Add runtime FORTIFY support

Gingerbread libc.a missing symbols
This commit is contained in:
topjohnwu 2022-01-31 01:49:37 -08:00
parent 70415a396a
commit 9fa096c6f4
3 changed files with 113 additions and 6 deletions

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@ -11,12 +11,6 @@ ifndef B_SHARED
# Fix static variables' ctor/dtor when using LTO # Fix static variables' ctor/dtor when using LTO
# See: https://github.com/android/ndk/issues/1461 # See: https://github.com/android/ndk/issues/1461
APP_LDFLAGS += -T jni/lto_fix.lds APP_LDFLAGS += -T jni/lto_fix.lds
ifneq ($(TARGET_ARCH),arm64)
ifneq ($(TARGET_ARCH),x86_64)
# Disable fortify on static 32-bit targets
APP_CFLAGS += -D_FORTIFY_SOURCE=0 -Wno-macro-redefined
endif
endif
endif endif
# Busybox should use stock libc.a # Busybox should use stock libc.a

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@ -0,0 +1,110 @@
// Original source: https://android.googlesource.com/platform/bionic/+/master/libc/bionic/fortify.cpp
// License: AOSP, full copyright notice please check original source
#include <sys/stat.h>
#include <fcntl.h>
#include "logging.hpp"
#undef _FORTIFY_SOURCE
static inline __noreturn __printflike(1, 2) void __fortify_fatal(const char* fmt, ...) {
va_list args;
va_start(args, fmt);
log_cb.e(fmt, args);
va_end(args);
abort();
}
static inline void __check_count(const char* fn, const char* identifier, size_t value) {
if (__predict_false(value > SSIZE_MAX)) {
__fortify_fatal("%s: %s %zu > SSIZE_MAX", fn, identifier, value);
}
}
static inline void __check_buffer_access(const char* fn, const char* action,
size_t claim, size_t actual) {
if (__predict_false(claim > actual)) {
__fortify_fatal("%s: prevented %zu-byte %s %zu-byte buffer", fn, claim, action, actual);
}
}
char* __strcpy_chk(char* dst, const char* src, size_t dst_len) {
// TODO: optimize so we don't scan src twice.
size_t src_len = __builtin_strlen(src) + 1;
__check_buffer_access("strcpy", "write into", src_len, dst_len);
return __builtin_strcpy(dst, src);
}
size_t __strlcpy_chk(char* dst, const char* src,
size_t supplied_size, size_t dst_len_from_compiler) {
__check_buffer_access("strlcpy", "write into", supplied_size, dst_len_from_compiler);
return __call_bypassing_fortify(strlcpy)(dst, src, supplied_size);
}
char* __strchr_chk(const char* p, int ch, size_t s_len) {
for (;; ++p, s_len--) {
if (__predict_false(s_len == 0)) {
__fortify_fatal("strchr: prevented read past end of buffer");
}
if (*p == static_cast<char>(ch)) {
return const_cast<char*>(p);
}
if (*p == '\0') {
return nullptr;
}
}
}
char* __strcat_chk(char* dst, const char* src, size_t dst_buf_size) {
char* save = dst;
size_t dst_len = __strlen_chk(dst, dst_buf_size);
dst += dst_len;
dst_buf_size -= dst_len;
while ((*dst++ = *src++) != '\0') {
dst_buf_size--;
if (__predict_false(dst_buf_size == 0)) {
__fortify_fatal("strcat: prevented write past end of %zu-byte buffer", dst_buf_size);
}
}
return save;
}
size_t __strlen_chk(const char* s, size_t s_len) {
// TODO: "prevented" here would be a lie because this strlen can run off the end.
// strlen is too important to be expensive, so we wanted to be able to call the optimized
// implementation, but I think we need to implement optimized assembler __strlen_chk routines.
size_t ret = __builtin_strlen(s);
if (__predict_false(ret >= s_len)) {
__fortify_fatal("strlen: detected read past end of buffer");
}
return ret;
}
int __vsprintf_chk(char* dst, int /*flags*/,
size_t dst_len_from_compiler, const char* format, va_list va) {
// The compiler uses SIZE_MAX to mean "no idea", but our vsnprintf rejects sizes that large.
int result = __call_bypassing_fortify(vsnprintf)(dst,
dst_len_from_compiler == SIZE_MAX ? SSIZE_MAX : dst_len_from_compiler,
format, va);
// Try to catch failures after the fact...
__check_buffer_access("vsprintf", "write into", result + 1, dst_len_from_compiler);
return result;
}
mode_t __umask_chk(mode_t mode) {
if (__predict_false((mode & 0777) != mode)) {
__fortify_fatal("umask: called with invalid mask %o", mode);
}
return __umask_real(mode);
}
ssize_t __read_chk(int fd, void* buf, size_t count, size_t buf_size) {
__check_count("read", "count", count);
__check_buffer_access("read", "write into", count, buf_size);
return __call_bypassing_fortify(read)(fd, buf, count);
}
static inline bool needs_mode(int flags) {
return ((flags & O_CREAT) == O_CREAT) || ((flags & O_TMPFILE) == O_TMPFILE);
}
static inline int force_O_LARGEFILE(int flags) {
return flags | O_LARGEFILE;
}
int __open_2(const char* pathname, int flags) {
if (needs_mode(flags)) __fortify_fatal("open: called with O_CREAT/O_TMPFILE but no mode");
return __openat_real(AT_FDCWD, pathname, force_O_LARGEFILE(flags), 0);
}
int __openat_2(int fd, const char* pathname, int flags) {
if (needs_mode(flags)) __fortify_fatal("open: called with O_CREAT/O_TMPFILE but no mode");
return __openat_real(fd, pathname, force_O_LARGEFILE(flags), 0);
}

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@ -165,6 +165,9 @@ int sigemptyset(sigset_t *set) {
memset(set, 0, sizeof(sigset_t)); memset(set, 0, sizeof(sigset_t));
return 0; return 0;
} }
#include "fortify.hpp"
#endif #endif
} // extern "C" } // extern "C"