diff mbox series

[RFC,net-next,v2,3/3] udp6: Use Segment Routing Header for dest address if present

Message ID 20211201202519.3637005-4-andrew@lunn.ch (mailing list archive)
State RFC
Delegated to: Netdev Maintainers
Headers show
Series Fix traceroute in the presence of SRv6 | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers success CCed 5 of 5 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 25 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Andrew Lunn Dec. 1, 2021, 8:25 p.m. UTC
When finding the socket to report an error on, if the invoking packet
is using Segment Routing, the IPv6 destination address is that of an
intermediate router, not the end destination. Extract the ultimate
destination address from the segment address.

This change allows traceroute to function in the presence of Segment
Routing.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---
 net/ipv6/udp.c | 7 +++++++
 1 file changed, 7 insertions(+)

Comments

David Ahern Dec. 2, 2021, 4:40 p.m. UTC | #1
On 12/1/21 1:25 PM, Andrew Lunn wrote:
> @@ -563,12 +564,18 @@ int __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
>  	const struct in6_addr *saddr = &hdr->saddr;
>  	const struct in6_addr *daddr = &hdr->daddr;
>  	struct udphdr *uh = (struct udphdr *)(skb->data+offset);
> +	struct ipv6_sr_hdr *srh;
>  	bool tunnel = false;
>  	struct sock *sk;
>  	int harderr;
>  	int err;
>  	struct net *net = dev_net(skb->dev);
>  
> +	if (opt->flags & IP6SKB_SEG6) {
> +		srh = (struct ipv6_sr_hdr *)(skb->data + opt->srhoff);
> +		daddr = &srh->segments[0];
> +	}
> +
>  	sk = __udp6_lib_lookup(net, daddr, uh->dest, saddr, uh->source,
>  			       inet6_iif(skb), inet6_sdif(skb), udptable, NULL);
>  

similarly for this one, have a helper in seg6.h that returns in6_addr
pointer. It will be referencing within skb->data so should be fine.
diff mbox series

Patch

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 6a0e569f0bb8..6a2288e7ddda 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -40,6 +40,7 @@ 
 #include <net/transp_v6.h>
 #include <net/ip6_route.h>
 #include <net/raw.h>
+#include <net/seg6.h>
 #include <net/tcp_states.h>
 #include <net/ip6_checksum.h>
 #include <net/ip6_tunnel.h>
@@ -563,12 +564,18 @@  int __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	const struct in6_addr *saddr = &hdr->saddr;
 	const struct in6_addr *daddr = &hdr->daddr;
 	struct udphdr *uh = (struct udphdr *)(skb->data+offset);
+	struct ipv6_sr_hdr *srh;
 	bool tunnel = false;
 	struct sock *sk;
 	int harderr;
 	int err;
 	struct net *net = dev_net(skb->dev);
 
+	if (opt->flags & IP6SKB_SEG6) {
+		srh = (struct ipv6_sr_hdr *)(skb->data + opt->srhoff);
+		daddr = &srh->segments[0];
+	}
+
 	sk = __udp6_lib_lookup(net, daddr, uh->dest, saddr, uh->source,
 			       inet6_iif(skb), inet6_sdif(skb), udptable, NULL);