1 files changed, 544 insertions, 0 deletions
diff --git a/crypto/xts.c b/crypto/xts.c
new file mode 100644
index 000000000..5542dd10a
--- /dev/null
+++ b/crypto/xts.c
@@ -0,0 +1,544 @@
+/* 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 on 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/internal/skcipher.h>
+#include <crypto/scatterwalk.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>
+
+#define XTS_BUFFER_SIZE 128u
+
+struct priv {
+	struct crypto_skcipher *child;
+	struct crypto_cipher *tweak;
+};
+
+struct xts_instance_ctx {
+	struct crypto_skcipher_spawn spawn;
+	char name[CRYPTO_MAX_ALG_NAME];
+};
+
+struct rctx {
+	le128 buf[XTS_BUFFER_SIZE / sizeof(le128)];
+
+	le128 t;
+
+	le128 *ext;
+
+	struct scatterlist srcbuf[2];
+	struct scatterlist dstbuf[2];
+	struct scatterlist *src;
+	struct scatterlist *dst;
+
+	unsigned int left;
+
+	struct skcipher_request subreq;
+};
+
+static int setkey(struct crypto_skcipher *parent, const u8 *key,
+		  unsigned int keylen)
+{
+	struct priv *ctx = crypto_skcipher_ctx(parent);
+	struct crypto_skcipher *child;
+	struct crypto_cipher *tweak;
+	int err;
+
+	err = xts_verify_key(parent, key, keylen);
+	if (err)
+		return err;
+
+	keylen /= 2;
+
+	/* 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 */
+	tweak = ctx->tweak;
+	crypto_cipher_clear_flags(tweak, CRYPTO_TFM_REQ_MASK);
+	crypto_cipher_set_flags(tweak, crypto_skcipher_get_flags(parent) &
+				       CRYPTO_TFM_REQ_MASK);
+	err = crypto_cipher_setkey(tweak, key + keylen, keylen);
+	crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(tweak) &
+					  CRYPTO_TFM_RES_MASK);
+	if (err)
+		return err;
+
+	/* data cipher, uses Key1 i.e. the first half of *key */
+	child = ctx->child;
+	crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
+	crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
+					 CRYPTO_TFM_REQ_MASK);
+	err = crypto_skcipher_setkey(child, key, keylen);
+	crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
+					  CRYPTO_TFM_RES_MASK);
+
+	return err;
+}
+
+static int post_crypt(struct skcipher_request *req)
+{
+	struct rctx *rctx = skcipher_request_ctx(req);
+	le128 *buf = rctx->ext ?: rctx->buf;
+	struct skcipher_request *subreq;
+	const int bs = XTS_BLOCK_SIZE;
+	struct skcipher_walk w;
+	struct scatterlist *sg;
+	unsigned offset;
+	int err;
+
+	subreq = &rctx->subreq;
+	err = skcipher_walk_virt(&w, subreq, false);
+
+	while (w.nbytes) {
+		unsigned int avail = w.nbytes;
+		le128 *wdst;
+
+		wdst = w.dst.virt.addr;
+
+		do {
+			le128_xor(wdst, buf++, wdst);
+			wdst++;
+		} while ((avail -= bs) >= bs);
+
+		err = skcipher_walk_done(&w, avail);
+	}
+
+	rctx->left -= subreq->cryptlen;
+
+	if (err || !rctx->left)
+		goto out;
+
+	rctx->dst = rctx->dstbuf;
+
+	scatterwalk_done(&w.out, 0, 1);
+	sg = w.out.sg;
+	offset = w.out.offset;
+
+	if (rctx->dst != sg) {
+		rctx->dst[0] = *sg;
+		sg_unmark_end(rctx->dst);
+		scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 2);
+	}
+	rctx->dst[0].length -= offset - sg->offset;
+	rctx->dst[0].offset = offset;
+
+out:
+	return err;
+}
+
+static int pre_crypt(struct skcipher_request *req)
+{
+	struct rctx *rctx = skcipher_request_ctx(req);
+	le128 *buf = rctx->ext ?: rctx->buf;
+	struct skcipher_request *subreq;
+	const int bs = XTS_BLOCK_SIZE;
+	struct skcipher_walk w;
+	struct scatterlist *sg;
+	unsigned cryptlen;
+	unsigned offset;
+	bool more;
+	int err;
+
+	subreq = &rctx->subreq;
+	cryptlen = subreq->cryptlen;
+
+	more = rctx->left > cryptlen;
+	if (!more)
+		cryptlen = rctx->left;
+
+	skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
+				   cryptlen, NULL);
+
+	err = skcipher_walk_virt(&w, subreq, false);
+
+	while (w.nbytes) {
+		unsigned int avail = w.nbytes;
+		le128 *wsrc;
+		le128 *wdst;
+
+		wsrc = w.src.virt.addr;
+		wdst = w.dst.virt.addr;
+
+		do {
+			*buf++ = rctx->t;
+			le128_xor(wdst++, &rctx->t, wsrc++);
+			gf128mul_x_ble(&rctx->t, &rctx->t);
+		} while ((avail -= bs) >= bs);
+
+		err = skcipher_walk_done(&w, avail);
+	}
+
+	skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
+				   cryptlen, NULL);
+
+	if (err || !more)
+		goto out;
+
+	rctx->src = rctx->srcbuf;
+
+	scatterwalk_done(&w.in, 0, 1);
+	sg = w.in.sg;
+	offset = w.in.offset;
+
+	if (rctx->src != sg) {
+		rctx->src[0] = *sg;
+		sg_unmark_end(rctx->src);
+		scatterwalk_crypto_chain(rctx->src, sg_next(sg), 2);
+	}
+	rctx->src[0].length -= offset - sg->offset;
+	rctx->src[0].offset = offset;
+
+out:
+	return err;
+}
+
+static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
+{
+	struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
+	struct rctx *rctx = skcipher_request_ctx(req);
+	struct skcipher_request *subreq;
+	gfp_t gfp;
+
+	subreq = &rctx->subreq;
+	skcipher_request_set_tfm(subreq, ctx->child);
+	skcipher_request_set_callback(subreq, req->base.flags, done, req);
+
+	gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
+							   GFP_ATOMIC;
+	rctx->ext = NULL;
+
+	subreq->cryptlen = XTS_BUFFER_SIZE;
+	if (req->cryptlen > XTS_BUFFER_SIZE) {
+		unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
+
+		rctx->ext = kmalloc(n, gfp);
+		if (rctx->ext)
+			subreq->cryptlen = n;
+	}
+
+	rctx->src = req->src;
+	rctx->dst = req->dst;
+	rctx->left = req->cryptlen;
+
+	/* calculate first value of T */
+	crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv);
+
+	return 0;
+}
+
+static void exit_crypt(struct skcipher_request *req)
+{
+	struct rctx *rctx = skcipher_request_ctx(req);
+
+	rctx->left = 0;
+
+	if (rctx->ext)
+		kzfree(rctx->ext);
+}
+
+static int do_encrypt(struct skcipher_request *req, int err)
+{
+	struct rctx *rctx = skcipher_request_ctx(req);
+	struct skcipher_request *subreq;
+
+	subreq = &rctx->subreq;
+
+	while (!err && rctx->left) {
+		err = pre_crypt(req) ?:
+		      crypto_skcipher_encrypt(subreq) ?:
+		      post_crypt(req);
+
+		if (err == -EINPROGRESS || err == -EBUSY)
+			return err;
+	}
+
+	exit_crypt(req);
+	return err;
+}
+
+static void encrypt_done(struct crypto_async_request *areq, int err)
+{
+	struct skcipher_request *req = areq->data;
+	struct skcipher_request *subreq;
+	struct rctx *rctx;
+
+	rctx = skcipher_request_ctx(req);
+
+	if (err == -EINPROGRESS) {
+		if (rctx->left != req->cryptlen)
+			return;
+		goto out;
+	}
+
+	subreq = &rctx->subreq;
+	subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
+
+	err = do_encrypt(req, err ?: post_crypt(req));
+	if (rctx->left)
+		return;
+
+out:
+	skcipher_request_complete(req, err);
+}
+
+static int encrypt(struct skcipher_request *req)
+{
+	return do_encrypt(req, init_crypt(req, encrypt_done));
+}
+
+static int do_decrypt(struct skcipher_request *req, int err)
+{
+	struct rctx *rctx = skcipher_request_ctx(req);
+	struct skcipher_request *subreq;
+
+	subreq = &rctx->subreq;
+
+	while (!err && rctx->left) {
+		err = pre_crypt(req) ?:
+		      crypto_skcipher_decrypt(subreq) ?:
+		      post_crypt(req);
+
+		if (err == -EINPROGRESS || err == -EBUSY)
+			return err;
+	}
+
+	exit_crypt(req);
+	return err;
+}
+
+static void decrypt_done(struct crypto_async_request *areq, int err)
+{
+	struct skcipher_request *req = areq->data;
+	struct skcipher_request *subreq;
+	struct rctx *rctx;
+
+	rctx = skcipher_request_ctx(req);
+
+	if (err == -EINPROGRESS) {
+		if (rctx->left != req->cryptlen)
+			return;
+		goto out;
+	}
+
+	subreq = &rctx->subreq;
+	subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
+
+	err = do_decrypt(req, err ?: post_crypt(req));
+	if (rctx->left)
+		return;
+
+out:
+	skcipher_request_complete(req, err);
+}
+
+static int decrypt(struct skcipher_request *req)
+{
+	return do_decrypt(req, init_crypt(req, decrypt_done));
+}
+
+static int init_tfm(struct crypto_skcipher *tfm)
+{
+	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
+	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
+	struct priv *ctx = crypto_skcipher_ctx(tfm);
+	struct crypto_skcipher *child;
+	struct crypto_cipher *tweak;
+
+	child = crypto_spawn_skcipher(&ictx->spawn);
+	if (IS_ERR(child))
+		return PTR_ERR(child);
+
+	ctx->child = child;
+
+	tweak = crypto_alloc_cipher(ictx->name, 0, 0);
+	if (IS_ERR(tweak)) {
+		crypto_free_skcipher(ctx->child);
+		return PTR_ERR(tweak);
+	}
+
+	ctx->tweak = tweak;
+
+	crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) +
+					 sizeof(struct rctx));
+
+	return 0;
+}
+
+static void exit_tfm(struct crypto_skcipher *tfm)
+{
+	struct priv *ctx = crypto_skcipher_ctx(tfm);
+
+	crypto_free_skcipher(ctx->child);
+	crypto_free_cipher(ctx->tweak);
+}
+
+static void free_inst(struct skcipher_instance *inst)
+{
+	crypto_drop_skcipher(skcipher_instance_ctx(inst));
+	kfree(inst);
+}
+
+static int create(struct crypto_template *tmpl, struct rtattr **tb)
+{
+	struct skcipher_instance *inst;
+	struct crypto_attr_type *algt;
+	struct xts_instance_ctx *ctx;
+	struct skcipher_alg *alg;
+	const char *cipher_name;
+	u32 mask;
+	int err;
+
+	algt = crypto_get_attr_type(tb);
+	if (IS_ERR(algt))
+		return PTR_ERR(algt);
+
+	if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
+		return -EINVAL;
+
+	cipher_name = crypto_attr_alg_name(tb[1]);
+	if (IS_ERR(cipher_name))
+		return PTR_ERR(cipher_name);
+
+	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
+	if (!inst)
+		return -ENOMEM;
+
+	ctx = skcipher_instance_ctx(inst);
+
+	crypto_set_skcipher_spawn(&ctx->spawn, skcipher_crypto_instance(inst));
+
+	mask = crypto_requires_off(algt->type, algt->mask,
+				   CRYPTO_ALG_NEED_FALLBACK |
+				   CRYPTO_ALG_ASYNC);
+
+	err = crypto_grab_skcipher(&ctx->spawn, cipher_name, 0, mask);
+	if (err == -ENOENT) {
+		err = -ENAMETOOLONG;
+		if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
+			     cipher_name) >= CRYPTO_MAX_ALG_NAME)
+			goto err_free_inst;
+
+		err = crypto_grab_skcipher(&ctx->spawn, ctx->name, 0, mask);
+	}
+
+	if (err)
+		goto err_free_inst;
+
+	alg = crypto_skcipher_spawn_alg(&ctx->spawn);
+
+	err = -EINVAL;
+	if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
+		goto err_drop_spawn;
+
+	if (crypto_skcipher_alg_ivsize(alg))
+		goto err_drop_spawn;
+
+	err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
+				  &alg->base);
+	if (err)
+		goto err_drop_spawn;
+
+	err = -EINVAL;
+	cipher_name = alg->base.cra_name;
+
+	/* Alas we screwed up the naming so we have to mangle the
+	 * cipher name.
+	 */
+	if (!strncmp(cipher_name, "ecb(", 4)) {
+		unsigned len;
+
+		len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
+		if (len < 2 || len >= sizeof(ctx->name))
+			goto err_drop_spawn;
+
+		if (ctx->name[len - 1] != ')')
+			goto err_drop_spawn;
+
+		ctx->name[len - 1] = 0;
+
+		if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
+			     "xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME) {
+			err = -ENAMETOOLONG;
+			goto err_drop_spawn;
+		}
+	} else
+		goto err_drop_spawn;
+
+	inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
+	inst->alg.base.cra_priority = alg->base.cra_priority;
+	inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
+	inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
+				       (__alignof__(u64) - 1);
+
+	inst->alg.ivsize = XTS_BLOCK_SIZE;
+	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2;
+	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2;
+
+	inst->alg.base.cra_ctxsize = sizeof(struct priv);
+
+	inst->alg.init = init_tfm;
+	inst->alg.exit = exit_tfm;
+
+	inst->alg.setkey = setkey;
+	inst->alg.encrypt = encrypt;
+	inst->alg.decrypt = decrypt;
+
+	inst->free = free_inst;
+
+	err = skcipher_register_instance(tmpl, inst);
+	if (err)
+		goto err_drop_spawn;
+
+out:
+	return err;
+
+err_drop_spawn:
+	crypto_drop_skcipher(&ctx->spawn);
+err_free_inst:
+	kfree(inst);
+	goto out;
+}
+
+static struct crypto_template crypto_tmpl = {
+	.name = "xts",
+	.create = create,
+	.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");