lib/getfilecon.c

   1 /* wrap getfilecon, lgetfilecon, and fgetfilecon
   2    Copyright (C) 2009-2020 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, or (at your option)
   7    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 /* written by Jim Meyering */
  18
  19 #include <config.h>
  20
  21 #include <selinux/selinux.h>
  22
  23 #include <sys/types.h>
  24 #include <errno.h>
  25 #include <string.h>
  26
  27 /* FIXME: remove this once there is an errno-gnu module
  28    that guarantees the definition of ENODATA.  */
  29 #ifndef ENODATA
  30 # define ENODATA ENOTSUP
  31 #endif
  32
  33 #undef getfilecon
  34 #undef lgetfilecon
  35 #undef fgetfilecon
  36 int getfilecon (char const *file, char **con);
  37 int lgetfilecon (char const *file, char **con);
  38 int fgetfilecon (int fd, char **con);
  39
  40 /* getfilecon, lgetfilecon, and fgetfilecon can all misbehave, be it
  41    via an old version of libselinux where these would return 0 and set the
  42    result context to NULL, or via a modern kernel+lib operating on a file
  43    from a disk whose attributes were set by a kernel from around 2006.
  44    In that latter case, the functions return a length of 10 for the
  45    "unlabeled" context.  Map both failures to a return value of -1, and
  46    set errno to ENOTSUP in the first case, and ENODATA in the latter.  */
  47
  48 static int
  49 map_to_failure (int ret, char **con)
  50 {
  51   if (ret == 0)
  52     {
  53       errno = ENOTSUP;
  54       return -1;
  55     }
  56
  57   if (ret == 10 && strcmp (*con, "unlabeled") == 0)
  58     {
  59       freecon (*con);
  60       *con = NULL;
  61       errno = ENODATA;
  62       return -1;
  63     }
  64
  65   return ret;
  66 }
  67
  68 int
  69 rpl_getfilecon (char const *file, char **con)
  70 {
  71   int ret = getfilecon (file, con);
  72   return map_to_failure (ret, con);
  73 }
  74
  75 int
  76 rpl_lgetfilecon (char const *file, char **con)
  77 {
  78   int ret = lgetfilecon (file, con);
  79   return map_to_failure (ret, con);
  80 }
  81
  82 int
  83 rpl_fgetfilecon (int fd, char**con)
  84 {
  85   int ret = fgetfilecon (fd, con);
  86   return map_to_failure (ret, con);
  87 }