[PATCH 5.15.y 09/11] ksmbd: validate mech token in session setup

Namjae Jeon
2024-01-21T14:31:33Z

[ Upstream commit 92e470163d96df8db6c4fa0f484e4a229edb903d ]

If client send invalid mech token in session setup request, ksmbd
validate and make the error if it is invalid.

Cc: stable@vger.kernel.org
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-22890
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
---
fs/ksmbd/asn1.c | 5 +++++
fs/ksmbd/connection.h | 1 +
fs/ksmbd/smb2pdu.c | 22 +++++++++++++++++-----
3 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/fs/ksmbd/asn1.c b/fs/ksmbd/asn1.c
index 4a4b2b03ff33..b931a99ab9c8 100644
--- a/fs/ksmbd/asn1.c
+++ b/fs/ksmbd/asn1.c
@@ -214,10 +214,15 @@ static int ksmbd_neg_token_alloc(void *context, size_t hdrlen,
{
struct ksmbd_conn *conn = context;

+ if (!vlen)
+ return -EINVAL;
+
conn->mechToken = kmemdup_nul(value, vlen, GFP_KERNEL);
if (!conn->mechToken)
return -ENOMEM;

+ conn->mechTokenLen = (unsigned int)vlen;
+
return 0;
}

diff --git a/fs/ksmbd/connection.h b/fs/ksmbd/connection.h
index 3c005246a32e..342f935f5770 100644
--- a/fs/ksmbd/connection.h
+++ b/fs/ksmbd/connection.h
@@ -88,6 +88,7 @@ struct ksmbd_conn {
__u16 dialect;

char *mechToken;
+ unsigned int mechTokenLen;

struct ksmbd_conn_ops *conn_ops;

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 795d3554abe2..7e8f1c89124f 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -1414,7 +1414,10 @@ static struct ksmbd_user *session_user(struct ksmbd_conn *conn,
char *name;
unsigned int name_off, name_len, secbuf_len;

- secbuf_len = le16_to_cpu(req->SecurityBufferLength);
+ if (conn->use_spnego && conn->mechToken)
+ secbuf_len = conn->mechTokenLen;
+ else
+ secbuf_len = le16_to_cpu(req->SecurityBufferLength);
if (secbuf_len < sizeof(struct authenticate_message)) {
ksmbd_debug(SMB, "blob len %d too small\n", secbuf_len);
return NULL;
@@ -1505,7 +1508,10 @@ static int ntlm_authenticate(struct ksmbd_work *work,
struct authenticate_message *authblob;

authblob = user_authblob(conn, req);
- sz = le16_to_cpu(req->SecurityBufferLength);
+ if (conn->use_spnego && conn->mechToken)
+ sz = conn->mechTokenLen;
+ else
+ sz = le16_to_cpu(req->SecurityBufferLength);
rc = ksmbd_decode_ntlmssp_auth_blob(authblob, sz, conn, sess);
if (rc) {
set_user_flag(sess->user, KSMBD_USER_FLAG_BAD_PASSWORD);
@@ -1778,8 +1784,7 @@ int smb2_sess_setup(struct ksmbd_work *work)

negblob_off = le16_to_cpu(req->SecurityBufferOffset);
negblob_len = le16_to_cpu(req->SecurityBufferLength);
- if (negblob_off < offsetof(struct smb2_sess_setup_req, Buffer) ||
- negblob_len < offsetof(struct negotiate_message, NegotiateFlags)) {
+ if (negblob_off < offsetof(struct smb2_sess_setup_req, Buffer)) {
rc = -EINVAL;
goto out_err;
}
@@ -1788,8 +1793,15 @@ int smb2_sess_setup(struct ksmbd_work *work)
negblob_off);

if (decode_negotiation_token(conn, negblob, negblob_len) == 0) {
- if (conn->mechToken)
+ if (conn->mechToken) {
negblob = (struct negotiate_message *)conn->mechToken;
+ negblob_len = conn->mechTokenLen;
+ }
+ }
+
+ if (negblob_len < offsetof(struct negotiate_message, NegotiateFlags)) {
+ rc = -EINVAL;
+ goto out_err;
}

if (server_conf.auth_mechs & conn->auth_mechs) {
--
2.25.1