crypto/asymmetric_keys/public_key.c

   1 /* In-software asymmetric public-key crypto subtype
   2  *
   3  * See Documentation/crypto/asymmetric-keys.txt
   4  *
   5  * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
   6  * Written by David Howells (dhowells@redhat.com)
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public Licence
  10  * as published by the Free Software Foundation; either version
  11  * 2 of the Licence, or (at your option) any later version.
  12  */
  13
  14 #define pr_fmt(fmt) "PKEY: "fmt
  15 #include <linux/module.h>
  16 #include <linux/export.h>
  17 #include <linux/kernel.h>
  18 #include <linux/slab.h>
  19 #include <linux/seq_file.h>
  20 #include <keys/asymmetric-subtype.h>
  21 #include "public_key.h"
  22
  23 MODULE_LICENSE("GPL");
  24
  25 const char *const pkey_algo_name[PKEY_ALGO__LAST] = {
  26         [PKEY_ALGO_DSA]         = "DSA",
  27         [PKEY_ALGO_RSA]         = "RSA",
  28 };
  29 EXPORT_SYMBOL_GPL(pkey_algo_name);
  30
  31 const struct public_key_algorithm *pkey_algo[PKEY_ALGO__LAST] = {
  32 #if defined(CONFIG_PUBLIC_KEY_ALGO_RSA) || \
  33         defined(CONFIG_PUBLIC_KEY_ALGO_RSA_MODULE)
  34         [PKEY_ALGO_RSA]         = &RSA_public_key_algorithm,
  35 #endif
  36 };
  37 EXPORT_SYMBOL_GPL(pkey_algo);
  38
  39 const char *const pkey_hash_algo_name[PKEY_HASH__LAST] = {
  40         [PKEY_HASH_MD4]         = "md4",
  41         [PKEY_HASH_MD5]         = "md5",
  42         [PKEY_HASH_SHA1]        = "sha1",
  43         [PKEY_HASH_RIPE_MD_160] = "rmd160",
  44         [PKEY_HASH_SHA256]      = "sha256",
  45         [PKEY_HASH_SHA384]      = "sha384",
  46         [PKEY_HASH_SHA512]      = "sha512",
  47         [PKEY_HASH_SHA224]      = "sha224",
  48 };
  49 EXPORT_SYMBOL_GPL(pkey_hash_algo_name);
  50
  51 const char *const pkey_id_type_name[PKEY_ID_TYPE__LAST] = {
  52         [PKEY_ID_PGP]           = "PGP",
  53         [PKEY_ID_X509]          = "X509",
  54 };
  55 EXPORT_SYMBOL_GPL(pkey_id_type_name);
  56
  57 /*
  58  * Provide a part of a description of the key for /proc/keys.
  59  */
  60 static void public_key_describe(const struct key *asymmetric_key,
  61                                 struct seq_file *m)
  62 {
  63         struct public_key *key = asymmetric_key->payload.data;
  64
  65         if (key)
  66                 seq_printf(m, "%s.%s",
  67                            pkey_id_type_name[key->id_type], key->algo->name);
  68 }
  69
  70 /*
  71  * Destroy a public key algorithm key.
  72  */
  73 void public_key_destroy(void *payload)
  74 {
  75         struct public_key *key = payload;
  76         int i;
  77
  78         if (key) {
  79                 for (i = 0; i < ARRAY_SIZE(key->mpi); i++)
  80                         mpi_free(key->mpi[i]);
  81                 kfree(key);
  82         }
  83 }
  84 EXPORT_SYMBOL_GPL(public_key_destroy);
  85
  86 /*
  87  * Verify a signature using a public key.
  88  */
  89 int public_key_verify_signature(const struct public_key *pk,
  90                                 const struct public_key_signature *sig)
  91 {
  92         const struct public_key_algorithm *algo;
  93
  94         BUG_ON(!pk);
  95         BUG_ON(!pk->mpi[0]);
  96         BUG_ON(!pk->mpi[1]);
  97         BUG_ON(!sig);
  98         BUG_ON(!sig->digest);
  99         BUG_ON(!sig->mpi[0]);
 100
 101         algo = pk->algo;
 102         if (!algo) {
 103                 if (pk->pkey_algo >= PKEY_ALGO__LAST)
 104                         return -ENOPKG;
 105                 algo = pkey_algo[pk->pkey_algo];
 106                 if (!algo)
 107                         return -ENOPKG;
 108         }
 109
 110         if (!algo->verify_signature)
 111                 return -ENOTSUPP;
 112
 113         if (sig->nr_mpi != algo->n_sig_mpi) {
 114                 pr_debug("Signature has %u MPI not %u\n",
 115                          sig->nr_mpi, algo->n_sig_mpi);
 116                 return -EINVAL;
 117         }
 118
 119         return algo->verify_signature(pk, sig);
 120 }
 121 EXPORT_SYMBOL_GPL(public_key_verify_signature);
 122
 123 static int public_key_verify_signature_2(const struct key *key,
 124                                          const struct public_key_signature *sig)
 125 {
 126         const struct public_key *pk = key->payload.data;
 127         return public_key_verify_signature(pk, sig);
 128 }
 129
 130 /*
 131  * Public key algorithm asymmetric key subtype
 132  */
 133 struct asymmetric_key_subtype public_key_subtype = {
 134         .owner                  = THIS_MODULE,
 135         .name                   = "public_key",
 136         .describe               = public_key_describe,
 137         .destroy                = public_key_destroy,
 138         .verify_signature       = public_key_verify_signature_2,
 139 };
 140 EXPORT_SYMBOL_GPL(public_key_subtype);