diff options
Diffstat (limited to 'drivers/char')
-rw-r--r-- | drivers/char/random.c | 54 |
1 files changed, 31 insertions, 23 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index cd9a6211dca..35487e8ded5 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"); |