Allocate and deallocate memory for encryption contexts within cryptos…

…oft,

rather than requiring each algorithm to provide their own memory handling.
This matches the interface already provided by cryptosoft for
authentication algorithms and removes the need for zerokey functions.

ok mikeb@

sys/crypto/cryptosoft.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: cryptosoft.c,v 1.68 2012/12/11 14:49:31 mikeb Exp $	*/
+/*	$OpenBSD: cryptosoft.c,v 1.69 2013/08/25 14:26:56 jsing Exp $	*/
 
 /*
  * The author of this code is Angelos D. Keromytis (angelos@cis.upenn.edu)
@@ -824,7 +824,15 @@ swcr_newsession(u_int32_t *sid, struct cryptoini *cri)
 			txf = &enc_xform_null;
 			goto enccommon;
 		enccommon:
-			if (txf->setkey(&((*swd)->sw_kschedule), cri->cri_key,
+			if (txf->ctxsize > 0) {
+				(*swd)->sw_kschedule = malloc(txf->ctxsize,
+				    M_CRYPTO_DATA, M_NOWAIT | M_ZERO);
+				if ((*swd)->sw_kschedule == NULL) {
+					swcr_freesession(i);
+					return EINVAL;
+				}
+			}
+			if (txf->setkey((*swd)->sw_kschedule, cri->cri_key,
 			    cri->cri_klen / 8) < 0) {
 				swcr_freesession(i);
 				return EINVAL;
@@ -1013,8 +1021,10 @@ swcr_freesession(u_int64_t tid)
 		case CRYPTO_NULL:
 			txf = swd->sw_exf;
 
-			if (swd->sw_kschedule)
-				txf->zerokey(&(swd->sw_kschedule));
+			if (swd->sw_kschedule) {
+				explicit_bzero(swd->sw_kschedule, txf->ctxsize);
+				free(swd->sw_kschedule, M_CRYPTO_DATA);
+			}
 			break;
 
 		case CRYPTO_MD5_HMAC: