| // 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)) { |
| unsigned len; |
| |
| len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name)); |
| if (len < 2 || len >= sizeof(ctx->name)) |
| 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"); |