Add read()/write() checks

1 files changed, 49 insertions, 0 deletions

diff --git a/include/unistd.h b/include/unistd.h
new file mode 100644
index 0000000..df74dc0
--- /dev/null
+++ b/include/unistd.h
@@ -0,0 +1,49 @@
+/* See LICENSE file for copyright and license details. */
+#ifndef FORTIFY_UNISTD_H_
+#define FORTIFY_UNISTD_H_
+
+#include_next <unistd.h>
+
+#if defined(_FORTIFY_SOURCE) && _FORTIFY_SOURCE > 0 && defined(__OPTIMIZE__) && __OPTIMIZE__ > 0
+
+#define __errordecl(name, msg) extern void name(void) __attribute__((__error__(msg)))
+
+__errordecl(__read_error, "read: buffer overflow detected");
+static inline __attribute__ ((always_inline))
+ssize_t
+__fortify_read(int fd, void *buf, size_t n)
+{
+        size_t bos = __builtin_object_size(buf, 0);
+
+        if (__builtin_constant_p(n) && n > bos)
+                __read_error();
+
+        if (n > bos)
+                __builtin_trap();
+        return read(fd, buf, n);
+}
+
+__errordecl(__write_error, "write: buffer overflow detected");
+static inline __attribute__ ((always_inline))
+ssize_t
+__fortify_write(int fd, void *buf, size_t n)
+{
+        size_t bos = __builtin_object_size(buf, 0);
+
+        if (__builtin_constant_p(n) && n > bos)
+                __write_error();
+
+        if (n > bos)
+                __builtin_trap();
+        return write(fd, buf, n);
+}
+
+#undef read
+#define read(fd, buf, n) __fortify_read(fd, buf, n)
+
+#undef write
+#define write(fd, buf, n) __fortify_write(fd, buf, n)
+
+#endif
+
+#endif