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Diffstat (limited to 'crypto/heh.c')
| -rw-r--r-- | crypto/heh.c | 899 |
1 files changed, 899 insertions, 0 deletions
diff --git a/crypto/heh.c b/crypto/heh.c new file mode 100644 index 000000000000..48a284cecaa2 --- /dev/null +++ b/crypto/heh.c @@ -0,0 +1,899 @@ +/* + * HEH: Hash-Encrypt-Hash mode + * + * Copyright (c) 2016 Google Inc. + * + * Authors: + * Alex Cope <alexcope@google.com> + * Eric Biggers <ebiggers@google.com> + */ + +/* + * Hash-Encrypt-Hash (HEH) is a proposed block cipher mode of operation which + * extends the strong pseudo-random permutation (SPRP) property of block ciphers + * (e.g. AES) to arbitrary length input strings. It uses two keyed invertible + * hash functions with a layer of ECB encryption applied in-between. The + * algorithm is specified by the following Internet Draft: + * + * https://tools.ietf.org/html/draft-cope-heh-01 + * + * Although HEH can be used as either a regular symmetric cipher or as an AEAD, + * currently this module only provides it as a symmetric cipher. Additionally, + * only 16-byte nonces are supported. + */ + +#include <crypto/gf128mul.h> +#include <crypto/internal/hash.h> +#include <crypto/internal/skcipher.h> +#include <crypto/scatterwalk.h> +#include <crypto/skcipher.h> +#include "internal.h" + +/* + * The block size is the size of GF(2^128) elements and also the required block + * size of the underlying block cipher. + */ +#define HEH_BLOCK_SIZE 16 + +struct heh_instance_ctx { + struct crypto_shash_spawn cmac; + struct crypto_skcipher_spawn ecb; +}; + +struct heh_tfm_ctx { + struct crypto_shash *cmac; + struct crypto_ablkcipher *ecb; + struct gf128mul_4k *tau_key; +}; + +struct heh_cmac_data { + u8 nonce[HEH_BLOCK_SIZE]; + __le32 nonce_length; + __le32 aad_length; + __le32 message_length; + __le32 padding; +}; + +struct heh_req_ctx { /* aligned to alignmask */ + be128 beta1_key; + be128 beta2_key; + union { + struct { + struct heh_cmac_data data; + struct shash_desc desc; + /* + crypto_shash_descsize(cmac) */ + } cmac; + struct { + u8 keystream[HEH_BLOCK_SIZE]; + u8 tmp[HEH_BLOCK_SIZE]; + struct scatterlist tmp_sgl[2]; + struct ablkcipher_request req; + /* + crypto_ablkcipher_reqsize(ecb) */ + } ecb; + } u; +}; + +/* + * Get the offset in bytes to the last full block, or equivalently the length of + * all full blocks excluding the last + */ +static inline unsigned int get_tail_offset(unsigned int len) +{ + len -= len % HEH_BLOCK_SIZE; + return len - HEH_BLOCK_SIZE; +} + +static inline struct heh_req_ctx *heh_req_ctx(struct ablkcipher_request *req) +{ + unsigned int alignmask = crypto_ablkcipher_alignmask( + crypto_ablkcipher_reqtfm(req)); + + return (void *)PTR_ALIGN((u8 *)ablkcipher_request_ctx(req), + alignmask + 1); +} + +static inline void async_done(struct crypto_async_request *areq, int err, + int (*next_step)(struct ablkcipher_request *, + u32)) +{ + struct ablkcipher_request *req = areq->data; + + if (err) + goto out; + + err = next_step(req, req->base.flags & ~CRYPTO_TFM_REQ_MAY_SLEEP); + if (err == -EINPROGRESS || + (err == -EBUSY && (req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))) + return; +out: + ablkcipher_request_complete(req, err); +} + +/* + * Generate the per-message "beta" keys used by the hashing layers of HEH. The + * first beta key is the CMAC of the nonce, the additional authenticated data + * (AAD), and the lengths in bytes of the nonce, AAD, and message. The nonce + * and AAD are each zero-padded to the next 16-byte block boundary, and the + * lengths are serialized as 4-byte little endian integers and zero-padded to + * the next 16-byte block boundary. + * The second beta key is the first one interpreted as an element in GF(2^128) + * and multiplied by x. + * + * Note that because the nonce and AAD may, in general, be variable-length, the + * key generation must be done by a pseudo-random function (PRF) on + * variable-length inputs. CBC-MAC does not satisfy this, as it is only a PRF + * on fixed-length inputs. CMAC remedies this flaw. Including the lengths of + * the nonce, AAD, and message is also critical to avoid collisions. + * + * That being said, this implementation does not yet operate as an AEAD and + * therefore there is never any AAD, nor are variable-length nonces supported. + */ +static int generate_betas(struct ablkcipher_request *req, + be128 *beta1_key, be128 *beta2_key) +{ + struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req); + struct heh_tfm_ctx *ctx = crypto_ablkcipher_ctx(tfm); + struct heh_req_ctx *rctx = heh_req_ctx(req); + struct heh_cmac_data *data = &rctx->u.cmac.data; + struct shash_desc *desc = &rctx->u.cmac.desc; + int err; + + BUILD_BUG_ON(sizeof(*data) != 2 * HEH_BLOCK_SIZE); + memcpy(data->nonce, req->info, HEH_BLOCK_SIZE); + data->nonce_length = cpu_to_le32(HEH_BLOCK_SIZE); + data->aad_length = cpu_to_le32(0); + data->message_length = cpu_to_le32(req->nbytes); + data->padding = cpu_to_le32(0); + + desc->tfm = ctx->cmac; + desc->flags = req->base.flags; + + err = crypto_shash_digest(desc, (const u8 *)data, sizeof(*data), + (u8 *)beta1_key); + if (err) + return err; + + gf128mul_x_ble(beta2_key, beta1_key); + return 0; +} + +/* + * Evaluation of a polynomial over GF(2^128) using Horner's rule. The + * polynomial is evaluated at 'point'. The polynomial's coefficients are taken + * from 'coeffs_sgl' and are for terms with consecutive descending degree ending + * at degree 1. 'bytes_of_coeffs' is 16 times the number of terms. + */ +static be128 evaluate_polynomial(struct gf128mul_4k *point, + struct scatterlist *coeffs_sgl, + unsigned int bytes_of_coeffs) +{ + be128 value = {0}; + struct sg_mapping_iter miter; + unsigned int remaining = bytes_of_coeffs; + unsigned int needed = 0; + + sg_miter_start(&miter, coeffs_sgl, sg_nents(coeffs_sgl), + SG_MITER_FROM_SG | SG_MITER_ATOMIC); + while (remaining) { + be128 coeff; + const u8 *src; + unsigned int srclen; + u8 *dst = (u8 *)&value; + + /* + * Note: scatterlist elements are not necessarily evenly + * divisible into blocks, nor are they necessarily aligned to + * __alignof__(be128). + */ + sg_miter_next(&miter); + + src = miter.addr; + srclen = min_t(unsigned int, miter.length, remaining); + remaining -= srclen; + + if (needed) { + unsigned int n = min(srclen, needed); + u8 *pos = dst + (HEH_BLOCK_SIZE - needed); + + needed -= n; + srclen -= n; + + while (n--) + *pos++ ^= *src++; + + if (!needed) + gf128mul_4k_ble(&value, point); + } + + while (srclen >= HEH_BLOCK_SIZE) { + memcpy(&coeff, src, HEH_BLOCK_SIZE); + be128_xor(&value, &value, &coeff); + gf128mul_4k_ble(&value, point); + src += HEH_BLOCK_SIZE; + srclen -= HEH_BLOCK_SIZE; + } + + if (srclen) { + needed = HEH_BLOCK_SIZE - srclen; + do { + *dst++ ^= *src++; + } while (--srclen); + } + } + sg_miter_stop(&miter); + return value; +} + +/* + * Split the message into 16 byte blocks, padding out the last block, and use + * the blocks as coefficients in the evaluation of a polynomial over GF(2^128) + * at the secret point 'tau_key'. For ease of implementing the higher-level + * heh_hash_inv() function, the constant and degree-1 coefficients are swapped + * if there is a partial block. + * + * Mathematically, compute: + * if (no partial block) + * k^{N-1} * m_0 + ... + k * m_{N-2} + m_{N-1} + * else if (partial block) + * k^N * m_0 + ... + k^2 * m_{N-2} + k * m_N + m_{N-1} + * + * where: + * t is tau_key + * N is the number of full blocks in the message + * m_i is the i-th full block in the message for i = 0 to N-1 inclusive + * m_N is the partial block of the message zero-padded up to 16 bytes + */ +static be128 poly_hash(struct crypto_ablkcipher *tfm, struct scatterlist *sgl, + unsigned int len) +{ + struct heh_tfm_ctx *ctx = crypto_ablkcipher_ctx(tfm); + unsigned int tail_offset = get_tail_offset(len); + unsigned int tail_len = len - tail_offset; + be128 hash; + be128 tail[2]; + + /* Handle all full blocks except the last */ + hash = evaluate_polynomial(ctx->tau_key, sgl, tail_offset); + + /* Handle the last full block and the partial block */ + scatterwalk_map_and_copy(tail, sgl, tail_offset, tail_len, 0); + + if (tail_len != HEH_BLOCK_SIZE) { + /* handle the partial block */ + memset((u8 *)tail + tail_len, 0, sizeof(tail) - tail_len); + be128_xor(&hash, &hash, &tail[1]); + gf128mul_4k_ble(&hash, ctx->tau_key); + } + be128_xor(&hash, &hash, &tail[0]); + return hash; +} + +/* + * Transform all full blocks except the last. + * This is used by both the hash and inverse hash phases. + */ +static int heh_tfm_blocks(struct ablkcipher_request *req, + struct scatterlist *src_sgl, + struct scatterlist *dst_sgl, unsigned int len, + const be128 *hash, const be128 *beta_key) +{ + struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req); + struct blkcipher_desc desc = { .flags = req->base.flags }; + struct blkcipher_walk walk; + be128 e = *beta_key; + int err; + unsigned int nbytes; + + blkcipher_walk_init(&walk, dst_sgl, src_sgl, len); + + err = blkcipher_ablkcipher_walk_virt(&desc, &walk, tfm); + + while ((nbytes = walk.nbytes)) { + const be128 *src = (be128 *)walk.src.virt.addr; + be128 *dst = (be128 *)walk.dst.virt.addr; + + do { + gf128mul_x_ble(&e, &e); + be128_xor(dst, src, hash); + be128_xor(dst, dst, &e); + src++; + dst++; + } while ((nbytes -= HEH_BLOCK_SIZE) >= HEH_BLOCK_SIZE); + err = blkcipher_walk_done(&desc, &walk, nbytes); + } + return err; +} + +/* + * The hash phase of HEH. Given a message, compute: + * + * (m_0 + H, ..., m_{N-2} + H, H, m_N) + (xb, x^2b, ..., x^{N-1}b, b, 0) + * + * where: + * N is the number of full blocks in the message + * m_i is the i-th full block in the message for i = 0 to N-1 inclusive + * m_N is the unpadded partial block, possibly empty + * H is the poly_hash() of the message, keyed by tau_key + * b is beta_key + * x is the element x in our representation of GF(2^128) + * + * Note that the partial block remains unchanged, but it does affect the result + * of poly_hash() and therefore the transformation of all the full blocks. + */ +static int heh_hash(struct ablkcipher_request *req, const be128 *beta_key) +{ + be128 hash; + struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req); + unsigned int tail_offset = get_tail_offset(req->nbytes); + unsigned int partial_len = req->nbytes % HEH_BLOCK_SIZE; + int err; + + /* poly_hash() the full message including the partial block */ + hash = poly_hash(tfm, req->src, req->nbytes); + + /* Transform all full blocks except the last */ + err = heh_tfm_blocks(req, req->src, req->dst, tail_offset, &hash, + beta_key); + if (err) + return err; + + /* Set the last full block to hash XOR beta_key */ + be128_xor(&hash, &hash, beta_key); + scatterwalk_map_and_copy(&hash, req->dst, tail_offset, HEH_BLOCK_SIZE, + 1); + + /* Copy the partial block if needed */ + if (partial_len != 0 && req->src != req->dst) { + unsigned int offs = tail_offset + HEH_BLOCK_SIZE; + + scatterwalk_map_and_copy(&hash, req->src, offs, partial_len, 0); + scatterwalk_map_and_copy(&hash, req->dst, offs, partial_len, 1); + } + return 0; +} + +/* + * The inverse hash phase of HEH. This undoes the result of heh_hash(). + */ +static int heh_hash_inv(struct ablkcipher_request *req, const be128 *beta_key) +{ + be128 hash; + be128 tmp; + struct scatterlist tmp_sgl[2]; + struct scatterlist *tail_sgl; + unsigned int len = req->nbytes; + unsigned int tail_offset = get_tail_offset(len); + struct scatterlist *sgl = req->dst; + struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req); + int err; + + /* + * The last full block was computed as hash XOR beta_key, so XOR it with + * beta_key to recover hash. + */ + tail_sgl = scatterwalk_ffwd(tmp_sgl, sgl, tail_offset); + scatterwalk_map_and_copy(&hash, tail_sgl, 0, HEH_BLOCK_SIZE, 0); + be128_xor(&hash, &hash, beta_key); + + /* Transform all full blocks except the last */ + err = heh_tfm_blocks(req, sgl, sgl, tail_offset, &hash, beta_key); + if (err) + return err; + + /* + * Recover the last full block. We know 'hash', i.e. the poly_hash() of + * the the original message. The last full block was the constant term + * of the polynomial. To recover the last full block, temporarily zero + * it, compute the poly_hash(), and take the difference from 'hash'. + */ + memset(&tmp, 0, sizeof(tmp)); + scatterwalk_map_and_copy(&tmp, tail_sgl, 0, HEH_BLOCK_SIZE, 1); + tmp = poly_hash(tfm, sgl, len); + be128_xor(&tmp, &tmp, &hash); + scatterwalk_map_and_copy(&tmp, tail_sgl, 0, HEH_BLOCK_SIZE, 1); + return 0; +} + +static int heh_hash_inv_step(struct ablkcipher_request *req, u32 flags) +{ + struct heh_req_ctx *rctx = heh_req_ctx(req); + + return heh_hash_inv(req, &rctx->beta2_key); +} + +static int heh_ecb_step_3(struct ablkcipher_request *req, u32 flags) +{ + struct heh_req_ctx *rctx = heh_req_ctx(req); + u8 partial_block[HEH_BLOCK_SIZE] __aligned(__alignof__(u32)); + unsigned int tail_offset = get_tail_offset(req->nbytes); + unsigned int partial_offset = tail_offset + HEH_BLOCK_SIZE; + unsigned int partial_len = req->nbytes - partial_offset; + + /* + * Extract the pad in req->dst at tail_offset, and xor the partial block + * with it to create encrypted partial block + */ + scatterwalk_map_and_copy(rctx->u.ecb.keystream, req->dst, tail_offset, + HEH_BLOCK_SIZE, 0); + scatterwalk_map_and_copy(partial_block, req->dst, partial_offset, + partial_len, 0); + crypto_xor(partial_block, rctx->u.ecb.keystream, partial_len); + + /* + * Store the encrypted final block and partial block back in dst_sg + */ + scatterwalk_map_and_copy(&rctx->u.ecb.tmp, req->dst, tail_offset, + HEH_BLOCK_SIZE, 1); + scatterwalk_map_and_copy(partial_block, req->dst, partial_offset, + partial_len, 1); + + return heh_hash_inv_step(req, flags); +} + +static void heh_ecb_step_2_done(struct crypto_async_request *areq, int err) +{ + return async_done(areq, err, heh_ecb_step_3); +} + +static int heh_ecb_step_2(struct ablkcipher_request *req, u32 flags) +{ + struct heh_req_ctx *rctx = heh_req_ctx(req); + unsigned int partial_len = req->nbytes % HEH_BLOCK_SIZE; + struct scatterlist *tmp_sgl; + int err; + unsigned int tail_offset = get_tail_offset(req->nbytes); + + if (partial_len == 0) + return heh_hash_inv_step(req, flags); + + /* + * Extract the final full block, store it in tmp, and then xor that with + * the value saved in u.ecb.keystream + */ + scatterwalk_map_and_copy(rctx->u.ecb.tmp, req->dst, tail_offset, + HEH_BLOCK_SIZE, 0); + crypto_xor(rctx->u.ecb.keystream, rctx->u.ecb.tmp, HEH_BLOCK_SIZE); + + /* + * Encrypt the value in rctx->u.ecb.keystream to create the pad for the + * partial block. + * We cannot encrypt stack buffers, so re-use the dst_sg to do this + * encryption to avoid a malloc. The value at tail_offset is stored in + * tmp, and will be restored later. + */ + scatterwalk_map_and_copy(rctx->u.ecb.keystream, req->dst, tail_offset, + HEH_BLOCK_SIZE, 1); + tmp_sgl = scatterwalk_ffwd(rctx->u.ecb.tmp_sgl, req->dst, tail_offset); + ablkcipher_request_set_callback(&rctx->u.ecb.req, flags, + heh_ecb_step_2_done, req); + ablkcipher_request_set_crypt(&rctx->u.ecb.req, tmp_sgl, tmp_sgl, + HEH_BLOCK_SIZE, NULL); + err = crypto_ablkcipher_encrypt(&rctx->u.ecb.req); + if (err) + return err; + return heh_ecb_step_3(req, flags); +} + +static void heh_ecb_full_done(struct crypto_async_request *areq, int err) +{ + return async_done(areq, err, heh_ecb_step_2); +} + +/* + * The encrypt phase of HEH. This uses ECB encryption, with special handling + * for the partial block at the end if any. The source data is already in + * req->dst, so the encryption happens in-place. + * + * After the encrypt phase we continue on to the inverse hash phase. The + * functions calls are chained to support asynchronous ECB algorithms. + */ +static int heh_ecb(struct ablkcipher_request *req, bool decrypt) +{ + struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req); + struct heh_tfm_ctx *ctx = crypto_ablkcipher_ctx(tfm); + struct heh_req_ctx *rctx = heh_req_ctx(req); + struct ablkcipher_request *ecb_req = &rctx->u.ecb.req; + unsigned int tail_offset = get_tail_offset(req->nbytes); + unsigned int full_len = tail_offset + HEH_BLOCK_SIZE; + int err; + + /* + * Save the last full block before it is encrypted/decrypted. This will + * be used later to encrypt/decrypt the partial block + */ + scatterwalk_map_and_copy(rctx->u.ecb.keystream, req->dst, tail_offset, + HEH_BLOCK_SIZE, 0); + + /* Encrypt/decrypt all full blocks */ + ablkcipher_request_set_tfm(ecb_req, ctx->ecb); + ablkcipher_request_set_callback(ecb_req, req->base.flags, + heh_ecb_full_done, req); + ablkcipher_request_set_crypt(ecb_req, req->dst, req->dst, full_len, + NULL); + if (decrypt) + err = crypto_ablkcipher_decrypt(ecb_req); + else + err = crypto_ablkcipher_encrypt(ecb_req); + if (err) + return err; + + return heh_ecb_step_2(req, req->base.flags); +} + +static int heh_crypt(struct ablkcipher_request *req, bool decrypt) +{ + struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req); + struct heh_tfm_ctx *ctx = crypto_ablkcipher_ctx(tfm); + struct heh_req_ctx *rctx = heh_req_ctx(req); + int err; + + /* Inputs must be at least one full block */ + if (req->nbytes < HEH_BLOCK_SIZE) + return -EINVAL; + + /* Key must have been set */ + if (!ctx->tau_key) + return -ENOKEY; + err = generate_betas(req, &rctx->beta1_key, &rctx->beta2_key); + if (err) + return err; + + if (decrypt) + swap(rctx->beta1_key, rctx->beta2_key); + + err = heh_hash(req, &rctx->beta1_key); + if (err) + return err; + + return heh_ecb(req, decrypt); +} + +static int heh_encrypt(struct ablkcipher_request *req) +{ + return heh_crypt(req, false); +} + +static int heh_decrypt(struct ablkcipher_request *req) +{ + return heh_crypt(req, true); +} + +static int heh_setkey(struct crypto_ablkcipher *parent, const u8 *key, + unsigned int keylen) +{ + struct heh_tfm_ctx *ctx = crypto_ablkcipher_ctx(parent); + struct crypto_shash *cmac = ctx->cmac; + struct crypto_ablkcipher *ecb = ctx->ecb; + SHASH_DESC_ON_STACK(desc, cmac); + u8 *derived_keys; + u8 digest[HEH_BLOCK_SIZE]; + unsigned int i; + int err; + + /* set prf_key = key */ + crypto_shash_clear_flags(cmac, CRYPTO_TFM_REQ_MASK); + crypto_shash_set_flags(cmac, crypto_ablkcipher_get_flags(parent) & + CRYPTO_TFM_REQ_MASK); + err = crypto_shash_setkey(cmac, key, keylen); + crypto_ablkcipher_set_flags(parent, crypto_shash_get_flags(cmac) & + CRYPTO_TFM_RES_MASK); + if (err) + return err; + + /* + * Generate tau_key and ecb_key as follows: + * tau_key = cmac(prf_key, 0x00...01) + * ecb_key = cmac(prf_key, 0x00...02) || cmac(prf_key, 0x00...03) || ... + * truncated to keylen bytes + */ + derived_keys = kzalloc(round_up(HEH_BLOCK_SIZE + keylen, + HEH_BLOCK_SIZE), GFP_KERNEL); + if (!derived_keys) + return -ENOMEM; + desc->tfm = cmac; + desc->flags = (crypto_shash_get_flags(cmac) & CRYPTO_TFM_REQ_MASK); + for (i = 0; i < keylen + HEH_BLOCK_SIZE; i += HEH_BLOCK_SIZE) { + derived_keys[i + HEH_BLOCK_SIZE - 1] = + 0x01 + i / HEH_BLOCK_SIZE; + err = crypto_shash_digest(desc, derived_keys + i, + HEH_BLOCK_SIZE, digest); + if (err) + goto out; + memcpy(derived_keys + i, digest, HEH_BLOCK_SIZE); + } + + if (ctx->tau_key) + gf128mul_free_4k(ctx->tau_key); + err = -ENOMEM; + ctx->tau_key = gf128mul_init_4k_ble((const be128 *)derived_keys); + if (!ctx->tau_key) + goto out; + + crypto_ablkcipher_clear_flags(ecb, CRYPTO_TFM_REQ_MASK); + crypto_ablkcipher_set_flags(ecb, crypto_ablkcipher_get_flags(parent) & + CRYPTO_TFM_REQ_MASK); + err = crypto_ablkcipher_setkey(ecb, derived_keys + HEH_BLOCK_SIZE, + keylen); + crypto_ablkcipher_set_flags(parent, crypto_ablkcipher_get_flags(ecb) & + CRYPTO_TFM_RES_MASK); +out: + kzfree(derived_keys); + return err; +} + +static int heh_init_tfm(struct crypto_tfm *tfm) +{ + struct crypto_instance *inst = crypto_tfm_alg_instance(tfm); + struct heh_instance_ctx *ictx = crypto_instance_ctx(inst); + struct heh_tfm_ctx *ctx = crypto_tfm_ctx(tfm); + struct crypto_shash *cmac; + struct crypto_ablkcipher *ecb; + unsigned int reqsize; + int err; + + cmac = crypto_spawn_shash(&ictx->cmac); + if (IS_ERR(cmac)) + return PTR_ERR(cmac); + + ecb = crypto_spawn_skcipher(&ictx->ecb); + err = PTR_ERR(ecb); + if (IS_ERR(ecb)) + goto err_free_cmac; + + ctx->cmac = cmac; + ctx->ecb = ecb; + + reqsize = crypto_tfm_alg_alignmask(tfm) & + ~(crypto_tfm_ctx_alignment() - 1); + reqsize += max(offsetof(struct heh_req_ctx, u.cmac.desc) + + sizeof(struct shash_desc) + + crypto_shash_descsize(cmac), + offsetof(struct heh_req_ctx, u.ecb.req) + + sizeof(struct ablkcipher_request) + + crypto_ablkcipher_reqsize(ecb)); + tfm->crt_ablkcipher.reqsize = reqsize; + return 0; + +err_free_cmac: + crypto_free_shash(cmac); + return err; +} + +static void heh_exit_tfm(struct crypto_tfm *tfm) +{ + struct heh_tfm_ctx *ctx = crypto_tfm_ctx(tfm); + + gf128mul_free_4k(ctx->tau_key); + crypto_free_shash(ctx->cmac); + crypto_free_ablkcipher(ctx->ecb); +} + +static void heh_free_instance(struct crypto_instance *inst) +{ + struct heh_instance_ctx *ctx = crypto_instance_ctx(inst); + + crypto_drop_shash(&ctx->cmac); + crypto_drop_skcipher(&ctx->ecb); + kfree(inst); +} + +/* + * Create an instance of HEH as a ablkcipher. + * + * This relies on underlying CMAC and ECB algorithms, usually cmac(aes) and + * ecb(aes). For performance reasons we support asynchronous ECB algorithms. + * However, we do not yet support asynchronous CMAC algorithms because CMAC is + * only used on a small fixed amount of data per request, independent of the + * request length. This would change if AEAD or variable-length nonce support + * were to be exposed. + */ +static int heh_create_common(struct crypto_template *tmpl, struct rtattr **tb, + const char *full_name, const char *cmac_name, + const char *ecb_name) +{ + struct crypto_attr_type *algt; + struct crypto_instance *inst; + struct heh_instance_ctx *ctx; + struct shash_alg *cmac; + struct crypto_alg *ecb; + int err; + + algt = crypto_get_attr_type(tb); + if (IS_ERR(algt)) + return PTR_ERR(algt); + + /* User must be asking for something compatible with ablkcipher */ + if ((algt->type ^ CRYPTO_ALG_TYPE_ABLKCIPHER) & algt->mask) + return -EINVAL; + + /* Allocate the ablkcipher instance */ + inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL); + if (!inst) + return -ENOMEM; + + ctx = crypto_instance_ctx(inst); + + /* Set up the cmac and ecb spawns */ + + ctx->cmac.base.inst = inst; + err = crypto_grab_shash(&ctx->cmac, cmac_name, 0, CRYPTO_ALG_ASYNC); + if (err) + goto err_free_inst; + cmac = crypto_spawn_shash_alg(&ctx->cmac); + err = -EINVAL; + if (cmac->digestsize != HEH_BLOCK_SIZE) + goto err_drop_cmac; + + ctx->ecb.base.inst = inst; + err = crypto_grab_skcipher(&ctx->ecb, ecb_name, 0, + crypto_requires_sync(algt->type, + algt->mask)); + if (err) + goto err_drop_cmac; + ecb = crypto_skcipher_spawn_alg(&ctx->ecb); + + /* HEH only supports block ciphers with 16 byte block size */ + err = -EINVAL; + if (ecb->cra_blocksize != HEH_BLOCK_SIZE) + goto err_drop_ecb; + + /* The underlying "ECB" algorithm must not require an IV */ + err = -EINVAL; + if ((ecb->cra_flags & CRYPTO_ALG_TYPE_MASK) == CRYPTO_ALG_TYPE_BLKCIPHER) { + if (ecb->cra_blkcipher.ivsize != 0) + goto err_drop_ecb; + } else { + if (ecb->cra_ablkcipher.ivsize != 0) + goto err_drop_ecb; + } + + /* Set the instance names */ + err = -ENAMETOOLONG; + if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME, + "heh_base(%s,%s)", cmac->base.cra_driver_name, + ecb->cra_driver_name) >= CRYPTO_MAX_ALG_NAME) + goto err_drop_ecb; + + err = -ENAMETOOLONG; + if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME, + "%s", full_name) >= CRYPTO_MAX_ALG_NAME) + goto err_drop_ecb; + + /* Finish initializing the instance */ + + inst->alg.cra_flags = CRYPTO_ALG_TYPE_ABLKCIPHER | + ((cmac->base.cra_flags | ecb->cra_flags) & + CRYPTO_ALG_ASYNC); + inst->alg.cra_blocksize = HEH_BLOCK_SIZE; + inst->alg.cra_ctxsize = sizeof(struct heh_tfm_ctx); + inst->alg.cra_alignmask = ecb->cra_alignmask | (__alignof__(be128) - 1); + inst->alg.cra_priority = ecb->cra_priority; + inst->alg.cra_type = &crypto_ablkcipher_type; + inst->alg.cra_init = heh_init_tfm; + inst->alg.cra_exit = heh_exit_tfm; + + inst->alg.cra_ablkcipher.setkey = heh_setkey; + inst->alg.cra_ablkcipher.encrypt = heh_encrypt; + inst->alg.cra_ablkcipher.decrypt = heh_decrypt; + if ((ecb->cra_flags & CRYPTO_ALG_TYPE_MASK) == CRYPTO_ALG_TYPE_BLKCIPHER) { + inst->alg.cra_ablkcipher.min_keysize = ecb->cra_blkcipher.min_keysize; + inst->alg.cra_ablkcipher.max_keysize = ecb->cra_blkcipher.max_keysize; + } else { + inst->alg.cra_ablkcipher.min_keysize = ecb->cra_ablkcipher.min_keysize; + inst->alg.cra_ablkcipher.max_keysize = ecb->cra_ablkcipher.max_keysize; + } + inst->alg.cra_ablkcipher.ivsize = HEH_BLOCK_SIZE; + + /* Register the instance */ + err = crypto_register_instance(tmpl, inst); + if (err) + goto err_drop_ecb; + return 0; + +err_drop_ecb: + crypto_drop_skcipher(&ctx->ecb); +err_drop_cmac: + crypto_drop_shash(&ctx->cmac); +err_free_inst: + kfree(inst); + return err; +} + +static int heh_create(struct crypto_template *tmpl, struct rtattr **tb) +{ + const char *cipher_name; + char full_name[CRYPTO_MAX_ALG_NAME]; + char cmac_name[CRYPTO_MAX_ALG_NAME]; + char ecb_name[CRYPTO_MAX_ALG_NAME]; + + /* Get the name of the requested block cipher (e.g. aes) */ + cipher_name = crypto_attr_alg_name(tb[1]); + if (IS_ERR(cipher_name)) + return PTR_ERR(cipher_name); + + if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "heh(%s)", cipher_name) >= + CRYPTO_MAX_ALG_NAME) + return -ENAMETOOLONG; + + if (snprintf(cmac_name, CRYPTO_MAX_ALG_NAME, "cmac(%s)", cipher_name) >= + CRYPTO_MAX_ALG_NAME) + return -ENAMETOOLONG; + + if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)", cipher_name) >= + CRYPTO_MAX_ALG_NAME) + return -ENAMETOOLONG; + + return heh_create_common(tmpl, tb, full_name, cmac_name, ecb_name); +} + +static struct crypto_template heh_tmpl = { + .name = "heh", + .create = heh_create, + .free = heh_free_instance, + .module = THIS_MODULE, +}; + +static int heh_base_create(struct crypto_template *tmpl, struct rtattr **tb) +{ + char full_name[CRYPTO_MAX_ALG_NAME]; + const char *cmac_name; + const char *ecb_name; + + cmac_name = crypto_attr_alg_name(tb[1]); + if (IS_ERR(cmac_name)) + return PTR_ERR(cmac_name); + + ecb_name = crypto_attr_alg_name(tb[2]); + if (IS_ERR(ecb_name)) + return PTR_ERR(ecb_name); + + if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "heh_base(%s,%s)", + cmac_name, ecb_name) >= CRYPTO_MAX_ALG_NAME) + return -ENAMETOOLONG; + + return heh_create_common(tmpl, tb, full_name, cmac_name, ecb_name); +} + +/* + * If HEH is instantiated as "heh_base" instead of "heh", then specific + * implementations of cmac and ecb can be specified instead of just the cipher + */ +static struct crypto_template heh_base_tmpl = { + .name = "heh_base", + .create = heh_base_create, + .free = heh_free_instance, + .module = THIS_MODULE, +}; + +static int __init heh_module_init(void) +{ + int err; + + err = crypto_register_template(&heh_tmpl); + if (err) + return err; + + err = crypto_register_template(&heh_base_tmpl); + if (err) + goto out_undo_heh; + + return 0; + +out_undo_heh: + crypto_unregister_template(&heh_tmpl); + return err; +} + +static void __exit heh_module_exit(void) +{ + crypto_unregister_template(&heh_tmpl); + crypto_unregister_template(&heh_base_tmpl); +} + +module_init(heh_module_init); +module_exit(heh_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Hash-Encrypt-Hash block cipher mode"); +MODULE_ALIAS_CRYPTO("heh"); +MODULE_ALIAS_CRYPTO("heh_base"); |