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 memcpy_sglist(req->dst, req->src, 69 req->assoclen + req->cryptlen); 70 71 if (unlikely(!IS_ALIGNED((unsigned long)info, 72 crypto_aead_alignmask(geniv) + 1))) { 73 info = kmemdup(req->iv, ivsize, req->base.flags & 74 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL : 75 GFP_ATOMIC); 76 if (!info) 77 return -ENOMEM; 78 79 compl = seqiv_aead_encrypt_complete; 80 data = req; 81 } 82 83 aead_request_set_callback(subreq, req->base.flags, compl, data); 84 aead_request_set_crypt(subreq, req->dst, req->dst, 85 req->cryptlen - ivsize, info); 86 aead_request_set_ad(subreq, req->assoclen + ivsize); 87 88 crypto_xor(info, ctx->salt, ivsize); 89 scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1); 90 91 err = crypto_aead_encrypt(subreq); 92 if (unlikely(info != req->iv)) 93 seqiv_aead_encrypt_complete2(req, err); 94 return err; 95 } 96 97 static int seqiv_aead_decrypt(struct aead_request *req) 98 { 99 struct crypto_aead *geniv = crypto_aead_reqtfm(req); 100 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv); 101 struct aead_request *subreq = aead_request_ctx(req); 102 crypto_completion_t compl; 103 void *data; 104 unsigned int ivsize = 8; 105 106 if (req->cryptlen < ivsize + crypto_aead_authsize(geniv)) 107 return -EINVAL; 108 109 aead_request_set_tfm(subreq, ctx->child); 110 111 compl = req->base.complete; 112 data = req->base.data; 113 114 aead_request_set_callback(subreq, req->base.flags, compl, data); 115 aead_request_set_crypt(subreq, req->src, req->dst, 116 req->cryptlen - ivsize, req->iv); 117 aead_request_set_ad(subreq, req->assoclen + ivsize); 118 119 scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0); 120 121 return crypto_aead_decrypt(subreq); 122 } 123 124 static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb) 125 { 126 struct aead_instance *inst; 127 int err; 128 129 inst = aead_geniv_alloc(tmpl, tb); 130 131 if (IS_ERR(inst)) 132 return PTR_ERR(inst); 133 134 err = -EINVAL; 135 if (inst->alg.ivsize != sizeof(u64)) 136 goto free_inst; 137 138 inst->alg.encrypt = seqiv_aead_encrypt; 139 inst->alg.decrypt = seqiv_aead_decrypt; 140 141 inst->alg.init = aead_init_geniv; 142 inst->alg.exit = aead_exit_geniv; 143 144 inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx); 145 inst->alg.base.cra_ctxsize += inst->alg.ivsize; 146 147 err = aead_register_instance(tmpl, inst); 148 if (err) { 149 free_inst: 150 inst->free(inst); 151 } 152 return err; 153 } 154 155 static struct crypto_template seqiv_tmpl = { 156 .name = "seqiv", 157 .create = seqiv_aead_create, 158 .module = THIS_MODULE, 159 }; 160 161 static int __init seqiv_module_init(void) 162 { 163 return crypto_register_template(&seqiv_tmpl); 164 } 165 166 static void __exit seqiv_module_exit(void) 167 { 168 crypto_unregister_template(&seqiv_tmpl); 169 } 170 171 module_init(seqiv_module_init); 172 module_exit(seqiv_module_exit); 173 174 MODULE_LICENSE("GPL"); 175 MODULE_DESCRIPTION("Sequence Number IV Generator"); 176 MODULE_ALIAS_CRYPTO("seqiv"); 177