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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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+
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+#include <crypto/b128ops.h>
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+#include <crypto/gf128mul.h>
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+
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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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+
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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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+
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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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+
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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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+
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+ if (ctx->table)
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+ gf128mul_free_64k(ctx->table);
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+
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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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+
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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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+
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+ return 0;
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+}
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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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+
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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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+
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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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+
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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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+
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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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+
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+ if (!~val)
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+ continue;
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+
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+ return x + ffz(val);
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+ }
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+
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+ return x;
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+}
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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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+
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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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+
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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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+ /* calculate first value of T */
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+ iv = (be128 *)w->iv;
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+ s.t = *iv;
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+
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+ /* T <- I*Key2 */
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+ gf128mul_64k_bbe(&s.t, ctx->table);
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+
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+ goto first;
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+
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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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+
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+first:
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+ round(&s, wdst, wsrc);
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+
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+ wsrc += bs;
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+ wdst += bs;
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+ } while ((avail -= bs) >= bs);
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+
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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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+
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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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+
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+ return err;
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+}
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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+ ctx->child = crypto_cipher_cast(tfm);
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+ return 0;
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+}
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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+ inst->alg.cra_ctxsize = sizeof(struct priv);
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+
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+ inst->alg.cra_init = init_tfm;
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+ inst->alg.cra_exit = exit_tfm;
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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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+module_init(crypto_module_init);
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+module_exit(crypto_module_exit);
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+
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+MODULE_LICENSE("GPL");
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+MODULE_DESCRIPTION("LRW block cipher mode");
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