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path: root/drivers/char/random.c
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Diffstat (limited to 'drivers/char/random.c')
-rw-r--r--drivers/char/random.c54
1 files changed, 31 insertions, 23 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index cd9a6211dcad..35487e8ded59 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -865,16 +865,24 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
if (r->entropy_count / 8 < min + reserved) {
nbytes = 0;
} else {
+ int entropy_count, orig;
+retry:
+ entropy_count = orig = ACCESS_ONCE(r->entropy_count);
/* If limited, never pull more than available */
- if (r->limit && nbytes + reserved >= r->entropy_count / 8)
- nbytes = r->entropy_count/8 - reserved;
-
- if (r->entropy_count / 8 >= nbytes + reserved)
- r->entropy_count -= nbytes*8;
- else
- r->entropy_count = reserved;
+ if (r->limit && nbytes + reserved >= entropy_count / 8)
+ nbytes = entropy_count/8 - reserved;
+
+ if (entropy_count / 8 >= nbytes + reserved) {
+ entropy_count -= nbytes*8;
+ if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
+ goto retry;
+ } else {
+ entropy_count = reserved;
+ if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
+ goto retry;
+ }
- if (r->entropy_count < random_write_wakeup_thresh)
+ if (entropy_count < random_write_wakeup_thresh)
wakeup_write = 1;
}
@@ -957,10 +965,23 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
{
ssize_t ret = 0, i;
__u8 tmp[EXTRACT_SIZE];
+ unsigned long flags;
/* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
- if (fips_enabled && !r->last_data_init)
- nbytes += EXTRACT_SIZE;
+ if (fips_enabled) {
+ spin_lock_irqsave(&r->lock, flags);
+ if (!r->last_data_init) {
+ r->last_data_init = true;
+ spin_unlock_irqrestore(&r->lock, flags);
+ trace_extract_entropy(r->name, EXTRACT_SIZE,
+ r->entropy_count, _RET_IP_);
+ xfer_secondary_pool(r, EXTRACT_SIZE);
+ extract_buf(r, tmp);
+ spin_lock_irqsave(&r->lock, flags);
+ memcpy(r->last_data, tmp, EXTRACT_SIZE);
+ }
+ spin_unlock_irqrestore(&r->lock, flags);
+ }
trace_extract_entropy(r->name, nbytes, r->entropy_count, _RET_IP_);
xfer_secondary_pool(r, nbytes);
@@ -970,19 +991,6 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
extract_buf(r, tmp);
if (fips_enabled) {
- unsigned long flags;
-
-
- /* prime last_data value if need be, per fips 140-2 */
- if (!r->last_data_init) {
- spin_lock_irqsave(&r->lock, flags);
- memcpy(r->last_data, tmp, EXTRACT_SIZE);
- r->last_data_init = true;
- nbytes -= EXTRACT_SIZE;
- spin_unlock_irqrestore(&r->lock, flags);
- extract_buf(r, tmp);
- }
-
spin_lock_irqsave(&r->lock, flags);
if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
panic("Hardware RNG duplicated output!\n");