/* * CTR: Counter mode * * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com> * * 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/algapi.h> #include <crypto/ctr.h> #include <linux/err.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/random.h> #include <linux/scatterlist.h> #include <linux/slab.h> struct crypto_ctr_ctx { struct crypto_cipher *child; }; struct crypto_rfc3686_ctx { struct crypto_blkcipher *child; u8 nonce[CTR_RFC3686_NONCE_SIZE]; }; static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key, unsigned int keylen) { struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent); struct crypto_cipher *child = ctx->child; int err; crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) & CRYPTO_TFM_REQ_MASK); err = crypto_cipher_setkey(child, key, keylen); crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) & CRYPTO_TFM_RES_MASK); return err; } static void crypto_ctr_crypt_final(struct blkcipher_walk *walk, struct crypto_cipher *tfm) { unsigned int bsize = crypto_cipher_blocksize(tfm); unsigned long alignmask = crypto_cipher_alignmask(tfm); u8 *ctrblk = walk->iv; u8 tmp[bsize + alignmask]; u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1); u8 *src = walk->src.virt.addr; u8 *dst = walk->dst.virt.addr; unsigned int nbytes = walk->nbytes; crypto_cipher_encrypt_one(tfm, keystream, ctrblk); crypto_xor(keystream, src, nbytes); memcpy(dst, keystream, nbytes); crypto_inc(ctrblk, bsize); } static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk, struct crypto_cipher *tfm) { void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = crypto_cipher_alg(tfm)->cia_encrypt; unsigned int bsize = crypto_cipher_blocksize(tfm); u8 *ctrblk = walk->iv; u8 *src = walk->src.virt.addr; u8 *dst = walk->dst.virt.addr; unsigned int nbytes = walk->nbytes; do { /* create keystream */ fn(crypto_cipher_tfm(tfm), dst, ctrblk); crypto_xor(dst, src, bsize); /* increment counter in counterblock */ crypto_inc(ctrblk, bsize); src += bsize; dst += bsize; } while ((nbytes -= bsize) >= bsize); return nbytes; } static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk, struct crypto_cipher *tfm) { void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = crypto_cipher_alg(tfm)->cia_encrypt; unsigned int bsize = crypto_cipher_blocksize(tfm); unsigned long alignmask = crypto_cipher_alignmask(tfm); unsigned int nbytes = walk->nbytes; u8 *ctrblk = walk->iv; u8 *src = walk->src.virt.addr; u8 tmp[bsize + alignmask]; u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1); do { /* create keystream */ fn(crypto_cipher_tfm(tfm), keystream, ctrblk); crypto_xor(src, keystream, bsize); /* increment counter in counterblock */ crypto_inc(ctrblk, bsize); src += bsize; } while ((nbytes -= bsize) >= bsize); return nbytes; } static int crypto_ctr_crypt(struct blkcipher_desc *desc, struct scatterlist *dst, struct scatterlist *src, unsigned int nbytes) { struct blkcipher_walk walk; struct crypto_blkcipher *tfm = desc->tfm; struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm); struct crypto_cipher *child = ctx->child; unsigned int bsize = crypto_cipher_blocksize(child); int err; blkcipher_walk_init(&walk, dst, src, nbytes); err = blkcipher_walk_virt_block(desc, &walk, bsize); while (walk.nbytes >= bsize) { if (walk.src.virt.addr == walk.dst.virt.addr) nbytes = crypto_ctr_crypt_inplace(&walk, child); else nbytes = crypto_ctr_crypt_segment(&walk, child); err = blkcipher_walk_done(desc, &walk, nbytes); } if (walk.nbytes) { crypto_ctr_crypt_final(&walk, child); err = blkcipher_walk_done(desc, &walk, 0); } return err; } static int crypto_ctr_init_tfm(struct crypto_tfm *tfm) { struct crypto_instance *inst = (void *)tfm->__crt_alg; struct crypto_spawn *spawn = crypto_instance_ctx(inst); struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm); struct crypto_cipher *cipher; cipher = crypto_spawn_cipher(spawn); if (IS_ERR(cipher)) return PTR_ERR(cipher); ctx->child = cipher; return 0; } static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm) { struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm); crypto_free_cipher(ctx->child); } static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb) { struct crypto_instance *inst; struct crypto_alg *alg; int err; err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER); if (err) return ERR_PTR(err); alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER, CRYPTO_ALG_TYPE_MASK); if (IS_ERR(alg)) return ERR_PTR(PTR_ERR(alg)); /* Block size must be >= 4 bytes. */ err = -EINVAL; if (alg->cra_blocksize < 4) goto out_put_alg; /* If this is false we'd fail the alignment of crypto_inc. */ if (alg->cra_blocksize % 4) goto out_put_alg; inst = crypto_alloc_instance("ctr", alg); if (IS_ERR(inst)) goto out; inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER; inst->alg.cra_priority = alg->cra_priority; inst->alg.cra_blocksize = 1; inst->alg.cra_alignmask = alg->cra_alignmask | (__alignof__(u32) - 1); inst->alg.cra_type = &crypto_blkcipher_type; inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize; inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize; inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize; inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx); inst->alg.cra_init = crypto_ctr_init_tfm; inst->alg.cra_exit = crypto_ctr_exit_tfm; inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey; inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt; inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt; inst->alg.cra_blkcipher.geniv = "chainiv"; out: crypto_mod_put(alg); return inst; out_put_alg: inst = ERR_PTR(err); goto out; } static void crypto_ctr_free(struct crypto_instance *inst) { crypto_drop_spawn(crypto_instance_ctx(inst)); kfree(inst); } static struct crypto_template crypto_ctr_tmpl = { .name = "ctr", .alloc = crypto_ctr_alloc, .free = crypto_ctr_free, .module = THIS_MODULE, }; static int crypto_rfc3686_setkey(struct crypto_tfm *parent, const u8 *key, unsigned int keylen) { struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(parent); struct crypto_blkcipher *child = ctx->child; int err; /* the nonce is stored in bytes at end of key */ if (keylen < CTR_RFC3686_NONCE_SIZE) return -EINVAL; memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE), CTR_RFC3686_NONCE_SIZE); keylen -= CTR_RFC3686_NONCE_SIZE; crypto_blkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); crypto_blkcipher_set_flags(child, crypto_tfm_get_flags(parent) & CRYPTO_TFM_REQ_MASK); err = crypto_blkcipher_setkey(child, key, keylen); crypto_tfm_set_flags(parent, crypto_blkcipher_get_flags(child) & CRYPTO_TFM_RES_MASK); return err; } static int crypto_rfc3686_crypt(struct blkcipher_desc *desc, struct scatterlist *dst, struct scatterlist *src, unsigned int nbytes) { struct crypto_blkcipher *tfm = desc->tfm; struct crypto_rfc3686_ctx *ctx = crypto_blkcipher_ctx(tfm); struct crypto_blkcipher *child = ctx->child; unsigned long alignmask = crypto_blkcipher_alignmask(tfm); u8 ivblk[CTR_RFC3686_BLOCK_SIZE + alignmask]; u8 *iv = PTR_ALIGN(ivblk + 0, alignmask + 1); u8 *info = desc->info; int err; /* set up counter block */ memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE); memcpy(iv + CTR_RFC3686_NONCE_SIZE, info, CTR_RFC3686_IV_SIZE); /* initialize counter portion of counter block */ *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) = cpu_to_be32(1); desc->tfm = child; desc->info = iv; err = crypto_blkcipher_encrypt_iv(desc, dst, src, nbytes); desc->tfm = tfm; desc->info = info; return err; } static int crypto_rfc3686_init_tfm(struct crypto_tfm *tfm) { struct crypto_instance *inst = (void *)tfm->__crt_alg; struct crypto_spawn *spawn = crypto_instance_ctx(inst); struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm); struct crypto_blkcipher *cipher; cipher = crypto_spawn_blkcipher(spawn); if (IS_ERR(cipher)) return PTR_ERR(cipher); ctx->child = cipher; return 0; } static void crypto_rfc3686_exit_tfm(struct crypto_tfm *tfm) { struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm); crypto_free_blkcipher(ctx->child); } static struct crypto_instance *crypto_rfc3686_alloc(struct rtattr **tb) { struct crypto_instance *inst; struct crypto_alg *alg; int err; err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER); if (err) return ERR_PTR(err); alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_BLKCIPHER, CRYPTO_ALG_TYPE_MASK); err = PTR_ERR(alg); if (IS_ERR(alg)) return ERR_PTR(err); /* We only support 16-byte blocks. */ err = -EINVAL; if (alg->cra_blkcipher.ivsize != CTR_RFC3686_BLOCK_SIZE) goto out_put_alg; /* Not a stream cipher? */ if (alg->cra_blocksize != 1) goto out_put_alg; inst = crypto_alloc_instance("rfc3686", alg); if (IS_ERR(inst)) goto out; inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER; inst->alg.cra_priority = alg->cra_priority; inst->alg.cra_blocksize = 1; inst->alg.cra_alignmask = alg->cra_alignmask; inst->alg.cra_type = &crypto_blkcipher_type; inst->alg.cra_blkcipher.ivsize = CTR_RFC3686_IV_SIZE; inst->alg.cra_blkcipher.min_keysize = alg->cra_blkcipher.min_keysize + CTR_RFC3686_NONCE_SIZE; inst->alg.cra_blkcipher.max_keysize = alg->cra_blkcipher.max_keysize + CTR_RFC3686_NONCE_SIZE; inst->alg.cra_blkcipher.geniv = "seqiv"; inst->alg.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx); inst->alg.cra_init = crypto_rfc3686_init_tfm; inst->alg.cra_exit = crypto_rfc3686_exit_tfm; inst->alg.cra_blkcipher.setkey = crypto_rfc3686_setkey; inst->alg.cra_blkcipher.encrypt = crypto_rfc3686_crypt; inst->alg.cra_blkcipher.decrypt = crypto_rfc3686_crypt; out: crypto_mod_put(alg); return inst; out_put_alg: inst = ERR_PTR(err); goto out; } static struct crypto_template crypto_rfc3686_tmpl = { .name = "rfc3686", .alloc = crypto_rfc3686_alloc, .free = crypto_ctr_free, .module = THIS_MODULE, }; static int __init crypto_ctr_module_init(void) { int err; err = crypto_register_template(&crypto_ctr_tmpl); if (err) goto out; err = crypto_register_template(&crypto_rfc3686_tmpl); if (err) goto out_drop_ctr; out: return err; out_drop_ctr: crypto_unregister_template(&crypto_ctr_tmpl); goto out; } static void __exit crypto_ctr_module_exit(void) { crypto_unregister_template(&crypto_rfc3686_tmpl); crypto_unregister_template(&crypto_ctr_tmpl); } module_init(crypto_ctr_module_init); module_exit(crypto_ctr_module_exit); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("CTR Counter block mode"); MODULE_ALIAS("rfc3686");