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authorSteve French2019-03-22 22:31:17 -0500
committerSteve French2019-03-22 22:42:49 -0500
commit8c11a607d1d9cd6e7f01fd6b03923597fb0ef95a (patch)
tree36bf4f8f48560f48a482976fe0c70dec9f5d057f
parent68ddb496800acdb46172b4981dc3753ea9b39c25 (diff)
SMB3: Fix SMB3.1.1 guest mounts to Samba
Workaround problem with Samba responses to SMB3.1.1 null user (guest) mounts. The server doesn't set the expected flag in the session setup response so we have to do a similar check to what is done in smb3_validate_negotiate where we also check if the user is a null user (but not sec=krb5 since username might not be passed in on mount for Kerberos case). Note that the commit below tightened the conditions and forced signing for the SMB2-TreeConnect commands as per MS-SMB2. However, this should only apply to normal user sessions and not for cases where there is no user (even if server forgets to set the flag in the response) since we don't have anything useful to sign with. This is especially important now that the more secure SMB3.1.1 protocol is in the default dialect list. An earlier patch ("cifs: allow guest mounts to work for smb3.11") fixed the guest mounts to Windows. Fixes: 6188f28bf608 ("Tree connect for SMB3.1.1 must be signed for non-encrypted shares") Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Paulo Alcantara <palcantara@suse.de> CC: Stable <stable@vger.kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
-rw-r--r--fs/cifs/smb2pdu.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 8e4a1da95418..21ac19ff19cb 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -1631,10 +1631,13 @@ SMB2_tcon(const unsigned int xid, struct cifs_ses *ses, const char *tree,
/*
* 3.11 tcon req must be signed if not encrypted. See MS-SMB2 3.2.4.1.1
* unless it is guest or anonymous user. See MS-SMB2 3.2.5.3.1
+ * (Samba servers don't always set the flag so also check if null user)
*/
if ((ses->server->dialect == SMB311_PROT_ID) &&
!smb3_encryption_required(tcon) &&
- !(ses->session_flags & (SMB2_SESSION_FLAG_IS_GUEST|SMB2_SESSION_FLAG_IS_NULL)))
+ !(ses->session_flags &
+ (SMB2_SESSION_FLAG_IS_GUEST|SMB2_SESSION_FLAG_IS_NULL)) &&
+ ((ses->user_name != NULL) || (ses->sectype == Kerberos)))
req->sync_hdr.Flags |= SMB2_FLAGS_SIGNED;
memset(&rqst, 0, sizeof(struct smb_rqst));