2021-10-19 17:36 GMT+09:00, Marios Makassikis <mmakassikis@xxxxxxxxxx>:
> Make sure the security buffer's length/offset are valid with regards to
> the packet length.
>
> Signed-off-by: Marios Makassikis <mmakassikis@xxxxxxxxxx>
> ---
> Changes since v2:
> - check that negblob in smb2_sess_setup() is large enough to access the
> MessageType field
>
> fs/ksmbd/auth.c | 18 ++++++++++------
> fs/ksmbd/smb2pdu.c | 51 ++++++++++++++++++++++++++++------------------
> 2 files changed, 43 insertions(+), 26 deletions(-)
>
> diff --git a/fs/ksmbd/auth.c b/fs/ksmbd/auth.c
> index 71c989f1568d..c9d32fea5669 100644
> --- a/fs/ksmbd/auth.c
> +++ b/fs/ksmbd/auth.c
> @@ -298,8 +298,9 @@ int ksmbd_decode_ntlmssp_auth_blob(struct
> authenticate_message *authblob,
> int blob_len, struct ksmbd_session *sess)
> {
> char *domain_name;
> - unsigned int lm_off, nt_off;
> - unsigned short nt_len;
> + uintptr_t auth_msg_off;
> + unsigned int lm_off, nt_off, dn_off;
> + unsigned short nt_len, dn_len;
> int ret;
>
> if (blob_len < sizeof(struct authenticate_message)) {
> @@ -314,15 +315,20 @@ int ksmbd_decode_ntlmssp_auth_blob(struct
> authenticate_message *authblob,
> return -EINVAL;
> }
>
> + auth_msg_off = (uintptr_t)((char *)authblob + blob_len);
> lm_off = le32_to_cpu(authblob->LmChallengeResponse.BufferOffset);
Let's remove unused lm_off.
> nt_off = le32_to_cpu(authblob->NtChallengeResponse.BufferOffset);
> nt_len = le16_to_cpu(authblob->NtChallengeResponse.Length);
> + dn_off = le32_to_cpu(authblob->DomainName.BufferOffset);
> + dn_len = le16_to_cpu(authblob->DomainName.Length);
> +
> + if (auth_msg_off < (u64)dn_off + dn_len ||
It should be blob_len instead of auth_msg_off ?
> + auth_msg_off < (u64)nt_off + nt_len)
> + return -EINVAL;
>
> /* TODO : use domain name that imported from configuration file */
> - domain_name = smb_strndup_from_utf16((const char *)authblob +
> - le32_to_cpu(authblob->DomainName.BufferOffset),
> - le16_to_cpu(authblob->DomainName.Length), true,
> - sess->conn->local_nls);
> + domain_name = smb_strndup_from_utf16((const char *)authblob + dn_off,
> + dn_len, true, sess->conn->local_nls);
> if (IS_ERR(domain_name))
> return PTR_ERR(domain_name);
>
> diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
> index 005aa93a49d6..f02766b1e9ce 100644
> --- a/fs/ksmbd/smb2pdu.c
> +++ b/fs/ksmbd/smb2pdu.c
> @@ -1274,19 +1274,13 @@ static int generate_preauth_hash(struct ksmbd_work
> *work)
> return 0;
> }
>
> -static int decode_negotiation_token(struct ksmbd_work *work,
> - struct negotiate_message *negblob)
> +static int decode_negotiation_token(struct ksmbd_conn *conn,
> + struct negotiate_message *negblob,
> + size_t sz)
> {
> - struct ksmbd_conn *conn = work->conn;
> - struct smb2_sess_setup_req *req;
> - int sz;
> -
> if (!conn->use_spnego)
> return -EINVAL;
>
> - req = work->request_buf;
> - sz = le16_to_cpu(req->SecurityBufferLength);
> -
> if (ksmbd_decode_negTokenInit((char *)negblob, sz, conn)) {
> if (ksmbd_decode_negTokenTarg((char *)negblob, sz, conn)) {
> conn->auth_mechs |= KSMBD_AUTH_NTLMSSP;
> @@ -1298,9 +1292,9 @@ static int decode_negotiation_token(struct ksmbd_work
> *work,
> }
>
> static int ntlm_negotiate(struct ksmbd_work *work,
> - struct negotiate_message *negblob)
> + struct negotiate_message *negblob,
> + size_t negblob_len)
> {
> - struct smb2_sess_setup_req *req = work->request_buf;
> struct smb2_sess_setup_rsp *rsp = work->response_buf;
> struct challenge_message *chgblob;
> unsigned char *spnego_blob = NULL;
> @@ -1309,8 +1303,7 @@ static int ntlm_negotiate(struct ksmbd_work *work,
> int sz, rc;
>
> ksmbd_debug(SMB, "negotiate phase\n");
> - sz = le16_to_cpu(req->SecurityBufferLength);
> - rc = ksmbd_decode_ntlmssp_neg_blob(negblob, sz, work->sess);
> + rc = ksmbd_decode_ntlmssp_neg_blob(negblob, negblob_len, work->sess);
> if (rc)
> return rc;
>
> @@ -1378,12 +1371,23 @@ static struct ksmbd_user *session_user(struct
> ksmbd_conn *conn,
> struct authenticate_message *authblob;
> struct ksmbd_user *user;
> char *name;
> - int sz;
> + unsigned int auth_msg_len, name_off, name_len, secbuf_len;
>
> + 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;
> + }
> authblob = user_authblob(conn, req);
> - sz = le32_to_cpu(authblob->UserName.BufferOffset);
> - name = smb_strndup_from_utf16((const char *)authblob + sz,
> - le16_to_cpu(authblob->UserName.Length),
> + name_off = le32_to_cpu(authblob->UserName.BufferOffset);
> + name_len = le16_to_cpu(authblob->UserName.Length);
> + auth_msg_len = le16_to_cpu(req->SecurityBufferOffset) + secbuf_len;
> +
> + if (auth_msg_len < (u64)name_off + name_len)
> + return NULL;
> +
> + name = smb_strndup_from_utf16((const char *)authblob + name_off,
> + name_len,
> true,
> conn->local_nls);
> if (IS_ERR(name)) {
> @@ -1629,6 +1633,7 @@ int smb2_sess_setup(struct ksmbd_work *work)
> struct smb2_sess_setup_rsp *rsp = work->response_buf;
> struct ksmbd_session *sess;
> struct negotiate_message *negblob;
> + unsigned int negblob_len, negblob_off;
> int rc = 0;
>
> ksmbd_debug(SMB, "Received request for session setup\n");
> @@ -1709,10 +1714,16 @@ int smb2_sess_setup(struct ksmbd_work *work)
> if (sess->state == SMB2_SESSION_EXPIRED)
> sess->state = SMB2_SESSION_IN_PROGRESS;
>
> + negblob_off = le16_to_cpu(req->SecurityBufferOffset);
> + negblob_len = le16_to_cpu(req->SecurityBufferLength);
> + if (negblob_off < (offsetof(struct smb2_sess_setup_req, Buffer) - 4) ||
> + negblob_len < offsetof(struct negotiate_message, NegotiateFlags))
> + return -EINVAL;
> +
> negblob = (struct negotiate_message *)((char *)&req->hdr.ProtocolId +
> - le16_to_cpu(req->SecurityBufferOffset));
> + negblob_off);
>
> - if (decode_negotiation_token(work, negblob) == 0) {
> + if (decode_negotiation_token(conn, negblob, negblob_len) == 0) {
> if (conn->mechToken)
> negblob = (struct negotiate_message *)conn->mechToken;
> }
> @@ -1736,7 +1747,7 @@ int smb2_sess_setup(struct ksmbd_work *work)
> sess->Preauth_HashValue = NULL;
> } else if (conn->preferred_auth_mech == KSMBD_AUTH_NTLMSSP) {
> if (negblob->MessageType == NtLmNegotiate) {
> - rc = ntlm_negotiate(work, negblob);
> + rc = ntlm_negotiate(work, negblob, negblob_len);
> if (rc)
> goto out_err;
> rsp->hdr.Status =
> --
> 2.25.1
>
>
