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_id_type_name[PKEY_ID_TYPE__LAST] = {
  40         [PKEY_ID_PGP]           = "PGP",
  41         [PKEY_ID_X509]          = "X509",
  42         [PKEY_ID_PKCS7]         = "PKCS#7",
  43 };
  44 EXPORT_SYMBOL_GPL(pkey_id_type_name);
  45
  46 /*
  47  * Provide a part of a description of the key for /proc/keys.
  48  */
  49 static void public_key_describe(const struct key *asymmetric_key,
  50                                 struct seq_file *m)
  51 {
  52         struct public_key *key = asymmetric_key->payload.data;
  53
  54         if (key)
  55                 seq_printf(m, "%s.%s",
  56                            pkey_id_type_name[key->id_type], key->algo->name);
  57 }
  58
  59 /*
  60  * Destroy a public key algorithm key.
  61  */
  62 void public_key_destroy(void *payload)
  63 {
  64         struct public_key *key = payload;
  65         int i;
  66
  67         if (key) {
  68                 for (i = 0; i < ARRAY_SIZE(key->mpi); i++)
  69                         mpi_free(key->mpi[i]);
  70                 kfree(key);
  71         }
  72 }
  73 EXPORT_SYMBOL_GPL(public_key_destroy);
  74
  75 /*
  76  * Verify a signature using a public key.
  77  */
  78 int public_key_verify_signature(const struct public_key *pk,
  79                                 const struct public_key_signature *sig)
  80 {
  81         const struct public_key_algorithm *algo;
  82
  83         BUG_ON(!pk);
  84         BUG_ON(!pk->mpi[0]);
  85         BUG_ON(!pk->mpi[1]);
  86         BUG_ON(!sig);
  87         BUG_ON(!sig->digest);
  88         BUG_ON(!sig->mpi[0]);
  89
  90         algo = pk->algo;
  91         if (!algo) {
  92                 if (pk->pkey_algo >= PKEY_ALGO__LAST)
  93                         return -ENOPKG;
  94                 algo = pkey_algo[pk->pkey_algo];
  95                 if (!algo)
  96                         return -ENOPKG;
  97         }
  98
  99         if (!algo->verify_signature)
 100                 return -ENOTSUPP;
 101
 102         if (sig->nr_mpi != algo->n_sig_mpi) {
 103                 pr_debug("Signature has %u MPI not %u\n",
 104                          sig->nr_mpi, algo->n_sig_mpi);
 105                 return -EINVAL;
 106         }
 107
 108         return algo->verify_signature(pk, sig);
 109 }
 110 EXPORT_SYMBOL_GPL(public_key_verify_signature);
 111
 112 static int public_key_verify_signature_2(const struct key *key,
 113                                          const struct public_key_signature *sig)
 114 {
 115         const struct public_key *pk = key->payload.data;
 116         return public_key_verify_signature(pk, sig);
 117 }
 118
 119 /*
 120  * Public key algorithm asymmetric key subtype
 121  */
 122 struct asymmetric_key_subtype public_key_subtype = {
 123         .owner                  = THIS_MODULE,
 124         .name                   = "public_key",
 125         .name_len               = sizeof("public_key") - 1,
 126         .describe               = public_key_describe,
 127         .destroy                = public_key_destroy,
 128         .verify_signature       = public_key_verify_signature_2,
 129 };
 130 EXPORT_SYMBOL_GPL(public_key_subtype);