[PATCH 4.1 090/202] netfilter: nf_qeueue: Drop queue entries on nf_unregister_hook

From: Greg Kroah-Hartman
Date: Sun Oct 18 2015 - 00:08:38 EST

4.1-stable review patch. If anyone has any objections, please let me know.

------------------

From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>

commit 8405a8fff3f8545c888a872d6e3c0c8eecd4d348 upstream.

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 ]---

Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
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(-)

--- 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);
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -89,6 +89,7 @@ void nf_unregister_hook(struct nf_hook_o
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);

--- a/net/netfilter/nf_internals.h
+++ b/net/netfilter/nf_internals.h
@@ -19,6 +19,7 @@ unsigned int nf_iterate(struct list_head
/* 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 */
--- a/net/netfilter/nf_queue.c
+++ b/net/netfilter/nf_queue.c
@@ -105,6 +105,23 @@ bool nf_queue_entry_get_refs(struct nf_q
}
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().
--- a/net/netfilter/nfnetlink_queue_core.c
+++ b/net/netfilter/nfnetlink_queue_core.c
@@ -824,6 +824,27 @@ static struct notifier_block nfqnl_dev_n
.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)
@@ -1031,7 +1052,8 @@ static const struct nla_policy nfqa_cfg_
};

static const struct nf_queue_handler nfqh = {
- .outfn = &nfqnl_enqueue_packet,
+ .outfn = &nfqnl_enqueue_packet,
+ .nf_hook_drop = &nfqnl_nf_hook_drop,
};

static int


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