linux-stable.git/net/ipv4, branch v5.4.89

netfilter: x_tables: Update remaining dereference to RCU

2021-01-12T19:16:24+00:00

commit 443d6e86f821a165fae3fc3fc13086d27ac140b1 upstream.

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 
Signed-off-by: Greg Kroah-Hartman

erspan: fix version 1 check in gre_parse_header()

2021-01-12T19:16:15+00:00

[ Upstream commit 085c7c4e1c0e50d90b7d90f61a12e12b317a91e2 ]

Both version 0 and version 1 use ETH_P_ERSPAN, but version 0 does not
have an erspan header. So the check in gre_parse_header() is wrong,
we have to distinguish version 1 from version 0.

We can just check the gre header length like is_erspan_type1().

Fixes: cb73ee40b1b3 ("net: ip_gre: use erspan key field for tunnel lookup")
Reported-by: syzbot+f583ce3d4ddf9836b27a@syzkaller.appspotmail.com
Cc: William Tu 
Cc: Lorenzo Bianconi 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv4: Ignore ECN bits for fib lookups in fib_compute_spec_dst()

2021-01-12T19:16:14+00:00

[ Upstream commit 21fdca22eb7df2a1e194b8adb812ce370748b733 ]

RT_TOS() only clears one of the ECN bits. Therefore, when
fib_compute_spec_dst() resorts to a fib lookup, it can return
different results depending on the value of the second ECN bit.

For example, ECT(0) and ECT(1) packets could be treated differently.

  $ 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 lo up
  $ ip -netns ns1 link set dev lo up
  $ ip -netns ns0 link set dev veth01 up
  $ ip -netns ns1 link set dev veth10 up

  $ ip -netns ns0 address add 192.0.2.10/24 dev veth01
  $ ip -netns ns1 address add 192.0.2.11/24 dev veth10

  $ ip -netns ns1 address add 192.0.2.21/32 dev lo
  $ ip -netns ns1 route add 192.0.2.10/32 tos 4 dev veth10 src 192.0.2.21
  $ ip netns exec ns1 sysctl -wq net.ipv4.icmp_echo_ignore_broadcasts=0

With TOS 4 and ECT(1), ns1 replies using source address 192.0.2.21
(ping uses -Q to set all TOS and ECN bits):

  $ ip netns exec ns0 ping -c 1 -b -Q 5 192.0.2.255
  [...]
  64 bytes from 192.0.2.21: icmp_seq=1 ttl=64 time=0.544 ms

But with TOS 4 and ECT(0), ns1 replies using source address 192.0.2.11
because the "tos 4" route isn't matched:

  $ ip netns exec ns0 ping -c 1 -b -Q 6 192.0.2.255
  [...]
  64 bytes from 192.0.2.11: icmp_seq=1 ttl=64 time=0.597 ms

After this patch the ECN bits don't affect the result anymore:

  $ ip netns exec ns0 ping -c 1 -b -Q 6 192.0.2.255
  [...]
  64 bytes from 192.0.2.21: icmp_seq=1 ttl=64 time=0.591 ms

Fixes: 35ebf65e851c ("ipv4: Create and use fib_compute_spec_dst() helper.")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

netfilter: x_tables: Switch synchronization to RCU

2020-12-30T10:50:54+00:00

[ Upstream commit cc00bcaa589914096edef7fb87ca5cee4a166b5c ]

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 
Signed-off-by: Sasha Levin

tcp: fix cwnd-limited bug for TSO deferral where we send nothing

2020-12-21T12:27:04+00:00

[ Upstream commit 299bcb55ecd1412f6df606e9dc0912d55610029e ]

When cwnd is not a multiple of the TSO skb size of N*MSS, we can get
into persistent scenarios where we have the following sequence:

(1) ACK for full-sized skb of N*MSS arrives
  -> tcp_write_xmit() transmit full-sized skb with N*MSS
  -> move pacing release time forward
  -> exit tcp_write_xmit() because pacing time is in the future

(2) TSQ callback or TCP internal pacing timer fires
  -> try to transmit next skb, but TSO deferral finds remainder of
     available cwnd is not big enough to trigger an immediate send
     now, so we defer sending until the next ACK.

(3) repeat...

So we can get into a case where we never mark ourselves as
cwnd-limited for many seconds at a time, even with
bulk/infinite-backlog senders, because:

o In case (1) above, every time in tcp_write_xmit() we have enough
cwnd to send a full-sized skb, we are not fully using the cwnd
(because cwnd is not a multiple of the TSO skb size). So every time we
send data, we are not cwnd limited, and so in the cwnd-limited
tracking code in tcp_cwnd_validate() we mark ourselves as not
cwnd-limited.

o In case (2) above, every time in tcp_write_xmit() that we try to
transmit the "remainder" of the cwnd but defer, we set the local
variable is_cwnd_limited to true, but we do not send any packets, so
sent_pkts is zero, so we don't call the cwnd-limited logic to update
tp->is_cwnd_limited.

Fixes: ca8a22634381 ("tcp: make cwnd-limited checks measurement-based, and gentler")
Reported-by: Ingemar Johansson 
Signed-off-by: Neal Cardwell 
Signed-off-by: Yuchung Cheng 
Acked-by: Soheil Hassas Yeganeh 
Signed-off-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20201209035759.1225145-1-ncardwell.kernel@gmail.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

tcp: select sane initial rcvq_space.space for big MSS

2020-12-21T12:27:04+00:00

[ Upstream commit 72d05c00d7ecda85df29abd046da7e41cc071c17 ]

Before commit a337531b942b ("tcp: up initial rmem to 128KB and SYN rwin to around 64KB")
small tcp_rmem[1] values were overridden by tcp_fixup_rcvbuf() to accommodate various MSS.

This is no longer the case, and Hazem Mohamed Abuelfotoh reported
that DRS would not work for MTU 9000 endpoints receiving regular (1500 bytes) frames.

Root cause is that tcp_init_buffer_space() uses tp->rcv_wnd for upper limit
of rcvq_space.space computation, while it can select later a smaller
value for tp->rcv_ssthresh and tp->window_clamp.

ss -temoi on receiver would show :

skmem:(r0,rb131072,t0,tb46080,f0,w0,o0,bl0,d0) rcv_space:62496 rcv_ssthresh:56596

This means that TCP can not increase its window in tcp_grow_window(),
and that DRS can never kick.

Fix this by making sure that rcvq_space.space is not bigger than number of bytes
that can be held in TCP receive queue.

People unable/unwilling to change their kernel can work around this issue by
selecting a bigger tcp_rmem[1] value as in :

echo "4096 196608 6291456" >/proc/sys/net/ipv4/tcp_rmem

Based on an initial report and patch from Hazem Mohamed Abuelfotoh
 https://lore.kernel.org/netdev/20201204180622.14285-1-abuehaze@amazon.com/

Fixes: a337531b942b ("tcp: up initial rmem to 128KB and SYN rwin to around 64KB")
Fixes: 041a14d26715 ("tcp: start receiver buffer autotuning sooner")
Reported-by: Hazem Mohamed Abuelfotoh 
Signed-off-by: Eric Dumazet 
Acked-by: Soheil Hassas Yeganeh 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

udp: fix the proto value passed to ip_protocol_deliver_rcu for the segments

2020-12-21T12:27:03+00:00

[ Upstream commit 10c678bd0a035ac2c64a9b26b222f20556227a53 ]

Guillaume noticed that: for segments udp_queue_rcv_one_skb() returns the
proto, and it should pass "ret" unmodified to ip_protocol_deliver_rcu().
Otherwize, with a negtive value passed, it will underflow inet_protos.

This can be reproduced with IPIP FOU:

  # ip fou add port 5555 ipproto 4
  # ethtool -K eth1 rx-gro-list on

Fixes: cf329aa42b66 ("udp: cope with UDP GRO packet misdirection")
Reported-by: Guillaume Nault 
Signed-off-by: Xin Long 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv4: fix error return code in rtm_to_fib_config()

2020-12-21T12:27:03+00:00

[ Upstream commit b410f04eb5b482b5efc4eee90de81ad35d3d923b ]

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: d15662682db2 ("ipv4: Allow ipv6 gateway with ipv4 routes")
Reported-by: Hulk Robot 
Signed-off-by: Zhang Changzhong 
Reviewed-by: David Ahern 
Link: https://lore.kernel.org/r/1607071695-33740-1-git-send-email-zhangchangzhong@huawei.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

ipv4: Fix tos mask in inet_rtm_getroute()

2020-12-08T09:40:25+00:00

[ Upstream commit 1ebf179037cb46c19da3a9c1e2ca16e7a754b75e ]

When inet_rtm_getroute() was converted to use the RCU variants of
ip_route_input() and ip_route_output_key(), the TOS parameters
stopped being masked with IPTOS_RT_MASK before doing the route lookup.

As a result, "ip route get" can return a different route than what
would be used when sending real packets.

For example:

    $ ip route add 192.0.2.11/32 dev eth0
    $ ip route add unreachable 192.0.2.11/32 tos 2
    $ ip route get 192.0.2.11 tos 2
    RTNETLINK answers: No route to host

But, packets with TOS 2 (ECT(0) if interpreted as an ECN bit) would
actually be routed using the first route:

    $ ping -c 1 -Q 2 192.0.2.11
    PING 192.0.2.11 (192.0.2.11) 56(84) bytes of data.
    64 bytes from 192.0.2.11: icmp_seq=1 ttl=64 time=0.173 ms

    --- 192.0.2.11 ping statistics ---
    1 packets transmitted, 1 received, 0% packet loss, time 0ms
    rtt min/avg/max/mdev = 0.173/0.173/0.173/0.000 ms

This patch re-applies IPTOS_RT_MASK in inet_rtm_getroute(), to
return results consistent with real route lookups.

Fixes: 3765d35ed8b9 ("net: ipv4: Convert inet_rtm_getroute to rcu versions of route lookup")
Signed-off-by: Guillaume Nault 
Reviewed-by: David Ahern 
Link: https://lore.kernel.org/r/b2d237d08317ca55926add9654a48409ac1b8f5b.1606412894.git.gnault@redhat.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

tcp: Set INET_ECN_xmit configuration in tcp_reinit_congestion_control

2020-12-08T09:40:24+00:00

[ Upstream commit 55472017a4219ca965a957584affdb17549ae4a4 ]

When setting congestion control via a BPF program it is seen that the
SYN/ACK for packets within a given flow will not include the ECT0 flag. A
bit of simple printk debugging shows that when this is configured without
BPF we will see the value INET_ECN_xmit value initialized in
tcp_assign_congestion_control however when we configure this via BPF the
socket is in the closed state and as such it isn't configured, and I do not
see it being initialized when we transition the socket into the listen
state. The result of this is that the ECT0 bit is configured based on
whatever the default state is for the socket.

Any easy way to reproduce this is to monitor the following with tcpdump:
tools/testing/selftests/bpf/test_progs -t bpf_tcp_ca

Without this patch the SYN/ACK will follow whatever the default is. If dctcp
all SYN/ACK packets will have the ECT0 bit set, and if it is not then ECT0
will be cleared on all SYN/ACK packets. With this patch applied the SYN/ACK
bit matches the value seen on the other packets in the given stream.

Fixes: 91b5b21c7c16 ("bpf: Add support for changing congestion control")
Signed-off-by: Alexander Duyck 
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman