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