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Diffstat (limited to 'crypto/adiantum.c')
| -rw-r--r-- | crypto/adiantum.c | 693 |
1 files changed, 693 insertions, 0 deletions
diff --git a/crypto/adiantum.c b/crypto/adiantum.c new file mode 100644 index 000000000..5ddf585ab --- /dev/null +++ b/crypto/adiantum.c @@ -0,0 +1,693 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Adiantum length-preserving encryption mode + * + * Copyright 2018 Google LLC + */ + +/* + * Adiantum is a tweakable, length-preserving encryption mode designed for fast + * and secure disk encryption, especially on CPUs without dedicated crypto + * instructions. Adiantum encrypts each sector using the XChaCha12 stream + * cipher, two passes of an ε-almost-∆-universal (ε-∆U) hash function based on + * NH and Poly1305, and an invocation of the AES-256 block cipher on a single + * 16-byte block. See the paper for details: + * + * Adiantum: length-preserving encryption for entry-level processors + * (https://eprint.iacr.org/2018/720.pdf) + * + * For flexibility, this implementation also allows other ciphers: + * + * - Stream cipher: XChaCha12 or XChaCha20 + * - Block cipher: any with a 128-bit block size and 256-bit key + */ + +#include <crypto/b128ops.h> +#include <crypto/chacha.h> +#include <crypto/internal/cipher.h> +#include <crypto/internal/poly1305.h> +#include <crypto/internal/skcipher.h> +#include <crypto/nh.h> +#include <crypto/scatterwalk.h> +#include <linux/module.h> + +/* + * Size of right-hand part of input data, in bytes; also the size of the block + * cipher's block size and the hash function's output. + */ +#define BLOCKCIPHER_BLOCK_SIZE 16 + +/* Size of the block cipher key (K_E) in bytes */ +#define BLOCKCIPHER_KEY_SIZE 32 + +/* Size of the hash key (K_H) in bytes */ +#define HASH_KEY_SIZE (2 * POLY1305_BLOCK_SIZE + NH_KEY_BYTES) + +/* + * The specification allows variable-length tweaks, but Linux's crypto API + * currently only allows algorithms to support a single length. The "natural" + * tweak length for Adiantum is 16, since that fits into one Poly1305 block for + * the best performance. But longer tweaks are useful for fscrypt, to avoid + * needing to derive per-file keys. So instead we use two blocks, or 32 bytes. + */ +#define TWEAK_SIZE 32 + +struct adiantum_instance_ctx { + struct crypto_skcipher_spawn streamcipher_spawn; + struct crypto_cipher_spawn blockcipher_spawn; +}; + +struct adiantum_tfm_ctx { + struct crypto_skcipher *streamcipher; + struct crypto_cipher *blockcipher; + struct poly1305_core_key header_hash_key; + struct poly1305_core_key msg_poly_key; + u32 nh_key[NH_KEY_WORDS]; +}; + +struct nhpoly1305_ctx { + /* Running total of polynomial evaluation */ + struct poly1305_state poly_state; + + /* Partial block buffer */ + u8 buffer[NH_MESSAGE_UNIT]; + unsigned int buflen; + + /* + * Number of bytes remaining until the current NH message reaches + * NH_MESSAGE_BYTES. When nonzero, 'nh_hash' holds the partial NH hash. + */ + unsigned int nh_remaining; + + __le64 nh_hash[NH_NUM_PASSES]; +}; + +struct adiantum_request_ctx { + /* + * skcipher sub-request size is unknown at compile-time, so it needs to + * go after the members with known sizes. + */ + union { + struct nhpoly1305_ctx hash_ctx; + struct skcipher_request streamcipher_req; + } u; +}; + +/* + * Given the XChaCha stream key K_S, derive the block cipher key K_E and the + * hash key K_H as follows: + * + * K_E || K_H || ... = XChaCha(key=K_S, nonce=1||0^191) + * + * Note that this denotes using bits from the XChaCha keystream, which here we + * get indirectly by encrypting a buffer containing all 0's. + */ +static int adiantum_setkey(struct crypto_skcipher *tfm, const u8 *key, + unsigned int keylen) +{ + struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm); + struct { + u8 iv[XCHACHA_IV_SIZE]; + u8 derived_keys[BLOCKCIPHER_KEY_SIZE + HASH_KEY_SIZE]; + struct scatterlist sg; + struct crypto_wait wait; + struct skcipher_request req; /* must be last */ + } *data; + u8 *keyp; + int err; + + /* Set the stream cipher key (K_S) */ + crypto_skcipher_clear_flags(tctx->streamcipher, CRYPTO_TFM_REQ_MASK); + crypto_skcipher_set_flags(tctx->streamcipher, + crypto_skcipher_get_flags(tfm) & + CRYPTO_TFM_REQ_MASK); + err = crypto_skcipher_setkey(tctx->streamcipher, key, keylen); + if (err) + return err; + + /* Derive the subkeys */ + data = kzalloc(sizeof(*data) + + crypto_skcipher_reqsize(tctx->streamcipher), GFP_KERNEL); + if (!data) + return -ENOMEM; + data->iv[0] = 1; + sg_init_one(&data->sg, data->derived_keys, sizeof(data->derived_keys)); + crypto_init_wait(&data->wait); + skcipher_request_set_tfm(&data->req, tctx->streamcipher); + skcipher_request_set_callback(&data->req, CRYPTO_TFM_REQ_MAY_SLEEP | + CRYPTO_TFM_REQ_MAY_BACKLOG, + crypto_req_done, &data->wait); + skcipher_request_set_crypt(&data->req, &data->sg, &data->sg, + sizeof(data->derived_keys), data->iv); + err = crypto_wait_req(crypto_skcipher_encrypt(&data->req), &data->wait); + if (err) + goto out; + keyp = data->derived_keys; + + /* Set the block cipher key (K_E) */ + crypto_cipher_clear_flags(tctx->blockcipher, CRYPTO_TFM_REQ_MASK); + crypto_cipher_set_flags(tctx->blockcipher, + crypto_skcipher_get_flags(tfm) & + CRYPTO_TFM_REQ_MASK); + err = crypto_cipher_setkey(tctx->blockcipher, keyp, + BLOCKCIPHER_KEY_SIZE); + if (err) + goto out; + keyp += BLOCKCIPHER_KEY_SIZE; + + /* Set the hash key (K_H) */ + poly1305_core_setkey(&tctx->header_hash_key, keyp); + keyp += POLY1305_BLOCK_SIZE; + poly1305_core_setkey(&tctx->msg_poly_key, keyp); + keyp += POLY1305_BLOCK_SIZE; + for (int i = 0; i < NH_KEY_WORDS; i++) + tctx->nh_key[i] = get_unaligned_le32(&keyp[i * 4]); + keyp += NH_KEY_BYTES; + WARN_ON(keyp != &data->derived_keys[ARRAY_SIZE(data->derived_keys)]); +out: + kfree_sensitive(data); + return err; +} + +/* Addition in Z/(2^{128}Z) */ +static inline void le128_add(le128 *r, const le128 *v1, const le128 *v2) +{ + u64 x = le64_to_cpu(v1->b); + u64 y = le64_to_cpu(v2->b); + + r->b = cpu_to_le64(x + y); + r->a = cpu_to_le64(le64_to_cpu(v1->a) + le64_to_cpu(v2->a) + + (x + y < x)); +} + +/* Subtraction in Z/(2^{128}Z) */ +static inline void le128_sub(le128 *r, const le128 *v1, const le128 *v2) +{ + u64 x = le64_to_cpu(v1->b); + u64 y = le64_to_cpu(v2->b); + + r->b = cpu_to_le64(x - y); + r->a = cpu_to_le64(le64_to_cpu(v1->a) - le64_to_cpu(v2->a) - + (x - y > x)); +} + +/* + * Apply the Poly1305 ε-∆U hash function to (bulk length, tweak) and save the + * result to @out. This is the calculation + * + * H_T ← Poly1305_{K_T}(bin_{128}(|L|) || T) + * + * from the procedure in section 6.4 of the Adiantum paper. The resulting value + * is reused in both the first and second hash steps. Specifically, it's added + * to the result of an independently keyed ε-∆U hash function (for equal length + * inputs only) taken over the left-hand part (the "bulk") of the message, to + * give the overall Adiantum hash of the (tweak, left-hand part) pair. + */ +static void adiantum_hash_header(struct skcipher_request *req, le128 *out) +{ + struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); + const struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm); + const unsigned int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE; + struct { + __le64 message_bits; + __le64 padding; + } header = { + .message_bits = cpu_to_le64((u64)bulk_len * 8) + }; + struct poly1305_state state; + + poly1305_core_init(&state); + + BUILD_BUG_ON(sizeof(header) % POLY1305_BLOCK_SIZE != 0); + poly1305_core_blocks(&state, &tctx->header_hash_key, + &header, sizeof(header) / POLY1305_BLOCK_SIZE, 1); + + BUILD_BUG_ON(TWEAK_SIZE % POLY1305_BLOCK_SIZE != 0); + poly1305_core_blocks(&state, &tctx->header_hash_key, req->iv, + TWEAK_SIZE / POLY1305_BLOCK_SIZE, 1); + + poly1305_core_emit(&state, NULL, out); +} + +/* Pass the next NH hash value through Poly1305 */ +static void process_nh_hash_value(struct nhpoly1305_ctx *ctx, + const struct adiantum_tfm_ctx *key) +{ + static_assert(NH_HASH_BYTES % POLY1305_BLOCK_SIZE == 0); + + poly1305_core_blocks(&ctx->poly_state, &key->msg_poly_key, ctx->nh_hash, + NH_HASH_BYTES / POLY1305_BLOCK_SIZE, 1); +} + +/* + * Feed the next portion of the message data, as a whole number of 16-byte + * "NH message units", through NH and Poly1305. Each NH hash is taken over + * 1024 bytes, except possibly the final one which is taken over a multiple of + * 16 bytes up to 1024. Also, in the case where data is passed in misaligned + * chunks, we combine partial hashes; the end result is the same either way. + */ +static void nhpoly1305_units(struct nhpoly1305_ctx *ctx, + const struct adiantum_tfm_ctx *key, + const u8 *data, size_t len) +{ + do { + unsigned int bytes; + + if (ctx->nh_remaining == 0) { + /* Starting a new NH message */ + bytes = min(len, NH_MESSAGE_BYTES); + nh(key->nh_key, data, bytes, ctx->nh_hash); + ctx->nh_remaining = NH_MESSAGE_BYTES - bytes; + } else { + /* Continuing a previous NH message */ + __le64 tmp_hash[NH_NUM_PASSES]; + unsigned int pos; + + pos = NH_MESSAGE_BYTES - ctx->nh_remaining; + bytes = min(len, ctx->nh_remaining); + nh(&key->nh_key[pos / 4], data, bytes, tmp_hash); + for (int i = 0; i < NH_NUM_PASSES; i++) + le64_add_cpu(&ctx->nh_hash[i], + le64_to_cpu(tmp_hash[i])); + ctx->nh_remaining -= bytes; + } + if (ctx->nh_remaining == 0) + process_nh_hash_value(ctx, key); + data += bytes; + len -= bytes; + } while (len); +} + +static void nhpoly1305_init(struct nhpoly1305_ctx *ctx) +{ + poly1305_core_init(&ctx->poly_state); + ctx->buflen = 0; + ctx->nh_remaining = 0; +} + +static void nhpoly1305_update(struct nhpoly1305_ctx *ctx, + const struct adiantum_tfm_ctx *key, + const u8 *data, size_t len) +{ + unsigned int bytes; + + if (ctx->buflen) { + bytes = min(len, (int)NH_MESSAGE_UNIT - ctx->buflen); + memcpy(&ctx->buffer[ctx->buflen], data, bytes); + ctx->buflen += bytes; + if (ctx->buflen < NH_MESSAGE_UNIT) + return; + nhpoly1305_units(ctx, key, ctx->buffer, NH_MESSAGE_UNIT); + ctx->buflen = 0; + data += bytes; + len -= bytes; + } + + if (len >= NH_MESSAGE_UNIT) { + bytes = round_down(len, NH_MESSAGE_UNIT); + nhpoly1305_units(ctx, key, data, bytes); + data += bytes; + len -= bytes; + } + + if (len) { + memcpy(ctx->buffer, data, len); + ctx->buflen = len; + } +} + +static void nhpoly1305_final(struct nhpoly1305_ctx *ctx, + const struct adiantum_tfm_ctx *key, le128 *out) +{ + if (ctx->buflen) { + memset(&ctx->buffer[ctx->buflen], 0, + NH_MESSAGE_UNIT - ctx->buflen); + nhpoly1305_units(ctx, key, ctx->buffer, NH_MESSAGE_UNIT); + } + + if (ctx->nh_remaining) + process_nh_hash_value(ctx, key); + + poly1305_core_emit(&ctx->poly_state, NULL, out); +} + +/* + * Hash the left-hand part (the "bulk") of the message as follows: + * + * H_L ← Poly1305_{K_L}(NH_{K_N}(pad_{128}(L))) + * + * See section 6.4 of the Adiantum paper. This is an ε-almost-∆-universal + * (ε-∆U) hash function for equal-length inputs over Z/(2^{128}Z), where the "∆" + * operation is addition. It hashes 1024-byte chunks of the input with the NH + * hash function, reducing the input length by 32x. The resulting NH hashes are + * evaluated as a polynomial in GF(2^{130}-5), like in the Poly1305 MAC. Note + * that the polynomial evaluation by itself would suffice to achieve the ε-∆U + * property; NH is used for performance since it's much faster than Poly1305. + */ +static void adiantum_hash_message(struct skcipher_request *req, + struct scatterlist *sgl, le128 *out) +{ + struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); + const struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm); + struct adiantum_request_ctx *rctx = skcipher_request_ctx(req); + unsigned int len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE; + struct scatter_walk walk; + + nhpoly1305_init(&rctx->u.hash_ctx); + scatterwalk_start(&walk, sgl); + while (len) { + unsigned int n = scatterwalk_next(&walk, len); + + nhpoly1305_update(&rctx->u.hash_ctx, tctx, walk.addr, n); + scatterwalk_done_src(&walk, n); + len -= n; + } + nhpoly1305_final(&rctx->u.hash_ctx, tctx, out); +} + +static int adiantum_crypt(struct skcipher_request *req, bool enc) +{ + struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); + const struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm); + struct adiantum_request_ctx *rctx = skcipher_request_ctx(req); + const unsigned int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE; + struct scatterlist *src = req->src, *dst = req->dst; + /* + * Buffer for right-hand part of data, i.e. + * + * P_L => P_M => C_M => C_R when encrypting, or + * C_R => C_M => P_M => P_L when decrypting. + * + * Also used to build the IV for the stream cipher. + */ + union { + u8 bytes[XCHACHA_IV_SIZE]; + __le32 words[XCHACHA_IV_SIZE / sizeof(__le32)]; + le128 bignum; /* interpret as element of Z/(2^{128}Z) */ + } rbuf; + le128 header_hash, msg_hash; + unsigned int stream_len; + int err; + + if (req->cryptlen < BLOCKCIPHER_BLOCK_SIZE) + return -EINVAL; + + /* + * First hash step + * enc: P_M = P_R + H_{K_H}(T, P_L) + * dec: C_M = C_R + H_{K_H}(T, C_L) + */ + adiantum_hash_header(req, &header_hash); + if (src->length >= req->cryptlen && + src->offset + req->cryptlen <= PAGE_SIZE) { + /* Fast path for single-page source */ + void *virt = kmap_local_page(sg_page(src)) + src->offset; + + nhpoly1305_init(&rctx->u.hash_ctx); + nhpoly1305_update(&rctx->u.hash_ctx, tctx, virt, bulk_len); + nhpoly1305_final(&rctx->u.hash_ctx, tctx, &msg_hash); + memcpy(&rbuf.bignum, virt + bulk_len, sizeof(le128)); + kunmap_local(virt); + } else { + /* Slow path that works for any source scatterlist */ + adiantum_hash_message(req, src, &msg_hash); + memcpy_from_sglist(&rbuf.bignum, src, bulk_len, sizeof(le128)); + } + le128_add(&rbuf.bignum, &rbuf.bignum, &header_hash); + le128_add(&rbuf.bignum, &rbuf.bignum, &msg_hash); + + /* If encrypting, encrypt P_M with the block cipher to get C_M */ + if (enc) + crypto_cipher_encrypt_one(tctx->blockcipher, rbuf.bytes, + rbuf.bytes); + + /* Initialize the rest of the XChaCha IV (first part is C_M) */ + BUILD_BUG_ON(BLOCKCIPHER_BLOCK_SIZE != 16); + BUILD_BUG_ON(XCHACHA_IV_SIZE != 32); /* nonce || stream position */ + rbuf.words[4] = cpu_to_le32(1); + rbuf.words[5] = 0; + rbuf.words[6] = 0; + rbuf.words[7] = 0; + + /* + * XChaCha needs to be done on all the data except the last 16 bytes; + * for disk encryption that usually means 4080 or 496 bytes. But ChaCha + * implementations tend to be most efficient when passed a whole number + * of 64-byte ChaCha blocks, or sometimes even a multiple of 256 bytes. + * And here it doesn't matter whether the last 16 bytes are written to, + * as the second hash step will overwrite them. Thus, round the XChaCha + * length up to the next 64-byte boundary if possible. + */ + stream_len = bulk_len; + if (round_up(stream_len, CHACHA_BLOCK_SIZE) <= req->cryptlen) + stream_len = round_up(stream_len, CHACHA_BLOCK_SIZE); + + skcipher_request_set_tfm(&rctx->u.streamcipher_req, tctx->streamcipher); + skcipher_request_set_crypt(&rctx->u.streamcipher_req, req->src, + req->dst, stream_len, &rbuf); + skcipher_request_set_callback(&rctx->u.streamcipher_req, + req->base.flags, NULL, NULL); + err = crypto_skcipher_encrypt(&rctx->u.streamcipher_req); + if (err) + return err; + + /* If decrypting, decrypt C_M with the block cipher to get P_M */ + if (!enc) + crypto_cipher_decrypt_one(tctx->blockcipher, rbuf.bytes, + rbuf.bytes); + + /* + * Second hash step + * enc: C_R = C_M - H_{K_H}(T, C_L) + * dec: P_R = P_M - H_{K_H}(T, P_L) + */ + le128_sub(&rbuf.bignum, &rbuf.bignum, &header_hash); + if (dst->length >= req->cryptlen && + dst->offset + req->cryptlen <= PAGE_SIZE) { + /* Fast path for single-page destination */ + struct page *page = sg_page(dst); + void *virt = kmap_local_page(page) + dst->offset; + + nhpoly1305_init(&rctx->u.hash_ctx); + nhpoly1305_update(&rctx->u.hash_ctx, tctx, virt, bulk_len); + nhpoly1305_final(&rctx->u.hash_ctx, tctx, &msg_hash); + le128_sub(&rbuf.bignum, &rbuf.bignum, &msg_hash); + memcpy(virt + bulk_len, &rbuf.bignum, sizeof(le128)); + flush_dcache_page(page); + kunmap_local(virt); + } else { + /* Slow path that works for any destination scatterlist */ + adiantum_hash_message(req, dst, &msg_hash); + le128_sub(&rbuf.bignum, &rbuf.bignum, &msg_hash); + memcpy_to_sglist(dst, bulk_len, &rbuf.bignum, sizeof(le128)); + } + return 0; +} + +static int adiantum_encrypt(struct skcipher_request *req) +{ + return adiantum_crypt(req, true); +} + +static int adiantum_decrypt(struct skcipher_request *req) +{ + return adiantum_crypt(req, false); +} + +static int adiantum_init_tfm(struct crypto_skcipher *tfm) +{ + struct skcipher_instance *inst = skcipher_alg_instance(tfm); + struct adiantum_instance_ctx *ictx = skcipher_instance_ctx(inst); + struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm); + struct crypto_skcipher *streamcipher; + struct crypto_cipher *blockcipher; + int err; + + streamcipher = crypto_spawn_skcipher(&ictx->streamcipher_spawn); + if (IS_ERR(streamcipher)) + return PTR_ERR(streamcipher); + + blockcipher = crypto_spawn_cipher(&ictx->blockcipher_spawn); + if (IS_ERR(blockcipher)) { + err = PTR_ERR(blockcipher); + goto err_free_streamcipher; + } + + tctx->streamcipher = streamcipher; + tctx->blockcipher = blockcipher; + + BUILD_BUG_ON(offsetofend(struct adiantum_request_ctx, u) != + sizeof(struct adiantum_request_ctx)); + crypto_skcipher_set_reqsize( + tfm, max(sizeof(struct adiantum_request_ctx), + offsetofend(struct adiantum_request_ctx, + u.streamcipher_req) + + crypto_skcipher_reqsize(streamcipher))); + return 0; + +err_free_streamcipher: + crypto_free_skcipher(streamcipher); + return err; +} + +static void adiantum_exit_tfm(struct crypto_skcipher *tfm) +{ + struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm); + + crypto_free_skcipher(tctx->streamcipher); + crypto_free_cipher(tctx->blockcipher); +} + +static void adiantum_free_instance(struct skcipher_instance *inst) +{ + struct adiantum_instance_ctx *ictx = skcipher_instance_ctx(inst); + + crypto_drop_skcipher(&ictx->streamcipher_spawn); + crypto_drop_cipher(&ictx->blockcipher_spawn); + kfree(inst); +} + +/* + * Check for a supported set of inner algorithms. + * See the comment at the beginning of this file. + */ +static bool +adiantum_supported_algorithms(struct skcipher_alg_common *streamcipher_alg, + struct crypto_alg *blockcipher_alg) +{ + if (strcmp(streamcipher_alg->base.cra_name, "xchacha12") != 0 && + strcmp(streamcipher_alg->base.cra_name, "xchacha20") != 0) + return false; + + if (blockcipher_alg->cra_cipher.cia_min_keysize > BLOCKCIPHER_KEY_SIZE || + blockcipher_alg->cra_cipher.cia_max_keysize < BLOCKCIPHER_KEY_SIZE) + return false; + if (blockcipher_alg->cra_blocksize != BLOCKCIPHER_BLOCK_SIZE) + return false; + + return true; +} + +static int adiantum_create(struct crypto_template *tmpl, struct rtattr **tb) +{ + u32 mask; + struct skcipher_instance *inst; + struct adiantum_instance_ctx *ictx; + struct skcipher_alg_common *streamcipher_alg; + struct crypto_alg *blockcipher_alg; + int err; + + err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask); + if (err) + return err; + + inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL); + if (!inst) + return -ENOMEM; + ictx = skcipher_instance_ctx(inst); + + /* Stream cipher, e.g. "xchacha12" */ + err = crypto_grab_skcipher(&ictx->streamcipher_spawn, + skcipher_crypto_instance(inst), + crypto_attr_alg_name(tb[1]), 0, + mask | CRYPTO_ALG_ASYNC /* sync only */); + if (err) + goto err_free_inst; + streamcipher_alg = crypto_spawn_skcipher_alg_common(&ictx->streamcipher_spawn); + + /* Block cipher, e.g. "aes" */ + err = crypto_grab_cipher(&ictx->blockcipher_spawn, + skcipher_crypto_instance(inst), + crypto_attr_alg_name(tb[2]), 0, mask); + if (err) + goto err_free_inst; + blockcipher_alg = crypto_spawn_cipher_alg(&ictx->blockcipher_spawn); + + /* + * Originally there was an optional third parameter, for requesting a + * specific implementation of "nhpoly1305" for message hashing. This is + * no longer supported. The best implementation is just always used. + */ + if (crypto_attr_alg_name(tb[3]) != ERR_PTR(-ENOENT)) { + err = -ENOENT; + goto err_free_inst; + } + + /* Check the set of algorithms */ + if (!adiantum_supported_algorithms(streamcipher_alg, blockcipher_alg)) { + pr_warn("Unsupported Adiantum instantiation: (%s,%s)\n", + streamcipher_alg->base.cra_name, + blockcipher_alg->cra_name); + err = -EINVAL; + goto err_free_inst; + } + + /* Instance fields */ + + err = -ENAMETOOLONG; + if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, + "adiantum(%s,%s)", streamcipher_alg->base.cra_name, + blockcipher_alg->cra_name) >= CRYPTO_MAX_ALG_NAME) + goto err_free_inst; + if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME, + "adiantum(%s,%s)", streamcipher_alg->base.cra_driver_name, + blockcipher_alg->cra_driver_name) >= CRYPTO_MAX_ALG_NAME) + goto err_free_inst; + + inst->alg.base.cra_blocksize = BLOCKCIPHER_BLOCK_SIZE; + inst->alg.base.cra_ctxsize = sizeof(struct adiantum_tfm_ctx); + inst->alg.base.cra_alignmask = streamcipher_alg->base.cra_alignmask; + /* + * The block cipher is only invoked once per message, so for long + * messages (e.g. sectors for disk encryption) its performance doesn't + * matter as much as that of the stream cipher. Thus, weigh the block + * cipher's ->cra_priority less. + */ + inst->alg.base.cra_priority = (4 * streamcipher_alg->base.cra_priority + + blockcipher_alg->cra_priority) / + 5; + + inst->alg.setkey = adiantum_setkey; + inst->alg.encrypt = adiantum_encrypt; + inst->alg.decrypt = adiantum_decrypt; + inst->alg.init = adiantum_init_tfm; + inst->alg.exit = adiantum_exit_tfm; + inst->alg.min_keysize = streamcipher_alg->min_keysize; + inst->alg.max_keysize = streamcipher_alg->max_keysize; + inst->alg.ivsize = TWEAK_SIZE; + + inst->free = adiantum_free_instance; + + err = skcipher_register_instance(tmpl, inst); + if (err) { +err_free_inst: + adiantum_free_instance(inst); + } + return err; +} + +/* adiantum(streamcipher_name, blockcipher_name) */ +static struct crypto_template adiantum_tmpl = { + .name = "adiantum", + .create = adiantum_create, + .module = THIS_MODULE, +}; + +static int __init adiantum_module_init(void) +{ + return crypto_register_template(&adiantum_tmpl); +} + +static void __exit adiantum_module_exit(void) +{ + crypto_unregister_template(&adiantum_tmpl); +} + +module_init(adiantum_module_init); +module_exit(adiantum_module_exit); + +MODULE_DESCRIPTION("Adiantum length-preserving encryption mode"); +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("Eric Biggers <ebiggers@google.com>"); +MODULE_ALIAS_CRYPTO("adiantum"); +MODULE_IMPORT_NS("CRYPTO_INTERNAL"); |