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 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
  43                             const char *digest, int digestlen)
  44 {
  45         if (id >= INTEGRITY_KEYRING_MAX || siglen < 2)
  46                 return -EINVAL;
  47
  48         if (!keyring[id]) {
  49                 keyring[id] =
  50                         request_key(&key_type_keyring, keyring_name[id], NULL);
  51                 if (IS_ERR(keyring[id])) {
  52                         int err = PTR_ERR(keyring[id]);
  53                         pr_err("no %s keyring: %d\n", keyring_name[id], err);
  54                         keyring[id] = NULL;
  55                         return err;
  56                 }
  57         }
  58
  59         switch (sig[1]) {
  60         case 1:
  61                 /* v1 API expect signature without xattr type */
  62                 return digsig_verify(keyring[id], sig + 1, siglen - 1,
  63                                      digest, digestlen);
  64         case 2:
  65                 return asymmetric_verify(keyring[id], sig, siglen,
  66                                          digest, digestlen);
  67         }
  68
  69         return -EOPNOTSUPP;
  70 }
  71
  72 static int __integrity_init_keyring(const unsigned int id, key_perm_t perm,
  73                                     struct key_restriction *restriction)
  74 {
  75         const struct cred *cred = current_cred();
  76         int err = 0;
  77
  78         keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
  79                                     KGIDT_INIT(0), cred, perm,
  80                                     KEY_ALLOC_NOT_IN_QUOTA, restriction, NULL);
  81         if (IS_ERR(keyring[id])) {
  82                 err = PTR_ERR(keyring[id]);
  83                 pr_info("Can't allocate %s keyring (%d)\n",
  84                         keyring_name[id], err);
  85                 keyring[id] = NULL;
  86         } else {
  87                 if (id == INTEGRITY_KEYRING_PLATFORM)
  88                         set_platform_trusted_keys(keyring[id]);
  89         }
  90
  91         return err;
  92 }
  93
  94 int __init integrity_init_keyring(const unsigned int id)
  95 {
  96         struct key_restriction *restriction;
  97         key_perm_t perm;
  98
  99         perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW
 100                 | KEY_USR_READ | KEY_USR_SEARCH;
 101
 102         if (id == INTEGRITY_KEYRING_PLATFORM) {
 103                 restriction = NULL;
 104                 goto out;
 105         }
 106
 107         if (!IS_ENABLED(CONFIG_INTEGRITY_TRUSTED_KEYRING))
 108                 return 0;
 109
 110         restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
 111         if (!restriction)
 112                 return -ENOMEM;
 113
 114         restriction->check = restrict_link_to_ima;
 115         perm |= KEY_USR_WRITE;
 116
 117 out:
 118         return __integrity_init_keyring(id, perm, restriction);
 119 }
 120
 121 int __init integrity_add_key(const unsigned int id, const void *data,
 122                              off_t size, key_perm_t perm)
 123 {
 124         key_ref_t key;
 125         int rc = 0;
 126
 127         if (!keyring[id])
 128                 return -EINVAL;
 129
 130         key = key_create_or_update(make_key_ref(keyring[id], 1), "asymmetric",
 131                                    NULL, data, size, perm,
 132                                    KEY_ALLOC_NOT_IN_QUOTA);
 133         if (IS_ERR(key)) {
 134                 rc = PTR_ERR(key);
 135                 pr_err("Problem loading X.509 certificate %d\n", rc);
 136         } else {
 137                 pr_notice("Loaded X.509 cert '%s'\n",
 138                           key_ref_to_ptr(key)->description);
 139                 key_ref_put(key);
 140         }
 141
 142         return rc;
 143
 144 }
 145
 146 int __init integrity_load_x509(const unsigned int id, const char *path)
 147 {
 148         void *data;
 149         loff_t size;
 150         int rc;
 151         key_perm_t perm;
 152
 153         rc = kernel_read_file_from_path(path, &data, &size, 0,
 154                                         READING_X509_CERTIFICATE);
 155         if (rc < 0) {
 156                 pr_err("Unable to open file: %s (%d)", path, rc);
 157                 return rc;
 158         }
 159
 160         perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW | KEY_USR_READ;
 161
 162         pr_info("Loading X.509 certificate: %s\n", path);
 163         rc = integrity_add_key(id, (const void *)data, size, perm);
 164
 165         vfree(data);
 166         return rc;
 167 }
 168
 169 int __init integrity_load_cert(const unsigned int id, const char *source,
 170                                const void *data, size_t len, key_perm_t perm)
 171 {
 172         if (!data)
 173                 return -EINVAL;
 174
 175         pr_info("Loading X.509 certificate: %s\n", source);
 176         return integrity_add_key(id, data, len, perm);
 177 }