Hi Suprit, As you see the in the pseudocode, if Segments Left = 0, the End function will stop processing the SRH and will process upper layer protocols for OAM (e.g., ICMP).
The packet will not be forwarded further. What you propose here is a different thing, you want to decap the SRv6 headers and forward the packet further if Segments Left = 0. This is not a correct symantic of SRv6 End Behavior. But if you need such behavior in your network, it already defined by another flavor of the End function called Ultimate Segment Decapsulation (USD) [2] Please feel free to submit a patch to support this USD flavor of END. [2] https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-28#section-4.16.3 Thanks Ahmed On Tue, 2 Feb 2021 16:50:58 +0530 Suprit Japagal <suprit.japa...@gmail.com> wrote: > Hi, > > As per the section 4.1 of [1]: > > "When N receives a packet whose IPv6 DA is S and S is a local *End SID*, > > N does: > > S01. When an SRH is processed { > S02. If (Segments Left == 0) { > S03. Stop processing the SRH, and proceed to process the next > header in the packet, whose type is identified by > the Next Header field in the routing header. > > S04. } > " > S is the DA which is a local End SID and when SRH is processed, the > segments left field can be 0 as mentioned above. > Same goes for End.X SID and End.T SID as per section 4.2 and 4.3 of [1] > respectively. > > Packets processed by End, End.X and End.T behaviors can have a Segment Left > Value > of zero. > > [1]https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-28 > > Thanks, > Suprit J > > On Tue, Feb 2, 2021 at 3:22 PM Ahmed Abdelsalam <ahabdels....@gmail.com> > wrote: > > > The current implementation is correct. This patch is introducing incorrect > > symantic to SRv6 End and End.T behaviors. > > > > SRv6 End and End.T behaviors (among other behaviors) are defined in the > > SRv6 Network Programming draft (Soon to published as an RFC) [1]. > > > > SRv6 End and End.T behaviors are used to implement Traffic Engineering (TE) > > use-cases, where a node recieves the packet and send it to the next SID > > from > > the SRH SIDList. > > > > Packets processed by End and End.T behaviors can not have a Segment Left > > Value > > of zero. > > > > Please refer to sections 4.1 and 4.3 of [1]. > > > > > > [1] > > https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming-28 > > > > Ahmed > > > > > > On Sun, 31 Jan 2021 10:33:14 -0700 > > David Ahern <dsah...@gmail.com> wrote: > > > > > [ cc David Lebrun, author of the original code ] > > > > > > On 1/31/21 6:08 AM, Suprit Japagal wrote: > > > > From: "Suprit.Japagal" <suprit.japa...@gmail.com> > > > > > > > > According to the standard IETF RFC 8754, section 4.3.1.1 > > > > (https://tools.ietf.org/html/rfc8754#section-4.3.1.1) > > > > When the segments left in SRH equals to 0, proceed to process the > > > > next header in the packet, whose type is identified by the > > > > Next header field of the routing header. > > > > > > > > Signed-off-by: Suprit.Japagal <suprit.japa...@gmail.com> > > > > --- > > > > net/ipv6/seg6_local.c | 54 > > +++++++++++++++++++++++++++++++++++++++++++++------ > > > > 1 file changed, 48 insertions(+), 6 deletions(-) > > > > > > > > diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c > > > > index b07f7c1..b17f9dc 100644 > > > > --- a/net/ipv6/seg6_local.c > > > > +++ b/net/ipv6/seg6_local.c > > > > @@ -273,11 +273,25 @@ static int input_action_end(struct sk_buff *skb, > > struct seg6_local_lwt *slwt) > > > > { > > > > struct ipv6_sr_hdr *srh; > > > > > > > > - srh = get_and_validate_srh(skb); > > > > + srh = get_srh(skb); > > > > if (!srh) > > > > goto drop; > > > > > > > > - advance_nextseg(srh, &ipv6_hdr(skb)->daddr); > > > > +#ifdef CONFIG_IPV6_SEG6_HMAC > > > > + if (srh->segments_left > 0) > > > > + if (!seg6_hmac_validate_skb(skb)) > > > > + goto drop; > > > > +#endif > > > > + > > > > + if (srh->segments_left == 0) { > > > > + if (!decap_and_validate(skb, srh->nexthdr)) > > > > + goto drop; > > > > + > > > > + if (!pskb_may_pull(skb, sizeof(struct ipv6hdr))) > > > > + goto drop; > > > > + } else { > > > > + advance_nextseg(srh, &ipv6_hdr(skb)->daddr); > > > > + } > > > > > > > > seg6_lookup_nexthop(skb, NULL, 0); > > > > > > > > @@ -293,11 +307,25 @@ static int input_action_end_x(struct sk_buff > > *skb, struct seg6_local_lwt *slwt) > > > > { > > > > struct ipv6_sr_hdr *srh; > > > > > > > > - srh = get_and_validate_srh(skb); > > > > + srh = get_srh(skb); > > > > if (!srh) > > > > goto drop; > > > > > > > > - advance_nextseg(srh, &ipv6_hdr(skb)->daddr); > > > > +#ifdef CONFIG_IPV6_SEG6_HMAC > > > > + if (srh->segments_left > 0) > > > > + if (!seg6_hmac_validate_skb(skb)) > > > > + goto drop; > > > > +#endif > > > > + > > > > + if (srh->segments_left == 0) { > > > > + if (!decap_and_validate(skb, srh->nexthdr)) > > > > + goto drop; > > > > + > > > > + if (!pskb_may_pull(skb, sizeof(struct ipv6hdr))) > > > > + goto drop; > > > > + } else { > > > > + advance_nextseg(srh, &ipv6_hdr(skb)->daddr); > > > > + } > > > > > > > > seg6_lookup_nexthop(skb, &slwt->nh6, 0); > > > > > > > > @@ -312,11 +340,25 @@ static int input_action_end_t(struct sk_buff > > *skb, struct seg6_local_lwt *slwt) > > > > { > > > > struct ipv6_sr_hdr *srh; > > > > > > > > - srh = get_and_validate_srh(skb); > > > > + srh = get_srh(skb); > > > > if (!srh) > > > > goto drop; > > > > > > > > - advance_nextseg(srh, &ipv6_hdr(skb)->daddr); > > > > +#ifdef CONFIG_IPV6_SEG6_HMAC > > > > + if (srh->segments_left > 0) > > > > + if (!seg6_hmac_validate_skb(skb)) > > > > + goto drop; > > > > +#endif > > > > + > > > > + if (srh->segments_left == 0) { > > > > + if (!decap_and_validate(skb, srh->nexthdr)) > > > > + goto drop; > > > > + > > > > + if (!pskb_may_pull(skb, sizeof(struct ipv6hdr))) > > > > + goto drop; > > > > + } else { > > > > + advance_nextseg(srh, &ipv6_hdr(skb)->daddr); > > > > + } > > > > > > > > seg6_lookup_nexthop(skb, NULL, slwt->table); > > > > > > > > > > > > > > > > > -- > > Ahmed Abdelsalam <ahabdels....@gmail.com> > > -- Ahmed Abdelsalam <ahabdels....@gmail.com>
