Merge branch 'srv6-traceroute'

Andrew Lunn says:

====================
Fix traceroute in the presence of SRv6

When using SRv6 the destination IP address in the IPv6 header is not
always the true destination, it can be a router along the path that
SRv6 is using.

When ICMP reports an error, e.g, time exceeded, which is what
traceroute uses, it included the packet which invoked the error into
the ICMP message body. Upon receiving such an ICMP packet, the
invoking packet is examined and an attempt is made to find the socket
which sent the packet, so the error can be reported. Lookup is
performed using the source and destination address. If the
intermediary router IP address from the IP header is used, the lookup
fails. It is necessary to dig into the header and find the true
destination address in the Segment Router header, SRH.

v2:
Play games with the skb->network_header rather than clone the skb
v3:
Move helpers into seg6.c
v4:
Move short helper into header file.
Rework getting SRH destination address
v5:
Fix comment to describe function, not caller

Patch 1 exports a helper which can find the SRH in a packet
Patch 2 does the actual examination of the invoking packet
Patch 3 makes use of the results when trying to find the socket.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 31 deletions

diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c
index 2dc40b3f373e..ef88489c71f5 100644
--- a/net/ipv6/seg6_local.c
+++ b/net/ipv6/seg6_local.c
@@ -150,40 +150,11 @@ static struct seg6_local_lwt *seg6_local_lwtunnel(struct lwtunnel_state *lwt)
 	return (struct seg6_local_lwt *)lwt->data;
 }
 
-static struct ipv6_sr_hdr *get_srh(struct sk_buff *skb, int flags)
-{
-	struct ipv6_sr_hdr *srh;
-	int len, srhoff = 0;
-
-	if (ipv6_find_hdr(skb, &srhoff, IPPROTO_ROUTING, NULL, &flags) < 0)
-		return NULL;
-
-	if (!pskb_may_pull(skb, srhoff + sizeof(*srh)))
-		return NULL;
-
-	srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
-
-	len = (srh->hdrlen + 1) << 3;
-
-	if (!pskb_may_pull(skb, srhoff + len))
-		return NULL;
-
-	/* note that pskb_may_pull may change pointers in header;
-	 * for this reason it is necessary to reload them when needed.
-	 */
-	srh = (struct ipv6_sr_hdr *)(skb->data + srhoff);
-
-	if (!seg6_validate_srh(srh, len, true))
-		return NULL;
-
-	return srh;
-}
-
 static struct ipv6_sr_hdr *get_and_validate_srh(struct sk_buff *skb)
 {
 	struct ipv6_sr_hdr *srh;
 
-	srh = get_srh(skb, IP6_FH_F_SKIP_RH);
+	srh = seg6_get_srh(skb, IP6_FH_F_SKIP_RH);
 	if (!srh)
 		return NULL;
 
@@ -200,7 +171,7 @@ static bool decap_and_validate(struct sk_buff *skb, int proto)
 	struct ipv6_sr_hdr *srh;
 	unsigned int off = 0;
 
-	srh = get_srh(skb, 0);
+	srh = seg6_get_srh(skb, 0);
 	if (srh && srh->segments_left > 0)
 		return false;