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