target-cris/translate.c: fix out of bounds read
[qemu.git] / os-posix.c
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 static struct passwd *user_pwd;
48 static const char *chroot_dir;
49 static int daemonize;
50 static int daemon_pipe;
51
52 void os_setup_early_signal_handling(void)
53 {
54 struct sigaction act;
55 sigfillset(&act.sa_mask);
56 act.sa_flags = 0;
57 act.sa_handler = SIG_IGN;
58 sigaction(SIGPIPE, &act, NULL);
59 }
60
61 static void termsig_handler(int signal, siginfo_t *info, void *c)
62 {
63 qemu_system_killed(info->si_signo, info->si_pid);
64 }
65
66 void os_setup_signal_handling(void)
67 {
68 struct sigaction act;
69
70 memset(&act, 0, sizeof(act));
71 act.sa_sigaction = termsig_handler;
72 act.sa_flags = SA_SIGINFO;
73 sigaction(SIGINT, &act, NULL);
74 sigaction(SIGHUP, &act, NULL);
75 sigaction(SIGTERM, &act, NULL);
76 }
77
78 /* Find a likely location for support files using the location of the binary.
79 For installed binaries this will be "$bindir/../share/qemu". When
80 running from the build tree this will be "$bindir/../pc-bios". */
81 #define SHARE_SUFFIX "/share/qemu"
82 #define BUILD_SUFFIX "/pc-bios"
83 char *os_find_datadir(void)
84 {
85 char *dir, *exec_dir;
86 char *res;
87 size_t max_len;
88
89 exec_dir = qemu_get_exec_dir();
90 if (exec_dir == NULL) {
91 return NULL;
92 }
93 dir = dirname(exec_dir);
94
95 max_len = strlen(dir) +
96 MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1;
97 res = g_malloc0(max_len);
98 snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX);
99 if (access(res, R_OK)) {
100 snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX);
101 if (access(res, R_OK)) {
102 g_free(res);
103 res = NULL;
104 }
105 }
106
107 g_free(exec_dir);
108 return res;
109 }
110 #undef SHARE_SUFFIX
111 #undef BUILD_SUFFIX
112
113 void os_set_proc_name(const char *s)
114 {
115 #if defined(PR_SET_NAME)
116 char name[16];
117 if (!s)
118 return;
119 pstrcpy(name, sizeof(name), s);
120 /* Could rewrite argv[0] too, but that's a bit more complicated.
121 This simple way is enough for `top'. */
122 if (prctl(PR_SET_NAME, name)) {
123 perror("unable to change process name");
124 exit(1);
125 }
126 #else
127 fprintf(stderr, "Change of process name not supported by your OS\n");
128 exit(1);
129 #endif
130 }
131
132 /*
133 * Parse OS specific command line options.
134 * return 0 if option handled, -1 otherwise
135 */
136 void os_parse_cmd_args(int index, const char *optarg)
137 {
138 switch (index) {
139 #ifdef CONFIG_SLIRP
140 case QEMU_OPTION_smb:
141 if (net_slirp_smb(optarg) < 0)
142 exit(1);
143 break;
144 #endif
145 case QEMU_OPTION_runas:
146 user_pwd = getpwnam(optarg);
147 if (!user_pwd) {
148 fprintf(stderr, "User \"%s\" doesn't exist\n", optarg);
149 exit(1);
150 }
151 break;
152 case QEMU_OPTION_chroot:
153 chroot_dir = optarg;
154 break;
155 case QEMU_OPTION_daemonize:
156 daemonize = 1;
157 break;
158 #if defined(CONFIG_LINUX)
159 case QEMU_OPTION_enablefips:
160 fips_set_state(true);
161 break;
162 #endif
163 }
164 }
165
166 static void change_process_uid(void)
167 {
168 if (user_pwd) {
169 if (setgid(user_pwd->pw_gid) < 0) {
170 fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid);
171 exit(1);
172 }
173 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
174 fprintf(stderr, "Failed to initgroups(\"%s\", %d)\n",
175 user_pwd->pw_name, user_pwd->pw_gid);
176 exit(1);
177 }
178 if (setuid(user_pwd->pw_uid) < 0) {
179 fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid);
180 exit(1);
181 }
182 if (setuid(0) != -1) {
183 fprintf(stderr, "Dropping privileges failed\n");
184 exit(1);
185 }
186 }
187 }
188
189 static void change_root(void)
190 {
191 if (chroot_dir) {
192 if (chroot(chroot_dir) < 0) {
193 fprintf(stderr, "chroot failed\n");
194 exit(1);
195 }
196 if (chdir("/")) {
197 perror("not able to chdir to /");
198 exit(1);
199 }
200 }
201
202 }
203
204 void os_daemonize(void)
205 {
206 if (daemonize) {
207 pid_t pid;
208 int fds[2];
209
210 if (pipe(fds) == -1) {
211 exit(1);
212 }
213
214 pid = fork();
215 if (pid > 0) {
216 uint8_t status;
217 ssize_t len;
218
219 close(fds[1]);
220
221 do {
222 len = read(fds[0], &status, 1);
223 } while (len < 0 && errno == EINTR);
224
225 /* only exit successfully if our child actually wrote
226 * a one-byte zero to our pipe, upon successful init */
227 exit(len == 1 && status == 0 ? 0 : 1);
228
229 } else if (pid < 0) {
230 exit(1);
231 }
232
233 close(fds[0]);
234 daemon_pipe = fds[1];
235 qemu_set_cloexec(daemon_pipe);
236
237 setsid();
238
239 pid = fork();
240 if (pid > 0) {
241 exit(0);
242 } else if (pid < 0) {
243 exit(1);
244 }
245 umask(027);
246
247 signal(SIGTSTP, SIG_IGN);
248 signal(SIGTTOU, SIG_IGN);
249 signal(SIGTTIN, SIG_IGN);
250 }
251 }
252
253 void os_setup_post(void)
254 {
255 int fd = 0;
256
257 if (daemonize) {
258 if (chdir("/")) {
259 perror("not able to chdir to /");
260 exit(1);
261 }
262 TFR(fd = qemu_open("/dev/null", O_RDWR));
263 if (fd == -1) {
264 exit(1);
265 }
266 }
267
268 change_root();
269 change_process_uid();
270
271 if (daemonize) {
272 uint8_t status = 0;
273 ssize_t len;
274
275 dup2(fd, 0);
276 dup2(fd, 1);
277 dup2(fd, 2);
278
279 close(fd);
280
281 do {
282 len = write(daemon_pipe, &status, 1);
283 } while (len < 0 && errno == EINTR);
284 if (len != 1) {
285 exit(1);
286 }
287 }
288 }
289
290 void os_set_line_buffering(void)
291 {
292 setvbuf(stdout, NULL, _IOLBF, 0);
293 }
294
295 int qemu_create_pidfile(const char *filename)
296 {
297 char buffer[128];
298 int len;
299 int fd;
300
301 fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
302 if (fd == -1) {
303 return -1;
304 }
305 if (lockf(fd, F_TLOCK, 0) == -1) {
306 close(fd);
307 return -1;
308 }
309 len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid());
310 if (write(fd, buffer, len) != len) {
311 close(fd);
312 return -1;
313 }
314
315 /* keep pidfile open & locked forever */
316 return 0;
317 }
318
319 bool is_daemonized(void)
320 {
321 return daemonize;
322 }
323
324 int os_mlock(void)
325 {
326 int ret = 0;
327
328 ret = mlockall(MCL_CURRENT | MCL_FUTURE);
329 if (ret < 0) {
330 perror("mlockall");
331 }
332
333 return ret;
334 }