diff options
author | Eric W. Biederman <ebiederm@xmission.com> | 2016-05-13 21:18:52 -0500 |
---|---|---|
committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2016-05-25 11:54:22 +0200 |
commit | dc3ee32e96d74dd6c80eed63af5065cb75899299 (patch) | |
tree | 36a1998e4e612a8583a6b596130825312afd1cc6 /net/netfilter | |
parent | 720b287d8382616a29524dd98264ac1e3a069e9f (diff) |
netfilter: nf_queue: Make the queue_handler pernet
Florian Weber reported:
> Under full load (unshare() in loop -> OOM conditions) we can
> get kernel panic:
>
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
> IP: [<ffffffff81476c85>] nfqnl_nf_hook_drop+0x35/0x70
> [..]
> task: ffff88012dfa3840 ti: ffff88012dffc000 task.ti: ffff88012dffc000
> RIP: 0010:[<ffffffff81476c85>] [<ffffffff81476c85>] nfqnl_nf_hook_drop+0x35/0x70
> RSP: 0000:ffff88012dfffd80 EFLAGS: 00010206
> RAX: 0000000000000008 RBX: ffffffff81add0c0 RCX: ffff88013fd80000
> [..]
> Call Trace:
> [<ffffffff81474d98>] nf_queue_nf_hook_drop+0x18/0x20
> [<ffffffff814738eb>] nf_unregister_net_hook+0xdb/0x150
> [<ffffffff8147398f>] netfilter_net_exit+0x2f/0x60
> [<ffffffff8141b088>] ops_exit_list.isra.4+0x38/0x60
> [<ffffffff8141b652>] setup_net+0xc2/0x120
> [<ffffffff8141bd09>] copy_net_ns+0x79/0x120
> [<ffffffff8106965b>] create_new_namespaces+0x11b/0x1e0
> [<ffffffff810698a7>] unshare_nsproxy_namespaces+0x57/0xa0
> [<ffffffff8104baa2>] SyS_unshare+0x1b2/0x340
> [<ffffffff81608276>] entry_SYSCALL_64_fastpath+0x1e/0xa8
> Code: 65 00 48 89 e5 41 56 41 55 41 54 53 83 e8 01 48 8b 97 70 12 00 00 48 98 49 89 f4 4c 8b 74 c2 18 4d 8d 6e 08 49 81 c6 88 00 00 00 <49> 8b 5d 00 48 85 db 74 1a 48 89 df 4c 89 e2 48 c7 c6 90 68 47
>
The simple fix for this requires a new pernet variable for struct
nf_queue that indicates when it is safe to use the dynamically
allocated nf_queue state.
As we need a variable anyway make nf_register_queue_handler and
nf_unregister_queue_handler pernet. This allows the existing logic of
when it is safe to use the state from the nfnetlink_queue module to be
reused with no changes except for making it per net.
The syncrhonize_rcu from nf_unregister_queue_handler is moved to a new
function nfnl_queue_net_exit_batch so that the worst case of having a
syncrhonize_rcu in the pernet exit path is not experienced in batch
mode.
Reported-by: Florian Westphal <fw@strlen.de>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/netfilter')
-rw-r--r-- | net/netfilter/nf_queue.c | 17 | ||||
-rw-r--r-- | net/netfilter/nfnetlink_queue.c | 18 |
2 files changed, 20 insertions, 15 deletions
diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c index 5baa8e24e6ac..b19ad20a705c 100644 --- a/net/netfilter/nf_queue.c +++ b/net/netfilter/nf_queue.c @@ -26,23 +26,21 @@ * Once the queue is registered it must reinject all packets it * receives, no matter what. */ -static const struct nf_queue_handler __rcu *queue_handler __read_mostly; /* return EBUSY when somebody else is registered, return EEXIST if the * same handler is registered, return 0 in case of success. */ -void nf_register_queue_handler(const struct nf_queue_handler *qh) +void nf_register_queue_handler(struct net *net, const struct nf_queue_handler *qh) { /* should never happen, we only have one queueing backend in kernel */ - WARN_ON(rcu_access_pointer(queue_handler)); - rcu_assign_pointer(queue_handler, qh); + WARN_ON(rcu_access_pointer(net->nf.queue_handler)); + rcu_assign_pointer(net->nf.queue_handler, qh); } EXPORT_SYMBOL(nf_register_queue_handler); /* The caller must flush their queue before this */ -void nf_unregister_queue_handler(void) +void nf_unregister_queue_handler(struct net *net) { - RCU_INIT_POINTER(queue_handler, NULL); - synchronize_rcu(); + RCU_INIT_POINTER(net->nf.queue_handler, NULL); } EXPORT_SYMBOL(nf_unregister_queue_handler); @@ -103,7 +101,7 @@ void nf_queue_nf_hook_drop(struct net *net, struct nf_hook_ops *ops) const struct nf_queue_handler *qh; rcu_read_lock(); - qh = rcu_dereference(queue_handler); + qh = rcu_dereference(net->nf.queue_handler); if (qh) qh->nf_hook_drop(net, ops); rcu_read_unlock(); @@ -122,9 +120,10 @@ int nf_queue(struct sk_buff *skb, struct nf_queue_entry *entry = NULL; const struct nf_afinfo *afinfo; const struct nf_queue_handler *qh; + struct net *net = state->net; /* QUEUE == DROP if no one is waiting, to be safe. */ - qh = rcu_dereference(queue_handler); + qh = rcu_dereference(net->nf.queue_handler); if (!qh) { status = -ESRCH; goto err; diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c index e34256a0e7e9..309ac026aac2 100644 --- a/net/netfilter/nfnetlink_queue.c +++ b/net/netfilter/nfnetlink_queue.c @@ -1377,21 +1377,29 @@ static int __net_init nfnl_queue_net_init(struct net *net) net->nf.proc_netfilter, &nfqnl_file_ops)) return -ENOMEM; #endif + nf_register_queue_handler(net, &nfqh); return 0; } static void __net_exit nfnl_queue_net_exit(struct net *net) { + nf_unregister_queue_handler(net); #ifdef CONFIG_PROC_FS remove_proc_entry("nfnetlink_queue", net->nf.proc_netfilter); #endif } +static void nfnl_queue_net_exit_batch(struct list_head *net_exit_list) +{ + synchronize_rcu(); +} + static struct pernet_operations nfnl_queue_net_ops = { - .init = nfnl_queue_net_init, - .exit = nfnl_queue_net_exit, - .id = &nfnl_queue_net_id, - .size = sizeof(struct nfnl_queue_net), + .init = nfnl_queue_net_init, + .exit = nfnl_queue_net_exit, + .exit_batch = nfnl_queue_net_exit_batch, + .id = &nfnl_queue_net_id, + .size = sizeof(struct nfnl_queue_net), }; static int __init nfnetlink_queue_init(void) @@ -1412,7 +1420,6 @@ static int __init nfnetlink_queue_init(void) } register_netdevice_notifier(&nfqnl_dev_notifier); - nf_register_queue_handler(&nfqh); return status; cleanup_netlink_notifier: @@ -1424,7 +1431,6 @@ out: static void __exit nfnetlink_queue_fini(void) { - nf_unregister_queue_handler(); unregister_netdevice_notifier(&nfqnl_dev_notifier); nfnetlink_subsys_unregister(&nfqnl_subsys); netlink_unregister_notifier(&nfqnl_rtnl_notifier); |