On Tue, Oct 19, 2021 at 4:35 PM Namjae Jeon <linkinjeon@xxxxxxxxxx> wrote:
>
> 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.
ok
> > 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 ?
Good catch, auth_msg_off is completely wrong here.
> > + 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
> >
> >
