5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Namjae Jeon <linkinjeon@xxxxxxxxxx>
[ Upstream commit f9929ef6a2a55f03aac61248c6a3a987b8546f2a ]
When mounting cifs client, can see the following warning message.
CIFS: decode_ntlmssp_challenge: authentication has been weakened as server
does not support key exchange
To remove this warning message, Add support for key exchange feature to
ksmbd. This patch decrypts 16-byte ciphertext value sent by the client
using RC4 with session key. The decrypted value is the recovered secondary
key that will use instead of the session key for signing and sealing.
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ksmbd/auth.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
--- a/fs/ksmbd/auth.c
+++ b/fs/ksmbd/auth.c
@@ -29,6 +29,7 @@
#include "mgmt/user_config.h"
#include "crypto_ctx.h"
#include "transport_ipc.h"
+#include "../smbfs_common/arc4.h"
/*
* Fixed format data defining GSS header and fixed string
@@ -342,6 +343,29 @@ int ksmbd_decode_ntlmssp_auth_blob(struc
nt_len - CIFS_ENCPWD_SIZE,
domain_name, conn->ntlmssp.cryptkey);
kfree(domain_name);
+
+ /* The recovered secondary session key */
+ if (conn->ntlmssp.client_flags & NTLMSSP_NEGOTIATE_KEY_XCH) {
+ struct arc4_ctx *ctx_arc4;
+ unsigned int sess_key_off, sess_key_len;
+
+ sess_key_off = le32_to_cpu(authblob->SessionKey.BufferOffset);
+ sess_key_len = le16_to_cpu(authblob->SessionKey.Length);
+
+ if (blob_len < (u64)sess_key_off + sess_key_len)
+ return -EINVAL;
+
+ ctx_arc4 = kmalloc(sizeof(*ctx_arc4), GFP_KERNEL);
+ if (!ctx_arc4)
+ return -ENOMEM;
+
+ cifs_arc4_setkey(ctx_arc4, sess->sess_key,
+ SMB2_NTLMV2_SESSKEY_SIZE);
+ cifs_arc4_crypt(ctx_arc4, sess->sess_key,
+ (char *)authblob + sess_key_off, sess_key_len);
+ kfree_sensitive(ctx_arc4);
+ }
+
return ret;
}
@@ -414,6 +438,9 @@ ksmbd_build_ntlmssp_challenge_blob(struc
(cflags & NTLMSSP_NEGOTIATE_EXTENDED_SEC))
flags |= NTLMSSP_NEGOTIATE_EXTENDED_SEC;
+ if (cflags & NTLMSSP_NEGOTIATE_KEY_XCH)
+ flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
+
chgblob->NegotiateFlags = cpu_to_le32(flags);
len = strlen(ksmbd_netbios_name());
name = kmalloc(2 + UNICODE_LEN(len), GFP_KERNEL);
