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 "alloc-util.h"
  28 #include "fd-util.h"
  29 #include "formats-util.h"
  30 #include "killall.h"
  31 #include "parse-util.h"
  32 #include "process-util.h"
  33 #include "set.h"
  34 #include "string-util.h"
  35 #include "terminal-util.h"
  36 #include "util.h"
  37
  38 #define TIMEOUT_USEC (10 * USEC_PER_SEC)
  39
  40 static bool ignore_proc(pid_t pid) {
  41         _cleanup_fclose_ FILE *f = NULL;
  42         char c;
  43         const char *p;
  44         size_t count;
  45         uid_t uid;
  46         int r;
  47
  48         /* We are PID 1, let's not commit suicide */
  49         if (pid == 1)
  50                 return true;
  51
  52         r = get_process_uid(pid, &uid);
  53         if (r < 0)
  54                 return true; /* not really, but better safe than sorry */
  55
  56         /* Non-root processes otherwise are always subject to be killed */
  57         if (uid != 0)
  58                 return false;
  59
  60         p = procfs_file_alloca(pid, "cmdline");
  61         f = fopen(p, "re");
  62         if (!f)
  63                 return true; /* not really, but has the desired effect */
  64
  65         count = fread(&c, 1, 1, f);
  66
  67         /* Kernel threads have an empty cmdline */
  68         if (count <= 0)
  69                 return true;
  70
  71         /* Processes with argv[0][0] = '@' we ignore from the killing
  72          * spree.
  73          *
  74          * http://www.freedesktop.org/wiki/Software/systemd/RootStorageDaemons */
  75         if (count == 1 && c == '@')
  76                 return true;
  77
  78         return false;
  79 }
  80
  81 static void wait_for_children(Set *pids, sigset_t *mask) {
  82         usec_t until;
  83
  84         assert(mask);
  85
  86         if (set_isempty(pids))
  87                 return;
  88
  89         until = now(CLOCK_MONOTONIC) + TIMEOUT_USEC;
  90         for (;;) {
  91                 struct timespec ts;
  92                 int k;
  93                 usec_t n;
  94                 void *p;
  95                 Iterator i;
  96
  97                 /* First, let the kernel inform us about killed
  98                  * children. Most processes will probably be our
  99                  * children, but some are not (might be our
 100                  * grandchildren instead...). */
 101                 for (;;) {
 102                         pid_t pid;
 103
 104                         pid = waitpid(-1, NULL, WNOHANG);
 105                         if (pid == 0)
 106                                 break;
 107                         if (pid < 0) {
 108                                 if (errno == ECHILD)
 109                                         break;
 110
 111                                 log_error_errno(errno, "waitpid() failed: %m");
 112                                 return;
 113                         }
 114
 115                         (void) set_remove(pids, PID_TO_PTR(pid));
 116                 }
 117
 118                 /* Now explicitly check who might be remaining, who
 119                  * might not be our child. */
 120                 SET_FOREACH(p, pids, i) {
 121
 122                         /* We misuse getpgid as a check whether a
 123                          * process still exists. */
 124                         if (getpgid(PTR_TO_PID(p)) >= 0)
 125                                 continue;
 126
 127                         if (errno != ESRCH)
 128                                 continue;
 129
 130                         set_remove(pids, p);
 131                 }
 132
 133                 if (set_isempty(pids))
 134                         return;
 135
 136                 n = now(CLOCK_MONOTONIC);
 137                 if (n >= until)
 138                         return;
 139
 140                 timespec_store(&ts, until - n);
 141                 k = sigtimedwait(mask, NULL, &ts);
 142                 if (k != SIGCHLD) {
 143
 144                         if (k < 0 && errno != EAGAIN) {
 145                                 log_error_errno(errno, "sigtimedwait() failed: %m");
 146                                 return;
 147                         }
 148
 149                         if (k >= 0)
 150                                 log_warning("sigtimedwait() returned unexpected signal.");
 151                 }
 152         }
 153 }
 154
 155 static int killall(int sig, Set *pids, bool send_sighup) {
 156         _cleanup_closedir_ DIR *dir = NULL;
 157         struct dirent *d;
 158
 159         dir = opendir("/proc");
 160         if (!dir)
 161                 return -errno;
 162
 163         while ((d = readdir(dir))) {
 164                 pid_t pid;
 165                 int r;
 166
 167                 if (d->d_type != DT_DIR &&
 168                     d->d_type != DT_UNKNOWN)
 169                         continue;
 170
 171                 if (parse_pid(d->d_name, &pid) < 0)
 172                         continue;
 173
 174                 if (ignore_proc(pid))
 175                         continue;
 176
 177                 if (sig == SIGKILL) {
 178                         _cleanup_free_ char *s = NULL;
 179
 180                         get_process_comm(pid, &s);
 181                         log_notice("Sending SIGKILL to PID "PID_FMT" (%s).", pid, strna(s));
 182                 }
 183
 184                 if (kill(pid, sig) >= 0) {
 185                         if (pids) {
 186                                 r = set_put(pids, PID_TO_PTR(pid));
 187                                 if (r < 0)
 188                                         log_oom();
 189                         }
 190                 } else if (errno != ENOENT)
 191                         log_warning_errno(errno, "Could not kill %d: %m", pid);
 192
 193                 if (send_sighup) {
 194                         /* Optionally, also send a SIGHUP signal, but
 195                         only if the process has a controlling
 196                         tty. This is useful to allow handling of
 197                         shells which ignore SIGTERM but react to
 198                         SIGHUP. We do not send this to processes that
 199                         have no controlling TTY since we don't want to
 200                         trigger reloads of daemon processes. Also we
 201                         make sure to only send this after SIGTERM so
 202                         that SIGTERM is always first in the queue. */
 203
 204
 205                         if (get_ctty_devnr(pid, NULL) >= 0)
 206                                 kill(pid, SIGHUP);
 207                 }
 208         }
 209
 210         return set_size(pids);
 211 }
 212
 213 void broadcast_signal(int sig, bool wait_for_exit, bool send_sighup) {
 214         sigset_t mask, oldmask;
 215         _cleanup_set_free_ Set *pids = NULL;
 216
 217         if (wait_for_exit)
 218                 pids = set_new(NULL);
 219
 220         assert_se(sigemptyset(&mask) == 0);
 221         assert_se(sigaddset(&mask, SIGCHLD) == 0);
 222         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
 223
 224         if (kill(-1, SIGSTOP) < 0 && errno != ESRCH)
 225                 log_warning_errno(errno, "kill(-1, SIGSTOP) failed: %m");
 226
 227         killall(sig, pids, send_sighup);
 228
 229         if (kill(-1, SIGCONT) < 0 && errno != ESRCH)
 230                 log_warning_errno(errno, "kill(-1, SIGCONT) failed: %m");
 231
 232         if (wait_for_exit)
 233                 wait_for_children(pids, &mask);
 234
 235         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 236 }