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, bool warn_rootfs) {
  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 (c == '@' && warn_rootfs) {
  76                 _cleanup_free_ char *comm = NULL;
  77
  78                 r = pid_from_same_root_fs(pid);
  79                 if (r < 0)
  80                         return true;
  81
  82                 get_process_comm(pid, &comm);
  83
  84                 if (r)
  85                         log_notice("Process " PID_FMT " (%s) has been been marked to be excluded from killing. It is "
  86                                    "running from the root file system, and thus likely to block re-mounting of the "
  87                                    "root file system to read-only. Please consider moving it into an initrd file "
  88                                    "system instead.", pid, strna(comm));
  89                 return true;
  90         } else if (c == '@')
  91                 return true;
  92
  93         return false;
  94 }
  95
  96 static void wait_for_children(Set *pids, sigset_t *mask) {
  97         usec_t until;
  98
  99         assert(mask);
 100
 101         if (set_isempty(pids))
 102                 return;
 103
 104         until = now(CLOCK_MONOTONIC) + TIMEOUT_USEC;
 105         for (;;) {
 106                 struct timespec ts;
 107                 int k;
 108                 usec_t n;
 109                 void *p;
 110                 Iterator i;
 111
 112                 /* First, let the kernel inform us about killed
 113                  * children. Most processes will probably be our
 114                  * children, but some are not (might be our
 115                  * grandchildren instead...). */
 116                 for (;;) {
 117                         pid_t pid;
 118
 119                         pid = waitpid(-1, NULL, WNOHANG);
 120                         if (pid == 0)
 121                                 break;
 122                         if (pid < 0) {
 123                                 if (errno == ECHILD)
 124                                         break;
 125
 126                                 log_error_errno(errno, "waitpid() failed: %m");
 127                                 return;
 128                         }
 129
 130                         (void) set_remove(pids, PID_TO_PTR(pid));
 131                 }
 132
 133                 /* Now explicitly check who might be remaining, who
 134                  * might not be our child. */
 135                 SET_FOREACH(p, pids, i) {
 136
 137                         /* We misuse getpgid as a check whether a
 138                          * process still exists. */
 139                         if (getpgid(PTR_TO_PID(p)) >= 0)
 140                                 continue;
 141
 142                         if (errno != ESRCH)
 143                                 continue;
 144
 145                         set_remove(pids, p);
 146                 }
 147
 148                 if (set_isempty(pids))
 149                         return;
 150
 151                 n = now(CLOCK_MONOTONIC);
 152                 if (n >= until)
 153                         return;
 154
 155                 timespec_store(&ts, until - n);
 156                 k = sigtimedwait(mask, NULL, &ts);
 157                 if (k != SIGCHLD) {
 158
 159                         if (k < 0 && errno != EAGAIN) {
 160                                 log_error_errno(errno, "sigtimedwait() failed: %m");
 161                                 return;
 162                         }
 163
 164                         if (k >= 0)
 165                                 log_warning("sigtimedwait() returned unexpected signal.");
 166                 }
 167         }
 168 }
 169
 170 static int killall(int sig, Set *pids, bool send_sighup) {
 171         _cleanup_closedir_ DIR *dir = NULL;
 172         struct dirent *d;
 173
 174         dir = opendir("/proc");
 175         if (!dir)
 176                 return -errno;
 177
 178         while ((d = readdir(dir))) {
 179                 pid_t pid;
 180                 int r;
 181
 182                 if (d->d_type != DT_DIR &&
 183                     d->d_type != DT_UNKNOWN)
 184                         continue;
 185
 186                 if (parse_pid(d->d_name, &pid) < 0)
 187                         continue;
 188
 189                 if (ignore_proc(pid, sig == SIGKILL && !in_initrd()))
 190                         continue;
 191
 192                 if (sig == SIGKILL) {
 193                         _cleanup_free_ char *s = NULL;
 194
 195                         get_process_comm(pid, &s);
 196                         log_notice("Sending SIGKILL to PID "PID_FMT" (%s).", pid, strna(s));
 197                 }
 198
 199                 if (kill(pid, sig) >= 0) {
 200                         if (pids) {
 201                                 r = set_put(pids, PID_TO_PTR(pid));
 202                                 if (r < 0)
 203                                         log_oom();
 204                         }
 205                 } else if (errno != ENOENT)
 206                         log_warning_errno(errno, "Could not kill %d: %m", pid);
 207
 208                 if (send_sighup) {
 209                         /* Optionally, also send a SIGHUP signal, but
 210                         only if the process has a controlling
 211                         tty. This is useful to allow handling of
 212                         shells which ignore SIGTERM but react to
 213                         SIGHUP. We do not send this to processes that
 214                         have no controlling TTY since we don't want to
 215                         trigger reloads of daemon processes. Also we
 216                         make sure to only send this after SIGTERM so
 217                         that SIGTERM is always first in the queue. */
 218
 219
 220                         if (get_ctty_devnr(pid, NULL) >= 0)
 221                                 kill(pid, SIGHUP);
 222                 }
 223         }
 224
 225         return set_size(pids);
 226 }
 227
 228 void broadcast_signal(int sig, bool wait_for_exit, bool send_sighup) {
 229         sigset_t mask, oldmask;
 230         _cleanup_set_free_ Set *pids = NULL;
 231
 232         if (wait_for_exit)
 233                 pids = set_new(NULL);
 234
 235         assert_se(sigemptyset(&mask) == 0);
 236         assert_se(sigaddset(&mask, SIGCHLD) == 0);
 237         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
 238
 239         if (kill(-1, SIGSTOP) < 0 && errno != ESRCH)
 240                 log_warning_errno(errno, "kill(-1, SIGSTOP) failed: %m");
 241
 242         killall(sig, pids, send_sighup);
 243
 244         if (kill(-1, SIGCONT) < 0 && errno != ESRCH)
 245                 log_warning_errno(errno, "kill(-1, SIGCONT) failed: %m");
 246
 247         if (wait_for_exit)
 248                 wait_for_children(pids, &mask);
 249
 250         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 251 }