/* * 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 "qemu/osdep.h" #include <sys/wait.h> #include <pwd.h> #include <grp.h> #include <libgen.h> #include "qemu-common.h" /* Needed early for CONFIG_BSD etc. */ #include "net/slirp.h" #include "qemu-options.h" #include "qemu/error-report.h" #include "qemu/log.h" #include "sysemu/runstate.h" #include "qemu/cutils.h" #ifdef CONFIG_LINUX #include <sys/prctl.h> #endif /* * Must set all three of these at once. * Legal combinations are unset by name by uid */ static struct passwd *user_pwd; /* NULL non-NULL NULL */ static uid_t user_uid = (uid_t)-1; /* -1 -1 >=0 */ static gid_t user_gid = (gid_t)-1; /* -1 -1 >=0 */ static const char *chroot_dir; static int daemonize; static int daemon_pipe; 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, siginfo_t *info, void *c) { qemu_system_killed(info->si_signo, info->si_pid); } void os_setup_signal_handling(void) { struct sigaction act; memset(&act, 0, sizeof(act)); act.sa_sigaction = termsig_handler; act.sa_flags = SA_SIGINFO; sigaction(SIGINT, &act, NULL); sigaction(SIGHUP, &act, NULL); sigaction(SIGTERM, &act, NULL); } /* * Find a likely location for support files using the location of the binary. * When running from the build tree this will be "$bindir/../pc-bios". * Otherwise, this is CONFIG_QEMU_DATADIR. */ char *os_find_datadir(void) { g_autofree char *exec_dir = NULL; g_autofree char *dir = NULL; exec_dir = qemu_get_exec_dir(); g_return_val_if_fail(exec_dir != NULL, NULL); dir = g_build_filename(exec_dir, "..", "pc-bios", NULL); if (g_file_test(dir, G_FILE_TEST_IS_DIR)) { return g_steal_pointer(&dir); } return g_strdup(CONFIG_QEMU_DATADIR); } void os_set_proc_name(const char *s) { #if defined(PR_SET_NAME) char name[16]; if (!s) return; pstrcpy(name, sizeof(name), s); /* 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)) { error_report("unable to change process name: %s", strerror(errno)); exit(1); } #else error_report("Change of process name not supported by your OS"); exit(1); #endif } static bool os_parse_runas_uid_gid(const char *optarg) { unsigned long lv; const char *ep; uid_t got_uid; gid_t got_gid; int rc; rc = qemu_strtoul(optarg, &ep, 0, &lv); got_uid = lv; /* overflow here is ID in C99 */ if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) { return false; } rc = qemu_strtoul(ep + 1, 0, 0, &lv); got_gid = lv; /* overflow here is ID in C99 */ if (rc || got_gid != lv || got_gid == (gid_t)-1) { return false; } user_pwd = NULL; user_uid = got_uid; user_gid = got_gid; return true; } /* * Parse OS specific command line options. * return 0 if option handled, -1 otherwise */ int os_parse_cmd_args(int index, const char *optarg) { switch (index) { case QEMU_OPTION_runas: user_pwd = getpwnam(optarg); if (user_pwd) { user_uid = -1; user_gid = -1; } else if (!os_parse_runas_uid_gid(optarg)) { error_report("User \"%s\" doesn't exist" " (and is not <uid>:<gid>)", optarg); exit(1); } break; case QEMU_OPTION_chroot: chroot_dir = optarg; break; case QEMU_OPTION_daemonize: daemonize = 1; break; #if defined(CONFIG_LINUX) case QEMU_OPTION_enablefips: fips_set_state(true); break; #endif default: return -1; } return 0; } static void change_process_uid(void) { assert((user_uid == (uid_t)-1) || user_pwd == NULL); assert((user_uid == (uid_t)-1) == (user_gid == (gid_t)-1)); if (user_pwd || user_uid != (uid_t)-1) { gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid; uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid; if (setgid(intended_gid) < 0) { error_report("Failed to setgid(%d)", intended_gid); exit(1); } if (user_pwd) { if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { error_report("Failed to initgroups(\"%s\", %d)", user_pwd->pw_name, user_pwd->pw_gid); exit(1); } } else { if (setgroups(1, &user_gid) < 0) { error_report("Failed to setgroups(1, [%d])", user_gid); exit(1); } } if (setuid(intended_uid) < 0) { error_report("Failed to setuid(%d)", intended_uid); exit(1); } if (setuid(0) != -1) { error_report("Dropping privileges failed"); exit(1); } } } static void change_root(void) { if (chroot_dir) { if (chroot(chroot_dir) < 0) { error_report("chroot failed"); exit(1); } if (chdir("/")) { error_report("not able to chdir to /: %s", strerror(errno)); exit(1); } } } void os_daemonize(void) { if (daemonize) { pid_t pid; int fds[2]; if (pipe(fds) == -1) { exit(1); } pid = fork(); if (pid > 0) { uint8_t status; ssize_t len; close(fds[1]); do { len = read(fds[0], &status, 1); } while (len < 0 && errno == EINTR); /* only exit successfully if our child actually wrote * a one-byte zero to our pipe, upon successful init */ exit(len == 1 && status == 0 ? 0 : 1); } else if (pid < 0) { exit(1); } close(fds[0]); daemon_pipe = fds[1]; qemu_set_cloexec(daemon_pipe); 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) { if (chdir("/")) { error_report("not able to chdir to /: %s", strerror(errno)); exit(1); } TFR(fd = qemu_open("/dev/null", O_RDWR)); if (fd == -1) { exit(1); } } change_root(); change_process_uid(); if (daemonize) { uint8_t status = 0; ssize_t len; dup2(fd, 0); dup2(fd, 1); /* In case -D is given do not redirect stderr to /dev/null */ if (!qemu_logfile) { dup2(fd, 2); } close(fd); do { len = write(daemon_pipe, &status, 1); } while (len < 0 && errno == EINTR); if (len != 1) { exit(1); } } } void os_set_line_buffering(void) { setvbuf(stdout, NULL, _IOLBF, 0); } bool is_daemonized(void) { return daemonize; } int os_mlock(void) { int ret = 0; ret = mlockall(MCL_CURRENT | MCL_FUTURE); if (ret < 0) { error_report("mlockall: %s", strerror(errno)); } return ret; }