Subject: Re: [PATCH RESEND] ipv6: return with appropriate error code when sending RH0 using setsockopt()

From: Shan Wei <[email-masked]>
Date: Thu, 04 Sep 2008 13:53:23 +0800

Brian Haley 写道:
> Shan Wei wrote:

...snip...

> There's actually another bug here and in the sendmsg() path in that you
> can set the hdrlen and segments_left fields to be invalid (according to
> RFC3775), as long as the math works out (segments * 2 == length).
> Segments_left should always be 1 and hdrlen 2 for a Type2 routing
> header.  The packet should be dropped at the destination, but we
> probably shouldn't send it.  I can send a patch for that later.
> 
I check the RFC3775. May be the following patch is good to you.

Signed-off-by: Shan Wei <[email-masked]>
---
 net/ipv6/datagram.c      |    8 ++++++--
 net/ipv6/ipv6_sockglue.c |    7 +++++--
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 410046a..cfd499a 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -675,8 +675,12 @@ int datagram_send_ctl(struct net *net,
 				goto exit_f;
 			}
 
-			/* segments left must also match */
-			if ((rthdr->hdrlen >> 1) != rthdr->segments_left) {
+			/* Per RFC3775, for a type 2 routing header,
+			 * the Hdr Ext Len MUST be 2 and the Segments Left
+			 * MUST be 1.
+			 */
+			if ((rthdr->hdrlen != 2) &&
+			    (rthdr->segments_left != 1)) {
 				err = -EINVAL;
 				goto exit_f;
 			}
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 4e5eac3..b967965 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -377,8 +377,11 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 				goto sticky_done;
 			}
 
-			if ((rthdr->hdrlen & 1) ||
-			    (rthdr->hdrlen >> 1) != rthdr->segments_left)
+			/* Per RFC3775, for a type 2 routing header,
+			 * the Hdr Ext Len MUST be 2 and the Segments Left
+			 * MUST be 1.
+			 */
+			if ((rthdr->hdrlen != 2) && (rthdr->segments_left != 1))
 				goto sticky_done;
 		}
 
-- 
1.6.0