system_keyring.c
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/* System trusted keyring for trusted public keys
*
* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/cred.h>
#include <linux/err.h>
#include <keys/asymmetric-type.h>
#include <keys/system_keyring.h>
#include <crypto/pkcs7.h>
struct key *system_trusted_keyring;
EXPORT_SYMBOL_GPL(system_trusted_keyring);
extern __initconst const u8 system_certificate_list[];
extern __initconst const unsigned long system_certificate_list_size;
/*
* Load the compiled-in keys
*/
static __init int system_trusted_keyring_init(void)
{
pr_notice("Initialise system trusted keyring\n");
system_trusted_keyring =
keyring_alloc(".system_keyring",
KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
((KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH),
KEY_ALLOC_NOT_IN_QUOTA, NULL);
if (IS_ERR(system_trusted_keyring))
panic("Can't allocate system trusted keyring\n");
set_bit(KEY_FLAG_TRUSTED_ONLY, &system_trusted_keyring->flags);
return 0;
}
/*
* Must be initialised before we try and load the keys into the keyring.
*/
device_initcall(system_trusted_keyring_init);
/*
* Load the compiled-in list of X.509 certificates.
*/
static __init int load_system_certificate_list(void)
{
key_ref_t key;
const u8 *p, *end;
size_t plen;
pr_notice("Loading compiled-in X.509 certificates\n");
p = system_certificate_list;
end = p + system_certificate_list_size;
while (p < end) {
/* Each cert begins with an ASN.1 SEQUENCE tag and must be more
* than 256 bytes in size.
*/
if (end - p < 4)
goto dodgy_cert;
if (p[0] != 0x30 &&
p[1] != 0x82)
goto dodgy_cert;
plen = (p[2] << 8) | p[3];
plen += 4;
if (plen > end - p)
goto dodgy_cert;
key = key_create_or_update(make_key_ref(system_trusted_keyring, 1),
"asymmetric",
NULL,
p,
plen,
((KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ),
KEY_ALLOC_NOT_IN_QUOTA |
KEY_ALLOC_TRUSTED);
if (IS_ERR(key)) {
pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
PTR_ERR(key));
} else {
set_bit(KEY_FLAG_BUILTIN, &key_ref_to_ptr(key)->flags);
pr_notice("Loaded X.509 cert '%s'\n",
key_ref_to_ptr(key)->description);
key_ref_put(key);
}
p += plen;
}
return 0;
dodgy_cert:
pr_err("Problem parsing in-kernel X.509 certificate list\n");
return 0;
}
late_initcall(load_system_certificate_list);
#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
/**
* Verify a PKCS#7-based signature on system data.
* @data: The data to be verified.
* @len: Size of @data.
* @raw_pkcs7: The PKCS#7 message that is the signature.
* @pkcs7_len: The size of @raw_pkcs7.
* @usage: The use to which the key is being put.
*/
int system_verify_data(const void *data, unsigned long len,
const void *raw_pkcs7, size_t pkcs7_len,
enum key_being_used_for usage)
{
struct pkcs7_message *pkcs7;
bool trusted;
int ret;
pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);
if (IS_ERR(pkcs7))
return PTR_ERR(pkcs7);
/* The data should be detached - so we need to supply it. */
if (pkcs7_supply_detached_data(pkcs7, data, len) < 0) {
pr_err("PKCS#7 signature with non-detached data\n");
ret = -EBADMSG;
goto error;
}
ret = pkcs7_verify(pkcs7, usage);
if (ret < 0)
goto error;
ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted);
if (ret < 0)
goto error;
if (!trusted) {
pr_err("PKCS#7 signature not signed with a trusted key\n");
ret = -ENOKEY;
}
error:
pkcs7_free_message(pkcs7);
pr_devel("<==%s() = %d\n", __func__, ret);
return ret;
}
EXPORT_SYMBOL_GPL(system_verify_data);
#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */