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Code Activity

ipv6: Remove IPV6_ADDRFORM.

Browse Source 
Recently, IPV6_ADDRFORM has received many AI-driven bug reports.
Fixing them properly would needlessly churn the fast paths in TCP
and UDP.

IPV6_ADDRFORM was initially introduced in RFC 2133 in 1997,
but only two years later, it was removed from RFC 2553 in 1999.

In 2026, modern applications natively support dual-stack sockets;
notably, systemd's socket activation does not use IPV6_ADDRFORM.

Also, getsockopt(IPV6_ADDRFORM) can be replaced with SO_DOMAIN.

Let's remove IPV6_ADDRFORM.

Later, we can remove sk->sk_prot_creator and revert commit
c26c192c3d ("udp: properly deal with xfrm encap and ADDRFORM").

Reported-by: Daehyeon Ko <4ncienth@gmail.com>
Closes: https://lore.kernel.org/netdev/20260902010408.1057857-1-4ncienth@gmail.com/
Reported-by: Hyunwoo Kim <imv4bel@gmail.com>
Closes: https://lore.kernel.org/netdev/20260824033331.1084971-1-imv4bel@gmail.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260904033543.2635540-3-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima authored and Jakub Kicinski committed 2026-09-07 17:40:26 -07:00
1 parent 8cc3aef0cb
commit 31c5ea8a32
5 files changed
+2 -98
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include/linux/net.h
+1 -1
View File
@@ -166,7 +166,7 @@ struct socket {
struct file *file;
struct sock *sk;
const struct proto_ops *ops; /* Might change with IPV6_ADDRFORM or MPTCP. */
const struct proto_ops *ops; /* Might change with MPTCP. */
struct socket_wq wq;
};
net/core/sock.c
+1 -3
View File
@@ -770,7 +770,7 @@ bool sk_mc_loop(const struct sock *sk)
return false;
if (!sk)
return true;
/* IPV6_ADDRFORM can change sk->sk_family under us. */
switch (READ_ONCE(sk->sk_family)) {
case AF_INET:
return inet_test_bit(MC_LOOP, sk);
@@ -4010,7 +4010,6 @@ int sock_common_getsockopt(struct socket *sock, int level, int optname,
{
struct sock *sk = sock->sk;
/* IPV6_ADDRFORM can change sk->sk_prot under us. */
return READ_ONCE(sk->sk_prot)->getsockopt(sk, level, optname, optval, optlen);
}
EXPORT_SYMBOL(sock_common_getsockopt);
@@ -4032,7 +4031,6 @@ int sock_common_setsockopt(struct socket *sock, int level, int optname,
{
struct sock *sk = sock->sk;
/* IPV6_ADDRFORM can change sk->sk_prot under us. */
return READ_ONCE(sk->sk_prot)->setsockopt(sk, level, optname, optval, optlen);
}
EXPORT_SYMBOL(sock_common_setsockopt);
net/ipv4/af_inet.c
-3
View File
@@ -582,7 +582,6 @@ int inet_dgram_connect(struct socket *sock, struct sockaddr_unsized *uaddr,
if (addr_len < sizeof(uaddr->sa_family))
return -EINVAL;
/* IPV6_ADDRFORM can change sk->sk_prot under us. */
prot = READ_ONCE(sk->sk_prot);
if (uaddr->sa_family == AF_UNSPEC)
@@ -789,7 +788,6 @@ int inet_accept(struct socket *sock, struct socket *newsock,
{
struct sock *sk1 = sock->sk, *sk2;
/* IPV6_ADDRFORM can change sk->sk_prot under us. */
arg->err = -EINVAL;
sk2 = READ_ONCE(sk1->sk_prot)->accept(sk1, arg);
if (!sk2)
@@ -875,7 +873,6 @@ void inet_splice_eof(struct socket *sock)
if (unlikely(inet_send_prepare(sk)))
return;
/* IPV6_ADDRFORM can change sk->sk_prot under us. */
prot = READ_ONCE(sk->sk_prot);
if (prot->splice_eof)
prot->splice_eof(sock);
net/ipv6/af_inet6.c
-4
View File
@@ -429,7 +429,6 @@ int inet6_bind_sk(struct sock *sk, struct sockaddr_unsized *uaddr, int addr_len)
const struct proto *prot;
int err = 0;
/* IPV6_ADDRFORM can change sk->sk_prot under us. */
prot = READ_ONCE(sk->sk_prot);
/* If the socket has its own bind function then use it. */
if (prot->bind)
@@ -567,7 +566,6 @@ int inet6_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
case SIOCSIFDSTADDR:
return addrconf_set_dstaddr(net, argp);
default:
/* IPV6_ADDRFORM can change sk->sk_prot under us. */
prot = READ_ONCE(sk->sk_prot);
if (!prot->ioctl)
return -ENOIOCTLCMD;
@@ -636,7 +634,6 @@ int inet6_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
if (unlikely(inet_send_prepare(sk)))
return -EAGAIN;
/* IPV6_ADDRFORM can change sk->sk_prot under us. */
prot = READ_ONCE(sk->sk_prot);
return INDIRECT_CALL_2(prot->sendmsg, tcp_sendmsg, udpv6_sendmsg,
sk, msg, size);
@@ -651,7 +648,6 @@ int inet6_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
if (likely(!(flags & MSG_ERRQUEUE)))
sock_rps_record_flow(sk);
/* IPV6_ADDRFORM can change sk->sk_prot under us. */
prot = READ_ONCE(sk->sk_prot);
return INDIRECT_CALL_2(prot->recvmsg, tcp_recvmsg, udpv6_recvmsg,
sk, msg, size, flags);
net/ipv6/ipv6_sockglue.c
-87
View File
@@ -547,86 +547,7 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
sockopt_lock_sock(sk);
/* Another thread has converted the socket into IPv4 with
* IPV6_ADDRFORM concurrently.
*/
if (unlikely(sk->sk_family != AF_INET6))
goto unlock;
switch (optname) {
case IPV6_ADDRFORM:
if (optlen < sizeof(int))
goto e_inval;
if (val == PF_INET) {
if (sk->sk_type == SOCK_RAW)
break;
if (sk->sk_protocol == IPPROTO_UDP) {
if (udp_sk(sk)->pending == AF_INET6) {
retv = -EBUSY;
break;
}
} else if (sk->sk_protocol == IPPROTO_TCP) {
if (sk->sk_prot != &tcpv6_prot) {
retv = -EBUSY;
break;
}
} else {
break;
}
if (sk->sk_state != TCP_ESTABLISHED) {
retv = -ENOTCONN;
break;
}
if (ipv6_only_sock(sk) ||
!ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
retv = -EADDRNOTAVAIL;
break;
}
__ipv6_sock_mc_close(sk);
__ipv6_sock_ac_close(sk);
if (sk->sk_protocol == IPPROTO_TCP) {
struct inet_connection_sock *icsk = inet_csk(sk);
sock_prot_inuse_add(net, sk->sk_prot, -1);
sock_prot_inuse_add(net, &tcp_prot, 1);
/* Paired with READ_ONCE(sk->sk_prot) in inet6_stream_ops */
WRITE_ONCE(sk->sk_prot, &tcp_prot);
/* Paired with READ_ONCE() in tcp_(get|set)sockopt() */
WRITE_ONCE(icsk->icsk_af_ops, &ipv4_specific);
WRITE_ONCE(sk->sk_socket->ops, &inet_stream_ops);
WRITE_ONCE(sk->sk_family, PF_INET);
tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
} else {
sock_prot_inuse_add(net, sk->sk_prot, -1);
sock_prot_inuse_add(net, &udp_prot, 1);
/* Paired with READ_ONCE(sk->sk_prot) in inet6_dgram_ops */
WRITE_ONCE(sk->sk_prot, &udp_prot);
WRITE_ONCE(sk->sk_socket->ops, &inet_dgram_ops);
WRITE_ONCE(sk->sk_family, PF_INET);
}
/* Disable all options not to allocate memory anymore,
* but there is still a race. See the lockless path
* in udpv6_sendmsg() and ipv6_local_rxpmtu().
*/
np->rxopt.all = 0;
inet6_cleanup_sock(sk);
module_put(THIS_MODULE);
retv = 0;
break;
}
goto e_inval;
case IPV6_V6ONLY:
if (optlen < sizeof(int) ||
inet_sk(sk)->inet_num)
@@ -1088,14 +1009,6 @@ int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
if (copy_from_sockptr(&len, optlen, sizeof(int)))
return -EFAULT;
switch (optname) {
case IPV6_ADDRFORM:
if (sk->sk_protocol != IPPROTO_UDP &&
sk->sk_protocol != IPPROTO_TCP)
return -ENOPROTOOPT;
if (sk->sk_state != TCP_ESTABLISHED)
return -ENOTCONN;
val = sk->sk_family;
break;
case MCAST_MSFILTER:
if (in_compat_syscall())
return compat_ipv6_get_msfilter(sk, optval, optlen, len);