1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* Instantiate a public key crypto key from an X.509 Certificate 3 * 4 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #define pr_fmt(fmt) "X.509: "fmt 9 #include <linux/module.h> 10 #include <linux/kernel.h> 11 #include <linux/slab.h> 12 #include <keys/asymmetric-subtype.h> 13 #include <keys/asymmetric-parser.h> 14 #include <keys/system_keyring.h> 15 #include <crypto/hash.h> 16 #include "asymmetric_keys.h" 17 #include "x509_parser.h" 18 19 /* 20 * Set up the signature parameters in an X.509 certificate. This involves 21 * digesting the signed data and extracting the signature. 22 */ 23 int x509_get_sig_params(struct x509_certificate *cert) 24 { 25 struct public_key_signature *sig = cert->sig; 26 struct crypto_shash *tfm; 27 struct shash_desc *desc; 28 size_t desc_size; 29 int ret; 30 31 pr_devel("==>%s()\n", __func__); 32 33 sig->data = cert->tbs; 34 sig->data_size = cert->tbs_size; 35 36 sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL); 37 if (!sig->s) 38 return -ENOMEM; 39 40 sig->s_size = cert->raw_sig_size; 41 42 /* Allocate the hashing algorithm we're going to need and find out how 43 * big the hash operational data will be. 44 */ 45 tfm = crypto_alloc_shash(sig->hash_algo, 0, 0); 46 if (IS_ERR(tfm)) { 47 if (PTR_ERR(tfm) == -ENOENT) { 48 cert->unsupported_sig = true; 49 return 0; 50 } 51 return PTR_ERR(tfm); 52 } 53 54 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); 55 sig->digest_size = crypto_shash_digestsize(tfm); 56 57 ret = -ENOMEM; 58 sig->digest = kmalloc(sig->digest_size, GFP_KERNEL); 59 if (!sig->digest) 60 goto error; 61 62 desc = kzalloc(desc_size, GFP_KERNEL); 63 if (!desc) 64 goto error; 65 66 desc->tfm = tfm; 67 68 ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size, sig->digest); 69 if (ret < 0) 70 goto error_2; 71 72 ret = is_hash_blacklisted(sig->digest, sig->digest_size, 73 BLACKLIST_HASH_X509_TBS); 74 if (ret == -EKEYREJECTED) { 75 pr_err("Cert %*phN is blacklisted\n", 76 sig->digest_size, sig->digest); 77 cert->blacklisted = true; 78 ret = 0; 79 } 80 81 error_2: 82 kfree(desc); 83 error: 84 crypto_free_shash(tfm); 85 pr_devel("<==%s() = %d\n", __func__, ret); 86 return ret; 87 } 88 89 /* 90 * Check for self-signedness in an X.509 cert and if found, check the signature 91 * immediately if we can. 92 */ 93 int x509_check_for_self_signed(struct x509_certificate *cert) 94 { 95 int ret = 0; 96 97 pr_devel("==>%s()\n", __func__); 98 99 if (cert->raw_subject_size != cert->raw_issuer_size || 100 memcmp(cert->raw_subject, cert->raw_issuer, 101 cert->raw_issuer_size) != 0) 102 goto not_self_signed; 103 104 if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) { 105 /* If the AKID is present it may have one or two parts. If 106 * both are supplied, both must match. 107 */ 108 bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]); 109 bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]); 110 111 if (!a && !b) 112 goto not_self_signed; 113 114 ret = -EKEYREJECTED; 115 if (((a && !b) || (b && !a)) && 116 cert->sig->auth_ids[0] && cert->sig->auth_ids[1]) 117 goto out; 118 } 119 120 ret = public_key_verify_signature(cert->pub, cert->sig); 121 if (ret < 0) { 122 if (ret == -ENOPKG) { 123 cert->unsupported_sig = true; 124 ret = 0; 125 } 126 goto out; 127 } 128 129 pr_devel("Cert Self-signature verified"); 130 cert->self_signed = true; 131 132 out: 133 pr_devel("<==%s() = %d\n", __func__, ret); 134 return ret; 135 136 not_self_signed: 137 pr_devel("<==%s() = 0 [not]\n", __func__); 138 return 0; 139 } 140 141 /* 142 * Attempt to parse a data blob for a key as an X509 certificate. 143 */ 144 static int x509_key_preparse(struct key_preparsed_payload *prep) 145 { 146 struct asymmetric_key_ids *kids; 147 struct x509_certificate *cert; 148 const char *q; 149 size_t srlen, sulen; 150 char *desc = NULL, *p; 151 int ret; 152 153 cert = x509_cert_parse(prep->data, prep->datalen); 154 if (IS_ERR(cert)) 155 return PTR_ERR(cert); 156 157 pr_devel("Cert Issuer: %s\n", cert->issuer); 158 pr_devel("Cert Subject: %s\n", cert->subject); 159 pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo); 160 pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to); 161 162 cert->pub->id_type = "X509"; 163 164 if (cert->unsupported_sig) { 165 public_key_signature_free(cert->sig); 166 cert->sig = NULL; 167 } else { 168 pr_devel("Cert Signature: %s + %s\n", 169 cert->sig->pkey_algo, cert->sig->hash_algo); 170 } 171 172 /* Don't permit addition of blacklisted keys */ 173 ret = -EKEYREJECTED; 174 if (cert->blacklisted) 175 goto error_free_cert; 176 177 /* Propose a description */ 178 sulen = strlen(cert->subject); 179 if (cert->raw_skid) { 180 srlen = cert->raw_skid_size; 181 q = cert->raw_skid; 182 } else { 183 srlen = cert->raw_serial_size; 184 q = cert->raw_serial; 185 } 186 187 ret = -ENOMEM; 188 desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL); 189 if (!desc) 190 goto error_free_cert; 191 p = memcpy(desc, cert->subject, sulen); 192 p += sulen; 193 *p++ = ':'; 194 *p++ = ' '; 195 p = bin2hex(p, q, srlen); 196 *p = 0; 197 198 kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL); 199 if (!kids) 200 goto error_free_desc; 201 kids->id[0] = cert->id; 202 kids->id[1] = cert->skid; 203 kids->id[2] = asymmetric_key_generate_id(cert->raw_subject, 204 cert->raw_subject_size, 205 "", 0); 206 if (IS_ERR(kids->id[2])) { 207 ret = PTR_ERR(kids->id[2]); 208 goto error_free_kids; 209 } 210 211 /* We're pinning the module by being linked against it */ 212 __module_get(public_key_subtype.owner); 213 prep->payload.data[asym_subtype] = &public_key_subtype; 214 prep->payload.data[asym_key_ids] = kids; 215 prep->payload.data[asym_crypto] = cert->pub; 216 prep->payload.data[asym_auth] = cert->sig; 217 prep->description = desc; 218 prep->quotalen = 100; 219 220 /* We've finished with the certificate */ 221 cert->pub = NULL; 222 cert->id = NULL; 223 cert->skid = NULL; 224 cert->sig = NULL; 225 desc = NULL; 226 kids = NULL; 227 ret = 0; 228 229 error_free_kids: 230 kfree(kids); 231 error_free_desc: 232 kfree(desc); 233 error_free_cert: 234 x509_free_certificate(cert); 235 return ret; 236 } 237 238 static struct asymmetric_key_parser x509_key_parser = { 239 .owner = THIS_MODULE, 240 .name = "x509", 241 .parse = x509_key_preparse, 242 }; 243 244 /* 245 * Module stuff 246 */ 247 extern int __init certs_selftest(void); 248 static int __init x509_key_init(void) 249 { 250 int ret; 251 252 ret = register_asymmetric_key_parser(&x509_key_parser); 253 if (ret < 0) 254 return ret; 255 return fips_signature_selftest(); 256 } 257 258 static void __exit x509_key_exit(void) 259 { 260 unregister_asymmetric_key_parser(&x509_key_parser); 261 } 262 263 module_init(x509_key_init); 264 module_exit(x509_key_exit); 265 266 MODULE_DESCRIPTION("X.509 certificate parser"); 267 MODULE_AUTHOR("Red Hat, Inc."); 268 MODULE_LICENSE("GPL"); 269