src/chcon.c

   1 /* chcon -- change security context of files
   2    Copyright (C) 2005-2022 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18 #include <stdio.h>
  19 #include <sys/types.h>
  20 #include <getopt.h>
  21 #include <selinux/selinux.h>
  22
  23 #include "system.h"
  24 #include "dev-ino.h"
  25 #include "die.h"
  26 #include "error.h"
  27 #include "ignore-value.h"
  28 #include "quote.h"
  29 #include "root-dev-ino.h"
  30 #include "selinux-at.h"
  31 #include "xfts.h"
  32
  33 /* The official name of this program (e.g., no 'g' prefix).  */
  34 #define PROGRAM_NAME "chcon"
  35
  36 #define AUTHORS \
  37   proper_name ("Russell Coker"), \
  38   proper_name ("Jim Meyering")
  39
  40 /* If nonzero, and the systems has support for it, change the context
  41    of symbolic links rather than any files they point to.  */
  42 static bool affect_symlink_referent;
  43
  44 /* If true, change the modes of directories recursively. */
  45 static bool recurse;
  46
  47 /* Level of verbosity. */
  48 static bool verbose;
  49
  50 /* Pointer to the device and inode numbers of '/', when --recursive.
  51    Otherwise NULL.  */
  52 static struct dev_ino *root_dev_ino;
  53
  54 /* The name of the context file is being given. */
  55 static char const *specified_context;
  56
  57 /* Specific components of the context */
  58 static char const *specified_user;
  59 static char const *specified_role;
  60 static char const *specified_range;
  61 static char const *specified_type;
  62
  63 /* For long options that have no equivalent short option, use a
  64    non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
  65 enum
  66 {
  67   DEREFERENCE_OPTION = CHAR_MAX + 1,
  68   NO_PRESERVE_ROOT,
  69   PRESERVE_ROOT,
  70   REFERENCE_FILE_OPTION
  71 };
  72
  73 static struct option const long_options[] =
  74 {
  75   {"recursive", no_argument, NULL, 'R'},
  76   {"dereference", no_argument, NULL, DEREFERENCE_OPTION},
  77   {"no-dereference", no_argument, NULL, 'h'},
  78   {"no-preserve-root", no_argument, NULL, NO_PRESERVE_ROOT},
  79   {"preserve-root", no_argument, NULL, PRESERVE_ROOT},
  80   {"reference", required_argument, NULL, REFERENCE_FILE_OPTION},
  81   {"user", required_argument, NULL, 'u'},
  82   {"role", required_argument, NULL, 'r'},
  83   {"type", required_argument, NULL, 't'},
  84   {"range", required_argument, NULL, 'l'},
  85   {"verbose", no_argument, NULL, 'v'},
  86   {GETOPT_HELP_OPTION_DECL},
  87   {GETOPT_VERSION_OPTION_DECL},
  88   {NULL, 0, NULL, 0}
  89 };
  90
  91 /* Given a security context, CONTEXT, derive a context_t (*RET),
  92    setting any portions selected via the global variables, specified_user,
  93    specified_role, etc.  */
  94 static int
  95 compute_context_from_mask (char const *context, context_t *ret)
  96 {
  97   bool ok = true;
  98   context_t new_context = context_new (context);
  99   if (!new_context)
 100     {
 101       error (0, errno, _("failed to create security context: %s"),
 102              quote (context));
 103       return 1;
 104     }
 105
 106 #define SET_COMPONENT(C, comp)                                          \
 107    do                                                                   \
 108      {                                                                  \
 109        if (specified_ ## comp                                           \
 110            && context_ ## comp ## _set ((C), specified_ ## comp))       \
 111          {                                                              \
 112             error (0, errno,                                            \
 113                    _("failed to set %s security context component to %s"), \
 114                    #comp, quote (specified_ ## comp));                  \
 115            ok = false;                                                  \
 116          }                                                              \
 117      }                                                                  \
 118    while (0)
 119
 120   SET_COMPONENT (new_context, user);
 121   SET_COMPONENT (new_context, range);
 122   SET_COMPONENT (new_context, role);
 123   SET_COMPONENT (new_context, type);
 124
 125   if (!ok)
 126     {
 127       int saved_errno = errno;
 128       context_free (new_context);
 129       errno = saved_errno;
 130       return 1;
 131     }
 132
 133   *ret = new_context;
 134   return 0;
 135 }
 136
 137 /* Change the context of FILE, using specified components.
 138    If it is a directory and -R is given, recurse.
 139    Return 0 if successful, 1 if errors occurred. */
 140
 141 static int
 142 change_file_context (int fd, char const *file)
 143 {
 144   char *file_context = NULL;
 145   context_t context IF_LINT (= 0);
 146   char const * context_string;
 147   int errors = 0;
 148
 149   if (specified_context == NULL)
 150     {
 151       int status = (affect_symlink_referent
 152                     ? getfileconat (fd, file, &file_context)
 153                     : lgetfileconat (fd, file, &file_context));
 154
 155       if (status < 0 && errno != ENODATA)
 156         {
 157           error (0, errno, _("failed to get security context of %s"),
 158                  quoteaf (file));
 159           return 1;
 160         }
 161
 162       /* If the file doesn't have a context, and we're not setting all of
 163          the context components, there isn't really an obvious default.
 164          Thus, we just give up. */
 165       if (file_context == NULL)
 166         {
 167           error (0, 0, _("can't apply partial context to unlabeled file %s"),
 168                  quoteaf (file));
 169           return 1;
 170         }
 171
 172       if (compute_context_from_mask (file_context, &context))
 173         return 1;
 174
 175       context_string = context_str (context);
 176     }
 177   else
 178     {
 179       context_string = specified_context;
 180     }
 181
 182   if (file_context == NULL || ! STREQ (context_string, file_context))
 183     {
 184       int fail = (affect_symlink_referent
 185                   ?  setfileconat (fd, file, context_string)
 186                   : lsetfileconat (fd, file, context_string));
 187
 188       if (fail)
 189         {
 190           errors = 1;
 191           error (0, errno, _("failed to change context of %s to %s"),
 192                  quoteaf_n (0, file), quote_n (1, context_string));
 193         }
 194     }
 195
 196   if (specified_context == NULL)
 197     {
 198       context_free (context);
 199       freecon (file_context);
 200     }
 201
 202   return errors;
 203 }
 204
 205 /* Change the context of FILE.
 206    Return true if successful.  This function is called
 207    once for every file system object that fts encounters.  */
 208
 209 static bool
 210 process_file (FTS *fts, FTSENT *ent)
 211 {
 212   char const *file_full_name = ent->fts_path;
 213   char const *file = ent->fts_accpath;
 214   const struct stat *file_stats = ent->fts_statp;
 215   bool ok = true;
 216
 217   switch (ent->fts_info)
 218     {
 219     case FTS_D:
 220       if (recurse)
 221         {
 222           if (ROOT_DEV_INO_CHECK (root_dev_ino, ent->fts_statp))
 223             {
 224               /* This happens e.g., with "chcon -R --preserve-root ... /"
 225                  and with "chcon -RH --preserve-root ... symlink-to-root".  */
 226               ROOT_DEV_INO_WARN (file_full_name);
 227               /* Tell fts not to traverse into this hierarchy.  */
 228               fts_set (fts, ent, FTS_SKIP);
 229               /* Ensure that we do not process "/" on the second visit.  */
 230               ignore_value (fts_read (fts));
 231               return false;
 232             }
 233           return true;
 234         }
 235       break;
 236
 237     case FTS_DP:
 238       if (! recurse)
 239         return true;
 240       break;
 241
 242     case FTS_NS:
 243       /* For a top-level file or directory, this FTS_NS (stat failed)
 244          indicator is determined at the time of the initial fts_open call.
 245          With programs like chmod, chown, and chgrp, that modify
 246          permissions, it is possible that the file in question is
 247          accessible when control reaches this point.  So, if this is
 248          the first time we've seen the FTS_NS for this file, tell
 249          fts_read to stat it "again".  */
 250       if (ent->fts_level == 0 && ent->fts_number == 0)
 251         {
 252           ent->fts_number = 1;
 253           fts_set (fts, ent, FTS_AGAIN);
 254           return true;
 255         }
 256       error (0, ent->fts_errno, _("cannot access %s"),
 257              quoteaf (file_full_name));
 258       ok = false;
 259       break;
 260
 261     case FTS_ERR:
 262       error (0, ent->fts_errno, "%s", quotef (file_full_name));
 263       ok = false;
 264       break;
 265
 266     case FTS_DNR:
 267       error (0, ent->fts_errno, _("cannot read directory %s"),
 268              quoteaf (file_full_name));
 269       ok = false;
 270       break;
 271
 272     case FTS_DC:                /* directory that causes cycles */
 273       if (cycle_warning_required (fts, ent))
 274         {
 275           emit_cycle_warning (file_full_name);
 276           return false;
 277         }
 278       break;
 279
 280     default:
 281       break;
 282     }
 283
 284   if (ent->fts_info == FTS_DP
 285       && ok && ROOT_DEV_INO_CHECK (root_dev_ino, file_stats))
 286     {
 287       ROOT_DEV_INO_WARN (file_full_name);
 288       ok = false;
 289     }
 290
 291   if (ok)
 292     {
 293       if (verbose)
 294         printf (_("changing security context of %s\n"),
 295                 quoteaf (file_full_name));
 296
 297       if (change_file_context (fts->fts_cwd_fd, file) != 0)
 298         ok = false;
 299     }
 300
 301   if ( ! recurse)
 302     fts_set (fts, ent, FTS_SKIP);
 303
 304   return ok;
 305 }
 306
 307 /* Recursively operate on the specified FILES (the last entry
 308    of which is NULL).  BIT_FLAGS controls how fts works.
 309    Return true if successful.  */
 310
 311 static bool
 312 process_files (char **files, int bit_flags)
 313 {
 314   bool ok = true;
 315
 316   FTS *fts = xfts_open (files, bit_flags, NULL);
 317
 318   while (true)
 319     {
 320       FTSENT *ent;
 321
 322       ent = fts_read (fts);
 323       if (ent == NULL)
 324         {
 325           if (errno != 0)
 326             {
 327               /* FIXME: try to give a better message  */
 328               error (0, errno, _("fts_read failed"));
 329               ok = false;
 330             }
 331           break;
 332         }
 333
 334       ok &= process_file (fts, ent);
 335     }
 336
 337   if (fts_close (fts) != 0)
 338     {
 339       error (0, errno, _("fts_close failed"));
 340       ok = false;
 341     }
 342
 343   return ok;
 344 }
 345
 346 void
 347 usage (int status)
 348 {
 349   if (status != EXIT_SUCCESS)
 350     emit_try_help ();
 351   else
 352     {
 353       printf (_("\
 354 Usage: %s [OPTION]... CONTEXT FILE...\n\
 355   or:  %s [OPTION]... [-u USER] [-r ROLE] [-l RANGE] [-t TYPE] FILE...\n\
 356   or:  %s [OPTION]... --reference=RFILE FILE...\n\
 357 "),
 358         program_name, program_name, program_name);
 359       fputs (_("\
 360 Change the SELinux security context of each FILE to CONTEXT.\n\
 361 With --reference, change the security context of each FILE to that of RFILE.\n\
 362 "), stdout);
 363
 364       emit_mandatory_arg_note ();
 365
 366       fputs (_("\
 367       --dereference      affect the referent of each symbolic link (this is\n\
 368                          the default), rather than the symbolic link itself\n\
 369   -h, --no-dereference   affect symbolic links instead of any referenced file\n\
 370 "), stdout);
 371       fputs (_("\
 372   -u, --user=USER        set user USER in the target security context\n\
 373   -r, --role=ROLE        set role ROLE in the target security context\n\
 374   -t, --type=TYPE        set type TYPE in the target security context\n\
 375   -l, --range=RANGE      set range RANGE in the target security context\n\
 376 "), stdout);
 377       fputs (_("\
 378       --no-preserve-root  do not treat '/' specially (the default)\n\
 379       --preserve-root    fail to operate recursively on '/'\n\
 380 "), stdout);
 381       fputs (_("\
 382       --reference=RFILE  use RFILE's security context rather than specifying\n\
 383                          a CONTEXT value\n\
 384 "), stdout);
 385       fputs (_("\
 386   -R, --recursive        operate on files and directories recursively\n\
 387 "), stdout);
 388       fputs (_("\
 389   -v, --verbose          output a diagnostic for every file processed\n\
 390 "), stdout);
 391       fputs (_("\
 392 \n\
 393 The following options modify how a hierarchy is traversed when the -R\n\
 394 option is also specified.  If more than one is specified, only the final\n\
 395 one takes effect.\n\
 396 \n\
 397   -H                     if a command line argument is a symbolic link\n\
 398                          to a directory, traverse it\n\
 399   -L                     traverse every symbolic link to a directory\n\
 400                          encountered\n\
 401   -P                     do not traverse any symbolic links (default)\n\
 402 \n\
 403 "), stdout);
 404       fputs (HELP_OPTION_DESCRIPTION, stdout);
 405       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 406       emit_ancillary_info (PROGRAM_NAME);
 407     }
 408   exit (status);
 409 }
 410
 411 int
 412 main (int argc, char **argv)
 413 {
 414   /* Bit flags that control how fts works.  */
 415   int bit_flags = FTS_PHYSICAL;
 416
 417   /* 1 if --dereference, 0 if --no-dereference, -1 if neither has been
 418      specified.  */
 419   int dereference = -1;
 420
 421   bool ok;
 422   bool preserve_root = false;
 423   bool component_specified = false;
 424   char *reference_file = NULL;
 425   int optc;
 426
 427   initialize_main (&argc, &argv);
 428   set_program_name (argv[0]);
 429   setlocale (LC_ALL, "");
 430   bindtextdomain (PACKAGE, LOCALEDIR);
 431   textdomain (PACKAGE);
 432
 433   atexit (close_stdout);
 434
 435   while ((optc = getopt_long (argc, argv, "HLPRhvu:r:t:l:", long_options, NULL))
 436          != -1)
 437     {
 438       switch (optc)
 439         {
 440         case 'H': /* Traverse command-line symlinks-to-directories.  */
 441           bit_flags = FTS_COMFOLLOW | FTS_PHYSICAL;
 442           break;
 443
 444         case 'L': /* Traverse all symlinks-to-directories.  */
 445           bit_flags = FTS_LOGICAL;
 446           break;
 447
 448         case 'P': /* Traverse no symlinks-to-directories.  */
 449           bit_flags = FTS_PHYSICAL;
 450           break;
 451
 452         case 'h': /* --no-dereference: affect symlinks */
 453           dereference = 0;
 454           break;
 455
 456         case DEREFERENCE_OPTION: /* --dereference: affect the referent
 457                                     of each symlink */
 458           dereference = 1;
 459           break;
 460
 461         case NO_PRESERVE_ROOT:
 462           preserve_root = false;
 463           break;
 464
 465         case PRESERVE_ROOT:
 466           preserve_root = true;
 467           break;
 468
 469         case REFERENCE_FILE_OPTION:
 470           reference_file = optarg;
 471           break;
 472
 473         case 'R':
 474           recurse = true;
 475           break;
 476
 477         case 'f':
 478           /* ignore */
 479           break;
 480
 481         case 'v':
 482           verbose = true;
 483           break;
 484
 485         case 'u':
 486           specified_user = optarg;
 487           component_specified = true;
 488           break;
 489
 490         case 'r':
 491           specified_role = optarg;
 492           component_specified = true;
 493           break;
 494
 495         case 't':
 496           specified_type = optarg;
 497           component_specified = true;
 498           break;
 499
 500         case 'l':
 501           specified_range = optarg;
 502           component_specified = true;
 503           break;
 504
 505         case_GETOPT_HELP_CHAR;
 506         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 507         default:
 508           usage (EXIT_FAILURE);
 509         }
 510     }
 511
 512   if (recurse)
 513     {
 514       if (bit_flags == FTS_PHYSICAL)
 515         {
 516           if (dereference == 1)
 517             die (EXIT_FAILURE, 0,
 518                  _("-R --dereference requires either -H or -L"));
 519           affect_symlink_referent = false;
 520         }
 521       else
 522         {
 523           if (dereference == 0)
 524             die (EXIT_FAILURE, 0, _("-R -h requires -P"));
 525           affect_symlink_referent = true;
 526         }
 527     }
 528   else
 529     {
 530       bit_flags = FTS_PHYSICAL;
 531       affect_symlink_referent = (dereference != 0);
 532     }
 533
 534   if (argc - optind < (reference_file || component_specified ? 1 : 2))
 535     {
 536       if (argc <= optind)
 537         error (0, 0, _("missing operand"));
 538       else
 539         error (0, 0, _("missing operand after %s"), quote (argv[argc - 1]));
 540       usage (EXIT_FAILURE);
 541     }
 542
 543   if (reference_file)
 544     {
 545       char *ref_context = NULL;
 546
 547       if (getfilecon (reference_file, &ref_context) < 0)
 548         die (EXIT_FAILURE, errno, _("failed to get security context of %s"),
 549              quoteaf (reference_file));
 550
 551       specified_context = ref_context;
 552     }
 553   else if (component_specified)
 554     {
 555       /* FIXME: it's already null, so this is a no-op. */
 556       specified_context = NULL;
 557     }
 558   else
 559     {
 560       specified_context = argv[optind++];
 561       if (0 < is_selinux_enabled ()
 562           && security_check_context (specified_context) < 0)
 563         die (EXIT_FAILURE, errno, _("invalid context: %s"),
 564              quote (specified_context));
 565     }
 566
 567   if (reference_file && component_specified)
 568     {
 569       error (0, 0, _("conflicting security context specifiers given"));
 570       usage (EXIT_FAILURE);
 571     }
 572
 573   if (recurse && preserve_root)
 574     {
 575       static struct dev_ino dev_ino_buf;
 576       root_dev_ino = get_root_dev_ino (&dev_ino_buf);
 577       if (root_dev_ino == NULL)
 578         die (EXIT_FAILURE, errno, _("failed to get attributes of %s"),
 579              quoteaf ("/"));
 580     }
 581   else
 582     {
 583       root_dev_ino = NULL;
 584     }
 585
 586   ok = process_files (argv + optind, bit_flags | FTS_NOSTAT);
 587
 588   return ok ? EXIT_SUCCESS : EXIT_FAILURE;
 589 }