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32 results

resource.c

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  • echainiv.c 4.47 KiB
    /*
     * echainiv: Encrypted Chain IV Generator
     *
     * This generator generates an IV based on a sequence number by multiplying
     * it with a salt and then encrypting it with the same key as used to encrypt
     * the plain text.  This algorithm requires that the block size be equal
     * to the IV size.  It is mainly useful for CBC.
     *
     * This generator can only be used by algorithms where authentication
     * is performed after encryption (i.e., authenc).
     *
     * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
     *
     * 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/geniv.h>
    #include <crypto/scatterwalk.h>
    #include <crypto/skcipher.h>
    #include <linux/err.h>
    #include <linux/init.h>
    #include <linux/kernel.h>
    #include <linux/module.h>
    #include <linux/slab.h>
    #include <linux/string.h>
    
    static int echainiv_encrypt(struct aead_request *req)
    {
    	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
    	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
    	struct aead_request *subreq = aead_request_ctx(req);
    	__be64 nseqno;
    	u64 seqno;
    	u8 *info;
    	unsigned int ivsize = crypto_aead_ivsize(geniv);
    	int err;
    
    	if (req->cryptlen < ivsize)
    		return -EINVAL;
    
    	aead_request_set_tfm(subreq, ctx->child);
    
    	info = req->iv;
    
    	if (req->src != req->dst) {
    		SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull);
    
    		skcipher_request_set_tfm(nreq, ctx->sknull);
    		skcipher_request_set_callback(nreq, req->base.flags,
    					      NULL, NULL);
    		skcipher_request_set_crypt(nreq, req->src, req->dst,
    					   req->assoclen + req->cryptlen,
    					   NULL);
    
    		err = crypto_skcipher_encrypt(nreq);
    		if (err)
    			return err;
    	}
    
    	aead_request_set_callback(subreq, req->base.flags,
    				  req->base.complete, req->base.data);
    	aead_request_set_crypt(subreq, req->dst, req->dst,
    			       req->cryptlen, info);
    	aead_request_set_ad(subreq, req->assoclen);
    
    	memcpy(&nseqno, info + ivsize - 8, 8);
    	seqno = be64_to_cpu(nseqno);
    	memset(info, 0, ivsize);
    
    	scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
    
    	do {
    		u64 a;
    
    		memcpy(&a, ctx->salt + ivsize - 8, 8);
    
    		a |= 1;
    		a *= seqno;
    
    		memcpy(info + ivsize - 8, &a, 8);
    	} while ((ivsize -= 8));
    
    	return crypto_aead_encrypt(subreq);
    }
    
    static int echainiv_decrypt(struct aead_request *req)
    {
    	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
    	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
    	struct aead_request *subreq = aead_request_ctx(req);
    	crypto_completion_t compl;
    	void *data;
    	unsigned int ivsize = crypto_aead_ivsize(geniv);
    
    	if (req->cryptlen < ivsize)
    		return -EINVAL;
    
    	aead_request_set_tfm(subreq, ctx->child);
    
    	compl = req->base.complete;
    	data = req->base.data;
    
    	aead_request_set_callback(subreq, req->base.flags, compl, data);
    	aead_request_set_crypt(subreq, req->src, req->dst,
    			       req->cryptlen - ivsize, req->iv);
    	aead_request_set_ad(subreq, req->assoclen + ivsize);
    
    	scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
    
    	return crypto_aead_decrypt(subreq);
    }
    
    static int echainiv_aead_create(struct crypto_template *tmpl,
    				struct rtattr **tb)
    {
    	struct aead_instance *inst;
    	int err;
    
    	inst = aead_geniv_alloc(tmpl, tb, 0, 0);
    
    	if (IS_ERR(inst))
    		return PTR_ERR(inst);
    
    	err = -EINVAL;
    	if (inst->alg.ivsize & (sizeof(u64) - 1) || !inst->alg.ivsize)
    		goto free_inst;
    
    	inst->alg.encrypt = echainiv_encrypt;
    	inst->alg.decrypt = echainiv_decrypt;
    
    	inst->alg.init = aead_init_geniv;
    	inst->alg.exit = aead_exit_geniv;
    
    	inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
    	inst->alg.base.cra_ctxsize += inst->alg.ivsize;
    
    	inst->free = aead_geniv_free;
    
    	err = aead_register_instance(tmpl, inst);
    	if (err)
    		goto free_inst;
    
    out:
    	return err;
    
    free_inst:
    	aead_geniv_free(inst);
    	goto out;
    }
    
    static void echainiv_free(struct crypto_instance *inst)
    {
    	aead_geniv_free(aead_instance(inst));
    }
    
    static struct crypto_template echainiv_tmpl = {
    	.name = "echainiv",
    	.create = echainiv_aead_create,
    	.free = echainiv_free,
    	.module = THIS_MODULE,
    };
    
    static int __init echainiv_module_init(void)
    {
    	return crypto_register_template(&echainiv_tmpl);
    }
    
    static void __exit echainiv_module_exit(void)
    {
    	crypto_unregister_template(&echainiv_tmpl);
    }
    
    module_init(echainiv_module_init);
    module_exit(echainiv_module_exit);
    
    MODULE_LICENSE("GPL");
    MODULE_DESCRIPTION("Encrypted Chain IV Generator");
    MODULE_ALIAS_CRYPTO("echainiv");