From: "Jason A. Donenfeld" Jason@zx2c4.com
stable inclusion from stable-v5.10.119 commit 849e7b744cf2c6bfc47ebb099e29bd3e7b783182 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6BB
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit 5acd35487dc911541672b3ffc322851769c32a56 upstream.
We previously rolled our own randomness readiness notifier, which only has two users in the whole kernel. Replace this with a more standard atomic notifier block that serves the same purpose with less code. Also unexport the symbols, because no modules use it, only unconditional builtins. The only drawback is that it's possible for a notification handler returning the "stop" code to prevent further processing, but given that there are only two users, and that we're unexporting this anyway, that doesn't seem like a significant drawback for the simplification we receive here.
Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Theodore Ts'o tytso@mit.edu Reviewed-by: Dominik Brodowski linux@dominikbrodowski.net [Jason: for stable, also backported to crypto/drbg.c, not unexporting.] Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Acked-by: Xie XiuQi xiexiuqi@huawei.com --- crypto/drbg.c | 17 +++++------ drivers/char/random.c | 69 +++++++++++++----------------------------- include/crypto/drbg.h | 2 +- include/linux/random.h | 10 ++---- lib/random32.c | 13 +++++--- lib/vsprintf.c | 10 +++--- 6 files changed, 47 insertions(+), 74 deletions(-)
diff --git a/crypto/drbg.c b/crypto/drbg.c index 3132967a1749..19ea8d6628ff 100644 --- a/crypto/drbg.c +++ b/crypto/drbg.c @@ -1490,12 +1490,13 @@ static int drbg_generate_long(struct drbg_state *drbg, return 0; }
-static void drbg_schedule_async_seed(struct random_ready_callback *rdy) +static int drbg_schedule_async_seed(struct notifier_block *nb, unsigned long action, void *data) { - struct drbg_state *drbg = container_of(rdy, struct drbg_state, + struct drbg_state *drbg = container_of(nb, struct drbg_state, random_ready);
schedule_work(&drbg->seed_work); + return 0; }
static int drbg_prepare_hrng(struct drbg_state *drbg) @@ -1510,10 +1511,8 @@ static int drbg_prepare_hrng(struct drbg_state *drbg)
INIT_WORK(&drbg->seed_work, drbg_async_seed);
- drbg->random_ready.owner = THIS_MODULE; - drbg->random_ready.func = drbg_schedule_async_seed; - - err = add_random_ready_callback(&drbg->random_ready); + drbg->random_ready.notifier_call = drbg_schedule_async_seed; + err = register_random_ready_notifier(&drbg->random_ready);
switch (err) { case 0: @@ -1524,7 +1523,7 @@ static int drbg_prepare_hrng(struct drbg_state *drbg) fallthrough;
default: - drbg->random_ready.func = NULL; + drbg->random_ready.notifier_call = NULL; return err; }
@@ -1628,8 +1627,8 @@ static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers, */ static int drbg_uninstantiate(struct drbg_state *drbg) { - if (drbg->random_ready.func) { - del_random_ready_callback(&drbg->random_ready); + if (drbg->random_ready.notifier_call) { + unregister_random_ready_notifier(&drbg->random_ready); cancel_work_sync(&drbg->seed_work); }
diff --git a/drivers/char/random.c b/drivers/char/random.c index ee430c1753a9..1421bd53f576 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -83,8 +83,8 @@ static int crng_init = 0; /* 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); +static DEFINE_SPINLOCK(random_ready_chain_lock); +static RAW_NOTIFIER_HEAD(random_ready_chain);
/* Control how we warn userspace. */ static struct ratelimit_state unseeded_warning = @@ -147,72 +147,45 @@ EXPORT_SYMBOL(wait_for_random_bytes); * * 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) +int register_random_ready_notifier(struct notifier_block *nb) { - struct module *owner; unsigned long flags; - int err = -EALREADY; + int ret = -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 ret;
- return err; + spin_lock_irqsave(&random_ready_chain_lock, flags); + if (!crng_ready()) + ret = raw_notifier_chain_register(&random_ready_chain, nb); + spin_unlock_irqrestore(&random_ready_chain_lock, flags); + return ret; } -EXPORT_SYMBOL(add_random_ready_callback); +EXPORT_SYMBOL(register_random_ready_notifier);
/* * Delete a previously registered readiness callback function. */ -void del_random_ready_callback(struct random_ready_callback *rdy) +int unregister_random_ready_notifier(struct notifier_block *nb) { 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); + int ret;
- module_put(owner); + spin_lock_irqsave(&random_ready_chain_lock, flags); + ret = raw_notifier_chain_unregister(&random_ready_chain, nb); + spin_unlock_irqrestore(&random_ready_chain_lock, flags); + return ret; } -EXPORT_SYMBOL(del_random_ready_callback); +EXPORT_SYMBOL(unregister_random_ready_notifier);
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); + spin_lock_irqsave(&random_ready_chain_lock, flags); + raw_notifier_call_chain(&random_ready_chain, 0, NULL); + spin_unlock_irqrestore(&random_ready_chain_lock, flags); }
#define warn_unseeded_randomness(previous) \ diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h index c4165126937e..88e4d145f7cd 100644 --- a/include/crypto/drbg.h +++ b/include/crypto/drbg.h @@ -136,7 +136,7 @@ struct drbg_state { const struct drbg_state_ops *d_ops; const struct drbg_core *core; struct drbg_string test_data; - struct random_ready_callback random_ready; + struct notifier_block random_ready; };
static inline __u8 drbg_statelen(struct drbg_state *drbg) diff --git a/include/linux/random.h b/include/linux/random.h index 6148b8d1ccf3..d4abda9e2348 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -10,11 +10,7 @@
#include <uapi/linux/random.h>
-struct random_ready_callback { - struct list_head list; - void (*func)(struct random_ready_callback *rdy); - struct module *owner; -}; +struct notifier_block;
extern void add_device_randomness(const void *, size_t); extern void add_bootloader_randomness(const void *, size_t); @@ -39,8 +35,8 @@ extern void get_random_bytes(void *buf, size_t nbytes); extern int wait_for_random_bytes(void); extern int __init rand_initialize(void); extern bool rng_is_initialized(void); -extern int add_random_ready_callback(struct random_ready_callback *rdy); -extern void del_random_ready_callback(struct random_ready_callback *rdy); +extern int register_random_ready_notifier(struct notifier_block *nb); +extern int unregister_random_ready_notifier(struct notifier_block *nb); extern size_t __must_check get_random_bytes_arch(void *buf, size_t nbytes);
#ifndef MODULE diff --git a/lib/random32.c b/lib/random32.c index 3c19820796d0..f0ab17c2244b 100644 --- a/lib/random32.c +++ b/lib/random32.c @@ -40,6 +40,7 @@ #include <linux/sched.h> #include <linux/bitops.h> #include <linux/slab.h> +#include <linux/notifier.h> #include <asm/unaligned.h>
/** @@ -551,9 +552,11 @@ static void prandom_reseed(struct timer_list *unused) * To avoid worrying about whether it's safe to delay that interrupt * long enough to seed all CPUs, just schedule an immediate timer event. */ -static void prandom_timer_start(struct random_ready_callback *unused) +static int prandom_timer_start(struct notifier_block *nb, + unsigned long action, void *data) { mod_timer(&seed_timer, jiffies); + return 0; }
#ifdef CONFIG_RANDOM32_SELFTEST @@ -617,13 +620,13 @@ core_initcall(prandom32_state_selftest); */ static int __init prandom_init_late(void) { - static struct random_ready_callback random_ready = { - .func = prandom_timer_start + static struct notifier_block random_ready = { + .notifier_call = prandom_timer_start }; - int ret = add_random_ready_callback(&random_ready); + int ret = register_random_ready_notifier(&random_ready);
if (ret == -EALREADY) { - prandom_timer_start(&random_ready); + prandom_timer_start(&random_ready, 0, NULL); ret = 0; } return ret; diff --git a/lib/vsprintf.c b/lib/vsprintf.c index e5751a33dfa0..3ca1cb6f50d7 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -756,14 +756,16 @@ static void enable_ptr_key_workfn(struct work_struct *work)
static DECLARE_WORK(enable_ptr_key_work, enable_ptr_key_workfn);
-static void fill_random_ptr_key(struct random_ready_callback *unused) +static int fill_random_ptr_key(struct notifier_block *nb, + unsigned long action, void *data) { /* This may be in an interrupt handler. */ queue_work(system_unbound_wq, &enable_ptr_key_work); + return 0; }
-static struct random_ready_callback random_ready = { - .func = fill_random_ptr_key +static struct notifier_block random_ready = { + .notifier_call = fill_random_ptr_key };
static int __init initialize_ptr_random(void) @@ -777,7 +779,7 @@ static int __init initialize_ptr_random(void) return 0; }
- ret = add_random_ready_callback(&random_ready); + ret = register_random_ready_notifier(&random_ready); if (!ret) { return 0; } else if (ret == -EALREADY) {