random: push extra entropy to the output pools (6265e169) · Commits · 戴 / test

drivers/char/random.c

+86 −32

Original line number	Diff line number	Diff line
		@@ -255,6 +255,7 @@
		#include <linux/fips.h>
		#include <linux/ptrace.h>
		#include <linux/kmemcheck.h>
		#include <linux/workqueue.h>

		#ifdef CONFIG_GENERIC_HARDIRQS
		# include <linux/irq.h>
		@@ -302,7 +303,7 @@ static int random_read_wakeup_thresh = 64;
		* should wake up processes which are selecting or polling on write
		* access to /dev/random.
		*/
		static int random_write_wakeup_thresh = 128;
		static int random_write_wakeup_thresh = 28 * OUTPUT_POOL_WORDS;

		/*
		* The minimum number of seconds between urandom pool resending. We
		@@ -428,6 +429,7 @@ struct entropy_store {
		__u32 *pool;
		const char *name;
		struct entropy_store *pull;
		struct work_struct push_work;

		/* read-write data: */
		unsigned long last_pulled;
		@@ -442,6 +444,7 @@ struct entropy_store {
		__u8 last_data[EXTRACT_SIZE];
		};

		static void push_to_pool(struct work_struct *work);
		static __u32 input_pool_data[INPUT_POOL_WORDS];
		static __u32 blocking_pool_data[OUTPUT_POOL_WORDS];
		static __u32 nonblocking_pool_data[OUTPUT_POOL_WORDS];
		@@ -460,7 +463,9 @@ static struct entropy_store blocking_pool = {
		.limit = 1,
		.pull = &input_pool,
		.lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock),
		.pool = blocking_pool_data
		.pool = blocking_pool_data,
		.push_work = __WORK_INITIALIZER(blocking_pool.push_work,
		push_to_pool),
		};

		static struct entropy_store nonblocking_pool = {
		@@ -468,7 +473,9 @@ static struct entropy_store nonblocking_pool = {
		.name = "nonblocking",
		.pull = &input_pool,
		.lock = __SPIN_LOCK_UNLOCKED(nonblocking_pool.lock),
		.pool = nonblocking_pool_data
		.pool = nonblocking_pool_data,
		.push_work = __WORK_INITIALIZER(nonblocking_pool.push_work,
		push_to_pool),
		};

		static __u32 const twist_table[8] = {
		@@ -655,22 +662,49 @@ retry:
		if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
		goto retry;

		if (!r->initialized && nbits > 0) {
		r->entropy_total += nbits;
		if (r->entropy_total > 128)
		if (!r->initialized && nbits > 0) {
		if (r->entropy_total > 128) {
		r->initialized = 1;
		r->entropy_total = 0;
		}
		}

		trace_credit_entropy_bits(r->name, nbits,
		entropy_count >> ENTROPY_SHIFT,
		r->entropy_total, _RET_IP_);

		if (r == &input_pool) {
		int entropy_bytes = entropy_count >> ENTROPY_SHIFT;

		/* should we wake readers? */
		if (r == &input_pool &&
		(entropy_count >> ENTROPY_SHIFT) >= random_read_wakeup_thresh) {
		if (entropy_bytes >= random_read_wakeup_thresh) {
		wake_up_interruptible(&random_read_wait);
		kill_fasync(&fasync, SIGIO, POLL_IN);
		}
		/* If the input pool is getting full, send some
		* entropy to the two output pools, flipping back and
		* forth between them, until the output pools are 75%
		* full.
		*/
		if (entropy_bytes > random_write_wakeup_thresh &&
		r->initialized &&
		r->entropy_total >= 2*random_read_wakeup_thresh) {
		static struct entropy_store *last = &blocking_pool;
		struct entropy_store *other = &blocking_pool;

		if (last == &blocking_pool)
		other = &nonblocking_pool;
		if (other->entropy_count <=
		3 * other->poolinfo->poolfracbits / 4)
		last = other;
		if (last->entropy_count <=
		3 * last->poolinfo->poolfracbits / 4) {
		schedule_work(&last->push_work);
		r->entropy_total = 0;
		}
		}
		}
		}

		static void credit_entropy_bits_safe(struct entropy_store *r, int nbits)
		@@ -877,10 +911,9 @@ static ssize_t extract_entropy(struct entropy_store r, void buf,
		* from the primary pool to the secondary extraction pool. We make
		* sure we pull enough for a 'catastrophic reseed'.
		*/
		static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes);
		static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
		{
		__u32 tmp[OUTPUT_POOL_WORDS];

		if (r->limit == 0 && random_min_urandom_seed) {
		unsigned long now = jiffies;

		@@ -891,8 +924,15 @@ static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
		}
		if (r->pull &&
		r->entropy_count < (nbytes << (ENTROPY_SHIFT + 3)) &&
		r->entropy_count < r->poolinfo->poolfracbits) {
		/* If we're limited, always leave two wakeup worth's BITS */
		r->entropy_count < r->poolinfo->poolfracbits)
		_xfer_secondary_pool(r, nbytes);
		}

		static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
		{
		__u32 tmp[OUTPUT_POOL_WORDS];

		/* For /dev/random's pool, always leave two wakeup worth's BITS */
		int rsvd = r->limit ? 0 : random_read_wakeup_thresh/4;
		int bytes = nbytes;

		@@ -901,8 +941,7 @@ static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
		/* but never more than the buffer size */
		bytes = min_t(int, bytes, sizeof(tmp));

		DEBUG_ENT("going to reseed %s with %d bits "
		"(%zu of %d requested)\n",
		DEBUG_ENT("going to reseed %s with %d bits (%zu of %d requested)\n",
		r->name, bytes * 8, nbytes * 8,
		r->entropy_count >> ENTROPY_SHIFT);

		@@ -911,6 +950,21 @@ static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
		mix_pool_bytes(r, tmp, bytes, NULL);
		credit_entropy_bits(r, bytes*8);
		}

		/*
		* Used as a workqueue function so that when the input pool is getting
		* full, we can "spill over" some entropy to the output pools. That
		* way the output pools can store some of the excess entropy instead
		* of letting it go to waste.
		*/
		static void push_to_pool(struct work_struct *work)
		{
		struct entropy_store *r = container_of(work, struct entropy_store,
		push_work);
		BUG_ON(!r);
		_xfer_secondary_pool(r, random_read_wakeup_thresh/8);
		trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT,
		r->pull->entropy_count >> ENTROPY_SHIFT);
		}

		/*

include/trace/events/random.h

+22 −0

Original line number	Diff line number	Diff line
		@@ -87,6 +87,28 @@ TRACE_EVENT(credit_entropy_bits,
		(void *)__entry->IP)
		);

		TRACE_EVENT(push_to_pool,
		TP_PROTO(const char *pool_name, int pool_bits, int input_bits),

		TP_ARGS(pool_name, pool_bits, input_bits),

		TP_STRUCT__entry(
		__field( const char *, pool_name )
		__field( int, pool_bits )
		__field( int, input_bits )
		),

		TP_fast_assign(
		__entry->pool_name = pool_name;
		__entry->pool_bits = pool_bits;
		__entry->input_bits = input_bits;
		),

		TP_printk("%s: pool_bits %d input_pool_bits %d",
		__entry->pool_name, __entry->pool_bits,
		__entry->input_bits)
		);

		DECLARE_EVENT_CLASS(random__get_random_bytes,
		TP_PROTO(int nbytes, unsigned long IP),

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