/* SPDX-License-Identifier: LGPL-2.1+ */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if HAVE_VALGRIND_VALGRIND_H #include #endif #include "alloc-util.h" #include "architecture.h" #include "escape.h" #include "fd-util.h" #include "fileio.h" #include "fs-util.h" #include "ioprio.h" #include "log.h" #include "macro.h" #include "missing.h" #include "process-util.h" #include "raw-clone.h" #include "signal-util.h" #include "stat-util.h" #include "string-table.h" #include "string-util.h" #include "terminal-util.h" #include "user-util.h" #include "util.h" int get_process_state(pid_t pid) { const char *p; char state; int r; _cleanup_free_ char *line = NULL; assert(pid >= 0); p = procfs_file_alloca(pid, "stat"); r = read_one_line_file(p, &line); if (r == -ENOENT) return -ESRCH; if (r < 0) return r; p = strrchr(line, ')'); if (!p) return -EIO; p++; if (sscanf(p, " %c", &state) != 1) return -EIO; return (unsigned char) state; } int get_process_comm(pid_t pid, char **ret) { _cleanup_free_ char *escaped = NULL, *comm = NULL; const char *p; int r; assert(ret); assert(pid >= 0); escaped = new(char, TASK_COMM_LEN); if (!escaped) return -ENOMEM; p = procfs_file_alloca(pid, "comm"); r = read_one_line_file(p, &comm); if (r == -ENOENT) return -ESRCH; if (r < 0) return r; /* Escape unprintable characters, just in case, but don't grow the string beyond the underlying size */ cellescape(escaped, TASK_COMM_LEN, comm); *ret = TAKE_PTR(escaped); return 0; } int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char **line) { _cleanup_fclose_ FILE *f = NULL; bool space = false; char *k, *ans = NULL; const char *p; int c; assert(line); assert(pid >= 0); /* Retrieves a process' command line. Replaces unprintable characters while doing so by whitespace (coalescing * multiple sequential ones into one). If max_length is != 0 will return a string of the specified size at most * (the trailing NUL byte does count towards the length here!), abbreviated with a "..." ellipsis. If * comm_fallback is true and the process has no command line set (the case for kernel threads), or has a * command line that resolves to the empty string will return the "comm" name of the process instead. * * Returns -ESRCH if the process doesn't exist, and -ENOENT if the process has no command line (and * comm_fallback is false). Returns 0 and sets *line otherwise. */ p = procfs_file_alloca(pid, "cmdline"); f = fopen(p, "re"); if (!f) { if (errno == ENOENT) return -ESRCH; return -errno; } (void) __fsetlocking(f, FSETLOCKING_BYCALLER); if (max_length == 1) { /* If there's only room for one byte, return the empty string */ ans = new0(char, 1); if (!ans) return -ENOMEM; *line = ans; return 0; } else if (max_length == 0) { size_t len = 0, allocated = 0; while ((c = getc(f)) != EOF) { if (!GREEDY_REALLOC(ans, allocated, len+3)) { free(ans); return -ENOMEM; } if (isprint(c)) { if (space) { ans[len++] = ' '; space = false; } ans[len++] = c; } else if (len > 0) space = true; } if (len > 0) ans[len] = '\0'; else ans = mfree(ans); } else { bool dotdotdot = false; size_t left; ans = new(char, max_length); if (!ans) return -ENOMEM; k = ans; left = max_length; while ((c = getc(f)) != EOF) { if (isprint(c)) { if (space) { if (left <= 2) { dotdotdot = true; break; } *(k++) = ' '; left--; space = false; } if (left <= 1) { dotdotdot = true; break; } *(k++) = (char) c; left--; } else if (k > ans) space = true; } if (dotdotdot) { if (max_length <= 4) { k = ans; left = max_length; } else { k = ans + max_length - 4; left = 4; /* Eat up final spaces */ while (k > ans && isspace(k[-1])) { k--; left++; } } strncpy(k, "...", left-1); k[left-1] = 0; } else *k = 0; } /* Kernel threads have no argv[] */ if (isempty(ans)) { _cleanup_free_ char *t = NULL; int h; free(ans); if (!comm_fallback) return -ENOENT; h = get_process_comm(pid, &t); if (h < 0) return h; if (max_length == 0) ans = strjoin("[", t, "]"); else { size_t l; l = strlen(t); if (l + 3 <= max_length) ans = strjoin("[", t, "]"); else if (max_length <= 6) { ans = new(char, max_length); if (!ans) return -ENOMEM; memcpy(ans, "[...]", max_length-1); ans[max_length-1] = 0; } else { t[max_length - 6] = 0; /* Chop off final spaces */ delete_trailing_chars(t, WHITESPACE); ans = strjoin("[", t, "...]"); } } if (!ans) return -ENOMEM; } *line = ans; return 0; } int rename_process(const char name[]) { static size_t mm_size = 0; static char *mm = NULL; bool truncated = false; size_t l; /* This is a like a poor man's setproctitle(). It changes the comm field, argv[0], and also the glibc's * internally used name of the process. For the first one a limit of 16 chars applies; to the second one in * many cases one of 10 (i.e. length of "/sbin/init") — however if we have CAP_SYS_RESOURCES it is unbounded; * to the third one 7 (i.e. the length of "systemd". If you pass a longer string it will likely be * truncated. * * Returns 0 if a name was set but truncated, > 0 if it was set but not truncated. */ if (isempty(name)) return -EINVAL; /* let's not confuse users unnecessarily with an empty name */ if (!is_main_thread()) return -EPERM; /* Let's not allow setting the process name from other threads than the main one, as we * cache things without locking, and we make assumptions that PR_SET_NAME sets the * process name that isn't correct on any other threads */ l = strlen(name); /* First step, change the comm field. The main thread's comm is identical to the process comm. This means we * can use PR_SET_NAME, which sets the thread name for the calling thread. */ if (prctl(PR_SET_NAME, name) < 0) log_debug_errno(errno, "PR_SET_NAME failed: %m"); if (l >= TASK_COMM_LEN) /* Linux process names can be 15 chars at max */ truncated = true; /* Second step, change glibc's ID of the process name. */ if (program_invocation_name) { size_t k; k = strlen(program_invocation_name); strncpy(program_invocation_name, name, k); if (l > k) truncated = true; } /* Third step, completely replace the argv[] array the kernel maintains for us. This requires privileges, but * has the advantage that the argv[] array is exactly what we want it to be, and not filled up with zeros at * the end. This is the best option for changing /proc/self/cmdline. */ /* Let's not bother with this if we don't have euid == 0. Strictly speaking we should check for the * CAP_SYS_RESOURCE capability which is independent of the euid. In our own code the capability generally is * present only for euid == 0, hence let's use this as quick bypass check, to avoid calling mmap() if * PR_SET_MM_ARG_{START,END} fails with EPERM later on anyway. After all geteuid() is dead cheap to call, but * mmap() is not. */ if (geteuid() != 0) log_debug("Skipping PR_SET_MM, as we don't have privileges."); else if (mm_size < l+1) { size_t nn_size; char *nn; nn_size = PAGE_ALIGN(l+1); nn = mmap(NULL, nn_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); if (nn == MAP_FAILED) { log_debug_errno(errno, "mmap() failed: %m"); goto use_saved_argv; } strncpy(nn, name, nn_size); /* Now, let's tell the kernel about this new memory */ if (prctl(PR_SET_MM, PR_SET_MM_ARG_START, (unsigned long) nn, 0, 0) < 0) { /* HACK: prctl() API is kind of dumb on this point. The existing end address may already be * below the desired start address, in which case the kernel may have kicked this back due * to a range-check failure (see linux/kernel/sys.c:validate_prctl_map() to see this in * action). The proper solution would be to have a prctl() API that could set both start+end * simultaneously, or at least let us query the existing address to anticipate this condition * and respond accordingly. For now, we can only guess at the cause of this failure and try * a workaround--which will briefly expand the arg space to something potentially huge before * resizing it to what we want. */ log_debug_errno(errno, "PR_SET_MM_ARG_START failed, attempting PR_SET_MM_ARG_END hack: %m"); if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, (unsigned long) nn + l + 1, 0, 0) < 0) { log_debug_errno(errno, "PR_SET_MM_ARG_END hack failed, proceeding without: %m"); (void) munmap(nn, nn_size); goto use_saved_argv; } if (prctl(PR_SET_MM, PR_SET_MM_ARG_START, (unsigned long) nn, 0, 0) < 0) { log_debug_errno(errno, "PR_SET_MM_ARG_START still failed, proceeding without: %m"); goto use_saved_argv; } } else { /* And update the end pointer to the new end, too. If this fails, we don't really know what * to do, it's pretty unlikely that we can rollback, hence we'll just accept the failure, * and continue. */ if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, (unsigned long) nn + l + 1, 0, 0) < 0) log_debug_errno(errno, "PR_SET_MM_ARG_END failed, proceeding without: %m"); } if (mm) (void) munmap(mm, mm_size); mm = nn; mm_size = nn_size; } else { strncpy(mm, name, mm_size); /* Update the end pointer, continuing regardless of any failure. */ if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, (unsigned long) mm + l + 1, 0, 0) < 0) log_debug_errno(errno, "PR_SET_MM_ARG_END failed, proceeding without: %m"); } use_saved_argv: /* Fourth step: in all cases we'll also update the original argv[], so that our own code gets it right too if * it still looks here */ if (saved_argc > 0) { int i; if (saved_argv[0]) { size_t k; k = strlen(saved_argv[0]); strncpy(saved_argv[0], name, k); if (l > k) truncated = true; } for (i = 1; i < saved_argc; i++) { if (!saved_argv[i]) break; memzero(saved_argv[i], strlen(saved_argv[i])); } } return !truncated; } int is_kernel_thread(pid_t pid) { _cleanup_free_ char *line = NULL; unsigned long long flags; size_t l, i; const char *p; char *q; int r; if (IN_SET(pid, 0, 1) || pid == getpid_cached()) /* pid 1, and we ourselves certainly aren't a kernel thread */ return 0; if (!pid_is_valid(pid)) return -EINVAL; p = procfs_file_alloca(pid, "stat"); r = read_one_line_file(p, &line); if (r == -ENOENT) return -ESRCH; if (r < 0) return r; /* Skip past the comm field */ q = strrchr(line, ')'); if (!q) return -EINVAL; q++; /* Skip 6 fields to reach the flags field */ for (i = 0; i < 6; i++) { l = strspn(q, WHITESPACE); if (l < 1) return -EINVAL; q += l; l = strcspn(q, WHITESPACE); if (l < 1) return -EINVAL; q += l; } /* Skip preceding whitespace */ l = strspn(q, WHITESPACE); if (l < 1) return -EINVAL; q += l; /* Truncate the rest */ l = strcspn(q, WHITESPACE); if (l < 1) return -EINVAL; q[l] = 0; r = safe_atollu(q, &flags); if (r < 0) return r; return !!(flags & PF_KTHREAD); } int get_process_capeff(pid_t pid, char **capeff) { const char *p; int r; assert(capeff); assert(pid >= 0); p = procfs_file_alloca(pid, "status"); r = get_proc_field(p, "CapEff", WHITESPACE, capeff); if (r == -ENOENT) return -ESRCH; return r; } static int get_process_link_contents(const char *proc_file, char **name) { int r; assert(proc_file); assert(name); r = readlink_malloc(proc_file, name); if (r == -ENOENT) return -ESRCH; if (r < 0) return r; return 0; } int get_process_exe(pid_t pid, char **name) { const char *p; char *d; int r; assert(pid >= 0); p = procfs_file_alloca(pid, "exe"); r = get_process_link_contents(p, name); if (r < 0) return r; d = endswith(*name, " (deleted)"); if (d) *d = '\0'; return 0; } static int get_process_id(pid_t pid, const char *field, uid_t *uid) { _cleanup_fclose_ FILE *f = NULL; const char *p; int r; assert(field); assert(uid); if (pid < 0) return -EINVAL; p = procfs_file_alloca(pid, "status"); f = fopen(p, "re"); if (!f) { if (errno == ENOENT) return -ESRCH; return -errno; } (void) __fsetlocking(f, FSETLOCKING_BYCALLER); for (;;) { _cleanup_free_ char *line = NULL; char *l; r = read_line(f, LONG_LINE_MAX, &line); if (r < 0) return r; if (r == 0) break; l = strstrip(line); if (startswith(l, field)) { l += strlen(field); l += strspn(l, WHITESPACE); l[strcspn(l, WHITESPACE)] = 0; return parse_uid(l, uid); } } return -EIO; } int get_process_uid(pid_t pid, uid_t *uid) { if (pid == 0 || pid == getpid_cached()) { *uid = getuid(); return 0; } return get_process_id(pid, "Uid:", uid); } int get_process_gid(pid_t pid, gid_t *gid) { if (pid == 0 || pid == getpid_cached()) { *gid = getgid(); return 0; } assert_cc(sizeof(uid_t) == sizeof(gid_t)); return get_process_id(pid, "Gid:", gid); } int get_process_cwd(pid_t pid, char **cwd) { const char *p; assert(pid >= 0); p = procfs_file_alloca(pid, "cwd"); return get_process_link_contents(p, cwd); } int get_process_root(pid_t pid, char **root) { const char *p; assert(pid >= 0); p = procfs_file_alloca(pid, "root"); return get_process_link_contents(p, root); } int get_process_environ(pid_t pid, char **env) { _cleanup_fclose_ FILE *f = NULL; _cleanup_free_ char *outcome = NULL; int c; const char *p; size_t allocated = 0, sz = 0; assert(pid >= 0); assert(env); p = procfs_file_alloca(pid, "environ"); f = fopen(p, "re"); if (!f) { if (errno == ENOENT) return -ESRCH; return -errno; } (void) __fsetlocking(f, FSETLOCKING_BYCALLER); while ((c = fgetc(f)) != EOF) { if (!GREEDY_REALLOC(outcome, allocated, sz + 5)) return -ENOMEM; if (c == '\0') outcome[sz++] = '\n'; else sz += cescape_char(c, outcome + sz); } if (!outcome) { outcome = strdup(""); if (!outcome) return -ENOMEM; } else outcome[sz] = '\0'; *env = TAKE_PTR(outcome); return 0; } int get_process_ppid(pid_t pid, pid_t *_ppid) { int r; _cleanup_free_ char *line = NULL; long unsigned ppid; const char *p; assert(pid >= 0); assert(_ppid); if (pid == 0 || pid == getpid_cached()) { *_ppid = getppid(); return 0; } p = procfs_file_alloca(pid, "stat"); r = read_one_line_file(p, &line); if (r == -ENOENT) return -ESRCH; if (r < 0) return r; /* Let's skip the pid and comm fields. The latter is enclosed * in () but does not escape any () in its value, so let's * skip over it manually */ p = strrchr(line, ')'); if (!p) return -EIO; p++; if (sscanf(p, " " "%*c " /* state */ "%lu ", /* ppid */ &ppid) != 1) return -EIO; if ((long unsigned) (pid_t) ppid != ppid) return -ERANGE; *_ppid = (pid_t) ppid; return 0; } int wait_for_terminate(pid_t pid, siginfo_t *status) { siginfo_t dummy; assert(pid >= 1); if (!status) status = &dummy; for (;;) { zero(*status); if (waitid(P_PID, pid, status, WEXITED) < 0) { if (errno == EINTR) continue; return negative_errno(); } return 0; } } /* * Return values: * < 0 : wait_for_terminate() failed to get the state of the * process, the process was terminated by a signal, or * failed for an unknown reason. * >=0 : The process terminated normally, and its exit code is * returned. * * That is, success is indicated by a return value of zero, and an * error is indicated by a non-zero value. * * A warning is emitted if the process terminates abnormally, * and also if it returns non-zero unless check_exit_code is true. */ int wait_for_terminate_and_check(const char *name, pid_t pid, WaitFlags flags) { _cleanup_free_ char *buffer = NULL; siginfo_t status; int r, prio; assert(pid > 1); if (!name) { r = get_process_comm(pid, &buffer); if (r < 0) log_debug_errno(r, "Failed to acquire process name of " PID_FMT ", ignoring: %m", pid); else name = buffer; } prio = flags & WAIT_LOG_ABNORMAL ? LOG_ERR : LOG_DEBUG; r = wait_for_terminate(pid, &status); if (r < 0) return log_full_errno(prio, r, "Failed to wait for %s: %m", strna(name)); if (status.si_code == CLD_EXITED) { if (status.si_status != EXIT_SUCCESS) log_full(flags & WAIT_LOG_NON_ZERO_EXIT_STATUS ? LOG_ERR : LOG_DEBUG, "%s failed with exit status %i.", strna(name), status.si_status); else log_debug("%s succeeded.", name); return status.si_status; } else if (IN_SET(status.si_code, CLD_KILLED, CLD_DUMPED)) { log_full(prio, "%s terminated by signal %s.", strna(name), signal_to_string(status.si_status)); return -EPROTO; } log_full(prio, "%s failed due to unknown reason.", strna(name)); return -EPROTO; } /* * Return values: * * < 0 : wait_for_terminate_with_timeout() failed to get the state of the process, the process timed out, the process * was terminated by a signal, or failed for an unknown reason. * * >=0 : The process terminated normally with no failures. * * Success is indicated by a return value of zero, a timeout is indicated by ETIMEDOUT, and all other child failure * states are indicated by error is indicated by a non-zero value. * * This call assumes SIGCHLD has been blocked already, in particular before the child to wait for has been forked off * to remain entirely race-free. */ int wait_for_terminate_with_timeout(pid_t pid, usec_t timeout) { sigset_t mask; int r; usec_t until; assert_se(sigemptyset(&mask) == 0); assert_se(sigaddset(&mask, SIGCHLD) == 0); /* Drop into a sigtimewait-based timeout. Waiting for the * pid to exit. */ until = now(CLOCK_MONOTONIC) + timeout; for (;;) { usec_t n; siginfo_t status = {}; struct timespec ts; n = now(CLOCK_MONOTONIC); if (n >= until) break; r = sigtimedwait(&mask, NULL, timespec_store(&ts, until - n)) < 0 ? -errno : 0; /* Assuming we woke due to the child exiting. */ if (waitid(P_PID, pid, &status, WEXITED|WNOHANG) == 0) { if (status.si_pid == pid) { /* This is the correct child.*/ if (status.si_code == CLD_EXITED) return (status.si_status == 0) ? 0 : -EPROTO; else return -EPROTO; } } /* Not the child, check for errors and proceed appropriately */ if (r < 0) { switch (r) { case -EAGAIN: /* Timed out, child is likely hung. */ return -ETIMEDOUT; case -EINTR: /* Received a different signal and should retry */ continue; default: /* Return any unexpected errors */ return r; } } } return -EPROTO; } void sigkill_wait(pid_t pid) { assert(pid > 1); if (kill(pid, SIGKILL) > 0) (void) wait_for_terminate(pid, NULL); } void sigkill_waitp(pid_t *pid) { PROTECT_ERRNO; if (!pid) return; if (*pid <= 1) return; sigkill_wait(*pid); } void sigterm_wait(pid_t pid) { assert(pid > 1); if (kill_and_sigcont(pid, SIGTERM) > 0) (void) wait_for_terminate(pid, NULL); } int kill_and_sigcont(pid_t pid, int sig) { int r; r = kill(pid, sig) < 0 ? -errno : 0; /* If this worked, also send SIGCONT, unless we already just sent a SIGCONT, or SIGKILL was sent which isn't * affected by a process being suspended anyway. */ if (r >= 0 && !IN_SET(sig, SIGCONT, SIGKILL)) (void) kill(pid, SIGCONT); return r; } int getenv_for_pid(pid_t pid, const char *field, char **ret) { _cleanup_fclose_ FILE *f = NULL; char *value = NULL; bool done = false; const char *path; size_t l; assert(pid >= 0); assert(field); assert(ret); if (pid == 0 || pid == getpid_cached()) { const char *e; e = getenv(field); if (!e) { *ret = NULL; return 0; } value = strdup(e); if (!value) return -ENOMEM; *ret = value; return 1; } path = procfs_file_alloca(pid, "environ"); f = fopen(path, "re"); if (!f) { if (errno == ENOENT) return -ESRCH; return -errno; } (void) __fsetlocking(f, FSETLOCKING_BYCALLER); l = strlen(field); do { char line[LINE_MAX]; size_t i; for (i = 0; i < sizeof(line)-1; i++) { int c; c = getc(f); if (_unlikely_(c == EOF)) { done = true; break; } else if (c == 0) break; line[i] = c; } line[i] = 0; if (strneq(line, field, l) && line[l] == '=') { value = strdup(line + l + 1); if (!value) return -ENOMEM; *ret = value; return 1; } } while (!done); *ret = NULL; return 0; } bool pid_is_unwaited(pid_t pid) { /* Checks whether a PID is still valid at all, including a zombie */ if (pid < 0) return false; if (pid <= 1) /* If we or PID 1 would be dead and have been waited for, this code would not be running */ return true; if (pid == getpid_cached()) return true; if (kill(pid, 0) >= 0) return true; return errno != ESRCH; } bool pid_is_alive(pid_t pid) { int r; /* Checks whether a PID is still valid and not a zombie */ if (pid < 0) return false; if (pid <= 1) /* If we or PID 1 would be a zombie, this code would not be running */ return true; if (pid == getpid_cached()) return true; r = get_process_state(pid); if (IN_SET(r, -ESRCH, 'Z')) return false; return true; } int pid_from_same_root_fs(pid_t pid) { const char *root; if (pid < 0) return false; if (pid == 0 || pid == getpid_cached()) return true; root = procfs_file_alloca(pid, "root"); return files_same(root, "/proc/1/root", 0); } bool is_main_thread(void) { static thread_local int cached = 0; if (_unlikely_(cached == 0)) cached = getpid_cached() == gettid() ? 1 : -1; return cached > 0; } _noreturn_ void freeze(void) { log_close(); /* Make sure nobody waits for us on a socket anymore */ close_all_fds(NULL, 0); sync(); /* Let's not freeze right away, but keep reaping zombies. */ for (;;) { int r; siginfo_t si = {}; r = waitid(P_ALL, 0, &si, WEXITED); if (r < 0 && errno != EINTR) break; } /* waitid() failed with an unexpected error, things are really borked. Freeze now! */ for (;;) pause(); } bool oom_score_adjust_is_valid(int oa) { return oa >= OOM_SCORE_ADJ_MIN && oa <= OOM_SCORE_ADJ_MAX; } unsigned long personality_from_string(const char *p) { int architecture; if (!p) return PERSONALITY_INVALID; /* Parse a personality specifier. We use our own identifiers that indicate specific ABIs, rather than just * hints regarding the register size, since we want to keep things open for multiple locally supported ABIs for * the same register size. */ architecture = architecture_from_string(p); if (architecture < 0) return PERSONALITY_INVALID; if (architecture == native_architecture()) return PER_LINUX; #ifdef SECONDARY_ARCHITECTURE if (architecture == SECONDARY_ARCHITECTURE) return PER_LINUX32; #endif return PERSONALITY_INVALID; } const char* personality_to_string(unsigned long p) { int architecture = _ARCHITECTURE_INVALID; if (p == PER_LINUX) architecture = native_architecture(); #ifdef SECONDARY_ARCHITECTURE else if (p == PER_LINUX32) architecture = SECONDARY_ARCHITECTURE; #endif if (architecture < 0) return NULL; return architecture_to_string(architecture); } int safe_personality(unsigned long p) { int ret; /* So here's the deal, personality() is weirdly defined by glibc. In some cases it returns a failure via errno, * and in others as negative return value containing an errno-like value. Let's work around this: this is a * wrapper that uses errno if it is set, and uses the return value otherwise. And then it sets both errno and * the return value indicating the same issue, so that we are definitely on the safe side. * * See https://github.com/systemd/systemd/issues/6737 */ errno = 0; ret = personality(p); if (ret < 0) { if (errno != 0) return -errno; errno = -ret; } return ret; } int opinionated_personality(unsigned long *ret) { int current; /* Returns the current personality, or PERSONALITY_INVALID if we can't determine it. This function is a bit * opinionated though, and ignores all the finer-grained bits and exotic personalities, only distinguishing the * two most relevant personalities: PER_LINUX and PER_LINUX32. */ current = safe_personality(PERSONALITY_INVALID); if (current < 0) return current; if (((unsigned long) current & 0xffff) == PER_LINUX32) *ret = PER_LINUX32; else *ret = PER_LINUX; return 0; } void valgrind_summary_hack(void) { #if HAVE_VALGRIND_VALGRIND_H if (getpid_cached() == 1 && RUNNING_ON_VALGRIND) { pid_t pid; pid = raw_clone(SIGCHLD); if (pid < 0) log_emergency_errno(errno, "Failed to fork off valgrind helper: %m"); else if (pid == 0) exit(EXIT_SUCCESS); else { log_info("Spawned valgrind helper as PID "PID_FMT".", pid); (void) wait_for_terminate(pid, NULL); } } #endif } int pid_compare_func(const pid_t *a, const pid_t *b) { /* Suitable for usage in qsort() */ return CMP(*a, *b); } int ioprio_parse_priority(const char *s, int *ret) { int i, r; assert(s); assert(ret); r = safe_atoi(s, &i); if (r < 0) return r; if (!ioprio_priority_is_valid(i)) return -EINVAL; *ret = i; return 0; } /* The cached PID, possible values: * * == UNSET [0] → cache not initialized yet * == BUSY [-1] → some thread is initializing it at the moment * any other → the cached PID */ #define CACHED_PID_UNSET ((pid_t) 0) #define CACHED_PID_BUSY ((pid_t) -1) static pid_t cached_pid = CACHED_PID_UNSET; void reset_cached_pid(void) { /* Invoked in the child after a fork(), i.e. at the first moment the PID changed */ cached_pid = CACHED_PID_UNSET; } /* We use glibc __register_atfork() + __dso_handle directly here, as they are not included in the glibc * headers. __register_atfork() is mostly equivalent to pthread_atfork(), but doesn't require us to link against * libpthread, as it is part of glibc anyway. */ extern int __register_atfork(void (*prepare) (void), void (*parent) (void), void (*child) (void), void *dso_handle); extern void* __dso_handle __attribute__ ((__weak__)); pid_t getpid_cached(void) { static bool installed = false; pid_t current_value; /* getpid_cached() is much like getpid(), but caches the value in local memory, to avoid having to invoke a * system call each time. This restores glibc behaviour from before 2.24, when getpid() was unconditionally * cached. Starting with 2.24 getpid() started to become prohibitively expensive when used for detecting when * objects were used across fork()s. With this caching the old behaviour is somewhat restored. * * https://bugzilla.redhat.com/show_bug.cgi?id=1443976 * https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c579f48edba88380635ab98cb612030e3ed8691e */ current_value = __sync_val_compare_and_swap(&cached_pid, CACHED_PID_UNSET, CACHED_PID_BUSY); switch (current_value) { case CACHED_PID_UNSET: { /* Not initialized yet, then do so now */ pid_t new_pid; new_pid = raw_getpid(); if (!installed) { /* __register_atfork() either returns 0 or -ENOMEM, in its glibc implementation. Since it's * only half-documented (glibc doesn't document it but LSB does — though only superficially) * we'll check for errors only in the most generic fashion possible. */ if (__register_atfork(NULL, NULL, reset_cached_pid, __dso_handle) != 0) { /* OOM? Let's try again later */ cached_pid = CACHED_PID_UNSET; return new_pid; } installed = true; } cached_pid = new_pid; return new_pid; } case CACHED_PID_BUSY: /* Somebody else is currently initializing */ return raw_getpid(); default: /* Properly initialized */ return current_value; } } int must_be_root(void) { if (geteuid() == 0) return 0; log_error("Need to be root."); return -EPERM; } int safe_fork_full( const char *name, const int except_fds[], size_t n_except_fds, ForkFlags flags, pid_t *ret_pid) { pid_t original_pid, pid; sigset_t saved_ss, ss; bool block_signals = false; int prio, r; /* A wrapper around fork(), that does a couple of important initializations in addition to mere forking. Always * returns the child's PID in *ret_pid. Returns == 0 in the child, and > 0 in the parent. */ prio = flags & FORK_LOG ? LOG_ERR : LOG_DEBUG; original_pid = getpid_cached(); if (flags & (FORK_RESET_SIGNALS|FORK_DEATHSIG)) { /* We temporarily block all signals, so that the new child has them blocked initially. This way, we can * be sure that SIGTERMs are not lost we might send to the child. */ if (sigfillset(&ss) < 0) return log_full_errno(prio, errno, "Failed to reset signal set: %m"); block_signals = true; } else if (flags & FORK_WAIT) { /* Let's block SIGCHLD at least, so that we can safely watch for the child process */ if (sigemptyset(&ss) < 0) return log_full_errno(prio, errno, "Failed to clear signal set: %m"); if (sigaddset(&ss, SIGCHLD) < 0) return log_full_errno(prio, errno, "Failed to add SIGCHLD to signal set: %m"); block_signals = true; } if (block_signals) if (sigprocmask(SIG_SETMASK, &ss, &saved_ss) < 0) return log_full_errno(prio, errno, "Failed to set signal mask: %m"); if (flags & FORK_NEW_MOUNTNS) pid = raw_clone(SIGCHLD|CLONE_NEWNS); else pid = fork(); if (pid < 0) { r = -errno; if (block_signals) /* undo what we did above */ (void) sigprocmask(SIG_SETMASK, &saved_ss, NULL); return log_full_errno(prio, r, "Failed to fork: %m"); } if (pid > 0) { /* We are in the parent process */ log_debug("Successfully forked off '%s' as PID " PID_FMT ".", strna(name), pid); if (flags & FORK_WAIT) { r = wait_for_terminate_and_check(name, pid, (flags & FORK_LOG ? WAIT_LOG : 0)); if (r < 0) return r; if (r != EXIT_SUCCESS) /* exit status > 0 should be treated as failure, too */ return -EPROTO; } if (block_signals) /* undo what we did above */ (void) sigprocmask(SIG_SETMASK, &saved_ss, NULL); if (ret_pid) *ret_pid = pid; return 1; } /* We are in the child process */ if (flags & FORK_REOPEN_LOG) { /* Close the logs if requested, before we log anything. And make sure we reopen it if needed. */ log_close(); log_set_open_when_needed(true); } if (name) { r = rename_process(name); if (r < 0) log_full_errno(flags & FORK_LOG ? LOG_WARNING : LOG_DEBUG, r, "Failed to rename process, ignoring: %m"); } if (flags & FORK_DEATHSIG) if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0) { log_full_errno(prio, errno, "Failed to set death signal: %m"); _exit(EXIT_FAILURE); } if (flags & FORK_RESET_SIGNALS) { r = reset_all_signal_handlers(); if (r < 0) { log_full_errno(prio, r, "Failed to reset signal handlers: %m"); _exit(EXIT_FAILURE); } /* This implicitly undoes the signal mask stuff we did before the fork()ing above */ r = reset_signal_mask(); if (r < 0) { log_full_errno(prio, r, "Failed to reset signal mask: %m"); _exit(EXIT_FAILURE); } } else if (block_signals) { /* undo what we did above */ if (sigprocmask(SIG_SETMASK, &saved_ss, NULL) < 0) { log_full_errno(prio, errno, "Failed to restore signal mask: %m"); _exit(EXIT_FAILURE); } } if (flags & FORK_DEATHSIG) { pid_t ppid; /* Let's see if the parent PID is still the one we started from? If not, then the parent * already died by the time we set PR_SET_PDEATHSIG, hence let's emulate the effect */ ppid = getppid(); if (ppid == 0) /* Parent is in a differn't PID namespace. */; else if (ppid != original_pid) { log_debug("Parent died early, raising SIGTERM."); (void) raise(SIGTERM); _exit(EXIT_FAILURE); } } if (FLAGS_SET(flags, FORK_NEW_MOUNTNS | FORK_MOUNTNS_SLAVE)) { /* Optionally, make sure we never propagate mounts to the host. */ if (mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) < 0) { log_full_errno(prio, errno, "Failed to remount root directory as MS_SLAVE: %m"); _exit(EXIT_FAILURE); } } if (flags & FORK_CLOSE_ALL_FDS) { /* Close the logs here in case it got reopened above, as close_all_fds() would close them for us */ log_close(); r = close_all_fds(except_fds, n_except_fds); if (r < 0) { log_full_errno(prio, r, "Failed to close all file descriptors: %m"); _exit(EXIT_FAILURE); } } /* When we were asked to reopen the logs, do so again now */ if (flags & FORK_REOPEN_LOG) { log_open(); log_set_open_when_needed(false); } if (flags & FORK_NULL_STDIO) { r = make_null_stdio(); if (r < 0) { log_full_errno(prio, r, "Failed to connect stdin/stdout to /dev/null: %m"); _exit(EXIT_FAILURE); } } if (ret_pid) *ret_pid = getpid_cached(); return 0; } int namespace_fork( const char *outer_name, const char *inner_name, const int except_fds[], size_t n_except_fds, ForkFlags flags, int pidns_fd, int mntns_fd, int netns_fd, int userns_fd, int root_fd, pid_t *ret_pid) { int r; /* This is much like safe_fork(), but forks twice, and joins the specified namespaces in the middle * process. This ensures that we are fully a member of the destination namespace, with pidns an all, so that * /proc/self/fd works correctly. */ r = safe_fork_full(outer_name, except_fds, n_except_fds, (flags|FORK_DEATHSIG) & ~(FORK_REOPEN_LOG|FORK_NEW_MOUNTNS|FORK_MOUNTNS_SLAVE), ret_pid); if (r < 0) return r; if (r == 0) { pid_t pid; /* Child */ r = namespace_enter(pidns_fd, mntns_fd, netns_fd, userns_fd, root_fd); if (r < 0) { log_full_errno(FLAGS_SET(flags, FORK_LOG) ? LOG_ERR : LOG_DEBUG, r, "Failed to join namespace: %m"); _exit(EXIT_FAILURE); } /* We mask a few flags here that either make no sense for the grandchild, or that we don't have to do again */ r = safe_fork_full(inner_name, except_fds, n_except_fds, flags & ~(FORK_WAIT|FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_NULL_STDIO), &pid); if (r < 0) _exit(EXIT_FAILURE); if (r == 0) { /* Child */ if (ret_pid) *ret_pid = pid; return 0; } r = wait_for_terminate_and_check(inner_name, pid, FLAGS_SET(flags, FORK_LOG) ? WAIT_LOG : 0); if (r < 0) _exit(EXIT_FAILURE); _exit(r); } return 1; } int fork_agent(const char *name, const int except[], size_t n_except, pid_t *ret_pid, const char *path, ...) { bool stdout_is_tty, stderr_is_tty; size_t n, i; va_list ap; char **l; int r; assert(path); /* Spawns a temporary TTY agent, making sure it goes away when we go away */ r = safe_fork_full(name, except, n_except, FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_CLOSE_ALL_FDS, ret_pid); if (r < 0) return r; if (r > 0) return 0; /* In the child: */ stdout_is_tty = isatty(STDOUT_FILENO); stderr_is_tty = isatty(STDERR_FILENO); if (!stdout_is_tty || !stderr_is_tty) { int fd; /* Detach from stdout/stderr. and reopen * /dev/tty for them. This is important to * ensure that when systemctl is started via * popen() or a similar call that expects to * read EOF we actually do generate EOF and * not delay this indefinitely by because we * keep an unused copy of stdin around. */ fd = open("/dev/tty", O_WRONLY); if (fd < 0) { log_error_errno(errno, "Failed to open /dev/tty: %m"); _exit(EXIT_FAILURE); } if (!stdout_is_tty && dup2(fd, STDOUT_FILENO) < 0) { log_error_errno(errno, "Failed to dup2 /dev/tty: %m"); _exit(EXIT_FAILURE); } if (!stderr_is_tty && dup2(fd, STDERR_FILENO) < 0) { log_error_errno(errno, "Failed to dup2 /dev/tty: %m"); _exit(EXIT_FAILURE); } safe_close_above_stdio(fd); } /* Count arguments */ va_start(ap, path); for (n = 0; va_arg(ap, char*); n++) ; va_end(ap); /* Allocate strv */ l = newa(char*, n + 1); /* Fill in arguments */ va_start(ap, path); for (i = 0; i <= n; i++) l[i] = va_arg(ap, char*); va_end(ap); execv(path, l); _exit(EXIT_FAILURE); } int set_oom_score_adjust(int value) { char t[DECIMAL_STR_MAX(int)]; sprintf(t, "%i", value); return write_string_file("/proc/self/oom_score_adj", t, WRITE_STRING_FILE_VERIFY_ON_FAILURE|WRITE_STRING_FILE_DISABLE_BUFFER); } static const char *const ioprio_class_table[] = { [IOPRIO_CLASS_NONE] = "none", [IOPRIO_CLASS_RT] = "realtime", [IOPRIO_CLASS_BE] = "best-effort", [IOPRIO_CLASS_IDLE] = "idle" }; DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(ioprio_class, int, IOPRIO_N_CLASSES); static const char *const sigchld_code_table[] = { [CLD_EXITED] = "exited", [CLD_KILLED] = "killed", [CLD_DUMPED] = "dumped", [CLD_TRAPPED] = "trapped", [CLD_STOPPED] = "stopped", [CLD_CONTINUED] = "continued", }; DEFINE_STRING_TABLE_LOOKUP(sigchld_code, int); static const char* const sched_policy_table[] = { [SCHED_OTHER] = "other", [SCHED_BATCH] = "batch", [SCHED_IDLE] = "idle", [SCHED_FIFO] = "fifo", [SCHED_RR] = "rr" }; DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(sched_policy, int, INT_MAX);