idev->cnf.forwarding and net->ipv6.devconf_all->forwarding
might be read locklessly, add appropriate READ_ONCE()
and WRITE_ONCE() annotations.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In bhash2, IPv4/IPv6 addresses are saved in two union members,
which complicate address checks in inet_bind2_bucket_addr_match()
and inet_bind2_bucket_match_addr_any() considering uninitialised
memory and v4-mapped-v6 conflicts.

Let's simplify that by saving IPv4 address as v4-mapped-v6 address
and defining tb2.rcv_saddr as tb2.v6_rcv_saddr.s6_addr32[3].

Then, we can compare v6 address as is, and after checking v4-mapped-v6,
we can compare v4 address easily.  Also, we can remove tb2->family.

Note these functions will be further refactored in the next patch.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

At the moment ip6_dst_lookup_tunnel() is used only by bareudp.
Ideally, other UDP tunnel implementations should use it, but to do so
the function needs to accept new parameters that are specific for UDP
tunnels, such as the ports.

Prepare for these changes by renaming the function to
udp_tunnel6_dst_lookup() and move it to file
net/ipv6/ip6_udp_tunnel.c.

This is similar to what already done for IPv4 in commit bf3fcbf7e7a0
("ipv4: rename and move ip_route_output_tunnel()").

Suggested-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

We have data-races while reading np->srcprefs

Switch the field to a plain byte, add READ_ONCE()
and WRITE_ONCE() annotations where needed,
and IPV6_ADDR_PREFERENCES setsockopt() can now be lockless.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20230918142321.1794107-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

np->recverr is moved to inet->inet_flags to fix data-races.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Move np->dontfrag flag to inet->inet_flags to fix data-races.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Move np->autoflowlabel and np->autoflowlabel_set in inet->inet_flags,
to fix data-races.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

This fixes data-races around np->mcast_hops,
and make IPV6_MULTICAST_HOPS lockless.

Note that np->mcast_hops is never negative,
thus can fit an u8 field instead of s16.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Some np->hop_limit accesses are racy, when socket lock is not held.

Add missing annotations and switch to full lockless implementation.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Andrei Vagin reported bind() regression with strace logs.

If we bind() a TCPv6 socket to ::FFFF:0.0.0.0 and then bind() a TCPv4
socket to 127.0.0.1, the 2nd bind() should fail but now succeeds.

  from socket import *

  s1 = socket(AF_INET6, SOCK_STREAM)
  s1.bind(('::ffff:0.0.0.0', 0))

  s2 = socket(AF_INET, SOCK_STREAM)
  s2.bind(('127.0.0.1', s1.getsockname()[1]))

During the 2nd bind(), if tb->family is AF_INET6 and sk->sk_family is
AF_INET in inet_bind2_bucket_match_addr_any(), we still need to check
if tb has the v4-mapped-v6 wildcard address.

The example above does not work after commit 5456262d2baa ("net: Fix
incorrect address comparison when searching for a bind2 bucket"), but
the blamed change is not the commit.

Before the commit, the leading zeros of ::FFFF:0.0.0.0 were treated
as 0.0.0.0, and the sequence above worked by chance.  Technically, this
case has been broken since bhash2 was introduced.

Note that if we bind() two sockets to 127.0.0.1 and then ::FFFF:0.0.0.0,
the 2nd bind() fails properly because we fall back to using bhash to
detect conflicts for the v4-mapped-v6 address.

Fixes: 28044fc1d495 ("net: Add a bhash2 table hashed by port and address")
Reported-by: Andrei Vagin <avagin@google.com>
Closes: https://lore.kernel.org/netdev/ZPuYBOFC8zsK6r9T@google.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>