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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.
81 lines
2.2 KiB
Plaintext
81 lines
2.2 KiB
Plaintext
# 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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# Allowed attributes for tunables:
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#
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# type: Defaults to STRING
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# minval: Optional minimum acceptable value
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# maxval: Optional maximum acceptable value
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# env_alias: An alias environment variable
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# security_level: Specify security level of the tunable. Valid values are:
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#
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# SXID_ERASE: (default) Don't read for AT_SECURE binaries and
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# removed so that child processes can't read it.
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# SXID_IGNORE: Don't read for AT_SECURE binaries, but retained for
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# non-AT_SECURE subprocesses.
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# SXID_NONE: Read all the time.
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glibc {
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malloc {
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check {
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type: INT_32
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minval: 0
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maxval: 3
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env_alias: MALLOC_CHECK_
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}
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top_pad {
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type: SIZE_T
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env_alias: MALLOC_TOP_PAD_
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security_level: SXID_IGNORE
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}
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perturb {
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type: INT_32
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minval: 0
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maxval: 0xff
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env_alias: MALLOC_PERTURB_
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security_level: SXID_IGNORE
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}
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mmap_threshold {
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type: SIZE_T
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env_alias: MALLOC_MMAP_THRESHOLD_
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security_level: SXID_IGNORE
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}
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trim_threshold {
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type: SIZE_T
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env_alias: MALLOC_TRIM_THRESHOLD_
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security_level: SXID_IGNORE
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}
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mmap_max {
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type: INT_32
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env_alias: MALLOC_MMAP_MAX_
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security_level: SXID_IGNORE
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}
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arena_max {
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type: SIZE_T
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env_alias: MALLOC_ARENA_MAX
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minval: 1
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security_level: SXID_IGNORE
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}
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arena_test {
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type: SIZE_T
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env_alias: MALLOC_ARENA_TEST
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minval: 1
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security_level: SXID_IGNORE
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}
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}
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}
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