From 9ab179d83b4e31ea277a123492e419067c2f129a Mon Sep 17 00:00:00 2001 From: David Ahern Date: Thu, 7 Apr 2016 11:10:06 -0700 Subject: [PATCH] net: vrf: Fix dst reference counting Vivek reported a kernel exception deleting a VRF with an active connection through it. The root cause is that the socket has a cached reference to a dst that is destroyed. Converting the dst_destroy to dst_release and letting proper reference counting kick in does not work as the dst has a reference to the device which needs to be released as well. I talked to Hannes about this at netdev and he pointed out the ipv4 and ipv6 dst handling has dst_ifdown for just this scenario. Rather than continuing with the reinvented dst wheel in VRF just remove it and leverage the ipv4 and ipv6 versions. Fixes: 193125dbd8eb2 ("net: Introduce VRF device driver") Fixes: 35402e3136634 ("net: Add IPv6 support to VRF device") Signed-off-by: David Ahern Signed-off-by: David S. Miller --- drivers/net/vrf.c | 177 +++++------------------------------------------- include/net/ip6_route.h | 3 + include/net/route.h | 3 + net/ipv4/route.c | 7 +- net/ipv6/route.c | 7 +- 5 files changed, 30 insertions(+), 167 deletions(-) diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c index 9a9fabb..8a8f1e5 100644 --- a/drivers/net/vrf.c +++ b/drivers/net/vrf.c @@ -60,41 +60,6 @@ struct pcpu_dstats { struct u64_stats_sync syncp; }; -static struct dst_entry *vrf_ip_check(struct dst_entry *dst, u32 cookie) -{ - return dst; -} - -static int vrf_ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb) -{ - return ip_local_out(net, sk, skb); -} - -static unsigned int vrf_v4_mtu(const struct dst_entry *dst) -{ - /* TO-DO: return max ethernet size? */ - return dst->dev->mtu; -} - -static void vrf_dst_destroy(struct dst_entry *dst) -{ - /* our dst lives forever - or until the device is closed */ -} - -static unsigned int vrf_default_advmss(const struct dst_entry *dst) -{ - return 65535 - 40; -} - -static struct dst_ops vrf_dst_ops = { - .family = AF_INET, - .local_out = vrf_ip_local_out, - .check = vrf_ip_check, - .mtu = vrf_v4_mtu, - .destroy = vrf_dst_destroy, - .default_advmss = vrf_default_advmss, -}; - /* neighbor handling is done with actual device; do not want * to flip skb->dev for those ndisc packets. This really fails * for multiple next protocols (e.g., NEXTHDR_HOP). But it is @@ -349,46 +314,6 @@ static netdev_tx_t vrf_xmit(struct sk_buff *skb, struct net_device *dev) } #if IS_ENABLED(CONFIG_IPV6) -static struct dst_entry *vrf_ip6_check(struct dst_entry *dst, u32 cookie) -{ - return dst; -} - -static struct dst_ops vrf_dst_ops6 = { - .family = AF_INET6, - .local_out = ip6_local_out, - .check = vrf_ip6_check, - .mtu = vrf_v4_mtu, - .destroy = vrf_dst_destroy, - .default_advmss = vrf_default_advmss, -}; - -static int init_dst_ops6_kmem_cachep(void) -{ - vrf_dst_ops6.kmem_cachep = kmem_cache_create("vrf_ip6_dst_cache", - sizeof(struct rt6_info), - 0, - SLAB_HWCACHE_ALIGN, - NULL); - - if (!vrf_dst_ops6.kmem_cachep) - return -ENOMEM; - - return 0; -} - -static void free_dst_ops6_kmem_cachep(void) -{ - kmem_cache_destroy(vrf_dst_ops6.kmem_cachep); -} - -static int vrf_input6(struct sk_buff *skb) -{ - skb->dev->stats.rx_errors++; - kfree_skb(skb); - return 0; -} - /* modelled after ip6_finish_output2 */ static int vrf_finish_output6(struct net *net, struct sock *sk, struct sk_buff *skb) @@ -429,67 +354,34 @@ static int vrf_output6(struct net *net, struct sock *sk, struct sk_buff *skb) !(IP6CB(skb)->flags & IP6SKB_REROUTED)); } -static void vrf_rt6_destroy(struct net_vrf *vrf) +static void vrf_rt6_release(struct net_vrf *vrf) { - dst_destroy(&vrf->rt6->dst); - free_percpu(vrf->rt6->rt6i_pcpu); + dst_release(&vrf->rt6->dst); vrf->rt6 = NULL; } static int vrf_rt6_create(struct net_device *dev) { struct net_vrf *vrf = netdev_priv(dev); - struct dst_entry *dst; + struct net *net = dev_net(dev); struct rt6_info *rt6; - int cpu; int rc = -ENOMEM; - rt6 = dst_alloc(&vrf_dst_ops6, dev, 0, - DST_OBSOLETE_NONE, - (DST_HOST | DST_NOPOLICY | DST_NOXFRM)); + rt6 = ip6_dst_alloc(net, dev, + DST_HOST | DST_NOPOLICY | DST_NOXFRM | DST_NOCACHE); if (!rt6) goto out; - dst = &rt6->dst; - - rt6->rt6i_pcpu = alloc_percpu_gfp(struct rt6_info *, GFP_KERNEL); - if (!rt6->rt6i_pcpu) { - dst_destroy(dst); - goto out; - } - for_each_possible_cpu(cpu) { - struct rt6_info **p = per_cpu_ptr(rt6->rt6i_pcpu, cpu); - *p = NULL; - } - - memset(dst + 1, 0, sizeof(*rt6) - sizeof(*dst)); - - INIT_LIST_HEAD(&rt6->rt6i_siblings); - INIT_LIST_HEAD(&rt6->rt6i_uncached); - - rt6->dst.input = vrf_input6; rt6->dst.output = vrf_output6; - - rt6->rt6i_table = fib6_get_table(dev_net(dev), vrf->tb_id); - - atomic_set(&rt6->dst.__refcnt, 2); - + rt6->rt6i_table = fib6_get_table(net, vrf->tb_id); + dst_hold(&rt6->dst); vrf->rt6 = rt6; rc = 0; out: return rc; } #else -static int init_dst_ops6_kmem_cachep(void) -{ - return 0; -} - -static void free_dst_ops6_kmem_cachep(void) -{ -} - -static void vrf_rt6_destroy(struct net_vrf *vrf) +static void vrf_rt6_release(struct net_vrf *vrf) { } @@ -557,11 +449,11 @@ static int vrf_output(struct net *net, struct sock *sk, struct sk_buff *skb) !(IPCB(skb)->flags & IPSKB_REROUTED)); } -static void vrf_rtable_destroy(struct net_vrf *vrf) +static void vrf_rtable_release(struct net_vrf *vrf) { struct dst_entry *dst = (struct dst_entry *)vrf->rth; - dst_destroy(dst); + dst_release(dst); vrf->rth = NULL; } @@ -570,22 +462,10 @@ static struct rtable *vrf_rtable_create(struct net_device *dev) struct net_vrf *vrf = netdev_priv(dev); struct rtable *rth; - rth = dst_alloc(&vrf_dst_ops, dev, 2, - DST_OBSOLETE_NONE, - (DST_HOST | DST_NOPOLICY | DST_NOXFRM)); + rth = rt_dst_alloc(dev, 0, RTN_UNICAST, 1, 1, 0); if (rth) { rth->dst.output = vrf_output; - rth->rt_genid = rt_genid_ipv4(dev_net(dev)); - rth->rt_flags = 0; - rth->rt_type = RTN_UNICAST; - rth->rt_is_input = 0; - rth->rt_iif = 0; - rth->rt_pmtu = 0; - rth->rt_gateway = 0; - rth->rt_uses_gateway = 0; rth->rt_table_id = vrf->tb_id; - INIT_LIST_HEAD(&rth->rt_uncached); - rth->rt_uncached_list = NULL; } return rth; @@ -673,8 +553,8 @@ static void vrf_dev_uninit(struct net_device *dev) struct net_device *port_dev; struct list_head *iter; - vrf_rtable_destroy(vrf); - vrf_rt6_destroy(vrf); + vrf_rtable_release(vrf); + vrf_rt6_release(vrf); netdev_for_each_lower_dev(dev, port_dev, iter) vrf_del_slave(dev, port_dev); @@ -704,7 +584,7 @@ static int vrf_dev_init(struct net_device *dev) return 0; out_rth: - vrf_rtable_destroy(vrf); + vrf_rtable_release(vrf); out_stats: free_percpu(dev->dstats); dev->dstats = NULL; @@ -737,7 +617,7 @@ static struct rtable *vrf_get_rtable(const struct net_device *dev, struct net_vrf *vrf = netdev_priv(dev); rth = vrf->rth; - atomic_inc(&rth->dst.__refcnt); + dst_hold(&rth->dst); } return rth; @@ -788,7 +668,7 @@ static struct dst_entry *vrf_get_rt6_dst(const struct net_device *dev, struct net_vrf *vrf = netdev_priv(dev); rt = vrf->rt6; - atomic_inc(&rt->dst.__refcnt); + dst_hold(&rt->dst); } return (struct dst_entry *)rt; @@ -946,19 +826,6 @@ static int __init vrf_init_module(void) { int rc; - vrf_dst_ops.kmem_cachep = - kmem_cache_create("vrf_ip_dst_cache", - sizeof(struct rtable), 0, - SLAB_HWCACHE_ALIGN, - NULL); - - if (!vrf_dst_ops.kmem_cachep) - return -ENOMEM; - - rc = init_dst_ops6_kmem_cachep(); - if (rc != 0) - goto error2; - register_netdevice_notifier(&vrf_notifier_block); rc = rtnl_link_register(&vrf_link_ops); @@ -969,22 +836,10 @@ static int __init vrf_init_module(void) error: unregister_netdevice_notifier(&vrf_notifier_block); - free_dst_ops6_kmem_cachep(); -error2: - kmem_cache_destroy(vrf_dst_ops.kmem_cachep); return rc; } -static void __exit vrf_cleanup_module(void) -{ - rtnl_link_unregister(&vrf_link_ops); - unregister_netdevice_notifier(&vrf_notifier_block); - kmem_cache_destroy(vrf_dst_ops.kmem_cachep); - free_dst_ops6_kmem_cachep(); -} - module_init(vrf_init_module); -module_exit(vrf_cleanup_module); MODULE_AUTHOR("Shrijeet Mukherjee, David Ahern"); MODULE_DESCRIPTION("Device driver to instantiate VRF domains"); MODULE_LICENSE("GPL"); diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h index 295d291..54c7794 100644 --- a/include/net/ip6_route.h +++ b/include/net/ip6_route.h @@ -101,6 +101,9 @@ void fib6_force_start_gc(struct net *net); struct rt6_info *addrconf_dst_alloc(struct inet6_dev *idev, const struct in6_addr *addr, bool anycast); +struct rt6_info *ip6_dst_alloc(struct net *net, struct net_device *dev, + int flags); + /* * support functions for ND * diff --git a/include/net/route.h b/include/net/route.h index 9b0a523..6de665b 100644 --- a/include/net/route.h +++ b/include/net/route.h @@ -209,6 +209,9 @@ unsigned int inet_addr_type_dev_table(struct net *net, void ip_rt_multicast_event(struct in_device *); int ip_rt_ioctl(struct net *, unsigned int cmd, void __user *arg); void ip_rt_get_source(u8 *src, struct sk_buff *skb, struct rtable *rt); +struct rtable *rt_dst_alloc(struct net_device *dev, + unsigned int flags, u16 type, + bool nopolicy, bool noxfrm, bool will_cache); struct in_ifaddr; void fib_add_ifaddr(struct in_ifaddr *); diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 02c6229..2852bdf 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1438,9 +1438,9 @@ static void rt_set_nexthop(struct rtable *rt, __be32 daddr, #endif } -static struct rtable *rt_dst_alloc(struct net_device *dev, - unsigned int flags, u16 type, - bool nopolicy, bool noxfrm, bool will_cache) +struct rtable *rt_dst_alloc(struct net_device *dev, + unsigned int flags, u16 type, + bool nopolicy, bool noxfrm, bool will_cache) { struct rtable *rt; @@ -1468,6 +1468,7 @@ static struct rtable *rt_dst_alloc(struct net_device *dev, return rt; } +EXPORT_SYMBOL(rt_dst_alloc); /* called in rcu_read_lock() section */ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr, diff --git a/net/ipv6/route.c b/net/ipv6/route.c index ed44663..1d8871a 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -338,9 +338,9 @@ static struct rt6_info *__ip6_dst_alloc(struct net *net, return rt; } -static struct rt6_info *ip6_dst_alloc(struct net *net, - struct net_device *dev, - int flags) +struct rt6_info *ip6_dst_alloc(struct net *net, + struct net_device *dev, + int flags) { struct rt6_info *rt = __ip6_dst_alloc(net, dev, flags); @@ -364,6 +364,7 @@ static struct rt6_info *ip6_dst_alloc(struct net *net, return rt; } +EXPORT_SYMBOL(ip6_dst_alloc); static void ip6_dst_destroy(struct dst_entry *dst) { -- 2.7.4