From 775f4b297b780601e61787b766f306ed3e1d23eb Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Mon, 2 Jul 2012 07:52:16 -0400 Subject: random: make 'add_interrupt_randomness()' do something sane We've been moving away from add_interrupt_randomness() for various reasons: it's too expensive to do on every interrupt, and flooding the CPU with interrupts could theoretically cause bogus floods of entropy from a somewhat externally controllable source. This solves both problems by limiting the actual randomness addition to just once a second or after 64 interrupts, whicever comes first. During that time, the interrupt cycle data is buffered up in a per-cpu pool. Also, we make sure the the nonblocking pool used by urandom is initialized before we start feeding the normal input pool. This assures that /dev/urandom is returning unpredictable data as soon as possible. (Based on an original patch by Linus, but significantly modified by tytso.) Tested-by: Eric Wustrow Reported-by: Eric Wustrow Reported-by: Nadia Heninger Reported-by: Zakir Durumeric Reported-by: J. Alex Halderman . Signed-off-by: Linus Torvalds Signed-off-by: "Theodore Ts'o" Cc: stable@vger.kernel.org --- kernel/irq/handle.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c index bdb180325551..131ca176b497 100644 --- a/kernel/irq/handle.c +++ b/kernel/irq/handle.c @@ -133,7 +133,7 @@ irqreturn_t handle_irq_event_percpu(struct irq_desc *desc, struct irqaction *action) { irqreturn_t retval = IRQ_NONE; - unsigned int random = 0, irq = desc->irq_data.irq; + unsigned int flags = 0, irq = desc->irq_data.irq; do { irqreturn_t res; @@ -161,7 +161,7 @@ handle_irq_event_percpu(struct irq_desc *desc, struct irqaction *action) /* Fall through to add to randomness */ case IRQ_HANDLED: - random |= action->flags; + flags |= action->flags; break; default: @@ -172,8 +172,7 @@ handle_irq_event_percpu(struct irq_desc *desc, struct irqaction *action) action = action->next; } while (action); - if (random & IRQF_SAMPLE_RANDOM) - add_interrupt_randomness(irq); + add_interrupt_randomness(irq, flags); if (!noirqdebug) note_interrupt(irq, desc, retval); -- cgit v1.2.3 From c5857ccf293968348e5eb4ebedc68074de3dcda6 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Sat, 14 Jul 2012 20:27:52 -0400 Subject: random: remove rand_initialize_irq() With the new interrupt sampling system, we are no longer using the timer_rand_state structure in the irq descriptor, so we can stop initializing it now. [ Merged in fixes from Sedat to find some last missing references to rand_initialize_irq() ] Signed-off-by: "Theodore Ts'o" Signed-off-by: Sedat Dilek --- arch/ia64/kernel/irq_ia64.c | 1 - drivers/char/random.c | 55 --------------------------------------------- drivers/mfd/ab3100-core.c | 3 --- include/linux/irqdesc.h | 1 - include/linux/random.h | 2 -- kernel/irq/manage.c | 17 -------------- 6 files changed, 79 deletions(-) (limited to 'kernel') diff --git a/arch/ia64/kernel/irq_ia64.c b/arch/ia64/kernel/irq_ia64.c index 5c3e0888265a..1034884b77da 100644 --- a/arch/ia64/kernel/irq_ia64.c +++ b/arch/ia64/kernel/irq_ia64.c @@ -23,7 +23,6 @@ #include #include #include -#include /* for rand_initialize_irq() */ #include #include #include diff --git a/drivers/char/random.c b/drivers/char/random.c index e3180852ec85..9793b40f5754 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -634,43 +634,6 @@ struct timer_rand_state { unsigned dont_count_entropy:1; }; -#ifndef CONFIG_GENERIC_HARDIRQS - -static struct timer_rand_state *irq_timer_state[NR_IRQS]; - -static struct timer_rand_state *get_timer_rand_state(unsigned int irq) -{ - return irq_timer_state[irq]; -} - -static void set_timer_rand_state(unsigned int irq, - struct timer_rand_state *state) -{ - irq_timer_state[irq] = state; -} - -#else - -static struct timer_rand_state *get_timer_rand_state(unsigned int irq) -{ - struct irq_desc *desc; - - desc = irq_to_desc(irq); - - return desc->timer_rand_state; -} - -static void set_timer_rand_state(unsigned int irq, - struct timer_rand_state *state) -{ - struct irq_desc *desc; - - desc = irq_to_desc(irq); - - desc->timer_rand_state = state; -} -#endif - /* * Add device- or boot-specific data to the input and nonblocking * pools to help initialize them to unique values. @@ -1133,24 +1096,6 @@ static int rand_initialize(void) } module_init(rand_initialize); -void rand_initialize_irq(int irq) -{ - struct timer_rand_state *state; - - state = get_timer_rand_state(irq); - - if (state) - return; - - /* - * If kzalloc returns null, we just won't use that entropy - * source. - */ - state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); - if (state) - set_timer_rand_state(irq, state); -} - #ifdef CONFIG_BLOCK void rand_initialize_disk(struct gendisk *disk) { diff --git a/drivers/mfd/ab3100-core.c b/drivers/mfd/ab3100-core.c index 9522d6bda4f7..1287645b984d 100644 --- a/drivers/mfd/ab3100-core.c +++ b/drivers/mfd/ab3100-core.c @@ -931,9 +931,6 @@ static int __devinit ab3100_probe(struct i2c_client *client, err = request_threaded_irq(client->irq, NULL, ab3100_irq_handler, IRQF_ONESHOT, "ab3100-core", ab3100); - /* This real unpredictable IRQ is of course sampled for entropy */ - rand_initialize_irq(client->irq); - if (err) goto exit_no_irq; diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h index f1e2527006bd..9a323d12de1c 100644 --- a/include/linux/irqdesc.h +++ b/include/linux/irqdesc.h @@ -39,7 +39,6 @@ struct module; */ struct irq_desc { struct irq_data irq_data; - struct timer_rand_state *timer_rand_state; unsigned int __percpu *kstat_irqs; irq_flow_handler_t handle_irq; #ifdef CONFIG_IRQ_PREFLOW_FASTEOI diff --git a/include/linux/random.h b/include/linux/random.h index 29e217a7e6d0..ac621ce886ca 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -48,8 +48,6 @@ struct rnd_state { #ifdef __KERNEL__ -extern void rand_initialize_irq(int irq); - extern void add_device_randomness(const void *, unsigned int); extern void add_input_randomness(unsigned int type, unsigned int code, unsigned int value); diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 8c548232ba39..5e42eb119677 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -893,22 +893,6 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) return -ENOSYS; if (!try_module_get(desc->owner)) return -ENODEV; - /* - * Some drivers like serial.c use request_irq() heavily, - * so we have to be careful not to interfere with a - * running system. - */ - if (new->flags & IRQF_SAMPLE_RANDOM) { - /* - * This function might sleep, we want to call it first, - * outside of the atomic block. - * Yes, this might clear the entropy pool if the wrong - * driver is attempted to be loaded, without actually - * installing a new handler, but is this really a problem, - * only the sysadmin is able to do this. - */ - rand_initialize_irq(irq); - } /* * Check whether the interrupt nests into another interrupt @@ -1354,7 +1338,6 @@ EXPORT_SYMBOL(free_irq); * Flags: * * IRQF_SHARED Interrupt is shared - * IRQF_SAMPLE_RANDOM The interrupt can be used for entropy * IRQF_TRIGGER_* Specify active edge(s) or level * */ -- cgit v1.2.3