diff options
Diffstat (limited to 'drivers/char/random.c')
| -rw-r--r-- | drivers/char/random.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index 72a4fcb1774..d4ddeba5668 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -128,6 +128,7 @@ * void add_input_randomness(unsigned int type, unsigned int code, * unsigned int value); * void add_interrupt_randomness(int irq); + * void add_disk_randomness(struct gendisk *disk); * * add_input_randomness() uses the input layer interrupt timing, as well as * the event type information from the hardware. @@ -136,9 +137,15 @@ * inputs to the entropy pool. Note that not all interrupts are good * sources of randomness! For example, the timer interrupts is not a * good choice, because the periodicity of the interrupts is too - * regular, and hence predictable to an attacker. Disk interrupts are - * a better measure, since the timing of the disk interrupts are more - * unpredictable. + * regular, and hence predictable to an attacker. Network Interface + * Controller interrupts are a better measure, since the timing of the + * NIC interrupts are more unpredictable. + * + * add_disk_randomness() uses what amounts to the seek time of block + * layer request events, on a per-disk_devt basis, as input to the + * entropy pool. Note that high-speed solid state drives with very low + * seek times do not make for good sources of entropy, as their seek + * times are usually fairly consistent. * * All of these routines try to estimate how many bits of randomness a * particular randomness source. They do this by keeping track of the @@ -725,7 +732,7 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf, size_t nbytes, int min, int rsvd); /* - * This utility inline function is responsible for transfering entropy + * This utility inline function is responsible for transferring entropy * from the primary pool to the secondary extraction pool. We make * sure we pull enough for a 'catastrophic reseed'. */ |