From 14e50e57aedb2a89cf79b77782879769794cab7b Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Thu, 24 May 2007 18:17:54 -0700 Subject: [PATCH] [XFRM]: Allow packet drops during larval state resolution. The current IPSEC rule resolution behavior we have does not work for a lot of people, even though technically it's an improvement from the -EAGAIN buisness we had before. Right now we'll block until the key manager resolves the route. That works for simple cases, but many folks would rather packets get silently dropped until the key manager resolves the IPSEC rules. We can't tell these folks to "set the socket non-blocking" because they don't have control over the non-block setting of things like the sockets used to resolve DNS deep inside of the resolver libraries in libc. With that in mind I coded up the patch below with some help from Herbert Xu which provides packet-drop behavior during larval state resolution, controllable via sysctl and off by default. This lays the framework to either: 1) Make this default at some point or... 2) Move this logic into xfrm{4,6}_policy.c and implement the ARP-like resolution queue we've all been dreaming of. The idea would be to queue packets to the policy, then once the larval state is resolved by the key manager we re-resolve the route and push the packets out. The packets would timeout if the rule didn't get resolved in a certain amount of time. Signed-off-by: David S. Miller --- include/net/dst.h | 7 ++++ include/net/ipv6.h | 3 ++ net/core/sysctl_net_core.c | 9 +++++ net/dccp/ipv6.c | 10 ++++-- net/ipv4/route.c | 71 +++++++++++++++++++++++++++++++++++++- net/ipv6/datagram.c | 8 +++-- net/ipv6/raw.c | 8 +++-- net/ipv6/route.c | 63 +++++++++++++++++++++++++++++++++ net/ipv6/tcp_ipv6.c | 8 +++-- net/ipv6/udp.c | 8 +++-- net/xfrm/xfrm_policy.c | 28 +++++++++++++-- 11 files changed, 209 insertions(+), 14 deletions(-) diff --git a/include/net/dst.h b/include/net/dst.h index e12a8ce0b9b..82270f9332d 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -265,9 +265,16 @@ static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, { return 0; } +static inline int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, + struct sock *sk, int flags) +{ + return 0; +} #else extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, struct sock *sk, int flags); +extern int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, + struct sock *sk, int flags); #endif #endif diff --git a/include/net/ipv6.h b/include/net/ipv6.h index 4fa5dfe886c..78a0d06d98d 100644 --- a/include/net/ipv6.h +++ b/include/net/ipv6.h @@ -469,6 +469,9 @@ extern void ip6_flush_pending_frames(struct sock *sk); extern int ip6_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl); +extern int ip6_dst_blackhole(struct sock *sk, + struct dst_entry **dst, + struct flowi *fl); extern int ip6_sk_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl); diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index b29712033dd..f34aca041a2 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -24,6 +24,7 @@ extern int sysctl_core_destroy_delay; #ifdef CONFIG_XFRM extern u32 sysctl_xfrm_aevent_etime; extern u32 sysctl_xfrm_aevent_rseqth; +extern int sysctl_xfrm_larval_drop; #endif ctl_table core_table[] = { @@ -118,6 +119,14 @@ ctl_table core_table[] = { .mode = 0644, .proc_handler = &proc_dointvec }, + { + .ctl_name = CTL_UNNUMBERED, + .procname = "xfrm_larval_drop", + .data = &sysctl_xfrm_larval_drop, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = &proc_dointvec + }, #endif /* CONFIG_XFRM */ #endif /* CONFIG_NET */ { diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c index 64eac2515aa..31737cdf156 100644 --- a/net/dccp/ipv6.c +++ b/net/dccp/ipv6.c @@ -1043,9 +1043,13 @@ static int dccp_v6_connect(struct sock *sk, struct sockaddr *uaddr, if (final_p) ipv6_addr_copy(&fl.fl6_dst, final_p); - err = xfrm_lookup(&dst, &fl, sk, 1); - if (err < 0) - goto failure; + err = __xfrm_lookup(&dst, &fl, sk, 1); + if (err < 0) { + if (err == -EREMOTE) + err = ip6_dst_blackhole(sk, &dst, &fl); + if (err < 0) + goto failure; + } if (saddr == NULL) { saddr = &fl.fl6_src; diff --git a/net/ipv4/route.c b/net/ipv4/route.c index df9fe4f2e8c..8603cfb271f 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -2598,6 +2598,69 @@ int __ip_route_output_key(struct rtable **rp, const struct flowi *flp) EXPORT_SYMBOL_GPL(__ip_route_output_key); +static void ipv4_rt_blackhole_update_pmtu(struct dst_entry *dst, u32 mtu) +{ +} + +static struct dst_ops ipv4_dst_blackhole_ops = { + .family = AF_INET, + .protocol = __constant_htons(ETH_P_IP), + .destroy = ipv4_dst_destroy, + .check = ipv4_dst_check, + .update_pmtu = ipv4_rt_blackhole_update_pmtu, + .entry_size = sizeof(struct rtable), +}; + + +static int ipv4_blackhole_output(struct sk_buff *skb) +{ + kfree_skb(skb); + return 0; +} + +static int ipv4_dst_blackhole(struct rtable **rp, struct flowi *flp, struct sock *sk) +{ + struct rtable *ort = *rp; + struct rtable *rt = (struct rtable *) + dst_alloc(&ipv4_dst_blackhole_ops); + + if (rt) { + struct dst_entry *new = &rt->u.dst; + + atomic_set(&new->__refcnt, 1); + new->__use = 1; + new->input = ipv4_blackhole_output; + new->output = ipv4_blackhole_output; + memcpy(new->metrics, ort->u.dst.metrics, RTAX_MAX*sizeof(u32)); + + new->dev = ort->u.dst.dev; + if (new->dev) + dev_hold(new->dev); + + rt->fl = ort->fl; + + rt->idev = ort->idev; + if (rt->idev) + in_dev_hold(rt->idev); + rt->rt_flags = ort->rt_flags; + rt->rt_type = ort->rt_type; + rt->rt_dst = ort->rt_dst; + rt->rt_src = ort->rt_src; + rt->rt_iif = ort->rt_iif; + rt->rt_gateway = ort->rt_gateway; + rt->rt_spec_dst = ort->rt_spec_dst; + rt->peer = ort->peer; + if (rt->peer) + atomic_inc(&rt->peer->refcnt); + + dst_free(new); + } + + dst_release(&(*rp)->u.dst); + *rp = rt; + return (rt ? 0 : -ENOMEM); +} + int ip_route_output_flow(struct rtable **rp, struct flowi *flp, struct sock *sk, int flags) { int err; @@ -2610,7 +2673,11 @@ int ip_route_output_flow(struct rtable **rp, struct flowi *flp, struct sock *sk, flp->fl4_src = (*rp)->rt_src; if (!flp->fl4_dst) flp->fl4_dst = (*rp)->rt_dst; - return xfrm_lookup((struct dst_entry **)rp, flp, sk, flags); + err = __xfrm_lookup((struct dst_entry **)rp, flp, sk, flags); + if (err == -EREMOTE) + err = ipv4_dst_blackhole(rp, flp, sk); + + return err; } return 0; @@ -3139,6 +3206,8 @@ int __init ip_rt_init(void) kmem_cache_create("ip_dst_cache", sizeof(struct rtable), 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); + ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep; + rt_hash_table = (struct rt_hash_bucket *) alloc_large_system_hash("IP route cache", sizeof(struct rt_hash_bucket), diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c index 403eee66b9c..b1fe7ac5dc9 100644 --- a/net/ipv6/datagram.c +++ b/net/ipv6/datagram.c @@ -177,8 +177,12 @@ ipv4_connected: if (final_p) ipv6_addr_copy(&fl.fl6_dst, final_p); - if ((err = xfrm_lookup(&dst, &fl, sk, 1)) < 0) - goto out; + if ((err = __xfrm_lookup(&dst, &fl, sk, 1)) < 0) { + if (err == -EREMOTE) + err = ip6_dst_blackhole(sk, &dst, &fl); + if (err < 0) + goto out; + } /* source address lookup done in ip6_dst_lookup */ diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c index 009a1047fc3..a58459a7668 100644 --- a/net/ipv6/raw.c +++ b/net/ipv6/raw.c @@ -818,8 +818,12 @@ static int rawv6_sendmsg(struct kiocb *iocb, struct sock *sk, if (final_p) ipv6_addr_copy(&fl.fl6_dst, final_p); - if ((err = xfrm_lookup(&dst, &fl, sk, 1)) < 0) - goto out; + if ((err = __xfrm_lookup(&dst, &fl, sk, 1)) < 0) { + if (err == -EREMOTE) + err = ip6_dst_blackhole(sk, &dst, &fl); + if (err < 0) + goto out; + } if (hlimit < 0) { if (ipv6_addr_is_multicast(&fl.fl6_dst)) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index b46ad53044b..1324b06796c 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -119,6 +119,19 @@ static struct dst_ops ip6_dst_ops = { .entry_size = sizeof(struct rt6_info), }; +static void ip6_rt_blackhole_update_pmtu(struct dst_entry *dst, u32 mtu) +{ +} + +static struct dst_ops ip6_dst_blackhole_ops = { + .family = AF_INET6, + .protocol = __constant_htons(ETH_P_IPV6), + .destroy = ip6_dst_destroy, + .check = ip6_dst_check, + .update_pmtu = ip6_rt_blackhole_update_pmtu, + .entry_size = sizeof(struct rt6_info), +}; + struct rt6_info ip6_null_entry = { .u = { .dst = { @@ -833,6 +846,54 @@ struct dst_entry * ip6_route_output(struct sock *sk, struct flowi *fl) EXPORT_SYMBOL(ip6_route_output); +static int ip6_blackhole_output(struct sk_buff *skb) +{ + kfree_skb(skb); + return 0; +} + +int ip6_dst_blackhole(struct sock *sk, struct dst_entry **dstp, struct flowi *fl) +{ + struct rt6_info *ort = (struct rt6_info *) *dstp; + struct rt6_info *rt = (struct rt6_info *) + dst_alloc(&ip6_dst_blackhole_ops); + struct dst_entry *new = NULL; + + if (rt) { + new = &rt->u.dst; + + atomic_set(&new->__refcnt, 1); + new->__use = 1; + new->input = ip6_blackhole_output; + new->output = ip6_blackhole_output; + + memcpy(new->metrics, ort->u.dst.metrics, RTAX_MAX*sizeof(u32)); + new->dev = ort->u.dst.dev; + if (new->dev) + dev_hold(new->dev); + rt->rt6i_idev = ort->rt6i_idev; + if (rt->rt6i_idev) + in6_dev_hold(rt->rt6i_idev); + rt->rt6i_expires = 0; + + ipv6_addr_copy(&rt->rt6i_gateway, &ort->rt6i_gateway); + rt->rt6i_flags = ort->rt6i_flags & ~RTF_EXPIRES; + rt->rt6i_metric = 0; + + memcpy(&rt->rt6i_dst, &ort->rt6i_dst, sizeof(struct rt6key)); +#ifdef CONFIG_IPV6_SUBTREES + memcpy(&rt->rt6i_src, &ort->rt6i_src, sizeof(struct rt6key)); +#endif + + dst_free(new); + } + + dst_release(*dstp); + *dstp = new; + return (new ? 0 : -ENOMEM); +} +EXPORT_SYMBOL_GPL(ip6_dst_blackhole); + /* * Destination cache support functions */ @@ -2495,6 +2556,8 @@ void __init ip6_route_init(void) ip6_dst_ops.kmem_cachep = kmem_cache_create("ip6_dst_cache", sizeof(struct rt6_info), 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); + ip6_dst_blackhole_ops.kmem_cachep = ip6_dst_ops.kmem_cachep; + fib6_init(); #ifdef CONFIG_PROC_FS p = proc_net_create("ipv6_route", 0, rt6_proc_info); diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index e2f25ea43b6..4f06a51ad4f 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -265,8 +265,12 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr, if (final_p) ipv6_addr_copy(&fl.fl6_dst, final_p); - if ((err = xfrm_lookup(&dst, &fl, sk, 1)) < 0) - goto failure; + if ((err = __xfrm_lookup(&dst, &fl, sk, 1)) < 0) { + if (err == -EREMOTE) + err = ip6_dst_blackhole(sk, &dst, &fl); + if (err < 0) + goto failure; + } if (saddr == NULL) { saddr = &fl.fl6_src; diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index a7ae59c954d..d1fbddd172e 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -767,8 +767,12 @@ do_udp_sendmsg: if (final_p) ipv6_addr_copy(&fl.fl6_dst, final_p); - if ((err = xfrm_lookup(&dst, &fl, sk, 1)) < 0) - goto out; + if ((err = __xfrm_lookup(&dst, &fl, sk, 1)) < 0) { + if (err == -EREMOTE) + err = ip6_dst_blackhole(sk, &dst, &fl); + if (err < 0) + goto out; + } if (hlimit < 0) { if (ipv6_addr_is_multicast(&fl.fl6_dst)) diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index d0882e53b6f..b8bab89616a 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -29,6 +29,8 @@ #include "xfrm_hash.h" +int sysctl_xfrm_larval_drop; + DEFINE_MUTEX(xfrm_cfg_mutex); EXPORT_SYMBOL(xfrm_cfg_mutex); @@ -1390,8 +1392,8 @@ static int stale_bundle(struct dst_entry *dst); * At the moment we eat a raw IP route. Mostly to speed up lookups * on interfaces with disabled IPsec. */ -int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, - struct sock *sk, int flags) +int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, + struct sock *sk, int flags) { struct xfrm_policy *policy; struct xfrm_policy *pols[XFRM_POLICY_TYPE_MAX]; @@ -1509,6 +1511,13 @@ restart: if (unlikely(nx<0)) { err = nx; + if (err == -EAGAIN && sysctl_xfrm_larval_drop) { + /* EREMOTE tells the caller to generate + * a one-shot blackhole route. + */ + xfrm_pol_put(policy); + return -EREMOTE; + } if (err == -EAGAIN && flags) { DECLARE_WAITQUEUE(wait, current); @@ -1598,6 +1607,21 @@ error: *dst_p = NULL; return err; } +EXPORT_SYMBOL(__xfrm_lookup); + +int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, + struct sock *sk, int flags) +{ + int err = __xfrm_lookup(dst_p, fl, sk, flags); + + if (err == -EREMOTE) { + dst_release(*dst_p); + *dst_p = NULL; + err = -EAGAIN; + } + + return err; +} EXPORT_SYMBOL(xfrm_lookup); static inline int -- 2.41.1