linux-stable.git/net/ipv6/ip6_input.c, branch v4.14.331

tcp/udp: Make early_demux back namespacified.

2022-11-10T14:47:22+00:00

commit 11052589cf5c0bab3b4884d423d5f60c38fcf25d upstream.

Commit e21145a9871a ("ipv4: namespacify ip_early_demux sysctl knob") made
it possible to enable/disable early_demux on a per-netns basis.  Then, we
introduced two knobs, tcp_early_demux and udp_early_demux, to switch it for
TCP/UDP in commit dddb64bcb346 ("net: Add sysctl to toggle early demux for
tcp and udp").  However, the .proc_handler() was wrong and actually
disabled us from changing the behaviour in each netns.

We can execute early_demux if net.ipv4.ip_early_demux is on and each proto
.early_demux() handler is not NULL.  When we toggle (tcp|udp)_early_demux,
the change itself is saved in each netns variable, but the .early_demux()
handler is a global variable, so the handler is switched based on the
init_net's sysctl variable.  Thus, netns (tcp|udp)_early_demux knobs have
nothing to do with the logic.  Whether we CAN execute proto .early_demux()
is always decided by init_net's sysctl knob, and whether we DO it or not is
by each netns ip_early_demux knob.

This patch namespacifies (tcp|udp)_early_demux again.  For now, the users
of the .early_demux() handler are TCP and UDP only, and they are called
directly to avoid retpoline.  So, we can remove the .early_demux() handler
from inet6?_protos and need not dereference them in ip6?_rcv_finish_core().
If another proto needs .early_demux(), we can restore it at that time.

Fixes: dddb64bcb346 ("net: Add sysctl to toggle early demux for tcp and udp")
Signed-off-by: Kuniyuki Iwashima 
Link: https://lore.kernel.org/r/20220713175207.7727-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

ipv6: weaken the v4mapped source check

2021-04-07T10:47:00+00:00

[ Upstream commit dcc32f4f183ab8479041b23a1525d48233df1d43 ]

This reverts commit 6af1799aaf3f1bc8defedddfa00df3192445bbf3.

Commit 6af1799aaf3f ("ipv6: drop incoming packets having a v4mapped
source address") introduced an input check against v4mapped addresses.
Use of such addresses on the wire is indeed questionable and not
allowed on public Internet. As the commit pointed out

  https://tools.ietf.org/html/draft-itojun-v6ops-v4mapped-harmful-02

lists potential issues.

Unfortunately there are applications which use v4mapped addresses,
and breaking them is a clear regression. For example v4mapped
addresses (or any semi-valid addresses, really) may be used
for uni-direction event streams or packet export.

Since the issue which sparked the addition of the check was with
TCP and request_socks in particular push the check down to TCPv6
and DCCP. This restores the ability to receive UDPv6 packets with
v4mapped address as the source.

Keep using the IPSTATS_MIB_INHDRERRORS statistic to minimize the
user-visible changes.

Fixes: 6af1799aaf3f ("ipv6: drop incoming packets having a v4mapped source address")
Reported-by: Sunyi Shao 
Signed-off-by: Jakub Kicinski 
Acked-by: Mat Martineau 
Reviewed-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

ipv6: drop incoming packets having a v4mapped source address

2019-10-07T16:55:16+00:00

[ Upstream commit 6af1799aaf3f1bc8defedddfa00df3192445bbf3 ]

This began with a syzbot report. syzkaller was injecting
IPv6 TCP SYN packets having a v4mapped source address.

After an unsuccessful 4-tuple lookup, TCP creates a request
socket (SYN_RECV) and calls reqsk_queue_hash_req()

reqsk_queue_hash_req() calls sk_ehashfn(sk)

At this point we have AF_INET6 sockets, and the heuristic
used by sk_ehashfn() to either hash the IPv4 or IPv6 addresses
is to use ipv6_addr_v4mapped(&sk->sk_v6_daddr)

For the particular spoofed packet, we end up hashing V4 addresses
which were not initialized by the TCP IPv6 stack, so KMSAN fired
a warning.

I first fixed sk_ehashfn() to test both source and destination addresses,
but then faced various problems, including user-space programs
like packetdrill that had similar assumptions.

Instead of trying to fix the whole ecosystem, it is better
to admit that we have a dual stack behavior, and that we
can not build linux kernels without V4 stack anyway.

The dual stack API automatically forces the traffic to be IPv4
if v4mapped addresses are used at bind() or connect(), so it makes
no sense to allow IPv6 traffic to use the same v4mapped class.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet 
Cc: Florian Westphal 
Cc: Hannes Frederic Sowa 
Reported-by: syzbot 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

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

2017-04-20T14:35:33+00:00

A function in kernel/bpf/syscall.c which got a bug fix in 'net'
was moved to kernel/bpf/verifier.c in 'net-next'.

Signed-off-by: David S. Miller

ipv6: drop non loopback packets claiming to originate from ::1

2017-04-17T19:09:23+00:00

We lack a saddr check for ::1. This causes security issues e.g. with acls
permitting connections from ::1 because of assumption that these originate
from local machine.

Assuming a source address of ::1 is local seems reasonable.
RFC4291 doesn't allow such a source address either, so drop such packets.

Reported-by: Eric Dumazet 
Signed-off-by: Florian Westphal 
Acked-by: Eric Dumazet 
Acked-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller

net: Add sysctl to toggle early demux for tcp and udp

2017-03-24T20:17:07+00:00

Certain system process significant unconnected UDP workload.
It would be preferrable to disable UDP early demux for those systems
and enable it for TCP only.

By disabling UDP demux, we see these slight gains on an ARM64 system-
782 -> 788Mbps unconnected single stream UDPv4
633 -> 654Mbps unconnected UDPv4 different sources

The performance impact can change based on CPU architecure and cache
sizes. There will not much difference seen if entire UDP hash table
is in cache.

Both sysctls are enabled by default to preserve existing behavior.

v1->v2: Change function pointer instead of adding conditional as
suggested by Stephen.

v2->v3: Read once in callers to avoid issues due to compiler
optimizations. Also update commit message with the tests.

v3->v4: Store and use read once result instead of querying pointer
again incorrectly.

v4->v5: Refactor to avoid errors due to compilation with IPV6={m,n}

Signed-off-by: Subash Abhinov Kasiviswanathan 
Suggested-by: Eric Dumazet 
Cc: Stephen Hemminger 
Cc: Tom Herbert 
Cc: David Miller 
Signed-off-by: David S. Miller

net: vrf: ipv6 support for local traffic to local addresses

2016-06-08T07:25:38+00:00

Add support for locally originated traffic to VRF-local IPv6 addresses.
Similar to IPv4 a local dst is set on the skb and the packet is
reinserted with a call to netif_rx. With this patch, ping, tcp and udp
packets to a local IPv6 address are successfully routed:

    $ ip addr show dev eth1
    4: eth1:  mtu 1500 qdisc pfifo_fast master red state UP group default qlen 1000
        link/ether 02:e0:f9:1c:b9:74 brd ff:ff:ff:ff:ff:ff
        inet 10.100.1.1/24 brd 10.100.1.255 scope global eth1
           valid_lft forever preferred_lft forever
        inet6 2100:1::1/120 scope global
           valid_lft forever preferred_lft forever
        inet6 fe80::e0:f9ff:fe1c:b974/64 scope link
           valid_lft forever preferred_lft forever

    $ ping6 -c1 -I red 2100:1::1
    ping6: Warning: source address might be selected on device other than red.
    PING 2100:1::1(2100:1::1) from 2100:1::1 red: 56 data bytes
    64 bytes from 2100:1::1: icmp_seq=1 ttl=64 time=0.098 ms

ip6_input is exported so the VRF driver can use it for the dst input
function. The dst_alloc function for IPv4 defaults to setting the input and
output functions; IPv6's does not. VRF does not need to duplicate the Rx path
so just export the ipv6 input function.

Signed-off-by: David Ahern 
Signed-off-by: David S. Miller

ipv6: Change "final" protocol processing for encapsulation

2016-05-20T22:03:16+00:00

When performing foo-over-UDP, UDP packets are processed by the
encapsulation handler which returns another protocol to process.
This may result in processing two (or more) protocols in the
loop that are marked as INET6_PROTO_FINAL. The actions taken
for hitting a final protocol, in particular the skb_postpull_rcsum
can only be performed once.

This patch set adds a check of a final protocol has been seen. The
rules are:
  - If the final protocol has not been seen any protocol is processed
    (final and non-final). In the case of a final protocol, the final
    actions are taken (like the skb_postpull_rcsum)
  - If a final protocol has been seen (e.g. an encapsulating UDP
    header) then no further non-final protocols are allowed
    (e.g. extension headers). For more final protocols the
    final actions are not taken (e.g. skb_postpull_rcsum).

Signed-off-by: Tom Herbert 
Signed-off-by: David S. Miller

ipv6: Fix nexthdr for reinjection

2016-05-20T22:03:16+00:00

In ip6_input_finish the nexthdr protocol is retrieved from the
next header offset that is returned in the cb of the skb.
This method does not work for UDP encapsulation that may not
even have a concept of a nexthdr field (e.g. FOU).

This patch checks for a final protocol (INET6_PROTO_FINAL) when a
protocol handler returns > 0. If the protocol is not final then
resubmission is performed on nhoff value. If the protocol is final
then the nexthdr is taken to be the return value.

Signed-off-by: Tom Herbert 
Signed-off-by: David S. Miller

net: l3mdev: Add hook in ip and ipv6

2016-05-11T23:31:40+00:00

Currently the VRF driver uses the rx_handler to switch the skb device
to the VRF device. Switching the dev prior to the ip / ipv6 layer
means the VRF driver has to duplicate IP/IPv6 processing which adds
overhead and makes features such as retaining the ingress device index
more complicated than necessary.

This patch moves the hook to the L3 layer just after the first NF_HOOK
for PRE_ROUTING. This location makes exposing the original ingress device
trivial (next patch) and allows adding other NF_HOOKs to the VRF driver
in the future.

dev_queue_xmit_nit is exported so that the VRF driver can cycle the skb
with the switched device through the packet taps to maintain current
behavior (tcpdump can be used on either the vrf device or the enslaved
devices).

Signed-off-by: David Ahern 
Signed-off-by: David S. Miller