xref: /linux/crypto/seqiv.c (revision 9a87ffc99ec8eb8d35eed7c4f816d75f5cc9662e)
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 		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 
seqiv_aead_decrypt(struct aead_request * req)108 static 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 
seqiv_aead_create(struct crypto_template * tmpl,struct rtattr ** tb)135 static 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) {
160 free_inst:
161 		inst->free(inst);
162 	}
163 	return err;
164 }
165 
166 static struct crypto_template seqiv_tmpl = {
167 	.name = "seqiv",
168 	.create = seqiv_aead_create,
169 	.module = THIS_MODULE,
170 };
171 
seqiv_module_init(void)172 static int __init seqiv_module_init(void)
173 {
174 	return crypto_register_template(&seqiv_tmpl);
175 }
176 
seqiv_module_exit(void)177 static void __exit seqiv_module_exit(void)
178 {
179 	crypto_unregister_template(&seqiv_tmpl);
180 }
181 
182 subsys_initcall(seqiv_module_init);
183 module_exit(seqiv_module_exit);
184 
185 MODULE_LICENSE("GPL");
186 MODULE_DESCRIPTION("Sequence Number IV Generator");
187 MODULE_ALIAS_CRYPTO("seqiv");
188