Merge tag 'for-upstream' of https://repo.or.cz/qemu/kevin into staging
[qemu.git] / os-posix.c
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
40 #ifdef CONFIG_LINUX
41 #include <sys/prctl.h>
42 #include "qemu/async-teardown.h"
43 #endif
44
45 /*
46 * Must set all three of these at once.
47 * Legal combinations are unset by name by uid
48 */
49 static struct passwd *user_pwd; /* NULL non-NULL NULL */
50 static uid_t user_uid = (uid_t)-1; /* -1 -1 >=0 */
51 static gid_t user_gid = (gid_t)-1; /* -1 -1 >=0 */
52
53 static const char *chroot_dir;
54 static int daemonize;
55 static int daemon_pipe;
56
57 void os_setup_early_signal_handling(void)
58 {
59 struct sigaction act;
60 sigfillset(&act.sa_mask);
61 act.sa_flags = 0;
62 act.sa_handler = SIG_IGN;
63 sigaction(SIGPIPE, &act, NULL);
64 }
65
66 static void termsig_handler(int signal, siginfo_t *info, void *c)
67 {
68 qemu_system_killed(info->si_signo, info->si_pid);
69 }
70
71 void os_setup_signal_handling(void)
72 {
73 struct sigaction act;
74
75 memset(&act, 0, sizeof(act));
76 act.sa_sigaction = termsig_handler;
77 act.sa_flags = SA_SIGINFO;
78 sigaction(SIGINT, &act, NULL);
79 sigaction(SIGHUP, &act, NULL);
80 sigaction(SIGTERM, &act, NULL);
81 }
82
83 void os_set_proc_name(const char *s)
84 {
85 #if defined(PR_SET_NAME)
86 char name[16];
87 if (!s)
88 return;
89 pstrcpy(name, sizeof(name), s);
90 /* Could rewrite argv[0] too, but that's a bit more complicated.
91 This simple way is enough for `top'. */
92 if (prctl(PR_SET_NAME, name)) {
93 error_report("unable to change process name: %s", strerror(errno));
94 exit(1);
95 }
96 #else
97 error_report("Change of process name not supported by your OS");
98 exit(1);
99 #endif
100 }
101
102
103 static bool os_parse_runas_uid_gid(const char *optarg)
104 {
105 unsigned long lv;
106 const char *ep;
107 uid_t got_uid;
108 gid_t got_gid;
109 int rc;
110
111 rc = qemu_strtoul(optarg, &ep, 0, &lv);
112 got_uid = lv; /* overflow here is ID in C99 */
113 if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) {
114 return false;
115 }
116
117 rc = qemu_strtoul(ep + 1, 0, 0, &lv);
118 got_gid = lv; /* overflow here is ID in C99 */
119 if (rc || got_gid != lv || got_gid == (gid_t)-1) {
120 return false;
121 }
122
123 user_pwd = NULL;
124 user_uid = got_uid;
125 user_gid = got_gid;
126 return true;
127 }
128
129 /*
130 * Parse OS specific command line options.
131 * return 0 if option handled, -1 otherwise
132 */
133 int os_parse_cmd_args(int index, const char *optarg)
134 {
135 switch (index) {
136 case QEMU_OPTION_runas:
137 user_pwd = getpwnam(optarg);
138 if (user_pwd) {
139 user_uid = -1;
140 user_gid = -1;
141 } else if (!os_parse_runas_uid_gid(optarg)) {
142 error_report("User \"%s\" doesn't exist"
143 " (and is not <uid>:<gid>)",
144 optarg);
145 exit(1);
146 }
147 break;
148 case QEMU_OPTION_chroot:
149 chroot_dir = optarg;
150 break;
151 case QEMU_OPTION_daemonize:
152 daemonize = 1;
153 break;
154 #if defined(CONFIG_LINUX)
155 case QEMU_OPTION_asyncteardown:
156 init_async_teardown();
157 break;
158 #endif
159 default:
160 return -1;
161 }
162
163 return 0;
164 }
165
166 static void change_process_uid(void)
167 {
168 assert((user_uid == (uid_t)-1) || user_pwd == NULL);
169 assert((user_uid == (uid_t)-1) ==
170 (user_gid == (gid_t)-1));
171
172 if (user_pwd || user_uid != (uid_t)-1) {
173 gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid;
174 uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid;
175 if (setgid(intended_gid) < 0) {
176 error_report("Failed to setgid(%d)", intended_gid);
177 exit(1);
178 }
179 if (user_pwd) {
180 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
181 error_report("Failed to initgroups(\"%s\", %d)",
182 user_pwd->pw_name, user_pwd->pw_gid);
183 exit(1);
184 }
185 } else {
186 if (setgroups(1, &user_gid) < 0) {
187 error_report("Failed to setgroups(1, [%d])",
188 user_gid);
189 exit(1);
190 }
191 }
192 if (setuid(intended_uid) < 0) {
193 error_report("Failed to setuid(%d)", intended_uid);
194 exit(1);
195 }
196 if (setuid(0) != -1) {
197 error_report("Dropping privileges failed");
198 exit(1);
199 }
200 }
201 }
202
203 static void change_root(void)
204 {
205 if (chroot_dir) {
206 if (chroot(chroot_dir) < 0) {
207 error_report("chroot failed");
208 exit(1);
209 }
210 if (chdir("/")) {
211 error_report("not able to chdir to /: %s", strerror(errno));
212 exit(1);
213 }
214 }
215
216 }
217
218 void os_daemonize(void)
219 {
220 if (daemonize) {
221 pid_t pid;
222 int fds[2];
223
224 if (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) {
225 exit(1);
226 }
227
228 pid = fork();
229 if (pid > 0) {
230 uint8_t status;
231 ssize_t len;
232
233 close(fds[1]);
234
235 do {
236 len = read(fds[0], &status, 1);
237 } while (len < 0 && errno == EINTR);
238
239 /* only exit successfully if our child actually wrote
240 * a one-byte zero to our pipe, upon successful init */
241 exit(len == 1 && status == 0 ? 0 : 1);
242
243 } else if (pid < 0) {
244 exit(1);
245 }
246
247 close(fds[0]);
248 daemon_pipe = fds[1];
249
250 setsid();
251
252 pid = fork();
253 if (pid > 0) {
254 exit(0);
255 } else if (pid < 0) {
256 exit(1);
257 }
258 umask(027);
259
260 signal(SIGTSTP, SIG_IGN);
261 signal(SIGTTOU, SIG_IGN);
262 signal(SIGTTIN, SIG_IGN);
263 }
264 }
265
266 void os_setup_post(void)
267 {
268 int fd = 0;
269
270 if (daemonize) {
271 if (chdir("/")) {
272 error_report("not able to chdir to /: %s", strerror(errno));
273 exit(1);
274 }
275 fd = RETRY_ON_EINTR(qemu_open_old("/dev/null", O_RDWR));
276 if (fd == -1) {
277 exit(1);
278 }
279 }
280
281 change_root();
282 change_process_uid();
283
284 if (daemonize) {
285 uint8_t status = 0;
286 ssize_t len;
287
288 dup2(fd, 0);
289 dup2(fd, 1);
290 /* In case -D is given do not redirect stderr to /dev/null */
291 if (!qemu_log_enabled()) {
292 dup2(fd, 2);
293 }
294
295 close(fd);
296
297 do {
298 len = write(daemon_pipe, &status, 1);
299 } while (len < 0 && errno == EINTR);
300 if (len != 1) {
301 exit(1);
302 }
303 }
304 }
305
306 void os_set_line_buffering(void)
307 {
308 setvbuf(stdout, NULL, _IOLBF, 0);
309 }
310
311 bool is_daemonized(void)
312 {
313 return daemonize;
314 }
315
316 int os_set_daemonize(bool d)
317 {
318 daemonize = d;
319 return 0;
320 }
321
322 int os_mlock(void)
323 {
324 #ifdef HAVE_MLOCKALL
325 int ret = 0;
326
327 ret = mlockall(MCL_CURRENT | MCL_FUTURE);
328 if (ret < 0) {
329 error_report("mlockall: %s", strerror(errno));
330 }
331
332 return ret;
333 #else
334 return -ENOSYS;
335 #endif
336 }