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[CRYPTO] lrw: Liskov Rivest Wagner, a tweakable narrow block cipher mode
Main module, this implements the Liskov Rivest Wagner block cipher mode in the new blockcipher API. The implementation is based on ecb.c. The LRW-32-AES specification I used can be found at: http://grouper.ieee.org/groups/1619/email/pdf00017.pdf It implements the optimization specified as optional in the specification, and in addition it uses optimized multiplication routines from gf128mul.c. Since gf128mul.[ch] is not tested on bigendian, this cipher mode may currently fail badly on bigendian machines. Signed-off-by: Rik Snel <rsnel@cube.dyndns.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Rik Snel
David S. Miller
parent
c494e0705d
commit
64470f1b85
@ -168,6 +168,19 @@ config CRYPTO_CBC
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CBC: Cipher Block Chaining mode
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This block cipher algorithm is required for IPSec.
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config CRYPTO_LRW
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tristate "LRW support (EXPERIMENTAL)"
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depends on EXPERIMENTAL
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select CRYPTO_BLKCIPHER
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select CRYPTO_MANAGER
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select CRYPTO_GF128MUL
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help
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LRW: Liskov Rivest Wagner, a tweakable, non malleable, non movable
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narrow block cipher mode for dm-crypt. Use it with cipher
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specification string aes-lrw-benbi, the key must be 256, 320 or 384.
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The first 128, 192 or 256 bits in the key are used for AES and the
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rest is used to tie each cipher block to its logical position.
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config CRYPTO_DES
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tristate "DES and Triple DES EDE cipher algorithms"
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select CRYPTO_ALGAPI
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@ -27,6 +27,7 @@ obj-$(CONFIG_CRYPTO_TGR192) += tgr192.o
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obj-$(CONFIG_CRYPTO_GF128MUL) += gf128mul.o
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obj-$(CONFIG_CRYPTO_ECB) += ecb.o
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obj-$(CONFIG_CRYPTO_CBC) += cbc.o
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obj-$(CONFIG_CRYPTO_LRW) += lrw.o
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obj-$(CONFIG_CRYPTO_DES) += des.o
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obj-$(CONFIG_CRYPTO_BLOWFISH) += blowfish.o
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obj-$(CONFIG_CRYPTO_TWOFISH) += twofish.o
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301
crypto/lrw.c
Normal file
301
crypto/lrw.c
Normal file
@ -0,0 +1,301 @@
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/* LRW: as defined by Cyril Guyot in
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* http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
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*
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* Copyright (c) 2006 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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/* This implementation is checked against the test vectors in the above
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* document and by a test vector provided by Ken Buchanan at
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* http://www.mail-archive.com/stds-p1619@listserv.ieee.org/msg00173.html
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*
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* The test vectors are included in the testing module tcrypt.[ch] */
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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/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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/* optimizes multiplying a random (non incrementing, as at the
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* start of a new sector) value with key2, we could also have
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* used 4k optimization tables or no optimization at all. In the
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* latter case we would have to store key2 here */
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struct gf128mul_64k *table;
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/* stores:
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* key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 },
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* key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 }
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* key2*{ 0,0,...1,1,1,1,1 }, etc
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* needed for optimized multiplication of incrementing values
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* with key2 */
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be128 mulinc[128];
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};
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static inline void setbit128_bbe(void *b, int bit)
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{
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__set_bit(bit ^ 0x78, b);
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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->child;
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int err, i;
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be128 tmp = { 0 };
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int bsize = crypto_cipher_blocksize(child);
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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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if ((err = crypto_cipher_setkey(child, key, keylen - bsize)))
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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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if (ctx->table)
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gf128mul_free_64k(ctx->table);
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/* initialize multiplication table for Key2 */
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ctx->table = gf128mul_init_64k_bbe((be128 *)(key + keylen - bsize));
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if (!ctx->table)
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return -ENOMEM;
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/* initialize optimization table */
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for (i = 0; i < 128; i++) {
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setbit128_bbe(&tmp, i);
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ctx->mulinc[i] = tmp;
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gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
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}
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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 inc(be128 *iv)
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{
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if (!(iv->b = cpu_to_be64(be64_to_cpu(iv->b) + 1)))
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iv->a = cpu_to_be64(be64_to_cpu(iv->a) + 1);
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}
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static inline void 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(Key2,PP) */
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be128_xor(dst, dst, &s->t); /* C <- T xor CC */
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}
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/* this returns the number of consequative 1 bits starting
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* from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
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static inline int get_index128(be128 *block)
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{
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int x;
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__be32 *p = (__be32 *) block;
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for (p += 3, x = 0; x < 128; p--, x += 32) {
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u32 val = be32_to_cpup(p);
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if (!~val)
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continue;
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return x + ffz(val);
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}
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return x;
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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 (*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 = crypto_cipher_blocksize(ctx->child);
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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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be128 *iv;
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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 (!(avail = w->nbytes))
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return err;
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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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iv = (be128 *)w->iv;
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s.t = *iv;
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/* T <- I*Key2 */
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gf128mul_64k_bbe(&s.t, ctx->table);
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goto first;
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for (;;) {
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do {
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/* T <- I*Key2, using the optimization
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* discussed in the specification */
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be128_xor(&s.t, &s.t, &ctx->mulinc[get_index128(iv)]);
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inc(iv);
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first:
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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 (!(avail = w->nbytes))
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break;
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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,
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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,
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crypto_cipher_alg(ctx->child)->cia_decrypt);
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}
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static int init_tfm(struct crypto_tfm *tfm)
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{
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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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tfm = crypto_spawn_tfm(spawn);
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if (IS_ERR(tfm))
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return PTR_ERR(tfm);
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if (crypto_tfm_alg_blocksize(tfm) != 16) {
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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->child = crypto_cipher_cast(tfm);
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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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if (ctx->table)
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gf128mul_free_64k(ctx->table);
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crypto_free_cipher(ctx->child);
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}
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static struct crypto_instance *alloc(void *param, unsigned int len)
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{
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struct crypto_instance *inst;
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struct crypto_alg *alg;
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alg = crypto_get_attr_alg(param, len, CRYPTO_ALG_TYPE_CIPHER,
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CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
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if (IS_ERR(alg))
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return ERR_PTR(PTR_ERR(alg));
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inst = crypto_alloc_instance("lrw", 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) inst->alg.cra_alignmask = 7;
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else inst->alg.cra_alignmask = alg->cra_alignmask;
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inst->alg.cra_type = &crypto_blkcipher_type;
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if (!(alg->cra_blocksize % 4))
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inst->alg.cra_alignmask |= 3;
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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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alg->cra_cipher.cia_min_keysize + alg->cra_blocksize;
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inst->alg.cra_blkcipher.max_keysize =
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alg->cra_cipher.cia_max_keysize + alg->cra_blocksize;
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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 = "lrw",
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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("LRW block cipher mode");
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