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         ".platform",
  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 static int __init __integrity_init_keyring(const unsigned int id,
  77                                            key_perm_t perm,
  78                                            struct key_restriction *restriction)
  79 {
  80         const struct cred *cred = current_cred();
  81         int err = 0;
  82
  83         keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
  84                                     KGIDT_INIT(0), cred, perm,
  85                                     KEY_ALLOC_NOT_IN_QUOTA, restriction, NULL);
  86         if (IS_ERR(keyring[id])) {
  87                 err = PTR_ERR(keyring[id]);
  88                 pr_info("Can't allocate %s keyring (%d)\n",
  89                         keyring_name[id], err);
  90                 keyring[id] = NULL;
  91         } else {
  92                 if (id == INTEGRITY_KEYRING_PLATFORM)
  93                         set_platform_trusted_keys(keyring[id]);
  94         }
  95
  96         return err;
  97 }
  98
  99 int __init integrity_init_keyring(const unsigned int id)
 100 {
 101         struct key_restriction *restriction;
 102         key_perm_t perm;
 103
 104         perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW
 105                 | KEY_USR_READ | KEY_USR_SEARCH;
 106
 107         if (id == INTEGRITY_KEYRING_PLATFORM) {
 108                 restriction = NULL;
 109                 goto out;
 110         }
 111
 112         if (!IS_ENABLED(CONFIG_INTEGRITY_TRUSTED_KEYRING))
 113                 return 0;
 114
 115         restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
 116         if (!restriction)
 117                 return -ENOMEM;
 118
 119         restriction->check = restrict_link_to_ima;
 120         perm |= KEY_USR_WRITE;
 121
 122 out:
 123         return __integrity_init_keyring(id, perm, restriction);
 124 }
 125
 126 int __init integrity_add_key(const unsigned int id, const void *data,
 127                              off_t size, key_perm_t perm)
 128 {
 129         key_ref_t key;
 130         int rc = 0;
 131
 132         if (!keyring[id])
 133                 return -EINVAL;
 134
 135         key = key_create_or_update(make_key_ref(keyring[id], 1), "asymmetric",
 136                                    NULL, data, size, perm,
 137                                    KEY_ALLOC_NOT_IN_QUOTA);
 138         if (IS_ERR(key)) {
 139                 rc = PTR_ERR(key);
 140                 pr_err("Problem loading X.509 certificate %d\n", rc);
 141         } else {
 142                 pr_notice("Loaded X.509 cert '%s'\n",
 143                           key_ref_to_ptr(key)->description);
 144                 key_ref_put(key);
 145         }
 146
 147         return rc;
 148
 149 }
 150
 151 int __init integrity_load_x509(const unsigned int id, const char *path)
 152 {
 153         void *data;
 154         loff_t size;
 155         int rc;
 156         key_perm_t perm;
 157
 158         rc = kernel_read_file_from_path(path, &data, &size, 0,
 159                                         READING_X509_CERTIFICATE);
 160         if (rc < 0) {
 161                 pr_err("Unable to open file: %s (%d)", path, rc);
 162                 return rc;
 163         }
 164
 165         perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW | KEY_USR_READ;
 166
 167         pr_info("Loading X.509 certificate: %s\n", path);
 168         rc = integrity_add_key(id, (const void *)data, size, perm);
 169
 170         vfree(data);
 171         return rc;
 172 }
 173
 174 int __init integrity_load_cert(const unsigned int id, const char *source,
 175                                const void *data, size_t len, key_perm_t perm)
 176 {
 177         if (!data)
 178                 return -EINVAL;
 179
 180         pr_info("Loading X.509 certificate: %s\n", source);
 181         return integrity_add_key(id, data, len, perm);
 182 }