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 <crypto/public_key.h>
  22 #include <keys/system_keyring.h>
  23
  24 #include "integrity.h"
  25
  26 static struct key *keyring[INTEGRITY_KEYRING_MAX];
  27
  28 static const char *keyring_name[INTEGRITY_KEYRING_MAX] = {
  29 #ifndef CONFIG_INTEGRITY_TRUSTED_KEYRING
  30         "_evm",
  31         "_ima",
  32 #else
  33         ".evm",
  34         ".ima",
  35 #endif
  36         "_module",
  37 };
  38
  39 #ifdef CONFIG_INTEGRITY_TRUSTED_KEYRING
  40 static bool init_keyring __initdata = true;
  41 #else
  42 static bool init_keyring __initdata;
  43 #endif
  44
  45 #ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
  46 #define restrict_link_to_ima restrict_link_by_builtin_and_secondary_trusted
  47 #else
  48 #define restrict_link_to_ima restrict_link_by_builtin_trusted
  49 #endif
  50
  51 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
  52                             const char *digest, int digestlen)
  53 {
  54         if (id >= INTEGRITY_KEYRING_MAX || siglen < 2)
  55                 return -EINVAL;
  56
  57         if (!keyring[id]) {
  58                 keyring[id] =
  59                         request_key(&key_type_keyring, keyring_name[id], NULL);
  60                 if (IS_ERR(keyring[id])) {
  61                         int err = PTR_ERR(keyring[id]);
  62                         pr_err("no %s keyring: %d\n", keyring_name[id], err);
  63                         keyring[id] = NULL;
  64                         return err;
  65                 }
  66         }
  67
  68         switch (sig[1]) {
  69         case 1:
  70                 /* v1 API expect signature without xattr type */
  71                 return digsig_verify(keyring[id], sig + 1, siglen - 1,
  72                                      digest, digestlen);
  73         case 2:
  74                 return asymmetric_verify(keyring[id], sig, siglen,
  75                                          digest, digestlen);
  76         }
  77
  78         return -EOPNOTSUPP;
  79 }
  80
  81 int __init integrity_init_keyring(const unsigned int id)
  82 {
  83         const struct cred *cred = current_cred();
  84         struct key_restriction *restriction;
  85         int err = 0;
  86
  87         if (!init_keyring)
  88                 return 0;
  89
  90         restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
  91         if (!restriction)
  92                 return -ENOMEM;
  93
  94         restriction->check = restrict_link_to_ima;
  95
  96         keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
  97                                     KGIDT_INIT(0), cred,
  98                                     ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
  99                                      KEY_USR_VIEW | KEY_USR_READ |
 100                                      KEY_USR_WRITE | KEY_USR_SEARCH),
 101                                     KEY_ALLOC_NOT_IN_QUOTA,
 102                                     restriction, NULL);
 103         if (IS_ERR(keyring[id])) {
 104                 err = PTR_ERR(keyring[id]);
 105                 pr_info("Can't allocate %s keyring (%d)\n",
 106                         keyring_name[id], err);
 107                 keyring[id] = NULL;
 108         }
 109         return err;
 110 }
 111
 112 int __init integrity_load_x509(const unsigned int id, const char *path)
 113 {
 114         key_ref_t key;
 115         void *data;
 116         loff_t size;
 117         int rc;
 118
 119         if (!keyring[id])
 120                 return -EINVAL;
 121
 122         rc = kernel_read_file_from_path(path, &data, &size, 0,
 123                                         READING_X509_CERTIFICATE);
 124         if (rc < 0) {
 125                 pr_err("Unable to open file: %s (%d)", path, rc);
 126                 return rc;
 127         }
 128
 129         key = key_create_or_update(make_key_ref(keyring[id], 1),
 130                                    "asymmetric",
 131                                    NULL,
 132                                    data,
 133                                    size,
 134                                    ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
 135                                     KEY_USR_VIEW | KEY_USR_READ),
 136                                    KEY_ALLOC_NOT_IN_QUOTA);
 137         if (IS_ERR(key)) {
 138                 rc = PTR_ERR(key);
 139                 pr_err("Problem loading X.509 certificate (%d): %s\n",
 140                        rc, path);
 141         } else {
 142                 pr_notice("Loaded X.509 cert '%s': %s\n",
 143                           key_ref_to_ptr(key)->description, path);
 144                 key_ref_put(key);
 145         }
 146         vfree(data);
 147         return 0;
 148 }