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![Mat Martineau](/assets/img/avatar_default.png)
Add a restrict_link_by_key_or_keyring_chain link restriction that searches for signing keys in the destination keyring in addition to the signing key or keyring designated when the destination keyring was created. Userspace enables this behavior by including the "chain" option in the keyring restriction: keyctl(KEYCTL_RESTRICT_KEYRING, keyring, "asymmetric", "key_or_keyring:<signing key>:chain"); Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
611 lines
15 KiB
C
611 lines
15 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 <keys/system_keyring.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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static struct key_restriction *asymmetric_restriction_alloc(
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key_restrict_link_func_t check,
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struct key *key)
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{
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struct key_restriction *keyres =
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kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
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if (!keyres)
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return ERR_PTR(-ENOMEM);
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keyres->check = check;
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keyres->key = key;
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keyres->keytype = &key_type_asymmetric;
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return keyres;
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}
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/*
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* look up keyring restrict functions for asymmetric keys
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*/
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static struct key_restriction *asymmetric_lookup_restriction(
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const char *restriction)
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{
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char *restrict_method;
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char *parse_buf;
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char *next;
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struct key_restriction *ret = ERR_PTR(-EINVAL);
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if (strcmp("builtin_trusted", restriction) == 0)
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return asymmetric_restriction_alloc(
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restrict_link_by_builtin_trusted, NULL);
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if (strcmp("builtin_and_secondary_trusted", restriction) == 0)
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return asymmetric_restriction_alloc(
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restrict_link_by_builtin_and_secondary_trusted, NULL);
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parse_buf = kstrndup(restriction, PAGE_SIZE, GFP_KERNEL);
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if (!parse_buf)
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return ERR_PTR(-ENOMEM);
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next = parse_buf;
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restrict_method = strsep(&next, ":");
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if ((strcmp(restrict_method, "key_or_keyring") == 0) && next) {
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char *key_text;
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key_serial_t serial;
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struct key *key;
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key_restrict_link_func_t link_fn =
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restrict_link_by_key_or_keyring;
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bool allow_null_key = false;
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key_text = strsep(&next, ":");
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if (next) {
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if (strcmp(next, "chain") != 0)
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goto out;
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|
|
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;
|
|
}
|
|
|
|
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,
|
|
};
|
|
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);
|