/* * os-posix.c * * Copyright (c) 2003-2008 Fabrice Bellard * Copyright (c) 2010 Red Hat, Inc. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include <unistd.h> #include <fcntl.h> #include <signal.h> #include <sys/types.h> #include <sys/wait.h> /*needed for MAP_POPULATE before including qemu-options.h */ #include <sys/mman.h> #include <pwd.h> #include <libgen.h> /* Needed early for CONFIG_BSD etc. */ #include "config-host.h" #include "sysemu.h" #include "net/slirp.h" #include "qemu-options.h" #ifdef CONFIG_LINUX #include <sys/prctl.h> #endif static struct passwd *user_pwd; static const char *chroot_dir; static int daemonize; static int fds[2]; void os_setup_early_signal_handling(void) { struct sigaction act; sigfillset(&act.sa_mask); act.sa_flags = 0; act.sa_handler = SIG_IGN; sigaction(SIGPIPE, &act, NULL); } static void termsig_handler(int signal) { qemu_system_shutdown_request(); } static void sigchld_handler(int signal) { waitpid(-1, NULL, WNOHANG); } void os_setup_signal_handling(void) { struct sigaction act; memset(&act, 0, sizeof(act)); act.sa_handler = termsig_handler; sigaction(SIGINT, &act, NULL); sigaction(SIGHUP, &act, NULL); sigaction(SIGTERM, &act, NULL); act.sa_handler = sigchld_handler; act.sa_flags = SA_NOCLDSTOP; sigaction(SIGCHLD, &act, NULL); } /* Find a likely location for support files using the location of the binary. For installed binaries this will be "$bindir/../share/qemu". When running from the build tree this will be "$bindir/../pc-bios". */ #define SHARE_SUFFIX "/share/qemu" #define BUILD_SUFFIX "/pc-bios" char *os_find_datadir(const char *argv0) { char *dir; char *p = NULL; char *res; char buf[PATH_MAX]; size_t max_len; #if defined(__linux__) { int len; len = readlink("/proc/self/exe", buf, sizeof(buf) - 1); if (len > 0) { buf[len] = 0; p = buf; } } #elif defined(__FreeBSD__) { static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1}; size_t len = sizeof(buf) - 1; *buf = '\0'; if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) && *buf) { buf[sizeof(buf) - 1] = '\0'; p = buf; } } #endif /* If we don't have any way of figuring out the actual executable location then try argv[0]. */ if (!p) { p = realpath(argv0, buf); if (!p) { return NULL; } } dir = dirname(p); dir = dirname(dir); max_len = strlen(dir) + MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1; res = qemu_mallocz(max_len); snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX); if (access(res, R_OK)) { snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX); if (access(res, R_OK)) { qemu_free(res); res = NULL; } } return res; } #undef SHARE_SUFFIX #undef BUILD_SUFFIX void os_set_proc_name(const char *s) { #if defined(PR_SET_NAME) char name[16]; if (!s) return; name[sizeof(name) - 1] = 0; strncpy(name, s, sizeof(name)); /* Could rewrite argv[0] too, but that's a bit more complicated. This simple way is enough for `top'. */ if (prctl(PR_SET_NAME, name)) { perror("unable to change process name"); exit(1); } #else fprintf(stderr, "Change of process name not supported by your OS\n"); exit(1); #endif } /* * Parse OS specific command line options. * return 0 if option handled, -1 otherwise */ void os_parse_cmd_args(int index, const char *optarg) { switch (index) { #ifdef CONFIG_SLIRP case QEMU_OPTION_smb: if (net_slirp_smb(optarg) < 0) exit(1); break; #endif case QEMU_OPTION_runas: user_pwd = getpwnam(optarg); if (!user_pwd) { fprintf(stderr, "User \"%s\" doesn't exist\n", optarg); exit(1); } break; case QEMU_OPTION_chroot: chroot_dir = optarg; break; case QEMU_OPTION_daemonize: daemonize = 1; break; } return; } static void change_process_uid(void) { if (user_pwd) { if (setgid(user_pwd->pw_gid) < 0) { fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid); exit(1); } if (setuid(user_pwd->pw_uid) < 0) { fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid); exit(1); } if (setuid(0) != -1) { fprintf(stderr, "Dropping privileges failed\n"); exit(1); } } } static void change_root(void) { if (chroot_dir) { if (chroot(chroot_dir) < 0) { fprintf(stderr, "chroot failed\n"); exit(1); } if (chdir("/")) { perror("not able to chdir to /"); exit(1); } } } void os_daemonize(void) { if (daemonize) { pid_t pid; if (pipe(fds) == -1) exit(1); pid = fork(); if (pid > 0) { uint8_t status; ssize_t len; close(fds[1]); again: len = read(fds[0], &status, 1); if (len == -1 && (errno == EINTR)) goto again; if (len != 1) exit(1); else if (status == 1) { fprintf(stderr, "Could not acquire pidfile: %s\n", strerror(errno)); exit(1); } else exit(0); } else if (pid < 0) exit(1); close(fds[0]); qemu_set_cloexec(fds[1]); setsid(); pid = fork(); if (pid > 0) exit(0); else if (pid < 0) exit(1); umask(027); signal(SIGTSTP, SIG_IGN); signal(SIGTTOU, SIG_IGN); signal(SIGTTIN, SIG_IGN); } } void os_setup_post(void) { int fd = 0; if (daemonize) { uint8_t status = 0; ssize_t len; again1: len = write(fds[1], &status, 1); if (len == -1 && (errno == EINTR)) goto again1; if (len != 1) exit(1); if (chdir("/")) { perror("not able to chdir to /"); exit(1); } TFR(fd = qemu_open("/dev/null", O_RDWR)); if (fd == -1) exit(1); } change_root(); change_process_uid(); if (daemonize) { dup2(fd, 0); dup2(fd, 1); dup2(fd, 2); close(fd); } } void os_pidfile_error(void) { if (daemonize) { uint8_t status = 1; if (write(fds[1], &status, 1) != 1) { perror("daemonize. Writing to pipe\n"); } } else fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno)); } void os_set_line_buffering(void) { setvbuf(stdout, NULL, _IOLBF, 0); }