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