| Message ID | 20211208173831.3791157-4-andrew@lunn.ch (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Fix traceroute in the presence of SRv6 | expand |
On Wed, Dec 8, 2021 at 12:38 PM Andrew Lunn <andrew@lunn.ch> wrote: > > 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> > --- > include/net/seg6.h | 19 +++++++++++++++++++ > net/ipv6/udp.c | 3 ++- > 2 files changed, 21 insertions(+), 1 deletion(-) > > diff --git a/include/net/seg6.h b/include/net/seg6.h > index 02b0cd305787..af668f17b398 100644 > --- a/include/net/seg6.h > +++ b/include/net/seg6.h > @@ -65,4 +65,23 @@ extern int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, > extern int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh); > extern int seg6_lookup_nexthop(struct sk_buff *skb, struct in6_addr *nhaddr, > u32 tbl_id); > + > +/* If the packet which invoked an ICMP error contains an SRH return > + * the true destination address from within the SRH, otherwise use the > + * destination address in the IP header. > + */ nit: the above describes the behavior of the caller, not the function. The function returns NULL if no SRH is found. > +static inline const struct in6_addr *seg6_get_daddr(struct sk_buff *skb, > + struct inet6_skb_parm *opt) > +{ > + struct ipv6_sr_hdr *srh; > + > + if (opt->flags & IP6SKB_SEG6) { > + srh = (struct ipv6_sr_hdr *)(skb->data + opt->srhoff); > + return &srh->segments[0]; > + } > + > + return NULL; > +} > + > + > #endif > diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c > index 6a0e569f0bb8..a14375e3f923 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> > @@ -561,7 +562,7 @@ int __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt, > struct ipv6_pinfo *np; > const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data; > const struct in6_addr *saddr = &hdr->saddr; > - const struct in6_addr *daddr = &hdr->daddr; > + const struct in6_addr *daddr = seg6_get_daddr(skb, opt) ? : &hdr->daddr; > struct udphdr *uh = (struct udphdr *)(skb->data+offset); > bool tunnel = false; > struct sock *sk; > -- > 2.33.1 >
> > +/* If the packet which invoked an ICMP error contains an SRH return > > + * the true destination address from within the SRH, otherwise use the > > + * destination address in the IP header. > > + */ > > nit: the above describes the behavior of the caller, not the function. > The function returns NULL if no SRH is found. Yes, i will fix that. Thanks Andrew
diff --git a/include/net/seg6.h b/include/net/seg6.h index 02b0cd305787..af668f17b398 100644 --- a/include/net/seg6.h +++ b/include/net/seg6.h @@ -65,4 +65,23 @@ extern int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, extern int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh); extern int seg6_lookup_nexthop(struct sk_buff *skb, struct in6_addr *nhaddr, u32 tbl_id); + +/* If the packet which invoked an ICMP error contains an SRH return + * the true destination address from within the SRH, otherwise use the + * destination address in the IP header. + */ +static inline const struct in6_addr *seg6_get_daddr(struct sk_buff *skb, + struct inet6_skb_parm *opt) +{ + struct ipv6_sr_hdr *srh; + + if (opt->flags & IP6SKB_SEG6) { + srh = (struct ipv6_sr_hdr *)(skb->data + opt->srhoff); + return &srh->segments[0]; + } + + return NULL; +} + + #endif diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 6a0e569f0bb8..a14375e3f923 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> @@ -561,7 +562,7 @@ int __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt, struct ipv6_pinfo *np; const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data; const struct in6_addr *saddr = &hdr->saddr; - const struct in6_addr *daddr = &hdr->daddr; + const struct in6_addr *daddr = seg6_get_daddr(skb, opt) ? : &hdr->daddr; struct udphdr *uh = (struct udphdr *)(skb->data+offset); bool tunnel = false; struct sock *sk;
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> --- include/net/seg6.h | 19 +++++++++++++++++++ net/ipv6/udp.c | 3 ++- 2 files changed, 21 insertions(+), 1 deletion(-)