projects/linux·commit f49bca41

ksmbd: use the session dialect for rejected binding signatures

f49bca41 · Namjae Jeon <[email protected]> · 2026-07-02 21:16:50 +09:00

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 <[email protected]>
Signed-off-by: Steve French <[email protected]>
Commit
f49bca41c12f9f79d39dbf0779d0c672d74b09fe
Parents
3e674233

Changes

2 files changed · +21 −5

FileStatusAddDelContent
fs/smb/server/server.cmodified+8−2View file
fs/smb/server/smb2pdu.cmodified+13−3View file

fs/smb/server/server.c

View file
diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c
index bc861ca..f5baba9 100644
--- a/fs/smb/server/server.c
+++ b/fs/smb/server/server.c
@@ -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:

fs/smb/server/smb2pdu.c

View file
diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index 123ba63..b731677 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -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) {