On Sat, Aug 12, 2023 at 08:09:25PM +0200, Andrea Mayer wrote: > The NEXT-C-SID mechanism described in [1] offers the possibility of > encoding several SRv6 segments within a single 128 bit SID address. Such > a SID address is called a Compressed SID (C-SID) container. In this way, > the length of the SID List can be drastically reduced. > > A SID instantiated with the NEXT-C-SID flavor considers an IPv6 address > logically structured in three main blocks: i) Locator-Block; ii) > Locator-Node Function; iii) Argument. > > C-SID container > +------------------------------------------------------------------+ > | Locator-Block |Loc-Node| Argument | > | |Function| | > +------------------------------------------------------------------+ > <--------- B -----------> <- NF -> <------------- A ---------------> > > (i) The Locator-Block can be any IPv6 prefix available to the provider; > > (ii) The Locator-Node Function represents the node and the function to > be triggered when a packet is received on the node; > > (iii) The Argument carries the remaining C-SIDs in the current C-SID > container. > > This patch leverages the NEXT-C-SID mechanism previously introduced in the > Linux SRv6 subsystem [2] to support SID compression capabilities in the > SRv6 End.X behavior [3]. > An SRv6 End.X behavior with NEXT-C-SID flavor works as an End.X behavior > but it is capable of processing the compressed SID List encoded in C-SID > containers. > > An SRv6 End.X behavior with NEXT-C-SID flavor can be configured to support > user-provided Locator-Block and Locator-Node Function lengths. In this > implementation, such lengths must be evenly divisible by 8 (i.e. must be > byte-aligned), otherwise the kernel informs the user about invalid > values with a meaningful error code and message through netlink_ext_ack. > > If Locator-Block and/or Locator-Node Function lengths are not provided > by the user during configuration of an SRv6 End.X behavior instance with > NEXT-C-SID flavor, the kernel will choose their default values i.e., > 32-bit Locator-Block and 16-bit Locator-Node Function. > > [1] - https://datatracker.ietf.org/doc/html/draft-ietf-spring-srv6-srh-compression > [2] - https://lore.kernel.org/all/20220912171619.16943-1-andrea.mayer@xxxxxxxxxxx/ > [3] - https://datatracker.ietf.org/doc/html/rfc8986#name-endx-l3-cross-connect > > Signed-off-by: Andrea Mayer <andrea.mayer@xxxxxxxxxxx> > --- > net/ipv6/seg6_local.c | 108 ++++++++++++++++++++++++++++++++++-------- > 1 file changed, 88 insertions(+), 20 deletions(-) > > diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c > index dd433cc265c8..24e2b4b494cb 100644 > --- a/net/ipv6/seg6_local.c > +++ b/net/ipv6/seg6_local.c > @@ -109,15 +109,19 @@ struct bpf_lwt_prog { > #define next_csid_chk_lcnode_fn_bits(flen) \ > next_csid_chk_lcblock_bits(flen) > > +/* flag indicating that flavors are set up for a given End* behavior */ > +#define SEG6_F_LOCAL_FLAVORS SEG6_F_ATTR(SEG6_LOCAL_FLAVORS) > + > #define SEG6_F_LOCAL_FLV_OP(flvname) BIT(SEG6_LOCAL_FLV_OP_##flvname) > +#define SEG6_F_LOCAL_FLV_NEXT_CSID SEG6_F_LOCAL_FLV_OP(NEXT_CSID) > #define SEG6_F_LOCAL_FLV_PSP SEG6_F_LOCAL_FLV_OP(PSP) > > /* Supported RFC8986 Flavor operations are reported in this bitmask */ > #define SEG6_LOCAL_FLV8986_SUPP_OPS SEG6_F_LOCAL_FLV_PSP > > -/* Supported Flavor operations are reported in this bitmask */ > -#define SEG6_LOCAL_FLV_SUPP_OPS (SEG6_F_LOCAL_FLV_OP(NEXT_CSID) | \ > +#define SEG6_LOCAL_END_FLV_SUPP_OPS (SEG6_F_LOCAL_FLV_NEXT_CSID | \ > SEG6_LOCAL_FLV8986_SUPP_OPS) > +#define SEG6_LOCAL_END_X_FLV_SUPP_OPS SEG6_F_LOCAL_FLV_NEXT_CSID > > struct seg6_flavors_info { > /* Flavor operations */ > @@ -411,9 +415,72 @@ static int end_next_csid_core(struct sk_buff *skb, struct seg6_local_lwt *slwt) > return input_action_end_finish(skb, slwt); > } > > +static int input_action_end_x_finish(struct sk_buff *skb, > + struct seg6_local_lwt *slwt) > +{ > + seg6_lookup_nexthop(skb, &slwt->nh6, 0); > + > + return dst_input(skb); > +} > + > +static int input_action_end_x_core(struct sk_buff *skb, > + struct seg6_local_lwt *slwt) > +{ > + struct ipv6_sr_hdr *srh; > + > + srh = get_and_validate_srh(skb); > + if (!srh) > + goto drop; > + > + advance_nextseg(srh, &ipv6_hdr(skb)->daddr); > + > + return input_action_end_x_finish(skb, slwt); > + > +drop: > + kfree_skb(skb); > + return -EINVAL; > +} > + > +static int end_x_next_csid_core(struct sk_buff *skb, > + struct seg6_local_lwt *slwt) > +{ > + const struct seg6_flavors_info *finfo = &slwt->flv_info; > + struct in6_addr *daddr = &ipv6_hdr(skb)->daddr; > + > + if (seg6_next_csid_is_arg_zero(daddr, finfo)) > + return input_action_end_x_core(skb, slwt); > + > + /* update DA */ > + seg6_next_csid_advance_arg(daddr, finfo); > + > + return input_action_end_x_finish(skb, slwt); > +} > + > static bool seg6_next_csid_enabled(__u32 fops) > { > - return fops & BIT(SEG6_LOCAL_FLV_OP_NEXT_CSID); > + return fops & SEG6_F_LOCAL_FLV_NEXT_CSID; > +} > + > +/* Processing of SRv6 End, End.X, and End.T behaviors can be extended through > + * the flavors framework. These behaviors must report the subset of (flavor) > + * operations they currently implement. In this way, if a user specifies a > + * flavor combination that is not supported by a given End* behavior, the > + * kernel refuses to instantiate the tunnel reporting the error. > + */ > +static int seg6_flv_supp_ops_by_action(int action, __u32 *fops) > +{ > + switch (action) { > + case SEG6_LOCAL_ACTION_END: > + *fops = SEG6_LOCAL_END_FLV_SUPP_OPS; > + break; > + case SEG6_LOCAL_ACTION_END_X: > + *fops = SEG6_LOCAL_END_X_FLV_SUPP_OPS; > + break; > + default: > + return -EOPNOTSUPP; > + } > + > + return 0; > } > > /* We describe the packet state in relation to the absence/presence of the SRH > @@ -746,21 +813,14 @@ static int input_action_end(struct sk_buff *skb, struct seg6_local_lwt *slwt) > /* regular endpoint, and forward to specified nexthop */ > 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); > - if (!srh) > - goto drop; > - > - advance_nextseg(srh, &ipv6_hdr(skb)->daddr); > - > - seg6_lookup_nexthop(skb, &slwt->nh6, 0); > + const struct seg6_flavors_info *finfo = &slwt->flv_info; > + __u32 fops = finfo->flv_ops; > > - return dst_input(skb); > + /* check for the presence of NEXT-C-SID since it applies first */ > + if (seg6_next_csid_enabled(fops)) > + return end_x_next_csid_core(skb, slwt); > > -drop: > - kfree_skb(skb); > - return -EINVAL; > + return input_action_end_x_core(skb, slwt); > } > > static int input_action_end_t(struct sk_buff *skb, struct seg6_local_lwt *slwt) > @@ -1404,13 +1464,14 @@ static struct seg6_action_desc seg6_action_table[] = { > .action = SEG6_LOCAL_ACTION_END, > .attrs = 0, > .optattrs = SEG6_F_LOCAL_COUNTERS | > - SEG6_F_ATTR(SEG6_LOCAL_FLAVORS), > + SEG6_F_LOCAL_FLAVORS, > .input = input_action_end, > }, > { > .action = SEG6_LOCAL_ACTION_END_X, > .attrs = SEG6_F_ATTR(SEG6_LOCAL_NH6), > - .optattrs = SEG6_F_LOCAL_COUNTERS, > + .optattrs = SEG6_F_LOCAL_COUNTERS | > + SEG6_F_LOCAL_FLAVORS, > .input = input_action_end_x, > }, > { > @@ -2070,7 +2131,8 @@ static int parse_nla_flavors(struct nlattr **attrs, struct seg6_local_lwt *slwt, > { > struct seg6_flavors_info *finfo = &slwt->flv_info; > struct nlattr *tb[SEG6_LOCAL_FLV_MAX + 1]; > - unsigned long fops; > + int action = slwt->action; > + __u32 fops, supp_fops; > int rc; > > rc = nla_parse_nested_deprecated(tb, SEG6_LOCAL_FLV_MAX, > @@ -2086,7 +2148,8 @@ static int parse_nla_flavors(struct nlattr **attrs, struct seg6_local_lwt *slwt, > return -EINVAL; > > fops = nla_get_u32(tb[SEG6_LOCAL_FLV_OPERATION]); > - if (fops & ~SEG6_LOCAL_FLV_SUPP_OPS) { > + rc = seg6_flv_supp_ops_by_action(action, &supp_fops); > + if (rc < 0 || (fops & ~supp_fops)) { > NL_SET_ERR_MSG(extack, "Unsupported Flavor operation(s)"); > return -EOPNOTSUPP; > } > @@ -2618,6 +2681,11 @@ int __init seg6_local_init(void) > */ > BUILD_BUG_ON(SEG6_LOCAL_MAX + 1 > BITS_PER_TYPE(unsigned long)); > > + /* Check whether the number of defined flavors exceeds the maximum > + * allowed value. > + */ > + BUILD_BUG_ON(SEG6_LOCAL_FLV_OP_MAX + 1 > BITS_PER_TYPE(__u32)); > + > /* If the default NEXT-C-SID Locator-Block/Node Function lengths (in > * bits) have been changed with invalid values, kernel build stops > * here. > -- > 2.20.1 > Reviewed-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
