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(to: req->iv, from: subreq->iv, len: crypto_aead_ivsize(tfm: geniv));
34
35out:
36 kfree_sensitive(objp: 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(tfm: 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(req: subreq, tfm: 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 memcpy_sglist(dst: req->dst, src: req->src,
69 nbytes: req->assoclen + req->cryptlen);
70
71 if (unlikely(!IS_ALIGNED((unsigned long)info,
72 crypto_aead_alignmask(geniv) + 1))) {
73 info = kmemdup(req->iv, ivsize, req->base.flags &
74 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
75 GFP_ATOMIC);
76 if (!info)
77 return -ENOMEM;
78
79 compl = seqiv_aead_encrypt_complete;
80 data = req;
81 }
82
83 aead_request_set_callback(req: subreq, flags: req->base.flags, compl, data);
84 aead_request_set_crypt(req: subreq, src: req->dst, dst: req->dst,
85 cryptlen: req->cryptlen - ivsize, iv: info);
86 aead_request_set_ad(req: subreq, assoclen: req->assoclen + ivsize);
87
88 crypto_xor(dst: info, src: ctx->salt, size: ivsize);
89 scatterwalk_map_and_copy(buf: info, sg: req->dst, start: req->assoclen, nbytes: ivsize, out: 1);
90
91 err = crypto_aead_encrypt(req: subreq);
92 if (unlikely(info != req->iv))
93 seqiv_aead_encrypt_complete2(req, err);
94 return err;
95}
96
97static int seqiv_aead_decrypt(struct aead_request *req)
98{
99 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
100 struct aead_geniv_ctx *ctx = crypto_aead_ctx(tfm: geniv);
101 struct aead_request *subreq = aead_request_ctx(req);
102 crypto_completion_t compl;
103 void *data;
104 unsigned int ivsize = 8;
105
106 if (req->cryptlen < ivsize + crypto_aead_authsize(tfm: geniv))
107 return -EINVAL;
108
109 aead_request_set_tfm(req: subreq, tfm: ctx->child);
110
111 compl = req->base.complete;
112 data = req->base.data;
113
114 aead_request_set_callback(req: subreq, flags: req->base.flags, compl, data);
115 aead_request_set_crypt(req: subreq, src: req->src, dst: req->dst,
116 cryptlen: req->cryptlen - ivsize, iv: req->iv);
117 aead_request_set_ad(req: subreq, assoclen: req->assoclen + ivsize);
118
119 scatterwalk_map_and_copy(buf: req->iv, sg: req->src, start: req->assoclen, nbytes: ivsize, out: 0);
120
121 return crypto_aead_decrypt(req: subreq);
122}
123
124static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb)
125{
126 struct aead_instance *inst;
127 int err;
128
129 inst = aead_geniv_alloc(tmpl, tb);
130
131 if (IS_ERR(ptr: inst))
132 return PTR_ERR(ptr: inst);
133
134 err = -EINVAL;
135 if (inst->alg.ivsize != sizeof(u64))
136 goto free_inst;
137
138 inst->alg.encrypt = seqiv_aead_encrypt;
139 inst->alg.decrypt = seqiv_aead_decrypt;
140
141 inst->alg.init = aead_init_geniv;
142 inst->alg.exit = aead_exit_geniv;
143
144 inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
145 inst->alg.base.cra_ctxsize += inst->alg.ivsize;
146
147 err = aead_register_instance(tmpl, inst);
148 if (err) {
149free_inst:
150 inst->free(inst);
151 }
152 return err;
153}
154
155static struct crypto_template seqiv_tmpl = {
156 .name = "seqiv",
157 .create = seqiv_aead_create,
158 .module = THIS_MODULE,
159};
160
161static int __init seqiv_module_init(void)
162{
163 return crypto_register_template(tmpl: &seqiv_tmpl);
164}
165
166static void __exit seqiv_module_exit(void)
167{
168 crypto_unregister_template(tmpl: &seqiv_tmpl);
169}
170
171module_init(seqiv_module_init);
172module_exit(seqiv_module_exit);
173
174MODULE_LICENSE("GPL");
175MODULE_DESCRIPTION("Sequence Number IV Generator");
176MODULE_ALIAS_CRYPTO("seqiv");
177