libc: add clang FORTIFY support
This patch adds clang-style FORTIFY to Bionic. For more information on
FORTIFY, please see https://goo.gl/8HS2dW . This implementation works
for versions of clang that don't support diagnose_if, so please see the
"without diagnose_if" sections. We plan to swap to a diagnose_if-based
FORTIFY later this year (since it doesn't really add any features; it
just simplifies the implementation a lot, and it gives us much prettier
diagnostics)
Bug: 32073964
Test: Builds on angler, bullhead, marlin, sailfish. Bionic CTS tests
pass on Angler and Bullhead.
Change-Id: I607aecbeee81529709b1eee7bef5b0836151eb2b
diff --git a/libc/include/fcntl.h b/libc/include/fcntl.h
index 94ea153..88bcc78 100644
--- a/libc/include/fcntl.h
+++ b/libc/include/fcntl.h
@@ -67,9 +67,10 @@
int creat(const char*, mode_t);
int creat64(const char*, mode_t) __INTRODUCED_IN(21);
-int openat(int, const char*, int, ...);
+int openat(int, const char*, int, ...) __overloadable
+ __RENAME_CLANG(openat);
int openat64(int, const char*, int, ...) __INTRODUCED_IN(21);
-int open(const char*, int, ...);
+int open(const char*, int, ...) __overloadable __RENAME_CLANG(open);
int open64(const char*, int, ...) __INTRODUCED_IN(21);
ssize_t splice(int, off64_t*, int, off64_t*, size_t, unsigned int) __INTRODUCED_IN(21);
ssize_t tee(int, int, size_t, unsigned int) __INTRODUCED_IN(21);
@@ -94,15 +95,71 @@
#endif
int __open_2(const char*, int) __INTRODUCED_IN(17);
-int __open_real(const char*, int, ...) __RENAME(open);
int __openat_2(int, const char*, int) __INTRODUCED_IN(17);
+/*
+ * These are the easiest way to call the real open even in clang FORTIFY.
+ */
+int __open_real(const char*, int, ...) __RENAME(open);
int __openat_real(int, const char*, int, ...) __RENAME(openat);
-__errordecl(__creat_missing_mode, "called with O_CREAT, but missing mode");
-__errordecl(__creat_too_many_args, "too many arguments");
+
#if defined(__BIONIC_FORTIFY)
+#define __open_too_many_args_error "too many arguments"
+#define __open_too_few_args_error "called with O_CREAT, but missing mode"
+#if defined(__clang__)
-#if !defined(__clang__)
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+int open(const char* pathname, int flags, mode_t modes, ...) __overloadable
+ __errorattr(__open_too_many_args_error);
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+int open(const char* pathname, int flags) __overloadable
+ __enable_if(flags & O_CREAT, __open_too_few_args_error)
+ __errorattr(__open_too_few_args_error);
+
+/*
+ * pass_object_size serves two purposes here, neither of which involve __bos: it
+ * disqualifies this function from having its address taken (so &open works),
+ * and it makes overload resolution prefer open(const char *, int) over
+ * open(const char *, int, ...).
+ */
+__BIONIC_FORTIFY_INLINE
+int open(const char* const __pass_object_size pathname,
+ int flags) __overloadable {
+ return __open_2(pathname, flags);
+}
+
+__BIONIC_FORTIFY_INLINE
+int open(const char* const __pass_object_size pathname, int flags, mode_t modes)
+ __overloadable {
+ return __open_real(pathname, flags, modes);
+}
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+int openat(int dirfd, const char* pathname, int flags) __overloadable
+ __enable_if(flags & O_CREAT, __open_too_few_args_error)
+ __errorattr(__open_too_few_args_error);
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+int openat(int dirfd, const char* pathname, int flags, mode_t modes, ...)
+ __overloadable
+ __errorattr(__open_too_many_args_error);
+
+__BIONIC_FORTIFY_INLINE
+int openat(int dirfd, const char* const __pass_object_size pathname,
+ int flags) __overloadable {
+ return __openat_2(dirfd, pathname, flags);
+}
+
+__BIONIC_FORTIFY_INLINE
+int openat(int dirfd, const char* const __pass_object_size pathname, int flags,
+ mode_t modes) __overloadable {
+ return __openat_real(dirfd, pathname, flags, modes);
+}
+
+#else /* defined(__clang__) */
+__errordecl(__creat_missing_mode, __open_too_few_args_error);
+__errordecl(__creat_too_many_args, __open_too_many_args_error);
__BIONIC_FORTIFY_INLINE
int open(const char* pathname, int flags, ...) {
@@ -142,8 +199,10 @@
return __openat_real(dirfd, pathname, flags, __builtin_va_arg_pack());
}
-#endif /* !defined(__clang__) */
+#endif /* defined(__clang__) */
+#undef __open_too_many_args_error
+#undef __open_too_few_args_error
#endif /* defined(__BIONIC_FORTIFY) */
__END_DECLS