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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");