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 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 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 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 } 110 111 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 } 137 138 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 } 172 173 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 } 186 187 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 }; 198 199 static int __init seqiv_module_init(void) 200 { 201 return crypto_register_template(&seqiv_tmpl); 202 } 203 204 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