elf/tst-env-setuid.c

   1 /* Copyright (C) 2012-2024 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library 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 GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 /* Verify that correctly filter out unsafe environment variables defined
  19    in unsecvars.h.  */
  20
  21 #include <array_length.h>
  22 #include <gnu/lib-names.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27
  28 #include <support/check.h>
  29 #include <support/support.h>
  30 #include <support/test-driver.h>
  31 #include <support/capture_subprocess.h>
  32
  33 static char SETGID_CHILD[] = "setgid-child";
  34
  35 #define FILTERED_VALUE   "some-filtered-value"
  36 #define UNFILTERED_VALUE "some-unfiltered-value"
  37 /* It assumes no other programs is being profile with a library with same
  38    SONAME using the default folder.  */
  39 #ifndef PROFILE_LIB
  40 # define PROFILE_LIB      "tst-sonamemove-runmod2.so"
  41 #endif
  42
  43 struct envvar_t
  44 {
  45   const char *env;
  46   const char *value;
  47 };
  48
  49 /* That is not an extensible list of all filtered out environment
  50    variables.  */
  51 static const struct envvar_t filtered_envvars[] =
  52 {
  53   { "GLIBC_TUNABLES",          FILTERED_VALUE },
  54   { "LD_AUDIT",                FILTERED_VALUE },
  55   { "LD_HWCAP_MASK",           FILTERED_VALUE },
  56   { "LD_LIBRARY_PATH",         FILTERED_VALUE },
  57   { "LD_PRELOAD",              FILTERED_VALUE },
  58   { "LD_PROFILE",              PROFILE_LIB },
  59   { "MALLOC_ARENA_MAX",        FILTERED_VALUE },
  60   { "MALLOC_PERTURB_",         FILTERED_VALUE },
  61   { "MALLOC_TRACE",            FILTERED_VALUE },
  62   { "MALLOC_TRIM_THRESHOLD_",  FILTERED_VALUE },
  63   { "RES_OPTIONS",             FILTERED_VALUE },
  64   { "LD_DEBUG",                "all" },
  65   { "LD_DEBUG_OUTPUT",         "/tmp/some-file" },
  66   { "LD_WARN",                 FILTERED_VALUE },
  67   { "LD_VERBOSE",              FILTERED_VALUE },
  68   { "LD_BIND_NOW",             "0" },
  69   { "LD_BIND_NOT",             "1" },
  70 };
  71
  72 static const struct envvar_t unfiltered_envvars[] =
  73 {
  74   /* Non longer supported option.  */
  75   { "LD_ASSUME_KERNEL",        UNFILTERED_VALUE },
  76 };
  77
  78 static int
  79 test_child (void)
  80 {
  81   int ret = 0;
  82
  83   for (const struct envvar_t *e = filtered_envvars;
  84        e != array_end (filtered_envvars);
  85        e++)
  86     {
  87       const char *env = getenv (e->env);
  88       if (env != NULL)
  89         {
  90           printf ("FAIL: filtered environment variable is not NULL: %s=%s\n",
  91                   e->env, env);
  92           ret = 1;
  93         }
  94     }
  95
  96   for (const struct envvar_t *e = unfiltered_envvars;
  97        e != array_end (unfiltered_envvars);
  98        e++)
  99     {
 100       const char *env = getenv (e->env);
 101       if (!(env != NULL && strcmp (env, e->value) == 0))
 102         {
 103           if (env == NULL)
 104             printf ("FAIL: unfiltered environment variable %s is NULL\n",
 105                     e->env);
 106           else
 107             printf ("FAIL: unfiltered environment variable %s=%s != %s\n",
 108                     e->env, env, e->value);
 109
 110           ret = 1;
 111         }
 112     }
 113
 114   /* Also check if no profile file was created.
 115      The parent sets LD_DEBUG_OUTPUT="/tmp/some-file"
 116      which should be filtered.  Then it falls back to "/var/tmp".
 117      Note: LD_PROFILE is not supported for static binaries.  */
 118   {
 119     char *profilepath = xasprintf ("/var/tmp/%s.profile", PROFILE_LIB);
 120     if (!access (profilepath, R_OK))
 121       {
 122         printf ("FAIL: LD_PROFILE file at %s was created!\n", profilepath);
 123         ret = 1;
 124       }
 125     free (profilepath);
 126   }
 127
 128   return ret;
 129 }
 130
 131 static int
 132 do_test (int argc, char **argv)
 133 {
 134   /* For dynamic loader, the test requires --enable-hardcoded-path-in-tests so
 135      the kernel sets the AT_SECURE on process initialization.  */
 136   if (argc >= 2 && strstr (argv[1], LD_SO) != 0)
 137     FAIL_UNSUPPORTED ("dynamic test requires --enable-hardcoded-path-in-tests");
 138
 139   /* Setgid child process.  */
 140   if (argc == 2 && strcmp (argv[1], SETGID_CHILD) == 0)
 141     {
 142       if (getgid () == getegid ())
 143         /* This can happen if the file system is mounted nosuid.  */
 144         FAIL_UNSUPPORTED ("SGID failed: GID and EGID match (%jd)\n",
 145                           (intmax_t) getgid ());
 146
 147       int ret = test_child ();
 148
 149       if (ret != 0)
 150         exit (1);
 151
 152       /* Special return code to make sure that the child executed all the way
 153          through.  */
 154       exit (42);
 155     }
 156   else
 157     {
 158       for (const struct envvar_t *e = filtered_envvars;
 159            e != array_end (filtered_envvars);
 160            e++)
 161         setenv (e->env, e->value, 1);
 162
 163       for (const struct envvar_t *e = unfiltered_envvars;
 164            e != array_end (unfiltered_envvars);
 165            e++)
 166         setenv (e->env, e->value, 1);
 167
 168       /* Ensure that the profile output does not exist from a previous run
 169          (e.g. if test_dir, which defaults to /tmp, is mounted nosuid.)
 170          Note: support_capture_subprogram_self_sgid creates the SGID binary
 171          in test_dir.  */
 172       {
 173         char *profilepath = xasprintf ("/var/tmp/%s.profile", PROFILE_LIB);
 174         unlink (profilepath);
 175         free (profilepath);
 176       }
 177
 178       int status = support_capture_subprogram_self_sgid (SETGID_CHILD);
 179
 180       if (WEXITSTATUS (status) == EXIT_UNSUPPORTED)
 181         exit (EXIT_UNSUPPORTED);
 182
 183       if (WEXITSTATUS (status) != 42)
 184         {
 185           printf ("    child failed with status %d\n",
 186                   WEXITSTATUS (status));
 187           support_record_failure ();
 188         }
 189
 190       return 0;
 191     }
 192 }
 193
 194 #define TEST_FUNCTION_ARGV do_test
 195 #include <support/test-driver.c>