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