random: create add_device_randomness() interface

commit a2080a67abe9e314f9e9c2cc3a4a176e8a8f8793 upstream.

Add a new interface, add_device_randomness() for adding data to the
random pool that is likely to differ between two devices (or possibly
even per boot).  This would be things like MAC addresses or serial
numbers, or the read-out of the RTC. This does *not* add any actual
entropy to the pool, but it initializes the pool to different values
for devices that might otherwise be identical and have very little
entropy available to them (particularly common in the embedded world).

[ Modified by tytso to mix in a timestamp, since there may be some
  variability caused by the time needed to detect/configure the hardware
  in question. ]

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Patrick Tjin <pattjin@google.com>
random: use the arch-specific rng in xfer_secondary_pool

commit e6d4947b12e8ad947add1032dd754803c6004824 upstream.

If the CPU supports a hardware random number generator, use it in
xfer_secondary_pool(), where it will significantly improve things and
where we can afford it.

Also, remove the use of the arch-specific rng in
add_timer_randomness(), since the call is significantly slower than
get_cycles(), and we're much better off using it in
xfer_secondary_pool() anyway.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Patrick Tjin <pattjin@google.com>
random: add new get_random_bytes_arch() function

commit c2557a303ab6712bb6e09447df828c557c710ac9 upstream.

Create a new function, get_random_bytes_arch() which will use the
architecture-specific hardware random number generator if it is
present.  Change get_random_bytes() to not use the HW RNG, even if it
is avaiable.

The reason for this is that the hw random number generator is fast (if
it is present), but it requires that we trust the hardware
manufacturer to have not put in a back door.  (For example, an
increasing counter encrypted by an AES key known to the NSA.)

It's unlikely that Intel (for example) was paid off by the US
Government to do this, but it's impossible for them to prove otherwise
  --- especially since Bull Mountain is documented to use AES as a
whitener.  Hence, the output of an evil, trojan-horse version of
RDRAND is statistically indistinguishable from an RDRAND implemented
to the specifications claimed by Intel.  Short of using a tunnelling
electronic microscope to reverse engineer an Ivy Bridge chip and
disassembling and analyzing the CPU microcode, there's no way for us
to tell for sure.

Since users of get_random_bytes() in the Linux kernel need to be able
to support hardware systems where the HW RNG is not present, most
time-sensitive users of this interface have already created their own
cryptographic RNG interface which uses get_random_bytes() as a seed.
So it's much better to use the HW RNG to improve the existing random
number generator, by mixing in any entropy returned by the HW RNG into
/dev/random's entropy pool, but to always _use_ /dev/random's entropy
pool.

This way we get almost of the benefits of the HW RNG without any
potential liabilities.  The only benefits we forgo is the
speed/performance enhancements --- and generic kernel code can't
depend on depend on get_random_bytes() having the speed of a HW RNG
anyway.

For those places that really want access to the arch-specific HW RNG,
if it is available, we provide get_random_bytes_arch().

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Patrick Tjin <pattjin@google.com>
random: remove rand_initialize_irq()

commit c5857ccf293968348e5eb4ebedc68074de3dcda6 upstream.

With the new interrupt sampling system, we are no longer using the
timer_rand_state structure in the irq descriptor, so we can stop
initializing it now.

[ Merged in fixes from Sedat to find some last missing references to
  rand_initialize_irq() ]

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Patrick Tjin <pattjin@google.com>

Conflicts:
	arch/ia64/kernel/irq_ia64.c
	drivers/mfd/ab3100-core.c
	kernel/irq/manage.c
random: fix up sparse warnings

Add extern and static declarations to suppress sparse warnings

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
random: add tracepoints for easier debugging and verification

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
random: Add comment to random_initialize()

Many platforms have per-machine instance data (serial numbers,
asset tags, etc.) squirreled away in areas that are accessed
during early system bringup. Mixing this data into the random
pools has a very high value in providing better random data,
so we should allow (and even encourage) architecture code to
call add_device_randomness() from the setup_arch() paths.

However, this limits our options for internal structure of
the random driver since random_initialize() is not called
until long after setup_arch().

Add a big fat comment to rand_initialize() spelling out
this requirement.

Suggested-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
random: mix in architectural randomness in extract_buf()

Mix in any architectural randomness in extract_buf() instead of
xfer_secondary_buf().  This allows us to mix in more architectural
randomness, and it also makes xfer_secondary_buf() faster, moving a
tiny bit of additional CPU overhead to process which is extracting the
randomness.

[ Commit description modified by tytso to remove an extended
  advertisement for the RDRAND instruction. ]

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: DJ Johnston <dj.johnston@intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
random: fix debug format strings

Fix the following warnings in formatting debug output:

drivers/char/random.c: In function ‘xfer_secondary_pool’:
drivers/char/random.c:827: warning: format ‘%d’ expects type ‘int’, but argument 7 has type ‘size_t’
drivers/char/random.c: In function ‘account’:
drivers/char/random.c:859: warning: format ‘%d’ expects type ‘int’, but argument 5 has type ‘size_t’
drivers/char/random.c:881: warning: format ‘%d’ expects type ‘int’, but argument 5 has type ‘size_t’
drivers/char/random.c: In function ‘random_read’:
drivers/char/random.c:1141: warning: format ‘%d’ expects type ‘int’, but argument 5 has type ‘ssize_t’
drivers/char/random.c:1145: warning: format ‘%d’ expects type ‘int’, but argument 5 has type ‘ssize_t’
drivers/char/random.c:1145: warning: format ‘%d’ expects type ‘int’, but argument 6 has type ‘long unsigned int’

by using '%zd' instead of '%d' to properly denote ssize_t/size_t conversion.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
random: prime last_data value per fips requirements

The value stored in last_data must be primed for FIPS 140-2 purposes. Upon
first use, either on system startup or after an RNDCLEARPOOL ioctl, we
need to take an initial random sample, store it internally in last_data,
then pass along the value after that to the requester, so that consistency
checks aren't being run against stale and possibly known data.

CC: Herbert Xu <herbert@gondor.apana.org.au>
CC: "David S. Miller" <davem@davemloft.net>
CC: Matt Mackall <mpm@selenic.com>
CC: linux-crypto@vger.kernel.org
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
random: make it possible to enable debugging without rebuild

The module parameter that turns debugging mode (which basically means
printing a few extra lines during runtime) is in '#if 0' block. Forcing
everyone who would like to see how entropy is behaving on his system to
rebuild seems to be a little bit too harsh.

If we were concerned about speed, we could potentially turn 'debug' into a
static key, but I don't think it's necessary.

Drop the '#if 0' block to allow using the 'debug' parameter without rebuilding.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>