blob: make blob_parse_untrusted more permissive

Some tools like ucert use concatenations of multiple blobs. Account for
this case by allowing the underlying buffer length to be greater than
the blob length.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>

blob.c

@@ -277,7 +277,7 @@ blob_parse_untrusted(struct blob_attr *attr, size_t attr_len, struct blob_attr *
 		return 0;
 
 	len = blob_raw_len(attr);
-	if (len != attr_len)
+	if (attr_len < len)
 		return 0;
 
 	memset(data, 0, sizeof(struct blob_attr *) * max);

tests/cram/test_blob_parse.t

@@ -21,6 +21,29 @@ check that blob_parse is producing expected results:
   }
   ---
 
+  $ valgrind --quiet --leak-check=full test-blob-parse $TEST_INPUTS/signature.ucert
+  === CHAIN ELEMENT 01 ===
+  signature:
+  ---
+  untrusted comment: signed by key ca85add129e64bab
+  RWTKha3RKeZLq0Sb8kCH9p/3BcFFud8rJnZiRICyRNhjbbpeZSwO2VhkwGaMd7ujW2/YSvT3O67pB0QguV6czgpP5kLX4AKBaQ4=
+  ---
+  payload:
+  ---
+  "ucert": {
+  \t"certtype": 1, (esc)
+  \t"validfrom": 1588532405, (esc)
+  \t"expiresat": 1620068405, (esc)
+  \t"pubkey": "untrusted comment: Local build key\\nRWTKha3RKeZLq1EaPsqvnXu+FqLMHZIS7nvDgwjpRo69j+th6eihGvQo\\n" (esc)
+  }
+  ---
+  === CHAIN ELEMENT 02 ===
+  signature:
+  ---
+  untrusted comment: signed by key ca85add129e64bab
+  RWTKha3RKeZLq9VW9CIMyumCQ4J0iFPLQYXr/YvUhw0OTrwpSh2XpKaRZQNZCXfO8ooMOCvG2TPor2veDjskHP1R2RGPIHp57wA=
+  ---
+
   $ valgrind --quiet --leak-check=full test-blob-parse $TEST_INPUTS/invalid.ucert
   cannot parse cert invalid.ucert
 
@@ -41,6 +64,29 @@ check that blob_parse is producing expected results:
   }
   ---
 
+  $ test-blob-parse-san $TEST_INPUTS/signature.ucert
+  === CHAIN ELEMENT 01 ===
+  signature:
+  ---
+  untrusted comment: signed by key ca85add129e64bab
+  RWTKha3RKeZLq0Sb8kCH9p/3BcFFud8rJnZiRICyRNhjbbpeZSwO2VhkwGaMd7ujW2/YSvT3O67pB0QguV6czgpP5kLX4AKBaQ4=
+  ---
+  payload:
+  ---
+  "ucert": {
+  \t"certtype": 1, (esc)
+  \t"validfrom": 1588532405, (esc)
+  \t"expiresat": 1620068405, (esc)
+  \t"pubkey": "untrusted comment: Local build key\\nRWTKha3RKeZLq1EaPsqvnXu+FqLMHZIS7nvDgwjpRo69j+th6eihGvQo\\n" (esc)
+  }
+  ---
+  === CHAIN ELEMENT 02 ===
+  signature:
+  ---
+  untrusted comment: signed by key ca85add129e64bab
+  RWTKha3RKeZLq9VW9CIMyumCQ4J0iFPLQYXr/YvUhw0OTrwpSh2XpKaRZQNZCXfO8ooMOCvG2TPor2veDjskHP1R2RGPIHp57wA=
+  ---
+
   $ test-blob-parse-san $TEST_INPUTS/invalid.ucert
   cannot parse cert invalid.ucert