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