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-common.h" |
33 | /* Needed early for CONFIG_BSD etc. */ |
34 | #include "net/slirp.h" |
35 | #include "qemu-options.h" |
36 | #include "qemu/error-report.h" |
37 | #include "qemu/log.h" |
38 | #include "sysemu/runstate.h" |
39 | #include "qemu/cutils.h" |
40 | |
41 | #ifdef CONFIG_LINUX |
42 | #include <sys/prctl.h> |
43 | #endif |
44 | |
45 | /* |
46 | * Must set all three of these at once. |
47 | * Legal combinations are unset by name by uid |
48 | */ |
49 | static struct passwd *user_pwd; /* NULL non-NULL NULL */ |
50 | static uid_t user_uid = (uid_t)-1; /* -1 -1 >=0 */ |
51 | static gid_t user_gid = (gid_t)-1; /* -1 -1 >=0 */ |
52 | |
53 | static const char *chroot_dir; |
54 | static int daemonize; |
55 | static int daemon_pipe; |
56 | |
57 | void os_setup_early_signal_handling(void) |
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 | } |
65 | |
66 | static void termsig_handler(int signal, siginfo_t *info, void *c) |
67 | { |
68 | qemu_system_killed(info->si_signo, info->si_pid); |
69 | } |
70 | |
71 | void os_setup_signal_handling(void) |
72 | { |
73 | struct sigaction act; |
74 | |
75 | memset(&act, 0, sizeof(act)); |
76 | act.sa_sigaction = termsig_handler; |
77 | act.sa_flags = SA_SIGINFO; |
78 | sigaction(SIGINT, &act, NULL); |
79 | sigaction(SIGHUP, &act, NULL); |
80 | sigaction(SIGTERM, &act, NULL); |
81 | } |
82 | |
83 | /* Find a likely location for support files using the location of the binary. |
84 | For installed binaries this will be "$bindir/../share/qemu". When |
85 | running from the build tree this will be "$bindir/../pc-bios". */ |
86 | #define SHARE_SUFFIX "/share/qemu" |
87 | #define BUILD_SUFFIX "/pc-bios" |
88 | char *os_find_datadir(void) |
89 | { |
90 | char *dir, *exec_dir; |
91 | char *res; |
92 | size_t max_len; |
93 | |
94 | exec_dir = qemu_get_exec_dir(); |
95 | if (exec_dir == NULL) { |
96 | return NULL; |
97 | } |
98 | dir = g_path_get_dirname(exec_dir); |
99 | |
100 | max_len = strlen(dir) + |
101 | MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1; |
102 | res = g_malloc0(max_len); |
103 | snprintf(res, max_len, "%s%s" , dir, SHARE_SUFFIX); |
104 | if (access(res, R_OK)) { |
105 | snprintf(res, max_len, "%s%s" , dir, BUILD_SUFFIX); |
106 | if (access(res, R_OK)) { |
107 | g_free(res); |
108 | res = NULL; |
109 | } |
110 | } |
111 | |
112 | g_free(dir); |
113 | g_free(exec_dir); |
114 | return res; |
115 | } |
116 | #undef SHARE_SUFFIX |
117 | #undef BUILD_SUFFIX |
118 | |
119 | void os_set_proc_name(const char *s) |
120 | { |
121 | #if defined(PR_SET_NAME) |
122 | char name[16]; |
123 | if (!s) |
124 | return; |
125 | pstrcpy(name, sizeof(name), s); |
126 | /* Could rewrite argv[0] too, but that's a bit more complicated. |
127 | This simple way is enough for `top'. */ |
128 | if (prctl(PR_SET_NAME, name)) { |
129 | error_report("unable to change process name: %s" , strerror(errno)); |
130 | exit(1); |
131 | } |
132 | #else |
133 | error_report("Change of process name not supported by your OS" ); |
134 | exit(1); |
135 | #endif |
136 | } |
137 | |
138 | |
139 | static bool os_parse_runas_uid_gid(const char *optarg) |
140 | { |
141 | unsigned long lv; |
142 | const char *ep; |
143 | uid_t got_uid; |
144 | gid_t got_gid; |
145 | int rc; |
146 | |
147 | rc = qemu_strtoul(optarg, &ep, 0, &lv); |
148 | got_uid = lv; /* overflow here is ID in C99 */ |
149 | if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) { |
150 | return false; |
151 | } |
152 | |
153 | rc = qemu_strtoul(ep + 1, 0, 0, &lv); |
154 | got_gid = lv; /* overflow here is ID in C99 */ |
155 | if (rc || got_gid != lv || got_gid == (gid_t)-1) { |
156 | return false; |
157 | } |
158 | |
159 | user_pwd = NULL; |
160 | user_uid = got_uid; |
161 | user_gid = got_gid; |
162 | return true; |
163 | } |
164 | |
165 | /* |
166 | * Parse OS specific command line options. |
167 | * return 0 if option handled, -1 otherwise |
168 | */ |
169 | int os_parse_cmd_args(int index, const char *optarg) |
170 | { |
171 | switch (index) { |
172 | case QEMU_OPTION_runas: |
173 | user_pwd = getpwnam(optarg); |
174 | if (user_pwd) { |
175 | user_uid = -1; |
176 | user_gid = -1; |
177 | } else if (!os_parse_runas_uid_gid(optarg)) { |
178 | error_report("User \"%s\" doesn't exist" |
179 | " (and is not <uid>:<gid>)" , |
180 | optarg); |
181 | exit(1); |
182 | } |
183 | break; |
184 | case QEMU_OPTION_chroot: |
185 | chroot_dir = optarg; |
186 | break; |
187 | case QEMU_OPTION_daemonize: |
188 | daemonize = 1; |
189 | break; |
190 | #if defined(CONFIG_LINUX) |
191 | case QEMU_OPTION_enablefips: |
192 | fips_set_state(true); |
193 | break; |
194 | #endif |
195 | default: |
196 | return -1; |
197 | } |
198 | |
199 | return 0; |
200 | } |
201 | |
202 | static void change_process_uid(void) |
203 | { |
204 | assert((user_uid == (uid_t)-1) || user_pwd == NULL); |
205 | assert((user_uid == (uid_t)-1) == |
206 | (user_gid == (gid_t)-1)); |
207 | |
208 | if (user_pwd || user_uid != (uid_t)-1) { |
209 | gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid; |
210 | uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid; |
211 | if (setgid(intended_gid) < 0) { |
212 | error_report("Failed to setgid(%d)" , intended_gid); |
213 | exit(1); |
214 | } |
215 | if (user_pwd) { |
216 | if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { |
217 | error_report("Failed to initgroups(\"%s\", %d)" , |
218 | user_pwd->pw_name, user_pwd->pw_gid); |
219 | exit(1); |
220 | } |
221 | } else { |
222 | if (setgroups(1, &user_gid) < 0) { |
223 | error_report("Failed to setgroups(1, [%d])" , |
224 | user_gid); |
225 | exit(1); |
226 | } |
227 | } |
228 | if (setuid(intended_uid) < 0) { |
229 | error_report("Failed to setuid(%d)" , intended_uid); |
230 | exit(1); |
231 | } |
232 | if (setuid(0) != -1) { |
233 | error_report("Dropping privileges failed" ); |
234 | exit(1); |
235 | } |
236 | } |
237 | } |
238 | |
239 | static void change_root(void) |
240 | { |
241 | if (chroot_dir) { |
242 | if (chroot(chroot_dir) < 0) { |
243 | error_report("chroot failed" ); |
244 | exit(1); |
245 | } |
246 | if (chdir("/" )) { |
247 | error_report("not able to chdir to /: %s" , strerror(errno)); |
248 | exit(1); |
249 | } |
250 | } |
251 | |
252 | } |
253 | |
254 | void os_daemonize(void) |
255 | { |
256 | if (daemonize) { |
257 | pid_t pid; |
258 | int fds[2]; |
259 | |
260 | if (pipe(fds) == -1) { |
261 | exit(1); |
262 | } |
263 | |
264 | pid = fork(); |
265 | if (pid > 0) { |
266 | uint8_t status; |
267 | ssize_t len; |
268 | |
269 | close(fds[1]); |
270 | |
271 | do { |
272 | len = read(fds[0], &status, 1); |
273 | } while (len < 0 && errno == EINTR); |
274 | |
275 | /* only exit successfully if our child actually wrote |
276 | * a one-byte zero to our pipe, upon successful init */ |
277 | exit(len == 1 && status == 0 ? 0 : 1); |
278 | |
279 | } else if (pid < 0) { |
280 | exit(1); |
281 | } |
282 | |
283 | close(fds[0]); |
284 | daemon_pipe = fds[1]; |
285 | qemu_set_cloexec(daemon_pipe); |
286 | |
287 | setsid(); |
288 | |
289 | pid = fork(); |
290 | if (pid > 0) { |
291 | exit(0); |
292 | } else if (pid < 0) { |
293 | exit(1); |
294 | } |
295 | umask(027); |
296 | |
297 | signal(SIGTSTP, SIG_IGN); |
298 | signal(SIGTTOU, SIG_IGN); |
299 | signal(SIGTTIN, SIG_IGN); |
300 | } |
301 | } |
302 | |
303 | void os_setup_post(void) |
304 | { |
305 | int fd = 0; |
306 | |
307 | if (daemonize) { |
308 | if (chdir("/" )) { |
309 | error_report("not able to chdir to /: %s" , strerror(errno)); |
310 | exit(1); |
311 | } |
312 | TFR(fd = qemu_open("/dev/null" , O_RDWR)); |
313 | if (fd == -1) { |
314 | exit(1); |
315 | } |
316 | } |
317 | |
318 | change_root(); |
319 | change_process_uid(); |
320 | |
321 | if (daemonize) { |
322 | uint8_t status = 0; |
323 | ssize_t len; |
324 | |
325 | dup2(fd, 0); |
326 | dup2(fd, 1); |
327 | /* In case -D is given do not redirect stderr to /dev/null */ |
328 | if (!qemu_logfile) { |
329 | dup2(fd, 2); |
330 | } |
331 | |
332 | close(fd); |
333 | |
334 | do { |
335 | len = write(daemon_pipe, &status, 1); |
336 | } while (len < 0 && errno == EINTR); |
337 | if (len != 1) { |
338 | exit(1); |
339 | } |
340 | } |
341 | } |
342 | |
343 | void os_set_line_buffering(void) |
344 | { |
345 | setvbuf(stdout, NULL, _IOLBF, 0); |
346 | } |
347 | |
348 | bool is_daemonized(void) |
349 | { |
350 | return daemonize; |
351 | } |
352 | |
353 | int os_mlock(void) |
354 | { |
355 | int ret = 0; |
356 | |
357 | ret = mlockall(MCL_CURRENT | MCL_FUTURE); |
358 | if (ret < 0) { |
359 | error_report("mlockall: %s" , strerror(errno)); |
360 | } |
361 | |
362 | return ret; |
363 | } |
364 | |