seqiv.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * seqiv: Sequence Number IV Generator
  4 *
  5 * This generator generates an IV based on a sequence number by xoring it
  6 * with a salt.  This algorithm is mainly useful for CTR and similar modes.
  7 *
  8 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
  9 */
 10
 11#include <crypto/internal/geniv.h>
 12#include <crypto/scatterwalk.h>
 13#include <crypto/skcipher.h>
 14#include <linux/err.h>
 15#include <linux/init.h>
 16#include <linux/kernel.h>
 17#include <linux/module.h>
 18#include <linux/slab.h>
 19#include <linux/string.h>
 20
 21static void seqiv_aead_encrypt_complete2(struct aead_request *req, int err)
 22{
 23	struct aead_request *subreq = aead_request_ctx(req);
 24	struct crypto_aead *geniv;
 25
 26	if (err == -EINPROGRESS || err == -EBUSY)
 27		return;
 28
 29	if (err)
 30		goto out;
 31
 32	geniv = crypto_aead_reqtfm(req);
 33	memcpy(req->iv, subreq->iv, crypto_aead_ivsize(geniv));
 34
 35out:
 36	kfree_sensitive(subreq->iv);
 37}
 38
 39static void seqiv_aead_encrypt_complete(void *data, int err)
 40{
 41	struct aead_request *req = data;
 42
 43	seqiv_aead_encrypt_complete2(req, err);
 44	aead_request_complete(req, err);
 45}
 46
 47static int seqiv_aead_encrypt(struct aead_request *req)
 48{
 49	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
 50	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
 51	struct aead_request *subreq = aead_request_ctx(req);
 52	crypto_completion_t compl;
 53	bool unaligned_info;
 54	void *data;
 55	u8 *info;
 56	unsigned int ivsize = 8;
 57	int err;
 58
 59	if (req->cryptlen < ivsize)
 60		return -EINVAL;
 61
 62	aead_request_set_tfm(subreq, ctx->child);
 63
 64	compl = req->base.complete;
 65	data = req->base.data;
 66	info = req->iv;
 67
 68	if (req->src != req->dst)
 69		memcpy_sglist(req->dst, req->src,
 70			      req->assoclen + req->cryptlen);
 71
 72	unaligned_info = !IS_ALIGNED((unsigned long)info,
 73				     crypto_aead_alignmask(geniv) + 1);
 74	if (unlikely(unaligned_info)) {
 75		info = kmemdup(req->iv, ivsize, req->base.flags &
 76			       CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
 77			       GFP_ATOMIC);
 78		if (!info)
 79			return -ENOMEM;
 80
 81		compl = seqiv_aead_encrypt_complete;
 82		data = req;
 83	}
 84
 85	aead_request_set_callback(subreq, req->base.flags, compl, data);
 86	aead_request_set_crypt(subreq, req->dst, req->dst,
 87			       req->cryptlen - ivsize, info);
 88	aead_request_set_ad(subreq, req->assoclen + ivsize);
 89
 90	crypto_xor(info, ctx->salt, ivsize);
 91	scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
 92
 93	err = crypto_aead_encrypt(subreq);
 94	if (unlikely(unaligned_info))
 95		seqiv_aead_encrypt_complete2(req, err);
 96	return err;
 97}
 98
 99static int seqiv_aead_decrypt(struct aead_request *req)
100{
101	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
102	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
103	struct aead_request *subreq = aead_request_ctx(req);
104	crypto_completion_t compl;
105	void *data;
106	unsigned int ivsize = 8;
107
108	if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
109		return -EINVAL;
110
111	aead_request_set_tfm(subreq, ctx->child);
112
113	compl = req->base.complete;
114	data = req->base.data;
115
116	aead_request_set_callback(subreq, req->base.flags, compl, data);
117	aead_request_set_crypt(subreq, req->src, req->dst,
118			       req->cryptlen - ivsize, req->iv);
119	aead_request_set_ad(subreq, req->assoclen + ivsize);
120
121	scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
122
123	return crypto_aead_decrypt(subreq);
124}
125
126static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb)
127{
128	struct aead_instance *inst;
129	int err;
130
131	inst = aead_geniv_alloc(tmpl, tb);
132
133	if (IS_ERR(inst))
134		return PTR_ERR(inst);
135
136	err = -EINVAL;
137	if (inst->alg.ivsize != sizeof(u64))
138		goto free_inst;
139
140	inst->alg.encrypt = seqiv_aead_encrypt;
141	inst->alg.decrypt = seqiv_aead_decrypt;
142
143	inst->alg.init = aead_init_geniv;
144	inst->alg.exit = aead_exit_geniv;
145
146	inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
147	inst->alg.base.cra_ctxsize += inst->alg.ivsize;
148
149	err = aead_register_instance(tmpl, inst);
150	if (err) {
151free_inst:
152		inst->free(inst);
153	}
154	return err;
155}
156
157static struct crypto_template seqiv_tmpl = {
158	.name = "seqiv",
159	.create = seqiv_aead_create,
160	.module = THIS_MODULE,
161};
162
163static int __init seqiv_module_init(void)
164{
165	return crypto_register_template(&seqiv_tmpl);
166}
167
168static void __exit seqiv_module_exit(void)
169{
170	crypto_unregister_template(&seqiv_tmpl);
171}
172
173module_init(seqiv_module_init);
174module_exit(seqiv_module_exit);
175
176MODULE_LICENSE("GPL");
177MODULE_DESCRIPTION("Sequence Number IV Generator");
178MODULE_ALIAS_CRYPTO("seqiv");