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/slab.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 #ifndef CONFIG_INTEGRITY_TRUSTED_KEYRING
  28         "_evm",
  29         "_ima",
  30 #else
  31         ".evm",
  32         ".ima",
  33 #endif
  34         "_module",
  35 };
  36
  37 #ifdef CONFIG_INTEGRITY_TRUSTED_KEYRING
  38 static bool init_keyring __initdata = true;
  39 #else
  40 static bool init_keyring __initdata;
  41 #endif
  42
  43 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
  44                             const char *digest, int digestlen)
  45 {
  46         if (id >= INTEGRITY_KEYRING_MAX)
  47                 return -EINVAL;
  48
  49         if (!keyring[id]) {
  50                 keyring[id] =
  51                         request_key(&key_type_keyring, keyring_name[id], NULL);
  52                 if (IS_ERR(keyring[id])) {
  53                         int err = PTR_ERR(keyring[id]);
  54                         pr_err("no %s keyring: %d\n", keyring_name[id], err);
  55                         keyring[id] = NULL;
  56                         return err;
  57                 }
  58         }
  59
  60         switch (sig[1]) {
  61         case 1:
  62                 /* v1 API expect signature without xattr type */
  63                 return digsig_verify(keyring[id], sig + 1, siglen - 1,
  64                                      digest, digestlen);
  65         case 2:
  66                 return asymmetric_verify(keyring[id], sig, siglen,
  67                                          digest, digestlen);
  68         }
  69
  70         return -EOPNOTSUPP;
  71 }
  72
  73 int __init integrity_init_keyring(const unsigned int id)
  74 {
  75         const struct cred *cred = current_cred();
  76         int err = 0;
  77
  78         if (!init_keyring)
  79                 return 0;
  80
  81         keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
  82                                     KGIDT_INIT(0), cred,
  83                                     ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
  84                                      KEY_USR_VIEW | KEY_USR_READ |
  85                                      KEY_USR_WRITE | KEY_USR_SEARCH),
  86                                     KEY_ALLOC_NOT_IN_QUOTA, NULL);
  87         if (!IS_ERR(keyring[id]))
  88                 set_bit(KEY_FLAG_TRUSTED_ONLY, &keyring[id]->flags);
  89         else {
  90                 err = PTR_ERR(keyring[id]);
  91                 pr_info("Can't allocate %s keyring (%d)\n",
  92                         keyring_name[id], err);
  93                 keyring[id] = NULL;
  94         }
  95         return err;
  96 }
  97
  98 int __init integrity_load_x509(const unsigned int id, const char *path)
  99 {
 100         key_ref_t key;
 101         char *data;
 102         int rc;
 103
 104         if (!keyring[id])
 105                 return -EINVAL;
 106
 107         rc = integrity_read_file(path, &data);
 108         if (rc < 0)
 109                 return rc;
 110
 111         key = key_create_or_update(make_key_ref(keyring[id], 1),
 112                                    "asymmetric",
 113                                    NULL,
 114                                    data,
 115                                    rc,
 116                                    ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
 117                                     KEY_USR_VIEW | KEY_USR_READ),
 118                                    KEY_ALLOC_NOT_IN_QUOTA);
 119         if (IS_ERR(key)) {
 120                 rc = PTR_ERR(key);
 121                 pr_err("Problem loading X.509 certificate (%d): %s\n",
 122                        rc, path);
 123         } else {
 124                 pr_notice("Loaded X.509 cert '%s': %s\n",
 125                           key_ref_to_ptr(key)->description, path);
 126                 key_ref_put(key);
 127         }
 128         kfree(data);
 129         return 0;
 130 }