/* * 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/error-report.h" #include "qemu/log.h" #include "sysemu/runstate.h" #include "qemu/cutils.h" #ifdef CONFIG_LINUX #include <sys/prctl.h> #endif 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); } 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 } /* * 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 */ /* * Prepare to change user ID. user_id can be one of 3 forms: * - a username, in which case user ID will be changed to its uid, * with primary and supplementary groups set up too; * - a numeric uid, in which case only the uid will be set; * - a pair of numeric uid:gid. */ bool os_set_runas(const char *user_id) { unsigned long lv; const char *ep; uid_t got_uid; gid_t got_gid; int rc; user_pwd = getpwnam(user_id); if (user_pwd) { user_uid = -1; user_gid = -1; return true; } rc = qemu_strtoul(user_id, &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; } 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 const char *chroot_dir; void os_set_chroot(const char *path) { chroot_dir = path; } 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); } } } static int daemonize; static int daemon_pipe; bool is_daemonized(void) { return daemonize; } int os_set_daemonize(bool d) { daemonize = d; return 0; } void os_daemonize(void) { if (daemonize) { pid_t pid; int fds[2]; if (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) { 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]; 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); } fd = RETRY_ON_EINTR(qemu_open_old("/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_log_enabled()) { 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); } int os_mlock(void) { #ifdef HAVE_MLOCKALL int ret = 0; ret = mlockall(MCL_CURRENT | MCL_FUTURE); if (ret < 0) { error_report("mlockall: %s", strerror(errno)); } return ret; #else return -ENOSYS; #endif }