From cfda35d98298131bf38fbad3ce4cd5ecb3cf18db Mon Sep 17 00:00:00 2001 From: Stefan Metzmacher Date: Tue, 3 May 2016 10:52:30 +0200 Subject: [PATCH] fs/cifs: correctly to anonymous authentication via NTLMSSP See [MS-NLMP] 3.2.5.1.2 Server Receives an AUTHENTICATE_MESSAGE from the Client: ... Set NullSession to FALSE If (AUTHENTICATE_MESSAGE.UserNameLen == 0 AND AUTHENTICATE_MESSAGE.NtChallengeResponse.Length == 0 AND (AUTHENTICATE_MESSAGE.LmChallengeResponse == Z(1) OR AUTHENTICATE_MESSAGE.LmChallengeResponse.Length == 0)) -- Special case: client requested anonymous authentication Set NullSession to TRUE ... Only server which map unknown users to guest will allow access using a non-null NTChallengeResponse. For Samba it's the "map to guest = bad user" option. BUG: https://bugzilla.samba.org/show_bug.cgi?id=11913 CC: Stable Signed-off-by: Stefan Metzmacher Signed-off-by: Steve French --- fs/cifs/sess.c | 32 ++++++++++++++++++++------------ 1 file changed, 20 insertions(+), 12 deletions(-) diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c index 59727e32ed0f..09b0201d15d0 100644 --- a/fs/cifs/sess.c +++ b/fs/cifs/sess.c @@ -400,19 +400,27 @@ int build_ntlmssp_auth_blob(unsigned char *pbuffer, sec_blob->LmChallengeResponse.MaximumLength = 0; sec_blob->NtChallengeResponse.BufferOffset = cpu_to_le32(tmp - pbuffer); - rc = setup_ntlmv2_rsp(ses, nls_cp); - if (rc) { - cifs_dbg(VFS, "Error %d during NTLMSSP authentication\n", rc); - goto setup_ntlmv2_ret; - } - memcpy(tmp, ses->auth_key.response + CIFS_SESS_KEY_SIZE, - ses->auth_key.len - CIFS_SESS_KEY_SIZE); - tmp += ses->auth_key.len - CIFS_SESS_KEY_SIZE; + if (ses->user_name != NULL) { + rc = setup_ntlmv2_rsp(ses, nls_cp); + if (rc) { + cifs_dbg(VFS, "Error %d during NTLMSSP authentication\n", rc); + goto setup_ntlmv2_ret; + } + memcpy(tmp, ses->auth_key.response + CIFS_SESS_KEY_SIZE, + ses->auth_key.len - CIFS_SESS_KEY_SIZE); + tmp += ses->auth_key.len - CIFS_SESS_KEY_SIZE; - sec_blob->NtChallengeResponse.Length = - cpu_to_le16(ses->auth_key.len - CIFS_SESS_KEY_SIZE); - sec_blob->NtChallengeResponse.MaximumLength = - cpu_to_le16(ses->auth_key.len - CIFS_SESS_KEY_SIZE); + sec_blob->NtChallengeResponse.Length = + cpu_to_le16(ses->auth_key.len - CIFS_SESS_KEY_SIZE); + sec_blob->NtChallengeResponse.MaximumLength = + cpu_to_le16(ses->auth_key.len - CIFS_SESS_KEY_SIZE); + } else { + /* + * don't send an NT Response for anonymous access + */ + sec_blob->NtChallengeResponse.Length = 0; + sec_blob->NtChallengeResponse.MaximumLength = 0; + } if (ses->domainName == NULL) { sec_blob->DomainName.BufferOffset = cpu_to_le32(tmp - pbuffer);