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-rw-r--r--src/shared/killall.c283
1 files changed, 283 insertions, 0 deletions
diff --git a/src/shared/killall.c b/src/shared/killall.c
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index 0000000..1c98972
--- /dev/null
+++ b/src/shared/killall.c
@@ -0,0 +1,283 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/***
+ Copyright © 2010 ProFUSION embedded systems
+***/
+
+#include <errno.h>
+#include <signal.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "def.h"
+#include "dirent-util.h"
+#include "fd-util.h"
+#include "format-util.h"
+#include "killall.h"
+#include "parse-util.h"
+#include "process-util.h"
+#include "set.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "terminal-util.h"
+#include "util.h"
+
+static bool ignore_proc(pid_t pid, bool warn_rootfs) {
+ _cleanup_fclose_ FILE *f = NULL;
+ const char *p;
+ char c = 0;
+ uid_t uid;
+ int r;
+
+ /* We are PID 1, let's not commit suicide */
+ if (pid <= 1)
+ return true;
+
+ /* Ignore kernel threads */
+ r = is_kernel_thread(pid);
+ if (r != 0)
+ return true; /* also ignore processes where we can't determine this */
+
+ r = get_process_uid(pid, &uid);
+ if (r < 0)
+ return true; /* not really, but better safe than sorry */
+
+ /* Non-root processes otherwise are always subject to be killed */
+ if (uid != 0)
+ return false;
+
+ p = procfs_file_alloca(pid, "cmdline");
+ f = fopen(p, "re");
+ if (!f)
+ return true; /* not really, but has the desired effect */
+
+ /* Try to read the first character of the command line. If the cmdline is empty (which might be the case for
+ * kernel threads but potentially also other stuff), this line won't do anything, but we don't care much, as
+ * actual kernel threads are already filtered out above. */
+ (void) fread(&c, 1, 1, f);
+
+ /* Processes with argv[0][0] = '@' we ignore from the killing spree.
+ *
+ * https://systemd.io/ROOT_STORAGE_DAEMONS */
+ if (c != '@')
+ return false;
+
+ if (warn_rootfs &&
+ pid_from_same_root_fs(pid) > 0) {
+
+ _cleanup_free_ char *comm = NULL;
+
+ (void) get_process_comm(pid, &comm);
+
+ log_notice("Process " PID_FMT " (%s) has been marked to be excluded from killing. It is "
+ "running from the root file system, and thus likely to block re-mounting of the "
+ "root file system to read-only. Please consider moving it into an initrd file "
+ "system instead.", pid, strna(comm));
+ }
+
+ return true;
+}
+
+static void log_children_no_yet_killed(Set *pids) {
+ _cleanup_free_ char *lst_child = NULL;
+ void *p;
+ int r;
+
+ SET_FOREACH(p, pids) {
+ _cleanup_free_ char *s = NULL;
+
+ if (get_process_comm(PTR_TO_PID(p), &s) >= 0)
+ r = strextendf(&lst_child, ", " PID_FMT " (%s)", PTR_TO_PID(p), s);
+ else
+ r = strextendf(&lst_child, ", " PID_FMT, PTR_TO_PID(p));
+ if (r < 0)
+ return (void) log_oom();
+ }
+
+ if (isempty(lst_child))
+ return;
+
+ log_warning("Waiting for process: %s", lst_child + 2);
+}
+
+static int wait_for_children(Set *pids, sigset_t *mask, usec_t timeout) {
+ usec_t until, date_log_child, n;
+
+ assert(mask);
+
+ /* Return the number of children remaining in the pids set: That correspond to the number
+ * of processes still "alive" after the timeout */
+
+ if (set_isempty(pids))
+ return 0;
+
+ n = now(CLOCK_MONOTONIC);
+ until = usec_add(n, timeout);
+ date_log_child = usec_add(n, 10u * USEC_PER_SEC);
+ if (date_log_child > until)
+ date_log_child = usec_add(n, timeout / 2u);
+
+ for (;;) {
+ struct timespec ts;
+ int k;
+ void *p;
+
+ /* First, let the kernel inform us about killed
+ * children. Most processes will probably be our
+ * children, but some are not (might be our
+ * grandchildren instead...). */
+ for (;;) {
+ pid_t pid;
+
+ pid = waitpid(-1, NULL, WNOHANG);
+ if (pid == 0)
+ break;
+ if (pid < 0) {
+ if (errno == ECHILD)
+ break;
+
+ return log_error_errno(errno, "waitpid() failed: %m");
+ }
+
+ (void) set_remove(pids, PID_TO_PTR(pid));
+ }
+
+ /* Now explicitly check who might be remaining, who
+ * might not be our child. */
+ SET_FOREACH(p, pids) {
+
+ /* kill(pid, 0) sends no signal, but it tells
+ * us whether the process still exists. */
+ if (kill(PTR_TO_PID(p), 0) == 0)
+ continue;
+
+ if (errno != ESRCH)
+ continue;
+
+ set_remove(pids, p);
+ }
+
+ if (set_isempty(pids))
+ return 0;
+
+ n = now(CLOCK_MONOTONIC);
+ if (date_log_child > 0 && n >= date_log_child) {
+ log_children_no_yet_killed(pids);
+ /* Log the children not yet killed only once */
+ date_log_child = 0;
+ }
+
+ if (n >= until)
+ return set_size(pids);
+
+ if (date_log_child > 0)
+ timespec_store(&ts, MIN(until - n, date_log_child - n));
+ else
+ timespec_store(&ts, until - n);
+
+ k = sigtimedwait(mask, NULL, &ts);
+ if (k != SIGCHLD) {
+
+ if (k < 0 && errno != EAGAIN)
+ return log_error_errno(errno, "sigtimedwait() failed: %m");
+
+ if (k >= 0)
+ log_warning("sigtimedwait() returned unexpected signal.");
+ }
+ }
+}
+
+static int killall(int sig, Set *pids, bool send_sighup) {
+ _cleanup_closedir_ DIR *dir = NULL;
+ int n_killed = 0;
+
+ /* Send the specified signal to all remaining processes, if not excluded by ignore_proc().
+ * Returns the number of processes to which the specified signal was sent */
+
+ dir = opendir("/proc");
+ if (!dir)
+ return log_warning_errno(errno, "opendir(/proc) failed: %m");
+
+ FOREACH_DIRENT_ALL(de, dir, break) {
+ pid_t pid;
+ int r;
+
+ if (!IN_SET(de->d_type, DT_DIR, DT_UNKNOWN))
+ continue;
+
+ if (parse_pid(de->d_name, &pid) < 0)
+ continue;
+
+ if (ignore_proc(pid, sig == SIGKILL && !in_initrd()))
+ continue;
+
+ if (sig == SIGKILL) {
+ _cleanup_free_ char *s = NULL;
+
+ (void) get_process_comm(pid, &s);
+ log_notice("Sending SIGKILL to PID "PID_FMT" (%s).", pid, strna(s));
+ }
+
+ if (kill(pid, sig) >= 0) {
+ n_killed++;
+ if (pids) {
+ r = set_put(pids, PID_TO_PTR(pid));
+ if (r < 0)
+ log_oom();
+ }
+ } else if (errno != ENOENT)
+ log_warning_errno(errno, "Could not kill %d: %m", pid);
+
+ if (send_sighup) {
+ /* Optionally, also send a SIGHUP signal, but
+ only if the process has a controlling
+ tty. This is useful to allow handling of
+ shells which ignore SIGTERM but react to
+ SIGHUP. We do not send this to processes that
+ have no controlling TTY since we don't want to
+ trigger reloads of daemon processes. Also we
+ make sure to only send this after SIGTERM so
+ that SIGTERM is always first in the queue. */
+
+ if (get_ctty_devnr(pid, NULL) >= 0)
+ /* it's OK if the process is gone, just ignore the result */
+ (void) kill(pid, SIGHUP);
+ }
+ }
+
+ return n_killed;
+}
+
+int broadcast_signal(int sig, bool wait_for_exit, bool send_sighup, usec_t timeout) {
+ int n_children_left;
+ sigset_t mask, oldmask;
+ _cleanup_set_free_ Set *pids = NULL;
+
+ /* Send the specified signal to all remaining processes, if not excluded by ignore_proc().
+ * Return:
+ * - The number of processes still "alive" after the timeout (that should have been killed)
+ * if the function needs to wait for the end of the processes (wait_for_exit).
+ * - Otherwise, the number of processes to which the specified signal was sent */
+
+ if (wait_for_exit)
+ pids = set_new(NULL);
+
+ assert_se(sigemptyset(&mask) == 0);
+ assert_se(sigaddset(&mask, SIGCHLD) == 0);
+ assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
+
+ if (kill(-1, SIGSTOP) < 0 && errno != ESRCH)
+ log_warning_errno(errno, "kill(-1, SIGSTOP) failed: %m");
+
+ n_children_left = killall(sig, pids, send_sighup);
+
+ if (kill(-1, SIGCONT) < 0 && errno != ESRCH)
+ log_warning_errno(errno, "kill(-1, SIGCONT) failed: %m");
+
+ if (wait_for_exit && n_children_left > 0)
+ n_children_left = wait_for_children(pids, &mask, timeout);
+
+ assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
+
+ return n_children_left;
+}