![David Howells](/assets/img/avatar_default.png)
In the request_key() upcall mechanism there's a dependency loop by which if a key type driver overrides the ->request_key hook and the userspace side manages to lose the authorisation key, the auth key and the internal construction record (struct key_construction) can keep each other pinned. Fix this by the following changes: (1) Killing off the construction record and using the auth key instead. (2) Including the operation name in the auth key payload and making the payload available outside of security/keys/. (3) The ->request_key hook is given the authkey instead of the cons record and operation name. Changes (2) and (3) allow the auth key to naturally be cleaned up if the keyring it is in is destroyed or cleared or the auth key is unlinked. Fixes: 7ee02a316600 ("keys: Fix dependency loop between construction record and auth key") Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <james.morris@microsoft.com>
194 lines
6.6 KiB
C
194 lines
6.6 KiB
C
/* Definitions for key type implementations
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*
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* Copyright (C) 2007 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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#ifndef _LINUX_KEY_TYPE_H
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#define _LINUX_KEY_TYPE_H
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#include <linux/key.h>
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#include <linux/errno.h>
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#ifdef CONFIG_KEYS
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struct kernel_pkey_query;
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struct kernel_pkey_params;
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/*
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* Pre-parsed payload, used by key add, update and instantiate.
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*
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* This struct will be cleared and data and datalen will be set with the data
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* and length parameters from the caller and quotalen will be set from
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* def_datalen from the key type. Then if the preparse() op is provided by the
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* key type, that will be called. Then the struct will be passed to the
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* instantiate() or the update() op.
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*
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* If the preparse() op is given, the free_preparse() op will be called to
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* clear the contents.
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*/
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struct key_preparsed_payload {
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char *description; /* Proposed key description (or NULL) */
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union key_payload payload; /* Proposed payload */
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const void *data; /* Raw data */
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size_t datalen; /* Raw datalen */
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size_t quotalen; /* Quota length for proposed payload */
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time64_t expiry; /* Expiry time of key */
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} __randomize_layout;
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typedef int (*request_key_actor_t)(struct key *auth_key, void *aux);
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/*
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* Preparsed matching criterion.
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*/
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struct key_match_data {
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/* Comparison function, defaults to exact description match, but can be
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* overridden by type->match_preparse(). Should return true if a match
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* is found and false if not.
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*/
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bool (*cmp)(const struct key *key,
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const struct key_match_data *match_data);
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const void *raw_data; /* Raw match data */
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void *preparsed; /* For ->match_preparse() to stash stuff */
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unsigned lookup_type; /* Type of lookup for this search. */
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#define KEYRING_SEARCH_LOOKUP_DIRECT 0x0000 /* Direct lookup by description. */
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#define KEYRING_SEARCH_LOOKUP_ITERATE 0x0001 /* Iterative search. */
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};
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/*
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* kernel managed key type definition
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*/
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struct key_type {
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/* name of the type */
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const char *name;
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/* default payload length for quota precalculation (optional)
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* - this can be used instead of calling key_payload_reserve(), that
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* function only needs to be called if the real datalen is different
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*/
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size_t def_datalen;
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/* vet a description */
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int (*vet_description)(const char *description);
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/* Preparse the data blob from userspace that is to be the payload,
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* generating a proposed description and payload that will be handed to
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* the instantiate() and update() ops.
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*/
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int (*preparse)(struct key_preparsed_payload *prep);
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/* Free a preparse data structure.
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*/
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void (*free_preparse)(struct key_preparsed_payload *prep);
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/* instantiate a key of this type
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* - this method should call key_payload_reserve() to determine if the
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* user's quota will hold the payload
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*/
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int (*instantiate)(struct key *key, struct key_preparsed_payload *prep);
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/* update a key of this type (optional)
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* - this method should call key_payload_reserve() to recalculate the
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* quota consumption
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* - the key must be locked against read when modifying
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*/
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int (*update)(struct key *key, struct key_preparsed_payload *prep);
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/* Preparse the data supplied to ->match() (optional). The
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* data to be preparsed can be found in match_data->raw_data.
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* The lookup type can also be set by this function.
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*/
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int (*match_preparse)(struct key_match_data *match_data);
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/* Free preparsed match data (optional). This should be supplied it
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* ->match_preparse() is supplied. */
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void (*match_free)(struct key_match_data *match_data);
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/* clear some of the data from a key on revokation (optional)
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* - the key's semaphore will be write-locked by the caller
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*/
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void (*revoke)(struct key *key);
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/* clear the data from a key (optional) */
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void (*destroy)(struct key *key);
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/* describe a key */
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void (*describe)(const struct key *key, struct seq_file *p);
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/* read a key's data (optional)
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* - permission checks will be done by the caller
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* - the key's semaphore will be readlocked by the caller
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* - should return the amount of data that could be read, no matter how
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* much is copied into the buffer
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* - shouldn't do the copy if the buffer is NULL
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*/
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long (*read)(const struct key *key, char __user *buffer, size_t buflen);
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/* handle request_key() for this type instead of invoking
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* /sbin/request-key (optional)
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* - key is the key to instantiate
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* - authkey is the authority to assume when instantiating this key
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* - op is the operation to be done, usually "create"
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* - the call must not return until the instantiation process has run
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* its course
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*/
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request_key_actor_t request_key;
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/* Look up a keyring access restriction (optional)
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*
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* - NULL is a valid return value (meaning the requested restriction
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* is known but will never block addition of a key)
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* - should return -EINVAL if the restriction is unknown
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*/
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struct key_restriction *(*lookup_restriction)(const char *params);
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/* Asymmetric key accessor functions. */
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int (*asym_query)(const struct kernel_pkey_params *params,
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struct kernel_pkey_query *info);
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int (*asym_eds_op)(struct kernel_pkey_params *params,
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const void *in, void *out);
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int (*asym_verify_signature)(struct kernel_pkey_params *params,
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const void *in, const void *in2);
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/* internal fields */
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struct list_head link; /* link in types list */
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struct lock_class_key lock_class; /* key->sem lock class */
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} __randomize_layout;
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extern struct key_type key_type_keyring;
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extern int register_key_type(struct key_type *ktype);
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extern void unregister_key_type(struct key_type *ktype);
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extern int key_payload_reserve(struct key *key, size_t datalen);
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extern int key_instantiate_and_link(struct key *key,
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const void *data,
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size_t datalen,
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struct key *keyring,
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struct key *authkey);
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extern int key_reject_and_link(struct key *key,
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unsigned timeout,
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unsigned error,
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struct key *keyring,
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struct key *authkey);
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extern void complete_request_key(struct key *authkey, int error);
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static inline int key_negate_and_link(struct key *key,
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unsigned timeout,
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struct key *keyring,
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struct key *authkey)
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{
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return key_reject_and_link(key, timeout, ENOKEY, keyring, authkey);
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}
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extern int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep);
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#endif /* CONFIG_KEYS */
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#endif /* _LINUX_KEY_TYPE_H */
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