From: "Jason A. Donenfeld" Jason@zx2c4.com
commit 5f1bb112006b104b3e2a1e1b39bbb9b2617581e6 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/char/random.c | 333 +++++++++++++++++++++++++------------------------- 1 file changed, 172 insertions(+), 161 deletions(-)
--- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -201,44 +201,197 @@ #include <asm/irq_regs.h> #include <asm/io.h>
-enum { - POOL_BITS = BLAKE2S_HASH_SIZE * 8, - POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */ -}; - -/* - * Static global variables - */ -static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); -static struct fasync_struct *fasync; - -static DEFINE_SPINLOCK(random_ready_list_lock); -static LIST_HEAD(random_ready_list); +/********************************************************************* + * + * Initialization and readiness waiting. + * + * Much of the RNG infrastructure is devoted to various dependencies + * being able to wait until the RNG has collected enough entropy and + * is ready for safe consumption. + * + *********************************************************************/
/* * crng_init = 0 --> Uninitialized * 1 --> Initialized * 2 --> Initialized from input_pool * - * crng_init is protected by primary_crng->lock, and only increases + * crng_init is protected by base_crng->lock, and only increases * its value (from 0->1->2). */ static int crng_init = 0; #define crng_ready() (likely(crng_init > 1)) -static int crng_init_cnt = 0; -static void process_random_ready_list(void); -static void _get_random_bytes(void *buf, size_t nbytes); +/* Various types of waiters for crng_init->2 transition. */ +static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); +static struct fasync_struct *fasync; +static DEFINE_SPINLOCK(random_ready_list_lock); +static LIST_HEAD(random_ready_list);
+/* Control how we warn userspace. */ static struct ratelimit_state unseeded_warning = RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3); static struct ratelimit_state urandom_warning = RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3); - static int ratelimit_disable __read_mostly; - module_param_named(ratelimit_disable, ratelimit_disable, int, 0644); MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression");
+/* + * Returns whether or not the input pool has been seeded and thus guaranteed + * to supply cryptographically secure random numbers. This applies to: the + * /dev/urandom device, the get_random_bytes function, and the get_random_{u32, + * ,u64,int,long} family of functions. + * + * Returns: true if the input pool has been seeded. + * false if the input pool has not been seeded. + */ +bool rng_is_initialized(void) +{ + return crng_ready(); +} +EXPORT_SYMBOL(rng_is_initialized); + +/* Used by wait_for_random_bytes(), and considered an entropy collector, below. */ +static void try_to_generate_entropy(void); + +/* + * Wait for the input pool to be seeded and thus guaranteed to supply + * cryptographically secure random numbers. This applies to: the /dev/urandom + * device, the get_random_bytes function, and the get_random_{u32,u64,int,long} + * family of functions. Using any of these functions without first calling + * this function forfeits the guarantee of security. + * + * Returns: 0 if the input pool has been seeded. + * -ERESTARTSYS if the function was interrupted by a signal. + */ +int wait_for_random_bytes(void) +{ + if (likely(crng_ready())) + return 0; + + do { + int ret; + ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ); + if (ret) + return ret > 0 ? 0 : ret; + + try_to_generate_entropy(); + } while (!crng_ready()); + + return 0; +} +EXPORT_SYMBOL(wait_for_random_bytes); + +/* + * Add a callback function that will be invoked when the input + * pool is initialised. + * + * returns: 0 if callback is successfully added + * -EALREADY if pool is already initialised (callback not called) + * -ENOENT if module for callback is not alive + */ +int add_random_ready_callback(struct random_ready_callback *rdy) +{ + struct module *owner; + unsigned long flags; + int err = -EALREADY; + + if (crng_ready()) + return err; + + owner = rdy->owner; + if (!try_module_get(owner)) + return -ENOENT; + + spin_lock_irqsave(&random_ready_list_lock, flags); + if (crng_ready()) + goto out; + + owner = NULL; + + list_add(&rdy->list, &random_ready_list); + err = 0; + +out: + spin_unlock_irqrestore(&random_ready_list_lock, flags); + + module_put(owner); + + return err; +} +EXPORT_SYMBOL(add_random_ready_callback); + +/* + * Delete a previously registered readiness callback function. + */ +void del_random_ready_callback(struct random_ready_callback *rdy) +{ + unsigned long flags; + struct module *owner = NULL; + + spin_lock_irqsave(&random_ready_list_lock, flags); + if (!list_empty(&rdy->list)) { + list_del_init(&rdy->list); + owner = rdy->owner; + } + spin_unlock_irqrestore(&random_ready_list_lock, flags); + + module_put(owner); +} +EXPORT_SYMBOL(del_random_ready_callback); + +static void process_random_ready_list(void) +{ + unsigned long flags; + struct random_ready_callback *rdy, *tmp; + + spin_lock_irqsave(&random_ready_list_lock, flags); + list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { + struct module *owner = rdy->owner; + + list_del_init(&rdy->list); + rdy->func(rdy); + module_put(owner); + } + spin_unlock_irqrestore(&random_ready_list_lock, flags); +} + +#define warn_unseeded_randomness(previous) \ + _warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous)) + +static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous) +{ +#ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM + const bool print_once = false; +#else + static bool print_once __read_mostly; +#endif + + if (print_once || crng_ready() || + (previous && (caller == READ_ONCE(*previous)))) + return; + WRITE_ONCE(*previous, caller); +#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM + print_once = true; +#endif + if (__ratelimit(&unseeded_warning)) + printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", + func_name, caller, crng_init); +} + + +enum { + POOL_BITS = BLAKE2S_HASH_SIZE * 8, + POOL_MIN_BITS = POOL_BITS /* No point in settling for less. */ +}; + +/* + * Static global variables + */ +static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); + +static int crng_init_cnt = 0; + /********************************************************************** * * OS independent entropy store. Here are the functions which handle @@ -322,22 +475,6 @@ static void fast_mix(u32 pool[4]) pool[2] = c; pool[3] = d; }
-static void process_random_ready_list(void) -{ - unsigned long flags; - struct random_ready_callback *rdy, *tmp; - - spin_lock_irqsave(&random_ready_list_lock, flags); - list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) { - struct module *owner = rdy->owner; - - list_del_init(&rdy->list); - rdy->func(rdy); - module_put(owner); - } - spin_unlock_irqrestore(&random_ready_list_lock, flags); -} - static void credit_entropy_bits(size_t nbits) { unsigned int entropy_count, orig, add; @@ -387,8 +524,6 @@ static DEFINE_PER_CPU(struct crng, crngs .lock = INIT_LOCAL_LOCK(crngs.lock), };
-static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); - /* * crng_fast_load() can be called by code in the interrupt service * path. So we can't afford to dilly-dally. Returns the number of @@ -909,29 +1044,6 @@ static bool drain_entropy(void *buf, siz return true; }
-#define warn_unseeded_randomness(previous) \ - _warn_unseeded_randomness(__func__, (void *)_RET_IP_, (previous)) - -static void _warn_unseeded_randomness(const char *func_name, void *caller, void **previous) -{ -#ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM - const bool print_once = false; -#else - static bool print_once __read_mostly; -#endif - - if (print_once || crng_ready() || - (previous && (caller == READ_ONCE(*previous)))) - return; - WRITE_ONCE(*previous, caller); -#ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM - print_once = true; -#endif - if (__ratelimit(&unseeded_warning)) - printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", - func_name, caller, crng_init); -} - /* * This function is the exported kernel interface. It returns some * number of good random numbers, suitable for key generation, seeding @@ -1033,107 +1145,6 @@ static void try_to_generate_entropy(void }
/* - * Wait for the urandom pool to be seeded and thus guaranteed to supply - * cryptographically secure random numbers. This applies to: the /dev/urandom - * device, the get_random_bytes function, and the get_random_{u32,u64,int,long} - * family of functions. Using any of these functions without first calling - * this function forfeits the guarantee of security. - * - * Returns: 0 if the urandom pool has been seeded. - * -ERESTARTSYS if the function was interrupted by a signal. - */ -int wait_for_random_bytes(void) -{ - if (likely(crng_ready())) - return 0; - - do { - int ret; - ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ); - if (ret) - return ret > 0 ? 0 : ret; - - try_to_generate_entropy(); - } while (!crng_ready()); - - return 0; -} -EXPORT_SYMBOL(wait_for_random_bytes); - -/* - * Returns whether or not the urandom pool has been seeded and thus guaranteed - * to supply cryptographically secure random numbers. This applies to: the - * /dev/urandom device, the get_random_bytes function, and the get_random_{u32, - * ,u64,int,long} family of functions. - * - * Returns: true if the urandom pool has been seeded. - * false if the urandom pool has not been seeded. - */ -bool rng_is_initialized(void) -{ - return crng_ready(); -} -EXPORT_SYMBOL(rng_is_initialized); - -/* - * Add a callback function that will be invoked when the nonblocking - * pool is initialised. - * - * returns: 0 if callback is successfully added - * -EALREADY if pool is already initialised (callback not called) - * -ENOENT if module for callback is not alive - */ -int add_random_ready_callback(struct random_ready_callback *rdy) -{ - struct module *owner; - unsigned long flags; - int err = -EALREADY; - - if (crng_ready()) - return err; - - owner = rdy->owner; - if (!try_module_get(owner)) - return -ENOENT; - - spin_lock_irqsave(&random_ready_list_lock, flags); - if (crng_ready()) - goto out; - - owner = NULL; - - list_add(&rdy->list, &random_ready_list); - err = 0; - -out: - spin_unlock_irqrestore(&random_ready_list_lock, flags); - - module_put(owner); - - return err; -} -EXPORT_SYMBOL(add_random_ready_callback); - -/* - * Delete a previously registered readiness callback function. - */ -void del_random_ready_callback(struct random_ready_callback *rdy) -{ - unsigned long flags; - struct module *owner = NULL; - - spin_lock_irqsave(&random_ready_list_lock, flags); - if (!list_empty(&rdy->list)) { - list_del_init(&rdy->list); - owner = rdy->owner; - } - spin_unlock_irqrestore(&random_ready_list_lock, flags); - - module_put(owner); -} -EXPORT_SYMBOL(del_random_ready_callback); - -/* * This function will use the architecture-specific hardware random * number generator if it is available. It is not recommended for * use. Use get_random_bytes() instead. It returns the number of