src/core/killall.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 ProFUSION embedded systems
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  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   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <sys/wait.h>
  23 #include <signal.h>
  24 #include <errno.h>
  25 #include <unistd.h>
  26
  27 #include "util.h"
  28 #include "def.h"
  29 #include "killall.h"
  30 #include "set.h"
  31
  32 #define TIMEOUT_USEC (10 * USEC_PER_SEC)
  33
  34 static bool ignore_proc(pid_t pid) {
  35         _cleanup_fclose_ FILE *f = NULL;
  36         char c, *p;
  37         size_t count;
  38         uid_t uid;
  39         int r;
  40
  41         /* We are PID 1, let's not commit suicide */
  42         if (pid == 1)
  43                 return true;
  44
  45         r = get_process_uid(pid, &uid);
  46         if (r < 0)
  47                 return true; /* not really, but better safe than sorry */
  48
  49         /* Non-root processes otherwise are always subject to be killed */
  50         if (uid != 0)
  51                 return false;
  52
  53         p = procfs_file_alloca(pid, "cmdline");
  54         f = fopen(p, "re");
  55         if (!f)
  56                 return true; /* not really, but has the desired effect */
  57
  58         count = fread(&c, 1, 1, f);
  59
  60         /* Kernel threads have an empty cmdline */
  61         if (count <= 0)
  62                 return true;
  63
  64         /* Processes with argv[0][0] = '@' we ignore from the killing
  65          * spree.
  66          *
  67          * http://www.freedesktop.org/wiki/Software/systemd/RootStorageDaemons */
  68         if (count == 1 && c == '@')
  69                 return true;
  70
  71         return false;
  72 }
  73
  74 static void wait_for_children(Set *pids, sigset_t *mask) {
  75         usec_t until;
  76
  77         assert(mask);
  78
  79         if (set_isempty(pids))
  80                 return;
  81
  82         until = now(CLOCK_MONOTONIC) + TIMEOUT_USEC;
  83         for (;;) {
  84                 struct timespec ts;
  85                 int k;
  86                 usec_t n;
  87                 void *p;
  88                 Iterator i;
  89
  90                 /* First, let the kernel inform us about killed
  91                  * children. Most processes will probably be our
  92                  * children, but some are not (might be our
  93                  * grandchildren instead...). */
  94                 for (;;) {
  95                         pid_t pid;
  96
  97                         pid = waitpid(-1, NULL, WNOHANG);
  98                         if (pid == 0)
  99                                 break;
 100                         if (pid < 0) {
 101                                 if (errno == ECHILD)
 102                                         break;
 103
 104                                 log_error("waitpid() failed: %m");
 105                                 return;
 106                         }
 107
 108                         set_remove(pids, ULONG_TO_PTR(pid));
 109                 }
 110
 111                 /* Now explicitly check who might be remaining, who
 112                  * might not be our child. */
 113                 SET_FOREACH(p, pids, i) {
 114
 115                         /* We misuse getpgid as a check whether a
 116                          * process still exists. */
 117                         if (getpgid((pid_t) PTR_TO_ULONG(p)) >= 0)
 118                                 continue;
 119
 120                         if (errno != ESRCH)
 121                                 continue;
 122
 123                         set_remove(pids, p);
 124                 }
 125
 126                 if (set_isempty(pids))
 127                         return;
 128
 129                 n = now(CLOCK_MONOTONIC);
 130                 if (n >= until)
 131                         return;
 132
 133                 timespec_store(&ts, until - n);
 134                 k = sigtimedwait(mask, NULL, &ts);
 135                 if (k != SIGCHLD) {
 136
 137                         if (k < 0 && errno != EAGAIN) {
 138                                 log_error("sigtimedwait() failed: %m");
 139                                 return;
 140                         }
 141
 142                         if (k >= 0)
 143                                 log_warning("sigtimedwait() returned unexpected signal.");
 144                 }
 145         }
 146 }
 147
 148 static int killall(int sig, Set *pids, bool send_sighup) {
 149         _cleanup_closedir_ DIR *dir = NULL;
 150         struct dirent *d;
 151
 152         dir = opendir("/proc");
 153         if (!dir)
 154                 return -errno;
 155
 156         while ((d = readdir(dir))) {
 157                 pid_t pid;
 158
 159                 if (d->d_type != DT_DIR &&
 160                     d->d_type != DT_UNKNOWN)
 161                         continue;
 162
 163                 if (parse_pid(d->d_name, &pid) < 0)
 164                         continue;
 165
 166                 if (ignore_proc(pid))
 167                         continue;
 168
 169                 if (sig == SIGKILL) {
 170                         _cleanup_free_ char *s;
 171
 172                         get_process_comm(pid, &s);
 173                         log_notice("Sending SIGKILL to PID "PID_FMT" (%s).", pid, strna(s));
 174                 }
 175
 176                 if (kill(pid, sig) >= 0) {
 177                         if (pids)
 178                                 set_put(pids, ULONG_TO_PTR(pid));
 179                 } else if (errno != ENOENT)
 180                         log_warning("Could not kill %d: %m", pid);
 181
 182                 if (send_sighup) {
 183                         /* Optionally, also send a SIGHUP signal, but
 184                         only if the process has a controlling
 185                         tty. This is useful to allow handling of
 186                         shells which ignore SIGTERM but react to
 187                         SIGHUP. We do not send this to processes that
 188                         have no controlling TTY since we don't want to
 189                         trigger reloads of daemon processes. Also we
 190                         make sure to only send this after SIGTERM so
 191                         that SIGTERM is always first in the queue. */
 192
 193
 194                         if (get_ctty_devnr(pid, NULL) >= 0)
 195                                 kill(pid, SIGHUP);
 196                 }
 197         }
 198
 199         return set_size(pids);
 200 }
 201
 202 void broadcast_signal(int sig, bool wait_for_exit, bool send_sighup) {
 203         sigset_t mask, oldmask;
 204         Set *pids = NULL;
 205
 206         if (wait_for_exit)
 207                 pids = set_new(trivial_hash_func, trivial_compare_func);
 208
 209         assert_se(sigemptyset(&mask) == 0);
 210         assert_se(sigaddset(&mask, SIGCHLD) == 0);
 211         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
 212
 213         if (kill(-1, SIGSTOP) < 0 && errno != ESRCH)
 214                 log_warning("kill(-1, SIGSTOP) failed: %m");
 215
 216         killall(sig, pids, send_sighup);
 217
 218         if (kill(-1, SIGCONT) < 0 && errno != ESRCH)
 219                 log_warning("kill(-1, SIGCONT) failed: %m");
 220
 221         if (wait_for_exit)
 222                 wait_for_children(pids, &mask);
 223
 224         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 225
 226         set_free(pids);
 227 }