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/* Copyright (C) 2012-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/* Verify that correctly filter out unsafe environment variables defined
in unsecvars.h. */
#include <array_length.h>
#include <gnu/lib-names.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <support/check.h>
#include <support/support.h>
#include <support/test-driver.h>
#include <support/capture_subprocess.h>
static char SETGID_CHILD[] = "setgid-child";
#define FILTERED_VALUE "some-filtered-value"
#define UNFILTERED_VALUE "some-unfiltered-value"
/* It assumes no other programs is being profile with a library with same
SONAME using the default folder. */
#ifndef PROFILE_LIB
# define PROFILE_LIB "tst-sonamemove-runmod2.so"
#endif
#define LD_DEBUG_OUTPUT "/tmp/some-file"
struct envvar_t
{
const char *env;
const char *value;
};
/* That is not an extensible list of all filtered out environment
variables. */
static const struct envvar_t filtered_envvars[] =
{
{ "GLIBC_TUNABLES", FILTERED_VALUE },
{ "LD_AUDIT", FILTERED_VALUE },
{ "LD_LIBRARY_PATH", FILTERED_VALUE },
{ "LD_PRELOAD", FILTERED_VALUE },
{ "LD_PROFILE", PROFILE_LIB },
{ "MALLOC_ARENA_MAX", FILTERED_VALUE },
{ "MALLOC_PERTURB_", FILTERED_VALUE },
{ "MALLOC_TRACE", FILTERED_VALUE },
{ "MALLOC_TRIM_THRESHOLD_", FILTERED_VALUE },
{ "RES_OPTIONS", FILTERED_VALUE },
{ "LD_DEBUG", "all" },
{ "LD_DEBUG_OUTPUT", LD_DEBUG_OUTPUT },
{ "LD_WARN", FILTERED_VALUE },
{ "LD_VERBOSE", FILTERED_VALUE },
{ "LD_BIND_NOW", "0" },
{ "LD_BIND_NOT", "1" },
};
static const struct envvar_t unfiltered_envvars[] =
{
/* Non longer supported option. */
{ "LD_ASSUME_KERNEL", UNFILTERED_VALUE },
};
static void
unlink_ld_debug_output (pid_t pid)
{
char *output = xasprintf ("%s.%d", LD_DEBUG_OUTPUT, pid);
unlink (output);
free (output);
}
static int
test_child (void)
{
int ret = 0;
for (const struct envvar_t *e = filtered_envvars;
e != array_end (filtered_envvars);
e++)
{
const char *env = getenv (e->env);
if (env != NULL)
{
printf ("FAIL: filtered environment variable is not NULL: %s=%s\n",
e->env, env);
ret = 1;
}
}
for (const struct envvar_t *e = unfiltered_envvars;
e != array_end (unfiltered_envvars);
e++)
{
const char *env = getenv (e->env);
if (!(env != NULL && strcmp (env, e->value) == 0))
{
if (env == NULL)
printf ("FAIL: unfiltered environment variable %s is NULL\n",
e->env);
else
printf ("FAIL: unfiltered environment variable %s=%s != %s\n",
e->env, env, e->value);
ret = 1;
}
}
/* Also check if no profile file was created.
The parent sets LD_DEBUG_OUTPUT="/tmp/some-file"
which should be filtered. Then it falls back to "/var/tmp".
Note: LD_PROFILE is not supported for static binaries. */
{
char *profilepath = xasprintf ("/var/tmp/%s.profile", PROFILE_LIB);
if (!access (profilepath, R_OK))
{
printf ("FAIL: LD_PROFILE file at %s was created!\n", profilepath);
ret = 1;
}
free (profilepath);
}
return ret;
}
static int
do_test (int argc, char **argv)
{
/* For dynamic loader, the test requires --enable-hardcoded-path-in-tests so
the kernel sets the AT_SECURE on process initialization. */
if (argc >= 2 && strstr (argv[1], LD_SO) != 0)
FAIL_UNSUPPORTED ("dynamic test requires --enable-hardcoded-path-in-tests");
/* Setgid child process. */
if (argc == 2 && strcmp (argv[1], SETGID_CHILD) == 0)
{
pid_t ppid = getppid ();
if (getgid () == getegid ())
{
/* This can happen if the file system is mounted nosuid. */
unlink_ld_debug_output (ppid);
FAIL_UNSUPPORTED ("SGID failed: GID and EGID match (%jd)\n",
(intmax_t) getgid ());
}
int ret = test_child ();
unlink_ld_debug_output (ppid);
if (ret != 0)
exit (1);
return 0;
}
else
{
for (const struct envvar_t *e = filtered_envvars;
e != array_end (filtered_envvars);
e++)
setenv (e->env, e->value, 1);
for (const struct envvar_t *e = unfiltered_envvars;
e != array_end (unfiltered_envvars);
e++)
setenv (e->env, e->value, 1);
/* Ensure that the profile output does not exist from a previous run
(e.g. if test_dir, which defaults to /tmp, is mounted nosuid.)
Note: support_capture_subprogram_self_sgid creates the SGID binary
in test_dir. */
{
char *profilepath = xasprintf ("/var/tmp/%s.profile", PROFILE_LIB);
unlink (profilepath);
free (profilepath);
}
support_capture_subprogram_self_sgid (SETGID_CHILD);
return 0;
}
}
#define TEST_FUNCTION_ARGV do_test
#include <support/test-driver.c>
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