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![David Howells](/assets/img/avatar_default.png)
Generalise x509_request_asymmetric_key(). It doesn't really have any dependencies on X.509 features as it uses generalised IDs and the public_key structs that contain data extracted from X.509. Signed-off-by: David Howells <dhowells@redhat.com>
525 lines
13 KiB
C
525 lines
13 KiB
C
/* Asymmetric public-key cryptography key type
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*
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* See Documentation/security/asymmetric-keys.txt
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*
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* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#include <keys/asymmetric-subtype.h>
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#include <keys/asymmetric-parser.h>
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#include <crypto/public_key.h>
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#include <linux/seq_file.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/ctype.h>
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#include "asymmetric_keys.h"
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MODULE_LICENSE("GPL");
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const char *const key_being_used_for[NR__KEY_BEING_USED_FOR] = {
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[VERIFYING_MODULE_SIGNATURE] = "mod sig",
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[VERIFYING_FIRMWARE_SIGNATURE] = "firmware sig",
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[VERIFYING_KEXEC_PE_SIGNATURE] = "kexec PE sig",
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[VERIFYING_KEY_SIGNATURE] = "key sig",
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[VERIFYING_KEY_SELF_SIGNATURE] = "key self sig",
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[VERIFYING_UNSPECIFIED_SIGNATURE] = "unspec sig",
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};
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EXPORT_SYMBOL_GPL(key_being_used_for);
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static LIST_HEAD(asymmetric_key_parsers);
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static DECLARE_RWSEM(asymmetric_key_parsers_sem);
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/**
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* find_asymmetric_key - Find a key by ID.
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* @keyring: The keys to search.
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* @id_0: The first ID to look for or NULL.
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* @id_1: The second ID to look for or NULL.
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* @partial: Use partial match if true, exact if false.
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*
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* Find a key in the given keyring by identifier. The preferred identifier is
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* the id_0 and the fallback identifier is the id_1. If both are given, the
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* lookup is by the former, but the latter must also match.
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*/
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struct key *find_asymmetric_key(struct key *keyring,
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const struct asymmetric_key_id *id_0,
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const struct asymmetric_key_id *id_1,
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bool partial)
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{
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struct key *key;
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key_ref_t ref;
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const char *lookup;
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char *req, *p;
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int len;
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if (id_0) {
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lookup = id_0->data;
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len = id_0->len;
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} else {
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lookup = id_1->data;
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len = id_1->len;
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}
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/* Construct an identifier "id:<keyid>". */
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p = req = kmalloc(2 + 1 + len * 2 + 1, GFP_KERNEL);
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if (!req)
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return ERR_PTR(-ENOMEM);
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if (partial) {
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*p++ = 'i';
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*p++ = 'd';
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} else {
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*p++ = 'e';
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*p++ = 'x';
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}
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*p++ = ':';
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p = bin2hex(p, lookup, len);
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*p = 0;
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pr_debug("Look up: \"%s\"\n", req);
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ref = keyring_search(make_key_ref(keyring, 1),
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&key_type_asymmetric, req);
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if (IS_ERR(ref))
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pr_debug("Request for key '%s' err %ld\n", req, PTR_ERR(ref));
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kfree(req);
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if (IS_ERR(ref)) {
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switch (PTR_ERR(ref)) {
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/* Hide some search errors */
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case -EACCES:
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case -ENOTDIR:
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case -EAGAIN:
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return ERR_PTR(-ENOKEY);
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default:
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return ERR_CAST(ref);
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}
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}
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key = key_ref_to_ptr(ref);
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if (id_0 && id_1) {
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const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
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if (!kids->id[0]) {
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pr_debug("First ID matches, but second is missing\n");
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goto reject;
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}
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if (!asymmetric_key_id_same(id_1, kids->id[1])) {
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pr_debug("First ID matches, but second does not\n");
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goto reject;
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}
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}
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pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key));
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return key;
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reject:
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key_put(key);
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return ERR_PTR(-EKEYREJECTED);
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}
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EXPORT_SYMBOL_GPL(find_asymmetric_key);
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/**
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* asymmetric_key_generate_id: Construct an asymmetric key ID
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* @val_1: First binary blob
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* @len_1: Length of first binary blob
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* @val_2: Second binary blob
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* @len_2: Length of second binary blob
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*
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* Construct an asymmetric key ID from a pair of binary blobs.
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*/
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struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
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size_t len_1,
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const void *val_2,
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size_t len_2)
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{
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struct asymmetric_key_id *kid;
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kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
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GFP_KERNEL);
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if (!kid)
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return ERR_PTR(-ENOMEM);
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kid->len = len_1 + len_2;
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memcpy(kid->data, val_1, len_1);
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memcpy(kid->data + len_1, val_2, len_2);
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return kid;
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}
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EXPORT_SYMBOL_GPL(asymmetric_key_generate_id);
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/**
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* asymmetric_key_id_same - Return true if two asymmetric keys IDs are the same.
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* @kid_1, @kid_2: The key IDs to compare
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*/
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bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
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const struct asymmetric_key_id *kid2)
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{
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if (!kid1 || !kid2)
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return false;
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if (kid1->len != kid2->len)
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return false;
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return memcmp(kid1->data, kid2->data, kid1->len) == 0;
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}
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EXPORT_SYMBOL_GPL(asymmetric_key_id_same);
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/**
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* asymmetric_key_id_partial - Return true if two asymmetric keys IDs
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* partially match
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* @kid_1, @kid_2: The key IDs to compare
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*/
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bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
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const struct asymmetric_key_id *kid2)
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{
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if (!kid1 || !kid2)
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return false;
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if (kid1->len < kid2->len)
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return false;
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return memcmp(kid1->data + (kid1->len - kid2->len),
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kid2->data, kid2->len) == 0;
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}
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EXPORT_SYMBOL_GPL(asymmetric_key_id_partial);
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/**
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* asymmetric_match_key_ids - Search asymmetric key IDs
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* @kids: The list of key IDs to check
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* @match_id: The key ID we're looking for
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* @match: The match function to use
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*/
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static bool asymmetric_match_key_ids(
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const struct asymmetric_key_ids *kids,
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const struct asymmetric_key_id *match_id,
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bool (*match)(const struct asymmetric_key_id *kid1,
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const struct asymmetric_key_id *kid2))
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{
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int i;
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if (!kids || !match_id)
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return false;
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for (i = 0; i < ARRAY_SIZE(kids->id); i++)
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if (match(kids->id[i], match_id))
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return true;
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return false;
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}
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/* helper function can be called directly with pre-allocated memory */
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inline int __asymmetric_key_hex_to_key_id(const char *id,
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struct asymmetric_key_id *match_id,
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size_t hexlen)
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{
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match_id->len = hexlen;
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return hex2bin(match_id->data, id, hexlen);
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}
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/**
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* asymmetric_key_hex_to_key_id - Convert a hex string into a key ID.
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* @id: The ID as a hex string.
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*/
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struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id)
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{
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struct asymmetric_key_id *match_id;
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size_t asciihexlen;
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int ret;
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if (!*id)
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return ERR_PTR(-EINVAL);
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asciihexlen = strlen(id);
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if (asciihexlen & 1)
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return ERR_PTR(-EINVAL);
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match_id = kmalloc(sizeof(struct asymmetric_key_id) + asciihexlen / 2,
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GFP_KERNEL);
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if (!match_id)
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return ERR_PTR(-ENOMEM);
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ret = __asymmetric_key_hex_to_key_id(id, match_id, asciihexlen / 2);
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if (ret < 0) {
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kfree(match_id);
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return ERR_PTR(-EINVAL);
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}
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return match_id;
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}
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/*
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* Match asymmetric keys by an exact match on an ID.
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*/
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static bool asymmetric_key_cmp(const struct key *key,
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const struct key_match_data *match_data)
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{
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const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
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const struct asymmetric_key_id *match_id = match_data->preparsed;
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return asymmetric_match_key_ids(kids, match_id,
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asymmetric_key_id_same);
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}
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/*
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* Match asymmetric keys by a partial match on an IDs.
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*/
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static bool asymmetric_key_cmp_partial(const struct key *key,
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const struct key_match_data *match_data)
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{
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const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
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const struct asymmetric_key_id *match_id = match_data->preparsed;
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return asymmetric_match_key_ids(kids, match_id,
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asymmetric_key_id_partial);
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}
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/*
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* Preparse the match criterion. If we don't set lookup_type and cmp,
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* the default will be an exact match on the key description.
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*
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* There are some specifiers for matching key IDs rather than by the key
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* description:
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*
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* "id:<id>" - find a key by partial match on any available ID
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* "ex:<id>" - find a key by exact match on any available ID
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*
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* These have to be searched by iteration rather than by direct lookup because
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* the key is hashed according to its description.
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*/
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static int asymmetric_key_match_preparse(struct key_match_data *match_data)
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{
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struct asymmetric_key_id *match_id;
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const char *spec = match_data->raw_data;
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const char *id;
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bool (*cmp)(const struct key *, const struct key_match_data *) =
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asymmetric_key_cmp;
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if (!spec || !*spec)
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return -EINVAL;
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if (spec[0] == 'i' &&
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spec[1] == 'd' &&
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spec[2] == ':') {
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id = spec + 3;
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cmp = asymmetric_key_cmp_partial;
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} else if (spec[0] == 'e' &&
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spec[1] == 'x' &&
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spec[2] == ':') {
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id = spec + 3;
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} else {
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goto default_match;
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}
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match_id = asymmetric_key_hex_to_key_id(id);
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if (IS_ERR(match_id))
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return PTR_ERR(match_id);
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match_data->preparsed = match_id;
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match_data->cmp = cmp;
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match_data->lookup_type = KEYRING_SEARCH_LOOKUP_ITERATE;
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return 0;
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default_match:
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return 0;
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}
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/*
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* Free the preparsed the match criterion.
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*/
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static void asymmetric_key_match_free(struct key_match_data *match_data)
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{
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kfree(match_data->preparsed);
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}
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/*
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* Describe the asymmetric key
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*/
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static void asymmetric_key_describe(const struct key *key, struct seq_file *m)
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{
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const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
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const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
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const struct asymmetric_key_id *kid;
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const unsigned char *p;
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int n;
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seq_puts(m, key->description);
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if (subtype) {
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seq_puts(m, ": ");
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subtype->describe(key, m);
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if (kids && kids->id[1]) {
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kid = kids->id[1];
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seq_putc(m, ' ');
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n = kid->len;
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p = kid->data;
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if (n > 4) {
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p += n - 4;
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n = 4;
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}
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seq_printf(m, "%*phN", n, p);
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}
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seq_puts(m, " [");
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/* put something here to indicate the key's capabilities */
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seq_putc(m, ']');
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}
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}
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/*
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* Preparse a asymmetric payload to get format the contents appropriately for the
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* internal payload to cut down on the number of scans of the data performed.
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*
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* We also generate a proposed description from the contents of the key that
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* can be used to name the key if the user doesn't want to provide one.
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*/
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static int asymmetric_key_preparse(struct key_preparsed_payload *prep)
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{
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struct asymmetric_key_parser *parser;
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int ret;
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pr_devel("==>%s()\n", __func__);
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if (prep->datalen == 0)
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return -EINVAL;
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down_read(&asymmetric_key_parsers_sem);
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ret = -EBADMSG;
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list_for_each_entry(parser, &asymmetric_key_parsers, link) {
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pr_debug("Trying parser '%s'\n", parser->name);
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ret = parser->parse(prep);
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if (ret != -EBADMSG) {
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pr_debug("Parser recognised the format (ret %d)\n",
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ret);
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break;
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}
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}
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up_read(&asymmetric_key_parsers_sem);
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pr_devel("<==%s() = %d\n", __func__, ret);
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return ret;
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}
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/*
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* Clean up the key ID list
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*/
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static void asymmetric_key_free_kids(struct asymmetric_key_ids *kids)
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{
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int i;
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if (kids) {
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for (i = 0; i < ARRAY_SIZE(kids->id); i++)
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kfree(kids->id[i]);
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kfree(kids);
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}
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}
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/*
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* Clean up the preparse data
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*/
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static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep)
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{
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struct asymmetric_key_subtype *subtype = prep->payload.data[asym_subtype];
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struct asymmetric_key_ids *kids = prep->payload.data[asym_key_ids];
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pr_devel("==>%s()\n", __func__);
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if (subtype) {
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subtype->destroy(prep->payload.data[asym_crypto],
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prep->payload.data[asym_auth]);
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module_put(subtype->owner);
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}
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asymmetric_key_free_kids(kids);
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kfree(prep->description);
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}
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/*
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* dispose of the data dangling from the corpse of a asymmetric key
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*/
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static void asymmetric_key_destroy(struct key *key)
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{
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struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
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struct asymmetric_key_ids *kids = key->payload.data[asym_key_ids];
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void *data = key->payload.data[asym_crypto];
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void *auth = key->payload.data[asym_auth];
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key->payload.data[asym_crypto] = NULL;
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key->payload.data[asym_subtype] = NULL;
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key->payload.data[asym_key_ids] = NULL;
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key->payload.data[asym_auth] = NULL;
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if (subtype) {
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subtype->destroy(data, auth);
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module_put(subtype->owner);
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}
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asymmetric_key_free_kids(kids);
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}
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struct key_type key_type_asymmetric = {
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.name = "asymmetric",
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.preparse = asymmetric_key_preparse,
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.free_preparse = asymmetric_key_free_preparse,
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.instantiate = generic_key_instantiate,
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.match_preparse = asymmetric_key_match_preparse,
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.match_free = asymmetric_key_match_free,
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.destroy = asymmetric_key_destroy,
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.describe = asymmetric_key_describe,
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};
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EXPORT_SYMBOL_GPL(key_type_asymmetric);
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/**
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* register_asymmetric_key_parser - Register a asymmetric key blob parser
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* @parser: The parser to register
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*/
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int register_asymmetric_key_parser(struct asymmetric_key_parser *parser)
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{
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struct asymmetric_key_parser *cursor;
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int ret;
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down_write(&asymmetric_key_parsers_sem);
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list_for_each_entry(cursor, &asymmetric_key_parsers, link) {
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if (strcmp(cursor->name, parser->name) == 0) {
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pr_err("Asymmetric key parser '%s' already registered\n",
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parser->name);
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ret = -EEXIST;
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goto out;
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}
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}
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list_add_tail(&parser->link, &asymmetric_key_parsers);
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pr_notice("Asymmetric key parser '%s' registered\n", parser->name);
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ret = 0;
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out:
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up_write(&asymmetric_key_parsers_sem);
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return ret;
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}
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EXPORT_SYMBOL_GPL(register_asymmetric_key_parser);
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/**
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* unregister_asymmetric_key_parser - Unregister a asymmetric key blob parser
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* @parser: The parser to unregister
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*/
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void unregister_asymmetric_key_parser(struct asymmetric_key_parser *parser)
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{
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down_write(&asymmetric_key_parsers_sem);
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list_del(&parser->link);
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up_write(&asymmetric_key_parsers_sem);
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pr_notice("Asymmetric key parser '%s' unregistered\n", parser->name);
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}
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EXPORT_SYMBOL_GPL(unregister_asymmetric_key_parser);
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/*
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* Module stuff
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*/
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static int __init asymmetric_key_init(void)
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{
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return register_key_type(&key_type_asymmetric);
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}
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static void __exit asymmetric_key_cleanup(void)
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{
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unregister_key_type(&key_type_asymmetric);
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}
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module_init(asymmetric_key_init);
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module_exit(asymmetric_key_cleanup);
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