user/sven/linux.git/include/linux/random.h, branch v3.16.3

random: Add arch_has_random[_seed]()

2014-03-20T02:24:08Z

Add predicate functions for having arch_get_random[_seed]*(). The only current use is to avoid the loop in arch_random_refill() when arch_get_random_seed_long() is unavailable. Signed-off-by: H. Peter Anvin Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Signed-off-by: Theodore Ts'o

x86, random: Enable the RDSEED instruction

2014-03-20T02:22:06Z

Upcoming Intel silicon adds a new RDSEED instruction, which is similar to RDRAND but provides a stronger guarantee: unlike RDRAND, RDSEED will always reseed the PRNG from the true random number source between each read. Thus, the output of RDSEED is guaranteed to be 100% entropic, unlike RDRAND which is only architecturally guaranteed to be 1/512 entropic (although in practice is much more.) The RDSEED instruction takes the same time to execute as RDRAND, but RDSEED unlike RDRAND can legitimately return failure (CF=0) due to entropy exhaustion if too many threads on too many cores are hammering the RDSEED instruction at the same time. Therefore, we have to be more conservative and only use it in places where we can tolerate failures. This patch introduces the primitives arch_get_random_seed_{int,long}() but does not use it yet. Signed-off-by: H. Peter Anvin Reviewed-by: Ingo Molnar Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Signed-off-by: Theodore Ts'o

random32: add prandom_u32_max and convert open coded users

2014-01-22T07:17:20Z

Many functions have open coded a function that returns a random number in range [0,N-1]. Under the assumption that we have a PRNG such as taus113 with being well distributed in [0, ~0U] space, we can implement such a function as uword t = (n*m')>>32, where m' is a random number obtained from PRNG, n the right open interval border and t our resulting random number, with n,m',t in u32 universe. Lets go with Joe and simply call it prandom_u32_max(), although technically we have an right open interval endpoint, but that we have documented. Other users can further be migrated to the new prandom_u32_max() function later on; for now, we need to make sure to migrate reciprocal_divide() users for the reciprocal_divide() follow-up fixup since their function signatures are going to change. Joint work with Hannes Frederic Sowa. Cc: Jakub Zawadzki Cc: Eric Dumazet Cc: linux-kernel@vger.kernel.org Signed-off-by: Hannes Frederic Sowa Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller

random32: upgrade taus88 generator to taus113 from errata paper

2013-11-11T19:32:15Z

Since we use prandom*() functions quite often in networking code i.e. in UDP port selection, netfilter code, etc, upgrade the PRNG from Pierre L'Ecuyer's original paper "Maximally Equidistributed Combined Tausworthe Generators", Mathematics of Computation, 65, 213 (1996), 203--213 to the version published in his errata paper [1]. The Tausworthe generator is a maximally-equidistributed generator, that is fast and has good statistical properties [1]. The version presented there upgrades the 3 state LFSR to a 4 state LFSR with increased periodicity from about 2^88 to 2^113. The algorithm is presented in [1] by the very same author who also designed the original algorithm in [2]. Also, by increasing the state, we make it a bit harder for attackers to "guess" the PRNGs internal state. See also discussion in [3]. Now, as we use this sort of weak initialization discussed in [3] only between core_initcall() until late_initcall() time [*] for prandom32*() users, namely in prandom_init(), it is less relevant from late_initcall() onwards as we overwrite seeds through prandom_reseed() anyways with a seed source of higher entropy, that is, get_random_bytes(). In other words, a exhaustive keysearch of 96 bit would be needed. Now, with the help of this patch, this state-search increases further to 128 bit. Initialization needs to make sure that s1 > 1, s2 > 7, s3 > 15, s4 > 127. taus88 and taus113 algorithm is also part of GSL. I added a test case in the next patch to verify internal behaviour of this patch with GSL and ran tests with the dieharder 3.31.1 RNG test suite: $ dieharder -g 052 -a -m 10 -s 1 -S 4137730333 #taus88 $ dieharder -g 054 -a -m 10 -s 1 -S 4137730333 #taus113 With this seed configuration, in order to compare both, we get the following differences: algorithm taus88 taus113 rands/second [**] 1.61e+08 1.37e+08 sts_serial(4, 1st run) WEAK PASSED sts_serial(9, 2nd run) WEAK PASSED rgb_lagged_sum(31) WEAK PASSED We took out diehard_sums test as according to the authors it is considered broken and unusable [4]. Despite that and the slight decrease in performance (which is acceptable), taus113 here passes all 113 tests (only rgb_minimum_distance_5 in WEAK, the rest PASSED). In general, taus/taus113 is considered "very good" by the authors of dieharder [5]. The papers [1][2] states a single warm-up step is sufficient by running quicktaus once on each state to ensure proper initialization of ~s_{0}: Our selection of (s) according to Table 1 of [1] row 1 holds the condition L - k <= r - s, that is, (32 32 32 32) - (31 29 28 25) <= (25 27 15 22) - (18 2 7 13) with r = k - q and q = (6 2 13 3) as also stated by the paper. So according to [2] we are safe with one round of quicktaus for initialization. However we decided to include the warm-up phase of the PRNG as done in GSL in every case as a safety net. We also use the warm up phase to make the output of the RNG easier to verify by the GSL output. In prandom_init(), we also mix random_get_entropy() into it, just like drivers/char/random.c does it, jiffies ^ random_get_entropy(). random-get_entropy() is get_cycles(). xor is entropy preserving so it is fine if it is not implemented by some architectures. Note, this PRNG is *not* used for cryptography in the kernel, but rather as a fast PRNG for various randomizations i.e. in the networking code, or elsewhere for debugging purposes, for example. [*]: In order to generate some "sort of pseduo-randomness", since get_random_bytes() is not yet available for us, we use jiffies and initialize states s1 - s3 with a simple linear congruential generator (LCG), that is x <- x * 69069; and derive s2, s3, from the 32bit initialization from s1. So the above quote from [3] accounts only for the time from core to late initcall, not afterwards. [**] Single threaded run on MacBook Air w/ Intel Core i5-3317U [1] http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps [2] http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps [3] http://thread.gmane.org/gmane.comp.encryption.general/12103/ [4] http://code.google.com/p/dieharder/source/browse/trunk/libdieharder/diehard_sums.c?spec=svn490&r=490#20 [5] http://www.phy.duke.edu/~rgb/General/dieharder.php Joint work with Hannes Frederic Sowa. Cc: Florian Weimer Cc: Theodore Ts'o Signed-off-by: Daniel Borkmann Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller

random32: move rnd_state to linux/random.h

2013-11-11T19:32:14Z

struct rnd_state got mistakenly pulled into uapi header. It is not used anywhere and does also not belong there! Commit 5960164fde ("lib/random32: export pseudo-random number generator for modules"), the last commit on rnd_state before it got moved to uapi, says: This patch moves the definition of struct rnd_state and the inline __seed() function to linux/random.h. It renames the static __random32() function to prandom32() and exports it for use in modules. Hence, the structure was moved from lib/random32.c to linux/random.h so that it can be used within modules (FCoE-related code in this case), but not from user space. However, it seems to have been mistakenly moved to uapi header through the uapi script. Since no-one should make use of it from the linux headers, move the structure back to the kernel for internal use, so that it can be modified on demand. Joint work with Hannes Frederic Sowa. Cc: Joe Eykholt Signed-off-by: Daniel Borkmann Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller

random32: add prandom_reseed_late() and call when nonblocking pool becomes initialized

2013-11-11T19:32:14Z

The Tausworthe PRNG is initialized at late_initcall time. At that time the entropy pool serving get_random_bytes is not filled sufficiently. This patch adds an additional reseeding step as soon as the nonblocking pool gets marked as initialized. On some machines it might be possible that late_initcall gets called after the pool has been initialized. In this situation we won't reseed again. (A call to prandom_seed_late blocks later invocations of early reseed attempts.) Joint work with Daniel Borkmann. Cc: Eric Dumazet Cc: Theodore Ts'o Signed-off-by: Hannes Frederic Sowa Signed-off-by: Daniel Borkmann Acked-by: "Theodore Ts'o" Signed-off-by: David S. Miller

random32: fix off-by-one in seeding requirement

2013-11-11T19:32:14Z

For properly initialising the Tausworthe generator [1], we have a strict seeding requirement, that is, s1 > 1, s2 > 7, s3 > 15. Commit 697f8d0348 ("random32: seeding improvement") introduced a __seed() function that imposes boundary checks proposed by the errata paper [2] to properly ensure above conditions. However, we're off by one, as the function is implemented as: "return (x < m) ? x + m : x;", and called with __seed(X, 1), __seed(X, 7), __seed(X, 15). Thus, an unwanted seed of 1, 7, 15 would be possible, whereas the lower boundary should actually be of at least 2, 8, 16, just as GSL does. Fix this, as otherwise an initialization with an unwanted seed could have the effect that Tausworthe's PRNG properties cannot not be ensured. Note that this PRNG is *not* used for cryptography in the kernel. [1] http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps [2] http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps Joint work with Hannes Frederic Sowa. Fixes: 697f8d0348a6 ("random32: seeding improvement") Cc: Stephen Hemminger Cc: Florian Weimer Cc: Theodore Ts'o Signed-off-by: Daniel Borkmann Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller

random: run random_int_secret_init() run after all late_initcalls

2013-09-23T10:35:06Z

The some platforms (e.g., ARM) initializes their clocks as late_initcalls for some unknown reason. So make sure random_int_secret_init() is run after all of the late_initcalls are run. Cc: stable@vger.kernel.org Signed-off-by: "Theodore Ts'o"

remove unused random32() and srandom32()

2013-05-08T01:38:27Z

After finishing a naming transition, remove unused backward compatibility wrapper macros Signed-off-by: Akinobu Mita Cc: "Theodore Ts'o" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

soreuseport: infrastructure

2013-01-23T18:44:00Z

Definitions and macros for implementing soreusport. Signed-off-by: Tom Herbert Signed-off-by: David S. Miller