[OpenWrt-Devel] [PATCH v2] blob: make blob_parse_untrusted more permissive

[Matthias Schiffer]

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

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

v2: added testcase

 blob.c                            |   2 +-
 tests/cram/inputs/signature.ucert | Bin 0 -> 516 bytes
 tests/cram/test_blob_parse.t      |  46 ++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 tests/cram/inputs/signature.ucert

diff --git a/blob.c b/blob.c
index 528e717615d6..433becb904f5 100644
--- a/blob.c
+++ b/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);
diff --git a/tests/cram/inputs/signature.ucert b/tests/cram/inputs/signature.ucert
new file mode 100644
index 0000000000000000000000000000000000000000..4a1da75d0d8daf4054c2aeff6d79ad07b0699535
GIT binary patch
literal 516
zcmbu5J(HSH6o!vQcCywMThd#os3 at 7)LNSVp^5rU0?Cb^Z%7?%exUi(mZu<0T@()s_
z-(r8*qNy^IF4Z~bY2Nd^05t~ye$XgOXqsV%vEwkrQTB;Ry+c&pR>=goWNb9-Bgg5m
zJmz{9vg+Dyvvg5cTVhi>wRLM42qI5f-LXBLQfHVfBGc36LaD7?-?9ic^+IO1Zcxn7
z${A39$F}x*zUj)`fQ;Mffo?hb%Yi8UKr(ux<rt~G+d9+$-o667!Ut;OB!h1N4fuFo
zvy$NIbAZ|lzztmI=;%3*NgQ6_{jbLFKO8?1FTp9wF8txU*nb8H;fheJ@;bwRxJ$8(
zj*LaUqjR?ZTekBVDd{PX4BDKYq?KsS^+A+R4uwy&nB)Cs=5p9`XSo{JFQEWGtNFhj
z^V=OS%vU811+}+mds9VH_eRp%=XY+=mN!X3beA>A5^1KoHU;BR9>(!X7V;UpQR0Nn
W at x)I9QR!%`HdE#z=?{ug)$uzzLZ2Z3

literal 0
HcmV?d00001

diff --git a/tests/cram/test_blob_parse.t b/tests/cram/test_blob_parse.t
index b6cbbaa811b7..5e8b5ff57171 100644
--- a/tests/cram/test_blob_parse.t
+++ b/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
 
-- 
2.26.2


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