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