Annotation of qemu/os-posix.c, revision 1.1.1.5

1.1       root        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>
1.1.1.3   root       34: #include <grp.h>
1.1       root       35: #include <libgen.h>
                     36: 
                     37: /* Needed early for CONFIG_BSD etc. */
                     38: #include "config-host.h"
                     39: #include "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: 
1.1.1.5 ! root       47: #ifdef __FreeBSD__
        !            48: #include <sys/sysctl.h>
1.1.1.2   root       49: #endif
                     50: 
1.1       root       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: 
1.1.1.3   root       65: static void termsig_handler(int signal, siginfo_t *info, void *c)
1.1       root       66: {
1.1.1.3   root       67:     qemu_system_killed(info->si_signo, info->si_pid);
1.1       root       68: }
                     69: 
                     70: void os_setup_signal_handling(void)
                     71: {
                     72:     struct sigaction act;
                     73: 
                     74:     memset(&act, 0, sizeof(act));
1.1.1.3   root       75:     act.sa_sigaction = termsig_handler;
                     76:     act.sa_flags = SA_SIGINFO;
1.1       root       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';
1.1.1.2   root      110:         if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
1.1       root      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;
1.1.1.4   root      130:     res = g_malloc0(max_len);
1.1       root      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)) {
1.1.1.4   root      135:             g_free(res);
1.1       root      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:     name[sizeof(name) - 1] = 0;
                    152:     strncpy(name, s, sizeof(name));
                    153:     /* Could rewrite argv[0] too, but that's a bit more complicated.
                    154:        This simple way is enough for `top'. */
                    155:     if (prctl(PR_SET_NAME, name)) {
                    156:         perror("unable to change process name");
                    157:         exit(1);
                    158:     }
                    159: #else
                    160:     fprintf(stderr, "Change of process name not supported by your OS\n");
                    161:     exit(1);
                    162: #endif
                    163: }
                    164: 
                    165: /*
                    166:  * Parse OS specific command line options.
                    167:  * return 0 if option handled, -1 otherwise
                    168:  */
                    169: void os_parse_cmd_args(int index, const char *optarg)
                    170: {
                    171:     switch (index) {
                    172: #ifdef CONFIG_SLIRP
                    173:     case QEMU_OPTION_smb:
                    174:         if (net_slirp_smb(optarg) < 0)
                    175:             exit(1);
                    176:         break;
                    177: #endif
                    178:     case QEMU_OPTION_runas:
                    179:         user_pwd = getpwnam(optarg);
                    180:         if (!user_pwd) {
                    181:             fprintf(stderr, "User \"%s\" doesn't exist\n", optarg);
                    182:             exit(1);
                    183:         }
                    184:         break;
                    185:     case QEMU_OPTION_chroot:
                    186:         chroot_dir = optarg;
                    187:         break;
                    188:     case QEMU_OPTION_daemonize:
                    189:         daemonize = 1;
                    190:         break;
                    191:     }
                    192:     return;
                    193: }
                    194: 
                    195: static void change_process_uid(void)
                    196: {
                    197:     if (user_pwd) {
                    198:         if (setgid(user_pwd->pw_gid) < 0) {
                    199:             fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid);
                    200:             exit(1);
                    201:         }
1.1.1.3   root      202:         if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
                    203:             fprintf(stderr, "Failed to initgroups(\"%s\", %d)\n",
                    204:                     user_pwd->pw_name, user_pwd->pw_gid);
                    205:             exit(1);
                    206:         }
1.1       root      207:         if (setuid(user_pwd->pw_uid) < 0) {
                    208:             fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid);
                    209:             exit(1);
                    210:         }
                    211:         if (setuid(0) != -1) {
                    212:             fprintf(stderr, "Dropping privileges failed\n");
                    213:             exit(1);
                    214:         }
                    215:     }
                    216: }
                    217: 
                    218: static void change_root(void)
                    219: {
                    220:     if (chroot_dir) {
                    221:         if (chroot(chroot_dir) < 0) {
                    222:             fprintf(stderr, "chroot failed\n");
                    223:             exit(1);
                    224:         }
                    225:         if (chdir("/")) {
                    226:             perror("not able to chdir to /");
                    227:             exit(1);
                    228:         }
                    229:     }
                    230: 
                    231: }
                    232: 
                    233: void os_daemonize(void)
                    234: {
                    235:     if (daemonize) {
                    236:        pid_t pid;
                    237: 
                    238:        if (pipe(fds) == -1)
                    239:            exit(1);
                    240: 
                    241:        pid = fork();
                    242:        if (pid > 0) {
                    243:            uint8_t status;
                    244:            ssize_t len;
                    245: 
                    246:            close(fds[1]);
                    247: 
                    248:        again:
                    249:             len = read(fds[0], &status, 1);
                    250:             if (len == -1 && (errno == EINTR))
                    251:                 goto again;
                    252: 
                    253:             if (len != 1)
                    254:                 exit(1);
                    255:             else if (status == 1) {
                    256:                 fprintf(stderr, "Could not acquire pidfile: %s\n", strerror(errno));
                    257:                 exit(1);
                    258:             } else
                    259:                 exit(0);
                    260:        } else if (pid < 0)
                    261:             exit(1);
                    262: 
                    263:        close(fds[0]);
                    264:        qemu_set_cloexec(fds[1]);
                    265: 
                    266:        setsid();
                    267: 
                    268:        pid = fork();
                    269:        if (pid > 0)
                    270:            exit(0);
                    271:        else if (pid < 0)
                    272:            exit(1);
                    273: 
                    274:        umask(027);
                    275: 
                    276:         signal(SIGTSTP, SIG_IGN);
                    277:         signal(SIGTTOU, SIG_IGN);
                    278:         signal(SIGTTIN, SIG_IGN);
                    279:     }
                    280: }
                    281: 
                    282: void os_setup_post(void)
                    283: {
                    284:     int fd = 0;
                    285: 
                    286:     if (daemonize) {
                    287:        uint8_t status = 0;
                    288:        ssize_t len;
                    289: 
                    290:     again1:
                    291:        len = write(fds[1], &status, 1);
                    292:        if (len == -1 && (errno == EINTR))
                    293:            goto again1;
                    294: 
                    295:        if (len != 1)
                    296:            exit(1);
                    297: 
                    298:         if (chdir("/")) {
                    299:             perror("not able to chdir to /");
                    300:             exit(1);
                    301:         }
                    302:        TFR(fd = qemu_open("/dev/null", O_RDWR));
                    303:        if (fd == -1)
                    304:            exit(1);
                    305:     }
                    306: 
                    307:     change_root();
                    308:     change_process_uid();
                    309: 
                    310:     if (daemonize) {
                    311:         dup2(fd, 0);
                    312:         dup2(fd, 1);
                    313:         dup2(fd, 2);
                    314: 
                    315:         close(fd);
                    316:     }
                    317: }
                    318: 
                    319: void os_pidfile_error(void)
                    320: {
                    321:     if (daemonize) {
                    322:         uint8_t status = 1;
                    323:         if (write(fds[1], &status, 1) != 1) {
                    324:             perror("daemonize. Writing to pipe\n");
                    325:         }
                    326:     } else
                    327:         fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno));
                    328: }
                    329: 
                    330: void os_set_line_buffering(void)
                    331: {
                    332:     setvbuf(stdout, NULL, _IOLBF, 0);
                    333: }
1.1.1.2   root      334: 
                    335: int qemu_create_pidfile(const char *filename)
                    336: {
                    337:     char buffer[128];
                    338:     int len;
                    339:     int fd;
                    340: 
                    341:     fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
                    342:     if (fd == -1) {
                    343:         return -1;
                    344:     }
                    345:     if (lockf(fd, F_TLOCK, 0) == -1) {
1.1.1.4   root      346:         close(fd);
1.1.1.2   root      347:         return -1;
                    348:     }
1.1.1.3   root      349:     len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid());
1.1.1.2   root      350:     if (write(fd, buffer, len) != len) {
1.1.1.4   root      351:         close(fd);
1.1.1.2   root      352:         return -1;
                    353:     }
                    354: 
1.1.1.5 ! root      355:     /* keep pidfile open & locked forever */
1.1.1.2   root      356:     return 0;
                    357: }

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