tequilaOS/platform_bionic
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Make fork equivalent to vfork when HWASan or MTE stack tagging is enabled.

Browse source 
Bug: 274056091
Change-Id: Iac029ca6b0e26f57f20c0a54822b75e3cae67344
This commit is contained in:
Peter Collingbourne 2023-03-24 18:38:05 -07:00
parent 66542d6b97
commit b6a592b25b
8 changed files with 63 additions and 61 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

45
libc/arch-arm64/bionic/vfork.S
View file

@ -28,6 +28,7 @@
#include <platform/bionic/tls_defines.h>
#include <private/bionic_asm.h>
#include <private/bionic_asm_offsets.h>
#include <asm/signal.h>
#include <linux/sched.h>
@ -42,10 +43,29 @@ __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(vfork)
ldr w10, [x9, #20]
str w0, [x9, #20]
// Clear vfork_child_stack_bottom_.
str xzr, [x9, #776]
mov x0, #SIGCHLD
mov x0, #(CLONE_VM | CLONE_VFORK | SIGCHLD)
// If either HWASan or stack MTE is enabled, set up the clone() flags to
// make vfork() act like fork(). We don't call the atfork handlers, so we
// may deadlock if the child allocates, but we have seen badly written
// atfork handlers themselves cause deadlocks [1]. ndk_translation already
// implements vfork() as fork() without calling handlers, so we have some
// evidence that it isn't necessary to call them.
//
// POSIX.1 defines vfork() to have the same effect as fork() except that
// most behavior, including heap allocation, becomes undefined in the child,
// so we aren't violating POSIX by doing this.
//
// [1] https://cs.android.com/android/platform/superproject/+/master:system/extras/simpleperf/app_api/cpp/simpleperf.cpp;drc=788fa4183441f4977ddbd5a055e42a7fe7691d21;l=308
#if !__has_feature(hwaddress_sanitizer)
// if (!__libc_globals->memtag_stack) x0 |= CLONE_VM | CLONE_VFORK;
adrp x1, __libc_globals + OFFSETOF_libc_globals_memtag_stack
ldrb w1, [x1, :lo12:__libc_globals + OFFSETOF_libc_globals_memtag_stack]
cbnz w1, 1f
orr x0, x0, #CLONE_VM
orr x0, x0, #CLONE_VFORK
1:
#endif
mov x1, xzr
mov x2, xzr
mov x3, xzr
@ -62,25 +82,6 @@ __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(vfork)
cneg x0, x0, hi
b.hi __set_errno_internal
// Clean up stack shadow in the parent process.
// https://github.com/google/sanitizers/issues/925
paciasp
.cfi_negate_ra_state
stp x0, x30, [sp, #-16]!
.cfi_adjust_cfa_offset 16
.cfi_rel_offset x0, 0
.cfi_rel_offset x30, 8
add x0, sp, #16
bl memtag_handle_vfork
ldp x0, x30, [sp], #16
.cfi_adjust_cfa_offset -16
.cfi_restore x0
.cfi_restore x30
autiasp
.cfi_negate_ra_state
.L_exit:
ret
END(vfork)

1
libc/bionic/exec.cpp
View file

@ -186,6 +186,5 @@ int fexecve(int fd, char* const* argv, char* const* envp) {
__attribute__((no_sanitize("memtag"))) int execve(const char* pathname, char* const* argv,
char* const* envp) {
__get_thread()->vfork_child_stack_bottom = __builtin_frame_address(0);
return __execve(pathname, argv, envp);
}

1
libc/bionic/exit.cpp
View file

@ -37,7 +37,6 @@ extern "C" void __cxa_thread_finalize();
extern "C" __noreturn void __exit_group(int status);
__attribute__((no_sanitize("memtag"))) void _exit(int status) {
__get_thread()->vfork_child_stack_bottom = __builtin_frame_address(0);
__exit_group(status);
}

26
libc/bionic/heap_tagging.cpp
View file

@ -212,29 +212,3 @@ extern "C" __LIBC_HIDDEN__ __attribute__((no_sanitize("memtag"))) void memtag_ha
__hwasan_handle_longjmp(sp_dst);
#endif // __has_feature(hwaddress_sanitizer)
}
extern "C" __LIBC_HIDDEN__ __attribute__((no_sanitize("memtag"), no_sanitize("hwaddress"))) void
memtag_handle_vfork(void* sp __unused) {
#ifdef __aarch64__
if (__libc_globals->memtag_stack) {
void* child_sp = __get_thread()->vfork_child_stack_bottom;
__get_thread()->vfork_child_stack_bottom = nullptr;
if (child_sp) {
size_t distance = reinterpret_cast<uintptr_t>(sp) - reinterpret_cast<uintptr_t>(child_sp);
if (distance > kUntagLimit) {
async_safe_fatal(
"memtag_handle_vfork: stack adjustment too large! %p -> %p, distance %zx > %zx\n",
child_sp, sp, distance, kUntagLimit);
} else {
untag_memory(child_sp, sp);
}
} else {
async_safe_fatal("memtag_handle_vfork: child SP unknown\n");
}
}
#endif // __aarch64__
#if __has_feature(hwaddress_sanitizer)
__hwasan_handle_vfork(sp);
#endif // __has_feature(hwaddress_sanitizer)
}

7
libc/bionic/pthread_internal.h
View file

@ -173,13 +173,6 @@ class pthread_internal_t {
bionic_tls* bionic_tls;
int errno_value;
// The last observed value of SP in a vfork child process.
// The part of the stack between this address and the value of SP when the vfork parent process
// regains control may have stale MTE tags and needs cleanup. This field is only meaningful while
// the parent is waiting for the vfork child to return control by calling either exec*() or
// exit().
void* vfork_child_stack_bottom;
};
struct ThreadMapping {

33
libc/private/bionic_asm_offsets.h Normal file
View file

@ -0,0 +1,33 @@
/*
* Copyright (C) 2023 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.
*/
#pragma once
#ifdef __aarch64__
#define OFFSETOF_libc_globals_memtag_stack 80
#endif

5
libc/private/bionic_globals.h
View file

@ -38,6 +38,7 @@
#include "private/WriteProtected.h"
#include "private/bionic_allocator.h"
#include "private/bionic_asm_offsets.h"
#include "private/bionic_elf_tls.h"
#include "private/bionic_fdsan.h"
#include "private/bionic_malloc_dispatch.h"
@ -65,6 +66,10 @@ struct libc_globals {
MallocDispatch malloc_dispatch_table;
};
#ifdef __aarch64__
static_assert(OFFSETOF_libc_globals_memtag_stack == offsetof(libc_globals, memtag_stack));
#endif
__LIBC_HIDDEN__ extern WriteProtected<libc_globals> __libc_globals;
struct abort_msg_t;

6
tests/struct_layout_test.cpp
View file

@ -30,7 +30,7 @@ void tests(CheckSize check_size, CheckOffset check_offset) {
#define CHECK_OFFSET(name, field, offset) \
check_offset(#name, #field, offsetof(name, field), offset);
#ifdef __LP64__
CHECK_SIZE(pthread_internal_t, 784);
CHECK_SIZE(pthread_internal_t, 776);
CHECK_OFFSET(pthread_internal_t, next, 0);
CHECK_OFFSET(pthread_internal_t, prev, 8);
CHECK_OFFSET(pthread_internal_t, tid, 16);
@ -55,7 +55,6 @@ void tests(CheckSize check_size, CheckOffset check_offset) {
CHECK_OFFSET(pthread_internal_t, dlerror_buffer, 248);
CHECK_OFFSET(pthread_internal_t, bionic_tls, 760);
CHECK_OFFSET(pthread_internal_t, errno_value, 768);
CHECK_OFFSET(pthread_internal_t, vfork_child_stack_bottom, 776);
CHECK_SIZE(bionic_tls, 12200);
CHECK_OFFSET(bionic_tls, key_data, 0);
CHECK_OFFSET(bionic_tls, locale, 2080);
@ -73,7 +72,7 @@ void tests(CheckSize check_size, CheckOffset check_offset) {
CHECK_OFFSET(bionic_tls, bionic_systrace_disabled, 12193);
CHECK_OFFSET(bionic_tls, padding, 12194);
#else
CHECK_SIZE(pthread_internal_t, 672);
CHECK_SIZE(pthread_internal_t, 668);
CHECK_OFFSET(pthread_internal_t, next, 0);
CHECK_OFFSET(pthread_internal_t, prev, 4);
CHECK_OFFSET(pthread_internal_t, tid, 8);
@ -98,7 +97,6 @@ void tests(CheckSize check_size, CheckOffset check_offset) {
CHECK_OFFSET(pthread_internal_t, dlerror_buffer, 148);
CHECK_OFFSET(pthread_internal_t, bionic_tls, 660);
CHECK_OFFSET(pthread_internal_t, errno_value, 664);
CHECK_OFFSET(pthread_internal_t, vfork_child_stack_bottom, 668);
CHECK_SIZE(bionic_tls, 11080);
CHECK_OFFSET(bionic_tls, key_data, 0);
CHECK_OFFSET(bionic_tls, locale, 1040);