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From a014cecd82b71b70a6a843e250e06b541ad524f7 Mon Sep 17 00:00:00 2001
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From: Florian Weimer <fweimer@redhat.com>
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Date: Thu, 15 Oct 2015 09:23:07 +0200
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Subject: [PATCH] Always enable pointer guard [BZ #18928]
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Honoring the LD_POINTER_GUARD environment variable in AT_SECURE mode
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has security implications. This commit enables pointer guard
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unconditionally, and the environment variable is now ignored.
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[BZ #18928]
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* sysdeps/generic/ldsodefs.h (struct rtld_global_ro): Remove
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_dl_pointer_guard member.
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* elf/rtld.c (_rtld_global_ro): Remove _dl_pointer_guard
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initializer.
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(security_init): Always set up pointer guard.
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(process_envvars): Do not process LD_POINTER_GUARD.
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diff -rup a/elf/rtld.c b/elf/rtld.c
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--- a/elf/rtld.c 2017-03-06 14:38:55.000000000 -0500
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+++ b/elf/rtld.c 2017-03-06 14:41:19.502556336 -0500
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@@ -160,7 +160,6 @@ struct rtld_global_ro _rtld_global_ro at
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._dl_hwcap_mask = HWCAP_IMPORTANT,
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._dl_lazy = 1,
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._dl_fpu_control = _FPU_DEFAULT,
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- ._dl_pointer_guard = 1,
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._dl_pagesize = EXEC_PAGESIZE,
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._dl_inhibit_cache = 0,
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@@ -844,15 +843,12 @@ security_init (void)
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#endif
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/* Set up the pointer guard as well, if necessary. */
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- if (GLRO(dl_pointer_guard))
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- {
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- uintptr_t pointer_chk_guard = _dl_setup_pointer_guard (_dl_random,
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- stack_chk_guard);
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+ uintptr_t pointer_chk_guard
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+ = _dl_setup_pointer_guard (_dl_random, stack_chk_guard);
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#ifdef THREAD_SET_POINTER_GUARD
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- THREAD_SET_POINTER_GUARD (pointer_chk_guard);
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+ THREAD_SET_POINTER_GUARD (pointer_chk_guard);
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#endif
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- __pointer_chk_guard_local = pointer_chk_guard;
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- }
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+ __pointer_chk_guard_local = pointer_chk_guard;
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/* We do not need the _dl_random value anymore. The less
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information we leave behind, the better, so clear the
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@@ -2599,9 +2595,6 @@ process_envvars (enum mode *modep)
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GLRO(dl_use_load_bias) = envline[14] == '1' ? -1 : 0;
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break;
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}
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-
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- if (memcmp (envline, "POINTER_GUARD", 13) == 0)
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- GLRO(dl_pointer_guard) = envline[14] != '0';
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break;
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case 14:
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diff -rup a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
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--- a/sysdeps/generic/ldsodefs.h 2017-03-06 14:38:57.000000000 -0500
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+++ b/sysdeps/generic/ldsodefs.h 2017-03-06 14:41:19.506556361 -0500
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@@ -588,9 +588,6 @@ struct rtld_global_ro
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/* List of auditing interfaces. */
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struct audit_ifaces *_dl_audit;
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unsigned int _dl_naudit;
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-
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- /* 0 if internal pointer values should not be guarded, 1 if they should. */
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- EXTERN int _dl_pointer_guard;
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};
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# define __rtld_global_attribute__
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# if IS_IN (rtld)
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