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 #include <linux/err.h>
  10 #include <linux/sched.h>
  11 #include <linux/slab.h>
  12 #include <linux/cred.h>
  13 #include <linux/kernel_read_file.h>
  14 #include <linux/key-type.h>
  15 #include <linux/digsig.h>
  16 #include <linux/vmalloc.h>
  17 #include <crypto/public_key.h>
  18 #include <keys/system_keyring.h>
  19
  20 #include "integrity.h"
  21
  22 static struct key *keyring[INTEGRITY_KEYRING_MAX];
  23
  24 static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
  25 #ifndef CONFIG_INTEGRITY_TRUSTED_KEYRING
  26         "_evm",
  27         "_ima",
  28 #else
  29         ".evm",
  30         ".ima",
  31 #endif
  32         ".platform",
  33 };
  34
  35 #ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
  36 #define restrict_link_to_ima restrict_link_by_builtin_and_secondary_trusted
  37 #else
  38 #define restrict_link_to_ima restrict_link_by_builtin_trusted
  39 #endif
  40
  41 static struct key *integrity_keyring_from_id(const unsigned int id)
  42 {
  43         if (id >= INTEGRITY_KEYRING_MAX)
  44                 return ERR_PTR(-EINVAL);
  45
  46         if (!keyring[id]) {
  47                 keyring[id] =
  48                         request_key(&key_type_keyring, keyring_name[id], NULL);
  49                 if (IS_ERR(keyring[id])) {
  50                         int err = PTR_ERR(keyring[id]);
  51                         pr_err("no %s keyring: %d\n", keyring_name[id], err);
  52                         keyring[id] = NULL;
  53                         return ERR_PTR(err);
  54                 }
  55         }
  56
  57         return keyring[id];
  58 }
  59
  60 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
  61                             const char *digest, int digestlen)
  62 {
  63         struct key *keyring;
  64
  65         if (siglen < 2)
  66                 return -EINVAL;
  67
  68         keyring = integrity_keyring_from_id(id);
  69         if (IS_ERR(keyring))
  70                 return PTR_ERR(keyring);
  71
  72         switch (sig[1]) {
  73         case 1:
  74                 /* v1 API expect signature without xattr type */
  75                 return digsig_verify(keyring, sig + 1, siglen - 1, digest,
  76                                      digestlen);
  77         case 2:
  78                 return asymmetric_verify(keyring, sig, siglen, digest,
  79                                          digestlen);
  80         }
  81
  82         return -EOPNOTSUPP;
  83 }
  84
  85 int integrity_modsig_verify(const unsigned int id, const struct modsig *modsig)
  86 {
  87         struct key *keyring;
  88
  89         keyring = integrity_keyring_from_id(id);
  90         if (IS_ERR(keyring))
  91                 return PTR_ERR(keyring);
  92
  93         return ima_modsig_verify(keyring, modsig);
  94 }
  95
  96 static int __init __integrity_init_keyring(const unsigned int id,
  97                                            key_perm_t perm,
  98                                            struct key_restriction *restriction)
  99 {
 100         const struct cred *cred = current_cred();
 101         int err = 0;
 102
 103         keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
 104                                     KGIDT_INIT(0), cred, perm,
 105                                     KEY_ALLOC_NOT_IN_QUOTA, restriction, NULL);
 106         if (IS_ERR(keyring[id])) {
 107                 err = PTR_ERR(keyring[id]);
 108                 pr_info("Can't allocate %s keyring (%d)\n",
 109                         keyring_name[id], err);
 110                 keyring[id] = NULL;
 111         } else {
 112                 if (id == INTEGRITY_KEYRING_PLATFORM)
 113                         set_platform_trusted_keys(keyring[id]);
 114                 if (id == INTEGRITY_KEYRING_IMA)
 115                         load_module_cert(keyring[id]);
 116         }
 117
 118         return err;
 119 }
 120
 121 int __init integrity_init_keyring(const unsigned int id)
 122 {
 123         struct key_restriction *restriction;
 124         key_perm_t perm;
 125
 126         perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW
 127                 | KEY_USR_READ | KEY_USR_SEARCH;
 128
 129         if (id == INTEGRITY_KEYRING_PLATFORM) {
 130                 restriction = NULL;
 131                 goto out;
 132         }
 133
 134         if (!IS_ENABLED(CONFIG_INTEGRITY_TRUSTED_KEYRING))
 135                 return 0;
 136
 137         restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
 138         if (!restriction)
 139                 return -ENOMEM;
 140
 141         restriction->check = restrict_link_to_ima;
 142         perm |= KEY_USR_WRITE;
 143
 144 out:
 145         return __integrity_init_keyring(id, perm, restriction);
 146 }
 147
 148 static int __init integrity_add_key(const unsigned int id, const void *data,
 149                                     off_t size, key_perm_t perm)
 150 {
 151         key_ref_t key;
 152         int rc = 0;
 153
 154         if (!keyring[id])
 155                 return -EINVAL;
 156
 157         key = key_create_or_update(make_key_ref(keyring[id], 1), "asymmetric",
 158                                    NULL, data, size, perm,
 159                                    KEY_ALLOC_NOT_IN_QUOTA);
 160         if (IS_ERR(key)) {
 161                 rc = PTR_ERR(key);
 162                 pr_err("Problem loading X.509 certificate %d\n", rc);
 163         } else {
 164                 pr_notice("Loaded X.509 cert '%s'\n",
 165                           key_ref_to_ptr(key)->description);
 166                 key_ref_put(key);
 167         }
 168
 169         return rc;
 170
 171 }
 172
 173 int __init integrity_load_x509(const unsigned int id, const char *path)
 174 {
 175         void *data = NULL;
 176         size_t size;
 177         int rc;
 178         key_perm_t perm;
 179
 180         rc = kernel_read_file_from_path(path, 0, &data, INT_MAX, NULL,
 181                                         READING_X509_CERTIFICATE);
 182         if (rc < 0) {
 183                 pr_err("Unable to open file: %s (%d)", path, rc);
 184                 return rc;
 185         }
 186         size = rc;
 187
 188         perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW | KEY_USR_READ;
 189
 190         pr_info("Loading X.509 certificate: %s\n", path);
 191         rc = integrity_add_key(id, (const void *)data, size, perm);
 192
 193         vfree(data);
 194         return rc;
 195 }
 196
 197 int __init integrity_load_cert(const unsigned int id, const char *source,
 198                                const void *data, size_t len, key_perm_t perm)
 199 {
 200         if (!data)
 201                 return -EINVAL;
 202
 203         pr_info("Loading X.509 certificate: %s\n", source);
 204         return integrity_add_key(id, data, len, perm);
 205 }