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Subject[PATCH] (5/7) untrusted entropy sources
[correction: RML's SA_SAMPLE_RANDOM patch is safe after _this_ patch]

This makes irq and blkdev interrupts untrusted and does away with
their superfluous state initialization and tracking.

diff -ur a/arch/alpha/kernel/irq.c b/arch/alpha/kernel/irq.c
--- a/arch/alpha/kernel/irq.c 2002-08-17 00:30:02.000000000 -0500
+++ b/arch/alpha/kernel/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -166,17 +166,6 @@
* so we have to be careful not to interfere with a
* running system.
*/
- if (new->flags & SA_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);
- }

/*
* The following block of code has to be executed atomically
diff -ur a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
--- a/arch/arm/kernel/irq.c 2002-08-17 00:30:02.000000000 -0500
+++ b/arch/arm/kernel/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -458,17 +458,6 @@
* so we have to be careful not to interfere with a
* running system.
*/
- if (new->flags & SA_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);
- }

/*
* The following block of code has to be executed atomically
diff -ur a/arch/cris/kernel/irq.c b/arch/cris/kernel/irq.c
--- a/arch/cris/kernel/irq.c 2002-08-17 00:29:50.000000000 -0500
+++ b/arch/cris/kernel/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -315,9 +315,6 @@
shared = 1;
}

- if (new->flags & SA_SAMPLE_RANDOM)
- rand_initialize_irq(irq);
-
save_flags(flags);
cli();
*p = new;
diff -ur a/arch/i386/kernel/irq.c b/arch/i386/kernel/irq.c
--- a/arch/i386/kernel/irq.c 2002-08-17 00:29:58.000000000 -0500
+++ b/arch/i386/kernel/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -733,17 +733,6 @@
* so we have to be careful not to interfere with a
* running system.
*/
- if (new->flags & SA_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);
- }

/*
* The following block of code has to be executed atomically
diff -ur a/arch/ia64/kernel/irq.c b/arch/ia64/kernel/irq.c
--- a/arch/ia64/kernel/irq.c 2002-08-17 00:29:50.000000000 -0500
+++ b/arch/ia64/kernel/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -1016,17 +1016,6 @@
* so we have to be careful not to interfere with a
* running system.
*/
- if (new->flags & SA_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);
- }

if (new->flags & SA_PERCPU_IRQ) {
desc->status |= IRQ_PER_CPU;
diff -ur a/arch/ia64/kernel/irq_ia64.c b/arch/ia64/kernel/irq_ia64.c
--- a/arch/ia64/kernel/irq_ia64.c 2002-07-20 14:11:14.000000000 -0500
+++ b/arch/ia64/kernel/irq_ia64.c 2002-08-23 12:43:29.000000000 -0500
@@ -22,7 +22,6 @@
#include <linux/kernel_stat.h>
#include <linux/slab.h>
#include <linux/ptrace.h>
-#include <linux/random.h> /* for rand_initialize_irq() */
#include <linux/signal.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
diff -ur a/arch/mips/baget/irq.c b/arch/mips/baget/irq.c
--- a/arch/mips/baget/irq.c 2002-08-17 00:29:50.000000000 -0500
+++ b/arch/mips/baget/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -284,9 +284,6 @@
shared = 1;
}

- if (new->flags & SA_SAMPLE_RANDOM)
- rand_initialize_irq(irq);
-
save_and_cli(flags);
*p = new;
restore_flags(flags);
diff -ur a/arch/mips/dec/irq.c b/arch/mips/dec/irq.c
--- a/arch/mips/dec/irq.c 2002-08-17 00:29:50.000000000 -0500
+++ b/arch/mips/dec/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -181,8 +181,6 @@
} while (old);
shared = 1;
}
- if (new->flags & SA_SAMPLE_RANDOM)
- rand_initialize_irq(irq);

save_and_cli(flags);
*p = new;
diff -ur a/arch/mips/kernel/irq.c b/arch/mips/kernel/irq.c
--- a/arch/mips/kernel/irq.c 2002-08-17 00:29:50.000000000 -0500
+++ b/arch/mips/kernel/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -649,17 +649,6 @@
* so we have to be careful not to interfere with a
* running system.
*/
- if (new->flags & SA_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);
- }

/*
* The following block of code has to be executed atomically
diff -ur a/arch/mips/kernel/old-irq.c b/arch/mips/kernel/old-irq.c
--- a/arch/mips/kernel/old-irq.c 2002-08-17 00:29:50.000000000 -0500
+++ b/arch/mips/kernel/old-irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -263,9 +263,6 @@
shared = 1;
}

- if (new->flags & SA_SAMPLE_RANDOM)
- rand_initialize_irq(irq);
-
save_and_cli(flags);
*p = new;

diff -ur a/arch/mips/philips/nino/irq.c b/arch/mips/philips/nino/irq.c
--- a/arch/mips/philips/nino/irq.c 2002-08-17 00:29:50.000000000 -0500
+++ b/arch/mips/philips/nino/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -227,8 +227,6 @@
} while (old);
shared = 1;
}
- if (new->flags & SA_SAMPLE_RANDOM)
- rand_initialize_irq(irq);

save_and_cli(flags);
*p = new;
diff -ur a/arch/mips64/mips-boards/malta/malta_int.c b/arch/mips64/mips-boards/malta/malta_int.c
--- a/arch/mips64/mips-boards/malta/malta_int.c 2002-07-20 14:11:29.000000000 -0500
+++ b/arch/mips64/mips-boards/malta/malta_int.c 2002-08-23 12:43:29.000000000 -0500
@@ -247,9 +247,6 @@
shared = 1;
}

- if (new->flags & SA_SAMPLE_RANDOM)
- rand_initialize_irq(irq);
-
*p = new;
if (!shared)
enable_irq(irq);
diff -ur a/arch/mips64/sgi-ip27/ip27-irq.c b/arch/mips64/sgi-ip27/ip27-irq.c
--- a/arch/mips64/sgi-ip27/ip27-irq.c 2002-08-17 00:29:50.000000000 -0500
+++ b/arch/mips64/sgi-ip27/ip27-irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -339,8 +339,6 @@
printk("IRQ array overflow %d\n", irq);
while(1);
}
- if (new->flags & SA_SAMPLE_RANDOM)
- rand_initialize_irq(irq);

save_and_cli(flags);
p = irq_action + irq;
diff -ur a/arch/ppc/kernel/irq.c b/arch/ppc/kernel/irq.c
--- a/arch/ppc/kernel/irq.c 2002-08-17 00:30:02.000000000 -0500
+++ b/arch/ppc/kernel/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -133,17 +133,6 @@
* so we have to be careful not to interfere with a
* running system.
*/
- if (new->flags & SA_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);
- }

/*
* The following block of code has to be executed atomically
diff -ur a/arch/ppc64/kernel/irq.c b/arch/ppc64/kernel/irq.c
--- a/arch/ppc64/kernel/irq.c 2002-08-17 00:29:50.000000000 -0500
+++ b/arch/ppc64/kernel/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -120,17 +120,6 @@
* so we have to be careful not to interfere with a
* running system.
*/
- if (new->flags & SA_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);
- }

/*
* The following block of code has to be executed atomically
diff -ur a/arch/sh/kernel/irq.c b/arch/sh/kernel/irq.c
--- a/arch/sh/kernel/irq.c 2002-08-17 00:29:50.000000000 -0500
+++ b/arch/sh/kernel/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -499,17 +499,6 @@
* so we have to be careful not to interfere with a
* running system.
*/
- if (new->flags & SA_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);
- }

/*
* The following block of code has to be executed atomically
diff -ur a/arch/sparc64/kernel/irq.c b/arch/sparc64/kernel/irq.c
--- a/arch/sparc64/kernel/irq.c 2002-08-17 00:30:02.000000000 -0500
+++ b/arch/sparc64/kernel/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -316,20 +316,6 @@
if (!handler)
return -EINVAL;

- if ((bucket != &pil0_dummy_bucket) && (irqflags & SA_SAMPLE_RANDOM)) {
- /*
- * This function might sleep, we want to call it first,
- * outside of the atomic block. In SA_STATIC_ALLOC case,
- * random driver's kmalloc will fail, but it is safe.
- * If already initialized, random driver will not reinit.
- * 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);
- }
-
spin_lock_irqsave(&irq_action_lock, flags);

action = *(bucket->pil + irq_action);
diff -ur a/arch/x86_64/kernel/irq.c b/arch/x86_64/kernel/irq.c
--- a/arch/x86_64/kernel/irq.c 2002-08-17 00:29:50.000000000 -0500
+++ b/arch/x86_64/kernel/irq.c 2002-08-23 12:43:29.000000000 -0500
@@ -986,17 +986,6 @@
* so we have to be careful not to interfere with a
* running system.
*/
- if (new->flags & SA_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);
- }

/*
* The following block of code has to be executed atomically
diff -ur a/drivers/char/random.c b/drivers/char/random.c
--- a/drivers/char/random.c 2002-08-23 12:43:27.000000000 -0500
+++ b/drivers/char/random.c 2002-08-23 12:43:29.000000000 -0500
@@ -686,14 +686,11 @@
struct timer_rand_state {
__u32 last_time;
__s32 last_delta,last_delta2;
- int dont_count_entropy:1;
};

static struct timer_rand_state keyboard_timer_state;
static struct timer_rand_state mouse_timer_state;
static struct timer_rand_state extract_timer_state;
-static struct timer_rand_state *irq_timer_state[NR_IRQS];
-static struct timer_rand_state *blkdev_timer_state[MAX_BLKDEV];
static int trust_break=50, trust_pct=0, trust_min=0, trust_max=100;

/*
@@ -731,7 +728,7 @@
* We take into account the first, second and third-order deltas
* in order to make our estimate.
*/
- if (!state->dont_count_entropy) {
+ if (state) {
delta = time - state->last_time;
state->last_time = time;

@@ -793,24 +790,12 @@

void add_interrupt_randomness(int irq)
{
- if (irq >= NR_IRQS || irq_timer_state[irq] == 0)
- return;
-
- add_timer_randomness(irq_timer_state[irq], 0x100+irq);
+ add_timer_randomness(0, irq);
}

void add_blkdev_randomness(int major)
{
- if (major >= MAX_BLKDEV)
- return;
-
- if (blkdev_timer_state[major] == 0) {
- rand_initialize_blkdev(major, GFP_ATOMIC);
- if (blkdev_timer_state[major] == 0)
- return;
- }
-
- add_timer_randomness(blkdev_timer_state[major], 0x200+major);
+ add_timer_randomness(0, 0x200+major);
}

/******************************************************************
@@ -1418,53 +1403,10 @@
#ifdef CONFIG_SYSCTL
sysctl_init_random(random_state);
#endif
- for (i = 0; i < NR_IRQS; i++)
- irq_timer_state[i] = NULL;
- for (i = 0; i < MAX_BLKDEV; i++)
- blkdev_timer_state[i] = NULL;
memset(&keyboard_timer_state, 0, sizeof(struct timer_rand_state));
memset(&mouse_timer_state, 0, sizeof(struct timer_rand_state));
- memset(&extract_timer_state, 0, sizeof(struct timer_rand_state));
- extract_timer_state.dont_count_entropy = 1;
-}
-
-void rand_initialize_irq(int irq)
-{
- struct timer_rand_state *state;
-
- if (irq >= NR_IRQS || irq_timer_state[irq])
- return;
-
- /*
- * If kmalloc returns null, we just won't use that entropy
- * source.
- */
- state = kmalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
- if (state) {
- memset(state, 0, sizeof(struct timer_rand_state));
- irq_timer_state[irq] = state;
- }
-}
-
-void rand_initialize_blkdev(int major, int mode)
-{
- struct timer_rand_state *state;
-
- if (major >= MAX_BLKDEV || blkdev_timer_state[major])
- return;
-
- /*
- * If kmalloc returns null, we just won't use that entropy
- * source.
- */
- state = kmalloc(sizeof(struct timer_rand_state), mode);
- if (state) {
- memset(state, 0, sizeof(struct timer_rand_state));
- blkdev_timer_state[major] = state;
- }
}

-
static ssize_t
random_read(struct file * file, char * buf, size_t nbytes, loff_t *ppos)
{
diff -ur a/include/linux/random.h b/include/linux/random.h
--- a/include/linux/random.h 2002-08-23 12:43:22.000000000 -0500
+++ b/include/linux/random.h 2002-08-23 12:43:29.000000000 -0500
@@ -43,8 +43,6 @@
#ifdef __KERNEL__

extern void rand_initialize(void);
-extern void rand_initialize_irq(int irq);
-extern void rand_initialize_blkdev(int irq, int mode);

extern void batch_entropy_store(u32 val, int bits);


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