From 4895c771c7f006b4b90f9d6b1d2210939ba57b38 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Tue, 17 Jul 2012 04:19:00 -0700 Subject: [PATCH] ipv4: Add FIB nexthop exceptions. In a regime where we have subnetted route entries, we need a way to store persistent storage about destination specific learned values such as redirects and PMTU values. This is implemented here via nexthop exceptions. The initial implementation is a 2048 entry hash table with relaiming starting at chain length 5. A more sophisticated scheme can be devised if that proves necessary. Signed-off-by: David S. Miller --- include/net/ip_fib.h | 18 +++ net/ipv4/fib_semantics.c | 23 ++++ net/ipv4/route.c | 256 ++++++++++++++++++++++++++++++++++----- 3 files changed, 266 insertions(+), 31 deletions(-) diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h index 5697acefeba3..e9ee1ca07087 100644 --- a/include/net/ip_fib.h +++ b/include/net/ip_fib.h @@ -18,6 +18,7 @@ #include #include +#include #include #include @@ -46,6 +47,22 @@ struct fib_config { struct fib_info; +struct fib_nh_exception { + struct fib_nh_exception __rcu *fnhe_next; + __be32 fnhe_daddr; + u32 fnhe_pmtu; + u32 fnhe_gw; + unsigned long fnhe_expires; + unsigned long fnhe_stamp; +}; + +struct fnhe_hash_bucket { + struct fib_nh_exception __rcu *chain; +}; + +#define FNHE_HASH_SIZE 2048 +#define FNHE_RECLAIM_DEPTH 5 + struct fib_nh { struct net_device *nh_dev; struct hlist_node nh_hash; @@ -63,6 +80,7 @@ struct fib_nh { __be32 nh_gw; __be32 nh_saddr; int nh_saddr_genid; + struct fnhe_hash_bucket *nh_exceptions; }; /* diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c index d71bfbdc0bf4..1e09852df512 100644 --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -140,6 +140,27 @@ const struct fib_prop fib_props[RTN_MAX + 1] = { }, }; +static void free_nh_exceptions(struct fib_nh *nh) +{ + struct fnhe_hash_bucket *hash = nh->nh_exceptions; + int i; + + for (i = 0; i < FNHE_HASH_SIZE; i++) { + struct fib_nh_exception *fnhe; + + fnhe = rcu_dereference(hash[i].chain); + while (fnhe) { + struct fib_nh_exception *next; + + next = rcu_dereference(fnhe->fnhe_next); + kfree(fnhe); + + fnhe = next; + } + } + kfree(hash); +} + /* Release a nexthop info record */ static void free_fib_info_rcu(struct rcu_head *head) { @@ -148,6 +169,8 @@ static void free_fib_info_rcu(struct rcu_head *head) change_nexthops(fi) { if (nexthop_nh->nh_dev) dev_put(nexthop_nh->nh_dev); + if (nexthop_nh->nh_exceptions) + free_nh_exceptions(nexthop_nh); } endfor_nexthops(fi); release_net(fi->fib_net); diff --git a/net/ipv4/route.c b/net/ipv4/route.c index b35d3bfc66cd..a5bd0b4acc61 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1275,14 +1275,130 @@ static void rt_del(unsigned int hash, struct rtable *rt) spin_unlock_bh(rt_hash_lock_addr(hash)); } -static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb) +static void __build_flow_key(struct flowi4 *fl4, struct sock *sk, + const struct iphdr *iph, + int oif, u8 tos, + u8 prot, u32 mark, int flow_flags) +{ + if (sk) { + const struct inet_sock *inet = inet_sk(sk); + + oif = sk->sk_bound_dev_if; + mark = sk->sk_mark; + tos = RT_CONN_FLAGS(sk); + prot = inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol; + } + flowi4_init_output(fl4, oif, mark, tos, + RT_SCOPE_UNIVERSE, prot, + flow_flags, + iph->daddr, iph->saddr, 0, 0); +} + +static void build_skb_flow_key(struct flowi4 *fl4, struct sk_buff *skb, struct sock *sk) +{ + const struct iphdr *iph = ip_hdr(skb); + int oif = skb->dev->ifindex; + u8 tos = RT_TOS(iph->tos); + u8 prot = iph->protocol; + u32 mark = skb->mark; + + __build_flow_key(fl4, sk, iph, oif, tos, prot, mark, 0); +} + +static void build_sk_flow_key(struct flowi4 *fl4, struct sock *sk) +{ + const struct inet_sock *inet = inet_sk(sk); + struct ip_options_rcu *inet_opt; + __be32 daddr = inet->inet_daddr; + + rcu_read_lock(); + inet_opt = rcu_dereference(inet->inet_opt); + if (inet_opt && inet_opt->opt.srr) + daddr = inet_opt->opt.faddr; + flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark, + RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE, + inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol, + inet_sk_flowi_flags(sk), + daddr, inet->inet_saddr, 0, 0); + rcu_read_unlock(); +} + +static void ip_rt_build_flow_key(struct flowi4 *fl4, struct sock *sk, + struct sk_buff *skb) +{ + if (skb) + build_skb_flow_key(fl4, skb, sk); + else + build_sk_flow_key(fl4, sk); +} + +static DEFINE_SPINLOCK(fnhe_lock); + +static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash, __be32 daddr) +{ + struct fib_nh_exception *fnhe, *oldest; + + oldest = rcu_dereference(hash->chain); + for (fnhe = rcu_dereference(oldest->fnhe_next); fnhe; + fnhe = rcu_dereference(fnhe->fnhe_next)) { + if (time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp)) + oldest = fnhe; + } + return oldest; +} + +static struct fib_nh_exception *find_or_create_fnhe(struct fib_nh *nh, __be32 daddr) +{ + struct fnhe_hash_bucket *hash = nh->nh_exceptions; + struct fib_nh_exception *fnhe; + int depth; + u32 hval; + + if (!hash) { + hash = nh->nh_exceptions = kzalloc(FNHE_HASH_SIZE * sizeof(*hash), + GFP_ATOMIC); + if (!hash) + return NULL; + } + + hval = (__force u32) daddr; + hval ^= (hval >> 11) ^ (hval >> 22); + hash += hval; + + depth = 0; + for (fnhe = rcu_dereference(hash->chain); fnhe; + fnhe = rcu_dereference(fnhe->fnhe_next)) { + if (fnhe->fnhe_daddr == daddr) + goto out; + depth++; + } + + if (depth > FNHE_RECLAIM_DEPTH) { + fnhe = fnhe_oldest(hash + hval, daddr); + goto out_daddr; + } + fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC); + if (!fnhe) + return NULL; + + fnhe->fnhe_next = hash->chain; + rcu_assign_pointer(hash->chain, fnhe); + +out_daddr: + fnhe->fnhe_daddr = daddr; +out: + fnhe->fnhe_stamp = jiffies; + return fnhe; +} + +static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4) { __be32 new_gw = icmp_hdr(skb)->un.gateway; __be32 old_gw = ip_hdr(skb)->saddr; struct net_device *dev = skb->dev; struct in_device *in_dev; + struct fib_result res; struct neighbour *n; - struct rtable *rt; struct net *net; switch (icmp_hdr(skb)->code & 7) { @@ -1296,7 +1412,6 @@ static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buf return; } - rt = (struct rtable *) dst; if (rt->rt_gateway != old_gw) return; @@ -1320,11 +1435,21 @@ static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buf goto reject_redirect; } - n = ipv4_neigh_lookup(dst, NULL, &new_gw); + n = ipv4_neigh_lookup(&rt->dst, NULL, &new_gw); if (n) { if (!(n->nud_state & NUD_VALID)) { neigh_event_send(n, NULL); } else { + if (fib_lookup(net, fl4, &res) == 0) { + struct fib_nh *nh = &FIB_RES_NH(res); + struct fib_nh_exception *fnhe; + + spin_lock_bh(&fnhe_lock); + fnhe = find_or_create_fnhe(nh, fl4->daddr); + if (fnhe) + fnhe->fnhe_gw = new_gw; + spin_unlock_bh(&fnhe_lock); + } rt->rt_gateway = new_gw; rt->rt_flags |= RTCF_REDIRECTED; call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n); @@ -1349,6 +1474,17 @@ reject_redirect: ; } +static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb) +{ + struct rtable *rt; + struct flowi4 fl4; + + rt = (struct rtable *) dst; + + ip_rt_build_flow_key(&fl4, sk, skb); + __ip_do_redirect(rt, skb, &fl4); +} + static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst) { struct rtable *rt = (struct rtable *)dst; @@ -1508,33 +1644,51 @@ out: kfree_skb(skb); return 0; } -static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk, - struct sk_buff *skb, u32 mtu) +static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) { - struct rtable *rt = (struct rtable *) dst; - - dst_confirm(dst); + struct fib_result res; if (mtu < ip_rt_min_pmtu) mtu = ip_rt_min_pmtu; + if (fib_lookup(dev_net(rt->dst.dev), fl4, &res) == 0) { + struct fib_nh *nh = &FIB_RES_NH(res); + struct fib_nh_exception *fnhe; + + spin_lock_bh(&fnhe_lock); + fnhe = find_or_create_fnhe(nh, fl4->daddr); + if (fnhe) { + fnhe->fnhe_pmtu = mtu; + fnhe->fnhe_expires = jiffies + ip_rt_mtu_expires; + } + spin_unlock_bh(&fnhe_lock); + } rt->rt_pmtu = mtu; dst_set_expires(&rt->dst, ip_rt_mtu_expires); } +static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk, + struct sk_buff *skb, u32 mtu) +{ + struct rtable *rt = (struct rtable *) dst; + struct flowi4 fl4; + + ip_rt_build_flow_key(&fl4, sk, skb); + __ip_rt_update_pmtu(rt, &fl4, mtu); +} + void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu, int oif, u32 mark, u8 protocol, int flow_flags) { - const struct iphdr *iph = (const struct iphdr *)skb->data; + const struct iphdr *iph = (const struct iphdr *) skb->data; struct flowi4 fl4; struct rtable *rt; - flowi4_init_output(&fl4, oif, mark, RT_TOS(iph->tos), RT_SCOPE_UNIVERSE, - protocol, flow_flags, - iph->daddr, iph->saddr, 0, 0); + __build_flow_key(&fl4, NULL, iph, oif, + RT_TOS(iph->tos), protocol, mark, flow_flags); rt = __ip_route_output_key(net, &fl4); if (!IS_ERR(rt)) { - ip_rt_update_pmtu(&rt->dst, NULL, skb, mtu); + __ip_rt_update_pmtu(rt, &fl4, mtu); ip_rt_put(rt); } } @@ -1542,27 +1696,31 @@ EXPORT_SYMBOL_GPL(ipv4_update_pmtu); void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu) { - const struct inet_sock *inet = inet_sk(sk); + const struct iphdr *iph = (const struct iphdr *) skb->data; + struct flowi4 fl4; + struct rtable *rt; - return ipv4_update_pmtu(skb, sock_net(sk), mtu, - sk->sk_bound_dev_if, sk->sk_mark, - inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol, - inet_sk_flowi_flags(sk)); + __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0); + rt = __ip_route_output_key(sock_net(sk), &fl4); + if (!IS_ERR(rt)) { + __ip_rt_update_pmtu(rt, &fl4, mtu); + ip_rt_put(rt); + } } EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu); void ipv4_redirect(struct sk_buff *skb, struct net *net, int oif, u32 mark, u8 protocol, int flow_flags) { - const struct iphdr *iph = (const struct iphdr *)skb->data; + const struct iphdr *iph = (const struct iphdr *) skb->data; struct flowi4 fl4; struct rtable *rt; - flowi4_init_output(&fl4, oif, mark, RT_TOS(iph->tos), RT_SCOPE_UNIVERSE, - protocol, flow_flags, iph->daddr, iph->saddr, 0, 0); + __build_flow_key(&fl4, NULL, iph, oif, + RT_TOS(iph->tos), protocol, mark, flow_flags); rt = __ip_route_output_key(net, &fl4); if (!IS_ERR(rt)) { - ip_do_redirect(&rt->dst, NULL, skb); + __ip_do_redirect(rt, skb, &fl4); ip_rt_put(rt); } } @@ -1570,12 +1728,16 @@ EXPORT_SYMBOL_GPL(ipv4_redirect); void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk) { - const struct inet_sock *inet = inet_sk(sk); + const struct iphdr *iph = (const struct iphdr *) skb->data; + struct flowi4 fl4; + struct rtable *rt; - return ipv4_redirect(skb, sock_net(sk), sk->sk_bound_dev_if, - sk->sk_mark, - inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol, - inet_sk_flowi_flags(sk)); + __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0); + rt = __ip_route_output_key(sock_net(sk), &fl4); + if (!IS_ERR(rt)) { + __ip_do_redirect(rt, skb, &fl4); + ip_rt_put(rt); + } } EXPORT_SYMBOL_GPL(ipv4_sk_redirect); @@ -1722,14 +1884,46 @@ static void rt_init_metrics(struct rtable *rt, const struct flowi4 *fl4, dst_init_metrics(&rt->dst, fi->fib_metrics, true); } +static void rt_bind_exception(struct rtable *rt, struct fib_nh *nh, __be32 daddr) +{ + struct fnhe_hash_bucket *hash = nh->nh_exceptions; + struct fib_nh_exception *fnhe; + u32 hval; + + hval = (__force u32) daddr; + hval ^= (hval >> 11) ^ (hval >> 22); + + for (fnhe = rcu_dereference(hash[hval].chain); fnhe; + fnhe = rcu_dereference(fnhe->fnhe_next)) { + if (fnhe->fnhe_daddr == daddr) { + if (fnhe->fnhe_pmtu) { + unsigned long expires = fnhe->fnhe_expires; + unsigned long diff = jiffies - expires; + + if (time_before(jiffies, expires)) { + rt->rt_pmtu = fnhe->fnhe_pmtu; + dst_set_expires(&rt->dst, diff); + } + } + if (fnhe->fnhe_gw) + rt->rt_gateway = fnhe->fnhe_gw; + fnhe->fnhe_stamp = jiffies; + break; + } + } +} + static void rt_set_nexthop(struct rtable *rt, const struct flowi4 *fl4, const struct fib_result *res, struct fib_info *fi, u16 type, u32 itag) { if (fi) { - if (FIB_RES_GW(*res) && - FIB_RES_NH(*res).nh_scope == RT_SCOPE_LINK) - rt->rt_gateway = FIB_RES_GW(*res); + struct fib_nh *nh = &FIB_RES_NH(*res); + + if (nh->nh_gw && nh->nh_scope == RT_SCOPE_LINK) + rt->rt_gateway = nh->nh_gw; + if (unlikely(nh->nh_exceptions)) + rt_bind_exception(rt, nh, fl4->daddr); rt_init_metrics(rt, fl4, fi); #ifdef CONFIG_IP_ROUTE_CLASSID rt->dst.tclassid = FIB_RES_NH(*res).nh_tclassid;