Working ASLR implementation
Separate files for retouch functionality are in minelf/*
ASLR for shared libraries is controlled by "-a" in ota_from_target_files.
Binary files are self-contained. Retouch logic can recover from crashes.
Signed-off-by: Hristo Bojinov <hristo@google.com>
Change-Id: I76c596abf4febd68c14f9d807ac62e8751e0b1bd
diff --git a/applypatch/applypatch.c b/applypatch/applypatch.c
index d182821..1d9ef6e 100644
--- a/applypatch/applypatch.c
+++ b/applypatch/applypatch.c
@@ -30,16 +30,21 @@
#include "mtdutils/mtdutils.h"
#include "edify/expr.h"
-static int SaveFileContents(const char* filename, FileContents file);
+int SaveFileContents(const char* filename, FileContents file);
static int LoadPartitionContents(const char* filename, FileContents* file);
int ParseSha1(const char* str, uint8_t* digest);
static ssize_t FileSink(unsigned char* data, ssize_t len, void* token);
static int mtd_partitions_scanned = 0;
-// Read a file into memory; store it and its associated metadata in
-// *file. Return 0 on success.
-int LoadFileContents(const char* filename, FileContents* file) {
+// Read a file into memory; optionally (retouch_flag == RETOUCH_DO_MASK) mask
+// the retouched entries back to their original value (such that SHA-1 checks
+// don't fail due to randomization); store the file contents and associated
+// metadata in *file.
+//
+// Return 0 on success.
+int LoadFileContents(const char* filename, FileContents* file,
+ int retouch_flag) {
file->data = NULL;
// A special 'filename' beginning with "MTD:" or "EMMC:" means to
@@ -75,6 +80,20 @@
}
fclose(f);
+ // apply_patch[_check] functions are blind to randomization. Randomization
+ // is taken care of in [Undo]RetouchBinariesFn. If there is a mismatch
+ // within a file, this means the file is assumed "corrupt" for simplicity.
+ if (retouch_flag) {
+ int32_t desired_offset = 0;
+ if (retouch_mask_data(file->data, file->size,
+ &desired_offset, NULL) != RETOUCH_DATA_MATCHED) {
+ printf("error trying to mask retouch entries\n");
+ free(file->data);
+ file->data = NULL;
+ return -1;
+ }
+ }
+
SHA(file->data, file->size, file->sha1);
return 0;
}
@@ -303,7 +322,7 @@
// Save the contents of the given FileContents object under the given
// filename. Return 0 on success.
-static int SaveFileContents(const char* filename, FileContents file) {
+int SaveFileContents(const char* filename, FileContents file) {
int fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC);
if (fd < 0) {
printf("failed to open \"%s\" for write: %s\n",
@@ -477,7 +496,7 @@
// LoadFileContents is successful. (Useful for reading
// partitions, where the filename encodes the sha1s; no need to
// check them twice.)
- if (LoadFileContents(filename, &file) != 0 ||
+ if (LoadFileContents(filename, &file, RETOUCH_DO_MASK) != 0 ||
(num_patches > 0 &&
FindMatchingPatch(file.sha1, patch_sha1_str, num_patches) < 0)) {
printf("file \"%s\" doesn't have any of expected "
@@ -491,7 +510,7 @@
// exists and matches the sha1 we're looking for, the check still
// passes.
- if (LoadFileContents(CACHE_TEMP_SOURCE, &file) != 0) {
+ if (LoadFileContents(CACHE_TEMP_SOURCE, &file, RETOUCH_DO_MASK) != 0) {
printf("failed to load cache file\n");
return 1;
}
@@ -617,7 +636,8 @@
int made_copy = 0;
// We try to load the target file into the source_file object.
- if (LoadFileContents(target_filename, &source_file) == 0) {
+ if (LoadFileContents(target_filename, &source_file,
+ RETOUCH_DO_MASK) == 0) {
if (memcmp(source_file.sha1, target_sha1, SHA_DIGEST_SIZE) == 0) {
// The early-exit case: the patch was already applied, this file
// has the desired hash, nothing for us to do.
@@ -633,7 +653,8 @@
// Need to load the source file: either we failed to load the
// target file, or we did but it's different from the source file.
free(source_file.data);
- LoadFileContents(source_filename, &source_file);
+ LoadFileContents(source_filename, &source_file,
+ RETOUCH_DO_MASK);
}
if (source_file.data != NULL) {
@@ -648,7 +669,8 @@
free(source_file.data);
printf("source file is bad; trying copy\n");
- if (LoadFileContents(CACHE_TEMP_SOURCE, ©_file) < 0) {
+ if (LoadFileContents(CACHE_TEMP_SOURCE, ©_file,
+ RETOUCH_DO_MASK) < 0) {
// fail.
printf("failed to read copy file\n");
return 1;