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) {
 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 %lu (%s).", (unsigned long) pid, strna(s));
 174                 }
 175
 176                 if (kill(pid, sig) >= 0) {
 177                         if (pids)
 178                                 set_put(pids, ULONG_TO_PTR((unsigned long) pid));
 179                 } else if (errno != ENOENT)
 180                         log_warning("Could not kill %d: %m", pid);
 181         }
 182
 183         return set_size(pids);
 184 }
 185
 186 void broadcast_signal(int sig, bool wait_for_exit) {
 187         sigset_t mask, oldmask;
 188         Set *pids = NULL;
 189
 190         if (wait_for_exit)
 191                 pids = set_new(trivial_hash_func, trivial_compare_func);
 192
 193         assert_se(sigemptyset(&mask) == 0);
 194         assert_se(sigaddset(&mask, SIGCHLD) == 0);
 195         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
 196
 197         if (kill(-1, SIGSTOP) < 0 && errno != ESRCH)
 198                 log_warning("kill(-1, SIGSTOP) failed: %m");
 199
 200         killall(sig, pids);
 201
 202         if (kill(-1, SIGCONT) < 0 && errno != ESRCH)
 203                 log_warning("kill(-1, SIGCONT) failed: %m");
 204
 205         if (wait_for_exit)
 206                 wait_for_children(pids, &mask);
 207
 208         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 209
 210         set_free(pids);
 211 }