attrp->__flags; |
95 | |
96 | /* Generate the new process. */ |
97 | if ((flags & POSIX_SPAWN_USEVFORK) != 0 |
98 | /* If no major work is done, allow using vfork. Note that we |
99 | might perform the path searching. But this would be done by |
100 | a call to execvp(), too, and such a call must be OK according |
101 | to POSIX. */ |
102 | || ((flags & (POSIX_SPAWN_SETSIGMASK | POSIX_SPAWN_SETSIGDEF |
103 | | POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER |
104 | | POSIX_SPAWN_SETPGROUP | POSIX_SPAWN_RESETIDS)) == 0 |
105 | && file_actions == NULL)) |
106 | new_pid = __vfork (); |
107 | else |
108 | new_pid = __fork (); |
109 | |
110 | if (new_pid != 0) |
111 | { |
112 | if (new_pid < 0) |
113 | return errno; |
114 | |
115 | /* The call was successful. Store the PID if necessary. */ |
116 | if (pid != NULL) |
117 | *pid = new_pid; |
118 | |
119 | return 0; |
120 | } |
121 | |
122 | /* Set signal mask. */ |
123 | if ((flags & POSIX_SPAWN_SETSIGMASK) != 0 |
124 | && __sigprocmask (SIG_SETMASK, &attrp->__ss, NULL) != 0) |
125 | _exit (SPAWN_ERROR); |
126 | |
127 | /* Set signal default action. */ |
128 | if ((flags & POSIX_SPAWN_SETSIGDEF) != 0) |
129 | { |
130 | /* We have to iterate over all signals. This could possibly be |
131 | done better but it requires system specific solutions since |
132 | the sigset_t data type can be very different on different |
133 | architectures. */ |
134 | int sig; |
135 | struct sigaction sa; |
136 | |
137 | memset (&sa, '\0', sizeof (sa)); |
138 | sa.sa_handler = SIG_DFL; |
139 | |
140 | for (sig = 1; sig <= _NSIG; ++sig) |
141 | if (__sigismember (&attrp->__sd, sig) != 0 |
142 | && __sigaction (sig, &sa, NULL) != 0) |
143 | _exit (SPAWN_ERROR); |
144 | |
145 | } |
146 | |
147 | #ifdef _POSIX_PRIORITY_SCHEDULING |
148 | /* Set the scheduling algorithm and parameters. */ |
149 | if ((flags & (POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER)) |
150 | == POSIX_SPAWN_SETSCHEDPARAM) |
151 | { |
152 | if (__sched_setparam (0, &attrp->__sp) == -1) |
153 | _exit (SPAWN_ERROR); |
154 | } |
155 | else if ((flags & POSIX_SPAWN_SETSCHEDULER) != 0) |
156 | { |
157 | if (__sched_setscheduler (0, attrp->__policy, &attrp->__sp) == -1) |
158 | _exit (SPAWN_ERROR); |
159 | } |
160 | #endif |
161 | |
162 | /* Set the process group ID. */ |
163 | if ((flags & POSIX_SPAWN_SETPGROUP) != 0 |
164 | && __setpgid (0, attrp->__pgrp) != 0) |
165 | _exit (SPAWN_ERROR); |
166 | |
167 | /* Set the effective user and group IDs. */ |
168 | if ((flags & POSIX_SPAWN_RESETIDS) != 0 |
169 | && (local_seteuid (__getuid ()) != 0 |
170 | || local_setegid (__getgid ()) != 0)) |
171 | _exit (SPAWN_ERROR); |
172 | |
173 | /* Execute the file actions. */ |
174 | if (file_actions != NULL) |
175 | { |
176 | int cnt; |
177 | struct rlimit64 fdlimit; |
178 | bool have_fdlimit = false; |
179 | |
180 | for (cnt = 0; cnt < file_actions->__used; ++cnt) |
181 | { |
182 | struct __spawn_action *action = &file_actions->__actions[cnt]; |
183 | |
184 | switch (action->tag) |
185 | { |
186 | case spawn_do_close: |
187 | if (close_not_cancel (action->action.close_action.fd) != 0) |
188 | { |
189 | if (! have_fdlimit) |
190 | { |
191 | __getrlimit64 (RLIMIT_NOFILE, &fdlimit); |
192 | have_fdlimit = true; |
193 | } |
194 | |
195 | /* Only signal errors for file descriptors out of range. */ |
196 | if (action->action.close_action.fd < 0 |
197 | || action->action.close_action.fd >= fdlimit.rlim_cur) |
198 | /* Signal the error. */ |
199 | _exit (SPAWN_ERROR); |
200 | } |
201 | break; |
202 | |
203 | case spawn_do_open: |
204 | { |
205 | int new_fd = open_not_cancel (action->action.open_action.path, |
206 | action->action.open_action.oflag |
207 | | O_LARGEFILE, |
208 | action->action.open_action.mode); |
209 | |
210 | if (new_fd == -1) |
211 | /* The `open' call failed. */ |
212 | _exit (SPAWN_ERROR); |
213 | |
214 | /* Make sure the desired file descriptor is used. */ |
215 | if (new_fd != action->action.open_action.fd) |
216 | { |
217 | if (__dup2 (new_fd, action->action.open_action.fd) |
218 | != action->action.open_action.fd) |
219 | /* The `dup2' call failed. */ |
220 | _exit (SPAWN_ERROR); |
221 | |
222 | if (close_not_cancel (new_fd) != 0) |
223 | /* The `close' call failed. */ |
224 | _exit (SPAWN_ERROR); |
225 | } |
226 | } |
227 | break; |
228 | |
229 | case spawn_do_dup2: |
230 | if (__dup2 (action->action.dup2_action.fd, |
231 | action->action.dup2_action.newfd) |
232 | != action->action.dup2_action.newfd) |
233 | /* The `dup2' call failed. */ |
234 | _exit (SPAWN_ERROR); |
235 | break; |
236 | } |
237 | } |
238 | } |
239 | |
240 | if ((xflags & SPAWN_XFLAGS_USE_PATH) == 0 || strchr (file, '/') != NULL) |
241 | { |
242 | /* The FILE parameter is actually a path. */ |
243 | __execve (file, argv, envp); |
244 | |
245 | maybe_script_execute (file, argv, envp, xflags); |
246 | |
247 | /* Oh, oh. `execve' returns. This is bad. */ |
248 | _exit (SPAWN_ERROR); |
249 | } |
250 | |
251 | /* We have to search for FILE on the path. */ |
252 | path = getenv ("PATH" ); |
253 | if (path == NULL) |
254 | { |
255 | /* There is no `PATH' in the environment. |
256 | The default search path is the current directory |
257 | followed by the path `confstr' returns for `_CS_PATH'. */ |
258 | len = confstr (_CS_PATH, (char *) NULL, 0); |
259 | path = (char *) __alloca (1 + len); |
260 | path[0] = ':'; |
261 | (void) confstr (_CS_PATH, path + 1, len); |
262 | } |
263 | |
264 | len = strlen (file) + 1; |
265 | pathlen = strlen (path); |
266 | name = __alloca (pathlen + len + 1); |
267 | /* Copy the file name at the top. */ |
268 | name = (char *) memcpy (name + pathlen + 1, file, len); |
269 | /* And add the slash. */ |
270 | *--name = '/'; |
271 | |
272 | p = path; |
273 | do |
274 | { |
275 | char *startp; |
276 | |
277 | path = p; |
278 | p = __strchrnul (path, ':'); |
279 | |
280 | if (p == path) |
281 | /* Two adjacent colons, or a colon at the beginning or the end |
282 | of `PATH' means to search the current directory. */ |
283 | startp = name + 1; |
284 | else |
285 | startp = (char *) memcpy (name - (p - path), path, p - path); |
286 | |
287 | /* Try to execute this name. If it works, execv will not return. */ |
288 | __execve (startp, argv, envp); |
289 | |
290 | maybe_script_execute (startp, argv, envp, xflags); |
291 | |
292 | switch (errno) |
293 | { |
294 | case EACCES: |
295 | case ENOENT: |
296 | case ESTALE: |
297 | case ENOTDIR: |
298 | /* Those errors indicate the file is missing or not executable |
299 | by us, in which case we want to just try the next path |
300 | directory. */ |
301 | break; |
302 | |
303 | default: |
304 | /* Some other error means we found an executable file, but |
305 | something went wrong executing it; return the error to our |
306 | caller. */ |
307 | _exit (SPAWN_ERROR); |
308 | } |
309 | } |
310 | while (*p++ != '\0'); |
311 | |
312 | /* Return with an error. */ |
313 | _exit (SPAWN_ERROR); |
314 | } |
315 | |