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: > [<ffffffff8206ab0f>] ? nf_iterate+0x4f/0xa0 > [<ffffffff8206bd65>] ? nf_reinject+0x125/0x190 > [<ffffffff8206dee5>] ? nfqnl_recv_verdict+0x255/0x360 > [<ffffffff81386290>] ? nla_parse+0x80/0xf0 > [<ffffffff8206c42c>] ? nfnetlink_rcv_msg+0x13c/0x240 > [<ffffffff811b2fec>] ? __memcg_kmem_get_cache+0x4c/0x150 > [<ffffffff8206c2f0>] ? nfnl_lock+0x20/0x20 > [<ffffffff82068159>] ? netlink_rcv_skb+0xa9/0xc0 > [<ffffffff820677bf>] ? netlink_unicast+0x12f/0x1c0 > [<ffffffff82067ade>] ? netlink_sendmsg+0x28e/0x650 > [<ffffffff81fdd814>] ? sock_sendmsg+0x44/0x50 > [<ffffffff81fde07b>] ? ___sys_sendmsg+0x2ab/0x2c0 > [<ffffffff810e8f73>] ? __wake_up+0x43/0x70 > [<ffffffff8141a134>] ? tty_write+0x1c4/0x2a0 > [<ffffffff81fde9f4>] ? __sys_sendmsg+0x44/0x80 > [<ffffffff823ff8d7>] ? system_call_fastpath+0x12/0x6a > Code: Bad RIP value. > RIP [<0000000100000001>] 0x100000001 > RSP <ffff8800ba9dba40> > CR2: 0000000100000001 > ---[ end trace 08eb65d42362793f ]--- Cc: stable@vger.kernel.org Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -24,6 +24,8 @@ struct nf_queue_entry {
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struct nf_queue_handler {
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int (*outfn)(struct nf_queue_entry *entry,
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unsigned int queuenum);
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void (*nf_hook_drop)(struct net *net,
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struct nf_hook_ops *ops);
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};
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void nf_register_queue_handler(const struct nf_queue_handler *qh);
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@ -118,6 +118,7 @@ void nf_unregister_hook(struct nf_hook_ops *reg)
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static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
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#endif
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synchronize_net();
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nf_queue_nf_hook_drop(reg);
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}
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EXPORT_SYMBOL(nf_unregister_hook);
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@ -19,6 +19,7 @@ unsigned int nf_iterate(struct list_head *head, struct sk_buff *skb,
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/* nf_queue.c */
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int nf_queue(struct sk_buff *skb, struct nf_hook_ops *elem,
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struct nf_hook_state *state, unsigned int queuenum);
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void nf_queue_nf_hook_drop(struct nf_hook_ops *ops);
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int __init netfilter_queue_init(void);
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/* nf_log.c */
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@ -105,6 +105,23 @@ bool nf_queue_entry_get_refs(struct nf_queue_entry *entry)
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}
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EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs);
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void nf_queue_nf_hook_drop(struct nf_hook_ops *ops)
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{
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const struct nf_queue_handler *qh;
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struct net *net;
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rtnl_lock();
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rcu_read_lock();
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qh = rcu_dereference(queue_handler);
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if (qh) {
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for_each_net(net) {
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qh->nf_hook_drop(net, ops);
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}
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}
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rcu_read_unlock();
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rtnl_unlock();
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}
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/*
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* Any packet that leaves via this function must come back
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* through nf_reinject().
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@ -850,6 +850,27 @@ static struct notifier_block nfqnl_dev_notifier = {
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.notifier_call = nfqnl_rcv_dev_event,
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};
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static int nf_hook_cmp(struct nf_queue_entry *entry, unsigned long ops_ptr)
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{
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return entry->elem == (struct nf_hook_ops *)ops_ptr;
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}
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static void nfqnl_nf_hook_drop(struct net *net, struct nf_hook_ops *hook)
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{
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struct nfnl_queue_net *q = nfnl_queue_pernet(net);
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int i;
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rcu_read_lock();
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for (i = 0; i < INSTANCE_BUCKETS; i++) {
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struct nfqnl_instance *inst;
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struct hlist_head *head = &q->instance_table[i];
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hlist_for_each_entry_rcu(inst, head, hlist)
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nfqnl_flush(inst, nf_hook_cmp, (unsigned long)hook);
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}
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rcu_read_unlock();
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}
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static int
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nfqnl_rcv_nl_event(struct notifier_block *this,
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unsigned long event, void *ptr)
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@ -1057,7 +1078,8 @@ static const struct nla_policy nfqa_cfg_policy[NFQA_CFG_MAX+1] = {
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};
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static const struct nf_queue_handler nfqh = {
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.outfn = &nfqnl_enqueue_packet,
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.outfn = &nfqnl_enqueue_packet,
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.nf_hook_drop = &nfqnl_nf_hook_drop,
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};
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static int
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