[PATCH 5.15 156/917] cifs: To match file servers, make sure the server hostname matches

Greg Kroah-Hartman
2021-11-15T23:31:37Z

From: Shyam Prasad N <sprasad@microsoft.com>

commit 7be3248f313930ff3d3436d4e9ddbe9fccc1f541 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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->noblockcnt = ctx->rootfs;
@@ -1497,8 +1501,7 @@ 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
@@ -318,6 +318,7 @@ 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);
@@ -456,6 +457,11 @@ 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;

@@ -1496,6 +1502,8 @@ smb3_cleanup_fs_context_contents(struct
ctx->username = NULL;
kfree_sensitive(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 */