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ksmbd: use the session dialect for rejected binding signatures

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When an SMB3 session is referenced by a binding request on an SMB2.1
connection, the request is signed with the existing session's SMB3 signing
algorithm. ksmbd instead verifies it with the new connection's SMB2.1 HMAC
algorithm, so verification fails and the client receives
STATUS_ACCESS_DENIED instead of STATUS_REQUEST_NOT_ACCEPTED.

Select the signing verifier from the referenced session dialect. Permit a
signed SESSION_SETUP without an established channel to use the SMB3 session
signing key for verification. This is limited to SESSION_SETUP so other
unbound requests remain rejected.

The rejected response must use the same existing session algorithm. When an
SMB3 session is referenced on an SMB2.1 connection, sign the SESSION_SETUP
response with the SMB3 signing path rather than the connection's SMB2.1
path.

This fixes smb2.session.bind_negative_smb3to2s.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Namjae Jeon
2026-07-02 21:16:50 +09:00
committed by Steve French
parent 3e67423336
commit f49bca41c1
2 changed files with 21 additions and 5 deletions
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10
fs/smb/server/server.c
View File

@@ -243,8 +243,14 @@ static void __handle_ksmbd_work(struct ksmbd_work *work,
if (work->sess &&
(work->sess->sign || smb3_11_final_sess_setup_resp(work) ||
conn->ops->is_sign_req(work, command)))
conn->ops->set_sign_rsp(work);
conn->ops->is_sign_req(work, command))) {
if (command == SMB2_SESSION_SETUP_HE &&
work->sess->dialect >= SMB30_PROT_ID &&
conn->dialect < SMB30_PROT_ID)
smb3_set_sign_rsp(work);
else
conn->ops->set_sign_rsp(work);
}
} while (is_chained == true);
send:

16
fs/smb/server/smb2pdu.c
View File

@@ -2015,10 +2015,16 @@ int smb2_sess_setup(struct ksmbd_work *work)
(req->Flags & SMB2_SESSION_REQ_FLAG_BINDING)) {
sess = ksmbd_session_lookup_slowpath(le64_to_cpu(req->hdr.SessionId));
if (sess) {
int sign_ret;
work->sess = sess;
if (sess->dialect >= SMB30_PROT_ID)
sign_ret = smb3_check_sign_req(work);
else
sign_ret = smb2_check_sign_req(work);
if (sess->state != SMB2_SESSION_VALID ||
!(req->hdr.Flags & SMB2_FLAGS_SIGNED) ||
!conn->ops->check_sign_req(work)) {
!sign_ret) {
ksmbd_user_session_put(sess);
work->sess = NULL;
sess = NULL;
@@ -9681,9 +9687,13 @@ int smb3_check_sign_req(struct ksmbd_work *work)
} else {
chann = lookup_chann_list(work->sess, conn);
if (!chann) {
return 0;
if (le16_to_cpu(hdr->Command) != SMB2_SESSION_SETUP_HE ||
!(hdr->Flags & SMB2_FLAGS_SIGNED))
return 0;
signing_key = work->sess->smb3signingkey;
} else {
signing_key = chann->smb3signingkey;
}
signing_key = chann->smb3signingkey;
}
if (!signing_key) {