diff options
Diffstat (limited to 'src/shared/killall.c')
| -rw-r--r-- | src/shared/killall.c | 283 |
1 files changed, 283 insertions, 0 deletions
diff --git a/src/shared/killall.c b/src/shared/killall.c new file mode 100644 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; +} |