Before this patch, a sniffer attached to a VRF used as the receiving interface of L3 tunneled packets detects them as malformed packets and it complains about that (i.e.: tcpdump shows bogus packets).

The reason is that a tunneled L3 packet does not carry any L2 information and when the VRF is set as the receiving interface of a decapsulated L3 packet, no mac header is currently set or valid. Therefore, the purpose of this patch consists of adding a MAC header to any packet which is directly received on the VRF interface ONLY IF:

i) a sniffer is attached on the VRF and ii) the mac header is not set.

In this case, the mac address of the VRF is copied in both the destination and the source address of the ethernet header. The protocol type is set either to IPv4 or IPv6, depending on which L3 packet is received.

Signed-off-by: Andrea Mayer andrea.mayer@uniroma2.it Reviewed-by: David Ahern dsahern@kernel.org --- drivers/net/vrf.c | 78 +++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 72 insertions(+), 6 deletions(-)

diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c index f8d711a84763..259d5cbacf2c 100644 --- a/drivers/net/vrf.c +++ b/drivers/net/vrf.c @@ -1310,6 +1310,61 @@ static void vrf_ip6_input_dst(struct sk_buff *skb, struct net_device *vrf_dev, skb_dst_set(skb, &rt6->dst); }

+static int vrf_prepare_mac_header(struct sk_buff *skb, + struct net_device *vrf_dev, u16 proto) +{ + struct ethhdr *eth; + int err; + + /* in general, we do not know if there is enough space in the head of + * the packet for hosting the mac header. + */ + err = skb_cow_head(skb, LL_RESERVED_SPACE(vrf_dev)); + if (unlikely(err)) + /* no space in the skb head */ + return -ENOBUFS; + + __skb_push(skb, ETH_HLEN); + eth = (struct ethhdr *)skb->data; + + skb_reset_mac_header(skb); + + /* we set the ethernet destination and the source addresses to the + * address of the VRF device. + */ + ether_addr_copy(eth->h_dest, vrf_dev->dev_addr); + ether_addr_copy(eth->h_source, vrf_dev->dev_addr); + eth->h_proto = htons(proto); + + /* the destination address of the Ethernet frame corresponds to the + * address set on the VRF interface; therefore, the packet is intended + * to be processed locally. + */ + skb->protocol = eth->h_proto; + skb->pkt_type = PACKET_HOST; + + skb_postpush_rcsum(skb, skb->data, ETH_HLEN); + + skb_pull_inline(skb, ETH_HLEN); + + return 0; +} + +/* prepare and add the mac header to the packet if it was not set previously. + * In this way, packet sniffers such as tcpdump can parse the packet correctly. + * If the mac header was already set, the original mac header is left + * untouched and the function returns immediately. + */ +static int vrf_add_mac_header_if_unset(struct sk_buff *skb, + struct net_device *vrf_dev, + u16 proto) +{ + if (skb_mac_header_was_set(skb)) + return 0; + + return vrf_prepare_mac_header(skb, vrf_dev, proto); +} + static struct sk_buff *vrf_ip6_rcv(struct net_device *vrf_dev, struct sk_buff *skb) { @@ -1336,9 +1391,15 @@ static struct sk_buff *vrf_ip6_rcv(struct net_device *vrf_dev, skb->skb_iif = vrf_dev->ifindex;

if (!list_empty(&vrf_dev->ptype_all)) { - skb_push(skb, skb->mac_len); - dev_queue_xmit_nit(skb, vrf_dev); - skb_pull(skb, skb->mac_len); + int err; + + err = vrf_add_mac_header_if_unset(skb, vrf_dev, + ETH_P_IPV6); + if (likely(!err)) { + skb_push(skb, skb->mac_len); + dev_queue_xmit_nit(skb, vrf_dev); + skb_pull(skb, skb->mac_len); + } }

IP6CB(skb)->flags |= IP6SKB_L3SLAVE; @@ -1381,9 +1442,14 @@ static struct sk_buff *vrf_ip_rcv(struct net_device *vrf_dev, vrf_rx_stats(vrf_dev, skb->len);

if (!list_empty(&vrf_dev->ptype_all)) { - skb_push(skb, skb->mac_len); - dev_queue_xmit_nit(skb, vrf_dev); - skb_pull(skb, skb->mac_len); + int err; + + err = vrf_add_mac_header_if_unset(skb, vrf_dev, ETH_P_IP); + if (likely(!err)) { + skb_push(skb, skb->mac_len); + dev_queue_xmit_nit(skb, vrf_dev); + skb_pull(skb, skb->mac_len); + } }

skb = vrf_rcv_nfhook(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, vrf_dev);

Before this patch, each SRv6 behavior specifies a set of required attributes that must be provided by the userspace application when such behavior is going to be instantiated. If at least one of the required attributes is not provided, the creation of the behavior fails.

The SRv6 behavior framework lacks a way to manage optional attributes. By definition, an optional attribute for a SRv6 behavior consists of an attribute which may or may not be provided by the userspace. Therefore, if an optional attribute is missing (and thus not supplied by the user) the creation of the behavior goes ahead without any issue.

This patch explicitly differentiates the required attributes from the optional attributes. In particular, each behavior can declare a set of required attributes and a set of optional ones.

The semantic of the required attributes remains *totally* unaffected by this patch. The introduction of the optional attributes does NOT impact on the backward compatibility of the existing SRv6 behaviors.

It is essential to note that if an (optional or required) attribute is supplied to a SRv6 behavior which does not expect it, the behavior simply discards such attribute without generating any error or warning. This operating mode remained unchanged both before and after the introduction of the optional attributes extension.

The optional attributes are one of the key components used to implement the SRv6 End.DT6 behavior based on the Virtual Routing and Forwarding (VRF) framework. The optional attributes make possible the coexistence of the already existing SRv6 End.DT6 implementation with the new SRv6 End.DT6 VRF-based implementation without breaking any backward compatibility. Further details on the SRv6 End.DT6 behavior (VRF mode) are reported in subsequent patches.

From the userspace point of view, the support for optional attributes DO

NOT require any changes to the userspace applications, i.e: iproute2 unless new attributes (required or optional) are needed.

Signed-off-by: Andrea Mayer andrea.mayer@uniroma2.it --- net/ipv6/seg6_local.c | 120 +++++++++++++++++++++++++++++++++++++----- 1 file changed, 106 insertions(+), 14 deletions(-)

diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c index aef39eab9be2..3b5657c622a0 100644 --- a/net/ipv6/seg6_local.c +++ b/net/ipv6/seg6_local.c @@ -36,6 +36,21 @@ struct seg6_local_lwt; struct seg6_action_desc { int action; unsigned long attrs; + + /* The optattrs field is used for specifying all the optional + * attributes supported by a specific behavior. + * It means that if one of these attributes is not provided in the + * netlink message during the behavior creation, no errors will be + * returned to the userspace. + * + * Each attribute can be only of two types (mutually exclusive): + * 1) required or 2) optional. + * Every user MUST obey to this rule! If you set an attribute as + * required the same attribute CANNOT be set as optional and vice + * versa. + */ + unsigned long optattrs; + int (*input)(struct sk_buff *skb, struct seg6_local_lwt *slwt); int static_headroom; }; @@ -57,6 +72,10 @@ struct seg6_local_lwt {

int headroom; struct seg6_action_desc *desc; + /* unlike the required attrs, we have to track the optional attributes + * that have been effectively parsed. + */ + unsigned long parsed_optattrs; };

static struct seg6_local_lwt *seg6_local_lwtunnel(struct lwtunnel_state *lwt) @@ -959,26 +978,26 @@ static struct seg6_action_param seg6_action_params[SEG6_LOCAL_MAX + 1] = { };

/* call the destroy() callback (if available) for each set attribute in - * @slwt, starting from the first attribute up to the @max_parsed (excluded) - * attribute. + * @parsed_attrs, starting from the first attribute up to the @max_parsed + * (excluded) attribute. */ -static void __destroy_attrs(int max_parsed, struct seg6_local_lwt *slwt) +static void __destroy_attrs(unsigned long parsed_attrs, int max_parsed, + struct seg6_local_lwt *slwt) { - unsigned long attrs = slwt->desc->attrs; struct seg6_action_param *param; int i;

/* Every required seg6local attribute is identified by an ID which is * encoded as a flag (i.e: 1 << ID) in the 'attrs' bitmask; * - * We scan the 'attrs' bitmask, starting from the first attribute + * We scan the 'parsed_attrs' bitmask, starting from the first attribute * up to the @max_parsed (excluded) attribute. * For each set attribute, we retrieve the corresponding destroy() * callback. If the callback is not available, then we skip to the next * attribute; otherwise, we call the destroy() callback. */ for (i = 0; i < max_parsed; ++i) { - if (!(attrs & (1 << i))) + if (!(parsed_attrs & (1 << i))) continue;

param = &seg6_action_params[i]; @@ -993,13 +1012,54 @@ static void __destroy_attrs(int max_parsed, struct seg6_local_lwt *slwt) */ static void destroy_attrs(struct seg6_local_lwt *slwt) { - __destroy_attrs(SEG6_LOCAL_MAX + 1, slwt); + unsigned long attrs = slwt->desc->attrs | slwt->parsed_optattrs; + + __destroy_attrs(attrs, SEG6_LOCAL_MAX + 1, slwt); +} + +static int parse_nla_optional_attrs(struct nlattr **attrs, + struct seg6_local_lwt *slwt) +{ + struct seg6_action_desc *desc = slwt->desc; + unsigned long parsed_optattrs = 0; + struct seg6_action_param *param; + int err, i; + + for (i = 0; i < SEG6_LOCAL_MAX + 1; ++i) { + if (!(desc->optattrs & (1 << i)) || !attrs[i]) + continue; + + /* once here, the i-th attribute is provided by the + * userspace AND it is identified optional as well. + */ + param = &seg6_action_params[i]; + + err = param->parse(attrs, slwt); + if (err < 0) + goto parse_optattrs_err; + + /* current attribute has been correctly parsed */ + parsed_optattrs |= (1 << i); + } + + /* store in the tunnel state all the optional attributed successfully + * parsed. + */ + slwt->parsed_optattrs = parsed_optattrs; + + return 0; + +parse_optattrs_err: + __destroy_attrs(parsed_optattrs, i, slwt); + + return err; }

static int parse_nla_action(struct nlattr **attrs, struct seg6_local_lwt *slwt) { struct seg6_action_param *param; struct seg6_action_desc *desc; + unsigned long invalid_attrs; int i, err;

desc = __get_action_desc(slwt->action); @@ -1012,6 +1072,26 @@ static int parse_nla_action(struct nlattr **attrs, struct seg6_local_lwt *slwt) slwt->desc = desc; slwt->headroom += desc->static_headroom;

+ /* Forcing the desc->optattrs *set* and the desc->attrs *set* to be + * disjoined, this allow us to release acquired resources by optional + * attributes and by required attributes independently from each other + * without any interfarence. + * In other terms, we are sure that we do not release some the acquired + * resources twice. + * + * Note that if an attribute is configured both as required and as + * optional, it means that the user has messed something up in the + * seg6_action_table. Therefore, this check is required for SRv6 + * behaviors to work properly. + */ + invalid_attrs = desc->attrs & desc->optattrs; + if (invalid_attrs) { + WARN_ONCE(1, + "An attribute cannot be both required AND optional"); + return -EINVAL; + } + + /* parse the required attributes */ for (i = 0; i < SEG6_LOCAL_MAX + 1; i++) { if (desc->attrs & (1 << i)) { if (!attrs[i]) @@ -1021,17 +1101,22 @@ static int parse_nla_action(struct nlattr **attrs, struct seg6_local_lwt *slwt)

err = param->parse(attrs, slwt); if (err < 0) - goto parse_err; + goto parse_attrs_err; } }

+ /* parse the optional attributes, if any */ + err = parse_nla_optional_attrs(attrs, slwt); + if (err < 0) + goto parse_attrs_err; + return 0;

-parse_err: +parse_attrs_err: /* release any resource that may have been acquired during the i-1 * parse() operations. */ - __destroy_attrs(i, slwt); + __destroy_attrs(desc->attrs, i, slwt);

return err; } @@ -1096,13 +1181,16 @@ static int seg6_local_fill_encap(struct sk_buff *skb, { struct seg6_local_lwt *slwt = seg6_local_lwtunnel(lwt); struct seg6_action_param *param; + unsigned long attrs; int i, err;

if (nla_put_u32(skb, SEG6_LOCAL_ACTION, slwt->action)) return -EMSGSIZE;

+ attrs = slwt->desc->attrs | slwt->parsed_optattrs; + for (i = 0; i < SEG6_LOCAL_MAX + 1; i++) { - if (slwt->desc->attrs & (1 << i)) { + if (attrs & (1 << i)) { param = &seg6_action_params[i]; err = param->put(skb, slwt); if (err < 0) @@ -1121,7 +1209,7 @@ static int seg6_local_get_encap_size(struct lwtunnel_state *lwt)

nlsize = nla_total_size(4); /* action */

- attrs = slwt->desc->attrs; + attrs = slwt->desc->attrs | slwt->parsed_optattrs;

if (attrs & (1 << SEG6_LOCAL_SRH)) nlsize += nla_total_size((slwt->srh->hdrlen + 1) << 3); @@ -1154,6 +1242,7 @@ static int seg6_local_cmp_encap(struct lwtunnel_state *a, { struct seg6_local_lwt *slwt_a, *slwt_b; struct seg6_action_param *param; + unsigned long attrs_a, attrs_b; int i;

slwt_a = seg6_local_lwtunnel(a); @@ -1162,11 +1251,14 @@ static int seg6_local_cmp_encap(struct lwtunnel_state *a, if (slwt_a->action != slwt_b->action) return 1;

- if (slwt_a->desc->attrs != slwt_b->desc->attrs) + attrs_a = slwt_a->desc->attrs | slwt_a->parsed_optattrs; + attrs_b = slwt_b->desc->attrs | slwt_b->parsed_optattrs; + + if (attrs_a != attrs_b) return 1;

for (i = 0; i < SEG6_LOCAL_MAX + 1; i++) { - if (slwt_a->desc->attrs & (1 << i)) { + if (attrs_a & (1 << i)) { param = &seg6_action_params[i]; if (param->cmp(slwt_a, slwt_b)) return 1;

SRv6 End.DT4 is defined in the SRv6 Network Programming [1].

The SRv6 End.DT4 is used to implement IPv4 L3VPN use-cases in multi-tenants environments. It decapsulates the received packets and it performs IPv4 routing lookup in the routing table of the tenant.

The SRv6 End.DT4 Linux implementation leverages a VRF device in order to force the routing lookup into the associated routing table.

To make the End.DT4 work properly, it must be guaranteed that the routing table used for routing lookup operations is bound to one and only one VRF during the tunnel creation. Such constraint has to be enforced by enabling the VRF strict_mode sysctl parameter, i.e: $ sysctl -wq net.vrf.strict_mode=1.

At JANOG44, LINE corporation presented their multi-tenant DC architecture using SRv6 [2]. In the slides, they reported that the Linux kernel is missing the support of SRv6 End.DT4 behavior.

The SRv6 End.DT4 behavior can be instantiated using a command similar to the following:

$ ip route add 2001:db8::1 encap seg6local action End.DT4 vrftable 100 dev eth0

We introduce the "vrftable" extension in iproute2 in a following patch.

[1] https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming [2] https://speakerdeck.com/line_developers/line-data-center-networking-with-srv...

Signed-off-by: Andrea Mayer andrea.mayer@uniroma2.it --- include/uapi/linux/seg6_local.h | 1 + net/ipv6/seg6_local.c | 287 ++++++++++++++++++++++++++++++++ 2 files changed, 288 insertions(+)

diff --git a/include/uapi/linux/seg6_local.h b/include/uapi/linux/seg6_local.h index edc138bdc56d..3b39ef1dbb46 100644 --- a/include/uapi/linux/seg6_local.h +++ b/include/uapi/linux/seg6_local.h @@ -26,6 +26,7 @@ enum { SEG6_LOCAL_IIF, SEG6_LOCAL_OIF, SEG6_LOCAL_BPF, + SEG6_LOCAL_VRFTABLE, __SEG6_LOCAL_MAX, }; #define SEG6_LOCAL_MAX (__SEG6_LOCAL_MAX - 1) diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c index da5bf4167a52..24c2616c8c11 100644 --- a/net/ipv6/seg6_local.c +++ b/net/ipv6/seg6_local.c @@ -69,6 +69,28 @@ struct bpf_lwt_prog { char *name; };

+enum seg6_end_dt_mode { + DT_INVALID_MODE = -EINVAL, + DT_LEGACY_MODE = 0, + DT_VRF_MODE = 1, +}; + +struct seg6_end_dt_info { + enum seg6_end_dt_mode mode; + + struct net *net; + /* VRF device associated to the routing table used by the SRv6 + * End.DT4/DT6 behavior for routing IPv4/IPv6 packets. + */ + int vrf_ifindex; + int vrf_table; + + /* tunneled packet proto and family (IPv4 or IPv6) */ + __be16 proto; + u16 family; + int hdrlen; +}; + struct seg6_local_lwt { int action; struct ipv6_sr_hdr *srh; @@ -78,6 +100,9 @@ struct seg6_local_lwt { int iif; int oif; struct bpf_lwt_prog bpf; +#ifdef CONFIG_NET_L3_MASTER_DEV + struct seg6_end_dt_info dt_info; +#endif

int headroom; struct seg6_action_desc *desc; @@ -429,6 +454,203 @@ static int input_action_end_dx4(struct sk_buff *skb, return -EINVAL; }

+#ifdef CONFIG_NET_L3_MASTER_DEV +static struct net *fib6_config_get_net(const struct fib6_config *fib6_cfg) +{ + const struct nl_info *nli = &fib6_cfg->fc_nlinfo; + + return nli->nl_net; +} + +static int __seg6_end_dt_vrf_build(struct seg6_local_lwt *slwt, const void *cfg, + u16 family, struct netlink_ext_ack *extack) +{ + struct seg6_end_dt_info *info = &slwt->dt_info; + int vrf_ifindex; + struct net *net; + + net = fib6_config_get_net(cfg); + + /* note that vrf_table was already set by parse_nla_vrftable() */ + vrf_ifindex = l3mdev_ifindex_lookup_by_table_id(L3MDEV_TYPE_VRF, net, + info->vrf_table); + if (vrf_ifindex < 0) { + if (vrf_ifindex == -EPERM) { + NL_SET_ERR_MSG(extack, + "Strict mode for VRF is disabled"); + } else if (vrf_ifindex == -ENODEV) { + NL_SET_ERR_MSG(extack, + "Table has no associated VRF device"); + } else { + pr_debug("seg6local: SRv6 End.DT* creation error=%d\n", + vrf_ifindex); + } + + return vrf_ifindex; + } + + info->net = net; + info->vrf_ifindex = vrf_ifindex; + + switch (family) { + case AF_INET: + info->proto = htons(ETH_P_IP); + info->hdrlen = sizeof(struct iphdr); + break; + default: + return -EINVAL; + } + + info->family = family; + info->mode = DT_VRF_MODE; + + return 0; +} + +/* The SRv6 End.DT4/DT6 behavior extracts the inner (IPv4/IPv6) packet and + * routes the IPv4/IPv6 packet by looking at the configured routing table. + * + * In the SRv6 End.DT4/DT6 use case, we can receive traffic (IPv6+Segment + * Routing Header packets) from several interfaces and the outer IPv6 + * destination address (DA) is used for retrieving the specific instance of the + * End.DT4/DT6 behavior that should process the packets. + * + * However, the inner IPv4/IPv6 packet is not really bound to any receiving + * interface and thus the End.DT4/DT6 sets the VRF (associated with the + * corresponding routing table) as the *receiving* interface. + * In other words, the End.DT4/DT6 processes a packet as if it has been received + * directly by the VRF (and not by one of its slave devices, if any). + * In this way, the VRF interface is used for routing the IPv4/IPv6 packet in + * according to the routing table configured by the End.DT4/DT6 instance. + * + * This design allows you to get some interesting features like: + * 1) the statistics on rx packets; + * 2) the possibility to install a packet sniffer on the receiving interface + * (the VRF one) for looking at the incoming packets; + * 3) the possibility to leverage the netfilter prerouting hook for the inner + * IPv4 packet. + * + * This function returns: + * - the sk_buff* when the VRF rcv handler has processed the packet correctly; + * - NULL when the skb is consumed by the VRF rcv handler; + * - a pointer which encodes a negative error number in case of error. + * Note that in this case, the function takes care of freeing the skb. + */ +static struct sk_buff *end_dt_vrf_rcv(struct sk_buff *skb, u16 family, + struct net_device *dev) +{ + /* based on l3mdev_ip_rcv; we are only interested in the master */ + if (unlikely(!netif_is_l3_master(dev) && !netif_has_l3_rx_handler(dev))) + goto drop; + + if (unlikely(!dev->l3mdev_ops->l3mdev_l3_rcv)) + goto drop; + + /* the decap packet IPv4/IPv6 does not come with any mac header info. + * We must unset the mac header to allow the VRF device to rebuild it, + * just in case there is a sniffer attached on the device. + */ + skb_unset_mac_header(skb); + + skb = dev->l3mdev_ops->l3mdev_l3_rcv(dev, skb, family); + if (!skb) + /* the skb buffer was consumed by the handler */ + return NULL; + + /* when a packet is received by a VRF or by one of its slaves, the + * master device reference is set into the skb. + */ + if (unlikely(skb->dev != dev || skb->skb_iif != dev->ifindex)) + goto drop; + + return skb; + +drop: + kfree_skb(skb); + return ERR_PTR(-EINVAL); +} + +static struct net_device *end_dt_get_vrf_rcu(struct sk_buff *skb, + struct seg6_end_dt_info *info) +{ + int vrf_ifindex = info->vrf_ifindex; + struct net *net = info->net; + + if (unlikely(vrf_ifindex < 0)) + goto error; + + if (unlikely(!net_eq(dev_net(skb->dev), net))) + goto error; + + return dev_get_by_index_rcu(net, vrf_ifindex); + +error: + return NULL; +} + +static struct sk_buff *end_dt_vrf_core(struct sk_buff *skb, + struct seg6_local_lwt *slwt) +{ + struct seg6_end_dt_info *info = &slwt->dt_info; + struct net_device *vrf; + + vrf = end_dt_get_vrf_rcu(skb, info); + if (unlikely(!vrf)) + goto drop; + + skb->protocol = info->proto; + + skb_dst_drop(skb); + + skb_set_transport_header(skb, info->hdrlen); + + return end_dt_vrf_rcv(skb, info->family, vrf); + +drop: + kfree_skb(skb); + return ERR_PTR(-EINVAL); +} + +static int input_action_end_dt4(struct sk_buff *skb, + struct seg6_local_lwt *slwt) +{ + struct iphdr *iph; + int err; + + if (!decap_and_validate(skb, IPPROTO_IPIP)) + goto drop; + + if (!pskb_may_pull(skb, sizeof(struct iphdr))) + goto drop; + + skb = end_dt_vrf_core(skb, slwt); + if (!skb) + /* packet has been processed and consumed by the VRF */ + return 0; + + if (IS_ERR(skb)) + return PTR_ERR(skb); + + iph = ip_hdr(skb); + + err = ip_route_input(skb, iph->daddr, iph->saddr, 0, skb->dev); + if (unlikely(err)) + goto drop; + + return dst_input(skb); + +drop: + kfree_skb(skb); + return -EINVAL; +} + +static int seg6_end_dt4_build(struct seg6_local_lwt *slwt, const void *cfg, + struct netlink_ext_ack *extack) +{ + return __seg6_end_dt_vrf_build(slwt, cfg, AF_INET, extack); +} +#endif + static int input_action_end_dt6(struct sk_buff *skb, struct seg6_local_lwt *slwt) { @@ -617,6 +839,16 @@ static struct seg6_action_desc seg6_action_table[] = { .attrs = (1 << SEG6_LOCAL_NH4), .input = input_action_end_dx4, }, + { + .action = SEG6_LOCAL_ACTION_END_DT4, + .attrs = (1 << SEG6_LOCAL_VRFTABLE), +#ifdef CONFIG_NET_L3_MASTER_DEV + .input = input_action_end_dt4, + .slwt_ops = { + .build_state = seg6_end_dt4_build, + }, +#endif + }, { .action = SEG6_LOCAL_ACTION_END_DT6, .attrs = (1 << SEG6_LOCAL_TABLE), @@ -677,6 +909,7 @@ static const struct nla_policy seg6_local_policy[SEG6_LOCAL_MAX + 1] = { [SEG6_LOCAL_ACTION] = { .type = NLA_U32 }, [SEG6_LOCAL_SRH] = { .type = NLA_BINARY }, [SEG6_LOCAL_TABLE] = { .type = NLA_U32 }, + [SEG6_LOCAL_VRFTABLE] = { .type = NLA_U32 }, [SEG6_LOCAL_NH4] = { .type = NLA_BINARY, .len = sizeof(struct in_addr) }, [SEG6_LOCAL_NH6] = { .type = NLA_BINARY, @@ -766,6 +999,53 @@ static int cmp_nla_table(struct seg6_local_lwt *a, struct seg6_local_lwt *b) return 0; }

+static struct +seg6_end_dt_info *seg6_possible_end_dt_info(struct seg6_local_lwt *slwt) +{ +#ifdef CONFIG_NET_L3_MASTER_DEV + return &slwt->dt_info; +#else + return ERR_PTR(-EOPNOTSUPP); +#endif +} + +static int parse_nla_vrftable(struct nlattr **attrs, + struct seg6_local_lwt *slwt) +{ + struct seg6_end_dt_info *info = seg6_possible_end_dt_info(slwt); + + if (IS_ERR(info)) + return PTR_ERR(info); + + info->vrf_table = nla_get_u32(attrs[SEG6_LOCAL_VRFTABLE]); + + return 0; +} + +static int put_nla_vrftable(struct sk_buff *skb, struct seg6_local_lwt *slwt) +{ + struct seg6_end_dt_info *info = seg6_possible_end_dt_info(slwt); + + if (IS_ERR(info)) + return PTR_ERR(info); + + if (nla_put_u32(skb, SEG6_LOCAL_VRFTABLE, info->vrf_table)) + return -EMSGSIZE; + + return 0; +} + +static int cmp_nla_vrftable(struct seg6_local_lwt *a, struct seg6_local_lwt *b) +{ + struct seg6_end_dt_info *info_a = seg6_possible_end_dt_info(a); + struct seg6_end_dt_info *info_b = seg6_possible_end_dt_info(b); + + if (info_a->vrf_table != info_b->vrf_table) + return 1; + + return 0; +} + static int parse_nla_nh4(struct nlattr **attrs, struct seg6_local_lwt *slwt) { memcpy(&slwt->nh4, nla_data(attrs[SEG6_LOCAL_NH4]), @@ -984,6 +1264,10 @@ static struct seg6_action_param seg6_action_params[SEG6_LOCAL_MAX + 1] = { .cmp = cmp_nla_bpf, .destroy = destroy_attr_bpf },

+ [SEG6_LOCAL_VRFTABLE] = { .parse = parse_nla_vrftable, + .put = put_nla_vrftable, + .cmp = cmp_nla_vrftable }, + };

/* call the destroy() callback (if available) for each set attribute in @@ -1283,6 +1567,9 @@ static int seg6_local_get_encap_size(struct lwtunnel_state *lwt) nla_total_size(MAX_PROG_NAME) + nla_total_size(4);

+ if (attrs & (1 << SEG6_LOCAL_VRFTABLE)) + nlsize += nla_total_size(4); + return nlsize; }

this selftest is designed for evaluating the new SRv6 End.DT4 behavior used, in this example, for implementing IPv4 L3 VPN use cases.

Signed-off-by: Andrea Mayer andrea.mayer@uniroma2.it Reviewed-by: David Ahern dsahern@kernel.org --- .../selftests/net/srv6_end_dt4_l3vpn_test.sh | 494 ++++++++++++++++++ 1 file changed, 494 insertions(+) create mode 100755 tools/testing/selftests/net/srv6_end_dt4_l3vpn_test.sh

diff --git a/tools/testing/selftests/net/srv6_end_dt4_l3vpn_test.sh b/tools/testing/selftests/net/srv6_end_dt4_l3vpn_test.sh new file mode 100755 index 000000000000..ad7a9fc59934 --- /dev/null +++ b/tools/testing/selftests/net/srv6_end_dt4_l3vpn_test.sh @@ -0,0 +1,494 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# author: Andrea Mayer andrea.mayer@uniroma2.it + +# This test is designed for evaluating the new SRv6 End.DT4 behavior used for +# implementing IPv4 L3 VPN use cases. +# +# Hereafter a network diagram is shown, where two different tenants (named 100 +# and 200) offer IPv4 L3 VPN services allowing hosts to communicate with each +# other across an IPv6 network. +# +# Only hosts belonging to the same tenant (and to the same VPN) can communicate +# with each other. Instead, the communication among hosts of different tenants +# is forbidden. +# In other words, hosts hs-t100-1 and hs-t100-2 are connected through the IPv4 +# L3 VPN of tenant 100 while hs-t200-3 and hs-t200-4 are connected using the +# IPv4 L3 VPN of tenant 200. Cross connection between tenant 100 and tenant 200 +# is forbidden and thus, for example, hs-t100-1 cannot reach hs-t200-3 and vice +# versa. +# +# Routers rt-1 and rt-2 implement IPv4 L3 VPN services leveraging the SRv6 +# architecture. The key components for such VPNs are: a) SRv6 Encap behavior, +# b) SRv6 End.DT4 behavior and c) VRF. +# +# To explain how an IPv4 L3 VPN based on SRv6 works, let us briefly consider an +# example where, within the same domain of tenant 100, the host hs-t100-1 pings +# the host hs-t100-2. +# +# First of all, L2 reachability of the host hs-t100-2 is taken into account by +# the router rt-1 which acts as an arp proxy. +# +# When the host hs-t100-1 sends an IPv4 packet destined to hs-t100-2, the +# router rt-1 receives the packet on the internal veth-t100 interface. Such +# interface is enslaved to the VRF vrf-100 whose associated table contains the +# SRv6 Encap route for encapsulating any IPv4 packet in a IPv6 plus the Segment +# Routing Header (SRH) packet. This packet is sent through the (IPv6) core +# network up to the router rt-2 that receives it on veth0 interface. +# +# The rt-2 router uses the 'localsid' routing table to process incoming +# IPv6+SRH packets which belong to the VPN of the tenant 100. For each of these +# packets, the SRv6 End.DT4 behavior removes the outer IPv6+SRH headers and +# performs the lookup on the vrf-100 table using the destination address of +# the decapsulated IPv4 packet. Afterwards, the packet is sent to the host +# hs-t100-2 through the veth-t100 interface. +# +# The ping response follows the same processing but this time the role of rt-1 +# and rt-2 are swapped. +# +# Of course, the IPv4 L3 VPN for tenant 200 works exactly as the IPv4 L3 VPN +# for tenant 100. In this case, only hosts hs-t200-3 and hs-t200-4 are able to +# connect with each other. +# +# +# +-------------------+ +-------------------+ +# | | | | +# | hs-t100-1 netns | | hs-t100-2 netns | +# | | | | +# | +-------------+ | | +-------------+ | +# | | veth0 | | | | veth0 | | +# | | 10.0.0.1/24 | | | | 10.0.0.2/24 | | +# | +-------------+ | | +-------------+ | +# | . | | . | +# +-------------------+ +-------------------+ +# . . +# . . +# . . +# +-----------------------------------+ +-----------------------------------+ +# | . | | . | +# | +---------------+ | | +---------------- | +# | | veth-t100 | | | | veth-t100 | | +# | | 10.0.0.254/24 | +----------+ | | +----------+ | 10.0.0.254/24 | | +# | +-------+-------+ | localsid | | | | localsid | +-------+-------- | +# | | | table | | | | table | | | +# | +----+----+ +----------+ | | +----------+ +----+----+ | +# | | vrf-100 | | | | vrf-100 | | +# | +---------+ +------------+ | | +------------+ +---------+ | +# | | veth0 | | | | veth0 | | +# | | fd00::1/64 |.|...|.| fd00::2/64 | | +# | +---------+ +------------+ | | +------------+ +---------+ | +# | | vrf-200 | | | | vrf-200 | | +# | +----+----+ | | +----+----+ | +# | | | | | | +# | +-------+-------+ | | +-------+-------- | +# | | veth-t200 | | | | veth-t200 | | +# | | 10.0.0.254/24 | | | | 10.0.0.254/24 | | +# | +---------------+ rt-1 netns | | rt-2 netns +---------------- | +# | . | | . | +# +-----------------------------------+ +-----------------------------------+ +# . . +# . . +# . . +# . . +# +-------------------+ +-------------------+ +# | . | | . | +# | +-------------+ | | +-------------+ | +# | | veth0 | | | | veth0 | | +# | | 10.0.0.3/24 | | | | 10.0.0.4/24 | | +# | +-------------+ | | +-------------+ | +# | | | | +# | hs-t200-3 netns | | hs-t200-4 netns | +# | | | | +# +-------------------+ +-------------------+ +# +# +# ~~~~~~~~~~~~~~~~~~~~~~~~~ +# | Network configuration | +# ~~~~~~~~~~~~~~~~~~~~~~~~~ +# +# rt-1: localsid table (table 90) +# +-------------------------------------------------+ +# |SID |Action | +# +-------------------------------------------------+ +# |fc00:21:100::6004|apply SRv6 End.DT4 vrftable 100| +# +-------------------------------------------------+ +# |fc00:21:200::6004|apply SRv6 End.DT4 vrftable 200| +# +-------------------------------------------------+ +# +# rt-1: VRF tenant 100 (table 100) +# +---------------------------------------------------+ +# |host |Action | +# +---------------------------------------------------+ +# |10.0.0.2 |apply seg6 encap segs fc00:12:100::6004| +# +---------------------------------------------------+ +# |10.0.0.0/24|forward to dev veth_t100 | +# +---------------------------------------------------+ +# +# rt-1: VRF tenant 200 (table 200) +# +---------------------------------------------------+ +# |host |Action | +# +---------------------------------------------------+ +# |10.0.0.4 |apply seg6 encap segs fc00:12:200::6004| +# +---------------------------------------------------+ +# |10.0.0.0/24|forward to dev veth_t200 | +# +---------------------------------------------------+ +# +# +# rt-2: localsid table (table 90) +# +-------------------------------------------------+ +# |SID |Action | +# +-------------------------------------------------+ +# |fc00:12:100::6004|apply SRv6 End.DT4 vrftable 100| +# +-------------------------------------------------+ +# |fc00:12:200::6004|apply SRv6 End.DT4 vrftable 200| +# +-------------------------------------------------+ +# +# rt-2: VRF tenant 100 (table 100) +# +---------------------------------------------------+ +# |host |Action | +# +---------------------------------------------------+ +# |10.0.0.1 |apply seg6 encap segs fc00:21:100::6004| +# +---------------------------------------------------+ +# |10.0.0.0/24|forward to dev veth_t100 | +# +---------------------------------------------------+ +# +# rt-2: VRF tenant 200 (table 200) +# +---------------------------------------------------+ +# |host |Action | +# +---------------------------------------------------+ +# |10.0.0.3 |apply seg6 encap segs fc00:21:200::6004| +# +---------------------------------------------------+ +# |10.0.0.0/24|forward to dev veth_t200 | +# +---------------------------------------------------+ +# + +readonly LOCALSID_TABLE_ID=90 +readonly IPv6_RT_NETWORK=fd00 +readonly IPv4_HS_NETWORK=10.0.0 +readonly VPN_LOCATOR_SERVICE=fc00 +PING_TIMEOUT_SEC=4 + +ret=0 + +PAUSE_ON_FAIL=${PAUSE_ON_FAIL:=no} + +log_test() +{ + local rc=$1 + local expected=$2 + local msg="$3" + + if [ ${rc} -eq ${expected} ]; then + nsuccess=$((nsuccess+1)) + printf "\n TEST: %-60s [ OK ]\n" "${msg}" + else + ret=1 + nfail=$((nfail+1)) + printf "\n TEST: %-60s [FAIL]\n" "${msg}" + if [ "${PAUSE_ON_FAIL}" = "yes" ]; then + echo + echo "hit enter to continue, 'q' to quit" + read a + [ "$a" = "q" ] && exit 1 + fi + fi +} + +print_log_test_results() +{ + if [ "$TESTS" != "none" ]; then + printf "\nTests passed: %3d\n" ${nsuccess} + printf "Tests failed: %3d\n" ${nfail} + fi +} + +log_section() +{ + echo + echo "################################################################################" + echo "TEST SECTION: $*" + echo "################################################################################" +} + +cleanup() +{ + ip link del veth-rt-1 2>/dev/null || true + ip link del veth-rt-2 2>/dev/null || true + + # destroy routers rt-* and hosts hs-* + for ns in $(ip netns show | grep -E 'rt-*|hs-*'); do + ip netns del ${ns} || true + done +} + +# Setup the basic networking for the routers +setup_rt_networking() +{ + local rt=$1 + local nsname=rt-${rt} + + ip netns add ${nsname} + ip link set veth-rt-${rt} netns ${nsname} + ip -netns ${nsname} link set veth-rt-${rt} name veth0 + + ip -netns ${nsname} addr add ${IPv6_RT_NETWORK}::${rt}/64 dev veth0 + ip -netns ${nsname} link set veth0 up + ip -netns ${nsname} link set lo up + + ip netns exec ${nsname} sysctl -wq net.ipv4.ip_forward=1 + ip netns exec ${nsname} sysctl -wq net.ipv6.conf.all.forwarding=1 +} + +setup_hs() +{ + local hs=$1 + local rt=$2 + local tid=$3 + local hsname=hs-t${tid}-${hs} + local rtname=rt-${rt} + local rtveth=veth-t${tid} + + # set the networking for the host + ip netns add ${hsname} + ip -netns ${hsname} link add veth0 type veth peer name ${rtveth} + ip -netns ${hsname} link set ${rtveth} netns ${rtname} + ip -netns ${hsname} addr add ${IPv4_HS_NETWORK}.${hs}/24 dev veth0 + ip -netns ${hsname} link set veth0 up + ip -netns ${hsname} link set lo up + + # configure the VRF for the tenant X on the router which is directly + # connected to the source host. + ip -netns ${rtname} link add vrf-${tid} type vrf table ${tid} + ip -netns ${rtname} link set vrf-${tid} up + + # enslave the veth-tX interface to the vrf-X in the access router + ip -netns ${rtname} link set ${rtveth} master vrf-${tid} + ip -netns ${rtname} addr add ${IPv4_HS_NETWORK}.254/24 dev ${rtveth} + ip -netns ${rtname} link set ${rtveth} up + + ip netns exec ${rtname} sysctl -wq net.ipv4.conf.${rtveth}.proxy_arp=1 + + # disable the rp_filter otherwise the kernel gets confused about how + # to route decap ipv4 packets. + ip netns exec ${rtname} sysctl -wq net.ipv4.conf.all.rp_filter=0 + ip netns exec ${rtname} sysctl -wq net.ipv4.conf.${rtveth}.rp_filter=0 + + ip netns exec ${rtname} sh -c "echo 1 > /proc/sys/net/vrf/strict_mode" +} + +setup_vpn_config() +{ + local hssrc=$1 + local rtsrc=$2 + local hsdst=$3 + local rtdst=$4 + local tid=$5 + + local hssrc_name=hs-t${tid}-${hssrc} + local hsdst_name=hs-t${tid}-${hsdst} + local rtsrc_name=rt-${rtsrc} + local rtdst_name=rt-${rtdst} + local vpn_sid=${VPN_LOCATOR_SERVICE}:${hssrc}${hsdst}:${tid}::6004 + + # set the encap route for encapsulating packets which arrive from the + # host hssrc and destined to the access router rtsrc. + ip -netns ${rtsrc_name} -4 route add ${IPv4_HS_NETWORK}.${hsdst}/32 vrf vrf-${tid} \ + encap seg6 mode encap segs ${vpn_sid} dev veth0 + ip -netns ${rtsrc_name} -6 route add ${vpn_sid}/128 vrf vrf-${tid} \ + via fd00::${rtdst} dev veth0 + + # set the decap route for decapsulating packets which arrive from + # the rtdst router and destined to the hsdst host. + ip -netns ${rtdst_name} -6 route add ${vpn_sid}/128 table ${LOCALSID_TABLE_ID} \ + encap seg6local action End.DT4 vrftable ${tid} dev vrf-${tid} + + # all sids for VPNs start with a common locator which is fc00::/16. + # Routes for handling the SRv6 End.DT4 behavior instances are grouped + # together in the 'localsid' table. + # + # NOTE: added only once + if [ -z "$(ip -netns ${rtdst_name} -6 rule show | \ + grep "to ${VPN_LOCATOR_SERVICE}::/16 lookup ${LOCALSID_TABLE_ID}")" ]; then + ip -netns ${rtdst_name} -6 rule add \ + to ${VPN_LOCATOR_SERVICE}::/16 \ + lookup ${LOCALSID_TABLE_ID} prio 999 + fi +} + +setup() +{ + ip link add veth-rt-1 type veth peer name veth-rt-2 + # setup the networking for router rt-1 and router rt-2 + setup_rt_networking 1 + setup_rt_networking 2 + + # setup two hosts for the tenant 100. + # - host hs-1 is directly connected to the router rt-1; + # - host hs-2 is directly connected to the router rt-2. + setup_hs 1 1 100 #args: host router tenant + setup_hs 2 2 100 + + # setup two hosts for the tenant 200 + # - host hs-3 is directly connected to the router rt-1; + # - host hs-4 is directly connected to the router rt-2. + setup_hs 3 1 200 + setup_hs 4 2 200 + + # setup the IPv4 L3 VPN which connects the host hs-t100-1 and host + # hs-t100-2 within the same tenant 100. + setup_vpn_config 1 1 2 2 100 #args: src_host src_router dst_host dst_router tenant + setup_vpn_config 2 2 1 1 100 + + # setup the IPv4 L3 VPN which connects the host hs-t200-3 and host + # hs-t200-4 within the same tenant 200. + setup_vpn_config 3 1 4 2 200 + setup_vpn_config 4 2 3 1 200 +} + +check_rt_connectivity() +{ + local rtsrc=$1 + local rtdst=$2 + + ip netns exec rt-${rtsrc} ping -c 1 -W 1 ${IPv6_RT_NETWORK}::${rtdst} \ + >/dev/null 2>&1 +} + +check_and_log_rt_connectivity() +{ + local rtsrc=$1 + local rtdst=$2 + + check_rt_connectivity ${rtsrc} ${rtdst} + log_test $? 0 "Routers connectivity: rt-${rtsrc} -> rt-${rtdst}" +} + +check_hs_connectivity() +{ + local hssrc=$1 + local hsdst=$2 + local tid=$3 + + ip netns exec hs-t${tid}-${hssrc} ping -c 1 -W ${PING_TIMEOUT_SEC} \ + ${IPv4_HS_NETWORK}.${hsdst} >/dev/null 2>&1 +} + +check_and_log_hs_connectivity() +{ + local hssrc=$1 + local hsdst=$2 + local tid=$3 + + check_hs_connectivity ${hssrc} ${hsdst} ${tid} + log_test $? 0 "Hosts connectivity: hs-t${tid}-${hssrc} -> hs-t${tid}-${hsdst} (tenant ${tid})" +} + +check_and_log_hs_isolation() +{ + local hssrc=$1 + local tidsrc=$2 + local hsdst=$3 + local tiddst=$4 + + check_hs_connectivity ${hssrc} ${hsdst} ${tidsrc} + # NOTE: ping should fail + log_test $? 1 "Hosts isolation: hs-t${tidsrc}-${hssrc} -X-> hs-t${tiddst}-${hsdst}" +} + + +check_and_log_hs2gw_connectivity() +{ + local hssrc=$1 + local tid=$2 + + check_hs_connectivity ${hssrc} 254 ${tid} + log_test $? 0 "Hosts connectivity: hs-t${tid}-${hssrc} -> gw (tenant ${tid})" +} + +router_tests() +{ + log_section "IPv6 routers connectivity test" + + check_and_log_rt_connectivity 1 2 + check_and_log_rt_connectivity 2 1 +} + +host2gateway_tests() +{ + log_section "IPv4 connectivity test among hosts and gateway" + + check_and_log_hs2gw_connectivity 1 100 + check_and_log_hs2gw_connectivity 2 100 + + check_and_log_hs2gw_connectivity 3 200 + check_and_log_hs2gw_connectivity 4 200 +} + +host_vpn_tests() +{ + log_section "SRv6 VPN connectivity test among hosts in the same tenant" + + check_and_log_hs_connectivity 1 2 100 + check_and_log_hs_connectivity 2 1 100 + + check_and_log_hs_connectivity 3 4 200 + check_and_log_hs_connectivity 4 3 200 +} + +host_vpn_isolation_tests() +{ + local i + local j + local k + local tmp + local l1="1 2" + local l2="3 4" + local t1=100 + local t2=200 + + log_section "SRv6 VPN isolation test among hosts in different tentants" + + for k in 0 1; do + for i in ${l1}; do + for j in ${l2}; do + check_and_log_hs_isolation ${i} ${t1} ${j} ${t2} + done + done + + # let us test the reverse path + tmp="${l1}"; l1="${l2}"; l2="${tmp}" + tmp=${t1}; t1=${t2}; t2=${tmp} + done +} + +if [ "$(id -u)" -ne 0 ];then + echo "SKIP: Need root privileges" + exit 0 +fi + +if [ ! -x "$(command -v ip)" ]; then + echo "SKIP: Could not run test without ip tool" + exit 0 +fi + +modprobe vrf &>/dev/null +if [ ! -e /proc/sys/net/vrf/strict_mode ]; then + echo "SKIP: vrf sysctl does not exist" + exit 0 +fi + +cleanup &>/dev/null + +setup + +router_tests +host2gateway_tests +host_vpn_tests +host_vpn_isolation_tests + +print_log_test_results + +cleanup &>/dev/null + +exit ${ret}