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 <unistd.h>
27 #include <fcntl.h>
28 #include <signal.h>
29 #include <sys/types.h>
30 #include <sys/wait.h>
31 /*needed for MAP_POPULATE before including qemu-options.h */
32 #include <sys/mman.h>
33 #include <pwd.h>
34 #include <libgen.h>
35
36 /* Needed early for CONFIG_BSD etc. */
37 #include "config-host.h"
38 #include "sysemu.h"
39 #include "net.h"
40 #include "qemu-options.h"
41
42 #ifdef CONFIG_LINUX
43 #include <sys/prctl.h>
44 #include <sys/syscall.h>
45 #endif
46
47 #ifdef CONFIG_EVENTFD
48 #include <sys/eventfd.h>
49 #endif
50
51 static struct passwd *user_pwd;
52 static const char *chroot_dir;
53 static int daemonize;
54 static int fds[2];
55
os_setup_early_signal_handling(void)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
termsig_handler(int signal)65 static void termsig_handler(int signal)
66 {
67 qemu_system_shutdown_request();
68 }
69
sigchld_handler(int signal)70 static void sigchld_handler(int signal)
71 {
72 waitpid(-1, NULL, WNOHANG);
73 }
74
os_setup_signal_handling(void)75 void os_setup_signal_handling(void)
76 {
77 struct sigaction act;
78
79 memset(&act, 0, sizeof(act));
80 act.sa_handler = termsig_handler;
81 sigaction(SIGINT, &act, NULL);
82 sigaction(SIGHUP, &act, NULL);
83 sigaction(SIGTERM, &act, NULL);
84
85 act.sa_handler = sigchld_handler;
86 act.sa_flags = SA_NOCLDSTOP;
87 sigaction(SIGCHLD, &act, NULL);
88 }
89
90 /* Find a likely location for support files using the location of the binary.
91 For installed binaries this will be "$bindir/../share/qemu". When
92 running from the build tree this will be "$bindir/../pc-bios". */
93 #define SHARE_SUFFIX "/share/qemu"
94 #define BUILD_SUFFIX "/pc-bios"
os_find_datadir(const char * argv0)95 char *os_find_datadir(const char *argv0)
96 {
97 char *dir;
98 char *p = NULL;
99 char *res;
100 char buf[PATH_MAX];
101 size_t max_len;
102
103 #if defined(__linux__)
104 {
105 int len;
106 len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
107 if (len > 0) {
108 buf[len] = 0;
109 p = buf;
110 }
111 }
112 #elif defined(__FreeBSD__)
113 {
114 static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
115 size_t len = sizeof(buf) - 1;
116
117 *buf = '\0';
118 if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
119 *buf) {
120 buf[sizeof(buf) - 1] = '\0';
121 p = buf;
122 }
123 }
124 #endif
125 /* If we don't have any way of figuring out the actual executable
126 location then try argv[0]. */
127 if (!p) {
128 p = realpath(argv0, buf);
129 if (!p) {
130 return NULL;
131 }
132 }
133 dir = dirname(p);
134 dir = dirname(dir);
135
136 max_len = strlen(dir) +
137 MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1;
138 res = qemu_mallocz(max_len);
139 snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX);
140 if (access(res, R_OK)) {
141 snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX);
142 if (access(res, R_OK)) {
143 qemu_free(res);
144 res = NULL;
145 }
146 }
147
148 return res;
149 }
150 #undef SHARE_SUFFIX
151 #undef BUILD_SUFFIX
152
os_set_proc_name(const char * s)153 void os_set_proc_name(const char *s)
154 {
155 #if defined(PR_SET_NAME)
156 char name[16];
157 if (!s)
158 return;
159 name[sizeof(name) - 1] = 0;
160 strncpy(name, s, sizeof(name));
161 /* Could rewrite argv[0] too, but that's a bit more complicated.
162 This simple way is enough for `top'. */
163 if (prctl(PR_SET_NAME, name)) {
164 perror("unable to change process name");
165 exit(1);
166 }
167 #else
168 fprintf(stderr, "Change of process name not supported by your OS\n");
169 exit(1);
170 #endif
171 }
172
173 /*
174 * Parse OS specific command line options.
175 * return 0 if option handled, -1 otherwise
176 */
os_parse_cmd_args(int index,const char * optarg)177 void os_parse_cmd_args(int index, const char *optarg)
178 {
179 switch (index) {
180 #ifdef CONFIG_SLIRP
181 case QEMU_OPTION_smb:
182 #if 1
183 net_slirp_smb(optarg);
184 #else
185 if (net_slirp_smb(optarg) < 0)
186 exit(1);
187 #endif
188 break;
189 #endif
190 case QEMU_OPTION_runas:
191 user_pwd = getpwnam(optarg);
192 if (!user_pwd) {
193 fprintf(stderr, "User \"%s\" doesn't exist\n", optarg);
194 exit(1);
195 }
196 break;
197 case QEMU_OPTION_chroot:
198 chroot_dir = optarg;
199 break;
200 case QEMU_OPTION_daemonize:
201 daemonize = 1;
202 break;
203 }
204 return;
205 }
206
change_process_uid(void)207 static void change_process_uid(void)
208 {
209 if (user_pwd) {
210 if (setgid(user_pwd->pw_gid) < 0) {
211 fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid);
212 exit(1);
213 }
214 if (setuid(user_pwd->pw_uid) < 0) {
215 fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid);
216 exit(1);
217 }
218 if (setuid(0) != -1) {
219 fprintf(stderr, "Dropping privileges failed\n");
220 exit(1);
221 }
222 }
223 }
224
change_root(void)225 static void change_root(void)
226 {
227 if (chroot_dir) {
228 if (chroot(chroot_dir) < 0) {
229 fprintf(stderr, "chroot failed\n");
230 exit(1);
231 }
232 if (chdir("/")) {
233 perror("not able to chdir to /");
234 exit(1);
235 }
236 }
237
238 }
239
os_daemonize(void)240 void os_daemonize(void)
241 {
242 if (daemonize) {
243 pid_t pid;
244
245 if (pipe(fds) == -1)
246 exit(1);
247
248 pid = fork();
249 if (pid > 0) {
250 uint8_t status;
251 ssize_t len;
252
253 close(fds[1]);
254
255 again:
256 len = read(fds[0], &status, 1);
257 if (len == -1 && (errno == EINTR))
258 goto again;
259
260 if (len != 1)
261 exit(1);
262 else if (status == 1) {
263 fprintf(stderr, "Could not acquire pidfile: %s\n", strerror(errno));
264 exit(1);
265 } else
266 exit(0);
267 } else if (pid < 0)
268 exit(1);
269
270 close(fds[0]);
271 qemu_set_cloexec(fds[1]);
272
273 setsid();
274
275 pid = fork();
276 if (pid > 0)
277 exit(0);
278 else if (pid < 0)
279 exit(1);
280
281 umask(027);
282
283 signal(SIGTSTP, SIG_IGN);
284 signal(SIGTTOU, SIG_IGN);
285 signal(SIGTTIN, SIG_IGN);
286 }
287 }
288
os_setup_post(void)289 void os_setup_post(void)
290 {
291 int fd = 0;
292
293 if (daemonize) {
294 uint8_t status = 0;
295 ssize_t len;
296
297 again1:
298 len = write(fds[1], &status, 1);
299 if (len == -1 && (errno == EINTR))
300 goto again1;
301
302 if (len != 1)
303 exit(1);
304
305 if (chdir("/")) {
306 perror("not able to chdir to /");
307 exit(1);
308 }
309 TFR(fd = qemu_open("/dev/null", O_RDWR));
310 if (fd == -1)
311 exit(1);
312 }
313
314 change_root();
315 change_process_uid();
316
317 if (daemonize) {
318 dup2(fd, 0);
319 dup2(fd, 1);
320 dup2(fd, 2);
321
322 close(fd);
323 }
324 }
325
os_pidfile_error(void)326 void os_pidfile_error(void)
327 {
328 if (daemonize) {
329 uint8_t status = 1;
330 if (write(fds[1], &status, 1) != 1) {
331 perror("daemonize. Writing to pipe\n");
332 }
333 } else
334 fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno));
335 }
336
os_set_line_buffering(void)337 void os_set_line_buffering(void)
338 {
339 setvbuf(stdout, NULL, _IOLBF, 0);
340 }
341
342 /*
343 * Creates an eventfd that looks like a pipe and has EFD_CLOEXEC set.
344 */
qemu_eventfd(int fds[2])345 int qemu_eventfd(int fds[2])
346 {
347 #ifdef CONFIG_EVENTFD
348 int ret;
349
350 ret = eventfd(0, 0);
351 if (ret >= 0) {
352 fds[0] = ret;
353 qemu_set_cloexec(ret);
354 if ((fds[1] = dup(ret)) == -1) {
355 close(ret);
356 return -1;
357 }
358 qemu_set_cloexec(fds[1]);
359 return 0;
360 }
361
362 if (errno != ENOSYS) {
363 return -1;
364 }
365 #endif
366
367 return qemu_pipe(fds);
368 }
369
qemu_create_pidfile(const char * filename)370 int qemu_create_pidfile(const char *filename)
371 {
372 char buffer[128];
373 int len;
374 int fd;
375
376 fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
377 if (fd == -1) {
378 return -1;
379 }
380 if (lockf(fd, F_TLOCK, 0) == -1) {
381 return -1;
382 }
383 len = snprintf(buffer, sizeof(buffer), "%ld\n", (long)getpid());
384 if (write(fd, buffer, len) != len) {
385 return -1;
386 }
387
388 return 0;
389 }
390
qemu_get_thread_id(void)391 int qemu_get_thread_id(void)
392 {
393 #if defined (__linux__)
394 return syscall(SYS_gettid);
395 #else
396 return getpid();
397 #endif
398 }
399