security/integrity/digsig.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2011 Intel Corporation
   4  *
   5  * Author:
   6  * Dmitry Kasatkin <dmitry.kasatkin@intel.com>
   7  */
   8
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/err.h>
  12 #include <linux/sched.h>
  13 #include <linux/slab.h>
  14 #include <linux/cred.h>
  15 #include <linux/key-type.h>
  16 #include <linux/digsig.h>
  17 #include <linux/vmalloc.h>
  18 #include <crypto/public_key.h>
  19 #include <keys/system_keyring.h>
  20
  21 #include "integrity.h"
  22
  23 static struct key *keyring[INTEGRITY_KEYRING_MAX];
  24
  25 static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
  26 #ifndef CONFIG_INTEGRITY_TRUSTED_KEYRING
  27         "_evm",
  28         "_ima",
  29 #else
  30         ".evm",
  31         ".ima",
  32 #endif
  33         ".platform",
  34 };
  35
  36 #ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
  37 #define restrict_link_to_ima restrict_link_by_builtin_and_secondary_trusted
  38 #else
  39 #define restrict_link_to_ima restrict_link_by_builtin_trusted
  40 #endif
  41
  42 static struct key *integrity_keyring_from_id(const unsigned int id)
  43 {
  44         if (id >= INTEGRITY_KEYRING_MAX)
  45                 return ERR_PTR(-EINVAL);
  46
  47         if (!keyring[id]) {
  48                 keyring[id] =
  49                         request_key(&key_type_keyring, keyring_name[id], NULL);
  50                 if (IS_ERR(keyring[id])) {
  51                         int err = PTR_ERR(keyring[id]);
  52                         pr_err("no %s keyring: %d\n", keyring_name[id], err);
  53                         keyring[id] = NULL;
  54                         return ERR_PTR(err);
  55                 }
  56         }
  57
  58         return keyring[id];
  59 }
  60
  61 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
  62                             const char *digest, int digestlen)
  63 {
  64         struct key *keyring;
  65
  66         if (siglen < 2)
  67                 return -EINVAL;
  68
  69         keyring = integrity_keyring_from_id(id);
  70         if (IS_ERR(keyring))
  71                 return PTR_ERR(keyring);
  72
  73         switch (sig[1]) {
  74         case 1:
  75                 /* v1 API expect signature without xattr type */
  76                 return digsig_verify(keyring, sig + 1, siglen - 1, digest,
  77                                      digestlen);
  78         case 2:
  79                 return asymmetric_verify(keyring, sig, siglen, digest,
  80                                          digestlen);
  81         }
  82
  83         return -EOPNOTSUPP;
  84 }
  85
  86 int integrity_modsig_verify(const unsigned int id, const struct modsig *modsig)
  87 {
  88         struct key *keyring;
  89
  90         keyring = integrity_keyring_from_id(id);
  91         if (IS_ERR(keyring))
  92                 return PTR_ERR(keyring);
  93
  94         return ima_modsig_verify(keyring, modsig);
  95 }
  96
  97 static int __init __integrity_init_keyring(const unsigned int id,
  98                                            key_perm_t perm,
  99                                            struct key_restriction *restriction)
 100 {
 101         const struct cred *cred = current_cred();
 102         int err = 0;
 103
 104         keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
 105                                     KGIDT_INIT(0), cred, perm,
 106                                     KEY_ALLOC_NOT_IN_QUOTA, restriction, NULL);
 107         if (IS_ERR(keyring[id])) {
 108                 err = PTR_ERR(keyring[id]);
 109                 pr_info("Can't allocate %s keyring (%d)\n",
 110                         keyring_name[id], err);
 111                 keyring[id] = NULL;
 112         } else {
 113                 if (id == INTEGRITY_KEYRING_PLATFORM)
 114                         set_platform_trusted_keys(keyring[id]);
 115         }
 116
 117         return err;
 118 }
 119
 120 int __init integrity_init_keyring(const unsigned int id)
 121 {
 122         struct key_restriction *restriction;
 123         key_perm_t perm;
 124
 125         perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW
 126                 | KEY_USR_READ | KEY_USR_SEARCH;
 127
 128         if (id == INTEGRITY_KEYRING_PLATFORM) {
 129                 restriction = NULL;
 130                 goto out;
 131         }
 132
 133         if (!IS_ENABLED(CONFIG_INTEGRITY_TRUSTED_KEYRING))
 134                 return 0;
 135
 136         restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
 137         if (!restriction)
 138                 return -ENOMEM;
 139
 140         restriction->check = restrict_link_to_ima;
 141         perm |= KEY_USR_WRITE;
 142
 143 out:
 144         return __integrity_init_keyring(id, perm, restriction);
 145 }
 146
 147 int __init integrity_add_key(const unsigned int id, const void *data,
 148                              off_t size, key_perm_t perm)
 149 {
 150         key_ref_t key;
 151         int rc = 0;
 152
 153         if (!keyring[id])
 154                 return -EINVAL;
 155
 156         key = key_create_or_update(make_key_ref(keyring[id], 1), "asymmetric",
 157                                    NULL, data, size, perm,
 158                                    KEY_ALLOC_NOT_IN_QUOTA);
 159         if (IS_ERR(key)) {
 160                 rc = PTR_ERR(key);
 161                 pr_err("Problem loading X.509 certificate %d\n", rc);
 162         } else {
 163                 pr_notice("Loaded X.509 cert '%s'\n",
 164                           key_ref_to_ptr(key)->description);
 165                 key_ref_put(key);
 166         }
 167
 168         return rc;
 169
 170 }
 171
 172 int __init integrity_load_x509(const unsigned int id, const char *path)
 173 {
 174         void *data;
 175         loff_t size;
 176         int rc;
 177         key_perm_t perm;
 178
 179         rc = kernel_read_file_from_path(path, &data, &size, 0,
 180                                         READING_X509_CERTIFICATE);
 181         if (rc < 0) {
 182                 pr_err("Unable to open file: %s (%d)", path, rc);
 183                 return rc;
 184         }
 185
 186         perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW | KEY_USR_READ;
 187
 188         pr_info("Loading X.509 certificate: %s\n", path);
 189         rc = integrity_add_key(id, (const void *)data, size, perm);
 190
 191         vfree(data);
 192         return rc;
 193 }
 194
 195 int __init integrity_load_cert(const unsigned int id, const char *source,
 196                                const void *data, size_t len, key_perm_t perm)
 197 {
 198         if (!data)
 199                 return -EINVAL;
 200
 201         pr_info("Loading X.509 certificate: %s\n", source);
 202         return integrity_add_key(id, data, len, perm);
 203 }