src/core/killall.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 ProFUSION embedded systems
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <signal.h>
  22 #include <sys/wait.h>
  23 #include <unistd.h>
  24
  25 #include "alloc-util.h"
  26 #include "def.h"
  27 #include "dirent-util.h"
  28 #include "fd-util.h"
  29 #include "format-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 static bool ignore_proc(pid_t pid, bool warn_rootfs) {
  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 spree.
  70          *
  71          * http://www.freedesktop.org/wiki/Software/systemd/RootStorageDaemons */
  72         if (c != '@')
  73                 return false;
  74
  75         if (warn_rootfs &&
  76             pid_from_same_root_fs(pid) == 0) {
  77
  78                 _cleanup_free_ char *comm = NULL;
  79
  80                 get_process_comm(pid, &comm);
  81
  82                 log_notice("Process " PID_FMT " (%s) has been marked to be excluded from killing. It is "
  83                            "running from the root file system, and thus likely to block re-mounting of the "
  84                            "root file system to read-only. Please consider moving it into an initrd file "
  85                            "system instead.", pid, strna(comm));
  86         }
  87
  88         return true;
  89 }
  90
  91 static void wait_for_children(Set *pids, sigset_t *mask) {
  92         usec_t until;
  93
  94         assert(mask);
  95
  96         if (set_isempty(pids))
  97                 return;
  98
  99         until = now(CLOCK_MONOTONIC) + DEFAULT_TIMEOUT_USEC;
 100         for (;;) {
 101                 struct timespec ts;
 102                 int k;
 103                 usec_t n;
 104                 void *p;
 105                 Iterator i;
 106
 107                 /* First, let the kernel inform us about killed
 108                  * children. Most processes will probably be our
 109                  * children, but some are not (might be our
 110                  * grandchildren instead...). */
 111                 for (;;) {
 112                         pid_t pid;
 113
 114                         pid = waitpid(-1, NULL, WNOHANG);
 115                         if (pid == 0)
 116                                 break;
 117                         if (pid < 0) {
 118                                 if (errno == ECHILD)
 119                                         break;
 120
 121                                 log_error_errno(errno, "waitpid() failed: %m");
 122                                 return;
 123                         }
 124
 125                         (void) set_remove(pids, PID_TO_PTR(pid));
 126                 }
 127
 128                 /* Now explicitly check who might be remaining, who
 129                  * might not be our child. */
 130                 SET_FOREACH(p, pids, i) {
 131
 132                         /* We misuse getpgid as a check whether a
 133                          * process still exists. */
 134                         if (getpgid(PTR_TO_PID(p)) >= 0)
 135                                 continue;
 136
 137                         if (errno != ESRCH)
 138                                 continue;
 139
 140                         set_remove(pids, p);
 141                 }
 142
 143                 if (set_isempty(pids))
 144                         return;
 145
 146                 n = now(CLOCK_MONOTONIC);
 147                 if (n >= until)
 148                         return;
 149
 150                 timespec_store(&ts, until - n);
 151                 k = sigtimedwait(mask, NULL, &ts);
 152                 if (k != SIGCHLD) {
 153
 154                         if (k < 0 && errno != EAGAIN) {
 155                                 log_error_errno(errno, "sigtimedwait() failed: %m");
 156                                 return;
 157                         }
 158
 159                         if (k >= 0)
 160                                 log_warning("sigtimedwait() returned unexpected signal.");
 161                 }
 162         }
 163 }
 164
 165 static int killall(int sig, Set *pids, bool send_sighup) {
 166         _cleanup_closedir_ DIR *dir = NULL;
 167         struct dirent *d;
 168
 169         dir = opendir("/proc");
 170         if (!dir)
 171                 return -errno;
 172
 173         FOREACH_DIRENT_ALL(d, dir, break) {
 174                 pid_t pid;
 175                 int r;
 176
 177                 if (d->d_type != DT_DIR &&
 178                     d->d_type != DT_UNKNOWN)
 179                         continue;
 180
 181                 if (parse_pid(d->d_name, &pid) < 0)
 182                         continue;
 183
 184                 if (ignore_proc(pid, sig == SIGKILL && !in_initrd()))
 185                         continue;
 186
 187                 if (sig == SIGKILL) {
 188                         _cleanup_free_ char *s = NULL;
 189
 190                         get_process_comm(pid, &s);
 191                         log_notice("Sending SIGKILL to PID "PID_FMT" (%s).", pid, strna(s));
 192                 }
 193
 194                 if (kill(pid, sig) >= 0) {
 195                         if (pids) {
 196                                 r = set_put(pids, PID_TO_PTR(pid));
 197                                 if (r < 0)
 198                                         log_oom();
 199                         }
 200                 } else if (errno != ENOENT)
 201                         log_warning_errno(errno, "Could not kill %d: %m", pid);
 202
 203                 if (send_sighup) {
 204                         /* Optionally, also send a SIGHUP signal, but
 205                         only if the process has a controlling
 206                         tty. This is useful to allow handling of
 207                         shells which ignore SIGTERM but react to
 208                         SIGHUP. We do not send this to processes that
 209                         have no controlling TTY since we don't want to
 210                         trigger reloads of daemon processes. Also we
 211                         make sure to only send this after SIGTERM so
 212                         that SIGTERM is always first in the queue. */
 213
 214
 215                         if (get_ctty_devnr(pid, NULL) >= 0)
 216                                 kill(pid, SIGHUP);
 217                 }
 218         }
 219
 220         return set_size(pids);
 221 }
 222
 223 void broadcast_signal(int sig, bool wait_for_exit, bool send_sighup) {
 224         sigset_t mask, oldmask;
 225         _cleanup_set_free_ Set *pids = NULL;
 226
 227         if (wait_for_exit)
 228                 pids = set_new(NULL);
 229
 230         assert_se(sigemptyset(&mask) == 0);
 231         assert_se(sigaddset(&mask, SIGCHLD) == 0);
 232         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
 233
 234         if (kill(-1, SIGSTOP) < 0 && errno != ESRCH)
 235                 log_warning_errno(errno, "kill(-1, SIGSTOP) failed: %m");
 236
 237         killall(sig, pids, send_sighup);
 238
 239         if (kill(-1, SIGCONT) < 0 && errno != ESRCH)
 240                 log_warning_errno(errno, "kill(-1, SIGCONT) failed: %m");
 241
 242         if (wait_for_exit)
 243                 wait_for_children(pids, &mask);
 244
 245         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 246 }