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<title>user/sven/linux.git/include/linux/random.h, branch v3.10.49</title>
<subtitle>Linux Kernel
</subtitle>
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<updated>2013-12-08T15:29:24Z</updated>
<entry>
<title>random32: fix off-by-one in seeding requirement</title>
<updated>2013-12-08T15:29:24Z</updated>
<author>
<name>Daniel Borkmann</name>
<email>dborkman@redhat.com</email>
</author>
<published>2013-11-11T11:20:32Z</published>
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<id>urn:sha1:e29507fecb79c00ae76f9ef626d282af8b1f4225</id>
<content type='text'>
[ Upstream commit 51c37a70aaa3f95773af560e6db3073520513912 ]

For properly initialising the Tausworthe generator [1], we have
a strict seeding requirement, that is, s1 &gt; 1, s2 &gt; 7, s3 &gt; 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 &lt; 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 &lt;stephen@networkplumber.org&gt;
Cc: Florian Weimer &lt;fweimer@redhat.com&gt;
Cc: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Daniel Borkmann &lt;dborkman@redhat.com&gt;
Signed-off-by: Hannes Frederic Sowa &lt;hannes@stressinduktion.org&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>random: run random_int_secret_init() run after all late_initcalls</title>
<updated>2013-10-18T14:45:44Z</updated>
<author>
<name>Theodore Ts'o</name>
<email>tytso@mit.edu</email>
</author>
<published>2013-09-10T14:52:35Z</published>
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<id>urn:sha1:b7a52f5111bc53ffbfff96330621cbde80df6ba4</id>
<content type='text'>
commit 47d06e532e95b71c0db3839ebdef3fe8812fca2c upstream.

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.

Signed-off-by: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>remove unused random32() and srandom32()</title>
<updated>2013-05-08T01:38:27Z</updated>
<author>
<name>Akinobu Mita</name>
<email>akinobu.mita@gmail.com</email>
</author>
<published>2013-05-07T23:18:17Z</published>
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<id>urn:sha1:22ea9c070350b824d6c3b65bce06ee7c6cc87b99</id>
<content type='text'>
After finishing a naming transition, remove unused backward
compatibility wrapper macros

Signed-off-by: Akinobu Mita &lt;akinobu.mita@gmail.com&gt;
Cc: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>soreuseport: infrastructure</title>
<updated>2013-01-23T18:44:00Z</updated>
<author>
<name>Tom Herbert</name>
<email>therbert@google.com</email>
</author>
<published>2013-01-22T09:49:50Z</published>
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<id>urn:sha1:055dc21a1d1d219608cd4baac7d0683fb2cbbe8a</id>
<content type='text'>
Definitions and macros for implementing soreusport.

Signed-off-by: Tom Herbert &lt;therbert@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
</entry>
<entry>
<title>prandom: introduce prandom_bytes() and prandom_bytes_state()</title>
<updated>2012-12-18T01:15:26Z</updated>
<author>
<name>Akinobu Mita</name>
<email>akinobu.mita@gmail.com</email>
</author>
<published>2012-12-18T00:04:25Z</published>
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<id>urn:sha1:6582c665d6b882dad8329e05749fbcf119f1ab88</id>
<content type='text'>
Add functions to get the requested number of pseudo-random bytes.

The difference from get_random_bytes() is that it generates pseudo-random
numbers by prandom_u32().  It doesn't consume the entropy pool, and the
sequence is reproducible if the same rnd_state is used.  So it is suitable
for generating random bytes for testing.

Signed-off-by: Akinobu Mita &lt;akinobu.mita@gmail.com&gt;
Cc: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
Cc: Artem Bityutskiy &lt;dedekind1@gmail.com&gt;
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: David Woodhouse &lt;dwmw2@infradead.org&gt;
Cc: Eilon Greenstein &lt;eilong@broadcom.com&gt;
Cc: David Laight &lt;david.laight@aculab.com&gt;
Cc: Michel Lespinasse &lt;walken@google.com&gt;
Cc: Robert Love &lt;robert.w.love@intel.com&gt;
Cc: Valdis Kletnieks &lt;valdis.kletnieks@vt.edu&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>random32: rename random32 to prandom</title>
<updated>2012-12-18T01:15:26Z</updated>
<author>
<name>Akinobu Mita</name>
<email>akinobu.mita@gmail.com</email>
</author>
<published>2012-12-18T00:04:23Z</published>
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<id>urn:sha1:496f2f93b1cc286f5a4f4f9acdc1e5314978683f</id>
<content type='text'>
This renames all random32 functions to have 'prandom_' prefix as follows:

  void prandom_seed(u32 seed);	/* rename from srandom32() */
  u32 prandom_u32(void);		/* rename from random32() */
  void prandom_seed_state(struct rnd_state *state, u64 seed);
  				/* rename from prandom32_seed() */
  u32 prandom_u32_state(struct rnd_state *state);
  				/* rename from prandom32() */

The purpose of this renaming is to prevent some kernel developers from
assuming that prandom32() and random32() might imply that only
prandom32() was the one using a pseudo-random number generator by
prandom32's "p", and the result may be a very embarassing security
exposure.  This concern was expressed by Theodore Ts'o.

And furthermore, I'm going to introduce new functions for getting the
requested number of pseudo-random bytes.  If I continue to use both
prandom32 and random32 prefixes for these functions, the confusion
is getting worse.

As a result of this renaming, "prandom_" is the common prefix for
pseudo-random number library.

Currently, srandom32() and random32() are preserved because it is
difficult to rename too many users at once.

Signed-off-by: Akinobu Mita &lt;akinobu.mita@gmail.com&gt;
Cc: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
Cc: Robert Love &lt;robert.w.love@intel.com&gt;
Cc: Michel Lespinasse &lt;walken@google.com&gt;
Cc: Valdis Kletnieks &lt;valdis.kletnieks@vt.edu&gt;
Cc: David Laight &lt;david.laight@aculab.com&gt;
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Artem Bityutskiy &lt;dedekind1@gmail.com&gt;
Cc: David Woodhouse &lt;dwmw2@infradead.org&gt;
Cc: Eilon Greenstein &lt;eilong@broadcom.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>UAPI: (Scripted) Disintegrate include/linux</title>
<updated>2012-10-13T09:46:48Z</updated>
<author>
<name>David Howells</name>
<email>dhowells@redhat.com</email>
</author>
<published>2012-10-13T09:46:48Z</published>
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<id>urn:sha1:607ca46e97a1b6594b29647d98a32d545c24bdff</id>
<content type='text'>
Signed-off-by: David Howells &lt;dhowells@redhat.com&gt;
Acked-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Acked-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Acked-by: Michael Kerrisk &lt;mtk.manpages@gmail.com&gt;
Acked-by: Paul E. McKenney &lt;paulmck@linux.vnet.ibm.com&gt;
Acked-by: Dave Jones &lt;davej@redhat.com&gt;
</content>
</entry>
<entry>
<title>random: remove rand_initialize_irq()</title>
<updated>2012-07-19T14:38:32Z</updated>
<author>
<name>Theodore Ts'o</name>
<email>tytso@mit.edu</email>
</author>
<published>2012-07-15T00:27:52Z</published>
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<id>urn:sha1:c5857ccf293968348e5eb4ebedc68074de3dcda6</id>
<content type='text'>
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" &lt;tytso@mit.edu&gt;
Signed-off-by: Sedat Dilek &lt;sedat.dilek@gmail.com&gt;
</content>
</entry>
<entry>
<title>random: add new get_random_bytes_arch() function</title>
<updated>2012-07-15T00:17:47Z</updated>
<author>
<name>Theodore Ts'o</name>
<email>tytso@mit.edu</email>
</author>
<published>2012-07-05T14:35:23Z</published>
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<id>urn:sha1:c2557a303ab6712bb6e09447df828c557c710ac9</id>
<content type='text'>
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" &lt;tytso@mit.edu&gt;
Cc: stable@vger.kernel.org
</content>
</entry>
<entry>
<title>random: create add_device_randomness() interface</title>
<updated>2012-07-15T00:17:44Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2012-07-04T15:16:01Z</published>
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<id>urn:sha1:a2080a67abe9e314f9e9c2cc3a4a176e8a8f8793</id>
<content type='text'>
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 &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
Cc: stable@vger.kernel.org
</content>
</entry>
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