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 #include <linux/vmalloc.h>
  22 #include <crypto/public_key.h>
  23 #include <keys/system_keyring.h>
  24
  25 #include "integrity.h"
  26
  27 static struct key *keyring[INTEGRITY_KEYRING_MAX];
  28
  29 static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
  30 #ifndef CONFIG_INTEGRITY_TRUSTED_KEYRING
  31         "_evm",
  32         "_ima",
  33 #else
  34         ".evm",
  35         ".ima",
  36 #endif
  37         "_module",
  38 };
  39
  40 #ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
  41 #define restrict_link_to_ima restrict_link_by_builtin_and_secondary_trusted
  42 #else
  43 #define restrict_link_to_ima restrict_link_by_builtin_trusted
  44 #endif
  45
  46 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
  47                             const char *digest, int digestlen)
  48 {
  49         if (id >= INTEGRITY_KEYRING_MAX || siglen < 2)
  50                 return -EINVAL;
  51
  52         if (!keyring[id]) {
  53                 keyring[id] =
  54                         request_key(&key_type_keyring, keyring_name[id], NULL);
  55                 if (IS_ERR(keyring[id])) {
  56                         int err = PTR_ERR(keyring[id]);
  57                         pr_err("no %s keyring: %d\n", keyring_name[id], err);
  58                         keyring[id] = NULL;
  59                         return err;
  60                 }
  61         }
  62
  63         switch (sig[1]) {
  64         case 1:
  65                 /* v1 API expect signature without xattr type */
  66                 return digsig_verify(keyring[id], sig + 1, siglen - 1,
  67                                      digest, digestlen);
  68         case 2:
  69                 return asymmetric_verify(keyring[id], sig, siglen,
  70                                          digest, digestlen);
  71         }
  72
  73         return -EOPNOTSUPP;
  74 }
  75
  76 int __init integrity_init_keyring(const unsigned int id)
  77 {
  78         const struct cred *cred = current_cred();
  79         struct key_restriction *restriction;
  80         int err = 0;
  81
  82         if (!IS_ENABLED(CONFIG_INTEGRITY_TRUSTED_KEYRING))
  83                 return 0;
  84
  85         restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
  86         if (!restriction)
  87                 return -ENOMEM;
  88
  89         restriction->check = restrict_link_to_ima;
  90
  91         keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
  92                                     KGIDT_INIT(0), cred,
  93                                     ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
  94                                      KEY_USR_VIEW | KEY_USR_READ |
  95                                      KEY_USR_WRITE | KEY_USR_SEARCH),
  96                                     KEY_ALLOC_NOT_IN_QUOTA,
  97                                     restriction, NULL);
  98         if (IS_ERR(keyring[id])) {
  99                 err = PTR_ERR(keyring[id]);
 100                 pr_info("Can't allocate %s keyring (%d)\n",
 101                         keyring_name[id], err);
 102                 keyring[id] = NULL;
 103         }
 104         return err;
 105 }
 106
 107 int __init integrity_load_x509(const unsigned int id, const char *path)
 108 {
 109         key_ref_t key;
 110         void *data;
 111         loff_t size;
 112         int rc;
 113
 114         if (!keyring[id])
 115                 return -EINVAL;
 116
 117         rc = kernel_read_file_from_path(path, &data, &size, 0,
 118                                         READING_X509_CERTIFICATE);
 119         if (rc < 0) {
 120                 pr_err("Unable to open file: %s (%d)", path, rc);
 121                 return rc;
 122         }
 123
 124         key = key_create_or_update(make_key_ref(keyring[id], 1),
 125                                    "asymmetric",
 126                                    NULL,
 127                                    data,
 128                                    size,
 129                                    ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
 130                                     KEY_USR_VIEW | KEY_USR_READ),
 131                                    KEY_ALLOC_NOT_IN_QUOTA);
 132         if (IS_ERR(key)) {
 133                 rc = PTR_ERR(key);
 134                 pr_err("Problem loading X.509 certificate (%d): %s\n",
 135                        rc, path);
 136         } else {
 137                 pr_notice("Loaded X.509 cert '%s': %s\n",
 138                           key_ref_to_ptr(key)->description, path);
 139                 key_ref_put(key);
 140         }
 141         vfree(data);
 142         return 0;
 143 }