From: Tony Luck <tony.luck@intel.com>
To: "Theodore Ts'o" <tytso@mit.edu>
Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
w@1wt.eu, ewust@umich.edu, zakir@umich.edu, greg@kroah.com,
mpm@selenic.com, nadiah@cs.ucsd.edu, jhalderm@umich.edu,
tglx@linutronix.de, davem@davemloft.net,
"Theodore Ts'o" <tytso@mit.edu>
Subject: [PATCH] random: Add comment to random_initialize()
Date: Mon, 23 Jul 2012 09:47:57 -0700 [thread overview]
Message-ID: <b0ae8224c13a4fc2320a43192582d1f357453c5d.1343062864.git.tony.luck@intel.com> (raw)
In-Reply-To: <20120721020258.GA12898@thunk.org>
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>
---
Theodore Ts'o wrote:
> I agree. Want to send a revised patch with the comment, and I'll drop
> it into the random.git tree?
Additional patch rather than revised (since I'm touching different
subsystems: dmi and random).
drivers/char/random.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 9793b40..1a2dfa8 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1087,6 +1087,16 @@ static void init_std_data(struct entropy_store *r)
mix_pool_bytes(r, utsname(), sizeof(*(utsname())), NULL);
}
+/*
+ * Note that setup_arch() may call add_device_randomness()
+ * long before we get here. This allows seeding of the pools
+ * with some platform dependent data very early in the boot
+ * process. But it limits our options here. We must use
+ * statically allocated structures that already have all
+ * initializations complete at compile time. We should also
+ * take care not to overwrite the precious per platform data
+ * we were given.
+ */
static int rand_initialize(void)
{
init_std_data(&input_pool);
--
1.7.10.2.552.gaa3bb87
prev parent reply other threads:[~2012-07-23 17:10 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-05 18:12 [PATCH 00/10] /dev/random fixups Theodore Ts'o
2012-07-05 18:12 ` [PATCH 01/10] random: make 'add_interrupt_randomness()' do something sane Theodore Ts'o
2012-07-05 18:47 ` Matt Mackall
2012-07-05 18:52 ` Linus Torvalds
2012-07-05 21:39 ` Matt Mackall
2012-07-05 21:47 ` Linus Torvalds
2012-07-05 22:00 ` Theodore Ts'o
2012-07-05 22:21 ` Linus Torvalds
2012-07-05 22:31 ` Matt Mackall
2012-07-05 22:35 ` Linus Torvalds
2012-07-05 23:21 ` Theodore Ts'o
2012-07-06 2:59 ` Linus Torvalds
2012-07-06 13:01 ` Theodore Ts'o
2012-07-06 16:24 ` Linus Torvalds
2012-07-06 16:52 ` Theodore Ts'o
2012-07-09 19:15 ` Matt Mackall
2012-07-25 18:43 ` Thomas Gleixner
[not found] ` <CAGsuqq2MWuFnY7PMb_2ddBNNJr80xB_JW+Wryq3mhhmQuEojpg@mail.gmail.com>
2012-07-06 21:59 ` Theodore Ts'o
2012-07-05 18:12 ` [PATCH 02/10] random: use lockless techniques when mixing entropy pools Theodore Ts'o
2012-07-05 18:18 ` Linus Torvalds
2012-07-05 18:19 ` Greg KH
2012-07-05 23:09 ` Theodore Ts'o
2012-07-05 19:10 ` Matt Mackall
2012-07-05 19:47 ` Theodore Ts'o
2012-07-05 20:45 ` Matt Mackall
2012-07-05 18:12 ` [PATCH 03/10] random: create add_device_randomness() interface Theodore Ts'o
2012-07-05 18:12 ` [PATCH 04/10] usb: feed USB device information to the /dev/random driver Theodore Ts'o
2012-07-05 18:12 ` [PATCH 05/10] net: feed /dev/random with the MAC address when registering a device Theodore Ts'o
2012-07-05 18:12 ` [PATCH 06/10] random: use the arch-specific rng in xfer_secondary_pool Theodore Ts'o
2012-07-05 18:49 ` Linus Torvalds
2012-07-05 18:12 ` [PATCH 07/10] random: add new get_random_bytes_arch() function Theodore Ts'o
2012-07-05 18:35 ` Linus Torvalds
2012-07-05 19:50 ` Theodore Ts'o
2012-07-05 21:45 ` Matt Mackall
2012-07-25 3:37 ` H. Peter Anvin
2012-07-25 7:22 ` Ingo Molnar
2012-07-25 15:10 ` Theodore Ts'o
2012-07-25 15:19 ` H. Peter Anvin
2012-07-25 17:37 ` [PATCH] random: mix in architectural randomness in extract_buf() H. Peter Anvin
2012-07-25 23:50 ` Ben Hutchings
2012-07-26 0:32 ` H. Peter Anvin
2012-07-28 2:39 ` Theodore Ts'o
2012-07-28 2:48 ` H. Peter Anvin
2012-07-26 3:16 ` [PATCH 07/10] random: add new get_random_bytes_arch() function H. Peter Anvin
2012-07-26 3:24 ` H. Peter Anvin
2012-07-05 18:12 ` [PATCH 08/10] random: unify mix_pool_bytes() and mix_pool_bytes_entropy() Theodore Ts'o
2012-07-05 18:12 ` [PATCH 09/10] random: add tracepoints for easier debugging and verification Theodore Ts'o
2012-07-05 18:12 ` [PATCH 10/10] MAINTAINERS: Theodore Ts'o is taking over the random driver Theodore Ts'o
2012-07-06 11:40 ` [PATCH 00/10] /dev/random fixups Fengguang Wu
2012-07-06 12:44 ` Theodore Ts'o
2012-07-20 20:15 ` [PATCH] dmi: Feed DMI table to /dev/random driver Tony Luck
2012-07-20 21:03 ` Matt Mackall
2012-07-21 0:56 ` Theodore Ts'o
2012-07-21 1:19 ` Tony Luck
2012-07-21 2:02 ` Theodore Ts'o
2012-07-23 16:47 ` Tony Luck [this message]
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