Merge tag 'pull-target-arm-20220812' of https://git.linaro.org/people/pmaydell/qemu...
[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 #endif
43
44 /*
45 * Must set all three of these at once.
46 * Legal combinations are unset by name by uid
47 */
48 static struct passwd *user_pwd; /* NULL non-NULL NULL */
49 static uid_t user_uid = (uid_t)-1; /* -1 -1 >=0 */
50 static gid_t user_gid = (gid_t)-1; /* -1 -1 >=0 */
51
52 static const char *chroot_dir;
53 static int daemonize;
54 static int daemon_pipe;
55
56 void os_setup_early_signal_handling(void)
57 {
58 struct sigaction act;
59 sigfillset(&act.sa_mask);
60 act.sa_flags = 0;
61 act.sa_handler = SIG_IGN;
62 sigaction(SIGPIPE, &act, NULL);
63 }
64
65 static void termsig_handler(int signal, siginfo_t *info, void *c)
66 {
67 qemu_system_killed(info->si_signo, info->si_pid);
68 }
69
70 void os_setup_signal_handling(void)
71 {
72 struct sigaction act;
73
74 memset(&act, 0, sizeof(act));
75 act.sa_sigaction = termsig_handler;
76 act.sa_flags = SA_SIGINFO;
77 sigaction(SIGINT, &act, NULL);
78 sigaction(SIGHUP, &act, NULL);
79 sigaction(SIGTERM, &act, NULL);
80 }
81
82 void os_set_proc_name(const char *s)
83 {
84 #if defined(PR_SET_NAME)
85 char name[16];
86 if (!s)
87 return;
88 pstrcpy(name, sizeof(name), s);
89 /* Could rewrite argv[0] too, but that's a bit more complicated.
90 This simple way is enough for `top'. */
91 if (prctl(PR_SET_NAME, name)) {
92 error_report("unable to change process name: %s", strerror(errno));
93 exit(1);
94 }
95 #else
96 error_report("Change of process name not supported by your OS");
97 exit(1);
98 #endif
99 }
100
101
102 static bool os_parse_runas_uid_gid(const char *optarg)
103 {
104 unsigned long lv;
105 const char *ep;
106 uid_t got_uid;
107 gid_t got_gid;
108 int rc;
109
110 rc = qemu_strtoul(optarg, &ep, 0, &lv);
111 got_uid = lv; /* overflow here is ID in C99 */
112 if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) {
113 return false;
114 }
115
116 rc = qemu_strtoul(ep + 1, 0, 0, &lv);
117 got_gid = lv; /* overflow here is ID in C99 */
118 if (rc || got_gid != lv || got_gid == (gid_t)-1) {
119 return false;
120 }
121
122 user_pwd = NULL;
123 user_uid = got_uid;
124 user_gid = got_gid;
125 return true;
126 }
127
128 /*
129 * Parse OS specific command line options.
130 * return 0 if option handled, -1 otherwise
131 */
132 int os_parse_cmd_args(int index, const char *optarg)
133 {
134 switch (index) {
135 case QEMU_OPTION_runas:
136 user_pwd = getpwnam(optarg);
137 if (user_pwd) {
138 user_uid = -1;
139 user_gid = -1;
140 } else if (!os_parse_runas_uid_gid(optarg)) {
141 error_report("User \"%s\" doesn't exist"
142 " (and is not <uid>:<gid>)",
143 optarg);
144 exit(1);
145 }
146 break;
147 case QEMU_OPTION_chroot:
148 chroot_dir = optarg;
149 break;
150 case QEMU_OPTION_daemonize:
151 daemonize = 1;
152 break;
153 default:
154 return -1;
155 }
156
157 return 0;
158 }
159
160 static void change_process_uid(void)
161 {
162 assert((user_uid == (uid_t)-1) || user_pwd == NULL);
163 assert((user_uid == (uid_t)-1) ==
164 (user_gid == (gid_t)-1));
165
166 if (user_pwd || user_uid != (uid_t)-1) {
167 gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid;
168 uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid;
169 if (setgid(intended_gid) < 0) {
170 error_report("Failed to setgid(%d)", intended_gid);
171 exit(1);
172 }
173 if (user_pwd) {
174 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
175 error_report("Failed to initgroups(\"%s\", %d)",
176 user_pwd->pw_name, user_pwd->pw_gid);
177 exit(1);
178 }
179 } else {
180 if (setgroups(1, &user_gid) < 0) {
181 error_report("Failed to setgroups(1, [%d])",
182 user_gid);
183 exit(1);
184 }
185 }
186 if (setuid(intended_uid) < 0) {
187 error_report("Failed to setuid(%d)", intended_uid);
188 exit(1);
189 }
190 if (setuid(0) != -1) {
191 error_report("Dropping privileges failed");
192 exit(1);
193 }
194 }
195 }
196
197 static void change_root(void)
198 {
199 if (chroot_dir) {
200 if (chroot(chroot_dir) < 0) {
201 error_report("chroot failed");
202 exit(1);
203 }
204 if (chdir("/")) {
205 error_report("not able to chdir to /: %s", strerror(errno));
206 exit(1);
207 }
208 }
209
210 }
211
212 void os_daemonize(void)
213 {
214 if (daemonize) {
215 pid_t pid;
216 int fds[2];
217
218 if (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) {
219 exit(1);
220 }
221
222 pid = fork();
223 if (pid > 0) {
224 uint8_t status;
225 ssize_t len;
226
227 close(fds[1]);
228
229 do {
230 len = read(fds[0], &status, 1);
231 } while (len < 0 && errno == EINTR);
232
233 /* only exit successfully if our child actually wrote
234 * a one-byte zero to our pipe, upon successful init */
235 exit(len == 1 && status == 0 ? 0 : 1);
236
237 } else if (pid < 0) {
238 exit(1);
239 }
240
241 close(fds[0]);
242 daemon_pipe = fds[1];
243
244 setsid();
245
246 pid = fork();
247 if (pid > 0) {
248 exit(0);
249 } else if (pid < 0) {
250 exit(1);
251 }
252 umask(027);
253
254 signal(SIGTSTP, SIG_IGN);
255 signal(SIGTTOU, SIG_IGN);
256 signal(SIGTTIN, SIG_IGN);
257 }
258 }
259
260 void os_setup_post(void)
261 {
262 int fd = 0;
263
264 if (daemonize) {
265 if (chdir("/")) {
266 error_report("not able to chdir to /: %s", strerror(errno));
267 exit(1);
268 }
269 TFR(fd = qemu_open_old("/dev/null", O_RDWR));
270 if (fd == -1) {
271 exit(1);
272 }
273 }
274
275 change_root();
276 change_process_uid();
277
278 if (daemonize) {
279 uint8_t status = 0;
280 ssize_t len;
281
282 dup2(fd, 0);
283 dup2(fd, 1);
284 /* In case -D is given do not redirect stderr to /dev/null */
285 if (!qemu_log_enabled()) {
286 dup2(fd, 2);
287 }
288
289 close(fd);
290
291 do {
292 len = write(daemon_pipe, &status, 1);
293 } while (len < 0 && errno == EINTR);
294 if (len != 1) {
295 exit(1);
296 }
297 }
298 }
299
300 void os_set_line_buffering(void)
301 {
302 setvbuf(stdout, NULL, _IOLBF, 0);
303 }
304
305 bool is_daemonized(void)
306 {
307 return daemonize;
308 }
309
310 int os_set_daemonize(bool d)
311 {
312 daemonize = d;
313 return 0;
314 }
315
316 int os_mlock(void)
317 {
318 #ifdef HAVE_MLOCKALL
319 int ret = 0;
320
321 ret = mlockall(MCL_CURRENT | MCL_FUTURE);
322 if (ret < 0) {
323 error_report("mlockall: %s", strerror(errno));
324 }
325
326 return ret;
327 #else
328 return -ENOSYS;
329 #endif
330 }