// SPDX-License-Identifier: GPL-2.0-or-later
/* Asymmetric public-key cryptography key type
*
* See Documentation/crypto/asymmetric-keys.rst
*
* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
* Written by David Howells ([email protected])
*/
#include <keys/asymmetric-subtype.h>
#include <keys/asymmetric-parser.h>
#include <crypto/public_key.h>
#include <linux/seq_file.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/ctype.h>
#include <keys/system_keyring.h>
#include <keys/user-type.h>
#include "asymmetric_keys.h"
const char *const key_being_used_for[NR__KEY_BEING_USED_FOR] = {
[VERIFYING_MODULE_SIGNATURE] = "mod sig",
[VERIFYING_FIRMWARE_SIGNATURE] = "firmware sig",
[VERIFYING_KEXEC_PE_SIGNATURE] = "kexec PE sig",
[VERIFYING_KEY_SIGNATURE] = "key sig",
[VERIFYING_KEY_SELF_SIGNATURE] = "key self sig",
[VERIFYING_UNSPECIFIED_SIGNATURE] = "unspec sig",
};
EXPORT_SYMBOL_GPL(key_being_used_for);
static LIST_HEAD(asymmetric_key_parsers);
static DECLARE_RWSEM(asymmetric_key_parsers_sem);
/**
* find_asymmetric_key - Find a key by ID.
* @keyring: The keys to search.
* @id_0: The first ID to look for or NULL.
* @id_1: The second ID to look for or NULL, matched together with @id_0
* against @keyring keys' id[0] and id[1].
* @id_2: The fallback ID to match against @keyring keys' id[2] if both of the
* other IDs are NULL.
* @partial: Use partial match for @id_0 and @id_1 if true, exact if false.
*
* Find a key in the given keyring by identifier. The preferred identifier is
* the id_0 and the fallback identifier is the id_1. If both are given, the
* former is matched (exactly or partially) against either of the sought key's
* identifiers and the latter must match the found key's second identifier
* exactly. If both are missing, id_2 must match the sought key's third
* identifier exactly.
*/
struct key *find_asymmetric_key(struct key *keyring,
const struct asymmetric_key_id *id_0,
const struct asymmetric_key_id *id_1,
const struct asymmetric_key_id *id_2,
bool partial)
{
struct key *key;
key_ref_t ref;
const char *lookup;
char *req, *p;
int len;
if (id_0) {
lookup = id_0->data;
len = id_0->len;
} else if (id_1) {
lookup = id_1->data;
len = id_1->len;
} else if (id_2) {
lookup = id_2->data;
len = id_2->len;
} else {
WARN_ON(1);
return ERR_PTR(-EINVAL);
}
/* Construct an identifier "id:<keyid>". */
p = req = kmalloc(2 + 1 + len * 2 + 1, GFP_KERNEL);
if (!req)
return ERR_PTR(-ENOMEM);
if (!id_0 && !id_1) {
*p++ = 'd';
*p++ = 'n';
} else if (partial) {
*p++ = 'i';
*p++ = 'd';
} else {
*p++ = 'e';
*p++ = 'x';
}
*p++ = ':';
p = bin2hex(p, lookup, len);
*p = 0;
pr_debug("Look up: \"%s\"\n", req);
ref = keyring_search(make_key_ref(keyring, 1),
&key_type_asymmetric, req, true);
if (IS_ERR(ref))
pr_debug("Request for key '%s' err %ld\n", req, PTR_ERR(ref));
kfree(req);
if (IS_ERR(ref)) {
switch (PTR_ERR(ref)) {
/* Hide some search errors */
case -EACCES:
case -ENOTDIR:
case -EAGAIN:
return ERR_PTR(-ENOKEY);
default:
return ERR_CAST(ref);
}
}
key = key_ref_to_ptr(ref);
if (id_0 && id_1) {
const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
if (!kids->id[1]) {
pr_debug("First ID matches, but second is missing\n");
goto reject;
}
if (!asymmetric_key_id_same(id_1, kids->id[1])) {
pr_debug("First ID matches, but second does not\n");
goto reject;
}
}
pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key));
return key;
reject:
key_put(key);
return ERR_PTR(-EKEYREJECTED);
}
EXPORT_SYMBOL_GPL(find_asymmetric_key);
/**
* asymmetric_key_generate_id: Construct an asymmetric key ID
* @val_1: First binary blob
* @len_1: Length of first binary blob
* @val_2: Second binary blob
* @len_2: Length of second binary blob
*
* Construct an asymmetric key ID from a pair of binary blobs.
*/
struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
size_t len_1,
const void *val_2,
size_t len_2)
{
struct asymmetric_key_id *kid;
kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
GFP_KERNEL);
if (!kid)
return ERR_PTR(-ENOMEM);
kid->len = len_1 + len_2;
memcpy(kid->data, val_1, len_1);
memcpy(kid->data + len_1, val_2, len_2);
return kid;
}
EXPORT_SYMBOL_GPL(asymmetric_key_generate_id);
/**
* asymmetric_key_id_same - Return true if two asymmetric keys IDs are the same.
* @kid1: The key ID to compare
* @kid2: The key ID to compare
*/
bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
const struct asymmetric_key_id *kid2)
{
if (!kid1 || !kid2)
return false;
if (kid1->len != kid2->len)
return false;
return memcmp(kid1->data, kid2->data, kid1->len) == 0;
}
EXPORT_SYMBOL_GPL(asymmetric_key_id_same);
/**
* asymmetric_key_id_partial - Return true if two asymmetric keys IDs
* partially match
* @kid1: The key ID to compare
* @kid2: The key ID to compare
*/
bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
const struct asymmetric_key_id *kid2)
{
if (!kid1 || !kid2)
return false;
if (kid1->len < kid2->len)
return false;
return memcmp(kid1->data + (kid1->len - kid2->len),
kid2->data, kid2->len) == 0;
}
EXPORT_SYMBOL_GPL(asymmetric_key_id_partial);
/**
* asymmetric_match_key_ids - Search asymmetric key IDs 1 & 2
* @kids: The pair of key IDs to check
* @match_id: The key ID we're looking for
* @match: The match function to use
*/
static bool asymmetric_match_key_ids(
const struct asymmetric_key_ids *kids,
const struct asymmetric_key_id *match_id,
bool (*match)(const struct asymmetric_key_id *kid1,
const struct asymmetric_key_id *kid2))
{
int i;
if (!kids || !match_id)
return false;
for (i = 0; i < 2; i++)
if (match(kids->id[i], match_id))
return true;
return false;
}
/* helper function can be called directly with pre-allocated memory */
inline int __asymmetric_key_hex_to_key_id(const char *id,
struct asymmetric_key_id *match_id,
size_t hexlen)
{
match_id->len = hexlen;
return hex2bin(match_id->data, id, hexlen);
}
/**
* asymmetric_key_hex_to_key_id - Convert a hex string into a key ID.
* @id: The ID as a hex string.
*/
struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id)
{
struct asymmetric_key_id *match_id;
size_t asciihexlen;
int ret;
if (!*id)
return ERR_PTR(-EINVAL);
asciihexlen = strlen(id);
if (asciihexlen & 1)
return ERR_PTR(-EINVAL);
match_id = kmalloc(sizeof(struct asymmetric_key_id) + asciihexlen / 2,
GFP_KERNEL);
if (!match_id)
return ERR_PTR(-ENOMEM);
ret = __asymmetric_key_hex_to_key_id(id, match_id, asciihexlen / 2);
if (ret < 0) {
kfree(match_id);
return ERR_PTR(-EINVAL);
}
return match_id;
}
/*
* Match asymmetric keys by an exact match on one of the first two IDs.
*/
static bool asymmetric_key_cmp(const struct key *key,
const struct key_match_data *match_data)
{
const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
const struct asymmetric_key_id *match_id = match_data->preparsed;
return asymmetric_match_key_ids(kids, match_id,
asymmetric_key_id_same);
}
/*
* Match asymmetric keys by a partial match on one of the first two IDs.
*/
static bool asymmetric_key_cmp_partial(const struct key *key,
const struct key_match_data *match_data)
{
const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
const struct asymmetric_key_id *match_id = match_data->preparsed;
return asymmetric_match_key_ids(kids, match_id,
asymmetric_key_id_partial);
}
/*
* Match asymmetric keys by an exact match on the third IDs.
*/
static bool asymmetric_key_cmp_name(const struct key *key,
const struct key_match_data *match_data)
{
const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
const struct asymmetric_key_id *match_id = match_data->preparsed;
return kids && asymmetric_key_id_same(kids->id[2], match_id);
}
/*
* Preparse the match criterion. If we don't set lookup_type and cmp,
* the default will be an exact match on the key description.
*
* There are some specifiers for matching key IDs rather than by the key
* description:
*
* "id:<id>" - find a key by partial match on one of the first two IDs
* "ex:<id>" - find a key by exact match on one of the first two IDs
* "dn:<id>" - find a key by exact match on the third ID
*
* These have to be searched by iteration rather than by direct lookup because
* the key is hashed according to its description.
*/
static int asymmetric_key_match_preparse(struct key_match_data *match_data)
{
struct asymmetric_key_id *match_id;
const char *spec = match_data->raw_data;
const char *id;
bool (*cmp)(const struct key *, const struct key_match_data *) =
asymmetric_key_cmp;
if (!spec || !*spec)
return -EINVAL;
if (spec[0] == 'i' &&
spec[1] == 'd' &&
spec[2] == ':') {
id = spec + 3;
cmp = asymmetric_key_cmp_partial;
} else if (spec[0] == 'e' &&
spec[1] == 'x' &&
spec[2] == ':') {
id = spec + 3;
} else if (spec[0] == 'd' &&
spec[1] == 'n' &&
spec[2] == ':') {
id = spec + 3;
cmp = asymmetric_key_cmp_name;
} else {
goto default_match;
}
match_id = asymmetric_key_hex_to_key_id(id);
if (IS_ERR(match_id))
return PTR_ERR(match_id);
match_data->preparsed = match_id;
match_data->cmp = cmp;
match_data->lookup_type = KEYRING_SEARCH_LOOKUP_ITERATE;
return 0;
default_match:
return 0;
}
/*
* Free the preparsed the match criterion.
*/
static void asymmetric_key_match_free(struct key_match_data *match_data)
{
kfree(match_data->preparsed);
}
/*
* Describe the asymmetric key
*/
static void asymmetric_key_describe(const struct key *key, struct seq_file *m)
{
const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
const struct asymmetric_key_id *kid;
const unsigned char *p;
int n;
seq_puts(m, key->description);
if (subtype) {
seq_puts(m, ": ");
subtype->describe(key, m);
if (kids && kids->id[1]) {
kid = kids->id[1];
seq_putc(m, ' ');
n = kid->len;
p = kid->data;
if (n > 4) {
p += n - 4;
n = 4;
}
seq_printf(m, "%*phN", n, p);
}
seq_puts(m, " [");
/* put something here to indicate the key's capabilities */
seq_putc(m, ']');
}
}
/*
* Preparse a asymmetric payload to get format the contents appropriately for the
* internal payload to cut down on the number of scans of the data performed.
*
* We also generate a proposed description from the contents of the key that
* can be used to name the key if the user doesn't want to provide one.
*/
static int asymmetric_key_preparse(struct key_preparsed_payload *prep)
{
struct asymmetric_key_parser *parser;
int ret;
pr_devel("==>%s()\n", __func__);
if (prep->datalen == 0)
return -EINVAL;
down_read(&asymmetric_key_parsers_sem);
ret = -EBADMSG;
list_for_each_entry(parser, &asymmetric_key_parsers, link) {
pr_debug("Trying parser '%s'\n", parser->name);
ret = parser->parse(prep);
if (ret != -EBADMSG) {
pr_debug("Parser recognised the format (ret %d)\n",
ret);
break;
}
}
up_read(&asymmetric_key_parsers_sem);
pr_devel("<==%s() = %d\n", __func__, ret);
return ret;
}
/*
* Clean up the key ID list
*/
static void asymmetric_key_free_kids(struct asymmetric_key_ids *kids)
{
int i;
if (kids) {
for (i = 0; i < ARRAY_SIZE(kids->id); i++)
kfree(kids->id[i]);
kfree(kids);
}
}
/*
* Clean up the preparse data
*/
static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep)
{
struct asymmetric_key_subtype *subtype = prep->payload.data[asym_subtype];
struct asymmetric_key_ids *kids = prep->payload.data[asym_key_ids];
pr_devel("==>%s()\n", __func__);
if (subtype) {
subtype->destroy(prep->payload.data[asym_crypto],
prep->payload.data[asym_auth]);
module_put(subtype->owner);
}
asymmetric_key_free_kids(kids);
kfree(prep->description);
}
/*
* dispose of the data dangling from the corpse of a asymmetric key
*/
static void asymmetric_key_destroy(struct key *key)
{
struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
struct asymmetric_key_ids *kids = key->payload.data[asym_key_ids];
void *data = key->payload.data[asym_crypto];
void *auth = key->payload.data[asym_auth];
key->payload.data[asym_crypto] = NULL;
key->payload.data[asym_subtype] = NULL;
key->payload.data[asym_key_ids] = NULL;
key->payload.data[asym_auth] = NULL;
if (subtype) {
subtype->destroy(data, auth);
module_put(subtype->owner);
}
asymmetric_key_free_kids(kids);
}
static struct key_restriction *asymmetric_restriction_alloc(
key_restrict_link_func_t check,
struct key *key)
{
struct key_restriction *keyres =
kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
if (!keyres)
return ERR_PTR(-ENOMEM);
keyres->check = check;
keyres->key = key;
keyres->keytype = &key_type_asymmetric;
return keyres;
}
/*
* look up keyring restrict functions for asymmetric keys
*/
static struct key_restriction *asymmetric_lookup_restriction(
const char *restriction)
{
char *restrict_method;
char *parse_buf;
char *next;
struct key_restriction *ret = ERR_PTR(-EINVAL);
if (strcmp("builtin_trusted", restriction) == 0)
return asymmetric_restriction_alloc(
restrict_link_by_builtin_trusted, NULL);
if (strcmp("builtin_and_secondary_trusted", restriction) == 0)
return asymmetric_restriction_alloc(
restrict_link_by_builtin_and_secondary_trusted, NULL);
parse_buf = kstrndup(restriction, PAGE_SIZE, GFP_KERNEL);
if (!parse_buf)
return ERR_PTR(-ENOMEM);
next = parse_buf;
restrict_method = strsep(&next, ":");
if ((strcmp(restrict_method, "key_or_keyring") == 0) && next) {
char *key_text;
key_serial_t serial;
struct key *key;
key_restrict_link_func_t link_fn =
restrict_link_by_key_or_keyring;
bool allow_null_key = false;
key_text = strsep(&next, ":");
if (next) {
if (strcmp(next, "chain") != 0)
goto out;
link_fn = restrict_link_by_key_or_keyring_chain;
allow_null_key = true;
}
if (kstrtos32(key_text, 0, &serial) < 0)
goto out;
if ((serial == 0) && allow_null_key) {
key = NULL;
} else {
key = key_lookup(serial);
if (IS_ERR(key)) {
ret = ERR_CAST(key);
goto out;
}
}
ret = asymmetric_restriction_alloc(link_fn, key);
if (IS_ERR(ret))
key_put(key);
}
out:
kfree(parse_buf);
return ret;
}
int asymmetric_key_eds_op(struct kernel_pkey_params *params,
const void *in, void *out)
{
const struct asymmetric_key_subtype *subtype;
struct key *key = params->key;
int ret;
pr_devel("==>%s()\n", __func__);
if (key->type != &key_type_asymmetric)
return -EINVAL;
subtype = asymmetric_key_subtype(key);
if (!subtype ||
!key->payload.data[0])
return -EINVAL;
if (!subtype->eds_op)
return -ENOTSUPP;
ret = subtype->eds_op(params, in, out);
pr_devel("<==%s() = %d\n", __func__, ret);
return ret;
}
static int asymmetric_key_verify_signature(struct kernel_pkey_params *params,
const void *in, const void *in2)
{
struct public_key_signature sig = {
.s_size = params->in2_len,
.digest_size = params->in_len,
.encoding = params->encoding,
.hash_algo = params->hash_algo,
.digest = (void *)in,
.s = (void *)in2,
};
return verify_signature(params->key, &sig);
}
struct key_type key_type_asymmetric = {
.name = "asymmetric",
.preparse = asymmetric_key_preparse,
.free_preparse = asymmetric_key_free_preparse,
.instantiate = generic_key_instantiate,
.match_preparse = asymmetric_key_match_preparse,
.match_free = asymmetric_key_match_free,
.destroy = asymmetric_key_destroy,
.describe = asymmetric_key_describe,
.lookup_restriction = asymmetric_lookup_restriction,
.asym_query = query_asymmetric_key,
.asym_eds_op = asymmetric_key_eds_op,
.asym_verify_signature = asymmetric_key_verify_signature,
};
EXPORT_SYMBOL_GPL(key_type_asymmetric);
/**
* register_asymmetric_key_parser - Register a asymmetric key blob parser
* @parser: The parser to register
*/
int register_asymmetric_key_parser(struct asymmetric_key_parser *parser)
{
struct asymmetric_key_parser *cursor;
int ret;
down_write(&asymmetric_key_parsers_sem);
list_for_each_entry(cursor, &asymmetric_key_parsers, link) {
if (strcmp(cursor->name, parser->name) == 0) {
pr_err("Asymmetric key parser '%s' already registered\n",
parser->name);
ret = -EEXIST;
goto out;
}
}
list_add_tail(&parser->link, &asymmetric_key_parsers);
pr_notice("Asymmetric key parser '%s' registered\n", parser->name);
ret = 0;
out:
up_write(&asymmetric_key_parsers_sem);
return ret;
}
EXPORT_SYMBOL_GPL(register_asymmetric_key_parser);
/**
* unregister_asymmetric_key_parser - Unregister a asymmetric key blob parser
* @parser: The parser to unregister
*/
void unregister_asymmetric_key_parser(struct asymmetric_key_parser *parser)
{
down_write(&asymmetric_key_parsers_sem);
list_del(&parser->link);
up_write(&asymmetric_key_parsers_sem);
pr_notice("Asymmetric key parser '%s' unregistered\n", parser->name);
}
EXPORT_SYMBOL_GPL(unregister_asymmetric_key_parser);
/*
* Module stuff
*/
static int __init asymmetric_key_init(void)
{
return register_key_type(&key_type_asymmetric);
}
static void __exit asymmetric_key_cleanup(void)
{
unregister_key_type(&key_type_asymmetric);
}
module_init(asymmetric_key_init);
module_exit(asymmetric_key_cleanup);
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