Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' 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 #include "qemu-common.h"
33 /* Needed early for CONFIG_BSD etc. */
34 #include "net/slirp.h"
35 #include "qemu-options.h"
36 #include "qemu/error-report.h"
37 #include "qemu/log.h"
38 #include "sysemu/runstate.h"
39 #include "qemu/cutils.h"
40
41 #ifdef CONFIG_LINUX
42 #include <sys/prctl.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 /* Find a likely location for support files using the location of the binary.
84 For installed binaries this will be "$bindir/../share/qemu". When
85 running from the build tree this will be "$bindir/../pc-bios". */
86 #define SHARE_SUFFIX "/share/qemu"
87 #define BUILD_SUFFIX "/pc-bios"
88 char *os_find_datadir(void)
89 {
90 char *dir, *exec_dir;
91 char *res;
92 size_t max_len;
93
94 exec_dir = qemu_get_exec_dir();
95 if (exec_dir == NULL) {
96 return NULL;
97 }
98 dir = g_path_get_dirname(exec_dir);
99
100 max_len = strlen(dir) +
101 MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1;
102 res = g_malloc0(max_len);
103 snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX);
104 if (access(res, R_OK)) {
105 snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX);
106 if (access(res, R_OK)) {
107 g_free(res);
108 res = NULL;
109 }
110 }
111
112 g_free(dir);
113 g_free(exec_dir);
114 return res;
115 }
116 #undef SHARE_SUFFIX
117 #undef BUILD_SUFFIX
118
119 void os_set_proc_name(const char *s)
120 {
121 #if defined(PR_SET_NAME)
122 char name[16];
123 if (!s)
124 return;
125 pstrcpy(name, sizeof(name), s);
126 /* Could rewrite argv[0] too, but that's a bit more complicated.
127 This simple way is enough for `top'. */
128 if (prctl(PR_SET_NAME, name)) {
129 error_report("unable to change process name: %s", strerror(errno));
130 exit(1);
131 }
132 #else
133 error_report("Change of process name not supported by your OS");
134 exit(1);
135 #endif
136 }
137
138
139 static bool os_parse_runas_uid_gid(const char *optarg)
140 {
141 unsigned long lv;
142 const char *ep;
143 uid_t got_uid;
144 gid_t got_gid;
145 int rc;
146
147 rc = qemu_strtoul(optarg, &ep, 0, &lv);
148 got_uid = lv; /* overflow here is ID in C99 */
149 if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) {
150 return false;
151 }
152
153 rc = qemu_strtoul(ep + 1, 0, 0, &lv);
154 got_gid = lv; /* overflow here is ID in C99 */
155 if (rc || got_gid != lv || got_gid == (gid_t)-1) {
156 return false;
157 }
158
159 user_pwd = NULL;
160 user_uid = got_uid;
161 user_gid = got_gid;
162 return true;
163 }
164
165 /*
166 * Parse OS specific command line options.
167 * return 0 if option handled, -1 otherwise
168 */
169 int os_parse_cmd_args(int index, const char *optarg)
170 {
171 switch (index) {
172 case QEMU_OPTION_runas:
173 user_pwd = getpwnam(optarg);
174 if (user_pwd) {
175 user_uid = -1;
176 user_gid = -1;
177 } else if (!os_parse_runas_uid_gid(optarg)) {
178 error_report("User \"%s\" doesn't exist"
179 " (and is not <uid>:<gid>)",
180 optarg);
181 exit(1);
182 }
183 break;
184 case QEMU_OPTION_chroot:
185 chroot_dir = optarg;
186 break;
187 case QEMU_OPTION_daemonize:
188 daemonize = 1;
189 break;
190 #if defined(CONFIG_LINUX)
191 case QEMU_OPTION_enablefips:
192 fips_set_state(true);
193 break;
194 #endif
195 default:
196 return -1;
197 }
198
199 return 0;
200 }
201
202 static void change_process_uid(void)
203 {
204 assert((user_uid == (uid_t)-1) || user_pwd == NULL);
205 assert((user_uid == (uid_t)-1) ==
206 (user_gid == (gid_t)-1));
207
208 if (user_pwd || user_uid != (uid_t)-1) {
209 gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid;
210 uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid;
211 if (setgid(intended_gid) < 0) {
212 error_report("Failed to setgid(%d)", intended_gid);
213 exit(1);
214 }
215 if (user_pwd) {
216 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
217 error_report("Failed to initgroups(\"%s\", %d)",
218 user_pwd->pw_name, user_pwd->pw_gid);
219 exit(1);
220 }
221 } else {
222 if (setgroups(1, &user_gid) < 0) {
223 error_report("Failed to setgroups(1, [%d])",
224 user_gid);
225 exit(1);
226 }
227 }
228 if (setuid(intended_uid) < 0) {
229 error_report("Failed to setuid(%d)", intended_uid);
230 exit(1);
231 }
232 if (setuid(0) != -1) {
233 error_report("Dropping privileges failed");
234 exit(1);
235 }
236 }
237 }
238
239 static void change_root(void)
240 {
241 if (chroot_dir) {
242 if (chroot(chroot_dir) < 0) {
243 error_report("chroot failed");
244 exit(1);
245 }
246 if (chdir("/")) {
247 error_report("not able to chdir to /: %s", strerror(errno));
248 exit(1);
249 }
250 }
251
252 }
253
254 void os_daemonize(void)
255 {
256 if (daemonize) {
257 pid_t pid;
258 int fds[2];
259
260 if (pipe(fds) == -1) {
261 exit(1);
262 }
263
264 pid = fork();
265 if (pid > 0) {
266 uint8_t status;
267 ssize_t len;
268
269 close(fds[1]);
270
271 do {
272 len = read(fds[0], &status, 1);
273 } while (len < 0 && errno == EINTR);
274
275 /* only exit successfully if our child actually wrote
276 * a one-byte zero to our pipe, upon successful init */
277 exit(len == 1 && status == 0 ? 0 : 1);
278
279 } else if (pid < 0) {
280 exit(1);
281 }
282
283 close(fds[0]);
284 daemon_pipe = fds[1];
285 qemu_set_cloexec(daemon_pipe);
286
287 setsid();
288
289 pid = fork();
290 if (pid > 0) {
291 exit(0);
292 } else if (pid < 0) {
293 exit(1);
294 }
295 umask(027);
296
297 signal(SIGTSTP, SIG_IGN);
298 signal(SIGTTOU, SIG_IGN);
299 signal(SIGTTIN, SIG_IGN);
300 }
301 }
302
303 void os_setup_post(void)
304 {
305 int fd = 0;
306
307 if (daemonize) {
308 if (chdir("/")) {
309 error_report("not able to chdir to /: %s", strerror(errno));
310 exit(1);
311 }
312 TFR(fd = qemu_open("/dev/null", O_RDWR));
313 if (fd == -1) {
314 exit(1);
315 }
316 }
317
318 change_root();
319 change_process_uid();
320
321 if (daemonize) {
322 uint8_t status = 0;
323 ssize_t len;
324
325 dup2(fd, 0);
326 dup2(fd, 1);
327 /* In case -D is given do not redirect stderr to /dev/null */
328 if (!qemu_logfile) {
329 dup2(fd, 2);
330 }
331
332 close(fd);
333
334 do {
335 len = write(daemon_pipe, &status, 1);
336 } while (len < 0 && errno == EINTR);
337 if (len != 1) {
338 exit(1);
339 }
340 }
341 }
342
343 void os_set_line_buffering(void)
344 {
345 setvbuf(stdout, NULL, _IOLBF, 0);
346 }
347
348 bool is_daemonized(void)
349 {
350 return daemonize;
351 }
352
353 int os_mlock(void)
354 {
355 int ret = 0;
356
357 ret = mlockall(MCL_CURRENT | MCL_FUTURE);
358 if (ret < 0) {
359 error_report("mlockall: %s", strerror(errno));
360 }
361
362 return ret;
363 }