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| author | Neil Horman <nhorman@tuxdriver.com> | 2009-06-18 15:50:21 +0400 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2009-06-18 15:50:21 +0400 |
| commit | 5b739ef8a4e8cf5201d21abff897e292c232477b (patch) | |
| tree | 6301126016ad869997b4ef31973999e16049dfeb /drivers/char/random.c | |
| parent | b6f34d44cb341ad32f08717d1a2c418e6053a031 (diff) | |
| download | linux-5b739ef8a4e8cf5201d21abff897e292c232477b.tar.xz | |
random: Add optional continuous repetition test to entropy store based rngs
FIPS-140 requires that all random number generators implement continuous self
tests in which each extracted block of data is compared against the last block
for repetition. The ansi_cprng implements such a test, but it would be nice if
the hw rng's did the same thing. Obviously its not something thats always
needed, but it seems like it would be a nice feature to have on occasion. I've
written the below patch which allows individual entropy stores to be flagged as
desiring a continuous test to be run on them as is extracted. By default this
option is off, but is enabled in the event that fips mode is selected during
bootup.
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'drivers/char/random.c')
| -rw-r--r-- | drivers/char/random.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index 8c7444857a4b..d8a9255e1a3f 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -240,6 +240,7 @@ #include <linux/spinlock.h> #include <linux/percpu.h> #include <linux/cryptohash.h> +#include <linux/fips.h> #ifdef CONFIG_GENERIC_HARDIRQS # include <linux/irq.h> @@ -413,6 +414,7 @@ struct entropy_store { unsigned add_ptr; int entropy_count; int input_rotate; + __u8 *last_data; }; static __u32 input_pool_data[INPUT_POOL_WORDS]; @@ -852,12 +854,21 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf, { ssize_t ret = 0, i; __u8 tmp[EXTRACT_SIZE]; + unsigned long flags; xfer_secondary_pool(r, nbytes); nbytes = account(r, nbytes, min, reserved); while (nbytes) { extract_buf(r, tmp); + + if (r->last_data) { + spin_lock_irqsave(&r->lock, flags); + if (!memcmp(tmp, r->last_data, EXTRACT_SIZE)) + panic("Hardware RNG duplicated output!\n"); + memcpy(r->last_data, tmp, EXTRACT_SIZE); + spin_unlock_irqrestore(&r->lock, flags); + } i = min_t(int, nbytes, EXTRACT_SIZE); memcpy(buf, tmp, i); nbytes -= i; @@ -940,6 +951,9 @@ static void init_std_data(struct entropy_store *r) now = ktime_get_real(); mix_pool_bytes(r, &now, sizeof(now)); mix_pool_bytes(r, utsname(), sizeof(*(utsname()))); + /* Enable continuous test in fips mode */ + if (fips_enabled) + r->last_data = kmalloc(EXTRACT_SIZE, GFP_KERNEL); } static int rand_initialize(void) |