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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 "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 | } |