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 <errno.h>
  23 #include <signal.h>
  24 #include <sys/wait.h>
  25 #include <unistd.h>
  26
  27 #include "fd-util.h"
  28 #include "formats-util.h"
  29 #include "killall.h"
  30 #include "process-util.h"
  31 #include "set.h"
  32 #include "string-util.h"
  33 #include "terminal-util.h"
  34 #include "util.h"
  35
  36 #define TIMEOUT_USEC (10 * USEC_PER_SEC)
  37
  38 static bool ignore_proc(pid_t pid) {
  39         _cleanup_fclose_ FILE *f = NULL;
  40         char c;
  41         const char *p;
  42         size_t count;
  43         uid_t uid;
  44         int r;
  45
  46         /* We are PID 1, let's not commit suicide */
  47         if (pid == 1)
  48                 return true;
  49
  50         r = get_process_uid(pid, &uid);
  51         if (r < 0)
  52                 return true; /* not really, but better safe than sorry */
  53
  54         /* Non-root processes otherwise are always subject to be killed */
  55         if (uid != 0)
  56                 return false;
  57
  58         p = procfs_file_alloca(pid, "cmdline");
  59         f = fopen(p, "re");
  60         if (!f)
  61                 return true; /* not really, but has the desired effect */
  62
  63         count = fread(&c, 1, 1, f);
  64
  65         /* Kernel threads have an empty cmdline */
  66         if (count <= 0)
  67                 return true;
  68
  69         /* Processes with argv[0][0] = '@' we ignore from the killing
  70          * spree.
  71          *
  72          * http://www.freedesktop.org/wiki/Software/systemd/RootStorageDaemons */
  73         if (count == 1 && c == '@')
  74                 return true;
  75
  76         return false;
  77 }
  78
  79 static void wait_for_children(Set *pids, sigset_t *mask) {
  80         usec_t until;
  81
  82         assert(mask);
  83
  84         if (set_isempty(pids))
  85                 return;
  86
  87         until = now(CLOCK_MONOTONIC) + TIMEOUT_USEC;
  88         for (;;) {
  89                 struct timespec ts;
  90                 int k;
  91                 usec_t n;
  92                 void *p;
  93                 Iterator i;
  94
  95                 /* First, let the kernel inform us about killed
  96                  * children. Most processes will probably be our
  97                  * children, but some are not (might be our
  98                  * grandchildren instead...). */
  99                 for (;;) {
 100                         pid_t pid;
 101
 102                         pid = waitpid(-1, NULL, WNOHANG);
 103                         if (pid == 0)
 104                                 break;
 105                         if (pid < 0) {
 106                                 if (errno == ECHILD)
 107                                         break;
 108
 109                                 log_error_errno(errno, "waitpid() failed: %m");
 110                                 return;
 111                         }
 112
 113                         (void) set_remove(pids, PID_TO_PTR(pid));
 114                 }
 115
 116                 /* Now explicitly check who might be remaining, who
 117                  * might not be our child. */
 118                 SET_FOREACH(p, pids, i) {
 119
 120                         /* We misuse getpgid as a check whether a
 121                          * process still exists. */
 122                         if (getpgid(PTR_TO_PID(p)) >= 0)
 123                                 continue;
 124
 125                         if (errno != ESRCH)
 126                                 continue;
 127
 128                         set_remove(pids, p);
 129                 }
 130
 131                 if (set_isempty(pids))
 132                         return;
 133
 134                 n = now(CLOCK_MONOTONIC);
 135                 if (n >= until)
 136                         return;
 137
 138                 timespec_store(&ts, until - n);
 139                 k = sigtimedwait(mask, NULL, &ts);
 140                 if (k != SIGCHLD) {
 141
 142                         if (k < 0 && errno != EAGAIN) {
 143                                 log_error_errno(errno, "sigtimedwait() failed: %m");
 144                                 return;
 145                         }
 146
 147                         if (k >= 0)
 148                                 log_warning("sigtimedwait() returned unexpected signal.");
 149                 }
 150         }
 151 }
 152
 153 static int killall(int sig, Set *pids, bool send_sighup) {
 154         _cleanup_closedir_ DIR *dir = NULL;
 155         struct dirent *d;
 156
 157         dir = opendir("/proc");
 158         if (!dir)
 159                 return -errno;
 160
 161         while ((d = readdir(dir))) {
 162                 pid_t pid;
 163                 int r;
 164
 165                 if (d->d_type != DT_DIR &&
 166                     d->d_type != DT_UNKNOWN)
 167                         continue;
 168
 169                 if (parse_pid(d->d_name, &pid) < 0)
 170                         continue;
 171
 172                 if (ignore_proc(pid))
 173                         continue;
 174
 175                 if (sig == SIGKILL) {
 176                         _cleanup_free_ char *s = NULL;
 177
 178                         get_process_comm(pid, &s);
 179                         log_notice("Sending SIGKILL to PID "PID_FMT" (%s).", pid, strna(s));
 180                 }
 181
 182                 if (kill(pid, sig) >= 0) {
 183                         if (pids) {
 184                                 r = set_put(pids, PID_TO_PTR(pid));
 185                                 if (r < 0)
 186                                         log_oom();
 187                         }
 188                 } else if (errno != ENOENT)
 189                         log_warning_errno(errno, "Could not kill %d: %m", pid);
 190
 191                 if (send_sighup) {
 192                         /* Optionally, also send a SIGHUP signal, but
 193                         only if the process has a controlling
 194                         tty. This is useful to allow handling of
 195                         shells which ignore SIGTERM but react to
 196                         SIGHUP. We do not send this to processes that
 197                         have no controlling TTY since we don't want to
 198                         trigger reloads of daemon processes. Also we
 199                         make sure to only send this after SIGTERM so
 200                         that SIGTERM is always first in the queue. */
 201
 202
 203                         if (get_ctty_devnr(pid, NULL) >= 0)
 204                                 kill(pid, SIGHUP);
 205                 }
 206         }
 207
 208         return set_size(pids);
 209 }
 210
 211 void broadcast_signal(int sig, bool wait_for_exit, bool send_sighup) {
 212         sigset_t mask, oldmask;
 213         _cleanup_set_free_ Set *pids = NULL;
 214
 215         if (wait_for_exit)
 216                 pids = set_new(NULL);
 217
 218         assert_se(sigemptyset(&mask) == 0);
 219         assert_se(sigaddset(&mask, SIGCHLD) == 0);
 220         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
 221
 222         if (kill(-1, SIGSTOP) < 0 && errno != ESRCH)
 223                 log_warning_errno(errno, "kill(-1, SIGSTOP) failed: %m");
 224
 225         killall(sig, pids, send_sighup);
 226
 227         if (kill(-1, SIGCONT) < 0 && errno != ESRCH)
 228                 log_warning_errno(errno, "kill(-1, SIGCONT) failed: %m");
 229
 230         if (wait_for_exit)
 231                 wait_for_children(pids, &mask);
 232
 233         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 234 }