From 2b432a04a74a6bd338a877bac79f4f5e90d1a57c Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Wed, 9 Mar 2016 21:58:33 -0500 Subject: [PATCH] ax25: add link layer header validation function commit ea47781c26510e5d97f80f9aceafe9065bd5e3aa upstream. As variable length protocol, AX25 fails link layer header validation tests based on a minimum length. header_ops.validate allows protocols to validate headers that are shorter than hard_header_len. Implement this callback for AX25. See also http://comments.gmane.org/gmane.linux.network/401064 Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- net/ax25/ax25_ip.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/net/ax25/ax25_ip.c b/net/ax25/ax25_ip.c index 67de6b33f2c30..5ee8c6fc1a755 100644 --- a/net/ax25/ax25_ip.c +++ b/net/ax25/ax25_ip.c @@ -231,9 +231,24 @@ int ax25_rebuild_header(struct sk_buff *skb) #endif +static bool ax25_validate_header(const char *header, unsigned int len) +{ + ax25_digi digi; + + if (!len) + return false; + + if (header[0]) + return true; + + return ax25_addr_parse(header + 1, len - 1, NULL, NULL, &digi, NULL, + NULL); +} + const struct header_ops ax25_header_ops = { .create = ax25_hard_header, .rebuild = ax25_rebuild_header, + .validate = ax25_validate_header, }; EXPORT_SYMBOL(ax25_hard_header); -- 2.47.3