1 files changed, 466 insertions, 0 deletions

diff --git a/crypto/xts.c b/crypto/xts.c
new file mode 100644
index 000000000..74dc199d5
--- /dev/null
+++ b/crypto/xts.c
@@ -0,0 +1,466 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* XTS: as defined in IEEE1619/D16
+ *	http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
+ *
+ * Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org>
+ *
+ * Based on ecb.c
+ * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+#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>
+
+struct xts_tfm_ctx {
+	struct crypto_skcipher *child;
+	struct crypto_cipher *tweak;
+};
+
+struct xts_instance_ctx {
+	struct crypto_skcipher_spawn spawn;
+	char name[CRYPTO_MAX_ALG_NAME];
+};
+
+struct xts_request_ctx {
+	le128 t;
+	struct scatterlist *tail;
+	struct scatterlist sg[2];
+	struct skcipher_request subreq;
+};
+
+static int xts_setkey(struct crypto_skcipher *parent, const u8 *key,
+		      unsigned int keylen)
+{
+	struct xts_tfm_ctx *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);
+	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);
+	return crypto_skcipher_setkey(child, key, keylen);
+}
+
+/*
+ * We compute the tweak masks twice (both before and after the ECB encryption or
+ * decryption) to avoid having to allocate a temporary buffer and/or make
+ * mutliple calls to the 'ecb(..)' instance, which usually would be slower than
+ * just doing the gf128mul_x_ble() calls again.
+ */
+static int xts_xor_tweak(struct skcipher_request *req, bool second_pass,
+			 bool enc)
+{
+	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	const bool cts = (req->cryptlen % XTS_BLOCK_SIZE);
+	const int bs = XTS_BLOCK_SIZE;
+	struct skcipher_walk w;
+	le128 t = rctx->t;
+	int err;
+
+	if (second_pass) {
+		req = &rctx->subreq;
+		/* set to our TFM to enforce correct alignment: */
+		skcipher_request_set_tfm(req, tfm);
+	}
+	err = skcipher_walk_virt(&w, req, false);
+
+	while (w.nbytes) {
+		unsigned int avail = w.nbytes;
+		le128 *wsrc;
+		le128 *wdst;
+
+		wsrc = w.src.virt.addr;
+		wdst = w.dst.virt.addr;
+
+		do {
+			if (unlikely(cts) &&
+			    w.total - w.nbytes + avail < 2 * XTS_BLOCK_SIZE) {
+				if (!enc) {
+					if (second_pass)
+						rctx->t = t;
+					gf128mul_x_ble(&t, &t);
+				}
+				le128_xor(wdst, &t, wsrc);
+				if (enc && second_pass)
+					gf128mul_x_ble(&rctx->t, &t);
+				skcipher_walk_done(&w, avail - bs);
+				return 0;
+			}
+
+			le128_xor(wdst++, &t, wsrc++);
+			gf128mul_x_ble(&t, &t);
+		} while ((avail -= bs) >= bs);
+
+		err = skcipher_walk_done(&w, avail);
+	}
+
+	return err;
+}
+
+static int xts_xor_tweak_pre(struct skcipher_request *req, bool enc)
+{
+	return xts_xor_tweak(req, false, enc);
+}
+
+static int xts_xor_tweak_post(struct skcipher_request *req, bool enc)
+{
+	return xts_xor_tweak(req, true, enc);
+}
+
+static void xts_cts_done(struct crypto_async_request *areq, int err)
+{
+	struct skcipher_request *req = areq->data;
+	le128 b;
+
+	if (!err) {
+		struct xts_request_ctx *rctx = skcipher_request_ctx(req);
+
+		scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
+		le128_xor(&b, &rctx->t, &b);
+		scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);
+	}
+
+	skcipher_request_complete(req, err);
+}
+
+static int xts_cts_final(struct skcipher_request *req,
+			 int (*crypt)(struct skcipher_request *req))
+{
+	const struct xts_tfm_ctx *ctx =
+		crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
+	int offset = req->cryptlen & ~(XTS_BLOCK_SIZE - 1);
+	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
+	struct skcipher_request *subreq = &rctx->subreq;
+	int tail = req->cryptlen % XTS_BLOCK_SIZE;
+	le128 b[2];
+	int err;
+
+	rctx->tail = scatterwalk_ffwd(rctx->sg, req->dst,
+				      offset - XTS_BLOCK_SIZE);
+
+	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
+	b[1] = b[0];
+	scatterwalk_map_and_copy(b, req->src, offset, tail, 0);
+
+	le128_xor(b, &rctx->t, b);
+
+	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE + tail, 1);
+
+	skcipher_request_set_tfm(subreq, ctx->child);
+	skcipher_request_set_callback(subreq, req->base.flags, xts_cts_done,
+				      req);
+	skcipher_request_set_crypt(subreq, rctx->tail, rctx->tail,
+				   XTS_BLOCK_SIZE, NULL);
+
+	err = crypt(subreq);
+	if (err)
+		return err;
+
+	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
+	le128_xor(b, &rctx->t, b);
+	scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);
+
+	return 0;
+}
+
+static void xts_encrypt_done(struct crypto_async_request *areq, int err)
+{
+	struct skcipher_request *req = areq->data;
+
+	if (!err) {
+		struct xts_request_ctx *rctx = skcipher_request_ctx(req);
+
+		rctx->subreq.base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
+		err = xts_xor_tweak_post(req, true);
+
+		if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
+			err = xts_cts_final(req, crypto_skcipher_encrypt);
+			if (err == -EINPROGRESS || err == -EBUSY)
+				return;
+		}
+	}
+
+	skcipher_request_complete(req, err);
+}
+
+static void xts_decrypt_done(struct crypto_async_request *areq, int err)
+{
+	struct skcipher_request *req = areq->data;
+
+	if (!err) {
+		struct xts_request_ctx *rctx = skcipher_request_ctx(req);
+
+		rctx->subreq.base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
+		err = xts_xor_tweak_post(req, false);
+
+		if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
+			err = xts_cts_final(req, crypto_skcipher_decrypt);
+			if (err == -EINPROGRESS || err == -EBUSY)
+				return;
+		}
+	}
+
+	skcipher_request_complete(req, err);
+}
+
+static int xts_init_crypt(struct skcipher_request *req,
+			  crypto_completion_t compl)
+{
+	const struct xts_tfm_ctx *ctx =
+		crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
+	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
+	struct skcipher_request *subreq = &rctx->subreq;
+
+	if (req->cryptlen < XTS_BLOCK_SIZE)
+		return -EINVAL;
+
+	skcipher_request_set_tfm(subreq, ctx->child);
+	skcipher_request_set_callback(subreq, req->base.flags, compl, req);
+	skcipher_request_set_crypt(subreq, req->dst, req->dst,
+				   req->cryptlen & ~(XTS_BLOCK_SIZE - 1), NULL);
+
+	/* calculate first value of T */
+	crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv);
+
+	return 0;
+}
+
+static int xts_encrypt(struct skcipher_request *req)
+{
+	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
+	struct skcipher_request *subreq = &rctx->subreq;
+	int err;
+
+	err = xts_init_crypt(req, xts_encrypt_done) ?:
+	      xts_xor_tweak_pre(req, true) ?:
+	      crypto_skcipher_encrypt(subreq) ?:
+	      xts_xor_tweak_post(req, true);
+
+	if (err || likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
+		return err;
+
+	return xts_cts_final(req, crypto_skcipher_encrypt);
+}
+
+static int xts_decrypt(struct skcipher_request *req)
+{
+	struct xts_request_ctx *rctx = skcipher_request_ctx(req);
+	struct skcipher_request *subreq = &rctx->subreq;
+	int err;
+
+	err = xts_init_crypt(req, xts_decrypt_done) ?:
+	      xts_xor_tweak_pre(req, false) ?:
+	      crypto_skcipher_decrypt(subreq) ?:
+	      xts_xor_tweak_post(req, false);
+
+	if (err || likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
+		return err;
+
+	return xts_cts_final(req, crypto_skcipher_decrypt);
+}
+
+static int xts_init_tfm(struct crypto_skcipher *tfm)
+{
+	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
+	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
+	struct xts_tfm_ctx *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 xts_request_ctx));
+
+	return 0;
+}
+
+static void xts_exit_tfm(struct crypto_skcipher *tfm)
+{
+	struct xts_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
+
+	crypto_free_skcipher(ctx->child);
+	crypto_free_cipher(ctx->tweak);
+}
+
+static void xts_free_instance(struct skcipher_instance *inst)
+{
+	struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
+
+	crypto_drop_skcipher(&ictx->spawn);
+	kfree(inst);
+}
+
+static int xts_create(struct crypto_template *tmpl, struct rtattr **tb)
+{
+	struct skcipher_instance *inst;
+	struct xts_instance_ctx *ctx;
+	struct skcipher_alg *alg;
+	const char *cipher_name;
+	u32 mask;
+	int err;
+
+	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);
+	if (err)
+		return err;
+
+	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);
+
+	err = crypto_grab_skcipher(&ctx->spawn, skcipher_crypto_instance(inst),
+				   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,
+					   skcipher_crypto_instance(inst),
+					   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_free_inst;
+
+	if (crypto_skcipher_alg_ivsize(alg))
+		goto err_free_inst;
+
+	err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
+				  &alg->base);
+	if (err)
+		goto err_free_inst;
+
+	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)) {
+		int len;
+
+		len = strscpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
+		if (len < 2)
+			goto err_free_inst;
+
+		if (ctx->name[len - 1] != ')')
+			goto err_free_inst;
+
+		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_free_inst;
+		}
+	} else
+		goto err_free_inst;
+
+	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 xts_tfm_ctx);
+
+	inst->alg.init = xts_init_tfm;
+	inst->alg.exit = xts_exit_tfm;
+
+	inst->alg.setkey = xts_setkey;
+	inst->alg.encrypt = xts_encrypt;
+	inst->alg.decrypt = xts_decrypt;
+
+	inst->free = xts_free_instance;
+
+	err = skcipher_register_instance(tmpl, inst);
+	if (err) {
+err_free_inst:
+		xts_free_instance(inst);
+	}
+	return err;
+}
+
+static struct crypto_template xts_tmpl = {
+	.name = "xts",
+	.create = xts_create,
+	.module = THIS_MODULE,
+};
+
+static int __init xts_module_init(void)
+{
+	return crypto_register_template(&xts_tmpl);
+}
+
+static void __exit xts_module_exit(void)
+{
+	crypto_unregister_template(&xts_tmpl);
+}
+
+subsys_initcall(xts_module_init);
+module_exit(xts_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("XTS block cipher mode");
+MODULE_ALIAS_CRYPTO("xts");