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
References: bsc#1190317
Patch-mainline: v5.16-rc1

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: Paulo Alcantara <palcantara@suse.de>
---
 fs/cifs/cifsglob.h |    1 +
 fs/cifs/connect.c  |   23 +++++++++++++++--------
 2 files changed, 16 insertions(+), 8 deletions(-)

--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -545,6 +545,7 @@ struct smb_version_values {
 struct smb_vol {
 	char *username;
 	char *password;
+	char *server_hostname;
 	char *domainname;
 	char *UNC;
 	char *iocharset;  /* local code page for mapping to and from Unicode */
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1041,7 +1041,6 @@ static void clean_demultiplex_info(struc
 		 */
 	}
 
-	kfree(server->hostname);
 	kfree(server);
 
 	length = atomic_dec_return(&tcpSesAllocCount);
@@ -1584,6 +1583,10 @@ cifs_parse_devname(const char *devname,
 	if (!pos)
 		return -EINVAL;
 
+	vol->server_hostname = kstrndup(devname + 2, pos - devname - 2, GFP_KERNEL);
+	if (!vol->server_hostname)
+		return -ENOMEM;
+
 	/* skip past delimiter */
 	++pos;
 
@@ -2672,6 +2675,9 @@ static int match_server(struct TCP_Serve
 	if (!net_eq(cifs_net_ns(server), current->nsproxy->net_ns))
 		return 0;
 
+	if (strcasecmp(server->hostname, vol->server_hostname))
+		return 0;
+
 	if (!match_address(server, addr,
 			   (struct sockaddr *)&vol->srcaddr))
 		return 0;
@@ -2769,6 +2775,7 @@ 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)
@@ -2794,14 +2801,15 @@ cifs_get_tcp_session(struct smb_vol *vol
 		goto out_err;
 	}
 
+	tcp_ses->hostname = kstrdup(volume_info->server_hostname, GFP_KERNEL);
+	if (!tcp_ses->hostname) {
+		rc = -ENOMEM;
+		goto out_err;
+	}
+
 	tcp_ses->ops = volume_info->ops;
 	tcp_ses->vals = volume_info->vals;
 	cifs_set_net_ns(tcp_ses, get_net(current->nsproxy->net_ns));
-	tcp_ses->hostname = extract_hostname(volume_info->UNC);
-	if (IS_ERR(tcp_ses->hostname)) {
-		rc = PTR_ERR(tcp_ses->hostname);
-		goto out_err_crypto_release;
-	}
 
 	tcp_ses->noblocksnd = volume_info->noblocksnd;
 	tcp_ses->noautotune = volume_info->noautotune;
@@ -2919,8 +2927,7 @@ 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);