| /* |
| * Copyright (C) 2019 The Android Open Source Project |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
| * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
| * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| */ |
| |
| #include "heap_tagging.h" |
| #include "malloc_common.h" |
| #include "malloc_tagged_pointers.h" |
| |
| #include <bionic/pthread_internal.h> |
| #include <platform/bionic/malloc.h> |
| #include <sanitizer/hwasan_interface.h> |
| #include <sys/auxv.h> |
| |
| extern "C" void scudo_malloc_disable_memory_tagging(); |
| extern "C" void scudo_malloc_set_track_allocation_stacks(int); |
| |
| // Protected by `g_heap_tagging_lock`. |
| static HeapTaggingLevel heap_tagging_level = M_HEAP_TAGGING_LEVEL_NONE; |
| |
| void SetDefaultHeapTaggingLevel() { |
| #if defined(__aarch64__) |
| #if !__has_feature(hwaddress_sanitizer) |
| heap_tagging_level = __libc_shared_globals()->initial_heap_tagging_level; |
| #endif |
| |
| __libc_globals.mutate([](libc_globals* globals) { |
| switch (heap_tagging_level) { |
| case M_HEAP_TAGGING_LEVEL_TBI: |
| // Arrange for us to set pointer tags to POINTER_TAG, check tags on |
| // deallocation and untag when passing pointers to the allocator. |
| globals->heap_pointer_tag = (reinterpret_cast<uintptr_t>(POINTER_TAG) << TAG_SHIFT) | |
| (0xffull << CHECK_SHIFT) | (0xffull << UNTAG_SHIFT); |
| break; |
| case M_HEAP_TAGGING_LEVEL_SYNC: |
| case M_HEAP_TAGGING_LEVEL_ASYNC: |
| atomic_store(&globals->memtag_stack, __libc_shared_globals()->initial_memtag_stack); |
| break; |
| default: |
| break; |
| }; |
| }); |
| |
| #if defined(USE_SCUDO) |
| switch (heap_tagging_level) { |
| case M_HEAP_TAGGING_LEVEL_TBI: |
| case M_HEAP_TAGGING_LEVEL_NONE: |
| scudo_malloc_disable_memory_tagging(); |
| break; |
| case M_HEAP_TAGGING_LEVEL_SYNC: |
| scudo_malloc_set_track_allocation_stacks(1); |
| break; |
| default: |
| break; |
| } |
| #endif // USE_SCUDO |
| #endif // aarch64 |
| } |
| |
| static bool set_tcf_on_all_threads(int tcf) { |
| return android_run_on_all_threads( |
| [](void* arg) { |
| int tcf = *reinterpret_cast<int*>(arg); |
| int tagged_addr_ctrl = prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0); |
| if (tagged_addr_ctrl < 0) { |
| return false; |
| } |
| |
| tagged_addr_ctrl = (tagged_addr_ctrl & ~PR_MTE_TCF_MASK) | tcf; |
| if (prctl(PR_SET_TAGGED_ADDR_CTRL, tagged_addr_ctrl, 0, 0, 0) < 0) { |
| return false; |
| } |
| return true; |
| }, |
| &tcf); |
| } |
| |
| pthread_mutex_t g_heap_tagging_lock = PTHREAD_MUTEX_INITIALIZER; |
| |
| // Requires `g_heap_tagging_lock` to be held. |
| bool SetHeapTaggingLevel(HeapTaggingLevel tag_level) { |
| if (tag_level == heap_tagging_level) { |
| return true; |
| } |
| |
| switch (tag_level) { |
| case M_HEAP_TAGGING_LEVEL_NONE: |
| __libc_globals.mutate([](libc_globals* globals) { |
| if (heap_tagging_level == M_HEAP_TAGGING_LEVEL_TBI) { |
| // Preserve the untag mask (we still want to untag pointers when passing them to the |
| // allocator), but clear the fixed tag and the check mask, so that pointers are no longer |
| // tagged and checks no longer happen. |
| globals->heap_pointer_tag = static_cast<uintptr_t>(0xffull << UNTAG_SHIFT); |
| } |
| atomic_store(&globals->memtag_stack, false); |
| }); |
| |
| if (heap_tagging_level != M_HEAP_TAGGING_LEVEL_TBI) { |
| if (!set_tcf_on_all_threads(PR_MTE_TCF_NONE)) { |
| error_log("SetHeapTaggingLevel: set_tcf_on_all_threads failed"); |
| return false; |
| } |
| } |
| #if defined(USE_SCUDO) |
| scudo_malloc_disable_memory_tagging(); |
| #endif |
| break; |
| case M_HEAP_TAGGING_LEVEL_TBI: |
| case M_HEAP_TAGGING_LEVEL_ASYNC: |
| case M_HEAP_TAGGING_LEVEL_SYNC: |
| if (heap_tagging_level == M_HEAP_TAGGING_LEVEL_NONE) { |
| #if !__has_feature(hwaddress_sanitizer) |
| // Suppress the error message in HWASan builds. Apps can try to enable TBI (or even MTE |
| // modes) being unaware of HWASan, fail them silently. |
| error_log( |
| "SetHeapTaggingLevel: re-enabling tagging after it was disabled is not supported"); |
| #endif |
| return false; |
| } else if (tag_level == M_HEAP_TAGGING_LEVEL_TBI || |
| heap_tagging_level == M_HEAP_TAGGING_LEVEL_TBI) { |
| error_log("SetHeapTaggingLevel: switching between TBI and ASYNC/SYNC is not supported"); |
| return false; |
| } |
| |
| if (tag_level == M_HEAP_TAGGING_LEVEL_ASYNC) { |
| // When entering ASYNC mode, specify that we want to allow upgrading to SYNC by OR'ing in |
| // the SYNC flag. But if the kernel doesn't support specifying multiple TCF modes, fall back |
| // to specifying a single mode. |
| if (!set_tcf_on_all_threads(PR_MTE_TCF_ASYNC | PR_MTE_TCF_SYNC)) { |
| set_tcf_on_all_threads(PR_MTE_TCF_ASYNC); |
| } |
| #if defined(USE_SCUDO) |
| scudo_malloc_set_track_allocation_stacks(0); |
| #endif |
| } else if (tag_level == M_HEAP_TAGGING_LEVEL_SYNC) { |
| set_tcf_on_all_threads(PR_MTE_TCF_SYNC); |
| #if defined(USE_SCUDO) |
| scudo_malloc_set_track_allocation_stacks(1); |
| #endif |
| } |
| break; |
| default: |
| error_log("SetHeapTaggingLevel: unknown tagging level"); |
| return false; |
| } |
| |
| heap_tagging_level = tag_level; |
| info_log("SetHeapTaggingLevel: tag level set to %d", tag_level); |
| |
| return true; |
| } |
| |
| #ifdef __aarch64__ |
| static inline __attribute__((no_sanitize("memtag"))) void untag_memory(void* from, void* to) { |
| __asm__ __volatile__( |
| ".arch_extension mte\n" |
| "1:\n" |
| "stg %[Ptr], [%[Ptr]], #16\n" |
| "cmp %[Ptr], %[End]\n" |
| "b.lt 1b\n" |
| : [Ptr] "+&r"(from) |
| : [End] "r"(to) |
| : "memory"); |
| } |
| #endif |
| |
| #ifdef __aarch64__ |
| // 128Mb of stack should be enough for anybody. |
| static constexpr size_t kUntagLimit = 128 * 1024 * 1024; |
| #endif // __aarch64__ |
| |
| extern "C" __LIBC_HIDDEN__ __attribute__((no_sanitize("memtag"))) void memtag_handle_longjmp( |
| void* sp_dst __unused) { |
| #ifdef __aarch64__ |
| if (__libc_globals->memtag_stack) { |
| void* sp = __builtin_frame_address(0); |
| size_t distance = reinterpret_cast<uintptr_t>(sp_dst) - reinterpret_cast<uintptr_t>(sp); |
| if (distance > kUntagLimit) { |
| async_safe_fatal( |
| "memtag_handle_longjmp: stack adjustment too large! %p -> %p, distance %zx > %zx\n", sp, |
| sp_dst, distance, kUntagLimit); |
| } else { |
| untag_memory(sp, sp_dst); |
| } |
| } |
| #endif // __aarch64__ |
| |
| // We can use __has_feature here rather than __hwasan_handle_longjmp as a |
| // weak symbol because this is part of libc which is always sanitized for a |
| // hwasan enabled process. |
| #if __has_feature(hwaddress_sanitizer) |
| __hwasan_handle_longjmp(sp_dst); |
| #endif // __has_feature(hwaddress_sanitizer) |
| } |