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
seqiv_aead_encrypt_complete2(struct aead_request * req,int err)21 static 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
35 out:
36 kfree_sensitive(subreq->iv);
37 }
38
seqiv_aead_encrypt_complete(void * data,int err)39 static 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
seqiv_aead_encrypt(struct aead_request * req)47 static 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 memcpy_sglist(req->dst, req->src,
69 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(subreq, req->base.flags, compl, data);
84 aead_request_set_crypt(subreq, req->dst, req->dst,
85 req->cryptlen - ivsize, info);
86 aead_request_set_ad(subreq, req->assoclen + ivsize);
87
88 crypto_xor(info, ctx->salt, ivsize);
89 scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
90
91 err = crypto_aead_encrypt(subreq);
92 if (unlikely(info != req->iv))
93 seqiv_aead_encrypt_complete2(req, err);
94 return err;
95 }
96
seqiv_aead_decrypt(struct aead_request * req)97 static 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(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(geniv))
107 return -EINVAL;
108
109 aead_request_set_tfm(subreq, ctx->child);
110
111 compl = req->base.complete;
112 data = req->base.data;
113
114 aead_request_set_callback(subreq, req->base.flags, compl, data);
115 aead_request_set_crypt(subreq, req->src, req->dst,
116 req->cryptlen - ivsize, req->iv);
117 aead_request_set_ad(subreq, req->assoclen + ivsize);
118
119 scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
120
121 return crypto_aead_decrypt(subreq);
122 }
123
seqiv_aead_create(struct crypto_template * tmpl,struct rtattr ** tb)124 static 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(inst))
132 return PTR_ERR(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) {
149 free_inst:
150 inst->free(inst);
151 }
152 return err;
153 }
154
155 static struct crypto_template seqiv_tmpl = {
156 .name = "seqiv",
157 .create = seqiv_aead_create,
158 .module = THIS_MODULE,
159 };
160
seqiv_module_init(void)161 static int __init seqiv_module_init(void)
162 {
163 return crypto_register_template(&seqiv_tmpl);
164 }
165
seqiv_module_exit(void)166 static void __exit seqiv_module_exit(void)
167 {
168 crypto_unregister_template(&seqiv_tmpl);
169 }
170
171 module_init(seqiv_module_init);
172 module_exit(seqiv_module_exit);
173
174 MODULE_LICENSE("GPL");
175 MODULE_DESCRIPTION("Sequence Number IV Generator");
176 MODULE_ALIAS_CRYPTO("seqiv");
177