security/integrity/digsig.c

   1 /*
   2  * Copyright (C) 2011 Intel Corporation
   3  *
   4  * Author:
   5  * Dmitry Kasatkin <dmitry.kasatkin@intel.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation, version 2 of the License.
  10  *
  11  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15 #include <linux/err.h>
  16 #include <linux/sched.h>
  17 #include <linux/rbtree.h>
  18 #include <linux/cred.h>
  19 #include <linux/key-type.h>
  20 #include <linux/digsig.h>
  21
  22 #include "integrity.h"
  23
  24 static struct key *keyring[INTEGRITY_KEYRING_MAX];
  25
  26 static const char *keyring_name[INTEGRITY_KEYRING_MAX] = {
  27         "_evm",
  28         "_module",
  29 #ifndef CONFIG_IMA_TRUSTED_KEYRING
  30         "_ima",
  31 #else
  32         ".ima",
  33 #endif
  34 };
  35
  36 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
  37                             const char *digest, int digestlen)
  38 {
  39         if (id >= INTEGRITY_KEYRING_MAX)
  40                 return -EINVAL;
  41
  42         if (!keyring[id]) {
  43                 keyring[id] =
  44                         request_key(&key_type_keyring, keyring_name[id], NULL);
  45                 if (IS_ERR(keyring[id])) {
  46                         int err = PTR_ERR(keyring[id]);
  47                         pr_err("no %s keyring: %d\n", keyring_name[id], err);
  48                         keyring[id] = NULL;
  49                         return err;
  50                 }
  51         }
  52
  53         switch (sig[1]) {
  54         case 1:
  55                 /* v1 API expect signature without xattr type */
  56                 return digsig_verify(keyring[id], sig + 1, siglen - 1,
  57                                      digest, digestlen);
  58         case 2:
  59                 return asymmetric_verify(keyring[id], sig, siglen,
  60                                          digest, digestlen);
  61         }
  62
  63         return -EOPNOTSUPP;
  64 }
  65
  66 int integrity_init_keyring(const unsigned int id)
  67 {
  68         const struct cred *cred = current_cred();
  69         int err = 0;
  70
  71         keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
  72                                     KGIDT_INIT(0), cred,
  73                                     ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
  74                                      KEY_USR_VIEW | KEY_USR_READ |
  75                                      KEY_USR_WRITE | KEY_USR_SEARCH),
  76                                     KEY_ALLOC_NOT_IN_QUOTA, NULL);
  77         if (!IS_ERR(keyring[id]))
  78                 set_bit(KEY_FLAG_TRUSTED_ONLY, &keyring[id]->flags);
  79         else {
  80                 err = PTR_ERR(keyring[id]);
  81                 pr_info("Can't allocate %s keyring (%d)\n",
  82                         keyring_name[id], err);
  83                 keyring[id] = NULL;
  84         }
  85         return err;
  86 }