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![Waiman Long](/assets/img/avatar_default.png)
As said by Linus: A symmetric naming is only helpful if it implies symmetries in use. Otherwise it's actively misleading. In "kzalloc()", the z is meaningful and an important part of what the caller wants. In "kzfree()", the z is actively detrimental, because maybe in the future we really _might_ want to use that "memfill(0xdeadbeef)" or something. The "zero" part of the interface isn't even _relevant_. The main reason that kzfree() exists is to clear sensitive information that should not be leaked to other future users of the same memory objects. Rename kzfree() to kfree_sensitive() to follow the example of the recently added kvfree_sensitive() and make the intention of the API more explicit. In addition, memzero_explicit() is used to clear the memory to make sure that it won't get optimized away by the compiler. The renaming is done by using the command sequence: git grep -w --name-only kzfree |\ xargs sed -i 's/kzfree/kfree_sensitive/' followed by some editing of the kfree_sensitive() kerneldoc and adding a kzfree backward compatibility macro in slab.h. [akpm@linux-foundation.org: fs/crypto/inline_crypt.c needs linux/slab.h] [akpm@linux-foundation.org: fix fs/crypto/inline_crypt.c some more] Suggested-by: Joe Perches <joe@perches.com> Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: David Howells <dhowells@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Cc: James Morris <jmorris@namei.org> Cc: "Serge E. Hallyn" <serge@hallyn.com> Cc: Joe Perches <joe@perches.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: David Rientjes <rientjes@google.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: "Jason A . Donenfeld" <Jason@zx2c4.com> Link: http://lkml.kernel.org/r/20200616154311.12314-3-longman@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
207 lines
4.6 KiB
C
207 lines
4.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* user_defined.c: user defined key type
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*
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* Copyright (C) 2004 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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#include <linux/export.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/seq_file.h>
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#include <linux/err.h>
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#include <keys/user-type.h>
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#include <linux/uaccess.h>
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#include "internal.h"
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static int logon_vet_description(const char *desc);
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/*
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* user defined keys take an arbitrary string as the description and an
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* arbitrary blob of data as the payload
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*/
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struct key_type key_type_user = {
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.name = "user",
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.preparse = user_preparse,
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.free_preparse = user_free_preparse,
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.instantiate = generic_key_instantiate,
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.update = user_update,
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.revoke = user_revoke,
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.destroy = user_destroy,
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.describe = user_describe,
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.read = user_read,
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};
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EXPORT_SYMBOL_GPL(key_type_user);
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/*
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* This key type is essentially the same as key_type_user, but it does
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* not define a .read op. This is suitable for storing username and
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* password pairs in the keyring that you do not want to be readable
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* from userspace.
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*/
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struct key_type key_type_logon = {
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.name = "logon",
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.preparse = user_preparse,
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.free_preparse = user_free_preparse,
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.instantiate = generic_key_instantiate,
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.update = user_update,
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.revoke = user_revoke,
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.destroy = user_destroy,
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.describe = user_describe,
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.vet_description = logon_vet_description,
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};
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EXPORT_SYMBOL_GPL(key_type_logon);
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/*
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* Preparse a user defined key payload
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*/
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int user_preparse(struct key_preparsed_payload *prep)
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{
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struct user_key_payload *upayload;
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size_t datalen = prep->datalen;
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if (datalen <= 0 || datalen > 32767 || !prep->data)
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return -EINVAL;
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upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
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if (!upayload)
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return -ENOMEM;
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/* attach the data */
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prep->quotalen = datalen;
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prep->payload.data[0] = upayload;
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upayload->datalen = datalen;
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memcpy(upayload->data, prep->data, datalen);
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return 0;
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}
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EXPORT_SYMBOL_GPL(user_preparse);
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/*
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* Free a preparse of a user defined key payload
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*/
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void user_free_preparse(struct key_preparsed_payload *prep)
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{
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kfree_sensitive(prep->payload.data[0]);
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}
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EXPORT_SYMBOL_GPL(user_free_preparse);
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static void user_free_payload_rcu(struct rcu_head *head)
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{
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struct user_key_payload *payload;
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payload = container_of(head, struct user_key_payload, rcu);
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kfree_sensitive(payload);
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}
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/*
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* update a user defined key
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* - the key's semaphore is write-locked
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*/
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int user_update(struct key *key, struct key_preparsed_payload *prep)
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{
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struct user_key_payload *zap = NULL;
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int ret;
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/* check the quota and attach the new data */
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ret = key_payload_reserve(key, prep->datalen);
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if (ret < 0)
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return ret;
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/* attach the new data, displacing the old */
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key->expiry = prep->expiry;
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if (key_is_positive(key))
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zap = dereference_key_locked(key);
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rcu_assign_keypointer(key, prep->payload.data[0]);
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prep->payload.data[0] = NULL;
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if (zap)
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call_rcu(&zap->rcu, user_free_payload_rcu);
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return ret;
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}
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EXPORT_SYMBOL_GPL(user_update);
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/*
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* dispose of the links from a revoked keyring
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* - called with the key sem write-locked
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*/
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void user_revoke(struct key *key)
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{
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struct user_key_payload *upayload = user_key_payload_locked(key);
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/* clear the quota */
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key_payload_reserve(key, 0);
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if (upayload) {
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rcu_assign_keypointer(key, NULL);
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call_rcu(&upayload->rcu, user_free_payload_rcu);
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}
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}
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EXPORT_SYMBOL(user_revoke);
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/*
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* dispose of the data dangling from the corpse of a user key
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*/
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void user_destroy(struct key *key)
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{
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struct user_key_payload *upayload = key->payload.data[0];
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kfree_sensitive(upayload);
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}
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EXPORT_SYMBOL_GPL(user_destroy);
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/*
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* describe the user key
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*/
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void user_describe(const struct key *key, struct seq_file *m)
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{
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seq_puts(m, key->description);
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if (key_is_positive(key))
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seq_printf(m, ": %u", key->datalen);
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}
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EXPORT_SYMBOL_GPL(user_describe);
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/*
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* read the key data
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* - the key's semaphore is read-locked
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*/
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long user_read(const struct key *key, char *buffer, size_t buflen)
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{
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const struct user_key_payload *upayload;
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long ret;
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upayload = user_key_payload_locked(key);
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ret = upayload->datalen;
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/* we can return the data as is */
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if (buffer && buflen > 0) {
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if (buflen > upayload->datalen)
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buflen = upayload->datalen;
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memcpy(buffer, upayload->data, buflen);
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(user_read);
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/* Vet the description for a "logon" key */
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static int logon_vet_description(const char *desc)
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{
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char *p;
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/* require a "qualified" description string */
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p = strchr(desc, ':');
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if (!p)
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return -EINVAL;
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/* also reject description with ':' as first char */
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if (p == desc)
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return -EINVAL;
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return 0;
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}
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