Commit d54e17b4 authored by Mimi Zohar's avatar Mimi Zohar

Merge branch 'next-integrity.defer-measuring-keys' into next-integrity

From patch set cover letter:

The IMA subsystem supports measuring asymmetric keys when the key is
created or updated[1]. But keys created or updated before a custom IMA
policy is loaded are currently not measured.  This includes keys added,
for instance, to either the .ima or .builtin_trusted_keys keyrings, which
happens early in the boot process.

Measuring the early boot keys, by design, requires loading a custom IMA
policy.  This change adds support for queuing keys created or updated
before a custom IMA policy is loaded.  The queued keys are processed when
a custom policy is loaded.  Keys created or updated after a custom policy
is loaded are measured immediately (not queued).  In the case when a
custom policy is not loaded within 5 minutes of IMA initialization, the
queued keys are freed.

[1] https://lore.kernel.org/linux-integrity/20191211164707.4698-1-nramas@linux.microsoft.com/
parents 5c7bac9f 5b3014b9
......@@ -316,3 +316,9 @@ config IMA_MEASURE_ASYMMETRIC_KEYS
depends on IMA
depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE=y
default y
config IMA_QUEUE_EARLY_BOOT_KEYS
bool
depends on IMA_MEASURE_ASYMMETRIC_KEYS
depends on SYSTEM_TRUSTED_KEYRING
default y
......@@ -13,3 +13,4 @@ ima-$(CONFIG_IMA_APPRAISE_MODSIG) += ima_modsig.o
ima-$(CONFIG_HAVE_IMA_KEXEC) += ima_kexec.o
obj-$(CONFIG_IMA_BLACKLIST_KEYRING) += ima_mok.o
obj-$(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) += ima_asymmetric_keys.o
obj-$(CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS) += ima_queue_keys.o
......@@ -205,6 +205,30 @@ extern const char *const func_tokens[];
struct modsig;
#ifdef CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS
/*
* To track keys that need to be measured.
*/
struct ima_key_entry {
struct list_head list;
void *payload;
size_t payload_len;
char *keyring_name;
};
void ima_init_key_queue(void);
bool ima_should_queue_key(void);
bool ima_queue_key(struct key *keyring, const void *payload,
size_t payload_len);
void ima_process_queued_keys(void);
#else
static inline void ima_init_key_queue(void) {}
static inline bool ima_should_queue_key(void) { return false; }
static inline bool ima_queue_key(struct key *keyring,
const void *payload,
size_t payload_len) { return false; }
static inline void ima_process_queued_keys(void) {}
#endif /* CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS */
/* LIM API function definitions */
int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid,
int mask, enum ima_hooks func, int *pcr,
......
......@@ -30,6 +30,8 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key,
const void *payload, size_t payload_len,
unsigned long flags, bool create)
{
bool queued = false;
/* Only asymmetric keys are handled by this hook. */
if (key->type != &key_type_asymmetric)
return;
......@@ -37,6 +39,12 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key,
if (!payload || (payload_len == 0))
return;
if (ima_should_queue_key())
queued = ima_queue_key(keyring, payload, payload_len);
if (queued)
return;
/*
* keyring->description points to the name of the keyring
* (such as ".builtin_trusted_keys", ".ima", etc.) to
......
......@@ -131,5 +131,11 @@ int __init ima_init(void)
ima_init_policy();
return ima_fs_init();
rc = ima_fs_init();
if (rc != 0)
return rc;
ima_init_key_queue();
return rc;
}
......@@ -809,6 +809,9 @@ void ima_update_policy(void)
kfree(arch_policy_entry);
}
ima_update_policy_flag();
/* Custom IMA policy has been loaded */
ima_process_queued_keys();
}
/* Keep the enumeration in sync with the policy_tokens! */
......
// 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
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#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;
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) {
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(entry->payload,
entry->payload_len,
entry->keyring_name,
KEY_CHECK, 0,
entry->keyring_name);
list_del(&entry->list);
ima_free_key_entry(entry);
}
}
inline bool ima_should_queue_key(void)
{
return !ima_process_keys;
}
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