From 8b9e9c3c0bae497ad5e2d0ae2f333f62feddcc12 Mon Sep 17 00:00:00 2001 From: Siddhesh Poyarekar Date: Thu, 2 Feb 2017 15:46:01 +0530 Subject: tunables: Fix environment variable processing for setuid binaries (bz #21073) 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. --- elf/dl-tunables.h | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) (limited to 'elf/dl-tunables.h') diff --git a/elf/dl-tunables.h b/elf/dl-tunables.h index e07825c443..f33adfb359 100644 --- a/elf/dl-tunables.h +++ b/elf/dl-tunables.h @@ -41,11 +41,16 @@ struct _tunable tunable_val_t val; /* The value. */ const char *strval; /* The string containing the value, points into envp. */ - bool is_secure; /* Whether the tunable must be read - even for setuid binaries. Note that - even if the tunable is read, it may - not get used by the target module if - the value is considered unsafe. */ + tunable_seclevel_t security_level; /* Specify the security level for the + tunable with respect to AT_SECURE + programs. See description of + tunable_seclevel_t to see a + description of the values. + + Note that even if the tunable is + read, it may not get used by the + target module if the value is + considered unsafe. */ /* Compatibility elements. */ const char *env_alias; /* The compatibility environment variable name. */ -- cgit 1.4.1