ASN.1: Handle 'ANY OPTIONAL' in grammar
An ANY object in an ASN.1 grammar that is marked OPTIONAL should be skipped
if there is no more data to be had.
This can be tested by editing X.509 certificates or PKCS#7 messages to
remove the NULL from subobjects that look like the following:
SEQUENCE {
OBJECT(2a864886f70d01010b);
NULL();
}
This is an algorithm identifier plus an optional parameter.
The modified DER can be passed to one of:
keyctl padd asymmetric "" @s </tmp/modified.x509
keyctl padd pkcs7_test foo @s </tmp/modified.pkcs7
It should work okay with the patch and produce EBADMSG without.
Signed-off-by: David Howells <[email protected]>
Tested-by: Marcel Holtmann <[email protected]>
Reviewed-by: David Woodhouse <[email protected]>
diff --git a/lib/asn1_decoder.c b/lib/asn1_decoder.c
index 3f74dd3..2b3f46c 100644
--- a/lib/asn1_decoder.c
+++ b/lib/asn1_decoder.c
@@ -24,12 +24,16 @@
[ASN1_OP_MATCH_JUMP] = 1 + 1 + 1,
[ASN1_OP_MATCH_JUMP_OR_SKIP] = 1 + 1 + 1,
[ASN1_OP_MATCH_ANY] = 1,
+ [ASN1_OP_MATCH_ANY_OR_SKIP] = 1,
[ASN1_OP_MATCH_ANY_ACT] = 1 + 1,
+ [ASN1_OP_MATCH_ANY_ACT_OR_SKIP] = 1 + 1,
[ASN1_OP_COND_MATCH_OR_SKIP] = 1 + 1,
[ASN1_OP_COND_MATCH_ACT_OR_SKIP] = 1 + 1 + 1,
[ASN1_OP_COND_MATCH_JUMP_OR_SKIP] = 1 + 1 + 1,
[ASN1_OP_COND_MATCH_ANY] = 1,
+ [ASN1_OP_COND_MATCH_ANY_OR_SKIP] = 1,
[ASN1_OP_COND_MATCH_ANY_ACT] = 1 + 1,
+ [ASN1_OP_COND_MATCH_ANY_ACT_OR_SKIP] = 1 + 1,
[ASN1_OP_COND_FAIL] = 1,
[ASN1_OP_COMPLETE] = 1,
[ASN1_OP_ACT] = 1 + 1,
@@ -304,7 +308,9 @@
/* Decide how to handle the operation */
switch (op) {
case ASN1_OP_MATCH_ANY_ACT:
+ case ASN1_OP_MATCH_ANY_ACT_OR_SKIP:
case ASN1_OP_COND_MATCH_ANY_ACT:
+ case ASN1_OP_COND_MATCH_ANY_ACT_OR_SKIP:
ret = actions[machine[pc + 1]](context, hdr, tag, data + dp, len);
if (ret < 0)
return ret;
@@ -321,8 +327,10 @@
case ASN1_OP_MATCH:
case ASN1_OP_MATCH_OR_SKIP:
case ASN1_OP_MATCH_ANY:
+ case ASN1_OP_MATCH_ANY_OR_SKIP:
case ASN1_OP_COND_MATCH_OR_SKIP:
case ASN1_OP_COND_MATCH_ANY:
+ case ASN1_OP_COND_MATCH_ANY_OR_SKIP:
skip_data:
if (!(flags & FLAG_CONS)) {
if (flags & FLAG_INDEFINITE_LENGTH) {
