glibc/elf/tst-env-setuid-tunables.c
Siddhesh Poyarekar ed8d5ffd0a Drop GLIBC_TUNABLES for setxid programs when tunables is disabled (bz #21073)
A setxid program that uses a glibc with tunables disabled may pass on
GLIBC_TUNABLES as is to its child processes.  If the child process
ends up using a different glibc that has tunables enabled, it will end
up getting access to unsafe tunables.  To fix this, remove
GLIBC_TUNABLES from the environment for setxid process.

	* sysdeps/generic/unsecvars.h: Add GLIBC_TUNABLES.
	* elf/tst-env-setuid-tunables.c
	(test_child_tunables)[!HAVE_TUNABLES]: Verify that
	GLIBC_TUNABLES is removed in a setgid process.
2017-02-02 15:50:24 +05:30

70 lines
1.9 KiB
C

/* Copyright (C) 2017 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
<http://www.gnu.org/licenses/>. */
/* Verify that tunables correctly filter out unsafe tunables like
glibc.malloc.check and glibc.malloc.mmap_threshold but also retain
glibc.malloc.mmap_threshold in an unprivileged child. */
#define test_parent test_parent_tunables
#define test_child test_child_tunables
static int test_child_tunables (void);
static int test_parent_tunables (void);
#include "tst-env-setuid.c"
#define CHILD_VALSTRING_VALUE "glibc.malloc.mmap_threshold=4096"
#define PARENT_VALSTRING_VALUE \
"glibc.malloc.check=2:glibc.malloc.mmap_threshold=4096"
static int
test_child_tunables (void)
{
const char *val = getenv ("GLIBC_TUNABLES");
#if HAVE_TUNABLES
if (val != NULL && strcmp (val, CHILD_VALSTRING_VALUE) == 0)
return 0;
if (val != NULL)
printf ("Unexpected GLIBC_TUNABLES VALUE %s\n", val);
return 1;
#else
if (val != NULL)
{
printf ("GLIBC_TUNABLES not cleared\n");
return 1;
}
return 0;
#endif
}
static int
test_parent_tunables (void)
{
const char *val = getenv ("GLIBC_TUNABLES");
if (val != NULL && strcmp (val, PARENT_VALSTRING_VALUE) == 0)
return 0;
if (val != NULL)
printf ("Unexpected GLIBC_TUNABLES VALUE %s\n", val);
return 1;
}