Define and use read_u{8,16,64}
A large portion of the utility functions is parsing the data structures
on disk. The pattern always involve: reading a certain size of data,
ensuring that there is enough space available; converting the value from
big-endian to host byte order and advancing the pointer pass that value.
Define new functions to capture this task. Use these functions for
parsing the TrillanLogRoot descriptor.
Test: m libavb_host_unittest && ./out/host/linux-x86/nativetest64/libavb_host_unittest/libavb_host_unittest
Test: m libavb_host_unittest && ./out/host/linux-x86/nativetest/libavb_host_unittest/libavb_host_unittest
Bug: 154303414
Change-Id: Ie23639f69804dc6a23c66a5e96c45d8c0ca7586c
diff --git a/libavb_aftl/avb_aftl_util.c b/libavb_aftl/avb_aftl_util.c
index 98387d1..29c2ef5 100644
--- a/libavb_aftl/avb_aftl_util.c
+++ b/libavb_aftl/avb_aftl_util.c
@@ -393,6 +393,35 @@
return retval;
}
+/* Defines helper functions read_u8, read_u16 and read_u64. These functions can
+ * be used to read from a |data| stream a |value| of a specific size. The value
+ * endianness is converted from big-endian to host. We ensure that the read do
+ * not overflow beyond |data_end|. If successful, |data| is brought forward by
+ * the size of the value read.
+ */
+#define _read_u(fct) \
+ { \
+ size_t value_size = sizeof(*value); \
+ if ((*data + value_size) < *data) return false; \
+ if ((*data + value_size) > data_end) return false; \
+ avb_memcpy(value, *data, value_size); \
+ *value = fct(*value); \
+ *data += value_size; \
+ return true; \
+ }
+static bool read_u8(uint8_t* value, uint8_t** data, uint8_t* data_end) {
+ _read_u();
+}
+AVB_ATTR_WARN_UNUSED_RESULT
+static bool read_u16(uint16_t* value, uint8_t** data, uint8_t* data_end) {
+ _read_u(avb_be16toh);
+}
+AVB_ATTR_WARN_UNUSED_RESULT
+static bool read_u64(uint64_t* value, uint8_t** data, uint8_t* data_end) {
+ _read_u(avb_be64toh);
+}
+AVB_ATTR_WARN_UNUSED_RESULT
+
/* Allocates and populates a TrillianLogRootDescriptor element in an
AftlIcpEntry from a binary blob.
The blob is expected to be pointing to the beginning of a
@@ -403,96 +432,83 @@
static bool parse_trillian_log_root_descriptor(AftlIcpEntry* icp_entry,
uint8_t** aftl_blob,
size_t aftl_blob_remaining) {
- size_t parsed_size;
-
avb_assert(icp_entry);
avb_assert(aftl_blob);
avb_assert(aftl_blob_remaining >= AVB_AFTL_MIN_TLRD_SIZE);
+ uint8_t* blob_end = *aftl_blob + aftl_blob_remaining;
+
/* Copy in the version field from the blob. */
- avb_memcpy(&(icp_entry->log_root_descriptor.version),
- *aftl_blob,
- avb_aftl_member_size(TrillianLogRootDescriptor, version));
- icp_entry->log_root_descriptor.version =
- avb_be16toh(icp_entry->log_root_descriptor.version);
- *aftl_blob += avb_aftl_member_size(TrillianLogRootDescriptor, version);
- parsed_size = avb_aftl_member_size(TrillianLogRootDescriptor, version);
- /* Copy in the tree size field from the blob. */
- avb_memcpy(&(icp_entry->log_root_descriptor.tree_size),
- *aftl_blob,
- avb_aftl_member_size(TrillianLogRootDescriptor, tree_size));
- icp_entry->log_root_descriptor.tree_size =
- avb_be64toh(icp_entry->log_root_descriptor.tree_size);
- *aftl_blob += avb_aftl_member_size(TrillianLogRootDescriptor, tree_size);
- parsed_size += avb_aftl_member_size(TrillianLogRootDescriptor, tree_size);
- /* Copy in the root hash size field from the blob. */
- avb_memcpy(&(icp_entry->log_root_descriptor.root_hash_size),
- *aftl_blob,
- avb_aftl_member_size(TrillianLogRootDescriptor, root_hash_size));
- if (icp_entry->log_root_descriptor.root_hash_size != AVB_AFTL_HASH_SIZE) {
- avb_error("Invalid root hash size.\n");
- free_aftl_icp_entry(icp_entry);
+ if (!read_u16(
+ &(icp_entry->log_root_descriptor.version), aftl_blob, blob_end)) {
+ avb_error("Unable to parse version.\n");
return false;
}
- *aftl_blob += avb_aftl_member_size(TrillianLogRootDescriptor, root_hash_size);
- parsed_size +=
- avb_aftl_member_size(TrillianLogRootDescriptor, root_hash_size);
+
+ /* Copy in the tree size field from the blob. */
+ if (!read_u64(
+ &(icp_entry->log_root_descriptor.tree_size), aftl_blob, blob_end)) {
+ avb_error("Unable to parse tree size.\n");
+ return false;
+ }
+
+ /* Copy in the root hash size field from the blob. */
+ if (!read_u8(&(icp_entry->log_root_descriptor.root_hash_size),
+ aftl_blob,
+ blob_end)) {
+ avb_error("Unable to parse root hash size.\n");
+ return false;
+ }
+ if (icp_entry->log_root_descriptor.root_hash_size != AVB_AFTL_HASH_SIZE) {
+ avb_error("Invalid root hash size.\n");
+ return false;
+ }
+
/* Copy in the root hash from the blob. */
icp_entry->log_root_descriptor.root_hash =
(uint8_t*)avb_calloc(icp_entry->log_root_descriptor.root_hash_size);
if (!icp_entry->log_root_descriptor.root_hash) {
avb_error("Failure to allocate root hash.\n");
- free_aftl_icp_entry(icp_entry);
return false;
}
-
avb_memcpy(icp_entry->log_root_descriptor.root_hash,
*aftl_blob,
icp_entry->log_root_descriptor.root_hash_size);
*aftl_blob += icp_entry->log_root_descriptor.root_hash_size;
- parsed_size += icp_entry->log_root_descriptor.root_hash_size;
+
/* Copy in the timestamp field from the blob. */
- avb_memcpy(&(icp_entry->log_root_descriptor.timestamp),
- *aftl_blob,
- avb_aftl_member_size(TrillianLogRootDescriptor, timestamp));
- icp_entry->log_root_descriptor.timestamp =
- avb_be64toh(icp_entry->log_root_descriptor.timestamp);
- *aftl_blob += avb_aftl_member_size(TrillianLogRootDescriptor, timestamp);
- parsed_size += avb_aftl_member_size(TrillianLogRootDescriptor, timestamp);
+ if (!read_u64(
+ &(icp_entry->log_root_descriptor.timestamp), aftl_blob, blob_end)) {
+ avb_error("Unable to parse timestamp.\n");
+ return false;
+ }
+
/* Copy in the revision field from the blob. */
- avb_memcpy(&(icp_entry->log_root_descriptor.revision),
- *aftl_blob,
- avb_aftl_member_size(TrillianLogRootDescriptor, revision));
- icp_entry->log_root_descriptor.revision =
- avb_be64toh(icp_entry->log_root_descriptor.revision);
- *aftl_blob += avb_aftl_member_size(TrillianLogRootDescriptor, revision);
- parsed_size += avb_aftl_member_size(TrillianLogRootDescriptor, revision);
+ if (!read_u64(
+ &(icp_entry->log_root_descriptor.revision), aftl_blob, blob_end)) {
+ avb_error("Unable to parse revision.\n");
+ return false;
+ }
+
/* Copy in the metadata size field from the blob. */
- avb_memcpy(&(icp_entry->log_root_descriptor.metadata_size),
- *aftl_blob,
- avb_aftl_member_size(TrillianLogRootDescriptor, metadata_size));
- icp_entry->log_root_descriptor.metadata_size =
- avb_be16toh(icp_entry->log_root_descriptor.metadata_size);
- *aftl_blob += avb_aftl_member_size(TrillianLogRootDescriptor, metadata_size);
- parsed_size += avb_aftl_member_size(TrillianLogRootDescriptor, metadata_size);
+ if (!read_u16(&(icp_entry->log_root_descriptor.metadata_size),
+ aftl_blob,
+ blob_end)) {
+ avb_error("Unable to parse metadata size.\n");
+ return false;
+ }
+
if (icp_entry->log_root_descriptor.metadata_size >
AVB_AFTL_MAX_METADATA_SIZE) {
avb_error("Invalid metadata size.\n");
- free_aftl_icp_entry(icp_entry);
return false;
}
- if (icp_entry->log_root_descriptor.metadata_size + parsed_size >
- aftl_blob_remaining) {
- avb_error("Invalid AftlImage.\n");
- free_aftl_icp_entry(icp_entry);
- return false;
- }
+
/* If it exists, copy in the metadata field from the blob. */
if (icp_entry->log_root_descriptor.metadata_size > 0) {
icp_entry->log_root_descriptor.metadata =
(uint8_t*)avb_calloc(icp_entry->log_root_descriptor.metadata_size);
if (!icp_entry->log_root_descriptor.metadata) {
avb_error("Failure to allocate metadata.\n");
- free_aftl_icp_entry(icp_entry);
return false;
}
avb_memcpy(icp_entry->log_root_descriptor.metadata,
@@ -748,6 +764,7 @@
}
if (!parse_trillian_log_root_descriptor(
icp_entry, aftl_blob, icp_entry->log_root_descriptor_size)) {
+ free_aftl_icp_entry(icp_entry);
return NULL;
}
