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Florian Weimer pointed out that we have three different kinds of environment variables (and hence tunables): 1. Variables that are removed for setxid processes 2. Variables that are ignored in setxid processes but is passed on to child processes 3. Variables that are passed on to child processes all the time Tunables currently only does (2) and (3) when it should be doing (1) for MALLOC_CHECK_. This patch enhances the is_secure flag in tunables to an enum value that can specify which of the above three categories the tunable (and its envvar alias) belongs to. The default is for tunables to be in (1). Hence, all of the malloc tunables barring MALLOC_CHECK_ are explicitly specified to belong to category (2). There were discussions around abolishing category (2) completely but we can do that as a separate exercise in 2.26. Tested on x86_64 to verify that there are no regressions. [BZ #21073] * elf/dl-tunable-types.h (tunable_seclevel_t): New enum. * elf/dl-tunables.c (tunables_strdup): Remove. (get_next_env): Also return the previous envp. (parse_tunables): Erase tunables of category TUNABLES_SECLEVEL_SXID_ERASE. (maybe_enable_malloc_check): Make MALLOC_CHECK_ TUNABLE_SECLEVEL_NONE if /etc/setuid-debug is accessible. (__tunables_init)[TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring]: Update GLIBC_TUNABLES envvar after parsing. [TUNABLES_FRONTEND != TUNABLES_FRONTEND_valstring]: Erase tunable envvars of category TUNABLES_SECLEVEL_SXID_ERASE. * elf/dl-tunables.h (struct _tunable): Change member is_secure to security_level. * elf/dl-tunables.list: Add security_level annotations for all tunables. * scripts/gen-tunables.awk: Recognize and generate enum values for security_level. * elf/tst-env-setuid.c: New test case. * elf/tst-env-setuid-tunables: new test case. * elf/Makefile (tests-static): Add them.
62 lines
1.7 KiB
C
62 lines
1.7 KiB
C
/* Tunable type information.
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Copyright (C) 2016-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _TUNABLE_TYPES_H_
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# define _TUNABLE_TYPES_H_
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#include <stddef.h>
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typedef void (*tunable_callback_t) (void *);
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typedef enum
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{
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TUNABLE_TYPE_INT_32,
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TUNABLE_TYPE_SIZE_T,
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TUNABLE_TYPE_STRING
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} tunable_type_code_t;
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typedef struct
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{
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tunable_type_code_t type_code;
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int64_t min;
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int64_t max;
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} tunable_type_t;
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typedef union
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{
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int64_t numval;
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const char *strval;
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} tunable_val_t;
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/* Security level for tunables. This decides what to do with individual
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tunables for AT_SECURE binaries. */
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typedef enum
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{
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/* Erase the tunable for AT_SECURE binaries so that child processes don't
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read it. */
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TUNABLE_SECLEVEL_SXID_ERASE = 0,
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/* Ignore the tunable for AT_SECURE binaries, but don't erase it, so that
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child processes can read it. */
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TUNABLE_SECLEVEL_SXID_IGNORE = 1,
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/* Read the tunable. */
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TUNABLE_SECLEVEL_NONE = 2,
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} tunable_seclevel_t;
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#endif
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