linux-stable.git/net/ipv4/netfilter, branch v5.11

netfilter: rpfilter: mask ecn bits before fib lookup

2021-01-19T21:54:30+00:00

RT_TOS() only masks one of the two ECN bits. Therefore rpfilter_mt()
treats Not-ECT or ECT(1) packets in a different way than those with
ECT(0) or CE.

Reproducer:

  Create two netns, connected with a veth:
  $ ip netns add ns0
  $ ip netns add ns1
  $ ip link add name veth01 netns ns0 type veth peer name veth10 netns ns1
  $ ip -netns ns0 link set dev veth01 up
  $ ip -netns ns1 link set dev veth10 up
  $ ip -netns ns0 address add 192.0.2.10/32 dev veth01
  $ ip -netns ns1 address add 192.0.2.11/32 dev veth10

  Add a route to ns1 in ns0:
  $ ip -netns ns0 route add 192.0.2.11/32 dev veth01

  In ns1, only packets with TOS 4 can be routed to ns0:
  $ ip -netns ns1 route add 192.0.2.10/32 tos 4 dev veth10

  Ping from ns0 to ns1 works regardless of the ECN bits, as long as TOS
  is 4:
  $ ip netns exec ns0 ping -Q 4 192.0.2.11   # TOS 4, Not-ECT
    ... 0% packet loss ...
  $ ip netns exec ns0 ping -Q 5 192.0.2.11   # TOS 4, ECT(1)
    ... 0% packet loss ...
  $ ip netns exec ns0 ping -Q 6 192.0.2.11   # TOS 4, ECT(0)
    ... 0% packet loss ...
  $ ip netns exec ns0 ping -Q 7 192.0.2.11   # TOS 4, CE
    ... 0% packet loss ...

  Now use iptable's rpfilter module in ns1:
  $ ip netns exec ns1 iptables-legacy -t raw -A PREROUTING -m rpfilter --invert -j DROP

  Not-ECT and ECT(1) packets still pass:
  $ ip netns exec ns0 ping -Q 4 192.0.2.11   # TOS 4, Not-ECT
    ... 0% packet loss ...
  $ ip netns exec ns0 ping -Q 5 192.0.2.11   # TOS 4, ECT(1)
    ... 0% packet loss ...

  But ECT(0) and ECN packets are dropped:
  $ ip netns exec ns0 ping -Q 6 192.0.2.11   # TOS 4, ECT(0)
    ... 100% packet loss ...
  $ ip netns exec ns0 ping -Q 7 192.0.2.11   # TOS 4, CE
    ... 100% packet loss ...

After this patch, rpfilter doesn't drop ECT(0) and CE packets anymore.

Fixes: 8f97339d3feb ("netfilter: add ipv4 reverse path filter match")
Signed-off-by: Guillaume Nault 
Signed-off-by: Jakub Kicinski

netfilter: x_tables: Update remaining dereference to RCU

2020-12-17T18:44:52+00:00

This fixes the dereference to fetch the RCU pointer when holding
the appropriate xtables lock.

Reported-by: kernel test robot 
Fixes: cc00bcaa5899 ("netfilter: x_tables: Switch synchronization to RCU")
Signed-off-by: Subash Abhinov Kasiviswanathan 
Reviewed-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next

2020-12-14T23:43:21+00:00

Pablo Neira Ayuso says:

====================
Netfilter/IPVS updates for net-next

1) Missing dependencies in NFT_BRIDGE_REJECT, from Randy Dunlap.

2) Use atomic_inc_return() instead of atomic_add_return() in IPVS,
   from Yejune Deng.

3) Simplify check for overquota in xt_nfacct, from Kaixu Xia.

4) Move nfnl_acct_list away from struct net, from Miao Wang.

5) Pass actual sk in reject actions, from Jan Engelhardt.

6) Add timeout and protoinfo to ctnetlink destroy events,
   from Florian Westphal.

7) Four patches to generalize set infrastructure to support
   for multiple expressions per set element.

* git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next:
  netfilter: nftables: netlink support for several set element expressions
  netfilter: nftables: generalize set extension to support for several expressions
  netfilter: nftables: move nft_expr before nft_set
  netfilter: nftables: generalize set expressions support
  netfilter: ctnetlink: add timeout and protoinfo to destroy events
  netfilter: use actual socket sk for REJECT action
  netfilter: nfnl_acct: remove data from struct net
  netfilter: Remove unnecessary conversion to bool
  ipvs: replace atomic_add_return()
  netfilter: nft_reject_bridge: fix build errors due to code movement
====================

Link: https://lore.kernel.org/r/20201212230513.3465-1-pablo@netfilter.org
Signed-off-by: Jakub Kicinski

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2020-12-12T06:29:38+00:00

xdp_return_frame_bulk() needs to pass a xdp_buff
to __xdp_return().

strlcpy got converted to strscpy but here it makes no
functional difference, so just keep the right code.

Conflicts:
	net/netfilter/nf_tables_api.c

Signed-off-by: Jakub Kicinski

netfilter: x_tables: Switch synchronization to RCU

2020-12-08T11:57:39+00:00

When running concurrent iptables rules replacement with data, the per CPU
sequence count is checked after the assignment of the new information.
The sequence count is used to synchronize with the packet path without the
use of any explicit locking. If there are any packets in the packet path using
the table information, the sequence count is incremented to an odd value and
is incremented to an even after the packet process completion.

The new table value assignment is followed by a write memory barrier so every
CPU should see the latest value. If the packet path has started with the old
table information, the sequence counter will be odd and the iptables
replacement will wait till the sequence count is even prior to freeing the
old table info.

However, this assumes that the new table information assignment and the memory
barrier is actually executed prior to the counter check in the replacement
thread. If CPU decides to execute the assignment later as there is no user of
the table information prior to the sequence check, the packet path in another
CPU may use the old table information. The replacement thread would then free
the table information under it leading to a use after free in the packet
processing context-

Unable to handle kernel NULL pointer dereference at virtual
address 000000000000008e
pc : ip6t_do_table+0x5d0/0x89c
lr : ip6t_do_table+0x5b8/0x89c
ip6t_do_table+0x5d0/0x89c
ip6table_filter_hook+0x24/0x30
nf_hook_slow+0x84/0x120
ip6_input+0x74/0xe0
ip6_rcv_finish+0x7c/0x128
ipv6_rcv+0xac/0xe4
__netif_receive_skb+0x84/0x17c
process_backlog+0x15c/0x1b8
napi_poll+0x88/0x284
net_rx_action+0xbc/0x23c
__do_softirq+0x20c/0x48c

This could be fixed by forcing instruction order after the new table
information assignment or by switching to RCU for the synchronization.

Fixes: 80055dab5de0 ("netfilter: x_tables: make xt_replace_table wait until old rules are not used anymore")
Reported-by: Sean Tranchetti 
Reported-by: kernel test robot 
Suggested-by: Florian Westphal 
Signed-off-by: Subash Abhinov Kasiviswanathan 
Signed-off-by: Pablo Neira Ayuso

netfilter: use actual socket sk for REJECT action

2020-12-01T13:33:55+00:00

True to the message of commit v5.10-rc1-105-g46d6c5ae953c, _do_
actually make use of state->sk when possible, such as in the REJECT
modules.

Reported-by: Minqiang Chen 
Cc: Jason A. Donenfeld 
Signed-off-by: Jan Engelhardt 
Signed-off-by: Pablo Neira Ayuso

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2020-11-07T01:33:38+00:00

Signed-off-by: Jakub Kicinski

netfilter: nft_reject_inet: allow to use reject from inet ingress

2020-11-01T11:52:17+00:00

Enhance validation to support for reject from inet ingress chains.

Note that, reject from inet ingress and netdev ingress differ.

Reject packets from inet ingress are sent through ip_local_out() since
inet reject emulates the IP layer receive path. So the reject packet
follows to classic IP output and postrouting paths.

The reject action from netdev ingress assumes the packet not yet entered
the IP layer, so the reject packet is sent through dev_queue_xmit().
Therefore, reject packets from netdev ingress do not follow the classic
IP output and postrouting paths.

Signed-off-by: Pablo Neira Ayuso

netfilter: nf_reject: add reject skbuff creation helpers

2020-10-31T09:40:22+00:00

Adds reject skbuff creation helper functions to ipv4/6 nf_reject
infrastructure. Use these functions for reject verdict in bridge
family.

Can be reused by all different families that support reject and
will not inject the reject packet through ip local out.

Signed-off-by: Jose M. Guisado Gomez 
Signed-off-by: Pablo Neira Ayuso

netfilter: use actual socket sk rather than skb sk when routing harder

2020-10-30T11:57:39+00:00

If netfilter changes the packet mark when mangling, the packet is
rerouted using the route_me_harder set of functions. Prior to this
commit, there's one big difference between route_me_harder and the
ordinary initial routing functions, described in the comment above
__ip_queue_xmit():

   /* Note: skb->sk can be different from sk, in case of tunnels */
   int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,

That function goes on to correctly make use of sk->sk_bound_dev_if,
rather than skb->sk->sk_bound_dev_if. And indeed the comment is true: a
tunnel will receive a packet in ndo_start_xmit with an initial skb->sk.
It will make some transformations to that packet, and then it will send
the encapsulated packet out of a *new* socket. That new socket will
basically always have a different sk_bound_dev_if (otherwise there'd be
a routing loop). So for the purposes of routing the encapsulated packet,
the routing information as it pertains to the socket should come from
that socket's sk, rather than the packet's original skb->sk. For that
reason __ip_queue_xmit() and related functions all do the right thing.

One might argue that all tunnels should just call skb_orphan(skb) before
transmitting the encapsulated packet into the new socket. But tunnels do
*not* do this -- and this is wisely avoided in skb_scrub_packet() too --
because features like TSQ rely on skb->destructor() being called when
that buffer space is truely available again. Calling skb_orphan(skb) too
early would result in buffers filling up unnecessarily and accounting
info being all wrong. Instead, additional routing must take into account
the new sk, just as __ip_queue_xmit() notes.

So, this commit addresses the problem by fishing the correct sk out of
state->sk -- it's already set properly in the call to nf_hook() in
__ip_local_out(), which receives the sk as part of its normal
functionality. So we make sure to plumb state->sk through the various
route_me_harder functions, and then make correct use of it following the
example of __ip_queue_xmit().

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jason A. Donenfeld 
Reviewed-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso