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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 | #include "qemu/error-report.h" | |
33 | #include "qemu/log.h" | |
34 | #include "sysemu/runstate.h" | |
35 | #include "qemu/cutils.h" | |
36 | ||
37 | #ifdef CONFIG_LINUX | |
38 | #include <sys/prctl.h> | |
39 | #endif | |
40 | ||
41 | ||
42 | void os_setup_early_signal_handling(void) | |
43 | { | |
44 | struct sigaction act; | |
45 | sigfillset(&act.sa_mask); | |
46 | act.sa_flags = 0; | |
47 | act.sa_handler = SIG_IGN; | |
48 | sigaction(SIGPIPE, &act, NULL); | |
49 | } | |
50 | ||
51 | static void termsig_handler(int signal, siginfo_t *info, void *c) | |
52 | { | |
53 | qemu_system_killed(info->si_signo, info->si_pid); | |
54 | } | |
55 | ||
56 | void os_setup_signal_handling(void) | |
57 | { | |
58 | struct sigaction act; | |
59 | ||
60 | memset(&act, 0, sizeof(act)); | |
61 | act.sa_sigaction = termsig_handler; | |
62 | act.sa_flags = SA_SIGINFO; | |
63 | sigaction(SIGINT, &act, NULL); | |
64 | sigaction(SIGHUP, &act, NULL); | |
65 | sigaction(SIGTERM, &act, NULL); | |
66 | } | |
67 | ||
68 | void os_set_proc_name(const char *s) | |
69 | { | |
70 | #if defined(PR_SET_NAME) | |
71 | char name[16]; | |
72 | if (!s) | |
73 | return; | |
74 | pstrcpy(name, sizeof(name), s); | |
75 | /* Could rewrite argv[0] too, but that's a bit more complicated. | |
76 | This simple way is enough for `top'. */ | |
77 | if (prctl(PR_SET_NAME, name)) { | |
78 | error_report("unable to change process name: %s", strerror(errno)); | |
79 | exit(1); | |
80 | } | |
81 | #else | |
82 | error_report("Change of process name not supported by your OS"); | |
83 | exit(1); | |
84 | #endif | |
85 | } | |
86 | ||
87 | ||
88 | /* | |
89 | * Must set all three of these at once. | |
90 | * Legal combinations are unset by name by uid | |
91 | */ | |
92 | static struct passwd *user_pwd; /* NULL non-NULL NULL */ | |
93 | static uid_t user_uid = (uid_t)-1; /* -1 -1 >=0 */ | |
94 | static gid_t user_gid = (gid_t)-1; /* -1 -1 >=0 */ | |
95 | ||
96 | /* | |
97 | * Prepare to change user ID. user_id can be one of 3 forms: | |
98 | * - a username, in which case user ID will be changed to its uid, | |
99 | * with primary and supplementary groups set up too; | |
100 | * - a numeric uid, in which case only the uid will be set; | |
101 | * - a pair of numeric uid:gid. | |
102 | */ | |
103 | bool os_set_runas(const char *user_id) | |
104 | { | |
105 | unsigned long lv; | |
106 | const char *ep; | |
107 | uid_t got_uid; | |
108 | gid_t got_gid; | |
109 | int rc; | |
110 | ||
111 | user_pwd = getpwnam(user_id); | |
112 | if (user_pwd) { | |
113 | user_uid = -1; | |
114 | user_gid = -1; | |
115 | return true; | |
116 | } | |
117 | ||
118 | rc = qemu_strtoul(user_id, &ep, 0, &lv); | |
119 | got_uid = lv; /* overflow here is ID in C99 */ | |
120 | if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) { | |
121 | return false; | |
122 | } | |
123 | ||
124 | rc = qemu_strtoul(ep + 1, 0, 0, &lv); | |
125 | got_gid = lv; /* overflow here is ID in C99 */ | |
126 | if (rc || got_gid != lv || got_gid == (gid_t)-1) { | |
127 | return false; | |
128 | } | |
129 | ||
130 | user_pwd = NULL; | |
131 | user_uid = got_uid; | |
132 | user_gid = got_gid; | |
133 | return true; | |
134 | } | |
135 | ||
136 | static void change_process_uid(void) | |
137 | { | |
138 | assert((user_uid == (uid_t)-1) || user_pwd == NULL); | |
139 | assert((user_uid == (uid_t)-1) == | |
140 | (user_gid == (gid_t)-1)); | |
141 | ||
142 | if (user_pwd || user_uid != (uid_t)-1) { | |
143 | gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid; | |
144 | uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid; | |
145 | if (setgid(intended_gid) < 0) { | |
146 | error_report("Failed to setgid(%d)", intended_gid); | |
147 | exit(1); | |
148 | } | |
149 | if (user_pwd) { | |
150 | if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { | |
151 | error_report("Failed to initgroups(\"%s\", %d)", | |
152 | user_pwd->pw_name, user_pwd->pw_gid); | |
153 | exit(1); | |
154 | } | |
155 | } else { | |
156 | if (setgroups(1, &user_gid) < 0) { | |
157 | error_report("Failed to setgroups(1, [%d])", | |
158 | user_gid); | |
159 | exit(1); | |
160 | } | |
161 | } | |
162 | if (setuid(intended_uid) < 0) { | |
163 | error_report("Failed to setuid(%d)", intended_uid); | |
164 | exit(1); | |
165 | } | |
166 | if (setuid(0) != -1) { | |
167 | error_report("Dropping privileges failed"); | |
168 | exit(1); | |
169 | } | |
170 | } | |
171 | } | |
172 | ||
173 | ||
174 | static const char *chroot_dir; | |
175 | ||
176 | void os_set_chroot(const char *path) | |
177 | { | |
178 | chroot_dir = path; | |
179 | } | |
180 | ||
181 | static void change_root(void) | |
182 | { | |
183 | if (chroot_dir) { | |
184 | if (chroot(chroot_dir) < 0) { | |
185 | error_report("chroot failed"); | |
186 | exit(1); | |
187 | } | |
188 | if (chdir("/")) { | |
189 | error_report("not able to chdir to /: %s", strerror(errno)); | |
190 | exit(1); | |
191 | } | |
192 | } | |
193 | ||
194 | } | |
195 | ||
196 | ||
197 | static int daemonize; | |
198 | static int daemon_pipe; | |
199 | ||
200 | bool is_daemonized(void) | |
201 | { | |
202 | return daemonize; | |
203 | } | |
204 | ||
205 | int os_set_daemonize(bool d) | |
206 | { | |
207 | daemonize = d; | |
208 | return 0; | |
209 | } | |
210 | ||
211 | void os_daemonize(void) | |
212 | { | |
213 | if (daemonize) { | |
214 | pid_t pid; | |
215 | int fds[2]; | |
216 | ||
217 | if (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) { | |
218 | exit(1); | |
219 | } | |
220 | ||
221 | pid = fork(); | |
222 | if (pid > 0) { | |
223 | uint8_t status; | |
224 | ssize_t len; | |
225 | ||
226 | close(fds[1]); | |
227 | ||
228 | do { | |
229 | len = read(fds[0], &status, 1); | |
230 | } while (len < 0 && errno == EINTR); | |
231 | ||
232 | /* only exit successfully if our child actually wrote | |
233 | * a one-byte zero to our pipe, upon successful init */ | |
234 | exit(len == 1 && status == 0 ? 0 : 1); | |
235 | ||
236 | } else if (pid < 0) { | |
237 | exit(1); | |
238 | } | |
239 | ||
240 | close(fds[0]); | |
241 | daemon_pipe = fds[1]; | |
242 | ||
243 | setsid(); | |
244 | ||
245 | pid = fork(); | |
246 | if (pid > 0) { | |
247 | exit(0); | |
248 | } else if (pid < 0) { | |
249 | exit(1); | |
250 | } | |
251 | umask(027); | |
252 | ||
253 | signal(SIGTSTP, SIG_IGN); | |
254 | signal(SIGTTOU, SIG_IGN); | |
255 | signal(SIGTTIN, SIG_IGN); | |
256 | } | |
257 | } | |
258 | ||
259 | void os_setup_post(void) | |
260 | { | |
261 | int fd = 0; | |
262 | ||
263 | if (daemonize) { | |
264 | if (chdir("/")) { | |
265 | error_report("not able to chdir to /: %s", strerror(errno)); | |
266 | exit(1); | |
267 | } | |
268 | fd = RETRY_ON_EINTR(qemu_open_old("/dev/null", O_RDWR)); | |
269 | if (fd == -1) { | |
270 | exit(1); | |
271 | } | |
272 | } | |
273 | ||
274 | change_root(); | |
275 | change_process_uid(); | |
276 | ||
277 | if (daemonize) { | |
278 | uint8_t status = 0; | |
279 | ssize_t len; | |
280 | ||
281 | dup2(fd, 0); | |
282 | dup2(fd, 1); | |
283 | /* In case -D is given do not redirect stderr to /dev/null */ | |
284 | if (!qemu_log_enabled()) { | |
285 | dup2(fd, 2); | |
286 | } | |
287 | ||
288 | close(fd); | |
289 | ||
290 | do { | |
291 | len = write(daemon_pipe, &status, 1); | |
292 | } while (len < 0 && errno == EINTR); | |
293 | if (len != 1) { | |
294 | exit(1); | |
295 | } | |
296 | } | |
297 | } | |
298 | ||
299 | void os_set_line_buffering(void) | |
300 | { | |
301 | setvbuf(stdout, NULL, _IOLBF, 0); | |
302 | } | |
303 | ||
304 | int os_mlock(void) | |
305 | { | |
306 | #ifdef HAVE_MLOCKALL | |
307 | int ret = 0; | |
308 | ||
309 | ret = mlockall(MCL_CURRENT | MCL_FUTURE); | |
310 | if (ret < 0) { | |
311 | error_report("mlockall: %s", strerror(errno)); | |
312 | } | |
313 | ||
314 | return ret; | |
315 | #else | |
316 | return -ENOSYS; | |
317 | #endif | |
318 | } |