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![Jussi Kivilinna](/assets/img/avatar_default.png)
Add xts_crypt() function that can be used by cipher implementations that can benefit from parallelized cipher operations. Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
364 lines
8.7 KiB
C
364 lines
8.7 KiB
C
/* XTS: as defined in IEEE1619/D16
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* http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
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* (sector sizes which are not a multiple of 16 bytes are,
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* however currently unsupported)
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*
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* Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org>
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*
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* Based om ecb.c
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* Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*/
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#include <crypto/algapi.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/scatterlist.h>
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#include <linux/slab.h>
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#include <crypto/xts.h>
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#include <crypto/b128ops.h>
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#include <crypto/gf128mul.h>
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struct priv {
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struct crypto_cipher *child;
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struct crypto_cipher *tweak;
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};
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static int setkey(struct crypto_tfm *parent, const u8 *key,
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unsigned int keylen)
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{
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struct priv *ctx = crypto_tfm_ctx(parent);
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struct crypto_cipher *child = ctx->tweak;
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u32 *flags = &parent->crt_flags;
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int err;
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/* key consists of keys of equal size concatenated, therefore
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* the length must be even */
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if (keylen % 2) {
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/* tell the user why there was an error */
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*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
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return -EINVAL;
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}
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/* we need two cipher instances: one to compute the initial 'tweak'
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* by encrypting the IV (usually the 'plain' iv) and the other
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* one to encrypt and decrypt the data */
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/* tweak cipher, uses Key2 i.e. the second half of *key */
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crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
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crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
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CRYPTO_TFM_REQ_MASK);
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err = crypto_cipher_setkey(child, key + keylen/2, keylen/2);
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if (err)
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return err;
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crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
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CRYPTO_TFM_RES_MASK);
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child = ctx->child;
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/* data cipher, uses Key1 i.e. the first half of *key */
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crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
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crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
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CRYPTO_TFM_REQ_MASK);
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err = crypto_cipher_setkey(child, key, keylen/2);
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if (err)
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return err;
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crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
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CRYPTO_TFM_RES_MASK);
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return 0;
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}
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struct sinfo {
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be128 *t;
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struct crypto_tfm *tfm;
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
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};
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static inline void xts_round(struct sinfo *s, void *dst, const void *src)
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{
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be128_xor(dst, s->t, src); /* PP <- T xor P */
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s->fn(s->tfm, dst, dst); /* CC <- E(Key1,PP) */
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be128_xor(dst, dst, s->t); /* C <- T xor CC */
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}
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static int crypt(struct blkcipher_desc *d,
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struct blkcipher_walk *w, struct priv *ctx,
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void (*tw)(struct crypto_tfm *, u8 *, const u8 *),
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
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{
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int err;
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unsigned int avail;
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const int bs = XTS_BLOCK_SIZE;
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struct sinfo s = {
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.tfm = crypto_cipher_tfm(ctx->child),
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.fn = fn
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};
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u8 *wsrc;
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u8 *wdst;
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err = blkcipher_walk_virt(d, w);
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if (!w->nbytes)
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return err;
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s.t = (be128 *)w->iv;
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avail = w->nbytes;
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wsrc = w->src.virt.addr;
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wdst = w->dst.virt.addr;
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/* calculate first value of T */
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tw(crypto_cipher_tfm(ctx->tweak), w->iv, w->iv);
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goto first;
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for (;;) {
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do {
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gf128mul_x_ble(s.t, s.t);
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first:
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xts_round(&s, wdst, wsrc);
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wsrc += bs;
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wdst += bs;
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} while ((avail -= bs) >= bs);
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err = blkcipher_walk_done(d, w, avail);
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if (!w->nbytes)
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break;
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avail = w->nbytes;
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wsrc = w->src.virt.addr;
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wdst = w->dst.virt.addr;
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}
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return err;
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}
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static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
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struct scatterlist *src, unsigned int nbytes)
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{
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struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
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struct blkcipher_walk w;
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blkcipher_walk_init(&w, dst, src, nbytes);
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return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
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crypto_cipher_alg(ctx->child)->cia_encrypt);
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}
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static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
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struct scatterlist *src, unsigned int nbytes)
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{
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struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
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struct blkcipher_walk w;
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blkcipher_walk_init(&w, dst, src, nbytes);
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return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
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crypto_cipher_alg(ctx->child)->cia_decrypt);
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}
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int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
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struct scatterlist *ssrc, unsigned int nbytes,
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struct xts_crypt_req *req)
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{
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const unsigned int bsize = XTS_BLOCK_SIZE;
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const unsigned int max_blks = req->tbuflen / bsize;
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struct blkcipher_walk walk;
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unsigned int nblocks;
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be128 *src, *dst, *t;
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be128 *t_buf = req->tbuf;
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int err, i;
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BUG_ON(max_blks < 1);
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blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
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err = blkcipher_walk_virt(desc, &walk);
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nbytes = walk.nbytes;
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if (!nbytes)
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return err;
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nblocks = min(nbytes / bsize, max_blks);
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src = (be128 *)walk.src.virt.addr;
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dst = (be128 *)walk.dst.virt.addr;
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/* calculate first value of T */
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req->tweak_fn(req->tweak_ctx, (u8 *)&t_buf[0], walk.iv);
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i = 0;
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goto first;
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for (;;) {
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do {
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for (i = 0; i < nblocks; i++) {
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gf128mul_x_ble(&t_buf[i], t);
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first:
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t = &t_buf[i];
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/* PP <- T xor P */
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be128_xor(dst + i, t, src + i);
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}
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/* CC <- E(Key2,PP) */
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req->crypt_fn(req->crypt_ctx, (u8 *)dst,
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nblocks * bsize);
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/* C <- T xor CC */
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for (i = 0; i < nblocks; i++)
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be128_xor(dst + i, dst + i, &t_buf[i]);
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src += nblocks;
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dst += nblocks;
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nbytes -= nblocks * bsize;
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nblocks = min(nbytes / bsize, max_blks);
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} while (nblocks > 0);
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*(be128 *)walk.iv = *t;
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err = blkcipher_walk_done(desc, &walk, nbytes);
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nbytes = walk.nbytes;
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if (!nbytes)
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break;
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nblocks = min(nbytes / bsize, max_blks);
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src = (be128 *)walk.src.virt.addr;
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dst = (be128 *)walk.dst.virt.addr;
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}
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return err;
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}
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EXPORT_SYMBOL_GPL(xts_crypt);
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static int init_tfm(struct crypto_tfm *tfm)
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{
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struct crypto_cipher *cipher;
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struct crypto_instance *inst = (void *)tfm->__crt_alg;
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struct crypto_spawn *spawn = crypto_instance_ctx(inst);
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struct priv *ctx = crypto_tfm_ctx(tfm);
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u32 *flags = &tfm->crt_flags;
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cipher = crypto_spawn_cipher(spawn);
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if (IS_ERR(cipher))
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return PTR_ERR(cipher);
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if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
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*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
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crypto_free_cipher(cipher);
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return -EINVAL;
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}
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ctx->child = cipher;
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cipher = crypto_spawn_cipher(spawn);
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if (IS_ERR(cipher)) {
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crypto_free_cipher(ctx->child);
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return PTR_ERR(cipher);
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}
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/* this check isn't really needed, leave it here just in case */
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if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
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crypto_free_cipher(cipher);
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crypto_free_cipher(ctx->child);
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*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
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return -EINVAL;
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}
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ctx->tweak = cipher;
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return 0;
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}
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static void exit_tfm(struct crypto_tfm *tfm)
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{
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struct priv *ctx = crypto_tfm_ctx(tfm);
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crypto_free_cipher(ctx->child);
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crypto_free_cipher(ctx->tweak);
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}
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static struct crypto_instance *alloc(struct rtattr **tb)
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{
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struct crypto_instance *inst;
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struct crypto_alg *alg;
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int err;
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err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
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if (err)
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return ERR_PTR(err);
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alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
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CRYPTO_ALG_TYPE_MASK);
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if (IS_ERR(alg))
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return ERR_CAST(alg);
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inst = crypto_alloc_instance("xts", alg);
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if (IS_ERR(inst))
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goto out_put_alg;
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inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
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inst->alg.cra_priority = alg->cra_priority;
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inst->alg.cra_blocksize = alg->cra_blocksize;
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if (alg->cra_alignmask < 7)
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inst->alg.cra_alignmask = 7;
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else
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inst->alg.cra_alignmask = alg->cra_alignmask;
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inst->alg.cra_type = &crypto_blkcipher_type;
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inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
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inst->alg.cra_blkcipher.min_keysize =
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2 * alg->cra_cipher.cia_min_keysize;
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inst->alg.cra_blkcipher.max_keysize =
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2 * alg->cra_cipher.cia_max_keysize;
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inst->alg.cra_ctxsize = sizeof(struct priv);
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inst->alg.cra_init = init_tfm;
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inst->alg.cra_exit = exit_tfm;
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inst->alg.cra_blkcipher.setkey = setkey;
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inst->alg.cra_blkcipher.encrypt = encrypt;
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inst->alg.cra_blkcipher.decrypt = decrypt;
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out_put_alg:
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crypto_mod_put(alg);
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return inst;
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}
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static void free(struct crypto_instance *inst)
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{
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crypto_drop_spawn(crypto_instance_ctx(inst));
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kfree(inst);
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}
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static struct crypto_template crypto_tmpl = {
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.name = "xts",
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.alloc = alloc,
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.free = free,
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.module = THIS_MODULE,
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};
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static int __init crypto_module_init(void)
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{
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return crypto_register_template(&crypto_tmpl);
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}
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static void __exit crypto_module_exit(void)
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{
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crypto_unregister_template(&crypto_tmpl);
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}
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module_init(crypto_module_init);
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module_exit(crypto_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("XTS block cipher mode");
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