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1 | /* | |
2 | * os-posix.c | |
3 | * | |
4 | * Copyright (c) 2003-2008 Fabrice Bellard | |
5 | * Copyright (c) 2010 Red Hat, Inc. | |
6 | * | |
7 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
8 | * of this software and associated documentation files (the "Software"), to deal | |
9 | * in the Software without restriction, including without limitation the rights | |
10 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
11 | * copies of the Software, and to permit persons to whom the Software is | |
12 | * furnished to do so, subject to the following conditions: | |
13 | * | |
14 | * The above copyright notice and this permission notice shall be included in | |
15 | * all copies or substantial portions of the Software. | |
16 | * | |
17 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
18 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
19 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL | |
20 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
21 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
22 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | |
23 | * THE SOFTWARE. | |
24 | */ | |
25 | ||
26 | #include "qemu/osdep.h" | |
27 | #include <sys/wait.h> | |
28 | #include <pwd.h> | |
29 | #include <grp.h> | |
30 | #include <libgen.h> | |
31 | ||
32 | /* Needed early for CONFIG_BSD etc. */ | |
33 | #include "net/slirp.h" | |
34 | #include "qemu/qemu-options.h" | |
35 | #include "qemu/error-report.h" | |
36 | #include "qemu/log.h" | |
37 | #include "sysemu/runstate.h" | |
38 | #include "qemu/cutils.h" | |
39 | #include "qemu/config-file.h" | |
40 | #include "qemu/option.h" | |
41 | #include "qemu/module.h" | |
42 | ||
43 | #ifdef CONFIG_LINUX | |
44 | #include <sys/prctl.h> | |
45 | #include "qemu/async-teardown.h" | |
46 | #endif | |
47 | ||
48 | /* | |
49 | * Must set all three of these at once. | |
50 | * Legal combinations are unset by name by uid | |
51 | */ | |
52 | static struct passwd *user_pwd; /* NULL non-NULL NULL */ | |
53 | static uid_t user_uid = (uid_t)-1; /* -1 -1 >=0 */ | |
54 | static gid_t user_gid = (gid_t)-1; /* -1 -1 >=0 */ | |
55 | ||
56 | static const char *chroot_dir; | |
57 | static int daemonize; | |
58 | static int daemon_pipe; | |
59 | ||
60 | void os_setup_early_signal_handling(void) | |
61 | { | |
62 | struct sigaction act; | |
63 | sigfillset(&act.sa_mask); | |
64 | act.sa_flags = 0; | |
65 | act.sa_handler = SIG_IGN; | |
66 | sigaction(SIGPIPE, &act, NULL); | |
67 | } | |
68 | ||
69 | static void termsig_handler(int signal, siginfo_t *info, void *c) | |
70 | { | |
71 | qemu_system_killed(info->si_signo, info->si_pid); | |
72 | } | |
73 | ||
74 | void os_setup_signal_handling(void) | |
75 | { | |
76 | struct sigaction act; | |
77 | ||
78 | memset(&act, 0, sizeof(act)); | |
79 | act.sa_sigaction = termsig_handler; | |
80 | act.sa_flags = SA_SIGINFO; | |
81 | sigaction(SIGINT, &act, NULL); | |
82 | sigaction(SIGHUP, &act, NULL); | |
83 | sigaction(SIGTERM, &act, NULL); | |
84 | } | |
85 | ||
86 | void os_set_proc_name(const char *s) | |
87 | { | |
88 | #if defined(PR_SET_NAME) | |
89 | char name[16]; | |
90 | if (!s) | |
91 | return; | |
92 | pstrcpy(name, sizeof(name), s); | |
93 | /* Could rewrite argv[0] too, but that's a bit more complicated. | |
94 | This simple way is enough for `top'. */ | |
95 | if (prctl(PR_SET_NAME, name)) { | |
96 | error_report("unable to change process name: %s", strerror(errno)); | |
97 | exit(1); | |
98 | } | |
99 | #else | |
100 | error_report("Change of process name not supported by your OS"); | |
101 | exit(1); | |
102 | #endif | |
103 | } | |
104 | ||
105 | ||
106 | static bool os_parse_runas_uid_gid(const char *optarg) | |
107 | { | |
108 | unsigned long lv; | |
109 | const char *ep; | |
110 | uid_t got_uid; | |
111 | gid_t got_gid; | |
112 | int rc; | |
113 | ||
114 | rc = qemu_strtoul(optarg, &ep, 0, &lv); | |
115 | got_uid = lv; /* overflow here is ID in C99 */ | |
116 | if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) { | |
117 | return false; | |
118 | } | |
119 | ||
120 | rc = qemu_strtoul(ep + 1, 0, 0, &lv); | |
121 | got_gid = lv; /* overflow here is ID in C99 */ | |
122 | if (rc || got_gid != lv || got_gid == (gid_t)-1) { | |
123 | return false; | |
124 | } | |
125 | ||
126 | user_pwd = NULL; | |
127 | user_uid = got_uid; | |
128 | user_gid = got_gid; | |
129 | return true; | |
130 | } | |
131 | ||
132 | /* | |
133 | * Parse OS specific command line options. | |
134 | * return 0 if option handled, -1 otherwise | |
135 | */ | |
136 | int os_parse_cmd_args(int index, const char *optarg) | |
137 | { | |
138 | switch (index) { | |
139 | case QEMU_OPTION_runas: | |
140 | user_pwd = getpwnam(optarg); | |
141 | if (user_pwd) { | |
142 | user_uid = -1; | |
143 | user_gid = -1; | |
144 | } else if (!os_parse_runas_uid_gid(optarg)) { | |
145 | error_report("User \"%s\" doesn't exist" | |
146 | " (and is not <uid>:<gid>)", | |
147 | optarg); | |
148 | exit(1); | |
149 | } | |
150 | break; | |
151 | case QEMU_OPTION_chroot: | |
152 | warn_report("option is deprecated, use '-run-with chroot=...' instead"); | |
153 | chroot_dir = optarg; | |
154 | break; | |
155 | case QEMU_OPTION_daemonize: | |
156 | daemonize = 1; | |
157 | break; | |
158 | #if defined(CONFIG_LINUX) | |
159 | /* deprecated */ | |
160 | case QEMU_OPTION_asyncteardown: | |
161 | init_async_teardown(); | |
162 | break; | |
163 | #endif | |
164 | case QEMU_OPTION_run_with: { | |
165 | const char *str; | |
166 | QemuOpts *opts = qemu_opts_parse_noisily(qemu_find_opts("run-with"), | |
167 | optarg, false); | |
168 | if (!opts) { | |
169 | exit(1); | |
170 | } | |
171 | #if defined(CONFIG_LINUX) | |
172 | if (qemu_opt_get_bool(opts, "async-teardown", false)) { | |
173 | init_async_teardown(); | |
174 | } | |
175 | #endif | |
176 | str = qemu_opt_get(opts, "chroot"); | |
177 | if (str) { | |
178 | chroot_dir = str; | |
179 | } | |
180 | break; | |
181 | } | |
182 | default: | |
183 | return -1; | |
184 | } | |
185 | ||
186 | return 0; | |
187 | } | |
188 | ||
189 | static void change_process_uid(void) | |
190 | { | |
191 | assert((user_uid == (uid_t)-1) || user_pwd == NULL); | |
192 | assert((user_uid == (uid_t)-1) == | |
193 | (user_gid == (gid_t)-1)); | |
194 | ||
195 | if (user_pwd || user_uid != (uid_t)-1) { | |
196 | gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid; | |
197 | uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid; | |
198 | if (setgid(intended_gid) < 0) { | |
199 | error_report("Failed to setgid(%d)", intended_gid); | |
200 | exit(1); | |
201 | } | |
202 | if (user_pwd) { | |
203 | if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { | |
204 | error_report("Failed to initgroups(\"%s\", %d)", | |
205 | user_pwd->pw_name, user_pwd->pw_gid); | |
206 | exit(1); | |
207 | } | |
208 | } else { | |
209 | if (setgroups(1, &user_gid) < 0) { | |
210 | error_report("Failed to setgroups(1, [%d])", | |
211 | user_gid); | |
212 | exit(1); | |
213 | } | |
214 | } | |
215 | if (setuid(intended_uid) < 0) { | |
216 | error_report("Failed to setuid(%d)", intended_uid); | |
217 | exit(1); | |
218 | } | |
219 | if (setuid(0) != -1) { | |
220 | error_report("Dropping privileges failed"); | |
221 | exit(1); | |
222 | } | |
223 | } | |
224 | } | |
225 | ||
226 | static void change_root(void) | |
227 | { | |
228 | if (chroot_dir) { | |
229 | if (chroot(chroot_dir) < 0) { | |
230 | error_report("chroot failed"); | |
231 | exit(1); | |
232 | } | |
233 | if (chdir("/")) { | |
234 | error_report("not able to chdir to /: %s", strerror(errno)); | |
235 | exit(1); | |
236 | } | |
237 | } | |
238 | ||
239 | } | |
240 | ||
241 | void os_daemonize(void) | |
242 | { | |
243 | if (daemonize) { | |
244 | pid_t pid; | |
245 | int fds[2]; | |
246 | ||
247 | if (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) { | |
248 | exit(1); | |
249 | } | |
250 | ||
251 | pid = fork(); | |
252 | if (pid > 0) { | |
253 | uint8_t status; | |
254 | ssize_t len; | |
255 | ||
256 | close(fds[1]); | |
257 | ||
258 | do { | |
259 | len = read(fds[0], &status, 1); | |
260 | } while (len < 0 && errno == EINTR); | |
261 | ||
262 | /* only exit successfully if our child actually wrote | |
263 | * a one-byte zero to our pipe, upon successful init */ | |
264 | exit(len == 1 && status == 0 ? 0 : 1); | |
265 | ||
266 | } else if (pid < 0) { | |
267 | exit(1); | |
268 | } | |
269 | ||
270 | close(fds[0]); | |
271 | daemon_pipe = fds[1]; | |
272 | ||
273 | setsid(); | |
274 | ||
275 | pid = fork(); | |
276 | if (pid > 0) { | |
277 | exit(0); | |
278 | } else if (pid < 0) { | |
279 | exit(1); | |
280 | } | |
281 | umask(027); | |
282 | ||
283 | signal(SIGTSTP, SIG_IGN); | |
284 | signal(SIGTTOU, SIG_IGN); | |
285 | signal(SIGTTIN, SIG_IGN); | |
286 | } | |
287 | } | |
288 | ||
289 | void os_setup_post(void) | |
290 | { | |
291 | int fd = 0; | |
292 | ||
293 | if (daemonize) { | |
294 | if (chdir("/")) { | |
295 | error_report("not able to chdir to /: %s", strerror(errno)); | |
296 | exit(1); | |
297 | } | |
298 | fd = RETRY_ON_EINTR(qemu_open_old("/dev/null", O_RDWR)); | |
299 | if (fd == -1) { | |
300 | exit(1); | |
301 | } | |
302 | } | |
303 | ||
304 | change_root(); | |
305 | change_process_uid(); | |
306 | ||
307 | if (daemonize) { | |
308 | uint8_t status = 0; | |
309 | ssize_t len; | |
310 | ||
311 | dup2(fd, 0); | |
312 | dup2(fd, 1); | |
313 | /* In case -D is given do not redirect stderr to /dev/null */ | |
314 | if (!qemu_log_enabled()) { | |
315 | dup2(fd, 2); | |
316 | } | |
317 | ||
318 | close(fd); | |
319 | ||
320 | do { | |
321 | len = write(daemon_pipe, &status, 1); | |
322 | } while (len < 0 && errno == EINTR); | |
323 | if (len != 1) { | |
324 | exit(1); | |
325 | } | |
326 | } | |
327 | } | |
328 | ||
329 | void os_set_line_buffering(void) | |
330 | { | |
331 | setvbuf(stdout, NULL, _IOLBF, 0); | |
332 | } | |
333 | ||
334 | bool is_daemonized(void) | |
335 | { | |
336 | return daemonize; | |
337 | } | |
338 | ||
339 | int os_set_daemonize(bool d) | |
340 | { | |
341 | daemonize = d; | |
342 | return 0; | |
343 | } | |
344 | ||
345 | int os_mlock(void) | |
346 | { | |
347 | #ifdef HAVE_MLOCKALL | |
348 | int ret = 0; | |
349 | ||
350 | ret = mlockall(MCL_CURRENT | MCL_FUTURE); | |
351 | if (ret < 0) { | |
352 | error_report("mlockall: %s", strerror(errno)); | |
353 | } | |
354 | ||
355 | return ret; | |
356 | #else | |
357 | return -ENOSYS; | |
358 | #endif | |
359 | } | |
360 | ||
361 | static QemuOptsList qemu_run_with_opts = { | |
362 | .name = "run-with", | |
363 | .head = QTAILQ_HEAD_INITIALIZER(qemu_run_with_opts.head), | |
364 | .desc = { | |
365 | #if defined(CONFIG_LINUX) | |
366 | { | |
367 | .name = "async-teardown", | |
368 | .type = QEMU_OPT_BOOL, | |
369 | }, | |
370 | #endif | |
371 | { | |
372 | .name = "chroot", | |
373 | .type = QEMU_OPT_STRING, | |
374 | }, | |
375 | { /* end of list */ } | |
376 | }, | |
377 | }; | |
378 | ||
379 | static void register_runwith(void) | |
380 | { | |
381 | qemu_add_opts(&qemu_run_with_opts); | |
382 | } | |
383 | opts_init(register_runwith); |