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	void *data;
54	u8 *info;
55	unsigned int ivsize = 8;
56	int err;
57
58	if (req->cryptlen < ivsize)
59		return -EINVAL;
60
61	aead_request_set_tfm(subreq, ctx->child);
62
63	compl = req->base.complete;
64	data = req->base.data;
65	info = req->iv;
66
67	if (req->src != req->dst) {
68		SYNC_SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull);
69
70		skcipher_request_set_sync_tfm(nreq, ctx->sknull);
71		skcipher_request_set_callback(nreq, req->base.flags,
72					      NULL, NULL);
73		skcipher_request_set_crypt(nreq, req->src, req->dst,
74					   req->assoclen + req->cryptlen,
75					   NULL);
76
77		err = crypto_skcipher_encrypt(nreq);
78		if (err)
79			return err;
80	}
81
82	if (unlikely(!IS_ALIGNED((unsigned long)info,
83				 crypto_aead_alignmask(geniv) + 1))) {
84		info = kmemdup(req->iv, ivsize, req->base.flags &
85			       CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
86			       GFP_ATOMIC);
87		if (!info)
88			return -ENOMEM;
89
90		compl = seqiv_aead_encrypt_complete;
91		data = req;
92	}
93
94	aead_request_set_callback(subreq, req->base.flags, compl, data);
95	aead_request_set_crypt(subreq, req->dst, req->dst,
96			       req->cryptlen - ivsize, info);
97	aead_request_set_ad(subreq, req->assoclen + ivsize);
98
99	crypto_xor(info, ctx->salt, ivsize);
100	scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
101
102	err = crypto_aead_encrypt(subreq);
103	if (unlikely(info != req->iv))
104		seqiv_aead_encrypt_complete2(req, err);
105	return err;
106}
107
108static int seqiv_aead_decrypt(struct aead_request *req)
109{
110	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
111	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
112	struct aead_request *subreq = aead_request_ctx(req);
113	crypto_completion_t compl;
114	void *data;
115	unsigned int ivsize = 8;
116
117	if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
118		return -EINVAL;
119
120	aead_request_set_tfm(subreq, ctx->child);
121
122	compl = req->base.complete;
123	data = req->base.data;
124
125	aead_request_set_callback(subreq, req->base.flags, compl, data);
126	aead_request_set_crypt(subreq, req->src, req->dst,
127			       req->cryptlen - ivsize, req->iv);
128	aead_request_set_ad(subreq, req->assoclen + ivsize);
129
130	scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
131
132	return crypto_aead_decrypt(subreq);
133}
134
135static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb)
136{
137	struct aead_instance *inst;
138	int err;
139
140	inst = aead_geniv_alloc(tmpl, tb);
141
142	if (IS_ERR(inst))
143		return PTR_ERR(inst);
144
145	err = -EINVAL;
146	if (inst->alg.ivsize != sizeof(u64))
147		goto free_inst;
148
149	inst->alg.encrypt = seqiv_aead_encrypt;
150	inst->alg.decrypt = seqiv_aead_decrypt;
151
152	inst->alg.init = aead_init_geniv;
153	inst->alg.exit = aead_exit_geniv;
154
155	inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
156	inst->alg.base.cra_ctxsize += inst->alg.ivsize;
157
158	err = aead_register_instance(tmpl, inst);
159	if (err) {
160free_inst:
161		inst->free(inst);
162	}
163	return err;
164}
165
166static struct crypto_template seqiv_tmpl = {
167	.name = "seqiv",
168	.create = seqiv_aead_create,
169	.module = THIS_MODULE,
170};
171
172static int __init seqiv_module_init(void)
173{
174	return crypto_register_template(&seqiv_tmpl);
175}
176
177static void __exit seqiv_module_exit(void)
178{
179	crypto_unregister_template(&seqiv_tmpl);
180}
181
182subsys_initcall(seqiv_module_init);
183module_exit(seqiv_module_exit);
184
185MODULE_LICENSE("GPL");
186MODULE_DESCRIPTION("Sequence Number IV Generator");
187MODULE_ALIAS_CRYPTO("seqiv");
188