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
21 static void seqiv_free(struct crypto_instance *inst);
22
seqiv_aead_encrypt_complete2(struct aead_request * req,int err)23 static void seqiv_aead_encrypt_complete2(struct aead_request *req, int err)
24 {
25 struct aead_request *subreq = aead_request_ctx(req);
26 struct crypto_aead *geniv;
27
28 if (err == -EINPROGRESS)
29 return;
30
31 if (err)
32 goto out;
33
34 geniv = crypto_aead_reqtfm(req);
35 memcpy(req->iv, subreq->iv, crypto_aead_ivsize(geniv));
36
37 out:
38 kzfree(subreq->iv);
39 }
40
seqiv_aead_encrypt_complete(struct crypto_async_request * base,int err)41 static void seqiv_aead_encrypt_complete(struct crypto_async_request *base,
42 int err)
43 {
44 struct aead_request *req = base->data;
45
46 seqiv_aead_encrypt_complete2(req, err);
47 aead_request_complete(req, err);
48 }
49
seqiv_aead_encrypt(struct aead_request * req)50 static int seqiv_aead_encrypt(struct aead_request *req)
51 {
52 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
53 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
54 struct aead_request *subreq = aead_request_ctx(req);
55 crypto_completion_t compl;
56 void *data;
57 u8 *info;
58 unsigned int ivsize = 8;
59 int err;
60
61 if (req->cryptlen < ivsize)
62 return -EINVAL;
63
64 aead_request_set_tfm(subreq, ctx->child);
65
66 compl = req->base.complete;
67 data = req->base.data;
68 info = req->iv;
69
70 if (req->src != req->dst) {
71 SYNC_SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull);
72
73 skcipher_request_set_sync_tfm(nreq, ctx->sknull);
74 skcipher_request_set_callback(nreq, req->base.flags,
75 NULL, NULL);
76 skcipher_request_set_crypt(nreq, req->src, req->dst,
77 req->assoclen + req->cryptlen,
78 NULL);
79
80 err = crypto_skcipher_encrypt(nreq);
81 if (err)
82 return err;
83 }
84
85 if (unlikely(!IS_ALIGNED((unsigned long)info,
86 crypto_aead_alignmask(geniv) + 1))) {
87 info = kmemdup(req->iv, ivsize, req->base.flags &
88 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
89 GFP_ATOMIC);
90 if (!info)
91 return -ENOMEM;
92
93 compl = seqiv_aead_encrypt_complete;
94 data = req;
95 }
96
97 aead_request_set_callback(subreq, req->base.flags, compl, data);
98 aead_request_set_crypt(subreq, req->dst, req->dst,
99 req->cryptlen - ivsize, info);
100 aead_request_set_ad(subreq, req->assoclen + ivsize);
101
102 crypto_xor(info, ctx->salt, ivsize);
103 scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
104
105 err = crypto_aead_encrypt(subreq);
106 if (unlikely(info != req->iv))
107 seqiv_aead_encrypt_complete2(req, err);
108 return err;
109 }
110
seqiv_aead_decrypt(struct aead_request * req)111 static int seqiv_aead_decrypt(struct aead_request *req)
112 {
113 struct crypto_aead *geniv = crypto_aead_reqtfm(req);
114 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
115 struct aead_request *subreq = aead_request_ctx(req);
116 crypto_completion_t compl;
117 void *data;
118 unsigned int ivsize = 8;
119
120 if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
121 return -EINVAL;
122
123 aead_request_set_tfm(subreq, ctx->child);
124
125 compl = req->base.complete;
126 data = req->base.data;
127
128 aead_request_set_callback(subreq, req->base.flags, compl, data);
129 aead_request_set_crypt(subreq, req->src, req->dst,
130 req->cryptlen - ivsize, req->iv);
131 aead_request_set_ad(subreq, req->assoclen + ivsize);
132
133 scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
134
135 return crypto_aead_decrypt(subreq);
136 }
137
seqiv_aead_create(struct crypto_template * tmpl,struct rtattr ** tb)138 static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb)
139 {
140 struct aead_instance *inst;
141 int err;
142
143 inst = aead_geniv_alloc(tmpl, tb, 0, 0);
144
145 if (IS_ERR(inst))
146 return PTR_ERR(inst);
147
148 err = -EINVAL;
149 if (inst->alg.ivsize != sizeof(u64))
150 goto free_inst;
151
152 inst->alg.encrypt = seqiv_aead_encrypt;
153 inst->alg.decrypt = seqiv_aead_decrypt;
154
155 inst->alg.init = aead_init_geniv;
156 inst->alg.exit = aead_exit_geniv;
157
158 inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
159 inst->alg.base.cra_ctxsize += inst->alg.ivsize;
160
161 err = aead_register_instance(tmpl, inst);
162 if (err)
163 goto free_inst;
164
165 out:
166 return err;
167
168 free_inst:
169 aead_geniv_free(inst);
170 goto out;
171 }
172
seqiv_create(struct crypto_template * tmpl,struct rtattr ** tb)173 static int seqiv_create(struct crypto_template *tmpl, struct rtattr **tb)
174 {
175 struct crypto_attr_type *algt;
176
177 algt = crypto_get_attr_type(tb);
178 if (IS_ERR(algt))
179 return PTR_ERR(algt);
180
181 if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK)
182 return -EINVAL;
183
184 return seqiv_aead_create(tmpl, tb);
185 }
186
seqiv_free(struct crypto_instance * inst)187 static void seqiv_free(struct crypto_instance *inst)
188 {
189 aead_geniv_free(aead_instance(inst));
190 }
191
192 static struct crypto_template seqiv_tmpl = {
193 .name = "seqiv",
194 .create = seqiv_create,
195 .free = seqiv_free,
196 .module = THIS_MODULE,
197 };
198
seqiv_module_init(void)199 static int __init seqiv_module_init(void)
200 {
201 return crypto_register_template(&seqiv_tmpl);
202 }
203
seqiv_module_exit(void)204 static void __exit seqiv_module_exit(void)
205 {
206 crypto_unregister_template(&seqiv_tmpl);
207 }
208
209 subsys_initcall(seqiv_module_init);
210 module_exit(seqiv_module_exit);
211
212 MODULE_LICENSE("GPL");
213 MODULE_DESCRIPTION("Sequence Number IV Generator");
214 MODULE_ALIAS_CRYPTO("seqiv");
215
