[SCTP]: Add check for hmac_algo parameter in sctp_verify_param()

RFC 4890 has the following text:

  The HMAC algorithm based on SHA-1 MUST be supported and
  included in the HMAC-ALGO parameter.

As a result, we need to check in sctp_verify_param() that HMAC_SHA1 is
present in the list.  If not, we should probably treat this as a
protocol violation.

It should also be a protocol violation if the HMAC parameter is empty.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 26 insertions, 3 deletions

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index 578630e8e00d..36ebb392472e 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -1982,7 +1982,10 @@ static sctp_ierror_t sctp_verify_param(const struct sctp_association *asoc,
                                         struct sctp_chunk *chunk,
                                         struct sctp_chunk **err_chunk)
 {
+        struct sctp_hmac_algo_param *hmacs;
         int retval = SCTP_IERROR_NO_ERROR;
+        __u16 n_elt, id = 0;
+        int i;
 
         /* FIXME - This routine is not looking at each parameter per the
          * chunk type, i.e., unrecognized parameters should be further
@@ -2056,9 +2059,29 @@ static sctp_ierror_t sctp_verify_param(const struct sctp_association *asoc,
                 break;
 
         case SCTP_PARAM_HMAC_ALGO:
-                if (sctp_auth_enable)
-                        break;
-                /* Fall Through */
+                if (!sctp_auth_enable)
+                        goto fallthrough;
+
+                hmacs = (struct sctp_hmac_algo_param *)param.p;
+                n_elt = (ntohs(param.p->length) - sizeof(sctp_paramhdr_t)) >> 1;
+
+                /* SCTP-AUTH: Section 6.1
+                 * The HMAC algorithm based on SHA-1 MUST be supported and
+                 * included in the HMAC-ALGO parameter.
+                 */
+                for (i = 0; i < n_elt; i++) {
+                        id = ntohs(hmacs->hmac_ids[i]);
+
+                        if (id == SCTP_AUTH_HMAC_ID_SHA1)
+                                break;
+                }
+
+                if (id != SCTP_AUTH_HMAC_ID_SHA1) {
+                        sctp_process_inv_paramlength(asoc, param.p, chunk,
+                                                     err_chunk);
+                        retval = SCTP_IERROR_ABORT;
+                }
+                break;
 fallthrough:
         default:
                 SCTP_DEBUG_PRINTK("Unrecognized param: %d for chunk %d.\n",