summaryrefslogtreecommitdiffstats
path: root/crypto/xts.c
diff options
context:
space:
mode:
Diffstat (limited to 'crypto/xts.c')
-rw-r--r--crypto/xts.c469
1 files changed, 469 insertions, 0 deletions
diff --git a/crypto/xts.c b/crypto/xts.c
new file mode 100644
index 000000000..b05020657
--- /dev/null
+++ b/crypto/xts.c
@@ -0,0 +1,469 @@
+// 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/cipher.h>
+#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");
+MODULE_IMPORT_NS(CRYPTO_INTERNAL);
+MODULE_SOFTDEP("pre: ecb");