src/shared/exec-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <dirent.h>
   4 #include <errno.h>
   5 #include <sys/prctl.h>
   6 #include <sys/types.h>
   7 #include <unistd.h>
   8 #include <stdio.h>
   9
  10 #include "alloc-util.h"
  11 #include "conf-files.h"
  12 #include "env-file.h"
  13 #include "env-util.h"
  14 #include "exec-util.h"
  15 #include "fd-util.h"
  16 #include "fileio.h"
  17 #include "hashmap.h"
  18 #include "macro.h"
  19 #include "process-util.h"
  20 #include "rlimit-util.h"
  21 #include "serialize.h"
  22 #include "set.h"
  23 #include "signal-util.h"
  24 #include "stat-util.h"
  25 #include "string-util.h"
  26 #include "strv.h"
  27 #include "terminal-util.h"
  28 #include "tmpfile-util.h"
  29 #include "util.h"
  30
  31 /* Put this test here for a lack of better place */
  32 assert_cc(EAGAIN == EWOULDBLOCK);
  33
  34 static int do_spawn(const char *path, char *argv[], int stdout_fd, pid_t *pid) {
  35
  36         pid_t _pid;
  37         int r;
  38
  39         if (null_or_empty_path(path)) {
  40                 log_debug("%s is empty (a mask).", path);
  41                 return 0;
  42         }
  43
  44         r = safe_fork("(direxec)", FORK_DEATHSIG|FORK_LOG, &_pid);
  45         if (r < 0)
  46                 return r;
  47         if (r == 0) {
  48                 char *_argv[2];
  49
  50                 if (stdout_fd >= 0) {
  51                         r = rearrange_stdio(STDIN_FILENO, stdout_fd, STDERR_FILENO);
  52                         if (r < 0)
  53                                 _exit(EXIT_FAILURE);
  54                 }
  55
  56                 (void) rlimit_nofile_safe();
  57
  58                 if (!argv) {
  59                         _argv[0] = (char*) path;
  60                         _argv[1] = NULL;
  61                         argv = _argv;
  62                 } else
  63                         argv[0] = (char*) path;
  64
  65                 execv(path, argv);
  66                 log_error_errno(errno, "Failed to execute %s: %m", path);
  67                 _exit(EXIT_FAILURE);
  68         }
  69
  70         *pid = _pid;
  71         return 1;
  72 }
  73
  74 static int do_execute(
  75                 char **directories,
  76                 usec_t timeout,
  77                 gather_stdout_callback_t const callbacks[_STDOUT_CONSUME_MAX],
  78                 void* const callback_args[_STDOUT_CONSUME_MAX],
  79                 int output_fd,
  80                 char *argv[],
  81                 char *envp[]) {
  82
  83         _cleanup_hashmap_free_free_ Hashmap *pids = NULL;
  84         _cleanup_strv_free_ char **paths = NULL;
  85         char **path, **e;
  86         int r;
  87
  88         /* We fork this all off from a child process so that we can somewhat cleanly make
  89          * use of SIGALRM to set a time limit.
  90          *
  91          * If callbacks is nonnull, execution is serial. Otherwise, we default to parallel.
  92          */
  93
  94         r = conf_files_list_strv(&paths, NULL, NULL, CONF_FILES_EXECUTABLE|CONF_FILES_REGULAR|CONF_FILES_FILTER_MASKED, (const char* const*) directories);
  95         if (r < 0)
  96                 return log_error_errno(r, "Failed to enumerate executables: %m");
  97
  98         if (!callbacks) {
  99                 pids = hashmap_new(NULL);
 100                 if (!pids)
 101                         return log_oom();
 102         }
 103
 104         /* Abort execution of this process after the timout. We simply rely on SIGALRM as
 105          * default action terminating the process, and turn on alarm(). */
 106
 107         if (timeout != USEC_INFINITY)
 108                 alarm(DIV_ROUND_UP(timeout, USEC_PER_SEC));
 109
 110         STRV_FOREACH(e, envp)
 111                 if (putenv(*e) != 0)
 112                         return log_error_errno(errno, "Failed to set environment variable: %m");
 113
 114         STRV_FOREACH(path, paths) {
 115                 _cleanup_free_ char *t = NULL;
 116                 _cleanup_close_ int fd = -1;
 117                 pid_t pid;
 118
 119                 t = strdup(*path);
 120                 if (!t)
 121                         return log_oom();
 122
 123                 if (callbacks) {
 124                         fd = open_serialization_fd(basename(*path));
 125                         if (fd < 0)
 126                                 return log_error_errno(fd, "Failed to open serialization file: %m");
 127                 }
 128
 129                 r = do_spawn(t, argv, fd, &pid);
 130                 if (r <= 0)
 131                         continue;
 132
 133                 if (pids) {
 134                         r = hashmap_put(pids, PID_TO_PTR(pid), t);
 135                         if (r < 0)
 136                                 return log_oom();
 137                         t = NULL;
 138                 } else {
 139                         r = wait_for_terminate_and_check(t, pid, WAIT_LOG);
 140                         if (r < 0)
 141                                 continue;
 142
 143                         if (lseek(fd, 0, SEEK_SET) < 0)
 144                                 return log_error_errno(errno, "Failed to seek on serialization fd: %m");
 145
 146                         r = callbacks[STDOUT_GENERATE](fd, callback_args[STDOUT_GENERATE]);
 147                         fd = -1;
 148                         if (r < 0)
 149                                 return log_error_errno(r, "Failed to process output from %s: %m", *path);
 150                 }
 151         }
 152
 153         if (callbacks) {
 154                 r = callbacks[STDOUT_COLLECT](output_fd, callback_args[STDOUT_COLLECT]);
 155                 if (r < 0)
 156                         return log_error_errno(r, "Callback two failed: %m");
 157         }
 158
 159         while (!hashmap_isempty(pids)) {
 160                 _cleanup_free_ char *t = NULL;
 161                 pid_t pid;
 162
 163                 pid = PTR_TO_PID(hashmap_first_key(pids));
 164                 assert(pid > 0);
 165
 166                 t = hashmap_remove(pids, PID_TO_PTR(pid));
 167                 assert(t);
 168
 169                 (void) wait_for_terminate_and_check(t, pid, WAIT_LOG);
 170         }
 171
 172         return 0;
 173 }
 174
 175 int execute_directories(
 176                 const char* const* directories,
 177                 usec_t timeout,
 178                 gather_stdout_callback_t const callbacks[_STDOUT_CONSUME_MAX],
 179                 void* const callback_args[_STDOUT_CONSUME_MAX],
 180                 char *argv[],
 181                 char *envp[]) {
 182
 183         char **dirs = (char**) directories;
 184         _cleanup_close_ int fd = -1;
 185         char *name;
 186         int r;
 187
 188         assert(!strv_isempty(dirs));
 189
 190         name = basename(dirs[0]);
 191         assert(!isempty(name));
 192
 193         if (callbacks) {
 194                 assert(callback_args);
 195                 assert(callbacks[STDOUT_GENERATE]);
 196                 assert(callbacks[STDOUT_COLLECT]);
 197                 assert(callbacks[STDOUT_CONSUME]);
 198
 199                 fd = open_serialization_fd(name);
 200                 if (fd < 0)
 201                         return log_error_errno(fd, "Failed to open serialization file: %m");
 202         }
 203
 204         /* Executes all binaries in the directories serially or in parallel and waits for
 205          * them to finish. Optionally a timeout is applied. If a file with the same name
 206          * exists in more than one directory, the earliest one wins. */
 207
 208         r = safe_fork("(sd-executor)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_LOG|FORK_WAIT, NULL);
 209         if (r < 0)
 210                 return r;
 211         if (r == 0) {
 212                 r = do_execute(dirs, timeout, callbacks, callback_args, fd, argv, envp);
 213                 _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
 214         }
 215
 216         if (!callbacks)
 217                 return 0;
 218
 219         if (lseek(fd, 0, SEEK_SET) < 0)
 220                 return log_error_errno(errno, "Failed to rewind serialization fd: %m");
 221
 222         r = callbacks[STDOUT_CONSUME](fd, callback_args[STDOUT_CONSUME]);
 223         fd = -1;
 224         if (r < 0)
 225                 return log_error_errno(r, "Failed to parse returned data: %m");
 226         return 0;
 227 }
 228
 229 static int gather_environment_generate(int fd, void *arg) {
 230         char ***env = arg, **x, **y;
 231         _cleanup_fclose_ FILE *f = NULL;
 232         _cleanup_strv_free_ char **new = NULL;
 233         int r;
 234
 235         /* Read a series of VAR=value assignments from fd, use them to update the list of
 236          * variables in env. Also update the exported environment.
 237          *
 238          * fd is always consumed, even on error.
 239          */
 240
 241         assert(env);
 242
 243         f = fdopen(fd, "r");
 244         if (!f) {
 245                 safe_close(fd);
 246                 return -errno;
 247         }
 248
 249         r = load_env_file_pairs(f, NULL, &new);
 250         if (r < 0)
 251                 return r;
 252
 253         STRV_FOREACH_PAIR(x, y, new) {
 254                 char *p;
 255
 256                 if (!env_name_is_valid(*x)) {
 257                         log_warning("Invalid variable assignment \"%s=...\", ignoring.", *x);
 258                         continue;
 259                 }
 260
 261                 p = strjoin(*x, "=", *y);
 262                 if (!p)
 263                         return -ENOMEM;
 264
 265                 r = strv_env_replace(env, p);
 266                 if (r < 0)
 267                         return r;
 268
 269                 if (setenv(*x, *y, true) < 0)
 270                         return -errno;
 271         }
 272
 273         return r;
 274 }
 275
 276 static int gather_environment_collect(int fd, void *arg) {
 277         _cleanup_fclose_ FILE *f = NULL;
 278         char ***env = arg;
 279         int r;
 280
 281         /* Write out a series of env=cescape(VAR=value) assignments to fd. */
 282
 283         assert(env);
 284
 285         f = fdopen(fd, "w");
 286         if (!f) {
 287                 safe_close(fd);
 288                 return -errno;
 289         }
 290
 291         r = serialize_strv(f, "env", *env);
 292         if (r < 0)
 293                 return r;
 294
 295         r = fflush_and_check(f);
 296         if (r < 0)
 297                 return r;
 298
 299         return 0;
 300 }
 301
 302 static int gather_environment_consume(int fd, void *arg) {
 303         _cleanup_fclose_ FILE *f = NULL;
 304         char ***env = arg;
 305         int r = 0;
 306
 307         /* Read a series of env=cescape(VAR=value) assignments from fd into env. */
 308
 309         assert(env);
 310
 311         f = fdopen(fd, "re");
 312         if (!f) {
 313                 safe_close(fd);
 314                 return -errno;
 315         }
 316
 317         for (;;) {
 318                 _cleanup_free_ char *line = NULL;
 319                 const char *v;
 320                 int k;
 321
 322                 k = read_line(f, LONG_LINE_MAX, &line);
 323                 if (k < 0)
 324                         return k;
 325                 if (k == 0)
 326                         break;
 327
 328                 v = startswith(line, "env=");
 329                 if (!v) {
 330                         log_debug("Serialization line \"%s\" unexpectedly didn't start with \"env=\".", line);
 331                         if (r == 0)
 332                                 r = -EINVAL;
 333
 334                         continue;
 335                 }
 336
 337                 k = deserialize_environment(v, env);
 338                 if (k < 0) {
 339                         log_debug_errno(k, "Invalid serialization line \"%s\": %m", line);
 340
 341                         if (r == 0)
 342                                 r = k;
 343                 }
 344         }
 345
 346         return r;
 347 }
 348
 349 const gather_stdout_callback_t gather_environment[] = {
 350         gather_environment_generate,
 351         gather_environment_collect,
 352         gather_environment_consume,
 353 };