234 lines
7.4 KiB
C
234 lines
7.4 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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/***
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This file is part of systemd.
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Copyright 2010 ProFUSION embedded systems
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***/
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#include <errno.h>
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#include <signal.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include "alloc-util.h"
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#include "def.h"
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#include "dirent-util.h"
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#include "fd-util.h"
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#include "format-util.h"
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#include "killall.h"
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#include "parse-util.h"
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#include "process-util.h"
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#include "set.h"
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#include "string-util.h"
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#include "terminal-util.h"
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#include "util.h"
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static bool ignore_proc(pid_t pid, bool warn_rootfs) {
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_cleanup_fclose_ FILE *f = NULL;
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char c;
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const char *p;
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size_t count;
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uid_t uid;
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int r;
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/* We are PID 1, let's not commit suicide */
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if (pid == 1)
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return true;
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r = get_process_uid(pid, &uid);
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if (r < 0)
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return true; /* not really, but better safe than sorry */
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/* Non-root processes otherwise are always subject to be killed */
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if (uid != 0)
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return false;
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p = procfs_file_alloca(pid, "cmdline");
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f = fopen(p, "re");
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if (!f)
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return true; /* not really, but has the desired effect */
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count = fread(&c, 1, 1, f);
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/* Kernel threads have an empty cmdline */
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if (count <= 0)
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return true;
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/* Processes with argv[0][0] = '@' we ignore from the killing spree.
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*
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* http://www.freedesktop.org/wiki/Software/systemd/RootStorageDaemons */
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if (c != '@')
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return false;
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if (warn_rootfs &&
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pid_from_same_root_fs(pid) == 0) {
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_cleanup_free_ char *comm = NULL;
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get_process_comm(pid, &comm);
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log_notice("Process " PID_FMT " (%s) has been marked to be excluded from killing. It is "
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"running from the root file system, and thus likely to block re-mounting of the "
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"root file system to read-only. Please consider moving it into an initrd file "
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"system instead.", pid, strna(comm));
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}
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return true;
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}
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static void wait_for_children(Set *pids, sigset_t *mask, usec_t timeout) {
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usec_t until;
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assert(mask);
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if (set_isempty(pids))
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return;
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until = now(CLOCK_MONOTONIC) + timeout;
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for (;;) {
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struct timespec ts;
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int k;
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usec_t n;
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void *p;
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Iterator i;
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/* First, let the kernel inform us about killed
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* children. Most processes will probably be our
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* children, but some are not (might be our
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* grandchildren instead...). */
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for (;;) {
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pid_t pid;
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pid = waitpid(-1, NULL, WNOHANG);
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if (pid == 0)
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break;
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if (pid < 0) {
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if (errno == ECHILD)
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break;
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log_error_errno(errno, "waitpid() failed: %m");
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return;
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}
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(void) set_remove(pids, PID_TO_PTR(pid));
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}
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/* Now explicitly check who might be remaining, who
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* might not be our child. */
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SET_FOREACH(p, pids, i) {
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/* kill(pid, 0) sends no signal, but it tells
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* us whether the process still exists. */
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if (kill(PTR_TO_PID(p), 0) == 0)
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continue;
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if (errno != ESRCH)
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continue;
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set_remove(pids, p);
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}
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if (set_isempty(pids))
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return;
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n = now(CLOCK_MONOTONIC);
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if (n >= until)
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return;
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timespec_store(&ts, until - n);
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k = sigtimedwait(mask, NULL, &ts);
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if (k != SIGCHLD) {
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if (k < 0 && errno != EAGAIN) {
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log_error_errno(errno, "sigtimedwait() failed: %m");
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return;
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}
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if (k >= 0)
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log_warning("sigtimedwait() returned unexpected signal.");
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}
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}
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}
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static int killall(int sig, Set *pids, bool send_sighup) {
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_cleanup_closedir_ DIR *dir = NULL;
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struct dirent *d;
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dir = opendir("/proc");
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if (!dir)
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return -errno;
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FOREACH_DIRENT_ALL(d, dir, break) {
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pid_t pid;
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int r;
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if (!IN_SET(d->d_type, DT_DIR, DT_UNKNOWN))
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continue;
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if (parse_pid(d->d_name, &pid) < 0)
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continue;
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if (ignore_proc(pid, sig == SIGKILL && !in_initrd()))
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continue;
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if (sig == SIGKILL) {
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_cleanup_free_ char *s = NULL;
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get_process_comm(pid, &s);
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log_notice("Sending SIGKILL to PID "PID_FMT" (%s).", pid, strna(s));
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}
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if (kill(pid, sig) >= 0) {
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if (pids) {
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r = set_put(pids, PID_TO_PTR(pid));
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if (r < 0)
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log_oom();
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}
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} else if (errno != ENOENT)
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log_warning_errno(errno, "Could not kill %d: %m", pid);
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if (send_sighup) {
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/* Optionally, also send a SIGHUP signal, but
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only if the process has a controlling
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tty. This is useful to allow handling of
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shells which ignore SIGTERM but react to
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SIGHUP. We do not send this to processes that
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have no controlling TTY since we don't want to
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trigger reloads of daemon processes. Also we
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make sure to only send this after SIGTERM so
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that SIGTERM is always first in the queue. */
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if (get_ctty_devnr(pid, NULL) >= 0)
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/* it's OK if the process is gone, just ignore the result */
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(void) kill(pid, SIGHUP);
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}
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}
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return set_size(pids);
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}
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void broadcast_signal(int sig, bool wait_for_exit, bool send_sighup, usec_t timeout) {
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sigset_t mask, oldmask;
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_cleanup_set_free_ Set *pids = NULL;
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if (wait_for_exit)
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pids = set_new(NULL);
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assert_se(sigemptyset(&mask) == 0);
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assert_se(sigaddset(&mask, SIGCHLD) == 0);
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assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
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if (kill(-1, SIGSTOP) < 0 && errno != ESRCH)
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log_warning_errno(errno, "kill(-1, SIGSTOP) failed: %m");
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killall(sig, pids, send_sighup);
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if (kill(-1, SIGCONT) < 0 && errno != ESRCH)
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log_warning_errno(errno, "kill(-1, SIGCONT) failed: %m");
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if (wait_for_exit)
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wait_for_children(pids, &mask, timeout);
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assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
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}
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