From ed8d5ffd0a14e84298a15ae2ec9b799010166b28 Mon Sep 17 00:00:00 2001 From: Siddhesh Poyarekar Date: Thu, 2 Feb 2017 15:48:06 +0530 Subject: 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. --- ChangeLog | 5 +++++ elf/tst-env-setuid-tunables.c | 9 +++++++++ sysdeps/generic/unsecvars.h | 7 +++++++ 3 files changed, 21 insertions(+) diff --git a/ChangeLog b/ChangeLog index aed8764272..a210e631f4 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,10 @@ 2017-02-02 Siddhesh Poyarekar + * 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. + [BZ #21073] * elf/dl-tunable-types.h (tunable_seclevel_t): New enum. * elf/dl-tunables.c (tunables_strdup): Remove. diff --git a/elf/tst-env-setuid-tunables.c b/elf/tst-env-setuid-tunables.c index a563f69972..a5f0a81ef3 100644 --- a/elf/tst-env-setuid-tunables.c +++ b/elf/tst-env-setuid-tunables.c @@ -36,6 +36,7 @@ test_child_tunables (void) { const char *val = getenv ("GLIBC_TUNABLES"); +#if HAVE_TUNABLES if (val != NULL && strcmp (val, CHILD_VALSTRING_VALUE) == 0) return 0; @@ -43,6 +44,14 @@ test_child_tunables (void) 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 diff --git a/sysdeps/generic/unsecvars.h b/sysdeps/generic/unsecvars.h index d5b8119c9c..a74083786e 100644 --- a/sysdeps/generic/unsecvars.h +++ b/sysdeps/generic/unsecvars.h @@ -1,9 +1,16 @@ +#if !HAVE_TUNABLES +# define GLIBC_TUNABLES_ENVVAR "GLIBC_TUNABLES\0" +#else +# define GLIBC_TUNABLES_ENVVAR +#endif + /* Environment variable to be removed for SUID programs. The names are all stuffed in a single string which means they have to be terminated with a '\0' explicitly. */ #define UNSECURE_ENVVARS \ "GCONV_PATH\0" \ "GETCONF_DIR\0" \ + GLIBC_TUNABLES_ENVVAR \ "HOSTALIASES\0" \ "LD_AUDIT\0" \ "LD_DEBUG\0" \ -- cgit v1.2.1