/* 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 <linux/slab.h>
#include <keys/asymmetric-type.h>
#include <keys/system_keyring.h>
#include <crypto/pkcs7.h>
static struct key *builtin_trusted_keys;
#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
static struct key *secondary_trusted_keys;
#endif
extern __initconst const u8 system_certificate_list[];
extern __initconst const unsigned long system_certificate_list_size;
/**
* restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA
*
* Restrict the addition of keys into a keyring based on the key-to-be-added
* being vouched for by a key in the built in system keyring.
*/
int restrict_link_by_builtin_trusted(struct key *dest_keyring,
const struct key_type *type,
const union key_payload *payload,
struct key *restriction_key)
{
return restrict_link_by_signature(dest_keyring, type, payload,
builtin_trusted_keys);
}
#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
/**
* restrict_link_by_builtin_and_secondary_trusted - Restrict keyring
* addition by both builtin and secondary keyrings
*
* Restrict the addition of keys into a keyring based on the key-to-be-added
* being vouched for by a key in either the built-in or the secondary system
* keyrings.
*/
int restrict_link_by_builtin_and_secondary_trusted(
struct key *dest_keyring,
const struct key_type *type,
const union key_payload *payload,
struct key *restrict_key)
{
/* If we have a secondary trusted keyring, then that contains a link
* through to the builtin keyring and the search will follow that link.
*/
if (type == &key_type_keyring &&
dest_keyring == secondary_trusted_keys &&
payload == &builtin_trusted_keys->payload)
/* Allow the builtin keyring to be added to the secondary */
return 0;
return restrict_link_by_signature(dest_keyring, type, payload,
secondary_trusted_keys);
}
/**
* Allocate a struct key_restriction for the "builtin and secondary trust"
* keyring. Only for use in system_trusted_keyring_init().
*/
static __init struct key_restriction *get_builtin_and_secondary_restriction(void)
{
struct key_restriction *restriction;
restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
if (!restriction)
panic("Can't allocate secondary trusted keyring restriction\n");
restriction->check = restrict_link_by_builtin_and_secondary_trusted;
return restriction;
}
#endif
/*
* Create the trusted keyrings
*/
static __init int system_trusted_keyring_init(void)
{
pr_notice("Initialise system trusted keyrings\n");
builtin_trusted_keys =
keyring_alloc(".builtin_trusted_keys",
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, NULL);
if (IS_ERR(builtin_trusted_keys))
panic("Can't allocate builtin trusted keyring\n");
#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
secondary_trusted_keys =
keyring_alloc(".secondary_trusted_keys",
KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
((KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH |
KEY_USR_WRITE),
KEY_ALLOC_NOT_IN_QUOTA,
get_builtin_and_secondary_restriction(),
NULL);
if (IS_ERR(secondary_trusted_keys))
panic("Can't allocate secondary trusted keyring\n");
if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0)
panic("Can't link trusted keyrings\n");
#endif
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(builtin_trusted_keys, 1),
"asymmetric",
NULL,
p,
plen,
((KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ),
KEY_ALLOC_NOT_IN_QUOTA |
KEY_ALLOC_BUILT_IN |
KEY_ALLOC_BYPASS_RESTRICTION);
if (IS_ERR(key)) {
pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
PTR_ERR(key));
} else {
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_pkcs7_signature - Verify a PKCS#7-based signature on system data.
* @data: The data to be verified (NULL if expecting internal data).
* @len: Size of @data.
* @raw_pkcs7: The PKCS#7 message that is the signature.
* @pkcs7_len: The size of @raw_pkcs7.
* @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,
* (void *)1UL for all trusted keys).
* @usage: The use to which the key is being put.
* @view_content: Callback to gain access to content.
* @ctx: Context for callback.
*/
int verify_pkcs7_signature(const void *data, size_t len,
const void *raw_pkcs7, size_t pkcs7_len,
struct key *trusted_keys,
enum key_being_used_for usage,
int (*view_content)(void *ctx,
const void *data, size_t len,
size_t asn1hdrlen),
void *ctx)
{
struct pkcs7_message *pkcs7;
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 (data && 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;
if (!trusted_keys) {
trusted_keys = builtin_trusted_keys;
} else if (trusted_keys == (void *)1UL) {
#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
trusted_keys = secondary_trusted_keys;
#else
trusted_keys = builtin_trusted_keys;
#endif
}
ret = pkcs7_validate_trust(pkcs7, trusted_keys);
if (ret < 0) {
if (ret == -ENOKEY)
pr_err("PKCS#7 signature not signed with a trusted key\n");
goto error;
}
if (view_content) {
size_t asn1hdrlen;
ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen);
if (ret < 0) {
if (ret == -ENODATA)
pr_devel("PKCS#7 message does not contain data\n");
goto error;
}
ret = view_content(ctx, data, len, asn1hdrlen);
}
error:
pkcs7_free_message(pkcs7);
pr_devel("<==%s() = %d\n", __func__, ret);
return ret;
}
EXPORT_SYMBOL_GPL(verify_pkcs7_signature);
#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
