* Re: [PATCH] NET: SRv6: seg6_local: Fixed SRH processing when segments left is 0
[not found] <20210131130840.32384-1-suprit.japagal@gmail.com>
@ 2021-01-31 17:33 ` David Ahern
2021-02-02 9:52 ` Ahmed Abdelsalam
0 siblings, 1 reply; 3+ messages in thread
From: David Ahern @ 2021-01-31 17:33 UTC (permalink / raw)
To: Suprit Japagal, davem, yoshfuji, dsahern, David Lebrun; +Cc: netdev
[ cc David Lebrun, author of the original code ]
On 1/31/21 6:08 AM, Suprit Japagal wrote:
> From: "Suprit.Japagal" <suprit.japagal@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.japagal@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);
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] NET: SRv6: seg6_local: Fixed SRH processing when segments left is 0
2021-01-31 17:33 ` [PATCH] NET: SRv6: seg6_local: Fixed SRH processing when segments left is 0 David Ahern
@ 2021-02-02 9:52 ` Ahmed Abdelsalam
[not found] ` <CAGTyo2N5KzFmDgjkqHGZAcO4ZdQ54iKDD6wCYDHemZHFGfP57A@mail.gmail.com>
0 siblings, 1 reply; 3+ messages in thread
From: Ahmed Abdelsalam @ 2021-02-02 9:52 UTC (permalink / raw)
To: David Ahern
Cc: Suprit Japagal, davem, yoshfuji, dsahern, David Lebrun, netdev
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 <dsahern@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.japagal@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.japagal@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.dev@gmail.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] NET: SRv6: seg6_local: Fixed SRH processing when segments left is 0
[not found] ` <CAGTyo2N5KzFmDgjkqHGZAcO4ZdQ54iKDD6wCYDHemZHFGfP57A@mail.gmail.com>
@ 2021-02-03 8:50 ` Ahmed Abdelsalam
0 siblings, 0 replies; 3+ messages in thread
From: Ahmed Abdelsalam @ 2021-02-03 8:50 UTC (permalink / raw)
To: Suprit Japagal
Cc: David Ahern, davem, yoshfuji, dsahern, David Lebrun, netdev
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.japagal@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.dev@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 <dsahern@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.japagal@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.japagal@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.dev@gmail.com>
> >
--
Ahmed Abdelsalam <ahabdels.dev@gmail.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
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[not found] <20210131130840.32384-1-suprit.japagal@gmail.com>
2021-01-31 17:33 ` [PATCH] NET: SRv6: seg6_local: Fixed SRH processing when segments left is 0 David Ahern
2021-02-02 9:52 ` Ahmed Abdelsalam
[not found] ` <CAGTyo2N5KzFmDgjkqHGZAcO4ZdQ54iKDD6wCYDHemZHFGfP57A@mail.gmail.com>
2021-02-03 8:50 ` Ahmed Abdelsalam
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