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