From: Shyam Prasad N <sprasad@microsoft.com>
Date: Thu, 14 Oct 2021 11:52:39 +0000
Subject: [PATCH] cifs: To match file servers, make sure the server hostname
 matches
Git-commit: 7be3248f313930ff3d3436d4e9ddbe9fccc1f541
Patch-mainline: v5.16-rc1
References: bsc#1192606

We generally rely on a bunch of factors to differentiate between servers.
For example, IP address, port etc.

For certain server types (like Azure), it is important to make sure
that the server hostname matches too, even if the both hostnames currently
resolve to the same IP address.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Enzo Matsumiya <ematsumiya@suse.de>
---
 fs/cifs/connect.c    |   19 +++++++++++--------
 fs/cifs/fs_context.c |    8 ++++++++
 fs/cifs/fs_context.h |    1 +
 3 files changed, 20 insertions(+), 8 deletions(-)

--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -794,7 +794,6 @@ static void clean_demultiplex_info(struc
 		 */
 	}
 
-	kfree(server->hostname);
 	kfree(server);
 
 	length = atomic_dec_return(&tcpSesAllocCount);
@@ -1235,6 +1234,9 @@ static int match_server(struct TCP_Serve
 	if (!net_eq(cifs_net_ns(server), current->nsproxy->net_ns))
 		return 0;
 
+	if (strcasecmp(server->hostname, ctx->server_hostname))
+		return 0;
+
 	if (!match_address(server, addr,
 			   (struct sockaddr *)&ctx->srcaddr))
 		return 0;
@@ -1336,6 +1338,7 @@ cifs_put_tcp_session(struct TCP_Server_I
 	kfree(server->session_key.response);
 	server->session_key.response = NULL;
 	server->session_key.len = 0;
+	kfree(server->hostname);
 
 	task = xchg(&server->tsk, NULL);
 	if (task)
@@ -1361,14 +1364,15 @@ cifs_get_tcp_session(struct smb3_fs_cont
 		goto out_err;
 	}
 
+	tcp_ses->hostname = kstrdup(ctx->server_hostname, GFP_KERNEL);
+	if (!tcp_ses->hostname) {
+		rc = -ENOMEM;
+		goto out_err;
+	}
+
 	tcp_ses->ops = ctx->ops;
 	tcp_ses->vals = ctx->vals;
 	cifs_set_net_ns(tcp_ses, get_net(current->nsproxy->net_ns));
-	tcp_ses->hostname = extract_hostname(ctx->UNC);
-	if (IS_ERR(tcp_ses->hostname)) {
-		rc = PTR_ERR(tcp_ses->hostname);
-		goto out_err_crypto_release;
-	}
 
 	tcp_ses->conn_id = atomic_inc_return(&tcpSesNextId);
 	tcp_ses->noblocksnd = ctx->noblocksnd;
@@ -1496,8 +1500,7 @@ out_err_crypto_release:
 
 out_err:
 	if (tcp_ses) {
-		if (!IS_ERR(tcp_ses->hostname))
-			kfree(tcp_ses->hostname);
+		kfree(tcp_ses->hostname);
 		if (tcp_ses->ssocket)
 			sock_release(tcp_ses->ssocket);
 		kfree(tcp_ses);
--- a/fs/cifs/fs_context.c
+++ b/fs/cifs/fs_context.c
@@ -324,6 +324,7 @@ smb3_fs_context_dup(struct smb3_fs_conte
 	DUP_CTX_STR(mount_options);
 	DUP_CTX_STR(username);
 	DUP_CTX_STR(password);
+	DUP_CTX_STR(server_hostname);
 	DUP_CTX_STR(UNC);
 	DUP_CTX_STR(source);
 	DUP_CTX_STR(domainname);
@@ -462,6 +463,11 @@ smb3_parse_devname(const char *devname,
 	if (!pos)
 		return -EINVAL;
 
+	/* record the server hostname */
+	ctx->server_hostname = kstrndup(devname + 2, pos - devname - 2, GFP_KERNEL);
+	if (!ctx->server_hostname)
+		return -ENOMEM;
+
 	/* skip past delimiter */
 	++pos;
 
@@ -1502,6 +1508,8 @@ smb3_cleanup_fs_context_contents(struct
 	ctx->username = NULL;
 	kzfree(ctx->password);
 	ctx->password = NULL;
+	kfree(ctx->server_hostname);
+	ctx->server_hostname = NULL;
 	kfree(ctx->UNC);
 	ctx->UNC = NULL;
 	kfree(ctx->source);
--- a/fs/cifs/fs_context.h
+++ b/fs/cifs/fs_context.h
@@ -166,6 +166,7 @@ struct smb3_fs_context {
 	char *password;
 	char *domainname;
 	char *source;
+	char *server_hostname;
 	char *UNC;
 	char *nodename;
 	char *iocharset;  /* local code page for mapping to and from Unicode */