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-rw-r--r--drivers/char/random.c118
-rw-r--r--include/trace/events/random.h22
2 files changed, 108 insertions, 32 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 6da3f250804c..84c576ec20e9 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -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] = {
@@ -655,21 +662,48 @@ retry:
if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
goto retry;
+ r->entropy_total += nbits;
if (!r->initialized && nbits > 0) {
- r->entropy_total += nbits;
- if (r->entropy_total > 128)
+ 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_);
- /* should we wake readers? */
- if (r == &input_pool &&
- (entropy_count >> ENTROPY_SHIFT) >= random_read_wakeup_thresh) {
- wake_up_interruptible(&random_read_wait);
- kill_fasync(&fasync, SIGIO, POLL_IN);
+ if (r == &input_pool) {
+ int entropy_bytes = entropy_count >> ENTROPY_SHIFT;
+
+ /* should we wake readers? */
+ 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;
+ }
+ }
}
}
@@ -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;
@@ -891,26 +924,47 @@ 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 */
- int rsvd = r->limit ? 0 : random_read_wakeup_thresh/4;
- int bytes = nbytes;
-
- /* pull at least as many as BYTES as wakeup BITS */
- bytes = max_t(int, bytes, random_read_wakeup_thresh / 8);
- /* 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",
- r->name, bytes * 8, nbytes * 8,
- r->entropy_count >> ENTROPY_SHIFT);
-
- bytes = extract_entropy(r->pull, tmp, bytes,
- random_read_wakeup_thresh / 8, rsvd);
- mix_pool_bytes(r, tmp, bytes, NULL);
- credit_entropy_bits(r, bytes*8);
- }
+ 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;
+
+ /* pull at least as many as BYTES as wakeup BITS */
+ bytes = max_t(int, bytes, random_read_wakeup_thresh / 8);
+ /* 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",
+ r->name, bytes * 8, nbytes * 8,
+ r->entropy_count >> ENTROPY_SHIFT);
+
+ bytes = extract_entropy(r->pull, tmp, bytes,
+ random_read_wakeup_thresh / 8, rsvd);
+ 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);
}
/*
diff --git a/include/trace/events/random.h b/include/trace/events/random.h
index 2ffcaec5860a..527b5dc1b416 100644
--- a/include/trace/events/random.h
+++ b/include/trace/events/random.h
@@ -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),
generated by cgit v1.2.3-55-g7522 (git 2.39.0) at 2024-06-27 13:21:04 +0200