linux/net/netfilter, branch v4.11

netfilter: nft_hash: do not dump the auto generated seed

2017-04-13T21:20:13Z

This can prevent the nft utility from printing out the auto generated seed to the user, which is unnecessary and confusing. Fixes: cb1b69b0b15b ("netfilter: nf_tables: add hash expression") Signed-off-by: Liping Zhang Signed-off-by: Pablo Neira Ayuso

netfilter: nf_ct_expect: use proper RCU list traversal/update APIs

2017-04-08T21:52:17Z

We should use proper RCU list APIs to manipulate help->expectations, as we can dump the conntrack's expectations via nfnetlink, i.e. in ctnetlink_exp_ct_dump_table(), where only rcu_read_lock is acquired. So for list traversal, use hlist_for_each_entry_rcu; for list add/del, use hlist_add_head_rcu and hlist_del_rcu. Signed-off-by: Liping Zhang Signed-off-by: Pablo Neira Ayuso

netfilter: ctnetlink: skip dumping expect when nfct_help(ct) is NULL

2017-04-08T21:52:17Z

For IPCTNL_MSG_EXP_GET, if the CTA_EXPECT_MASTER attr is specified, then the NLM_F_DUMP request will dump the expectations related to this connection tracking. But we forget to check whether the conntrack has nf_conn_help or not, so if nfct_help(ct) is NULL, oops will happen: BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 IP: ctnetlink_exp_ct_dump_table+0xf9/0x1e0 [nf_conntrack_netlink] Call Trace: ? ctnetlink_exp_ct_dump_table+0x75/0x1e0 [nf_conntrack_netlink] netlink_dump+0x124/0x2a0 __netlink_dump_start+0x161/0x190 ctnetlink_dump_exp_ct+0x16c/0x1bc [nf_conntrack_netlink] ? ctnetlink_exp_fill_info.constprop.33+0xf0/0xf0 [nf_conntrack_netlink] ? ctnetlink_glue_seqadj+0x20/0x20 [nf_conntrack_netlink] ctnetlink_get_expect+0x32e/0x370 [nf_conntrack_netlink] ? debug_lockdep_rcu_enabled+0x1d/0x20 nfnetlink_rcv_msg+0x60a/0x6a9 [nfnetlink] ? nfnetlink_rcv_msg+0x1b9/0x6a9 [nfnetlink] [...] Signed-off-by: Liping Zhang Signed-off-by: Pablo Neira Ayuso

netfilter: make it safer during the inet6_dev->addr_list traversal

2017-04-08T21:52:16Z

inet6_dev->addr_list is protected by inet6_dev->lock, so only using rcu_read_lock is not enough, we should acquire read_lock_bh(&idev->lock) before the inet6_dev->addr_list traversal. Signed-off-by: Liping Zhang Signed-off-by: Pablo Neira Ayuso

netfilter: ctnetlink: make it safer when checking the ct helper name

2017-04-08T21:52:16Z

One CPU is doing ctnetlink_change_helper(), while another CPU is doing unhelp() at the same time. So even if help->helper is not NULL at first, the later statement strcmp(help->helper->name, ...) may still access the NULL pointer. So we must use rcu_read_lock and rcu_dereference to avoid such _bad_ thing happen. Fixes: f95d7a46bc57 ("netfilter: ctnetlink: Fix regression in CTA_HELP processing") Signed-off-by: Liping Zhang Signed-off-by: Pablo Neira Ayuso

netfilter: helper: Add the rcu lock when call __nf_conntrack_helper_find

2017-04-08T21:52:15Z

When invoke __nf_conntrack_helper_find, it needs the rcu lock to protect the helper module which would not be unloaded. Now there are two caller nf_conntrack_helper_try_module_get and ctnetlink_create_expect which don't hold rcu lock. And the other callers left like ctnetlink_change_helper, ctnetlink_create_conntrack, and ctnetlink_glue_attach_expect, they already hold the rcu lock or spin_lock_bh. Remove the rcu lock in functions nf_ct_helper_expectfn_find_by_name and nf_ct_helper_expectfn_find_by_symbol. Because they return one pointer which needs rcu lock, so their caller should hold the rcu lock, not in these two functions. Signed-off-by: Gao Feng Signed-off-by: Pablo Neira Ayuso

netfilter: ctnetlink: using bit to represent the ct event

2017-04-08T21:52:15Z

Otherwise, creating a new conntrack via nfnetlink: # conntrack -I -p udp -s 1.1.1.1 -d 2.2.2.2 -t 10 --sport 10 --dport 20 will emit the wrong ct events(where UPDATE should be NEW): # conntrack -E [UPDATE] udp 17 10 src=1.1.1.1 dst=2.2.2.2 sport=10 dport=20 [UNREPLIED] src=2.2.2.2 dst=1.1.1.1 sport=20 dport=10 mark=0 Signed-off-by: Liping Zhang Signed-off-by: Pablo Neira Ayuso

netfilter: xt_TCPMSS: add more sanity tests on tcph->doff

2017-04-08T20:24:19Z

Denys provided an awesome KASAN report pointing to an use after free in xt_TCPMSS I have provided three patches to fix this issue, either in xt_TCPMSS or in xt_tcpudp.c. It seems xt_TCPMSS patch has the smallest possible impact. Signed-off-by: Eric Dumazet Reported-by: Denys Fedoryshchenko Signed-off-by: Pablo Neira Ayuso

netfilter: nfnetlink_queue: fix secctx memory leak

2017-03-29T10:20:50Z

We must call security_release_secctx to free the memory returned by security_secid_to_secctx, otherwise memory may be leaked forever. Fixes: ef493bd930ae ("netfilter: nfnetlink_queue: add security context information") Signed-off-by: Liping Zhang Signed-off-by: Pablo Neira Ayuso

netfilter: nf_ct_ext: fix possible panic after nf_ct_extend_unregister

2017-03-27T11:47:29Z

If one cpu is doing nf_ct_extend_unregister while another cpu is doing __nf_ct_ext_add_length, then we may hit BUG_ON(t == NULL). Moreover, there's no synchronize_rcu invocation after set nf_ct_ext_types[id] to NULL, so it's possible that we may access invalid pointer. But actually, most of the ct extends are built-in, so the problem listed above will not happen. However, there are two exceptions: NF_CT_EXT_NAT and NF_CT_EXT_SYNPROXY. For _EXT_NAT, the panic will not happen, since adding the nat extend and unregistering the nat extend are located in the same file(nf_nat_core.c), this means that after the nat module is removed, we cannot add the nat extend too. For _EXT_SYNPROXY, synproxy extend may be added by init_conntrack, while synproxy extend unregister will be done by synproxy_core_exit. So after nf_synproxy_core.ko is removed, we may still try to add the synproxy extend, then kernel panic may happen. I know it's very hard to reproduce this issue, but I can play a tricky game to make it happen very easily :) Step 1. Enable SYNPROXY for tcp dport 1234 at FORWARD hook: # iptables -I FORWARD -p tcp --dport 1234 -j SYNPROXY Step 2. Queue the syn packet to the userspace at raw table OUTPUT hook. Also note, in the userspace we only add a 20s' delay, then reinject the syn packet to the kernel: # iptables -t raw -I OUTPUT -p tcp --syn -j NFQUEUE --queue-num 1 Step 3. Using "nc 2.2.2.2 1234" to connect the server. Step 4. Now remove the nf_synproxy_core.ko quickly: # iptables -F FORWARD # rmmod ipt_SYNPROXY # rmmod nf_synproxy_core Step 5. After 20s' delay, the syn packet is reinjected to the kernel. Now you will see the panic like this: kernel BUG at net/netfilter/nf_conntrack_extend.c:91! Call Trace: ? __nf_ct_ext_add_length+0x53/0x3c0 [nf_conntrack] init_conntrack+0x12b/0x600 [nf_conntrack] nf_conntrack_in+0x4cc/0x580 [nf_conntrack] ipv4_conntrack_local+0x48/0x50 [nf_conntrack_ipv4] nf_reinject+0x104/0x270 nfqnl_recv_verdict+0x3e1/0x5f9 [nfnetlink_queue] ? nfqnl_recv_verdict+0x5/0x5f9 [nfnetlink_queue] ? nla_parse+0xa0/0x100 nfnetlink_rcv_msg+0x175/0x6a9 [nfnetlink] [...] One possible solution is to make NF_CT_EXT_SYNPROXY extend built-in, i.e. introduce nf_conntrack_synproxy.c and only do ct extend register and unregister in it, similar to nf_conntrack_timeout.c. But having such a obscure restriction of nf_ct_extend_unregister is not a good idea, so we should invoke synchronize_rcu after set nf_ct_ext_types to NULL, and check the NULL pointer when do __nf_ct_ext_add_length. Then it will be easier if we add new ct extend in the future. Last, we use kfree_rcu to free nf_ct_ext, so rcu_barrier() is unnecessary anymore, remove it too. Signed-off-by: Liping Zhang Acked-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso