From 8405a8fff3f8545c888a872d6e3c0c8eecd4d348 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 19 Jun 2015 14:03:39 -0500 Subject: [PATCH] netfilter: nf_qeueue: Drop queue entries on nf_unregister_hook Add code to nf_unregister_hook to flush the nf_queue when a hook is unregistered. This guarantees that the pointer that the nf_queue code retains into the nf_hook list will remain valid while a packet is queued. I tested what would happen if we do not flush queued packets and was trivially able to obtain the oops below. All that was required was to stop the nf_queue listening process, to delete all of the nf_tables, and to awaken the nf_queue listening process. > BUG: unable to handle kernel paging request at 0000000100000001 > IP: [<0000000100000001>] 0x100000001 > PGD b9c35067 PUD 0 > Oops: 0010 [#1] SMP > Modules linked in: > CPU: 0 PID: 519 Comm: lt-nfqnl_test Not tainted > task: ffff8800b9c8c050 ti: ffff8800ba9d8000 task.ti: ffff8800ba9d8000 > RIP: 0010:[<0000000100000001>] [<0000000100000001>] 0x100000001 > RSP: 0018:ffff8800ba9dba40 EFLAGS: 00010a16 > RAX: ffff8800bab48a00 RBX: ffff8800ba9dba90 RCX: ffff8800ba9dba90 > RDX: ffff8800b9c10128 RSI: ffff8800ba940900 RDI: ffff8800bab48a00 > RBP: ffff8800b9c10128 R08: ffffffff82976660 R09: ffff8800ba9dbb28 > R10: dead000000100100 R11: dead000000200200 R12: ffff8800ba940900 > R13: ffffffff8313fd50 R14: ffff8800b9c95200 R15: 0000000000000000 > FS: 00007fb91fc34700(0000) GS:ffff8800bfa00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000100000001 CR3: 00000000babfb000 CR4: 00000000000007f0 > Stack: > ffffffff8206ab0f ffffffff82982240 ffff8800bab48a00 ffff8800b9c100a8 > ffff8800b9c10100 0000000000000001 ffff8800ba940900 ffff8800b9c10128 > ffffffff8206bd65 ffff8800bfb0d5e0 ffff8800bab48a00 0000000000014dc0 > Call Trace: > [] ? nf_iterate+0x4f/0xa0 > [] ? nf_reinject+0x125/0x190 > [] ? nfqnl_recv_verdict+0x255/0x360 > [] ? nla_parse+0x80/0xf0 > [] ? nfnetlink_rcv_msg+0x13c/0x240 > [] ? __memcg_kmem_get_cache+0x4c/0x150 > [] ? nfnl_lock+0x20/0x20 > [] ? netlink_rcv_skb+0xa9/0xc0 > [] ? netlink_unicast+0x12f/0x1c0 > [] ? netlink_sendmsg+0x28e/0x650 > [] ? sock_sendmsg+0x44/0x50 > [] ? ___sys_sendmsg+0x2ab/0x2c0 > [] ? __wake_up+0x43/0x70 > [] ? tty_write+0x1c4/0x2a0 > [] ? __sys_sendmsg+0x44/0x80 > [] ? system_call_fastpath+0x12/0x6a > Code: Bad RIP value. > RIP [<0000000100000001>] 0x100000001 > RSP > CR2: 0000000100000001 > ---[ end trace 08eb65d42362793f ]--- Cc: stable@vger.kernel.org Signed-off-by: "Eric W. Biederman" Signed-off-by: David S. Miller --- include/net/netfilter/nf_queue.h | 2 ++ net/netfilter/core.c | 1 + net/netfilter/nf_internals.h | 1 + net/netfilter/nf_queue.c | 17 +++++++++++++++++ net/netfilter/nfnetlink_queue_core.c | 24 +++++++++++++++++++++++- 5 files changed, 44 insertions(+), 1 deletion(-) diff --git a/include/net/netfilter/nf_queue.h b/include/net/netfilter/nf_queue.h index d81d584157e1..e8635854a55b 100644 --- a/include/net/netfilter/nf_queue.h +++ b/include/net/netfilter/nf_queue.h @@ -24,6 +24,8 @@ struct nf_queue_entry { struct nf_queue_handler { int (*outfn)(struct nf_queue_entry *entry, unsigned int queuenum); + void (*nf_hook_drop)(struct net *net, + struct nf_hook_ops *ops); }; void nf_register_queue_handler(const struct nf_queue_handler *qh); diff --git a/net/netfilter/core.c b/net/netfilter/core.c index 653e32eac08c..a0e54974e2c9 100644 --- a/net/netfilter/core.c +++ b/net/netfilter/core.c @@ -118,6 +118,7 @@ void nf_unregister_hook(struct nf_hook_ops *reg) static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]); #endif synchronize_net(); + nf_queue_nf_hook_drop(reg); } EXPORT_SYMBOL(nf_unregister_hook); diff --git a/net/netfilter/nf_internals.h b/net/netfilter/nf_internals.h index ea7f36784b3d..399210693c2a 100644 --- a/net/netfilter/nf_internals.h +++ b/net/netfilter/nf_internals.h @@ -19,6 +19,7 @@ unsigned int nf_iterate(struct list_head *head, struct sk_buff *skb, /* nf_queue.c */ int nf_queue(struct sk_buff *skb, struct nf_hook_ops *elem, struct nf_hook_state *state, unsigned int queuenum); +void nf_queue_nf_hook_drop(struct nf_hook_ops *ops); int __init netfilter_queue_init(void); /* nf_log.c */ diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c index 2e88032cd5ad..cd60d397fe05 100644 --- a/net/netfilter/nf_queue.c +++ b/net/netfilter/nf_queue.c @@ -105,6 +105,23 @@ bool nf_queue_entry_get_refs(struct nf_queue_entry *entry) } EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs); +void nf_queue_nf_hook_drop(struct nf_hook_ops *ops) +{ + const struct nf_queue_handler *qh; + struct net *net; + + rtnl_lock(); + rcu_read_lock(); + qh = rcu_dereference(queue_handler); + if (qh) { + for_each_net(net) { + qh->nf_hook_drop(net, ops); + } + } + rcu_read_unlock(); + rtnl_unlock(); +} + /* * Any packet that leaves via this function must come back * through nf_reinject(). diff --git a/net/netfilter/nfnetlink_queue_core.c b/net/netfilter/nfnetlink_queue_core.c index e26a46ef19ba..685cc6a17163 100644 --- a/net/netfilter/nfnetlink_queue_core.c +++ b/net/netfilter/nfnetlink_queue_core.c @@ -850,6 +850,27 @@ static struct notifier_block nfqnl_dev_notifier = { .notifier_call = nfqnl_rcv_dev_event, }; +static int nf_hook_cmp(struct nf_queue_entry *entry, unsigned long ops_ptr) +{ + return entry->elem == (struct nf_hook_ops *)ops_ptr; +} + +static void nfqnl_nf_hook_drop(struct net *net, struct nf_hook_ops *hook) +{ + struct nfnl_queue_net *q = nfnl_queue_pernet(net); + int i; + + rcu_read_lock(); + for (i = 0; i < INSTANCE_BUCKETS; i++) { + struct nfqnl_instance *inst; + struct hlist_head *head = &q->instance_table[i]; + + hlist_for_each_entry_rcu(inst, head, hlist) + nfqnl_flush(inst, nf_hook_cmp, (unsigned long)hook); + } + rcu_read_unlock(); +} + static int nfqnl_rcv_nl_event(struct notifier_block *this, unsigned long event, void *ptr) @@ -1057,7 +1078,8 @@ static const struct nla_policy nfqa_cfg_policy[NFQA_CFG_MAX+1] = { }; static const struct nf_queue_handler nfqh = { - .outfn = &nfqnl_enqueue_packet, + .outfn = &nfqnl_enqueue_packet, + .nf_hook_drop = &nfqnl_nf_hook_drop, }; static int -- 2.30.2