linux-stable/security/integrity/ima/ima_queue_keys.c
Christian Brauner 39f60c1cce
fs: port xattr to mnt_idmap
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:28 +01:00

177 lines
4 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2019 Microsoft Corporation
*
* Author: Lakshmi Ramasubramanian (nramas@linux.microsoft.com)
*
* File: ima_queue_keys.c
* Enables deferred processing of keys
*/
#include <linux/user_namespace.h>
#include <linux/workqueue.h>
#include <keys/asymmetric-type.h>
#include "ima.h"
/*
* Flag to indicate whether a key can be processed
* right away or should be queued for processing later.
*/
static bool ima_process_keys;
/*
* To synchronize access to the list of keys that need to be measured
*/
static DEFINE_MUTEX(ima_keys_lock);
static LIST_HEAD(ima_keys);
/*
* If custom IMA policy is not loaded then keys queued up
* for measurement should be freed. This worker is used
* for handling this scenario.
*/
static long ima_key_queue_timeout = 300000; /* 5 Minutes */
static void ima_keys_handler(struct work_struct *work);
static DECLARE_DELAYED_WORK(ima_keys_delayed_work, ima_keys_handler);
static bool timer_expired;
/*
* This worker function frees keys that may still be
* queued up in case custom IMA policy was not loaded.
*/
static void ima_keys_handler(struct work_struct *work)
{
timer_expired = true;
ima_process_queued_keys();
}
/*
* This function sets up a worker to free queued keys in case
* custom IMA policy was never loaded.
*/
void ima_init_key_queue(void)
{
schedule_delayed_work(&ima_keys_delayed_work,
msecs_to_jiffies(ima_key_queue_timeout));
}
static void ima_free_key_entry(struct ima_key_entry *entry)
{
if (entry) {
kfree(entry->payload);
kfree(entry->keyring_name);
kfree(entry);
}
}
static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
const void *payload,
size_t payload_len)
{
int rc = 0;
const char *audit_cause = "ENOMEM";
struct ima_key_entry *entry;
entry = kzalloc(sizeof(*entry), GFP_KERNEL);
if (entry) {
entry->payload = kmemdup(payload, payload_len, GFP_KERNEL);
entry->keyring_name = kstrdup(keyring->description,
GFP_KERNEL);
entry->payload_len = payload_len;
}
if ((entry == NULL) || (entry->payload == NULL) ||
(entry->keyring_name == NULL)) {
rc = -ENOMEM;
goto out;
}
INIT_LIST_HEAD(&entry->list);
out:
if (rc) {
integrity_audit_message(AUDIT_INTEGRITY_PCR, NULL,
keyring->description,
func_measure_str(KEY_CHECK),
audit_cause, rc, 0, rc);
ima_free_key_entry(entry);
entry = NULL;
}
return entry;
}
bool ima_queue_key(struct key *keyring, const void *payload,
size_t payload_len)
{
bool queued = false;
struct ima_key_entry *entry;
entry = ima_alloc_key_entry(keyring, payload, payload_len);
if (!entry)
return false;
mutex_lock(&ima_keys_lock);
if (!ima_process_keys) {
list_add_tail(&entry->list, &ima_keys);
queued = true;
}
mutex_unlock(&ima_keys_lock);
if (!queued)
ima_free_key_entry(entry);
return queued;
}
/*
* ima_process_queued_keys() - process keys queued for measurement
*
* This function sets ima_process_keys to true and processes queued keys.
* From here on keys will be processed right away (not queued).
*/
void ima_process_queued_keys(void)
{
struct ima_key_entry *entry, *tmp;
bool process = false;
if (ima_process_keys)
return;
/*
* Since ima_process_keys is set to true, any new key will be
* processed immediately and not be queued to ima_keys list.
* First one setting the ima_process_keys flag to true will
* process the queued keys.
*/
mutex_lock(&ima_keys_lock);
if (!ima_process_keys) {
ima_process_keys = true;
process = true;
}
mutex_unlock(&ima_keys_lock);
if (!process)
return;
if (!timer_expired)
cancel_delayed_work_sync(&ima_keys_delayed_work);
list_for_each_entry_safe(entry, tmp, &ima_keys, list) {
if (!timer_expired)
process_buffer_measurement(&nop_mnt_idmap, NULL,
entry->payload,
entry->payload_len,
entry->keyring_name,
KEY_CHECK, 0,
entry->keyring_name,
false, NULL, 0);
list_del(&entry->list);
ima_free_key_entry(entry);
}
}
inline bool ima_should_queue_key(void)
{
return !ima_process_keys;
}