xref: /openbmc/qemu/os-posix.c (revision 2c9b15ca) 
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 <grp.h>
35 #include <libgen.h>
36 
37 /* Needed early for CONFIG_BSD etc. */
38 #include "config-host.h"
39 #include "sysemu/sysemu.h"
40 #include "net/slirp.h"
41 #include "qemu-options.h"
42 
43 #ifdef CONFIG_LINUX
44 #include <sys/prctl.h>
45 #endif
46 
47 #ifdef __FreeBSD__
48 #include <sys/sysctl.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 = g_malloc0(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             g_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     pstrcpy(name, sizeof(name), s);
152     /* Could rewrite argv[0] too, but that's a bit more complicated.
153        This simple way is enough for `top'. */
154     if (prctl(PR_SET_NAME, name)) {
155         perror("unable to change process name");
156         exit(1);
157     }
158 #else
159     fprintf(stderr, "Change of process name not supported by your OS\n");
160     exit(1);
161 #endif
162 }
163 
164 /*
165  * Parse OS specific command line options.
166  * return 0 if option handled, -1 otherwise
167  */
168 void os_parse_cmd_args(int index, const char *optarg)
169 {
170     switch (index) {
171 #ifdef CONFIG_SLIRP
172     case QEMU_OPTION_smb:
173         if (net_slirp_smb(optarg) < 0)
174             exit(1);
175         break;
176 #endif
177     case QEMU_OPTION_runas:
178         user_pwd = getpwnam(optarg);
179         if (!user_pwd) {
180             fprintf(stderr, "User \"%s\" doesn't exist\n", 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     }
196 }
197 
198 static void change_process_uid(void)
199 {
200     if (user_pwd) {
201         if (setgid(user_pwd->pw_gid) < 0) {
202             fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid);
203             exit(1);
204         }
205         if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
206             fprintf(stderr, "Failed to initgroups(\"%s\", %d)\n",
207                     user_pwd->pw_name, user_pwd->pw_gid);
208             exit(1);
209         }
210         if (setuid(user_pwd->pw_uid) < 0) {
211             fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid);
212             exit(1);
213         }
214         if (setuid(0) != -1) {
215             fprintf(stderr, "Dropping privileges failed\n");
216             exit(1);
217         }
218     }
219 }
220 
221 static void change_root(void)
222 {
223     if (chroot_dir) {
224         if (chroot(chroot_dir) < 0) {
225             fprintf(stderr, "chroot failed\n");
226             exit(1);
227         }
228         if (chdir("/")) {
229             perror("not able to chdir to /");
230             exit(1);
231         }
232     }
233 
234 }
235 
236 void os_daemonize(void)
237 {
238     if (daemonize) {
239 	pid_t pid;
240 
241 	if (pipe(fds) == -1)
242 	    exit(1);
243 
244 	pid = fork();
245 	if (pid > 0) {
246 	    uint8_t status;
247 	    ssize_t len;
248 
249 	    close(fds[1]);
250 
251 	again:
252             len = read(fds[0], &status, 1);
253             if (len == -1 && (errno == EINTR))
254                 goto again;
255 
256             if (len != 1)
257                 exit(1);
258             else if (status == 1) {
259                 fprintf(stderr, "Could not acquire pidfile: %s\n", strerror(errno));
260                 exit(1);
261             } else
262                 exit(0);
263 	} else if (pid < 0)
264             exit(1);
265 
266 	close(fds[0]);
267 	qemu_set_cloexec(fds[1]);
268 
269 	setsid();
270 
271 	pid = fork();
272 	if (pid > 0)
273 	    exit(0);
274 	else if (pid < 0)
275 	    exit(1);
276 
277 	umask(027);
278 
279         signal(SIGTSTP, SIG_IGN);
280         signal(SIGTTOU, SIG_IGN);
281         signal(SIGTTIN, SIG_IGN);
282     }
283 }
284 
285 void os_setup_post(void)
286 {
287     int fd = 0;
288 
289     if (daemonize) {
290 	uint8_t status = 0;
291 	ssize_t len;
292 
293     again1:
294 	len = write(fds[1], &status, 1);
295 	if (len == -1 && (errno == EINTR))
296 	    goto again1;
297 
298 	if (len != 1)
299 	    exit(1);
300 
301         if (chdir("/")) {
302             perror("not able to chdir to /");
303             exit(1);
304         }
305 	TFR(fd = qemu_open("/dev/null", O_RDWR));
306 	if (fd == -1)
307 	    exit(1);
308     }
309 
310     change_root();
311     change_process_uid();
312 
313     if (daemonize) {
314         dup2(fd, 0);
315         dup2(fd, 1);
316         dup2(fd, 2);
317 
318         close(fd);
319     }
320 }
321 
322 void os_pidfile_error(void)
323 {
324     if (daemonize) {
325         uint8_t status = 1;
326         if (write(fds[1], &status, 1) != 1) {
327             perror("daemonize. Writing to pipe\n");
328         }
329     } else
330         fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno));
331 }
332 
333 void os_set_line_buffering(void)
334 {
335     setvbuf(stdout, NULL, _IOLBF, 0);
336 }
337 
338 int qemu_create_pidfile(const char *filename)
339 {
340     char buffer[128];
341     int len;
342     int fd;
343 
344     fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
345     if (fd == -1) {
346         return -1;
347     }
348     if (lockf(fd, F_TLOCK, 0) == -1) {
349         close(fd);
350         return -1;
351     }
352     len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid());
353     if (write(fd, buffer, len) != len) {
354         close(fd);
355         return -1;
356     }
357 
358     /* keep pidfile open & locked forever */
359     return 0;
360 }
361 
362 bool is_daemonized(void)
363 {
364     return daemonize;
365 }
366 
367 int os_mlock(void)
368 {
369     int ret = 0;
370 
371     ret = mlockall(MCL_CURRENT | MCL_FUTURE);
372     if (ret < 0) {
373         perror("mlockall");
374     }
375 
376     return ret;
377 }
378