[deliverable/linux.git] / net / sunrpc / auth_gss / gss_krb5_crypto.c

/*
 *  linux/net/sunrpc/gss_krb5_crypto.c
 *
 *  Copyright (c) 2000 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Andy Adamson   <andros@umich.edu>
 *  Bruce Fields   <bfields@umich.edu>
 */

/*
 * Copyright (C) 1998 by the FundsXpress, INC.
 *
 * All rights reserved.
 *
 * Export of this software from the United States of America may require
 * a specific license from the United States Government.  It is the
 * responsibility of any person or organization contemplating export to
 * obtain such a license before exporting.
 *
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of FundsXpress. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  FundsXpress makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include <linux/types.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/scatterlist.h>
#include <linux/crypto.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/sunrpc/gss_krb5.h>

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY        RPCDBG_AUTH
#endif

u32
krb5_encrypt(
	struct crypto_tfm *tfm,
	void * iv,
	void * in,
	void * out,
	int length)
{
	u32 ret = -EINVAL;
        struct scatterlist sg[1];
	u8 local_iv[16] = {0};

	dprintk("RPC:      krb5_encrypt: input data:\n");
	print_hexl((u32 *)in, length, 0);

	if (length % crypto_tfm_alg_blocksize(tfm) != 0)
		goto out;

	if (crypto_tfm_alg_ivsize(tfm) > 16) {
		dprintk("RPC:      gss_k5encrypt: tfm iv size to large %d\n",
		         crypto_tfm_alg_ivsize(tfm));
		goto out;
	}

	if (iv)
		memcpy(local_iv, iv, crypto_tfm_alg_ivsize(tfm));

	memcpy(out, in, length);
	sg_set_buf(sg, out, length);

	ret = crypto_cipher_encrypt_iv(tfm, sg, sg, length, local_iv);

	dprintk("RPC:      krb5_encrypt: output data:\n");
	print_hexl((u32 *)out, length, 0);
out:
	dprintk("RPC:      krb5_encrypt returns %d\n",ret);
	return(ret);
}

EXPORT_SYMBOL(krb5_encrypt);

u32
krb5_decrypt(
     struct crypto_tfm *tfm,
     void * iv,
     void * in,
     void * out,
     int length)
{
	u32 ret = -EINVAL;
	struct scatterlist sg[1];
	u8 local_iv[16] = {0};

	dprintk("RPC:      krb5_decrypt: input data:\n");
	print_hexl((u32 *)in, length, 0);

	if (length % crypto_tfm_alg_blocksize(tfm) != 0)
		goto out;

	if (crypto_tfm_alg_ivsize(tfm) > 16) {
		dprintk("RPC:      gss_k5decrypt: tfm iv size to large %d\n",
			crypto_tfm_alg_ivsize(tfm));
		goto out;
	}
	if (iv)
		memcpy(local_iv,iv, crypto_tfm_alg_ivsize(tfm));

	memcpy(out, in, length);
	sg_set_buf(sg, out, length);

	ret = crypto_cipher_decrypt_iv(tfm, sg, sg, length, local_iv);

	dprintk("RPC:      krb5_decrypt: output_data:\n");
	print_hexl((u32 *)out, length, 0);
out:
	dprintk("RPC:      gss_k5decrypt returns %d\n",ret);
	return(ret);
}

EXPORT_SYMBOL(krb5_decrypt);

static int
process_xdr_buf(struct xdr_buf *buf, int offset, int len,
		int (*actor)(struct scatterlist *, void *), void *data)
{
	int i, page_len, thislen, page_offset, ret = 0;
	struct scatterlist	sg[1];

	if (offset >= buf->head[0].iov_len) {
		offset -= buf->head[0].iov_len;
	} else {
		thislen = buf->head[0].iov_len - offset;
		if (thislen > len)
			thislen = len;
		sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
		ret = actor(sg, data);
		if (ret)
			goto out;
		offset = 0;
		len -= thislen;
	}
	if (len == 0)
		goto out;

	if (offset >= buf->page_len) {
		offset -= buf->page_len;
	} else {
		page_len = buf->page_len - offset;
		if (page_len > len)
			page_len = len;
		len -= page_len;
		page_offset = (offset + buf->page_base) & (PAGE_CACHE_SIZE - 1);
		i = (offset + buf->page_base) >> PAGE_CACHE_SHIFT;
		thislen = PAGE_CACHE_SIZE - page_offset;
		do {
			if (thislen > page_len)
				thislen = page_len;
			sg->page = buf->pages[i];
			sg->offset = page_offset;
			sg->length = thislen;
			ret = actor(sg, data);
			if (ret)
				goto out;
			page_len -= thislen;
			i++;
			page_offset = 0;
			thislen = PAGE_CACHE_SIZE;
		} while (page_len != 0);
		offset = 0;
	}
	if (len == 0)
		goto out;

	if (offset < buf->tail[0].iov_len) {
		thislen = buf->tail[0].iov_len - offset;
		if (thislen > len)
			thislen = len;
		sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
		ret = actor(sg, data);
		len -= thislen;
	}
	if (len != 0)
		ret = -EINVAL;
out:
	return ret;
}

static int
checksummer(struct scatterlist *sg, void *data)
{
	struct crypto_tfm *tfm = (struct crypto_tfm *)data;

	crypto_digest_update(tfm, sg, 1);

	return 0;
}

/* checksum the plaintext data and hdrlen bytes of the token header */
s32
make_checksum(s32 cksumtype, char *header, int hdrlen, struct xdr_buf *body,
		   int body_offset, struct xdr_netobj *cksum)
{
	char                            *cksumname;
	struct crypto_tfm               *tfm = NULL; /* XXX add to ctx? */
	struct scatterlist              sg[1];

	switch (cksumtype) {
		case CKSUMTYPE_RSA_MD5:
			cksumname = "md5";
			break;
		default:
			dprintk("RPC:      krb5_make_checksum:"
				" unsupported checksum %d", cksumtype);
			return GSS_S_FAILURE;
	}
	if (!(tfm = crypto_alloc_tfm(cksumname, CRYPTO_TFM_REQ_MAY_SLEEP)))
		return GSS_S_FAILURE;
	cksum->len = crypto_tfm_alg_digestsize(tfm);

	crypto_digest_init(tfm);
	sg_set_buf(sg, header, hdrlen);
	crypto_digest_update(tfm, sg, 1);
	process_xdr_buf(body, body_offset, body->len - body_offset,
			checksummer, tfm);
	crypto_digest_final(tfm, cksum->data);
	crypto_free_tfm(tfm);
	return 0;
}

EXPORT_SYMBOL(make_checksum);

struct encryptor_desc {
	u8 iv[8]; /* XXX hard-coded blocksize */
	struct crypto_tfm *tfm;
	int pos;
	struct xdr_buf *outbuf;
	struct page **pages;
	struct scatterlist infrags[4];
	struct scatterlist outfrags[4];
	int fragno;
	int fraglen;
};

static int
encryptor(struct scatterlist *sg, void *data)
{
	struct encryptor_desc *desc = data;
	struct xdr_buf *outbuf = desc->outbuf;
	struct page *in_page;
	int thislen = desc->fraglen + sg->length;
	int fraglen, ret;
	int page_pos;

	/* Worst case is 4 fragments: head, end of page 1, start
	 * of page 2, tail.  Anything more is a bug. */
	BUG_ON(desc->fragno > 3);
	desc->infrags[desc->fragno] = *sg;
	desc->outfrags[desc->fragno] = *sg;

	page_pos = desc->pos - outbuf->head[0].iov_len;
	if (page_pos >= 0 && page_pos < outbuf->page_len) {
		/* pages are not in place: */
		int i = (page_pos + outbuf->page_base) >> PAGE_CACHE_SHIFT;
		in_page = desc->pages[i];
	} else {
		in_page = sg->page;
	}
	desc->infrags[desc->fragno].page = in_page;
	desc->fragno++;
	desc->fraglen += sg->length;
	desc->pos += sg->length;

	fraglen = thislen & 7; /* XXX hardcoded blocksize */
	thislen -= fraglen;

	if (thislen == 0)
		return 0;

	ret = crypto_cipher_encrypt_iv(desc->tfm, desc->outfrags, desc->infrags,
					thislen, desc->iv);
	if (ret)
		return ret;
	if (fraglen) {
		desc->outfrags[0].page = sg->page;
		desc->outfrags[0].offset = sg->offset + sg->length - fraglen;
		desc->outfrags[0].length = fraglen;
		desc->infrags[0] = desc->outfrags[0];
		desc->infrags[0].page = in_page;
		desc->fragno = 1;
		desc->fraglen = fraglen;
	} else {
		desc->fragno = 0;
		desc->fraglen = 0;
	}
	return 0;
}

int
gss_encrypt_xdr_buf(struct crypto_tfm *tfm, struct xdr_buf *buf, int offset,
		struct page **pages)
{
	int ret;
	struct encryptor_desc desc;

	BUG_ON((buf->len - offset) % crypto_tfm_alg_blocksize(tfm) != 0);

	memset(desc.iv, 0, sizeof(desc.iv));
	desc.tfm = tfm;
	desc.pos = offset;
	desc.outbuf = buf;
	desc.pages = pages;
	desc.fragno = 0;
	desc.fraglen = 0;

	ret = process_xdr_buf(buf, offset, buf->len - offset, encryptor, &desc);
	return ret;
}

EXPORT_SYMBOL(gss_encrypt_xdr_buf);

struct decryptor_desc {
	u8 iv[8]; /* XXX hard-coded blocksize */
	struct crypto_tfm *tfm;
	struct scatterlist frags[4];
	int fragno;
	int fraglen;
};

static int
decryptor(struct scatterlist *sg, void *data)
{
	struct decryptor_desc *desc = data;
	int thislen = desc->fraglen + sg->length;
	int fraglen, ret;

	/* Worst case is 4 fragments: head, end of page 1, start
	 * of page 2, tail.  Anything more is a bug. */
	BUG_ON(desc->fragno > 3);
	desc->frags[desc->fragno] = *sg;
	desc->fragno++;
	desc->fraglen += sg->length;

	fraglen = thislen & 7; /* XXX hardcoded blocksize */
	thislen -= fraglen;

	if (thislen == 0)
		return 0;

	ret = crypto_cipher_decrypt_iv(desc->tfm, desc->frags, desc->frags,
					thislen, desc->iv);
	if (ret)
		return ret;
	if (fraglen) {
		desc->frags[0].page = sg->page;
		desc->frags[0].offset = sg->offset + sg->length - fraglen;
		desc->frags[0].length = fraglen;
		desc->fragno = 1;
		desc->fraglen = fraglen;
	} else {
		desc->fragno = 0;
		desc->fraglen = 0;
	}
	return 0;
}

int
gss_decrypt_xdr_buf(struct crypto_tfm *tfm, struct xdr_buf *buf, int offset)
{
	struct decryptor_desc desc;

	/* XXXJBF: */
	BUG_ON((buf->len - offset) % crypto_tfm_alg_blocksize(tfm) != 0);

	memset(desc.iv, 0, sizeof(desc.iv));
	desc.tfm = tfm;
	desc.fragno = 0;
	desc.fraglen = 0;
	return process_xdr_buf(buf, offset, buf->len - offset, decryptor, &desc);
}

EXPORT_SYMBOL(gss_decrypt_xdr_buf);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/net/sunrpc/gss_krb5_crypto.c
	3	*
	4	* Copyright (c) 2000 The Regents of the University of Michigan.
	5	* All rights reserved.
	6	*
	7	* Andy Adamson <andros@umich.edu>
	8	* Bruce Fields <bfields@umich.edu>
	9	*/
	10
	11	/*
	12	* Copyright (C) 1998 by the FundsXpress, INC.
	13	*
	14	* All rights reserved.
	15	*
	16	* Export of this software from the United States of America may require
	17	* a specific license from the United States Government. It is the
	18	* responsibility of any person or organization contemplating export to
	19	* obtain such a license before exporting.
	20	*
	21	* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
	22	* distribute this software and its documentation for any purpose and
	23	* without fee is hereby granted, provided that the above copyright
	24	* notice appear in all copies and that both that copyright notice and
	25	* this permission notice appear in supporting documentation, and that
	26	* the name of FundsXpress. not be used in advertising or publicity pertaining
	27	* to distribution of the software without specific, written prior
	28	* permission. FundsXpress makes no representations about the suitability of
	29	* this software for any purpose. It is provided "as is" without express
	30	* or implied warranty.
	31	*
	32	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
	33	* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
	34	* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
	35	*/
	36
	37	#include <linux/types.h>
	38	#include <linux/mm.h>
	39	#include <linux/slab.h>
378f058c	40	#include <linux/scatterlist.h>
1da177e4 LT	41	#include <linux/crypto.h>
	42	#include <linux/highmem.h>
	43	#include <linux/pagemap.h>
	44	#include <linux/sunrpc/gss_krb5.h>
	45
	46	#ifdef RPC_DEBUG
	47	# define RPCDBG_FACILITY RPCDBG_AUTH
	48	#endif
	49
	50	u32
	51	krb5_encrypt(
	52	struct crypto_tfm *tfm,
	53	void * iv,
	54	void * in,
	55	void * out,
	56	int length)
	57	{
	58	u32 ret = -EINVAL;
	59	struct scatterlist sg[1];
	60	u8 local_iv[16] = {0};
	61
	62	dprintk("RPC: krb5_encrypt: input data:\n");
	63	print_hexl((u32 *)in, length, 0);
	64
	65	if (length % crypto_tfm_alg_blocksize(tfm) != 0)
	66	goto out;
	67
	68	if (crypto_tfm_alg_ivsize(tfm) > 16) {
	69	dprintk("RPC: gss_k5encrypt: tfm iv size to large %d\n",
	70	crypto_tfm_alg_ivsize(tfm));
	71	goto out;
	72	}
	73
	74	if (iv)
	75	memcpy(local_iv, iv, crypto_tfm_alg_ivsize(tfm));
	76
	77	memcpy(out, in, length);
6df5b9f4	78	sg_set_buf(sg, out, length);
1da177e4 LT	79
	80	ret = crypto_cipher_encrypt_iv(tfm, sg, sg, length, local_iv);
	81
	82	dprintk("RPC: krb5_encrypt: output data:\n");
	83	print_hexl((u32 *)out, length, 0);
	84	out:
	85	dprintk("RPC: krb5_encrypt returns %d\n",ret);
	86	return(ret);
	87	}
	88
	89	EXPORT_SYMBOL(krb5_encrypt);
	90
	91	u32
	92	krb5_decrypt(
	93	struct crypto_tfm *tfm,
	94	void * iv,
	95	void * in,
	96	void * out,
	97	int length)
	98	{
	99	u32 ret = -EINVAL;
	100	struct scatterlist sg[1];
	101	u8 local_iv[16] = {0};
	102
	103	dprintk("RPC: krb5_decrypt: input data:\n");
	104	print_hexl((u32 *)in, length, 0);
	105
	106	if (length % crypto_tfm_alg_blocksize(tfm) != 0)
	107	goto out;
	108
	109	if (crypto_tfm_alg_ivsize(tfm) > 16) {
	110	dprintk("RPC: gss_k5decrypt: tfm iv size to large %d\n",
	111	crypto_tfm_alg_ivsize(tfm));
	112	goto out;
	113	}
	114	if (iv)
	115	memcpy(local_iv,iv, crypto_tfm_alg_ivsize(tfm));
	116
	117	memcpy(out, in, length);
6df5b9f4	118	sg_set_buf(sg, out, length);
1da177e4 LT	119
	120	ret = crypto_cipher_decrypt_iv(tfm, sg, sg, length, local_iv);
	121
	122	dprintk("RPC: krb5_decrypt: output_data:\n");
	123	print_hexl((u32 *)out, length, 0);
	124	out:
	125	dprintk("RPC: gss_k5decrypt returns %d\n",ret);
	126	return(ret);
	127	}
	128
	129	EXPORT_SYMBOL(krb5_decrypt);
	130
f7b3af64 BF	131	static int
	132	process_xdr_buf(struct xdr_buf *buf, int offset, int len,
	133	int (actor)(struct scatterlist , void ), void data)
	134	{
	135	int i, page_len, thislen, page_offset, ret = 0;
	136	struct scatterlist sg[1];
	137
	138	if (offset >= buf->head[0].iov_len) {
	139	offset -= buf->head[0].iov_len;
	140	} else {
	141	thislen = buf->head[0].iov_len - offset;
	142	if (thislen > len)
	143	thislen = len;
378f058c	144	sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
f7b3af64 BF	145	ret = actor(sg, data);
	146	if (ret)
	147	goto out;
	148	offset = 0;
	149	len -= thislen;
	150	}
	151	if (len == 0)
	152	goto out;
	153
	154	if (offset >= buf->page_len) {
	155	offset -= buf->page_len;
	156	} else {
	157	page_len = buf->page_len - offset;
	158	if (page_len > len)
	159	page_len = len;
	160	len -= page_len;
	161	page_offset = (offset + buf->page_base) & (PAGE_CACHE_SIZE - 1);
	162	i = (offset + buf->page_base) >> PAGE_CACHE_SHIFT;
	163	thislen = PAGE_CACHE_SIZE - page_offset;
	164	do {
	165	if (thislen > page_len)
	166	thislen = page_len;
	167	sg->page = buf->pages[i];
	168	sg->offset = page_offset;
	169	sg->length = thislen;
	170	ret = actor(sg, data);
	171	if (ret)
	172	goto out;
	173	page_len -= thislen;
	174	i++;
	175	page_offset = 0;
	176	thislen = PAGE_CACHE_SIZE;
	177	} while (page_len != 0);
	178	offset = 0;
	179	}
	180	if (len == 0)
	181	goto out;
	182
	183	if (offset < buf->tail[0].iov_len) {
	184	thislen = buf->tail[0].iov_len - offset;
	185	if (thislen > len)
	186	thislen = len;
378f058c	187	sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
f7b3af64 BF	188	ret = actor(sg, data);
	189	len -= thislen;
	190	}
	191	if (len != 0)
	192	ret = -EINVAL;
	193	out:
	194	return ret;
	195	}
	196
	197	static int
	198	checksummer(struct scatterlist sg, void data)
	199	{
	200	struct crypto_tfm tfm = (struct crypto_tfm )data;
	201
	202	crypto_digest_update(tfm, sg, 1);
	203
	204	return 0;
	205	}
	206
1da177e4 LT	207	/* checksum the plaintext data and hdrlen bytes of the token header */
	208	s32
	209	make_checksum(s32 cksumtype, char header, int hdrlen, struct xdr_buf body,
14ae162c	210	int body_offset, struct xdr_netobj *cksum)
1da177e4 LT	211	{
	212	char *cksumname;
	213	struct crypto_tfm tfm = NULL; / XXX add to ctx? */
	214	struct scatterlist sg[1];
1da177e4 LT	215
	216	switch (cksumtype) {
	217	case CKSUMTYPE_RSA_MD5:
	218	cksumname = "md5";
	219	break;
	220	default:
	221	dprintk("RPC: krb5_make_checksum:"
	222	" unsupported checksum %d", cksumtype);
d4a30e7e	223	return GSS_S_FAILURE;
1da177e4	224	}
eb6f1160	225	if (!(tfm = crypto_alloc_tfm(cksumname, CRYPTO_TFM_REQ_MAY_SLEEP)))
d4a30e7e	226	return GSS_S_FAILURE;
1da177e4	227	cksum->len = crypto_tfm_alg_digestsize(tfm);
1da177e4 LT	228
1da177e4 LT	229	crypto_digest_init(tfm);
378f058c	230	sg_set_buf(sg, header, hdrlen);
1da177e4	231	crypto_digest_update(tfm, sg, 1);
14ae162c BF	232	process_xdr_buf(body, body_offset, body->len - body_offset,
14ae162c BF	233	checksummer, tfm);
1da177e4	234	crypto_digest_final(tfm, cksum->data);
573dbd95	235	crypto_free_tfm(tfm);
d4a30e7e	236	return 0;
1da177e4 LT	237	}
	238
	239	EXPORT_SYMBOL(make_checksum);
14ae162c BF	240
	241	struct encryptor_desc {
	242	u8 iv[8]; /* XXX hard-coded blocksize */
	243	struct crypto_tfm *tfm;
	244	int pos;
	245	struct xdr_buf *outbuf;
	246	struct page **pages;
	247	struct scatterlist infrags[4];
	248	struct scatterlist outfrags[4];
	249	int fragno;
	250	int fraglen;
	251	};
	252
	253	static int
	254	encryptor(struct scatterlist sg, void data)
	255	{
	256	struct encryptor_desc *desc = data;
	257	struct xdr_buf *outbuf = desc->outbuf;
	258	struct page *in_page;
	259	int thislen = desc->fraglen + sg->length;
	260	int fraglen, ret;
	261	int page_pos;
	262
	263	/* Worst case is 4 fragments: head, end of page 1, start
	264	* of page 2, tail. Anything more is a bug. */
	265	BUG_ON(desc->fragno > 3);
	266	desc->infrags[desc->fragno] = *sg;
	267	desc->outfrags[desc->fragno] = *sg;
	268
	269	page_pos = desc->pos - outbuf->head[0].iov_len;
	270	if (page_pos >= 0 && page_pos < outbuf->page_len) {
	271	/* pages are not in place: */
	272	int i = (page_pos + outbuf->page_base) >> PAGE_CACHE_SHIFT;
	273	in_page = desc->pages[i];
	274	} else {
	275	in_page = sg->page;
	276	}
	277	desc->infrags[desc->fragno].page = in_page;
	278	desc->fragno++;
	279	desc->fraglen += sg->length;
	280	desc->pos += sg->length;
	281
	282	fraglen = thislen & 7; /* XXX hardcoded blocksize */
	283	thislen -= fraglen;
	284
	285	if (thislen == 0)
	286	return 0;
	287
	288	ret = crypto_cipher_encrypt_iv(desc->tfm, desc->outfrags, desc->infrags,
	289	thislen, desc->iv);
	290	if (ret)
	291	return ret;
	292	if (fraglen) {
	293	desc->outfrags[0].page = sg->page;
	294	desc->outfrags[0].offset = sg->offset + sg->length - fraglen;
	295	desc->outfrags[0].length = fraglen;
	296	desc->infrags[0] = desc->outfrags[0];
	297	desc->infrags[0].page = in_page;
	298	desc->fragno = 1;
	299	desc->fraglen = fraglen;
	300	} else {
	301	desc->fragno = 0;
	302	desc->fraglen = 0;
	303	}
304	return 0;
305	}
306
307	int
308	gss_encrypt_xdr_buf(struct crypto_tfm tfm, struct xdr_buf buf, int offset,
309	struct page **pages)
310	{
311	int ret;
312	struct encryptor_desc desc;
313
314	BUG_ON((buf->len - offset) % crypto_tfm_alg_blocksize(tfm) != 0);
315
316	memset(desc.iv, 0, sizeof(desc.iv));
317	desc.tfm = tfm;
318	desc.pos = offset;
319	desc.outbuf = buf;
320	desc.pages = pages;
321	desc.fragno = 0;
322	desc.fraglen = 0;
323
324	ret = process_xdr_buf(buf, offset, buf->len - offset, encryptor, &desc);
325	return ret;
326	}
327
328	EXPORT_SYMBOL(gss_encrypt_xdr_buf);
329
330	struct decryptor_desc {
331	u8 iv[8]; /* XXX hard-coded blocksize */
332	struct crypto_tfm *tfm;
333	struct scatterlist frags[4];
334	int fragno;
335	int fraglen;
336	};
337
338	static int
339	decryptor(struct scatterlist sg, void data)
340	{
341	struct decryptor_desc *desc = data;
342	int thislen = desc->fraglen + sg->length;
343	int fraglen, ret;
344
345	/* Worst case is 4 fragments: head, end of page 1, start
346	* of page 2, tail. Anything more is a bug. */
347	BUG_ON(desc->fragno > 3);
348	desc->frags[desc->fragno] = *sg;
349	desc->fragno++;
350	desc->fraglen += sg->length;
351
352	fraglen = thislen & 7; /* XXX hardcoded blocksize */
353	thislen -= fraglen;
354
355	if (thislen == 0)
356	return 0;
357
358	ret = crypto_cipher_decrypt_iv(desc->tfm, desc->frags, desc->frags,
359	thislen, desc->iv);
360	if (ret)
361	return ret;
362	if (fraglen) {
363	desc->frags[0].page = sg->page;
364	desc->frags[0].offset = sg->offset + sg->length - fraglen;
365	desc->frags[0].length = fraglen;
366	desc->fragno = 1;
367	desc->fraglen = fraglen;
368	} else {
369	desc->fragno = 0;
370	desc->fraglen = 0;
371	}
372	return 0;
373	}
374
375	int
376	gss_decrypt_xdr_buf(struct crypto_tfm tfm, struct xdr_buf buf, int offset)
377	{
378	struct decryptor_desc desc;
379
380	/* XXXJBF: */
381	BUG_ON((buf->len - offset) % crypto_tfm_alg_blocksize(tfm) != 0);
382
383	memset(desc.iv, 0, sizeof(desc.iv));
384	desc.tfm = tfm;
385	desc.fragno = 0;
386	desc.fraglen = 0;
387	return process_xdr_buf(buf, offset, buf->len - offset, decryptor, &desc);
388	}
389
390	EXPORT_SYMBOL(gss_decrypt_xdr_buf);