x25: convert to getsockopt_iter

Convert X.25 socket's getsockopt implementation to use the new
getsockopt_iter callback with sockopt_t.

Key changes:
- Replace (char __user *optval, int __user *optlen) with sockopt_t *opt
- Use opt->optlen for buffer length (input) and returned size (output)
- Use copy_to_iter() instead of put_user()/copy_to_user()
- Add linux/uio.h for copy_to_iter()

Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20260507-getsock_two-v2-3-5873111d9c12@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/x25/af_x25.c

diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index af8762b..c31d2af 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -53,6 +53,7 @@
 #include <linux/init.h>
 #include <linux/compat.h>
 #include <linux/ctype.h>
+#include <linux/uio.h>
 
 #include <net/x25.h>
 #include <net/compat.h>
@@ -448,7 +449,7 @@ static int x25_setsockopt(struct socket *sock, int level, int optname,
 }
 
 static int x25_getsockopt(struct socket *sock, int level, int optname,
-			  char __user *optval, int __user *optlen)
+			  sockopt_t *opt)
 {
 	struct sock *sk = sock->sk;
 	int val, len, rc = -ENOPROTOOPT;
@@ -456,22 +457,17 @@ static int x25_getsockopt(struct socket *sock, int level, int optname,
 	if (level != SOL_X25 || optname != X25_QBITINCL)
 		goto out;
 
-	rc = -EFAULT;
-	if (get_user(len, optlen))
-		goto out;
+	len = opt->optlen;
 
 	rc = -EINVAL;
 	if (len < 0)
 		goto out;
 
 	len = min_t(unsigned int, len, sizeof(int));
-
-	rc = -EFAULT;
-	if (put_user(len, optlen))
-		goto out;
+	opt->optlen = len;
 
 	val = test_bit(X25_Q_BIT_FLAG, &x25_sk(sk)->flags);
-	rc = copy_to_user(optval, &val, len) ? -EFAULT : 0;
+	rc = copy_to_iter(&val, len, &opt->iter_out) != len ? -EFAULT : 0;
 out:
 	return rc;
 }
@@ -1753,7 +1749,7 @@ static const struct proto_ops x25_proto_ops = {
 	.listen =	x25_listen,
 	.shutdown =	sock_no_shutdown,
 	.setsockopt =	x25_setsockopt,
-	.getsockopt =	x25_getsockopt,
+	.getsockopt_iter = x25_getsockopt,
 	.sendmsg =	x25_sendmsg,
 	.recvmsg =	x25_recvmsg,
 	.mmap =		sock_no_mmap,