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 || 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 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 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 } 107 108 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 } 134 135 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 }; 171 172 static int __init seqiv_module_init(void) 173 { 174 return crypto_register_template(&seqiv_tmpl); 175 } 176 177 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