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 <crypto/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 char *const pkey_id_type_name[PKEY_ID_TYPE__LAST] = {
  32         [PKEY_ID_PGP]           = "PGP",
  33         [PKEY_ID_X509]          = "X509",
  34         [PKEY_ID_PKCS7]         = "PKCS#7",
  35 };
  36 EXPORT_SYMBOL_GPL(pkey_id_type_name);
  37
  38 static int (*alg_verify[PKEY_ALGO__LAST])(const struct public_key *pkey,
  39         const struct public_key_signature *sig) = {
  40         NULL,
  41         rsa_verify_signature
  42 };
  43
  44 /*
  45  * Provide a part of a description of the key for /proc/keys.
  46  */
  47 static void public_key_describe(const struct key *asymmetric_key,
  48                                 struct seq_file *m)
  49 {
  50         struct public_key *key = asymmetric_key->payload.data[asym_crypto];
  51
  52         if (key)
  53                 seq_printf(m, "%s.%s",
  54                            pkey_id_type_name[key->id_type],
  55                            pkey_algo_name[key->pkey_algo]);
  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
  65         if (key)
  66                 kfree(key->key);
  67         kfree(key);
  68 }
  69 EXPORT_SYMBOL_GPL(public_key_destroy);
  70
  71 /*
  72  * Verify a signature using a public key.
  73  */
  74 int public_key_verify_signature(const struct public_key *pkey,
  75                                 const struct public_key_signature *sig)
  76 {
  77         BUG_ON(!pkey);
  78         BUG_ON(!sig);
  79         BUG_ON(!sig->digest);
  80         BUG_ON(!sig->s);
  81
  82         if (pkey->pkey_algo >= PKEY_ALGO__LAST)
  83                 return -ENOPKG;
  84
  85         if (!alg_verify[pkey->pkey_algo])
  86                 return -ENOPKG;
  87
  88         return alg_verify[pkey->pkey_algo](pkey, sig);
  89 }
  90 EXPORT_SYMBOL_GPL(public_key_verify_signature);
  91
  92 static int public_key_verify_signature_2(const struct key *key,
  93                                          const struct public_key_signature *sig)
  94 {
  95         const struct public_key *pk = key->payload.data[asym_crypto];
  96         return public_key_verify_signature(pk, sig);
  97 }
  98
  99 /*
 100  * Public key algorithm asymmetric key subtype
 101  */
 102 struct asymmetric_key_subtype public_key_subtype = {
 103         .owner                  = THIS_MODULE,
 104         .name                   = "public_key",
 105         .name_len               = sizeof("public_key") - 1,
 106         .describe               = public_key_describe,
 107         .destroy                = public_key_destroy,
 108         .verify_signature       = public_key_verify_signature_2,
 109 };
 110 EXPORT_SYMBOL_GPL(public_key_subtype);