/*
* smb2_sign_check_request
*
* Calculates MAC signature for the request mbuf chain
* using the next expected sequence number and compares
* it to the given signature.
*
* Note it does not check the signature for secondary transactions
* as their sequence number is the same as the original request.
*
* Return 0 if the signature verifies, otherwise, returns -1;
*
*/
int
smb2_sign_check_request(smb_request_t *sr)
{
uint8_t req_sig[SMB2_SIG_SIZE];
uint8_t digest[SHA256_DIGEST_LENGTH];
struct mbuf_chain *mbc = &sr->smb_data;
struct smb_sign *sign = &sr->session->signing;
int sig_off;
/*
* Don't check commands with a zero session ID.
* [MS-SMB2] 3.3.4.1.1
*/
if (sr->smb_uid == 0)
return (0);
/* Get the request signature. */
sig_off = sr->smb2_cmd_hdr + SMB2_SIG_OFFS;
if (smb_mbc_peek(mbc, sig_off, "#c", SMB2_SIG_SIZE, req_sig) != 0)
return (-1);
/* Compute what we think it should be. */
if (smb2_sign_calc(mbc, sign, digest) != 0)
return (-1);
if (memcmp(digest, req_sig, SMB2_SIG_SIZE) != 0) {
cmn_err(CE_NOTE, "smb2_sign_check_request: bad signature");
return (-1);
}
return (0);
}
/*
* smb2_sign_check_request
*
* Calculates MAC signature for the request mbuf chain
* using the next expected sequence number and compares
* it to the given signature.
*
* Note it does not check the signature for secondary transactions
* as their sequence number is the same as the original request.
*
* Return 0 if the signature verifies, otherwise, returns -1;
*
*/
int
smb2_sign_check_request(smb_request_t *sr)
{
uint8_t req_sig[SMB2_SIG_SIZE];
uint8_t vfy_sig[SMB2_SIG_SIZE];
struct mbuf_chain *mbc = &sr->smb_data;
smb_session_t *s = sr->session;
smb_user_t *u = sr->uid_user;
int sig_off;
/*
* Don't check commands with a zero session ID.
* [MS-SMB2] 3.3.4.1.1
*/
if (sr->smb_uid == 0 || u == NULL)
return (0);
/* In case _sign_begin failed. */
if (s->sign_calc == NULL)
return (-1);
/* Get the request signature. */
sig_off = sr->smb2_cmd_hdr + SMB2_SIG_OFFS;
if (smb_mbc_peek(mbc, sig_off, "#c", SMB2_SIG_SIZE, req_sig) != 0)
return (-1);
/*
* Compute the correct signature and compare.
* smb2_sign_calc() or smb3_sign_calc()
*/
if (s->sign_calc(sr, mbc, vfy_sig) != 0)
return (-1);
if (memcmp(vfy_sig, req_sig, SMB2_SIG_SIZE) != 0) {
cmn_err(CE_NOTE, "smb2_sign_check_request: bad signature");
return (-1);
}
return (0);
}
static int
smb2_sign_calc_common(smb_request_t *sr, struct mbuf_chain *mbc,
uint8_t *digest, mac_ops_t *ops)
{
uint8_t tmp_hdr[SMB2_HDR_SIZE];
smb_sign_ctx_t ctx = 0;
smb_session_t *s = sr->session;
smb_user_t *u = sr->uid_user;
struct smb_key *sign_key = &u->u_sign_key;
struct mbuf *mbuf;
int offset, resid, tlen, rc;
if (s->sign_mech == NULL || sign_key->len == 0)
return (-1);
/* smb2_hmac_init or smb3_cmac_init */
rc = ops->mac_init(&ctx, s->sign_mech, sign_key->key, sign_key->len);
if (rc != 0)
return (rc);
/*
* Work with a copy of the SMB2 header so we can
* clear the signature field without modifying
* the original message.
*/
tlen = SMB2_HDR_SIZE;
offset = mbc->chain_offset;
resid = mbc->max_bytes - offset;
if (smb_mbc_peek(mbc, offset, "#c", tlen, tmp_hdr) != 0)
return (-1);
bzero(tmp_hdr + SMB2_SIG_OFFS, SMB2_SIG_SIZE);
/* smb2_hmac_update or smb3_cmac_update */
if ((rc = ops->mac_update(ctx, tmp_hdr, tlen)) != 0)
return (rc);
offset += tlen;
resid -= tlen;
/*
* Digest the rest of the SMB packet, starting at the data
* just after the SMB header.
*
* Advance to the src mbuf where we start digesting.
*/
mbuf = mbc->chain;
while (mbuf != NULL && (offset >= mbuf->m_len)) {
offset -= mbuf->m_len;
mbuf = mbuf->m_next;
}
if (mbuf == NULL)
return (-1);
/*
* Digest the remainder of this mbuf, limited to the
* residual count, and starting at the current offset.
* (typically SMB2_HDR_SIZE)
*/
tlen = mbuf->m_len - offset;
if (tlen > resid)
tlen = resid;
/* smb2_hmac_update or smb3_cmac_update */
rc = ops->mac_update(ctx, (uint8_t *)mbuf->m_data + offset, tlen);
if (rc != 0)
return (rc);
resid -= tlen;
/*
* Digest any more mbufs in the chain.
*/
while (resid > 0) {
mbuf = mbuf->m_next;
if (mbuf == NULL)
return (-1);
tlen = mbuf->m_len;
if (tlen > resid)
tlen = resid;
rc = ops->mac_update(ctx, (uint8_t *)mbuf->m_data, tlen);
if (rc != 0)
return (rc);
resid -= tlen;
}
/*
* smb2_hmac_final or smb3_cmac_final
* Note: digest is _always_ SMB2_SIG_SIZE,
* even if the mech uses a longer one.
*
* smb2_hmac_update or smb3_cmac_update
*/
if ((rc = ops->mac_final(ctx, digest)) != 0)
return (rc);
return (0);
}
/*
* smb2_sign_calc
*
* Calculates MAC signature for the given buffer and returns
* it in the mac_sign parameter.
*
* The sequence number is in the last 16 bytes of the SMB2 header.
* The signature algorighm is to compute HMAC SHA256 over the
* entire command, with the signature field set to zeros.
*
* Return 0 if success else -1
*/
int
smb2_sign_calc(struct mbuf_chain *mbc,
struct smb_sign *sign,
uint8_t *digest)
{
sha2_hc_ctx_t hctx;
uint8_t tmp_hdr[SMB2_HDR_SIZE];
struct mbuf *mbuf;
int offset = mbc->chain_offset;
int resid = mbc->max_bytes - offset;
int tlen;
if (sign->mackey == NULL)
return (-1);
bzero(&hctx, sizeof (hctx));
if (smb2_hmac_sha256_init(&hctx, sign->mackey, sign->mackey_len))
return (-1);
/*
* Work with a copy of the SMB2 header so we can
* clear the signature field without modifying
* the original message.
*/
tlen = SMB2_HDR_SIZE;
if (smb_mbc_peek(mbc, offset, "#c", tlen, tmp_hdr) != 0)
return (-1);
bzero(tmp_hdr + SMB2_SIG_OFFS, SMB2_SIG_SIZE);
smb2_hmac_sha256_update(&hctx, tmp_hdr, tlen);
offset += tlen;
resid -= tlen;
/*
* Digest the rest of the SMB packet, starting at the data
* just after the SMB header.
*
* Advance to the src mbuf where we start digesting.
*/
mbuf = mbc->chain;
while (mbuf != NULL && (offset >= mbuf->m_len)) {
offset -= mbuf->m_len;
mbuf = mbuf->m_next;
}
if (mbuf == NULL)
return (-1);
/*
* Digest the remainder of this mbuf, limited to the
* residual count, and starting at the current offset.
* (typically SMB2_HDR_SIZE)
*/
tlen = mbuf->m_len - offset;
if (tlen > resid)
tlen = resid;
smb2_hmac_sha256_update(&hctx, (uint8_t *)mbuf->m_data + offset, tlen);
resid -= tlen;
/*
* Digest any more mbufs in the chain.
*/
while (resid > 0) {
mbuf = mbuf->m_next;
if (mbuf == NULL)
return (-1);
tlen = mbuf->m_len;
if (tlen > resid)
tlen = resid;
smb2_hmac_sha256_update(&hctx, (uint8_t *)mbuf->m_data, tlen);
resid -= tlen;
}
smb2_hmac_sha256_final(&hctx, digest);
return (0);
}
