From 65c99de2cb7a569ea17ca35e2f8f1e033421864b Mon Sep 17 00:00:00 2001
From: Nick Kralevich <nnk@google.com>
Date: Wed, 9 Oct 2013 13:44:38 -0700
Subject: [PATCH] FORTIFY_SOURCE: fortify read()

Change-Id: I3d7b4ec86d04efb865117ce7629a2e26917f3331
---
 libc/Android.mk            |  1 +
 libc/bionic/__read_chk.cpp | 43 ++++++++++++++++++++++++++++++++++++++
 libc/include/unistd.h      | 33 +++++++++++++++++++++++++++++
 tests/fortify_test.cpp     | 10 +++++++++
 4 files changed, 87 insertions(+)
 create mode 100644 libc/bionic/__read_chk.cpp

diff --git a/libc/Android.mk b/libc/Android.mk
index f4fdb4c37..b63de889a 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -198,6 +198,7 @@ libc_common_src_files += \
     bionic/__memcpy_chk.cpp \
     bionic/__memmove_chk.cpp \
     bionic/__memset_chk.cpp \
+    bionic/__read_chk.cpp \
     bionic/__recvfrom_chk.cpp \
     bionic/__strcat_chk.cpp \
     bionic/__strchr_chk.cpp \
diff --git a/libc/bionic/__read_chk.cpp b/libc/bionic/__read_chk.cpp
new file mode 100644
index 000000000..d7133f1cd
--- /dev/null
+++ b/libc/bionic/__read_chk.cpp
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2013 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.
+ */
+
+#undef _FORTIFY_SOURCE
+#include <unistd.h>
+#include "libc_logging.h"
+
+extern "C" ssize_t __read_chk(int fd, void* buf, size_t count, size_t buf_size) {
+  if (__predict_false(count > buf_size)) {
+    __fortify_chk_fail("read prevented write past end of buffer", 0);
+  }
+
+  if (__predict_false(count > SSIZE_MAX)) {
+    __fortify_chk_fail("read count > SSIZE_MAX", 0);
+  }
+
+  return read(fd, buf, count);
+}
diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index 60964f0f7..fb1f663da 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -202,6 +202,39 @@ extern int setdomainname(const char *, size_t);
     } while (_rc == -1 && errno == EINTR); \
     _rc; })
 
+#if defined(__BIONIC_FORTIFY)
+extern ssize_t __read_chk(int, void*, size_t, size_t);
+__errordecl(__read_dest_size_error, "read called with size bigger than destination");
+__errordecl(__read_count_toobig_error, "read called with count > SSIZE_MAX");
+extern ssize_t __read_real(int, void*, size_t)
+    __asm__(__USER_LABEL_PREFIX__ "read");
+
+__BIONIC_FORTIFY_INLINE
+ssize_t read(int fd, void* buf, size_t count) {
+    size_t bos = __bos0(buf);
+
+#if !defined(__clang__)
+    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
+        __read_count_toobig_error();
+    }
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __read_real(fd, buf, count);
+    }
+
+    if (__builtin_constant_p(count) && (count > bos)) {
+        __read_dest_size_error();
+    }
+
+    if (__builtin_constant_p(count) && (count <= bos)) {
+        return __read_real(fd, buf, count);
+    }
+#endif
+
+    return __read_chk(fd, buf, count, bos);
+}
+#endif /* defined(__BIONIC_FORTIFY) */
+
 __END_DECLS
 
 #endif /* _UNISTD_H_ */
diff --git a/tests/fortify_test.cpp b/tests/fortify_test.cpp
index d514a3d10..b42c6b781 100644
--- a/tests/fortify_test.cpp
+++ b/tests/fortify_test.cpp
@@ -21,6 +21,7 @@
 #include <sys/stat.h>
 #include <sys/socket.h>
 #include <malloc.h>
+#include <fcntl.h>
 
 // We have to say "DeathTest" here so gtest knows to run this test (which exits)
 // in its own process. Unfortunately, the C preprocessor doesn't give us an
@@ -568,6 +569,15 @@ TEST(DEATHTEST, FD_ZERO_fortified) {
   ASSERT_EXIT(FD_ZERO(set), testing::KilledBySignal(SIGABRT), "");
 }
 
+TEST(DEATHTEST, read_fortified) {
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  char buf[1];
+  size_t ct = atoi("2"); // prevent optimizations
+  int fd = open("/dev/null", O_RDONLY);
+  ASSERT_EXIT(read(fd, buf, ct), testing::KilledBySignal(SIGABRT), "");
+  close(fd);
+}
+
 extern "C" char* __strncat_chk(char*, const char*, size_t, size_t);
 extern "C" char* __strcat_chk(char*, const char*, size_t);