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