Merge remote-tracking branch 'remotes/elmarco/tags/libslirp-pull-request' 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 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_enablefips:
156 fips_set_state(true);
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 (pipe(fds) == -1) {
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 qemu_set_cloexec(daemon_pipe);
250
251 setsid();
252
253 pid = fork();
254 if (pid > 0) {
255 exit(0);
256 } else if (pid < 0) {
257 exit(1);
258 }
259 umask(027);
260
261 signal(SIGTSTP, SIG_IGN);
262 signal(SIGTTOU, SIG_IGN);
263 signal(SIGTTIN, SIG_IGN);
264 }
265 }
266
267 void os_setup_post(void)
268 {
269 int fd = 0;
270
271 if (daemonize) {
272 if (chdir("/")) {
273 error_report("not able to chdir to /: %s", strerror(errno));
274 exit(1);
275 }
276 TFR(fd = qemu_open_old("/dev/null", O_RDWR));
277 if (fd == -1) {
278 exit(1);
279 }
280 }
281
282 change_root();
283 change_process_uid();
284
285 if (daemonize) {
286 uint8_t status = 0;
287 ssize_t len;
288
289 dup2(fd, 0);
290 dup2(fd, 1);
291 /* In case -D is given do not redirect stderr to /dev/null */
292 if (!qemu_logfile) {
293 dup2(fd, 2);
294 }
295
296 close(fd);
297
298 do {
299 len = write(daemon_pipe, &status, 1);
300 } while (len < 0 && errno == EINTR);
301 if (len != 1) {
302 exit(1);
303 }
304 }
305 }
306
307 void os_set_line_buffering(void)
308 {
309 setvbuf(stdout, NULL, _IOLBF, 0);
310 }
311
312 bool is_daemonized(void)
313 {
314 return daemonize;
315 }
316
317 int os_mlock(void)
318 {
319 #ifdef HAVE_MLOCKALL
320 int ret = 0;
321
322 ret = mlockall(MCL_CURRENT | MCL_FUTURE);
323 if (ret < 0) {
324 error_report("mlockall: %s", strerror(errno));
325 }
326
327 return ret;
328 #else
329 return -ENOSYS;
330 #endif
331 }