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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
d38ea87a 26#include "qemu/osdep.h"
8d963e6a 27#include <sys/wait.h>
8847cfe8 28#include <pwd.h>
cc4662f9 29#include <grp.h>
6170540b 30#include <libgen.h>
86b645e7 31
a8d25326 32#include "qemu-common.h"
86b645e7 33/* Needed early for CONFIG_BSD etc. */
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34#include "net/slirp.h"
35#include "qemu-options.h"
f853ac66 36#include "qemu/error-report.h"
96c33a45 37#include "qemu/log.h"
54d31236 38#include "sysemu/runstate.h"
f348b6d1 39#include "qemu/cutils.h"
86b645e7 40
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41#ifdef CONFIG_LINUX
42#include <sys/prctl.h>
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43#endif
44
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45/*
46 * Must set all three of these at once.
47 * Legal combinations are unset by name by uid
48 */
49static struct passwd *user_pwd; /* NULL non-NULL NULL */
50static uid_t user_uid = (uid_t)-1; /* -1 -1 >=0 */
51static gid_t user_gid = (gid_t)-1; /* -1 -1 >=0 */
52
0766379d 53static const char *chroot_dir;
eb505be1 54static int daemonize;
0be5e436 55static int daemon_pipe;
8847cfe8 56
fe98ac14 57void os_setup_early_signal_handling(void)
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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}
8d963e6a 65
f64622c4 66static void termsig_handler(int signal, siginfo_t *info, void *c)
8d963e6a 67{
f64622c4 68 qemu_system_killed(info->si_signo, info->si_pid);
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69}
70
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71void os_setup_signal_handling(void)
72{
73 struct sigaction act;
74
75 memset(&act, 0, sizeof(act));
f64622c4
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76 act.sa_sigaction = termsig_handler;
77 act.sa_flags = SA_SIGINFO;
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78 sigaction(SIGINT, &act, NULL);
79 sigaction(SIGHUP, &act, NULL);
80 sigaction(SIGTERM, &act, NULL);
8d963e6a 81}
6170540b 82
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83void os_set_proc_name(const char *s)
84{
85#if defined(PR_SET_NAME)
86 char name[16];
87 if (!s)
88 return;
3eadc68e 89 pstrcpy(name, sizeof(name), s);
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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)) {
a7aaec14 93 error_report("unable to change process name: %s", strerror(errno));
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94 exit(1);
95 }
96#else
22cd4f48 97 error_report("Change of process name not supported by your OS");
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98 exit(1);
99#endif
100}
101
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102
103static 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
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129/*
130 * Parse OS specific command line options.
131 * return 0 if option handled, -1 otherwise
132 */
1217d6ca 133int os_parse_cmd_args(int index, const char *optarg)
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134{
135 switch (index) {
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136 case QEMU_OPTION_runas:
137 user_pwd = getpwnam(optarg);
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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);
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145 exit(1);
146 }
147 break;
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148 case QEMU_OPTION_chroot:
149 chroot_dir = optarg;
150 break;
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151 case QEMU_OPTION_daemonize:
152 daemonize = 1;
153 break;
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154#if defined(CONFIG_LINUX)
155 case QEMU_OPTION_enablefips:
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156 warn_report("-enable-fips is deprecated, please build QEMU with "
157 "the `libgcrypt` library as the cryptography provider "
158 "to enable FIPS compliance");
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159 fips_set_state(true);
160 break;
161#endif
1217d6ca
TH
162 default:
163 return -1;
59a5264b 164 }
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165
166 return 0;
59a5264b 167}
8847cfe8 168
e06eb601 169static void change_process_uid(void)
8847cfe8 170{
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171 assert((user_uid == (uid_t)-1) || user_pwd == NULL);
172 assert((user_uid == (uid_t)-1) ==
173 (user_gid == (gid_t)-1));
174
175 if (user_pwd || user_uid != (uid_t)-1) {
176 gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid;
177 uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid;
178 if (setgid(intended_gid) < 0) {
179 error_report("Failed to setgid(%d)", intended_gid);
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180 exit(1);
181 }
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182 if (user_pwd) {
183 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
184 error_report("Failed to initgroups(\"%s\", %d)",
185 user_pwd->pw_name, user_pwd->pw_gid);
186 exit(1);
187 }
188 } else {
189 if (setgroups(1, &user_gid) < 0) {
190 error_report("Failed to setgroups(1, [%d])",
191 user_gid);
192 exit(1);
193 }
cc4662f9 194 }
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195 if (setuid(intended_uid) < 0) {
196 error_report("Failed to setuid(%d)", intended_uid);
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197 exit(1);
198 }
199 if (setuid(0) != -1) {
f0a2171b 200 error_report("Dropping privileges failed");
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201 exit(1);
202 }
203 }
204}
0766379d 205
e06eb601 206static void change_root(void)
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207{
208 if (chroot_dir) {
209 if (chroot(chroot_dir) < 0) {
22cd4f48 210 error_report("chroot failed");
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211 exit(1);
212 }
213 if (chdir("/")) {
a7aaec14 214 error_report("not able to chdir to /: %s", strerror(errno));
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215 exit(1);
216 }
217 }
218
219}
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220
221void os_daemonize(void)
222{
223 if (daemonize) {
63ce8e15 224 pid_t pid;
0be5e436 225 int fds[2];
eb505be1 226
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227 if (pipe(fds) == -1) {
228 exit(1);
229 }
eb505be1 230
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231 pid = fork();
232 if (pid > 0) {
233 uint8_t status;
234 ssize_t len;
eb505be1 235
63ce8e15 236 close(fds[1]);
eb505be1 237
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238 do {
239 len = read(fds[0], &status, 1);
240 } while (len < 0 && errno == EINTR);
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241
242 /* only exit successfully if our child actually wrote
243 * a one-byte zero to our pipe, upon successful init */
244 exit(len == 1 && status == 0 ? 0 : 1);
245
246 } else if (pid < 0) {
247 exit(1);
248 }
eb505be1 249
63ce8e15 250 close(fds[0]);
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251 daemon_pipe = fds[1];
252 qemu_set_cloexec(daemon_pipe);
eb505be1 253
63ce8e15 254 setsid();
eb505be1 255
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256 pid = fork();
257 if (pid > 0) {
258 exit(0);
259 } else if (pid < 0) {
260 exit(1);
261 }
262 umask(027);
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263
264 signal(SIGTSTP, SIG_IGN);
265 signal(SIGTTOU, SIG_IGN);
266 signal(SIGTTIN, SIG_IGN);
267 }
268}
269
270void os_setup_post(void)
271{
272 int fd = 0;
273
274 if (daemonize) {
eb505be1 275 if (chdir("/")) {
a7aaec14 276 error_report("not able to chdir to /: %s", strerror(errno));
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277 exit(1);
278 }
448058aa 279 TFR(fd = qemu_open_old("/dev/null", O_RDWR));
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280 if (fd == -1) {
281 exit(1);
282 }
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283 }
284
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285 change_root();
286 change_process_uid();
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287
288 if (daemonize) {
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289 uint8_t status = 0;
290 ssize_t len;
291
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292 dup2(fd, 0);
293 dup2(fd, 1);
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294 /* In case -D is given do not redirect stderr to /dev/null */
295 if (!qemu_logfile) {
296 dup2(fd, 2);
297 }
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298
299 close(fd);
25cec2b8
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300
301 do {
302 len = write(daemon_pipe, &status, 1);
303 } while (len < 0 && errno == EINTR);
304 if (len != 1) {
305 exit(1);
306 }
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307 }
308}
309
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310void os_set_line_buffering(void)
311{
312 setvbuf(stdout, NULL, _IOLBF, 0);
313}
949d31e6 314
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315bool is_daemonized(void)
316{
317 return daemonize;
318}
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319
320int os_mlock(void)
321{
195588cc 322#ifdef HAVE_MLOCKALL
888a6bc6
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323 int ret = 0;
324
325 ret = mlockall(MCL_CURRENT | MCL_FUTURE);
326 if (ret < 0) {
a7aaec14 327 error_report("mlockall: %s", strerror(errno));
888a6bc6
SM
328 }
329
330 return ret;
195588cc
DC
331#else
332 return -ENOSYS;
333#endif
888a6bc6 334}