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x86: Modularize sysdeps/x86/dl-cet.c
Improve readability and make maintenance easier for dl-feature.c by modularizing sysdeps/x86/dl-cet.c: 1. Support processors with: a. Only IBT. Or b. Only SHSTK. Or c. Both IBT and SHSTK. 2. Lock CET features only if IBT or SHSTK are enabled and are not enabled permissively.
This commit is contained in:
H.J. Lu
parent
1a23b39f9d
commit
c04035809a
@ -32,206 +32,310 @@
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# error GNU_PROPERTY_X86_FEATURE_1_SHSTK != X86_FEATURE_1_SHSTK
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#endif
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/* Check if object M is compatible with CET. */
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struct dl_cet_info
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{
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const char *program;
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/* Check how IBT and SHSTK should be enabled. */
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enum dl_x86_cet_control enable_ibt_type;
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enum dl_x86_cet_control enable_shstk_type;
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/* If IBT and SHSTK were previously enabled. */
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unsigned int feature_1_enabled;
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/* If IBT and SHSTK should be enabled. */
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unsigned int enable_feature_1;
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/* If there are any legacy shared object. */
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unsigned int feature_1_legacy;
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/* Which shared object is the first legacy shared object. */
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unsigned int feature_1_legacy_ibt;
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unsigned int feature_1_legacy_shstk;
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};
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/* Check if the object M and its dependencies are legacy object. */
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static void
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dl_check_legacy_object (struct link_map *m,
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struct dl_cet_info *info)
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{
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unsigned int i;
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struct link_map *l = NULL;
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i = m->l_searchlist.r_nlist;
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while (i-- > 0)
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{
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/* Check each shared object to see if IBT and SHSTK are enabled. */
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l = m->l_initfini[i];
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if (l->l_init_called)
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continue;
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#ifdef SHARED
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/* Skip check for ld.so since it has the features enabled. The
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features will be disabled later if they are not enabled in
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executable. */
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if (l == &GL(dl_rtld_map)
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|| l->l_real == &GL(dl_rtld_map)
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|| (info->program != NULL && l == m))
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continue;
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#endif
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/* IBT and SHSTK set only if enabled in executable and all DSOs.
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NB: cet_always_on is handled outside of the loop. */
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info->enable_feature_1 &= ((l->l_x86_feature_1_and
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& (GNU_PROPERTY_X86_FEATURE_1_IBT
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| GNU_PROPERTY_X86_FEATURE_1_SHSTK))
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| ~(GNU_PROPERTY_X86_FEATURE_1_IBT
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| GNU_PROPERTY_X86_FEATURE_1_SHSTK));
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if ((info->feature_1_legacy
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& GNU_PROPERTY_X86_FEATURE_1_IBT) == 0
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&& ((info->enable_feature_1
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& GNU_PROPERTY_X86_FEATURE_1_IBT)
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!= (info->feature_1_enabled
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& GNU_PROPERTY_X86_FEATURE_1_IBT)))
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{
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info->feature_1_legacy_ibt = i;
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info->feature_1_legacy |= GNU_PROPERTY_X86_FEATURE_1_IBT;
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}
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if ((info->feature_1_legacy
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& GNU_PROPERTY_X86_FEATURE_1_SHSTK) == 0
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&& ((info->enable_feature_1
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& GNU_PROPERTY_X86_FEATURE_1_SHSTK)
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!= (info->feature_1_enabled
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& GNU_PROPERTY_X86_FEATURE_1_SHSTK)))
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{
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info->feature_1_legacy_shstk = i;
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info->feature_1_legacy |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
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}
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}
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/* Handle cet_always_on. */
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if ((info->feature_1_enabled
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& GNU_PROPERTY_X86_FEATURE_1_IBT) != 0
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&& info->enable_ibt_type == cet_always_on)
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{
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info->feature_1_legacy &= ~GNU_PROPERTY_X86_FEATURE_1_IBT;
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info->enable_feature_1 |= GNU_PROPERTY_X86_FEATURE_1_IBT;
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}
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if ((info->feature_1_enabled
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& GNU_PROPERTY_X86_FEATURE_1_SHSTK) != 0
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&& info->enable_shstk_type == cet_always_on)
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{
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info->feature_1_legacy &= ~GNU_PROPERTY_X86_FEATURE_1_SHSTK;
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info->enable_feature_1 |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
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}
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}
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#ifdef SHARED
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/* Enable IBT and SHSTK only if they are enabled in executable. Set
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feature bits properly at the start of the program. */
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static void
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dl_cet_check_startup (struct link_map *m, struct dl_cet_info *info)
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{
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/* NB: IBT and SHSTK may be disabled by environment variable:
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GLIBC_TUNABLES=glibc.cpu.hwcaps=-IBT,-SHSTK.
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*/
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if (CPU_FEATURE_USABLE (IBT))
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{
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if (info->enable_ibt_type == cet_always_on)
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info->enable_feature_1 |= GNU_PROPERTY_X86_FEATURE_1_IBT;
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else
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info->enable_feature_1 &= ((m->l_x86_feature_1_and
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& GNU_PROPERTY_X86_FEATURE_1_IBT)
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| ~GNU_PROPERTY_X86_FEATURE_1_IBT);
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}
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else
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info->enable_feature_1 &= ~GNU_PROPERTY_X86_FEATURE_1_IBT;
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if (CPU_FEATURE_USABLE (SHSTK))
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{
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if (info->enable_shstk_type == cet_always_on)
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info->enable_feature_1 |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
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else
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info->enable_feature_1 &= ((m->l_x86_feature_1_and
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& GNU_PROPERTY_X86_FEATURE_1_SHSTK)
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| ~GNU_PROPERTY_X86_FEATURE_1_SHSTK);
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}
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else
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info->enable_feature_1 &= ~GNU_PROPERTY_X86_FEATURE_1_SHSTK;
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if (info->enable_feature_1 != 0)
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dl_check_legacy_object (m, info);
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unsigned int disable_feature_1
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= info->enable_feature_1 ^ info->feature_1_enabled;
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if (disable_feature_1 != 0)
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{
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/* Disable features in the kernel because of legacy objects or
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cet_always_off. */
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if (dl_cet_disable_cet (disable_feature_1) != 0)
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_dl_fatal_printf ("%s: can't disable x86 Features\n",
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info->program);
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/* Clear the disabled bits. Sync dl_x86_feature_1 and
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info->feature_1_enabled with info->enable_feature_1. */
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info->feature_1_enabled = info->enable_feature_1;
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GL(dl_x86_feature_1) = info->enable_feature_1;
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}
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if (HAS_CPU_FEATURE (IBT) || HAS_CPU_FEATURE (SHSTK))
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{
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/* Lock CET features only if IBT or SHSTK are enabled and are not
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enabled permissively. */
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unsigned int feature_1_lock = 0;
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if (((info->feature_1_enabled & GNU_PROPERTY_X86_FEATURE_1_IBT)
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!= 0)
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&& info->enable_ibt_type != cet_permissive)
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feature_1_lock |= GNU_PROPERTY_X86_FEATURE_1_IBT;
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if (((info->feature_1_enabled & GNU_PROPERTY_X86_FEATURE_1_SHSTK)
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!= 0)
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&& info->enable_shstk_type != cet_permissive)
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feature_1_lock |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
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if (feature_1_lock != 0
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&& dl_cet_lock_cet () != 0)
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_dl_fatal_printf ("%s: can't lock CET\n", info->program);
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}
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THREAD_SETMEM (THREAD_SELF, header.feature_1, GL(dl_x86_feature_1));
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}
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#endif
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/* Check feature bits when dlopening the shared object M. */
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static void
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dl_cet_check_dlopen (struct link_map *m, struct dl_cet_info *info)
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{
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/* Check if there are any legacy objects loaded. */
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if (info->enable_feature_1 != 0)
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{
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dl_check_legacy_object (m, info);
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/* Skip if there are no legacy shared objects loaded. */
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if (info->feature_1_legacy == 0)
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return;
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}
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unsigned int disable_feature_1 = 0;
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unsigned int legacy_obj = 0;
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const char *msg = NULL;
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if ((info->feature_1_enabled
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& GNU_PROPERTY_X86_FEATURE_1_IBT) != 0
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&& (info->feature_1_legacy
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& GNU_PROPERTY_X86_FEATURE_1_IBT) != 0)
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{
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if (info->enable_ibt_type != cet_permissive)
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{
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legacy_obj = info->feature_1_legacy_ibt;
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msg = N_("rebuild shared object with IBT support enabled");
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}
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else
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disable_feature_1 |= GNU_PROPERTY_X86_FEATURE_1_IBT;
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}
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/* Check the next feature only if there is no error. */
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if (msg == NULL
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&& (info->feature_1_enabled
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& GNU_PROPERTY_X86_FEATURE_1_SHSTK) != 0
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&& (info->feature_1_legacy
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& GNU_PROPERTY_X86_FEATURE_1_SHSTK) != 0)
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{
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if (info->enable_shstk_type != cet_permissive)
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{
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legacy_obj = info->feature_1_legacy_shstk;
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msg = N_("rebuild shared object with SHSTK support enabled");
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}
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else
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disable_feature_1 |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
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}
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/* If there is an error, long jump back to the caller. */
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if (msg != NULL)
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_dl_signal_error (0, m->l_initfini[legacy_obj]->l_name, "dlopen",
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msg);
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if (disable_feature_1 != 0)
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{
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int res = dl_cet_disable_cet (disable_feature_1);
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if (res)
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{
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if ((disable_feature_1
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& GNU_PROPERTY_X86_FEATURE_1_IBT) != 0)
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msg = N_("can't disable IBT");
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else
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msg = N_("can't disable SHSTK");
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/* Long jump back to the caller on error. */
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_dl_signal_error (-res, m->l_initfini[legacy_obj]->l_name,
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"dlopen", msg);
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}
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/* Clear the disabled bits in dl_x86_feature_1. */
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GL(dl_x86_feature_1) &= ~disable_feature_1;
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THREAD_SETMEM (THREAD_SELF, header.feature_1,
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GL(dl_x86_feature_1));
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}
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}
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static void
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dl_cet_check (struct link_map *m, const char *program)
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{
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/* Check how IBT should be enabled. */
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enum dl_x86_cet_control enable_ibt_type
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= GL(dl_x86_feature_control).ibt;
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/* Check how SHSTK should be enabled. */
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enum dl_x86_cet_control enable_shstk_type
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= GL(dl_x86_feature_control).shstk;
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struct dl_cet_info info;
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/* No legacy object check if both IBT and SHSTK are always on. */
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if (enable_ibt_type == cet_always_on
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&& enable_shstk_type == cet_always_on)
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/* Check how IBT and SHSTK should be enabled. */
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info.enable_ibt_type = GL(dl_x86_feature_control).ibt;
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info.enable_shstk_type = GL(dl_x86_feature_control).shstk;
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info.feature_1_enabled = GL(dl_x86_feature_1);
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/* No legacy object check if IBT and SHSTK are always on. */
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if (info.enable_ibt_type == cet_always_on
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&& info.enable_shstk_type == cet_always_on)
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{
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THREAD_SETMEM (THREAD_SELF, header.feature_1, GL(dl_x86_feature_1));
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#ifdef SHARED
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/* Set it only during startup. */
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if (program != NULL)
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THREAD_SETMEM (THREAD_SELF, header.feature_1,
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info.feature_1_enabled);
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#endif
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return;
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}
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/* Check if IBT is enabled by kernel. */
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bool ibt_enabled
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= (GL(dl_x86_feature_1) & GNU_PROPERTY_X86_FEATURE_1_IBT) != 0;
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/* Check if SHSTK is enabled by kernel. */
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bool shstk_enabled
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= (GL(dl_x86_feature_1) & GNU_PROPERTY_X86_FEATURE_1_SHSTK) != 0;
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/* Check if IBT and SHSTK were enabled by kernel. */
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if (info.feature_1_enabled == 0)
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return;
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if (ibt_enabled || shstk_enabled)
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{
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struct link_map *l = NULL;
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unsigned int ibt_legacy = 0, shstk_legacy = 0;
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bool found_ibt_legacy = false, found_shstk_legacy = false;
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info.program = program;
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/* Check if IBT and SHSTK are enabled in object. */
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bool enable_ibt = (ibt_enabled
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&& enable_ibt_type != cet_always_off);
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bool enable_shstk = (shstk_enabled
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&& enable_shstk_type != cet_always_off);
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if (program)
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{
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/* Enable IBT and SHSTK only if they are enabled in executable.
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NB: IBT and SHSTK may be disabled by environment variable:
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/* Check which features should be enabled. */
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info.enable_feature_1 = 0;
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if (info.enable_ibt_type != cet_always_off)
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info.enable_feature_1 |= (info.feature_1_enabled
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& GNU_PROPERTY_X86_FEATURE_1_IBT);
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if (info.enable_shstk_type != cet_always_off)
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info.enable_feature_1 |= (info.feature_1_enabled
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& GNU_PROPERTY_X86_FEATURE_1_SHSTK);
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GLIBC_TUNABLES=glibc.cpu.hwcaps=-IBT,-SHSTK
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*/
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enable_ibt &= (CPU_FEATURE_USABLE (IBT)
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&& (enable_ibt_type == cet_always_on
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|| (m->l_x86_feature_1_and
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& GNU_PROPERTY_X86_FEATURE_1_IBT) != 0));
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enable_shstk &= (CPU_FEATURE_USABLE (SHSTK)
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&& (enable_shstk_type == cet_always_on
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|| (m->l_x86_feature_1_and
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& GNU_PROPERTY_X86_FEATURE_1_SHSTK) != 0));
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}
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/* ld.so is CET-enabled by kernel. But shared objects may not
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support IBT nor SHSTK. */
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if (enable_ibt || enable_shstk)
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{
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unsigned int i;
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i = m->l_searchlist.r_nlist;
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while (i-- > 0)
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{
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/* Check each shared object to see if IBT and SHSTK are
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enabled. */
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l = m->l_initfini[i];
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if (l->l_init_called)
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continue;
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/* Start with no legacy objects. */
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info.feature_1_legacy = 0;
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info.feature_1_legacy_ibt = 0;
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info.feature_1_legacy_shstk = 0;
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#ifdef SHARED
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/* Skip CET check for ld.so since ld.so is CET-enabled.
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CET will be disabled later if CET isn't enabled in
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executable. */
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if (l == &GL(dl_rtld_map)
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|| l->l_real == &GL(dl_rtld_map)
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|| (program && l == m))
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continue;
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if (program)
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dl_cet_check_startup (m, &info);
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else
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#endif
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/* IBT is enabled only if it is enabled in executable as
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well as all shared objects. */
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enable_ibt &= (enable_ibt_type == cet_always_on
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|| (l->l_x86_feature_1_and
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& GNU_PROPERTY_X86_FEATURE_1_IBT) != 0);
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if (!found_ibt_legacy && enable_ibt != ibt_enabled)
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{
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found_ibt_legacy = true;
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ibt_legacy = i;
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}
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/* SHSTK is enabled only if it is enabled in executable as
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well as all shared objects. */
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enable_shstk &= (enable_shstk_type == cet_always_on
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|| (l->l_x86_feature_1_and
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& GNU_PROPERTY_X86_FEATURE_1_SHSTK) != 0);
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if (enable_shstk != shstk_enabled)
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{
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found_shstk_legacy = true;
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shstk_legacy = i;
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}
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}
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}
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bool cet_feature_changed = false;
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if (enable_ibt != ibt_enabled || enable_shstk != shstk_enabled)
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{
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if (!program)
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{
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if (enable_ibt_type != cet_permissive)
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{
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/* When IBT is enabled, we cannot dlopen a shared
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object without IBT. */
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if (found_ibt_legacy)
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_dl_signal_error (0,
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m->l_initfini[ibt_legacy]->l_name,
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"dlopen",
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N_("rebuild shared object with IBT support enabled"));
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}
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if (enable_shstk_type != cet_permissive)
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{
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/* When SHSTK is enabled, we cannot dlopen a shared
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object without SHSTK. */
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if (found_shstk_legacy)
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_dl_signal_error (0,
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m->l_initfini[shstk_legacy]->l_name,
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"dlopen",
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N_("rebuild shared object with SHSTK support enabled"));
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}
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if (enable_ibt_type != cet_permissive
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&& enable_shstk_type != cet_permissive)
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return;
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}
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/* Disable IBT and/or SHSTK if they are enabled by kernel, but
|
||||
disabled in executable or shared objects. */
|
||||
unsigned int cet_feature = 0;
|
||||
|
||||
if (!enable_ibt)
|
||||
cet_feature |= GNU_PROPERTY_X86_FEATURE_1_IBT;
|
||||
if (!enable_shstk)
|
||||
cet_feature |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
|
||||
|
||||
int res = dl_cet_disable_cet (cet_feature);
|
||||
if (res != 0)
|
||||
{
|
||||
if (program)
|
||||
_dl_fatal_printf ("%s: can't disable CET\n", program);
|
||||
else
|
||||
{
|
||||
if (found_ibt_legacy)
|
||||
l = m->l_initfini[ibt_legacy];
|
||||
else
|
||||
l = m->l_initfini[shstk_legacy];
|
||||
_dl_signal_error (-res, l->l_name, "dlopen",
|
||||
N_("can't disable CET"));
|
||||
}
|
||||
}
|
||||
|
||||
/* Clear the disabled bits in dl_x86_feature_1. */
|
||||
GL(dl_x86_feature_1) &= ~cet_feature;
|
||||
|
||||
cet_feature_changed = true;
|
||||
}
|
||||
|
||||
#ifdef SHARED
|
||||
if (program && (ibt_enabled || shstk_enabled))
|
||||
{
|
||||
if ((!ibt_enabled
|
||||
|| enable_ibt_type != cet_permissive)
|
||||
&& (!shstk_enabled
|
||||
|| enable_shstk_type != cet_permissive))
|
||||
{
|
||||
/* Lock CET if IBT or SHSTK is enabled in executable unless
|
||||
IBT or SHSTK is enabled permissively. */
|
||||
int res = dl_cet_lock_cet ();
|
||||
if (res != 0)
|
||||
_dl_fatal_printf ("%s: can't lock CET\n", program);
|
||||
}
|
||||
|
||||
/* Set feature_1 if IBT or SHSTK is enabled in executable. */
|
||||
cet_feature_changed = true;
|
||||
}
|
||||
#endif
|
||||
|
||||
if (cet_feature_changed)
|
||||
{
|
||||
unsigned int feature_1 = 0;
|
||||
if (enable_ibt)
|
||||
feature_1 |= GNU_PROPERTY_X86_FEATURE_1_IBT;
|
||||
if (enable_shstk)
|
||||
feature_1 |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
|
||||
struct pthread *self = THREAD_SELF;
|
||||
THREAD_SETMEM (self, header.feature_1, feature_1);
|
||||
}
|
||||
}
|
||||
dl_cet_check_dlopen (m, &info);
|
||||
}
|
||||
|
||||
void
|
||||
|
||||
Loading…
Reference in New Issue
Block a user