net/9p/fd: support ipv6 for trans=tcp

Allows specifying an IPv6 address when mounting a remote 9p file system.

Signed-off-by: Joshua Murphy <joshuamurphy@posteo.net>
Message-ID: <20250118192122.327-2-joshuamurphy@posteo.net>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>

Author: Joshua Murphy

net/9p/trans_fd.c

@@ -11,6 +11,7 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/in.h>
+#include <linux/in6.h>
 #include <linux/module.h>
 #include <linux/net.h>
 #include <linux/ipv6.h>
@@ -954,64 +955,55 @@ static void p9_fd_close(struct p9_client *client)
 	kfree(ts);
 }
 
-/*
- * stolen from NFS - maybe should be made a generic function?
- */
-static inline int valid_ipaddr4(const char *buf)
-{
-	int rc, count, in[4];
-
-	rc = sscanf(buf, "%d.%d.%d.%d", &in[0], &in[1], &in[2], &in[3]);
-	if (rc != 4)
-		return -EINVAL;
-	for (count = 0; count < 4; count++) {
-		if (in[count] > 255)
-			return -EINVAL;
-	}
-	return 0;
-}
-
 static int p9_bind_privport(struct socket *sock)
 {
-	struct sockaddr_in cl;
+	struct sockaddr_storage stor = { 0 };
 	int port, err = -EINVAL;
 
-	memset(&cl, 0, sizeof(cl));
-	cl.sin_family = AF_INET;
-	cl.sin_addr.s_addr = htonl(INADDR_ANY);
+	stor.ss_family = sock->ops->family;
+	if (stor.ss_family == AF_INET)
+		((struct sockaddr_in *)&stor)->sin_addr.s_addr = htonl(INADDR_ANY);
+	else
+		((struct sockaddr_in6 *)&stor)->sin6_addr = in6addr_any;
 	for (port = p9_ipport_resv_max; port >= p9_ipport_resv_min; port--) {
-		cl.sin_port = htons((ushort)port);
-		err = kernel_bind(sock, (struct sockaddr *)&cl, sizeof(cl));
+		if (stor.ss_family == AF_INET)
+			((struct sockaddr_in *)&stor)->sin_port = htons((ushort)port);
+		else
+			((struct sockaddr_in6 *)&stor)->sin6_port = htons((ushort)port);
+		err = kernel_bind(sock, (struct sockaddr *)&stor, sizeof(stor));
 		if (err != -EADDRINUSE)
 			break;
 	}
 	return err;
 }
 
-
 static int
 p9_fd_create_tcp(struct p9_client *client, const char *addr, char *args)
 {
 	int err;
+	char port_str[6];
 	struct socket *csocket;
-	struct sockaddr_in sin_server;
+	struct sockaddr_storage stor = { 0 };
 	struct p9_fd_opts opts;
 
 	err = parse_opts(args, &opts);
 	if (err < 0)
 		return err;
 
-	if (addr == NULL || valid_ipaddr4(addr) < 0)
+	if (!addr)
 		return -EINVAL;
 
+	sprintf(port_str, "%u", opts.port);
+	err = inet_pton_with_scope(current->nsproxy->net_ns, AF_UNSPEC, addr,
+				   port_str, &stor);
+	if (err < 0)
+		return err;
+
 	csocket = NULL;
 
 	client->trans_opts.tcp.port = opts.port;
 	client->trans_opts.tcp.privport = opts.privport;
-	sin_server.sin_family = AF_INET;
-	sin_server.sin_addr.s_addr = in_aton(addr);
-	sin_server.sin_port = htons(opts.port);
-	err = __sock_create(current->nsproxy->net_ns, PF_INET,
+	err = __sock_create(current->nsproxy->net_ns, stor.ss_family,
 			    SOCK_STREAM, IPPROTO_TCP, &csocket, 1);
 	if (err) {
 		pr_err("%s (%d): problem creating socket\n",
@@ -1030,8 +1022,8 @@ p9_fd_create_tcp(struct p9_client *client, const char *addr, char *args)
 	}
 
 	err = READ_ONCE(csocket->ops)->connect(csocket,
-				    (struct sockaddr *)&sin_server,
-				    sizeof(struct sockaddr_in), 0);
+					       (struct sockaddr *)&stor,
+					       sizeof(stor), 0);
 	if (err < 0) {
 		pr_err("%s (%d): problem connecting socket to %s\n",
 		       __func__, task_pid_nr(current), addr);