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