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random: group initialization wait functions
This pulls all of the readiness waiting-focused functions into the first labeled section. No functional changes. Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld
parent
87e7d5abad
commit
5f1bb11200
1 changed files with 179 additions and 168 deletions
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@ -201,6 +201,185 @@
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#include <asm/irq_regs.h>
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#include <asm/io.h>
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/*********************************************************************
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*
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* Initialization and readiness waiting.
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*
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* Much of the RNG infrastructure is devoted to various dependencies
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* being able to wait until the RNG has collected enough entropy and
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* is ready for safe consumption.
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*
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*********************************************************************/
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/*
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* crng_init = 0 --> Uninitialized
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* 1 --> Initialized
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* 2 --> Initialized from input_pool
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*
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* crng_init is protected by base_crng->lock, and only increases
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* its value (from 0->1->2).
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*/
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static int crng_init = 0;
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#define crng_ready() (likely(crng_init > 1))
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/* Various types of waiters for crng_init->2 transition. */
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static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
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static struct fasync_struct *fasync;
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static DEFINE_SPINLOCK(random_ready_list_lock);
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static LIST_HEAD(random_ready_list);
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/* Control how we warn userspace. */
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static struct ratelimit_state unseeded_warning =
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RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3);
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static struct ratelimit_state urandom_warning =
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RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3);
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static int ratelimit_disable __read_mostly;
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module_param_named(ratelimit_disable, ratelimit_disable, int, 0644);
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MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression");
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/*
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* Returns whether or not the input pool has been seeded and thus guaranteed
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* to supply cryptographically secure random numbers. This applies to: the
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* /dev/urandom device, the get_random_bytes function, and the get_random_{u32,
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* ,u64,int,long} family of functions.
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*
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* Returns: true if the input pool has been seeded.
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* false if the input pool has not been seeded.
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*/
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bool rng_is_initialized(void)
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{
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return crng_ready();
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}
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EXPORT_SYMBOL(rng_is_initialized);
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/* Used by wait_for_random_bytes(), and considered an entropy collector, below. */
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static void try_to_generate_entropy(void);
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/*
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* Wait for the input pool to be seeded and thus guaranteed to supply
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* cryptographically secure random numbers. This applies to: the /dev/urandom
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* device, the get_random_bytes function, and the get_random_{u32,u64,int,long}
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* family of functions. Using any of these functions without first calling
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* this function forfeits the guarantee of security.
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*
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* Returns: 0 if the input pool has been seeded.
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* -ERESTARTSYS if the function was interrupted by a signal.
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*/
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int wait_for_random_bytes(void)
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{
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if (likely(crng_ready()))
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return 0;
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do {
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int ret;
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ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ);
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if (ret)
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return ret > 0 ? 0 : ret;
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try_to_generate_entropy();
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} while (!crng_ready());
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return 0;
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}
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EXPORT_SYMBOL(wait_for_random_bytes);
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/*
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* Add a callback function that will be invoked when the input
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* pool is initialised.
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*
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* returns: 0 if callback is successfully added
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* -EALREADY if pool is already initialised (callback not called)
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* -ENOENT if module for callback is not alive
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*/
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int add_random_ready_callback(struct random_ready_callback *rdy)
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{
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struct module *owner;
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unsigned long flags;
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int err = -EALREADY;
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if (crng_ready())
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return err;
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owner = rdy->owner;
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if (!try_module_get(owner))
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return -ENOENT;
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spin_lock_irqsave(&random_ready_list_lock, flags);
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if (crng_ready())
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goto out;
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owner = NULL;
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list_add(&rdy->list, &random_ready_list);
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err = 0;
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out:
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spin_unlock_irqrestore(&random_ready_list_lock, flags);
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module_put(owner);
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return err;
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}
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EXPORT_SYMBOL(add_random_ready_callback);
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/*
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* Delete a previously registered readiness callback function.
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*/
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void del_random_ready_callback(struct random_ready_callback *rdy)
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{
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unsigned long flags;
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struct module *owner = NULL;
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spin_lock_irqsave(&random_ready_list_lock, flags);
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if (!list_empty(&rdy->list)) {
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list_del_init(&rdy->list);
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owner = rdy->owner;
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}
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spin_unlock_irqrestore(&random_ready_list_lock, flags);
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module_put(owner);
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}
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EXPORT_SYMBOL(del_random_ready_callback);
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static void process_random_ready_list(void)
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{
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unsigned long flags;
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struct random_ready_callback *rdy, *tmp;
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spin_lock_irqsave(&random_ready_list_lock, flags);
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list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
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struct module *owner = rdy->owner;
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list_del_init(&rdy->list);
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rdy->func(rdy);
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module_put(owner);
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}
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spin_unlock_irqrestore(&random_ready_list_lock, flags);
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}
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#define warn_unseeded_randomness(previous) \
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_warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous))
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static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous)
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{
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#ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM
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const bool print_once = false;
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#else
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static bool print_once __read_mostly;
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#endif
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if (print_once || crng_ready() ||
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(previous && (caller == READ_ONCE(*previous))))
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return;
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WRITE_ONCE(*previous, caller);
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#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM
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print_once = true;
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#endif
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if (__ratelimit(&unseeded_warning))
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printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n",
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func_name, caller, crng_init);
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}
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enum {
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POOL_BITS = BLAKE2S_HASH_SIZE * 8,
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POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */
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@ -210,34 +389,8 @@ enum {
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* Static global variables
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*/
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static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
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static struct fasync_struct *fasync;
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static DEFINE_SPINLOCK(random_ready_list_lock);
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static LIST_HEAD(random_ready_list);
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/*
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* crng_init = 0 --> Uninitialized
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* 1 --> Initialized
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* 2 --> Initialized from input_pool
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*
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* crng_init is protected by primary_crng->lock, and only increases
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* its value (from 0->1->2).
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*/
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static int crng_init = 0;
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#define crng_ready() (likely(crng_init > 1))
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static int crng_init_cnt = 0;
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static void process_random_ready_list(void);
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static void _get_random_bytes(void *buf, size_t nbytes);
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static struct ratelimit_state unseeded_warning =
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RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3);
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static struct ratelimit_state urandom_warning =
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RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3);
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static int ratelimit_disable __read_mostly;
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module_param_named(ratelimit_disable, ratelimit_disable, int, 0644);
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MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression");
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/**********************************************************************
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*
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@ -322,22 +475,6 @@ static void fast_mix(u32 pool[4])
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pool[2] = c; pool[3] = d;
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}
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static void process_random_ready_list(void)
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{
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unsigned long flags;
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struct random_ready_callback *rdy, *tmp;
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spin_lock_irqsave(&random_ready_list_lock, flags);
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list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
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struct module *owner = rdy->owner;
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list_del_init(&rdy->list);
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rdy->func(rdy);
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module_put(owner);
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}
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spin_unlock_irqrestore(&random_ready_list_lock, flags);
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}
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static void credit_entropy_bits(size_t nbits)
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{
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unsigned int entropy_count, orig, add;
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@ -387,8 +524,6 @@ static DEFINE_PER_CPU(struct crng, crngs) = {
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.lock = INIT_LOCAL_LOCK(crngs.lock),
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};
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static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
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/*
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* crng_fast_load() can be called by code in the interrupt service
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* path. So we can't afford to dilly-dally. Returns the number of
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@ -909,29 +1044,6 @@ static bool drain_entropy(void *buf, size_t nbytes)
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return true;
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}
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#define warn_unseeded_randomness(previous) \
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_warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous))
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static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous)
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{
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#ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM
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const bool print_once = false;
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#else
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static bool print_once __read_mostly;
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#endif
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if (print_once || crng_ready() ||
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(previous && (caller == READ_ONCE(*previous))))
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return;
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WRITE_ONCE(*previous, caller);
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#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM
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print_once = true;
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#endif
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if (__ratelimit(&unseeded_warning))
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printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n",
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func_name, caller, crng_init);
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}
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/*
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* This function is the exported kernel interface. It returns some
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* number of good random numbers, suitable for key generation, seeding
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@ -1032,107 +1144,6 @@ static void try_to_generate_entropy(void)
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mix_pool_bytes(&stack.now, sizeof(stack.now));
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}
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/*
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* Wait for the urandom pool to be seeded and thus guaranteed to supply
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* cryptographically secure random numbers. This applies to: the /dev/urandom
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* device, the get_random_bytes function, and the get_random_{u32,u64,int,long}
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* family of functions. Using any of these functions without first calling
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* this function forfeits the guarantee of security.
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*
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* Returns: 0 if the urandom pool has been seeded.
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* -ERESTARTSYS if the function was interrupted by a signal.
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*/
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int wait_for_random_bytes(void)
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{
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if (likely(crng_ready()))
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return 0;
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do {
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int ret;
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ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ);
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if (ret)
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return ret > 0 ? 0 : ret;
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try_to_generate_entropy();
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} while (!crng_ready());
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return 0;
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}
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EXPORT_SYMBOL(wait_for_random_bytes);
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/*
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* Returns whether or not the urandom pool has been seeded and thus guaranteed
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* to supply cryptographically secure random numbers. This applies to: the
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* /dev/urandom device, the get_random_bytes function, and the get_random_{u32,
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* ,u64,int,long} family of functions.
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*
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* Returns: true if the urandom pool has been seeded.
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* false if the urandom pool has not been seeded.
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*/
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bool rng_is_initialized(void)
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{
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return crng_ready();
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}
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EXPORT_SYMBOL(rng_is_initialized);
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/*
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* Add a callback function that will be invoked when the nonblocking
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* pool is initialised.
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*
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* returns: 0 if callback is successfully added
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* -EALREADY if pool is already initialised (callback not called)
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* -ENOENT if module for callback is not alive
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*/
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int add_random_ready_callback(struct random_ready_callback *rdy)
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{
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struct module *owner;
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unsigned long flags;
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int err = -EALREADY;
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if (crng_ready())
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return err;
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owner = rdy->owner;
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if (!try_module_get(owner))
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return -ENOENT;
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spin_lock_irqsave(&random_ready_list_lock, flags);
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if (crng_ready())
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goto out;
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owner = NULL;
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list_add(&rdy->list, &random_ready_list);
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err = 0;
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out:
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spin_unlock_irqrestore(&random_ready_list_lock, flags);
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module_put(owner);
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return err;
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}
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EXPORT_SYMBOL(add_random_ready_callback);
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/*
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* Delete a previously registered readiness callback function.
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*/
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void del_random_ready_callback(struct random_ready_callback *rdy)
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{
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unsigned long flags;
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struct module *owner = NULL;
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spin_lock_irqsave(&random_ready_list_lock, flags);
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if (!list_empty(&rdy->list)) {
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list_del_init(&rdy->list);
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owner = rdy->owner;
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}
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spin_unlock_irqrestore(&random_ready_list_lock, flags);
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module_put(owner);
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}
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EXPORT_SYMBOL(del_random_ready_callback);
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/*
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* This function will use the architecture-specific hardware random
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* number generator if it is available. It is not recommended for
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