mpls: allow TTL propagation to IP packets to be configured
Provide the ability to control on a per-route basis whether the TTL value from an MPLS packet is propagated to an IPv4/IPv6 packet when the last label is popped as per the theoretical model in RFC 3443 through a new route attribute, RTA_TTL_PROPAGATE which can be 0 to mean disable propagation and 1 to mean enable propagation. In order to provide the ability to change the behaviour for packets arriving with IPv4/IPv6 Explicit Null labels and to provide an easy way for a user to change the behaviour for all existing routes without having to reprogram them, a global knob is provided. This is done through the addition of a new per-namespace sysctl, "net.mpls.ip_ttl_propagate", which defaults to enabled. If the per-route attribute is set (either enabled or disabled) then it overrides the global configuration. Signed-off-by: Robert Shearman <rshearma@brocade.com> Acked-by: David Ahern <dsa@cumulusnetworks.com> Tested-by: David Ahern <dsa@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Robert Shearman
David S. Miller
Родитель
b66239b682
Коммит
5b441ac878
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@ -19,6 +19,17 @@ platform_labels - INTEGER
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Possible values: 0 - 1048575
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Default: 0
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ip_ttl_propagate - BOOL
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Control whether TTL is propagated from the IPv4/IPv6 header to
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the MPLS header on imposing labels and propagated from the
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MPLS header to the IPv4/IPv6 header on popping the last label.
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If disabled, the MPLS transport network will appear as a
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single hop to transit traffic.
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0 - disabled / RFC 3443 [Short] Pipe Model
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1 - enabled / RFC 3443 Uniform Model (default)
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conf/<interface>/input - BOOL
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Control whether packets can be input on this interface.
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@ -9,8 +9,10 @@ struct mpls_route;
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struct ctl_table_header;
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struct netns_mpls {
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int ip_ttl_propagate;
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size_t platform_labels;
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struct mpls_route __rcu * __rcu *platform_label;
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struct ctl_table_header *ctl;
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};
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@ -319,6 +319,7 @@ enum rtattr_type_t {
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RTA_EXPIRES,
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RTA_PAD,
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RTA_UID,
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RTA_TTL_PROPAGATE,
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__RTA_MAX
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};
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@ -32,6 +32,7 @@
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#define MPLS_NEIGH_TABLE_UNSPEC (NEIGH_LINK_TABLE + 1)
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static int zero = 0;
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static int one = 1;
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static int label_limit = (1 << 20) - 1;
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static void rtmsg_lfib(int event, u32 label, struct mpls_route *rt,
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@ -220,8 +221,8 @@ out:
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return &rt->rt_nh[nh_index];
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}
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static bool mpls_egress(struct mpls_route *rt, struct sk_buff *skb,
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struct mpls_entry_decoded dec)
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static bool mpls_egress(struct net *net, struct mpls_route *rt,
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struct sk_buff *skb, struct mpls_entry_decoded dec)
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{
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enum mpls_payload_type payload_type;
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bool success = false;
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@ -246,22 +247,46 @@ static bool mpls_egress(struct mpls_route *rt, struct sk_buff *skb,
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switch (payload_type) {
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case MPT_IPV4: {
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struct iphdr *hdr4 = ip_hdr(skb);
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u8 new_ttl;
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skb->protocol = htons(ETH_P_IP);
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/* If propagating TTL, take the decremented TTL from
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* the incoming MPLS header, otherwise decrement the
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* TTL, but only if not 0 to avoid underflow.
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*/
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if (rt->rt_ttl_propagate == MPLS_TTL_PROP_ENABLED ||
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(rt->rt_ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
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net->mpls.ip_ttl_propagate))
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new_ttl = dec.ttl;
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else
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new_ttl = hdr4->ttl ? hdr4->ttl - 1 : 0;
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csum_replace2(&hdr4->check,
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htons(hdr4->ttl << 8),
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htons(dec.ttl << 8));
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hdr4->ttl = dec.ttl;
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htons(new_ttl << 8));
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hdr4->ttl = new_ttl;
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success = true;
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break;
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}
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case MPT_IPV6: {
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struct ipv6hdr *hdr6 = ipv6_hdr(skb);
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skb->protocol = htons(ETH_P_IPV6);
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hdr6->hop_limit = dec.ttl;
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/* If propagating TTL, take the decremented TTL from
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* the incoming MPLS header, otherwise decrement the
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* hop limit, but only if not 0 to avoid underflow.
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*/
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if (rt->rt_ttl_propagate == MPLS_TTL_PROP_ENABLED ||
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(rt->rt_ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
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net->mpls.ip_ttl_propagate))
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hdr6->hop_limit = dec.ttl;
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else if (hdr6->hop_limit)
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hdr6->hop_limit = hdr6->hop_limit - 1;
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success = true;
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break;
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}
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case MPT_UNSPEC:
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/* Should have decided which protocol it is by now */
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break;
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}
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@ -361,7 +386,7 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
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if (unlikely(!new_header_size && dec.bos)) {
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/* Penultimate hop popping */
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if (!mpls_egress(rt, skb, dec))
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if (!mpls_egress(dev_net(out_dev), rt, skb, dec))
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goto err;
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} else {
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bool bos;
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@ -412,6 +437,7 @@ static struct packet_type mpls_packet_type __read_mostly = {
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static const struct nla_policy rtm_mpls_policy[RTA_MAX+1] = {
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[RTA_DST] = { .type = NLA_U32 },
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[RTA_OIF] = { .type = NLA_U32 },
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[RTA_TTL_PROPAGATE] = { .type = NLA_U8 },
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};
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struct mpls_route_config {
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@ -421,6 +447,7 @@ struct mpls_route_config {
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u8 rc_via_alen;
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u8 rc_via[MAX_VIA_ALEN];
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u32 rc_label;
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u8 rc_ttl_propagate;
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u8 rc_output_labels;
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u32 rc_output_label[MAX_NEW_LABELS];
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u32 rc_nlflags;
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@ -856,6 +883,7 @@ static int mpls_route_add(struct mpls_route_config *cfg)
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rt->rt_protocol = cfg->rc_protocol;
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rt->rt_payload_type = cfg->rc_payload_type;
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rt->rt_ttl_propagate = cfg->rc_ttl_propagate;
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if (cfg->rc_mp)
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err = mpls_nh_build_multi(cfg, rt);
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@ -1576,6 +1604,7 @@ static int rtm_to_route_config(struct sk_buff *skb, struct nlmsghdr *nlh,
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cfg->rc_label = LABEL_NOT_SPECIFIED;
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cfg->rc_protocol = rtm->rtm_protocol;
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cfg->rc_via_table = MPLS_NEIGH_TABLE_UNSPEC;
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cfg->rc_ttl_propagate = MPLS_TTL_PROP_DEFAULT;
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cfg->rc_nlflags = nlh->nlmsg_flags;
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cfg->rc_nlinfo.portid = NETLINK_CB(skb).portid;
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cfg->rc_nlinfo.nlh = nlh;
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@ -1622,6 +1651,17 @@ static int rtm_to_route_config(struct sk_buff *skb, struct nlmsghdr *nlh,
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cfg->rc_mp_len = nla_len(nla);
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break;
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}
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case RTA_TTL_PROPAGATE:
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{
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u8 ttl_propagate = nla_get_u8(nla);
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if (ttl_propagate > 1)
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goto errout;
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cfg->rc_ttl_propagate = ttl_propagate ?
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MPLS_TTL_PROP_ENABLED :
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MPLS_TTL_PROP_DISABLED;
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break;
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}
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default:
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/* Unsupported attribute */
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goto errout;
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@ -1682,6 +1722,15 @@ static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
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if (nla_put_labels(skb, RTA_DST, 1, &label))
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goto nla_put_failure;
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if (rt->rt_ttl_propagate != MPLS_TTL_PROP_DEFAULT) {
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bool ttl_propagate =
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rt->rt_ttl_propagate == MPLS_TTL_PROP_ENABLED;
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if (nla_put_u8(skb, RTA_TTL_PROPAGATE,
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ttl_propagate))
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goto nla_put_failure;
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}
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if (rt->rt_nhn == 1) {
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const struct mpls_nh *nh = rt->rt_nh;
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@ -1792,7 +1841,8 @@ static inline size_t lfib_nlmsg_size(struct mpls_route *rt)
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{
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size_t payload =
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NLMSG_ALIGN(sizeof(struct rtmsg))
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+ nla_total_size(4); /* RTA_DST */
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+ nla_total_size(4) /* RTA_DST */
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+ nla_total_size(1); /* RTA_TTL_PROPAGATE */
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if (rt->rt_nhn == 1) {
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struct mpls_nh *nh = rt->rt_nh;
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@ -1876,6 +1926,7 @@ static int resize_platform_label_table(struct net *net, size_t limit)
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RCU_INIT_POINTER(rt0->rt_nh->nh_dev, lo);
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rt0->rt_protocol = RTPROT_KERNEL;
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rt0->rt_payload_type = MPT_IPV4;
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rt0->rt_ttl_propagate = MPLS_TTL_PROP_DEFAULT;
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rt0->rt_nh->nh_via_table = NEIGH_LINK_TABLE;
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rt0->rt_nh->nh_via_alen = lo->addr_len;
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memcpy(__mpls_nh_via(rt0, rt0->rt_nh), lo->dev_addr,
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@ -1889,6 +1940,7 @@ static int resize_platform_label_table(struct net *net, size_t limit)
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RCU_INIT_POINTER(rt2->rt_nh->nh_dev, lo);
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rt2->rt_protocol = RTPROT_KERNEL;
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rt2->rt_payload_type = MPT_IPV6;
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rt0->rt_ttl_propagate = MPLS_TTL_PROP_DEFAULT;
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rt2->rt_nh->nh_via_table = NEIGH_LINK_TABLE;
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rt2->rt_nh->nh_via_alen = lo->addr_len;
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memcpy(__mpls_nh_via(rt2, rt2->rt_nh), lo->dev_addr,
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@ -1970,6 +2022,9 @@ static int mpls_platform_labels(struct ctl_table *table, int write,
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return ret;
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}
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#define MPLS_NS_SYSCTL_OFFSET(field) \
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(&((struct net *)0)->field)
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static const struct ctl_table mpls_table[] = {
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{
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.procname = "platform_labels",
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@ -1978,21 +2033,37 @@ static const struct ctl_table mpls_table[] = {
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.mode = 0644,
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.proc_handler = mpls_platform_labels,
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},
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{
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.procname = "ip_ttl_propagate",
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.data = MPLS_NS_SYSCTL_OFFSET(mpls.ip_ttl_propagate),
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec_minmax,
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.extra1 = &zero,
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.extra2 = &one,
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},
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{ }
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};
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static int mpls_net_init(struct net *net)
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{
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struct ctl_table *table;
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int i;
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net->mpls.platform_labels = 0;
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net->mpls.platform_label = NULL;
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net->mpls.ip_ttl_propagate = 1;
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table = kmemdup(mpls_table, sizeof(mpls_table), GFP_KERNEL);
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if (table == NULL)
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return -ENOMEM;
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table[0].data = net;
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/* Table data contains only offsets relative to the base of
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* the mdev at this point, so make them absolute.
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*/
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for (i = 0; i < ARRAY_SIZE(mpls_table) - 1; i++)
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table[i].data = (char *)net + (uintptr_t)table[i].data;
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net->mpls.ctl = register_net_sysctl(net, "net/mpls", table);
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if (net->mpls.ctl == NULL) {
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kfree(table);
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@ -90,6 +90,12 @@ struct mpls_nh { /* next hop label forwarding entry */
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u8 nh_via_table;
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};
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enum mpls_ttl_propagation {
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MPLS_TTL_PROP_DEFAULT,
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MPLS_TTL_PROP_ENABLED,
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MPLS_TTL_PROP_DISABLED,
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};
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/* The route, nexthops and vias are stored together in the same memory
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* block:
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*
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@ -116,6 +122,7 @@ struct mpls_route { /* next hop label forwarding entry */
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u8 rt_protocol;
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u8 rt_payload_type;
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u8 rt_max_alen;
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u8 rt_ttl_propagate;
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unsigned int rt_nhn;
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unsigned int rt_nhn_alive;
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struct mpls_nh rt_nh[0];
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