/* * Cryptographic API. * * HMAC: Keyed-Hashing for Message Authentication (RFC2104). * * Copyright (c) 2002 James Morris <jmorris@intercode.com.au> * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> * * The HMAC implementation is derived from USAGI. * Copyright (c) 2002 Kazunori Miyazawa <miyazawa@linux-ipv6.org> / USAGI * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the Free * Software Foundation; either version 2 of the License, or (at your option) * any later version. * */ #include <crypto/internal/hash.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 <linux/string.h> struct hmac_ctx { struct crypto_hash *child; }; static inline void *align_ptr(void *p, unsigned int align) { return (void *)ALIGN((unsigned long)p, align); } static inline struct hmac_ctx *hmac_ctx(struct crypto_hash *tfm) { return align_ptr(crypto_hash_ctx_aligned(tfm) + crypto_hash_blocksize(tfm) * 2 + crypto_hash_digestsize(tfm), sizeof(void *)); } static int hmac_setkey(struct crypto_hash *parent, const u8 *inkey, unsigned int keylen) { int bs = crypto_hash_blocksize(parent); int ds = crypto_hash_digestsize(parent); char *ipad = crypto_hash_ctx_aligned(parent); char *opad = ipad + bs; char *digest = opad + bs; struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); struct crypto_hash *tfm = ctx->child; unsigned int i; if (keylen > bs) { struct hash_desc desc; struct scatterlist tmp; int tmplen; int err; desc.tfm = tfm; desc.flags = crypto_hash_get_flags(parent); desc.flags &= CRYPTO_TFM_REQ_MAY_SLEEP; err = crypto_hash_init(&desc); if (err) return err; tmplen = bs * 2 + ds; sg_init_one(&tmp, ipad, tmplen); for (; keylen > tmplen; inkey += tmplen, keylen -= tmplen) { memcpy(ipad, inkey, tmplen); err = crypto_hash_update(&desc, &tmp, tmplen); if (err) return err; } if (keylen) { memcpy(ipad, inkey, keylen); err = crypto_hash_update(&desc, &tmp, keylen); if (err) return err; } err = crypto_hash_final(&desc, digest); if (err) return err; inkey = digest; keylen = ds; } memcpy(ipad, inkey, keylen); memset(ipad + keylen, 0, bs - keylen); memcpy(opad, ipad, bs); for (i = 0; i < bs; i++) { ipad[i] ^= 0x36; opad[i] ^= 0x5c; } return 0; } static int hmac_init(struct hash_desc *pdesc) { struct crypto_hash *parent = pdesc->tfm; int bs = crypto_hash_blocksize(parent); int ds = crypto_hash_digestsize(parent); char *ipad = crypto_hash_ctx_aligned(parent); struct hmac_ctx *ctx = align_ptr(ipad + bs * 2 + ds, sizeof(void *)); struct hash_desc desc; struct scatterlist tmp; int err; desc.tfm = ctx->child; desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; sg_init_one(&tmp, ipad, bs); err = crypto_hash_init(&desc); if (unlikely(err)) return err; return crypto_hash_update(&desc, &tmp, bs); } static int hmac_update(struct hash_desc *pdesc, struct scatterlist *sg, unsigned int nbytes) { struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm); struct hash_desc desc; desc.tfm = ctx->child; desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; return crypto_hash_update(&desc, sg, nbytes); } static int hmac_final(struct hash_desc *pdesc, u8 *out) { struct crypto_hash *parent = pdesc->tfm; int bs = crypto_hash_blocksize(parent); int ds = crypto_hash_digestsize(parent); char *opad = crypto_hash_ctx_aligned(parent) + bs; char *digest = opad + bs; struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); struct hash_desc desc; struct scatterlist tmp; int err; desc.tfm = ctx->child; desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; sg_init_one(&tmp, opad, bs + ds); err = crypto_hash_final(&desc, digest); if (unlikely(err)) return err; return crypto_hash_digest(&desc, &tmp, bs + ds, out); } static int hmac_digest(struct hash_desc *pdesc, struct scatterlist *sg, unsigned int nbytes, u8 *out) { struct crypto_hash *parent = pdesc->tfm; int bs = crypto_hash_blocksize(parent); int ds = crypto_hash_digestsize(parent); char *ipad = crypto_hash_ctx_aligned(parent); char *opad = ipad + bs; char *digest = opad + bs; struct hmac_ctx *ctx = align_ptr(digest + ds, sizeof(void *)); struct hash_desc desc; struct scatterlist sg1[2]; struct scatterlist sg2[1]; int err; desc.tfm = ctx->child; desc.flags = pdesc->flags & CRYPTO_TFM_REQ_MAY_SLEEP; sg_init_table(sg1, 2); sg_set_buf(sg1, ipad, bs); scatterwalk_sg_chain(sg1, 2, sg); sg_init_table(sg2, 1); sg_set_buf(sg2, opad, bs + ds); err = crypto_hash_digest(&desc, sg1, nbytes + bs, digest); if (unlikely(err)) return err; return crypto_hash_digest(&desc, sg2, bs + ds, out); } static int hmac_init_tfm(struct crypto_tfm *tfm) { struct crypto_hash *hash; struct crypto_instance *inst = (void *)tfm->__crt_alg; struct crypto_spawn *spawn = crypto_instance_ctx(inst); struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); hash = crypto_spawn_hash(spawn); if (IS_ERR(hash)) return PTR_ERR(hash); ctx->child = hash; return 0; } static void hmac_exit_tfm(struct crypto_tfm *tfm) { struct hmac_ctx *ctx = hmac_ctx(__crypto_hash_cast(tfm)); crypto_free_hash(ctx->child); } static void hmac_free(struct crypto_instance *inst) { crypto_drop_spawn(crypto_instance_ctx(inst)); kfree(inst); } static struct crypto_instance *hmac_alloc(struct rtattr **tb) { struct crypto_instance *inst; struct crypto_alg *alg; int err; int ds; err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_HASH); if (err) return ERR_PTR(err); alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_HASH, CRYPTO_ALG_TYPE_HASH_MASK); if (IS_ERR(alg)) return ERR_CAST(alg); inst = ERR_PTR(-EINVAL); ds = alg->cra_type == &crypto_hash_type ? alg->cra_hash.digestsize : alg->cra_type ? __crypto_shash_alg(alg)->digestsize : alg->cra_digest.dia_digestsize; if (ds > alg->cra_blocksize) goto out_put_alg; inst = crypto_alloc_instance("hmac", alg); if (IS_ERR(inst)) goto out_put_alg; inst->alg.cra_flags = CRYPTO_ALG_TYPE_HASH; inst->alg.cra_priority = alg->cra_priority; inst->alg.cra_blocksize = alg->cra_blocksize; inst->alg.cra_alignmask = alg->cra_alignmask; inst->alg.cra_type = &crypto_hash_type; inst->alg.cra_hash.digestsize = ds; inst->alg.cra_ctxsize = sizeof(struct hmac_ctx) + ALIGN(inst->alg.cra_blocksize * 2 + ds, sizeof(void *)); inst->alg.cra_init = hmac_init_tfm; inst->alg.cra_exit = hmac_exit_tfm; inst->alg.cra_hash.init = hmac_init; inst->alg.cra_hash.update = hmac_update; inst->alg.cra_hash.final = hmac_final; inst->alg.cra_hash.digest = hmac_digest; inst->alg.cra_hash.setkey = hmac_setkey; out_put_alg: crypto_mod_put(alg); return inst; } static struct crypto_template hmac_tmpl = { .name = "hmac", .alloc = hmac_alloc, .free = hmac_free, .module = THIS_MODULE, }; static int __init hmac_module_init(void) { return crypto_register_template(&hmac_tmpl); } static void __exit hmac_module_exit(void) { crypto_unregister_template(&hmac_tmpl); } module_init(hmac_module_init); module_exit(hmac_module_exit); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("HMAC hash algorithm");