xref: /freebsd-10.1-release/sys/opencrypto/cryptosoft.c

/*	$OpenBSD: cryptosoft.c,v 1.35 2002/04/26 08:43:50 deraadt Exp $	*/

/*-
 * The author of this code is Angelos D. Keromytis (angelos@cis.upenn.edu)
 * Copyright (c) 2002-2006 Sam Leffler, Errno Consulting
 *
 * This code was written by Angelos D. Keromytis in Athens, Greece, in
 * February 2000. Network Security Technologies Inc. (NSTI) kindly
 * supported the development of this code.
 *
 * Copyright (c) 2000, 2001 Angelos D. Keromytis
 *
 * Permission to use, copy, and modify this software with or without fee
 * is hereby granted, provided that this entire notice is included in
 * all source code copies of any software which is or includes a copy or
 * modification of this software.
 *
 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
 * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
 * PURPOSE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: head/sys/opencrypto/cryptosoft.c 184205 2008-10-23 15:53:51Z des $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <sys/sysctl.h>
#include <sys/errno.h>
#include <sys/random.h>
#include <sys/kernel.h>
#include <sys/uio.h>

#include <crypto/blowfish/blowfish.h>
#include <crypto/sha1.h>
#include <opencrypto/rmd160.h>
#include <opencrypto/cast.h>
#include <opencrypto/skipjack.h>
#include <sys/md5.h>

#include <opencrypto/cryptodev.h>
#include <opencrypto/cryptosoft.h>
#include <opencrypto/xform.h>

#include <sys/kobj.h>
#include <sys/bus.h>
#include "cryptodev_if.h"

static	int32_t swcr_id;
static	struct swcr_data **swcr_sessions = NULL;
static	u_int32_t swcr_sesnum;

u_int8_t hmac_ipad_buffer[HMAC_MAX_BLOCK_LEN];
u_int8_t hmac_opad_buffer[HMAC_MAX_BLOCK_LEN];

static	int swcr_encdec(struct cryptodesc *, struct swcr_data *, caddr_t, int);
static	int swcr_authcompute(struct cryptodesc *, struct swcr_data *, caddr_t, int);
static	int swcr_compdec(struct cryptodesc *, struct swcr_data *, caddr_t, int);
static	int swcr_freesession(device_t dev, u_int64_t tid);

/*
 * Apply a symmetric encryption/decryption algorithm.
 */
static int
swcr_encdec(struct cryptodesc *crd, struct swcr_data *sw, caddr_t buf,
    int flags)
{
	unsigned char iv[EALG_MAX_BLOCK_LEN], blk[EALG_MAX_BLOCK_LEN], *idat;
	unsigned char *ivp, piv[EALG_MAX_BLOCK_LEN];
	struct enc_xform *exf;
	int i, k, j, blks;

	exf = sw->sw_exf;
	blks = exf->blocksize;

	/* Check for non-padded data */
	if (crd->crd_len % blks)
		return EINVAL;

	/* Initialize the IV */
	if (crd->crd_flags & CRD_F_ENCRYPT) {
		/* IV explicitly provided ? */
		if (crd->crd_flags & CRD_F_IV_EXPLICIT)
			bcopy(crd->crd_iv, iv, blks);
		else
			arc4rand(iv, blks, 0);

		/* Do we need to write the IV */
		if (!(crd->crd_flags & CRD_F_IV_PRESENT))
			crypto_copyback(flags, buf, crd->crd_inject, blks, iv);

	} else {	/* Decryption */
			/* IV explicitly provided ? */
		if (crd->crd_flags & CRD_F_IV_EXPLICIT)
			bcopy(crd->crd_iv, iv, blks);
		else {
			/* Get IV off buf */
			crypto_copydata(flags, buf, crd->crd_inject, blks, iv);
		}
	}

	if (crd->crd_flags & CRD_F_KEY_EXPLICIT) {
		int error;

		if (sw->sw_kschedule)
			exf->zerokey(&(sw->sw_kschedule));
		error = exf->setkey(&sw->sw_kschedule,
				crd->crd_key, crd->crd_klen / 8);
		if (error)
			return (error);
	}
	ivp = iv;

	if (flags & CRYPTO_F_IMBUF) {
		struct mbuf *m = (struct mbuf *) buf;

		/* Find beginning of data */
		m = m_getptr(m, crd->crd_skip, &k);
		if (m == NULL)
			return EINVAL;

		i = crd->crd_len;

		while (i > 0) {
			/*
			 * If there's insufficient data at the end of
			 * an mbuf, we have to do some copying.
			 */
			if (m->m_len < k + blks && m->m_len != k) {
				m_copydata(m, k, blks, blk);

				/* Actual encryption/decryption */
				if (crd->crd_flags & CRD_F_ENCRYPT) {
					/* XOR with previous block */
					for (j = 0; j < blks; j++)
						blk[j] ^= ivp[j];

					exf->encrypt(sw->sw_kschedule, blk);

					/*
					 * Keep encrypted block for XOR'ing
					 * with next block
					 */
					bcopy(blk, iv, blks);
					ivp = iv;
				} else {	/* decrypt */
					/*
					 * Keep encrypted block for XOR'ing
					 * with next block
					 */
					if (ivp == iv)
						bcopy(blk, piv, blks);
					else
						bcopy(blk, iv, blks);

					exf->decrypt(sw->sw_kschedule, blk);

					/* XOR with previous block */
					for (j = 0; j < blks; j++)
						blk[j] ^= ivp[j];

					if (ivp == iv)
						bcopy(piv, iv, blks);
					else
						ivp = iv;
				}

				/* Copy back decrypted block */
				m_copyback(m, k, blks, blk);

				/* Advance pointer */
				m = m_getptr(m, k + blks, &k);
				if (m == NULL)
					return EINVAL;

				i -= blks;

				/* Could be done... */
				if (i == 0)
					break;
			}

			/* Skip possibly empty mbufs */
			if (k == m->m_len) {
				for (m = m->m_next; m && m->m_len == 0;
				    m = m->m_next)
					;
				k = 0;
			}

			/* Sanity check */
			if (m == NULL)
				return EINVAL;

			/*
			 * Warning: idat may point to garbage here, but
			 * we only use it in the while() loop, only if
			 * there are indeed enough data.
			 */
			idat = mtod(m, unsigned char *) + k;

	   		while (m->m_len >= k + blks && i > 0) {
				if (crd->crd_flags & CRD_F_ENCRYPT) {
					/* XOR with previous block/IV */
					for (j = 0; j < blks; j++)
						idat[j] ^= ivp[j];

					exf->encrypt(sw->sw_kschedule, idat);
					ivp = idat;
				} else {	/* decrypt */
					/*
					 * Keep encrypted block to be used
					 * in next block's processing.
					 */
					if (ivp == iv)
						bcopy(idat, piv, blks);
					else
						bcopy(idat, iv, blks);

					exf->decrypt(sw->sw_kschedule, idat);

					/* XOR with previous block/IV */
					for (j = 0; j < blks; j++)
						idat[j] ^= ivp[j];

					if (ivp == iv)
						bcopy(piv, iv, blks);
					else
						ivp = iv;
				}

				idat += blks;
				k += blks;
				i -= blks;
			}
		}

		return 0; /* Done with mbuf encryption/decryption */
	} else if (flags & CRYPTO_F_IOV) {
		struct uio *uio = (struct uio *) buf;
		struct iovec *iov;

		/* Find beginning of data */
		iov = cuio_getptr(uio, crd->crd_skip, &k);
		if (iov == NULL)
			return EINVAL;

		i = crd->crd_len;

		while (i > 0) {
			/*
			 * If there's insufficient data at the end of
			 * an iovec, we have to do some copying.
			 */
			if (iov->iov_len < k + blks && iov->iov_len != k) {
				cuio_copydata(uio, k, blks, blk);

				/* Actual encryption/decryption */
				if (crd->crd_flags & CRD_F_ENCRYPT) {
					/* XOR with previous block */
					for (j = 0; j < blks; j++)
						blk[j] ^= ivp[j];

					exf->encrypt(sw->sw_kschedule, blk);

					/*
					 * Keep encrypted block for XOR'ing
					 * with next block
					 */
					bcopy(blk, iv, blks);
					ivp = iv;
				} else {	/* decrypt */
					/*
					 * Keep encrypted block for XOR'ing
					 * with next block
					 */
					if (ivp == iv)
						bcopy(blk, piv, blks);
					else
						bcopy(blk, iv, blks);

					exf->decrypt(sw->sw_kschedule, blk);

					/* XOR with previous block */
					for (j = 0; j < blks; j++)
						blk[j] ^= ivp[j];

					if (ivp == iv)
						bcopy(piv, iv, blks);
					else
						ivp = iv;
				}

				/* Copy back decrypted block */
				cuio_copyback(uio, k, blks, blk);

				/* Advance pointer */
				iov = cuio_getptr(uio, k + blks, &k);
				if (iov == NULL)
					return EINVAL;

				i -= blks;

				/* Could be done... */
				if (i == 0)
					break;
			}

			/*
			 * Warning: idat may point to garbage here, but
			 * we only use it in the while() loop, only if
			 * there are indeed enough data.
			 */
			idat = (char *)iov->iov_base + k;

	   		while (iov->iov_len >= k + blks && i > 0) {
				if (crd->crd_flags & CRD_F_ENCRYPT) {
					/* XOR with previous block/IV */
					for (j = 0; j < blks; j++)
						idat[j] ^= ivp[j];

					exf->encrypt(sw->sw_kschedule, idat);
					ivp = idat;
				} else {	/* decrypt */
					/*
					 * Keep encrypted block to be used
					 * in next block's processing.
					 */
					if (ivp == iv)
						bcopy(idat, piv, blks);
					else
						bcopy(idat, iv, blks);

					exf->decrypt(sw->sw_kschedule, idat);

					/* XOR with previous block/IV */
					for (j = 0; j < blks; j++)
						idat[j] ^= ivp[j];

					if (ivp == iv)
						bcopy(piv, iv, blks);
					else
						ivp = iv;
				}

				idat += blks;
				k += blks;
				i -= blks;
			}
		}

		return 0; /* Done with iovec encryption/decryption */
	} else {	/* contiguous buffer */
		if (crd->crd_flags & CRD_F_ENCRYPT) {
			for (i = crd->crd_skip;
			    i < crd->crd_skip + crd->crd_len; i += blks) {
				/* XOR with the IV/previous block, as appropriate. */
				if (i == crd->crd_skip)
					for (k = 0; k < blks; k++)
						buf[i + k] ^= ivp[k];
				else
					for (k = 0; k < blks; k++)
						buf[i + k] ^= buf[i + k - blks];
				exf->encrypt(sw->sw_kschedule, buf + i);
			}
		} else {		/* Decrypt */
			/*
			 * Start at the end, so we don't need to keep the encrypted
			 * block as the IV for the next block.
			 */
			for (i = crd->crd_skip + crd->crd_len - blks;
			    i >= crd->crd_skip; i -= blks) {
				exf->decrypt(sw->sw_kschedule, buf + i);

				/* XOR with the IV/previous block, as appropriate */
				if (i == crd->crd_skip)
					for (k = 0; k < blks; k++)
						buf[i + k] ^= ivp[k];
				else
					for (k = 0; k < blks; k++)
						buf[i + k] ^= buf[i + k - blks];
			}
		}

		return 0; /* Done with contiguous buffer encryption/decryption */
	}

	/* Unreachable */
	return EINVAL;
}

static void
swcr_authprepare(struct auth_hash *axf, struct swcr_data *sw, u_char *key,
    int klen)
{
	int k;

	klen /= 8;

	switch (axf->type) {
	case CRYPTO_MD5_HMAC:
	case CRYPTO_SHA1_HMAC:
	case CRYPTO_SHA2_256_HMAC:
	case CRYPTO_SHA2_384_HMAC:
	case CRYPTO_SHA2_512_HMAC:
	case CRYPTO_NULL_HMAC:
	case CRYPTO_RIPEMD160_HMAC:
		for (k = 0; k < klen; k++)
			key[k] ^= HMAC_IPAD_VAL;

		axf->Init(sw->sw_ictx);
		axf->Update(sw->sw_ictx, key, klen);
		axf->Update(sw->sw_ictx, hmac_ipad_buffer, axf->blocksize - klen);

		for (k = 0; k < klen; k++)
			key[k] ^= (HMAC_IPAD_VAL ^ HMAC_OPAD_VAL);

		axf->Init(sw->sw_octx);
		axf->Update(sw->sw_octx, key, klen);
		axf->Update(sw->sw_octx, hmac_opad_buffer, axf->blocksize - klen);

		for (k = 0; k < klen; k++)
			key[k] ^= HMAC_OPAD_VAL;
		break;
	case CRYPTO_MD5_KPDK:
	case CRYPTO_SHA1_KPDK:
		sw->sw_klen = klen;
		bcopy(key, sw->sw_octx, klen);
		axf->Init(sw->sw_ictx);
		axf->Update(sw->sw_ictx, key, klen);
		axf->Final(NULL, sw->sw_ictx);
		break;
	default:
		printf("%s: CRD_F_KEY_EXPLICIT flag given, but algorithm %d "
		    "doesn't use keys.\n", __func__, axf->type);
	}
}

/*
 * Compute keyed-hash authenticator.
 */
static int
swcr_authcompute(struct cryptodesc *crd, struct swcr_data *sw, caddr_t buf,
    int flags)
{
	unsigned char aalg[HASH_MAX_LEN];
	struct auth_hash *axf;
	union authctx ctx;
	int err;

	if (sw->sw_ictx == 0)
		return EINVAL;

	axf = sw->sw_axf;

	if (crd->crd_flags & CRD_F_KEY_EXPLICIT)
		swcr_authprepare(axf, sw, crd->crd_key, crd->crd_klen);

	bcopy(sw->sw_ictx, &ctx, axf->ctxsize);

	err = crypto_apply(flags, buf, crd->crd_skip, crd->crd_len,
	    (int (*)(void *, void *, unsigned int))axf->Update, (caddr_t)&ctx);
	if (err)
		return err;

	switch (sw->sw_alg) {
	case CRYPTO_MD5_HMAC:
	case CRYPTO_SHA1_HMAC:
	case CRYPTO_SHA2_256_HMAC:
	case CRYPTO_SHA2_384_HMAC:
	case CRYPTO_SHA2_512_HMAC:
	case CRYPTO_RIPEMD160_HMAC:
		if (sw->sw_octx == NULL)
			return EINVAL;

		axf->Final(aalg, &ctx);
		bcopy(sw->sw_octx, &ctx, axf->ctxsize);
		axf->Update(&ctx, aalg, axf->hashsize);
		axf->Final(aalg, &ctx);
		break;

	case CRYPTO_MD5_KPDK:
	case CRYPTO_SHA1_KPDK:
		if (sw->sw_octx == NULL)
			return EINVAL;

		axf->Update(&ctx, sw->sw_octx, sw->sw_klen);
		axf->Final(aalg, &ctx);
		break;

	case CRYPTO_NULL_HMAC:
		axf->Final(aalg, &ctx);
		break;
	}

	/* Inject the authentication data */
	crypto_copyback(flags, buf, crd->crd_inject,
	    sw->sw_mlen == 0 ? axf->hashsize : sw->sw_mlen, aalg);
	return 0;
}

/*
 * Apply a compression/decompression algorithm
 */
static int
swcr_compdec(struct cryptodesc *crd, struct swcr_data *sw,
    caddr_t buf, int flags)
{
	u_int8_t *data, *out;
	struct comp_algo *cxf;
	int adj;
	u_int32_t result;

	cxf = sw->sw_cxf;

	/* We must handle the whole buffer of data in one time
	 * then if there is not all the data in the mbuf, we must
	 * copy in a buffer.
	 */

	data = malloc(crd->crd_len, M_CRYPTO_DATA,  M_NOWAIT);
	if (data == NULL)
		return (EINVAL);
	crypto_copydata(flags, buf, crd->crd_skip, crd->crd_len, data);

	if (crd->crd_flags & CRD_F_COMP)
		result = cxf->compress(data, crd->crd_len, &out);
	else
		result = cxf->decompress(data, crd->crd_len, &out);

	free(data, M_CRYPTO_DATA);
	if (result == 0)
		return EINVAL;

	/* Copy back the (de)compressed data. m_copyback is
	 * extending the mbuf as necessary.
	 */
	sw->sw_size = result;
	/* Check the compressed size when doing compression */
	if (crd->crd_flags & CRD_F_COMP) {
		if (result > crd->crd_len) {
			/* Compression was useless, we lost time */
			free(out, M_CRYPTO_DATA);
			return 0;
		}
	}

	crypto_copyback(flags, buf, crd->crd_skip, result, out);
	if (result < crd->crd_len) {
		adj = result - crd->crd_len;
		if (flags & CRYPTO_F_IMBUF) {
			adj = result - crd->crd_len;
			m_adj((struct mbuf *)buf, adj);
		} else if (flags & CRYPTO_F_IOV) {
			struct uio *uio = (struct uio *)buf;
			int ind;

			adj = crd->crd_len - result;
			ind = uio->uio_iovcnt - 1;

			while (adj > 0 && ind >= 0) {
				if (adj < uio->uio_iov[ind].iov_len) {
					uio->uio_iov[ind].iov_len -= adj;
					break;
				}

				adj -= uio->uio_iov[ind].iov_len;
				uio->uio_iov[ind].iov_len = 0;
				ind--;
				uio->uio_iovcnt--;
			}
		}
	}
	free(out, M_CRYPTO_DATA);
	return 0;
}

/*
 * Generate a new software session.
 */
static int
swcr_newsession(device_t dev, u_int32_t *sid, struct cryptoini *cri)
{
	struct swcr_data **swd;
	struct auth_hash *axf;
	struct enc_xform *txf;
	struct comp_algo *cxf;
	u_int32_t i;
	int error;

	if (sid == NULL || cri == NULL)
		return EINVAL;

	if (swcr_sessions) {
		for (i = 1; i < swcr_sesnum; i++)
			if (swcr_sessions[i] == NULL)
				break;
	} else
		i = 1;		/* NB: to silence compiler warning */

	if (swcr_sessions == NULL || i == swcr_sesnum) {
		if (swcr_sessions == NULL) {
			i = 1; /* We leave swcr_sessions[0] empty */
			swcr_sesnum = CRYPTO_SW_SESSIONS;
		} else
			swcr_sesnum *= 2;

		swd = malloc(swcr_sesnum * sizeof(struct swcr_data *),
		    M_CRYPTO_DATA, M_NOWAIT|M_ZERO);
		if (swd == NULL) {
			/* Reset session number */
			if (swcr_sesnum == CRYPTO_SW_SESSIONS)
				swcr_sesnum = 0;
			else
				swcr_sesnum /= 2;
			return ENOBUFS;
		}

		/* Copy existing sessions */
		if (swcr_sessions != NULL) {
			bcopy(swcr_sessions, swd,
			    (swcr_sesnum / 2) * sizeof(struct swcr_data *));
			free(swcr_sessions, M_CRYPTO_DATA);
		}

		swcr_sessions = swd;
	}

	swd = &swcr_sessions[i];
	*sid = i;

	while (cri) {
		*swd = malloc(sizeof(struct swcr_data),
		    M_CRYPTO_DATA, M_NOWAIT|M_ZERO);
		if (*swd == NULL) {
			swcr_freesession(dev, i);
			return ENOBUFS;
		}

		switch (cri->cri_alg) {
		case CRYPTO_DES_CBC:
			txf = &enc_xform_des;
			goto enccommon;
		case CRYPTO_3DES_CBC:
			txf = &enc_xform_3des;
			goto enccommon;
		case CRYPTO_BLF_CBC:
			txf = &enc_xform_blf;
			goto enccommon;
		case CRYPTO_CAST_CBC:
			txf = &enc_xform_cast5;
			goto enccommon;
		case CRYPTO_SKIPJACK_CBC:
			txf = &enc_xform_skipjack;
			goto enccommon;
		case CRYPTO_RIJNDAEL128_CBC:
			txf = &enc_xform_rijndael128;
			goto enccommon;
		case CRYPTO_CAMELLIA_CBC:
			txf = &enc_xform_camellia;
			goto enccommon;
		case CRYPTO_NULL_CBC:
			txf = &enc_xform_null;
			goto enccommon;
		enccommon:
			if (cri->cri_key != NULL) {
				error = txf->setkey(&((*swd)->sw_kschedule),
				    cri->cri_key, cri->cri_klen / 8);
				if (error) {
					swcr_freesession(dev, i);
					return error;
				}
			}
			(*swd)->sw_exf = txf;
			break;

		case CRYPTO_MD5_HMAC:
			axf = &auth_hash_hmac_md5;
			goto authcommon;
		case CRYPTO_SHA1_HMAC:
			axf = &auth_hash_hmac_sha1;
			goto authcommon;
		case CRYPTO_SHA2_256_HMAC:
			axf = &auth_hash_hmac_sha2_256;
			goto authcommon;
		case CRYPTO_SHA2_384_HMAC:
			axf = &auth_hash_hmac_sha2_384;
			goto authcommon;
		case CRYPTO_SHA2_512_HMAC:
			axf = &auth_hash_hmac_sha2_512;
			goto authcommon;
		case CRYPTO_NULL_HMAC:
			axf = &auth_hash_null;
			goto authcommon;
		case CRYPTO_RIPEMD160_HMAC:
			axf = &auth_hash_hmac_ripemd_160;
		authcommon:
			(*swd)->sw_ictx = malloc(axf->ctxsize, M_CRYPTO_DATA,
			    M_NOWAIT);
			if ((*swd)->sw_ictx == NULL) {
				swcr_freesession(dev, i);
				return ENOBUFS;
			}

			(*swd)->sw_octx = malloc(axf->ctxsize, M_CRYPTO_DATA,
			    M_NOWAIT);
			if ((*swd)->sw_octx == NULL) {
				swcr_freesession(dev, i);
				return ENOBUFS;
			}

			if (cri->cri_key != NULL) {
				swcr_authprepare(axf, *swd, cri->cri_key,
				    cri->cri_klen);
			}

			(*swd)->sw_mlen = cri->cri_mlen;
			(*swd)->sw_axf = axf;
			break;

		case CRYPTO_MD5_KPDK:
			axf = &auth_hash_key_md5;
			goto auth2common;

		case CRYPTO_SHA1_KPDK:
			axf = &auth_hash_key_sha1;
		auth2common:
			(*swd)->sw_ictx = malloc(axf->ctxsize, M_CRYPTO_DATA,
			    M_NOWAIT);
			if ((*swd)->sw_ictx == NULL) {
				swcr_freesession(dev, i);
				return ENOBUFS;
			}

			(*swd)->sw_octx = malloc(cri->cri_klen / 8,
			    M_CRYPTO_DATA, M_NOWAIT);
			if ((*swd)->sw_octx == NULL) {
				swcr_freesession(dev, i);
				return ENOBUFS;
			}

			/* Store the key so we can "append" it to the payload */
			if (cri->cri_key != NULL) {
				swcr_authprepare(axf, *swd, cri->cri_key,
				    cri->cri_klen);
			}

			(*swd)->sw_mlen = cri->cri_mlen;
			(*swd)->sw_axf = axf;
			break;
#ifdef notdef
		case CRYPTO_MD5:
			axf = &auth_hash_md5;
			goto auth3common;

		case CRYPTO_SHA1:
			axf = &auth_hash_sha1;
		auth3common:
			(*swd)->sw_ictx = malloc(axf->ctxsize, M_CRYPTO_DATA,
			    M_NOWAIT);
			if ((*swd)->sw_ictx == NULL) {
				swcr_freesession(dev, i);
				return ENOBUFS;
			}

			axf->Init((*swd)->sw_ictx);
			(*swd)->sw_mlen = cri->cri_mlen;
			(*swd)->sw_axf = axf;
			break;
#endif
		case CRYPTO_DEFLATE_COMP:
			cxf = &comp_algo_deflate;
			(*swd)->sw_cxf = cxf;
			break;
		default:
			swcr_freesession(dev, i);
			return EINVAL;
		}

		(*swd)->sw_alg = cri->cri_alg;
		cri = cri->cri_next;
		swd = &((*swd)->sw_next);
	}
	return 0;
}

/*
 * Free a session.
 */
static int
swcr_freesession(device_t dev, u_int64_t tid)
{
	struct swcr_data *swd;
	struct enc_xform *txf;
	struct auth_hash *axf;
	struct comp_algo *cxf;
	u_int32_t sid = CRYPTO_SESID2LID(tid);

	if (sid > swcr_sesnum || swcr_sessions == NULL ||
	    swcr_sessions[sid] == NULL)
		return EINVAL;

	/* Silently accept and return */
	if (sid == 0)
		return 0;

	while ((swd = swcr_sessions[sid]) != NULL) {
		swcr_sessions[sid] = swd->sw_next;

		switch (swd->sw_alg) {
		case CRYPTO_DES_CBC:
		case CRYPTO_3DES_CBC:
		case CRYPTO_BLF_CBC:
		case CRYPTO_CAST_CBC:
		case CRYPTO_SKIPJACK_CBC:
		case CRYPTO_RIJNDAEL128_CBC:
		case CRYPTO_CAMELLIA_CBC:
		case CRYPTO_NULL_CBC:
			txf = swd->sw_exf;

			if (swd->sw_kschedule)
				txf->zerokey(&(swd->sw_kschedule));
			break;

		case CRYPTO_MD5_HMAC:
		case CRYPTO_SHA1_HMAC:
		case CRYPTO_SHA2_256_HMAC:
		case CRYPTO_SHA2_384_HMAC:
		case CRYPTO_SHA2_512_HMAC:
		case CRYPTO_RIPEMD160_HMAC:
		case CRYPTO_NULL_HMAC:
			axf = swd->sw_axf;

			if (swd->sw_ictx) {
				bzero(swd->sw_ictx, axf->ctxsize);
				free(swd->sw_ictx, M_CRYPTO_DATA);
			}
			if (swd->sw_octx) {
				bzero(swd->sw_octx, axf->ctxsize);
				free(swd->sw_octx, M_CRYPTO_DATA);
			}
			break;

		case CRYPTO_MD5_KPDK:
		case CRYPTO_SHA1_KPDK:
			axf = swd->sw_axf;

			if (swd->sw_ictx) {
				bzero(swd->sw_ictx, axf->ctxsize);
				free(swd->sw_ictx, M_CRYPTO_DATA);
			}
			if (swd->sw_octx) {
				bzero(swd->sw_octx, swd->sw_klen);
				free(swd->sw_octx, M_CRYPTO_DATA);
			}
			break;

		case CRYPTO_MD5:
		case CRYPTO_SHA1:
			axf = swd->sw_axf;

			if (swd->sw_ictx)
				free(swd->sw_ictx, M_CRYPTO_DATA);
			break;

		case CRYPTO_DEFLATE_COMP:
			cxf = swd->sw_cxf;
			break;
		}

		free(swd, M_CRYPTO_DATA);
	}
	return 0;
}

/*
 * Process a software request.
 */
static int
swcr_process(device_t dev, struct cryptop *crp, int hint)
{
	struct cryptodesc *crd;
	struct swcr_data *sw;
	u_int32_t lid;

	/* Sanity check */
	if (crp == NULL)
		return EINVAL;

	if (crp->crp_desc == NULL || crp->crp_buf == NULL) {
		crp->crp_etype = EINVAL;
		goto done;
	}

	lid = crp->crp_sid & 0xffffffff;
	if (lid >= swcr_sesnum || lid == 0 || swcr_sessions[lid] == NULL) {
		crp->crp_etype = ENOENT;
		goto done;
	}

	/* Go through crypto descriptors, processing as we go */
	for (crd = crp->crp_desc; crd; crd = crd->crd_next) {
		/*
		 * Find the crypto context.
		 *
		 * XXX Note that the logic here prevents us from having
		 * XXX the same algorithm multiple times in a session
		 * XXX (or rather, we can but it won't give us the right
		 * XXX results). To do that, we'd need some way of differentiating
		 * XXX between the various instances of an algorithm (so we can
		 * XXX locate the correct crypto context).
		 */
		for (sw = swcr_sessions[lid];
		    sw && sw->sw_alg != crd->crd_alg;
		    sw = sw->sw_next)
			;

		/* No such context ? */
		if (sw == NULL) {
			crp->crp_etype = EINVAL;
			goto done;
		}
		switch (sw->sw_alg) {
		case CRYPTO_DES_CBC:
		case CRYPTO_3DES_CBC:
		case CRYPTO_BLF_CBC:
		case CRYPTO_CAST_CBC:
		case CRYPTO_SKIPJACK_CBC:
		case CRYPTO_RIJNDAEL128_CBC:
		case CRYPTO_CAMELLIA_CBC:
			if ((crp->crp_etype = swcr_encdec(crd, sw,
			    crp->crp_buf, crp->crp_flags)) != 0)
				goto done;
			break;
		case CRYPTO_NULL_CBC:
			crp->crp_etype = 0;
			break;
		case CRYPTO_MD5_HMAC:
		case CRYPTO_SHA1_HMAC:
		case CRYPTO_SHA2_256_HMAC:
		case CRYPTO_SHA2_384_HMAC:
		case CRYPTO_SHA2_512_HMAC:
		case CRYPTO_RIPEMD160_HMAC:
		case CRYPTO_NULL_HMAC:
		case CRYPTO_MD5_KPDK:
		case CRYPTO_SHA1_KPDK:
		case CRYPTO_MD5:
		case CRYPTO_SHA1:
			if ((crp->crp_etype = swcr_authcompute(crd, sw,
			    crp->crp_buf, crp->crp_flags)) != 0)
				goto done;
			break;

		case CRYPTO_DEFLATE_COMP:
			if ((crp->crp_etype = swcr_compdec(crd, sw,
			    crp->crp_buf, crp->crp_flags)) != 0)
				goto done;
			else
				crp->crp_olen = (int)sw->sw_size;
			break;

		default:
			/* Unknown/unsupported algorithm */
			crp->crp_etype = EINVAL;
			goto done;
		}
	}

done:
	crypto_done(crp);
	return 0;
}

static void
swcr_identify(device_t *dev, device_t parent)
{
	/* NB: order 10 is so we get attached after h/w devices */
	if (device_find_child(parent, "cryptosoft", -1) == NULL &&
	    BUS_ADD_CHILD(parent, 10, "cryptosoft", -1) == 0)
		panic("cryptosoft: could not attach");
}

static int
swcr_probe(device_t dev)
{
	device_set_desc(dev, "software crypto");
	return (0);
}

static int
swcr_attach(device_t dev)
{
	memset(hmac_ipad_buffer, HMAC_IPAD_VAL, HMAC_MAX_BLOCK_LEN);
	memset(hmac_opad_buffer, HMAC_OPAD_VAL, HMAC_MAX_BLOCK_LEN);

	swcr_id = crypto_get_driverid(dev,
			CRYPTOCAP_F_SOFTWARE | CRYPTOCAP_F_SYNC);
	if (swcr_id < 0) {
		device_printf(dev, "cannot initialize!");
		return ENOMEM;
	}
#define	REGISTER(alg) \
	crypto_register(swcr_id, alg, 0,0)
	REGISTER(CRYPTO_DES_CBC);
	REGISTER(CRYPTO_3DES_CBC);
	REGISTER(CRYPTO_BLF_CBC);
	REGISTER(CRYPTO_CAST_CBC);
	REGISTER(CRYPTO_SKIPJACK_CBC);
	REGISTER(CRYPTO_NULL_CBC);
	REGISTER(CRYPTO_MD5_HMAC);
	REGISTER(CRYPTO_SHA1_HMAC);
	REGISTER(CRYPTO_SHA2_256_HMAC);
	REGISTER(CRYPTO_SHA2_384_HMAC);
	REGISTER(CRYPTO_SHA2_512_HMAC);
	REGISTER(CRYPTO_RIPEMD160_HMAC);
	REGISTER(CRYPTO_NULL_HMAC);
	REGISTER(CRYPTO_MD5_KPDK);
	REGISTER(CRYPTO_SHA1_KPDK);
	REGISTER(CRYPTO_MD5);
	REGISTER(CRYPTO_SHA1);
	REGISTER(CRYPTO_RIJNDAEL128_CBC);
 	REGISTER(CRYPTO_CAMELLIA_CBC);
	REGISTER(CRYPTO_DEFLATE_COMP);
#undef REGISTER

	return 0;
}

static void
swcr_detach(device_t dev)
{
	crypto_unregister_all(swcr_id);
	if (swcr_sessions != NULL)
		free(swcr_sessions, M_CRYPTO_DATA);
}

static device_method_t swcr_methods[] = {
	DEVMETHOD(device_identify,	swcr_identify),
	DEVMETHOD(device_probe,		swcr_probe),
	DEVMETHOD(device_attach,	swcr_attach),
	DEVMETHOD(device_detach,	swcr_detach),

	DEVMETHOD(cryptodev_newsession,	swcr_newsession),
	DEVMETHOD(cryptodev_freesession,swcr_freesession),
	DEVMETHOD(cryptodev_process,	swcr_process),

	{0, 0},
};

static driver_t swcr_driver = {
	"cryptosoft",
	swcr_methods,
	0,		/* NB: no softc */
};
static devclass_t swcr_devclass;

/*
 * NB: We explicitly reference the crypto module so we
 * get the necessary ordering when built as a loadable
 * module.  This is required because we bundle the crypto
 * module code together with the cryptosoft driver (otherwise
 * normal module dependencies would handle things).
 */
extern int crypto_modevent(struct module *, int, void *);
/* XXX where to attach */
DRIVER_MODULE(cryptosoft, nexus, swcr_driver, swcr_devclass, crypto_modevent,0);
MODULE_VERSION(cryptosoft, 1);
MODULE_DEPEND(cryptosoft, crypto, 1, 1, 1);