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| author |   doug <doug@openbsd.org> | 2015-04-25 15:28:47 +0000 |
|---|---|---|
| committer | doug <doug@openbsd.org> | 2015-04-25 15:28:47 +0000 |
| commit | d1ca61581d41ca664ca2be81b4cc385710e166f6 (patch) | |
| tree | d58baeb1814e9ead265fcc94377fb812de0ab208 /lib/libssl/bs_cbs.c | |
| parent | allow us to write rules that match directly on the peer AS (diff) | |
| download | wireguard-openbsd-d1ca61581d41ca664ca2be81b4cc385710e166f6.tar.xz wireguard-openbsd-d1ca61581d41ca664ca2be81b4cc385710e166f6.zip | |
Check for invalid leading zeros in CBS_get_asn1_uint64.
ASN.1 integers cannot have all zeros or all ones for the first 9 bits.
This rule ensures the numbers are encoded with the smallest number of
content octets (see ITU-T Rec X.690 section 8.3.2).
Based on BoringSSL commit 5933723b7b592e9914f703d630b596e140c93e16
ok deraadt@ jsing@
Diffstat (limited to 'lib/libssl/bs_cbs.c')
| -rw-r--r-- | lib/libssl/bs_cbs.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/lib/libssl/bs_cbs.c b/lib/libssl/bs_cbs.c index c3d3a8abf2a..d7c0977cf3f 100644 --- a/lib/libssl/bs_cbs.c +++ b/lib/libssl/bs_cbs.c @@ -1,4 +1,4 @@ -/* $OpenBSD: bs_cbs.c,v 1.2 2015/02/06 22:22:33 doug Exp $ */ +/* $OpenBSD: bs_cbs.c,v 1.3 2015/04/25 15:28:47 doug Exp $ */ /* * Copyright (c) 2014, Google Inc. * @@ -317,6 +317,7 @@ CBS_peek_asn1_tag(const CBS *cbs, unsigned tag_value) return CBS_data(cbs)[0] == tag_value; } +/* Encoding details are in ASN.1: X.690 section 8.3 */ int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out) { @@ -332,11 +333,15 @@ CBS_get_asn1_uint64(CBS *cbs, uint64_t *out) len = CBS_len(&bytes); if (len == 0) - /* An INTEGER is encoded with at least one octet. */ + /* An INTEGER is encoded with at least one content octet. */ return 0; if ((data[0] & 0x80) != 0) - /* negative number */ + /* Negative number. */ + return 0; + + if (data[0] == 0 && len > 1 && (data[1] & 0x80) == 0) + /* Violates smallest encoding rule: excessive leading zeros. */ return 0; for (i = 0; i < len; i++) { |