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Merge changes If42905f3,Id351a993,I8a082fd0

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* changes:
  fdtrack: don't do anything while vforked.
  fdsan: don't do anything when vforked.
  Track whether a thread is currently vforked.
This commit is contained in:
Treehugger Robot 2020-05-12 07:04:58 +00:00 committed by Gerrit Code Review
commit e3bc50d44f
10 changed files with 152 additions and 15 deletions
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14
libc/arch-arm/bionic/vfork.S
View file

@ -31,17 +31,27 @@
ENTRY(vfork)
__BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(vfork)
// __get_tls()[TLS_SLOT_THREAD_ID]->cached_pid_ = 0
// r3 = &__get_tls()[TLS_SLOT_THREAD_ID]
mrc p15, 0, r3, c13, c0, 3
ldr r3, [r3, #(TLS_SLOT_THREAD_ID * 4)]
mov r0, #0
// Set cached_pid_ to 0, vforked_ to 1, and stash the previous value.
mov r0, #0x80000000
ldr r1, [r3, #12]
str r0, [r3, #12]
mov ip, r7
ldr r7, =__NR_vfork
swi #0
mov r7, ip
teq r0, #0
bxeq lr
// rc != 0: reset cached_pid_ and vforked_.
str r1, [r3, #12]
cmn r0, #(MAX_ERRNO + 1)
bxls lr
neg r0, r0
b __set_errno_internal

16
libc/arch-arm64/bionic/vfork.S
View file

@ -36,10 +36,14 @@
ENTRY(vfork)
__BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(vfork)
// __get_tls()[TLS_SLOT_THREAD_ID]->cached_pid_ = 0
mrs x0, tpidr_el0
ldr x0, [x0, #(TLS_SLOT_THREAD_ID * 8)]
str wzr, [x0, #20]
// x9 = __get_tls()[TLS_SLOT_THREAD_ID]
mrs x9, tpidr_el0
ldr x9, [x9, #(TLS_SLOT_THREAD_ID * 8)]
// Set cached_pid_ to 0, vforked_ to 1, and stash the previous value.
mov w0, #0x80000000
ldr w10, [x9, #20]
str w0, [x9, #20]
mov x0, #(CLONE_VM | CLONE_VFORK | SIGCHLD)
mov x1, xzr
@ -50,6 +54,10 @@ __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(vfork)
mov x8, __NR_clone
svc #0
cbz x0, .L_exit
// rc != 0: reset cached_pid_ and vforked_.
str w10, [x9, #20]
cmn x0, #(MAX_ERRNO + 1)
cneg x0, x0, hi
b.hi __set_errno_internal

16
libc/arch-x86/bionic/vfork.S
View file

@ -37,13 +37,25 @@ __BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(vfork)
.cfi_adjust_cfa_offset 4
.cfi_rel_offset ecx, 0
// __get_tls()[TLS_SLOT_THREAD_ID]->cached_pid_ = 0
// Set cached_pid_ to 0, vforked_ to 1, and stash the previous value.
movl %gs:0, %eax
movl (TLS_SLOT_THREAD_ID * 4)(%eax), %eax
movl $0, 12(%eax)
movl 12(%eax), %edx
movl $0x80000000, 12(%eax)
movl $__NR_vfork, %eax
int $0x80
test %eax, %eax
jz 1f
// rc != 0: restore the previous cached_pid_/vforked_ values.
pushl %ecx
movl %gs:0, %ecx
movl (TLS_SLOT_THREAD_ID * 4)(%ecx), %ecx
movl %edx, 12(%ecx)
popl %ecx
cmpl $-MAX_ERRNO, %eax
jb 1f
negl %eax

16
libc/arch-x86_64/bionic/vfork.S
View file

@ -35,14 +35,22 @@ ENTRY(vfork)
__BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(vfork)
popq %rdi // Grab the return address.
// __get_tls()[TLS_SLOT_THREAD_ID]->cached_pid_ = 0
mov %fs:0, %rax
mov (TLS_SLOT_THREAD_ID * 8)(%rax), %rax
movl $0, 20(%rax)
// Set cached_pid_ to 0, vforked_ to 1, and stash the previous value.
mov %fs:0, %r8
mov (TLS_SLOT_THREAD_ID * 8)(%r8), %r8
movl 20(%r8), %r9d
movl $0x80000000, 20(%r8)
movl $__NR_vfork, %eax
syscall
pushq %rdi // Restore the return address.
test %eax, %eax
jz 1f
// rc != 0: restore the previous cached_pid_/vforked_ values.
movl %r9d, 20(%r8)
cmpq $-MAX_ERRNO, %rax
jb 1f
negl %eax

12
libc/bionic/fdsan.cpp
View file

@ -246,6 +246,10 @@ uint64_t android_fdsan_get_tag_value(uint64_t tag) {
}
int android_fdsan_close_with_tag(int fd, uint64_t expected_tag) {
if (__get_thread()->is_vforked()) {
return __close(fd);
}
FDTRACK_CLOSE(fd);
FdEntry* fde = GetFdEntry(fd);
if (!fde) {
@ -296,6 +300,10 @@ uint64_t android_fdsan_get_owner_tag(int fd) {
}
void android_fdsan_exchange_owner_tag(int fd, uint64_t expected_tag, uint64_t new_tag) {
if (__get_thread()->is_vforked()) {
return;
}
FdEntry* fde = GetFdEntry(fd);
if (!fde) {
return;
@ -332,6 +340,10 @@ android_fdsan_error_level android_fdsan_get_error_level() {
}
android_fdsan_error_level android_fdsan_set_error_level(android_fdsan_error_level new_level) {
if (__get_thread()->is_vforked()) {
return android_fdsan_get_error_level();
}
return atomic_exchange(&GetFdTable().error_level, new_level);
}

5
libc/bionic/pthread_internal.h
View file

@ -70,9 +70,12 @@ class pthread_internal_t {
pid_t tid;
private:
pid_t cached_pid_;
uint32_t cached_pid_ : 31;
uint32_t vforked_ : 1;
public:
bool is_vforked() { return vforked_; }
pid_t invalidate_cached_pid() {
pid_t old_value;
get_cached_pid(&old_value);

6
libc/private/bionic_fdtrack.h
View file

@ -47,7 +47,8 @@ extern "C" _Atomic(android_fdtrack_hook_t) __android_fdtrack_hook;
#define FDTRACK_CREATE_NAME(name, fd_value) \
({ \
int __fd = (fd_value); \
if (__fd != -1 && __predict_false(__android_fdtrack_hook)) { \
if (__fd != -1 && __predict_false(__android_fdtrack_hook) && \
!__predict_false(__get_thread()->is_vforked())) { \
bionic_tls& tls = __get_bionic_tls(); \
/* fdtrack_disabled is only true during reentrant calls. */ \
if (!__predict_false(tls.fdtrack_disabled)) { \
@ -76,7 +77,8 @@ extern "C" _Atomic(android_fdtrack_hook_t) __android_fdtrack_hook;
#define FDTRACK_CLOSE(fd_value) \
({ \
int __fd = (fd_value); \
if (__fd != -1 && __predict_false(__android_fdtrack_hook)) { \
if (__fd != -1 && __predict_false(__android_fdtrack_hook) && \
!__predict_false(__get_thread()->is_vforked())) { \
bionic_tls& tls = __get_bionic_tls(); \
if (!__predict_false(tls.fdtrack_disabled)) { \
int saved_errno = errno; \

19
tests/fdsan_test.cpp
View file

@ -23,6 +23,7 @@
#include <fcntl.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#if defined(__BIONIC__)
#include <android/fdsan.h>
@ -192,3 +193,21 @@ TEST_F(FdsanTest, unique_fd_unowned_close_after_move) {
EXPECT_FDSAN_DEATH(close(fd_moved.get()), "expected to be unowned, actually owned by unique_fd");
#endif
}
TEST_F(FdsanTest, vfork) {
android::base::unique_fd fd(open("/dev/null", O_RDONLY));
pid_t rc = vfork();
ASSERT_NE(-1, rc);
if (rc == 0) {
close(fd.get());
_exit(0);
}
int status;
pid_t wait_result = waitpid(rc, &status, 0);
ASSERT_EQ(wait_result, rc);
ASSERT_TRUE(WIFEXITED(status));
ASSERT_EQ(0, WEXITSTATUS(status));
}

20
tests/fdtrack_test.cpp
View file

@ -289,4 +289,24 @@ FDTRACK_TEST(recvmsg, ({
ASSERT_EQ(3, ReceiveFileDescriptors(sockets[1], buf, sizeof(buf), &received_fd));
received_fd.release();
}));
FDTRACK_TEST_NAME(vfork, "open", ({
int fd = open("/dev/null", O_RDONLY);
pid_t rc = vfork();
ASSERT_NE(-1, rc);
if (rc == 0) {
close(fd);
_exit(0);
}
int status;
pid_t wait_result = waitpid(rc, &status, 0);
ASSERT_EQ(wait_result, rc);
ASSERT_TRUE(WIFEXITED(status));
ASSERT_EQ(0, WEXITSTATUS(status));
fd;
}));
// clang-format on

43
tests/unistd_test.cpp
View file

@ -41,6 +41,10 @@
#include "private/get_cpu_count_from_string.h"
#if defined(__BIONIC__)
#include "bionic/pthread_internal.h"
#endif
#if defined(NOFORTIFY)
#define UNISTD_TEST unistd_nofortify
#define UNISTD_DEATHTEST unistd_nofortify_DeathTest
@ -431,6 +435,45 @@ TEST(UNISTD_TEST, syncfs) {
TestSyncFunction(syncfs);
}
TEST(UNISTD_TEST, vfork) {
#if defined(__BIONIC__)
pthread_internal_t* self = __get_thread();
pid_t cached_pid;
ASSERT_TRUE(self->get_cached_pid(&cached_pid));
ASSERT_EQ(syscall(__NR_getpid), cached_pid);
ASSERT_FALSE(self->is_vforked());
pid_t rc = vfork();
ASSERT_NE(-1, rc);
if (rc == 0) {
if (self->get_cached_pid(&cached_pid)) {
const char* error = "__get_thread()->cached_pid_ set after vfork\n";
write(STDERR_FILENO, error, strlen(error));
_exit(1);
}
if (!self->is_vforked()) {
const char* error = "__get_thread()->vforked_ not set after vfork\n";
write(STDERR_FILENO, error, strlen(error));
_exit(1);
}
_exit(0);
} else {
ASSERT_TRUE(self->get_cached_pid(&cached_pid));
ASSERT_EQ(syscall(__NR_getpid), cached_pid);
ASSERT_FALSE(self->is_vforked());
int status;
pid_t wait_result = waitpid(rc, &status, 0);
ASSERT_EQ(wait_result, rc);
ASSERT_TRUE(WIFEXITED(status));
ASSERT_EQ(0, WEXITSTATUS(status));
}
#endif
}
static void AssertGetPidCorrect() {
// The loop is just to make manual testing/debugging with strace easier.
pid_t getpid_syscall_result = syscall(__NR_getpid);