1 /*-*- Mode: C; c-basic-offset: 8 -*-*/
4 This file is part of systemd.
6 Copyright 2010 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
29 #include <sys/socket.h>
31 #include <sys/prctl.h>
32 #include <linux/sched.h>
33 #include <sys/types.h>
44 #include "securebits.h"
47 static int close_fds(int except[], unsigned n_except) {
52 /* Modifies the fds array! (sorts it) */
54 if (!(d = opendir("/proc/self/fd")))
57 while ((de = readdir(d))) {
60 if (de->d_name[0] == '.')
63 if ((r = safe_atoi(de->d_name, &fd)) < 0)
77 for (i = 0; i < n_except; i++)
78 if (except[i] == fd) {
87 if ((r = close_nointr(fd)) < 0)
96 static int shift_fds(int fds[], unsigned n_fds) {
97 int start, restart_from;
110 for (i = start; i < (int) n_fds; i++) {
113 /* Already at right index? */
117 if ((nfd = fcntl(fds[i], F_DUPFD, i+3)) < 0)
120 assert_se(close_nointr(fds[i]) == 0);
123 /* Hmm, the fd we wanted isn't free? Then
124 * let's remember that and try again from here*/
125 if (nfd != i+3 && restart_from < 0)
129 if (restart_from < 0)
132 start = restart_from;
138 static int flags_fds(int fds[], unsigned n_fds, bool nonblock) {
146 /* Drops/Sets O_NONBLOCK and FD_CLOEXEC from the file flags */
148 for (i = 0; i < n_fds; i++) {
151 if ((flags = fcntl(fds[i], F_GETFL, 0)) < 0)
157 flags &= ~O_NONBLOCK;
159 if (fcntl(fds[i], F_SETFL, flags) < 0)
162 /* We unconditionally drop FD_CLOEXEC from the fds,
163 * since after all we want to pass these fds to our
165 if ((flags = fcntl(fds[i], F_GETFD, 0)) < 0)
168 if (fcntl(fds[i], F_SETFD, flags &~FD_CLOEXEC) < 0)
175 static int replace_null_fd(int fd, int flags) {
181 if ((nfd = open("/dev/null", flags|O_NOCTTY)) < 0)
185 close_nointr_nofail(nfd);
192 static int setup_output(const ExecContext *context, const char *ident) {
197 switch (context->output) {
199 case EXEC_OUTPUT_CONSOLE:
202 case EXEC_OUTPUT_NULL:
204 if ((r = replace_null_fd(STDOUT_FILENO, O_WRONLY)) < 0 ||
205 (r = replace_null_fd(STDERR_FILENO, O_WRONLY)) < 0)
210 case EXEC_OUTPUT_KERNEL:
211 case EXEC_OUTPUT_SYSLOG: {
216 struct sockaddr_un un;
219 close_nointr(STDOUT_FILENO);
220 close_nointr(STDERR_FILENO);
222 if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
225 if (fd != STDOUT_FILENO) {
226 close_nointr_nofail(fd);
231 sa.sa.sa_family = AF_UNIX;
232 strncpy(sa.un.sun_path+1, LOGGER_SOCKET, sizeof(sa.un.sun_path)-1);
234 if (connect(fd, &sa.sa, sizeof(sa)) < 0) {
235 close_nointr_nofail(fd);
239 if (shutdown(fd, SHUT_RD) < 0) {
240 close_nointr_nofail(fd);
244 if ((fd = dup(fd)) < 0) {
245 close_nointr_nofail(fd);
249 if (fd != STDERR_FILENO) {
250 close_nointr_nofail(fd);
254 /* We speak a very simple protocol between log server
255 * and client: one line for the log destination (kmsg
256 * or syslog), followed by the priority field,
257 * followed by the process name. Since we replaced
258 * stdin/stderr we simple use stdio to write to
259 * it. Note that we use stderr, to minimize buffer
260 * flushing issues. */
266 context->output == EXEC_OUTPUT_KERNEL ? "kmsg" : "syslog",
267 context->syslog_priority,
268 context->syslog_identifier ? context->syslog_identifier : ident);
274 assert_not_reached("Unknown output type");
278 static int setup_input(const ExecContext *context) {
283 switch (context->input) {
285 case EXEC_INPUT_CONSOLE:
288 case EXEC_INPUT_NULL:
289 if ((r = replace_null_fd(STDIN_FILENO, O_RDONLY)) < 0)
295 assert_not_reached("Unknown input type");
299 static int get_group_creds(const char *groupname, gid_t *gid) {
306 /* We enforce some special rules for gid=0: in order to avoid
307 * NSS lookups for root we hardcode its data. */
309 if (streq(groupname, "root") || streq(groupname, "0")) {
314 if (safe_atolu(groupname, &lu) >= 0) {
316 g = getgrgid((gid_t) lu);
319 g = getgrnam(groupname);
323 return errno != 0 ? -errno : -ESRCH;
329 static int get_user_creds(const char **username, uid_t *uid, gid_t *gid, const char **home) {
339 /* We enforce some special rules for uid=0: in order to avoid
340 * NSS lookups for root we hardcode its data. */
342 if (streq(*username, "root") || streq(*username, "0")) {
350 if (safe_atolu(*username, &lu) >= 0) {
352 p = getpwuid((uid_t) lu);
354 /* If there are multiple users with the same id, make
355 * sure to leave $USER to the configured value instead
356 * of the first occurence in the database. However if
357 * the uid was configured by a numeric uid, then let's
358 * pick the real username from /etc/passwd. */
360 *username = p->pw_name;
363 p = getpwnam(*username);
367 return errno != 0 ? -errno : -ESRCH;
375 static int enforce_groups(const ExecContext *context, const char *username, gid_t gid) {
376 bool keep_groups = false;
381 /* Lookup and ser GID and supplementary group list. Here too
382 * we avoid NSS lookups for gid=0. */
384 if (context->group || username) {
387 if ((r = get_group_creds(context->group, &gid)) < 0)
390 /* First step, initialize groups from /etc/groups */
391 if (username && gid != 0) {
392 if (initgroups(username, gid) < 0)
398 /* Second step, set our gids */
399 if (setresgid(gid, gid, gid) < 0)
403 if (context->supplementary_groups) {
408 /* Final step, initialize any manually set supplementary groups */
409 ngroups_max = (int) sysconf(_SC_NGROUPS_MAX);
411 if (!(gids = new(gid_t, ngroups_max)))
415 if ((k = getgroups(ngroups_max, gids)) < 0) {
422 STRV_FOREACH(i, context->supplementary_groups) {
424 if (k >= ngroups_max) {
429 if ((r = get_group_creds(*i, gids+k)) < 0) {
437 if (setgroups(k, gids) < 0) {
448 static int enforce_user(const ExecContext *context, uid_t uid) {
452 /* Sets (but doesn't lookup) the uid and make sure we keep the
453 * capabilities while doing so. */
455 if (context->capabilities) {
457 static const cap_value_t bits[] = {
458 CAP_SETUID, /* Necessary so that we can run setresuid() below */
459 CAP_SETPCAP /* Necessary so that we can set PR_SET_SECUREBITS later on */
462 /* First step: If we need to keep capabilities but
463 * drop privileges we need to make sure we keep our
464 * caps, whiel we drop priviliges. */
466 int sb = context->secure_bits|SECURE_KEEP_CAPS;
468 if (prctl(PR_GET_SECUREBITS) != sb)
469 if (prctl(PR_SET_SECUREBITS, sb) < 0)
473 /* Second step: set the capabilites. This will reduce
474 * the capabilities to the minimum we need. */
476 if (!(d = cap_dup(context->capabilities)))
479 if (cap_set_flag(d, CAP_EFFECTIVE, ELEMENTSOF(bits), bits, CAP_SET) < 0 ||
480 cap_set_flag(d, CAP_PERMITTED, ELEMENTSOF(bits), bits, CAP_SET) < 0) {
486 if (cap_set_proc(d) < 0) {
495 /* Third step: actually set the uids */
496 if (setresuid(uid, uid, uid) < 0)
499 /* At this point we should have all necessary capabilities but
500 are otherwise a normal user. However, the caps might got
501 corrupted due to the setresuid() so we need clean them up
502 later. This is done outside of this call. */
507 int exec_spawn(const ExecCommand *command,
508 const ExecContext *context,
509 int *fds, unsigned n_fds,
510 bool apply_permissions,
512 CGroupBonding *cgroup_bondings,
521 assert(fds || n_fds <= 0);
523 log_debug("About to execute %s", command->path);
526 if ((r = cgroup_bonding_realize_list(cgroup_bondings)))
529 if ((pid = fork()) < 0)
535 const char *username = NULL, *home = NULL;
536 uid_t uid = (uid_t) -1;
537 gid_t gid = (gid_t) -1;
538 char **our_env = NULL, **final_env = NULL;
543 if (sigemptyset(&ss) < 0 ||
544 sigprocmask(SIG_SETMASK, &ss, NULL) < 0) {
545 r = EXIT_SIGNAL_MASK;
549 if (setpgid(0, 0) < 0) {
554 umask(context->umask);
556 if (setup_input(context) < 0) {
561 if (setup_output(context, file_name_from_path(command->path)) < 0) {
567 if ((r = cgroup_bonding_install_list(cgroup_bondings, 0)) < 0) {
572 if (context->oom_adjust_set) {
575 snprintf(t, sizeof(t), "%i", context->oom_adjust);
578 if (write_one_line_file("/proc/self/oom_adj", t) < 0) {
584 if (context->nice_set)
585 if (setpriority(PRIO_PROCESS, 0, context->nice) < 0) {
590 if (context->cpu_sched_set) {
591 struct sched_param param;
594 param.sched_priority = context->cpu_sched_priority;
596 if (sched_setscheduler(0, context->cpu_sched_policy |
597 (context->cpu_sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0), ¶m) < 0) {
598 r = EXIT_SETSCHEDULER;
603 if (context->cpu_affinity_set)
604 if (sched_setaffinity(0, sizeof(context->cpu_affinity), &context->cpu_affinity) < 0) {
605 r = EXIT_CPUAFFINITY;
609 if (context->ioprio_set)
610 if (ioprio_set(IOPRIO_WHO_PROCESS, 0, context->ioprio) < 0) {
615 if (context->timer_slack_ns_set)
616 if (prctl(PR_SET_TIMERSLACK, context->timer_slack_ns_set) < 0) {
622 username = context->user;
623 if (get_user_creds(&username, &uid, &gid, &home) < 0) {
629 if (apply_permissions)
630 if (enforce_groups(context, username, uid) < 0) {
636 if (context->root_directory)
637 if (chroot(context->root_directory) < 0) {
642 if (chdir(context->working_directory ? context->working_directory : "/") < 0) {
650 if (asprintf(&d, "%s/%s",
651 context->root_directory ? context->root_directory : "",
652 context->working_directory ? context->working_directory : "") < 0) {
666 if (close_fds(fds, n_fds) < 0 ||
667 shift_fds(fds, n_fds) < 0 ||
668 flags_fds(fds, n_fds, context->non_blocking) < 0) {
673 if (apply_permissions) {
675 for (i = 0; i < RLIMIT_NLIMITS; i++) {
676 if (!context->rlimit[i])
679 if (setrlimit(i, context->rlimit[i]) < 0) {
686 if (enforce_user(context, uid) < 0) {
691 /* PR_GET_SECUREBITS is not priviliged, while
692 * PR_SET_SECUREBITS is. So to suppress
693 * potential EPERMs we'll try not to call
694 * PR_SET_SECUREBITS unless necessary. */
695 if (prctl(PR_GET_SECUREBITS) != context->secure_bits)
696 if (prctl(PR_SET_SECUREBITS, context->secure_bits) < 0) {
701 if (context->capabilities)
702 if (cap_set_proc(context->capabilities) < 0) {
703 r = EXIT_CAPABILITIES;
708 if (!(our_env = new0(char*, 6))) {
714 if (asprintf(our_env + n_env++, "LISTEN_PID=%llu", (unsigned long long) getpid()) < 0 ||
715 asprintf(our_env + n_env++, "LISTEN_FDS=%u", n_fds) < 0) {
721 if (asprintf(our_env + n_env++, "HOME=%s", home) < 0) {
727 if (asprintf(our_env + n_env++, "LOGNAME=%s", username) < 0 ||
728 asprintf(our_env + n_env++, "USER=%s", username) < 0) {
733 if (!(final_env = strv_env_merge(environ, our_env, context->environment, NULL))) {
738 execve(command->path, command->argv, final_env);
743 strv_free(final_env);
749 log_debug("Forked %s as %llu", command->path, (unsigned long long) pid);
755 void exec_context_init(ExecContext *c) {
760 c->oom_adjust_set = false;
763 c->ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, 0);
764 c->ioprio_set = false;
765 c->cpu_sched_policy = SCHED_OTHER;
766 c->cpu_sched_priority = 0;
767 c->cpu_sched_set = false;
768 CPU_ZERO(&c->cpu_affinity);
769 c->cpu_affinity_set = false;
773 c->syslog_priority = LOG_DAEMON|LOG_INFO;
776 c->capability_bounding_set_drop = 0;
779 void exec_context_done(ExecContext *c) {
784 strv_free(c->environment);
785 c->environment = NULL;
787 for (l = 0; l < ELEMENTSOF(c->rlimit); l++) {
792 free(c->working_directory);
793 c->working_directory = NULL;
794 free(c->root_directory);
795 c->root_directory = NULL;
797 free(c->syslog_identifier);
798 c->syslog_identifier = NULL;
806 strv_free(c->supplementary_groups);
807 c->supplementary_groups = NULL;
809 if (c->capabilities) {
810 cap_free(c->capabilities);
811 c->capabilities = NULL;
815 void exec_command_free_list(ExecCommand *c) {
819 LIST_REMOVE(ExecCommand, command, c, i);
827 void exec_command_free_array(ExecCommand **c, unsigned n) {
830 for (i = 0; i < n; i++) {
831 exec_command_free_list(c[i]);
836 void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) {
848 "%sWorkingDirectory: %s\n"
849 "%sRootDirectory: %s\n"
850 "%sNonBlocking: %s\n",
852 prefix, c->working_directory ? c->working_directory : "/",
853 prefix, c->root_directory ? c->root_directory : "/",
854 prefix, yes_no(c->non_blocking));
857 for (e = c->environment; *e; e++)
858 fprintf(f, "%sEnvironment: %s\n", prefix, *e);
865 if (c->oom_adjust_set)
868 prefix, c->oom_adjust);
870 for (i = 0; i < RLIM_NLIMITS; i++)
872 fprintf(f, "%s%s: %llu\n", prefix, rlimit_to_string(i), (unsigned long long) c->rlimit[i]->rlim_max);
876 "%sIOSchedulingClass: %s\n"
877 "%sIOPriority: %i\n",
878 prefix, ioprio_class_to_string(IOPRIO_PRIO_CLASS(c->ioprio)),
879 prefix, (int) IOPRIO_PRIO_DATA(c->ioprio));
881 if (c->cpu_sched_set)
883 "%sCPUSchedulingPolicy: %s\n"
884 "%sCPUSchedulingPriority: %i\n"
885 "%sCPUSchedulingResetOnFork: %s\n",
886 prefix, sched_policy_to_string(c->cpu_sched_policy),
887 prefix, c->cpu_sched_priority,
888 prefix, yes_no(c->cpu_sched_reset_on_fork));
890 if (c->cpu_affinity_set) {
891 fprintf(f, "%sCPUAffinity:", prefix);
892 for (i = 0; i < CPU_SETSIZE; i++)
893 if (CPU_ISSET(i, &c->cpu_affinity))
894 fprintf(f, " %i", i);
898 if (c->timer_slack_ns_set)
899 fprintf(f, "%sTimerSlackNS: %lu\n", prefix, c->timer_slack_ns);
904 prefix, exec_input_to_string(c->input),
905 prefix, exec_output_to_string(c->output));
907 if (c->output == EXEC_OUTPUT_SYSLOG || c->output == EXEC_OUTPUT_KERNEL)
909 "%sSyslogFacility: %s\n"
910 "%sSyslogLevel: %s\n",
911 prefix, log_facility_to_string(LOG_FAC(c->syslog_priority)),
912 prefix, log_level_to_string(LOG_PRI(c->syslog_priority)));
914 if (c->capabilities) {
916 if ((t = cap_to_text(c->capabilities, NULL))) {
917 fprintf(f, "%sCapabilities: %s\n",
924 fprintf(f, "%sSecure Bits:%s%s%s%s%s%s\n",
926 (c->secure_bits & SECURE_KEEP_CAPS) ? " keep-caps" : "",
927 (c->secure_bits & SECURE_KEEP_CAPS_LOCKED) ? " keep-caps-locked" : "",
928 (c->secure_bits & SECURE_NO_SETUID_FIXUP) ? " no-setuid-fixup" : "",
929 (c->secure_bits & SECURE_NO_SETUID_FIXUP_LOCKED) ? " no-setuid-fixup-locked" : "",
930 (c->secure_bits & SECURE_NOROOT) ? " noroot" : "",
931 (c->secure_bits & SECURE_NOROOT_LOCKED) ? "noroot-locked" : "");
933 if (c->capability_bounding_set_drop) {
934 fprintf(f, "%sCapabilityBoundingSetDrop:", prefix);
936 for (i = 0; i <= CAP_LAST_CAP; i++)
937 if (c->capability_bounding_set_drop & (1 << i)) {
940 if ((t = cap_to_name(i))) {
941 fprintf(f, " %s", t);
950 fprintf(f, "%sUser: %s", prefix, c->user);
952 fprintf(f, "%sGroup: %s", prefix, c->group);
954 if (c->supplementary_groups) {
957 fprintf(f, "%sSupplementaryGroups:", prefix);
959 STRV_FOREACH(g, c->supplementary_groups)
960 fprintf(f, " %s", *g);
966 void exec_status_fill(ExecStatus *s, pid_t pid, int code, int status) {
972 s->timestamp = now(CLOCK_REALTIME);
975 char *exec_command_line(ExecCommand *c) {
984 STRV_FOREACH(a, c->argv)
987 if (!(n = new(char, k)))
991 STRV_FOREACH(a, c->argv) {
998 if (strpbrk(*a, WHITESPACE)) {
1009 /* FIXME: this doesn't really handle arguments that have
1010 * spaces and ticks in them */
1015 void exec_command_dump(ExecCommand *c, FILE *f, const char *prefix) {
1024 cmd = exec_command_line(c);
1027 "%sCommand Line: %s\n",
1028 prefix, cmd ? cmd : strerror(ENOMEM));
1033 void exec_command_dump_list(ExecCommand *c, FILE *f, const char *prefix) {
1039 LIST_FOREACH(command, c, c)
1040 exec_command_dump(c, f, prefix);
1043 void exec_command_append_list(ExecCommand **l, ExecCommand *e) {
1050 /* It's kinda important that we keep the order here */
1051 LIST_FIND_TAIL(ExecCommand, command, *l, end);
1052 LIST_INSERT_AFTER(ExecCommand, command, *l, end, e);
1057 static const char* const exec_output_table[_EXEC_OUTPUT_MAX] = {
1058 [EXEC_OUTPUT_CONSOLE] = "console",
1059 [EXEC_OUTPUT_NULL] = "null",
1060 [EXEC_OUTPUT_SYSLOG] = "syslog",
1061 [EXEC_OUTPUT_KERNEL] = "kernel"
1064 DEFINE_STRING_TABLE_LOOKUP(exec_output, ExecOutput);
1066 static const char* const exec_input_table[_EXEC_INPUT_MAX] = {
1067 [EXEC_INPUT_NULL] = "null",
1068 [EXEC_INPUT_CONSOLE] = "console"
1071 DEFINE_STRING_TABLE_LOOKUP(exec_input, ExecInput);