linux-toradex.git/drivers/char/random.c, branch v4.17

random: rate limit unseeded randomness warnings

2018-04-25T06:41:39+00:00

On systems without sufficient boot randomness, no point spamming dmesg.

Signed-off-by: Theodore Ts'o 
Cc: stable@vger.kernel.org

random: fix possible sleeping allocation from irq context

2018-04-24T16:00:08+00:00

We can do a sleeping allocation from an irq context when CONFIG_NUMA
is enabled.  Fix this by initializing the NUMA crng instances in a
workqueue.

Reported-by: Tetsuo Handa 
Reported-by: syzbot+9de458f6a5e713ee8c1a@syzkaller.appspotmail.com
Fixes: 8ef35c866f8862df ("random: set up the NUMA crng instances...")
Cc: stable@vger.kernel.org
Signed-off-by: Theodore Ts'o

random: add new ioctl RNDRESEEDCRNG

2018-04-14T15:59:31+00:00

Add a new ioctl which forces the the crng to be reseeded.

Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org

random: crng_reseed() should lock the crng instance that it is modifying

2018-04-14T15:59:31+00:00

Reported-by: Jann Horn 
Fixes: 1e7f583af67b ("random: make /dev/urandom scalable for silly...")
Cc: stable@kernel.org # 4.8+
Signed-off-by: Theodore Ts'o 
Reviewed-by: Jann Horn

random: set up the NUMA crng instances after the CRNG is fully initialized

2018-04-14T15:59:19+00:00

Until the primary_crng is fully initialized, don't initialize the NUMA
crng nodes.  Otherwise users of /dev/urandom on NUMA systems before
the CRNG is fully initialized can get very bad quality randomness.  Of
course everyone should move to getrandom(2) where this won't be an
issue, but there's a lot of legacy code out there.  This related to
CVE-2018-1108.

Reported-by: Jann Horn 
Fixes: 1e7f583af67b ("random: make /dev/urandom scalable for silly...")
Cc: stable@kernel.org # 4.8+
Signed-off-by: Theodore Ts'o

random: use a different mixing algorithm for add_device_randomness()

2018-04-14T15:59:09+00:00

add_device_randomness() use of crng_fast_load() was highly
problematic.  Some callers of add_device_randomness() can pass in a
large amount of static information.  This would immediately promote
the crng_init state from 0 to 1, without really doing much to
initialize the primary_crng's internal state with something even
vaguely unpredictable.

Since we don't have the speed constraints of add_interrupt_randomness(),
we can do a better job mixing in the what unpredictability a device
driver or architecture maintainer might see fit to give us, and do it
in a way which does not bump the crng_init_cnt variable.

Also, since add_device_randomness() doesn't bump any entropy
accounting in crng_init state 0, mix the device randomness into the
input_pool entropy pool as well.  This is related to CVE-2018-1108.

Reported-by: Jann Horn 
Fixes: ee7998c50c26 ("random: do not ignore early device randomness")
Cc: stable@kernel.org # 4.13+
Signed-off-by: Theodore Ts'o

random: fix crng_ready() test

2018-04-14T15:58:26+00:00

The crng_init variable has three states:

0: The CRNG is not initialized at all
1: The CRNG has a small amount of entropy, hopefully good enough for
   early-boot, non-cryptographical use cases
2: The CRNG is fully initialized and we are sure it is safe for
   cryptographic use cases.

The crng_ready() function should only return true once we are in the
last state.  This addresses CVE-2018-1108.

Reported-by: Jann Horn 
Fixes: e192be9d9a30 ("random: replace non-blocking pool...")
Cc: stable@kernel.org # 4.8+
Signed-off-by: Theodore Ts'o 
Reviewed-by: Jann Horn

drivers/char/random.c: remove unused dont_count_entropy

2018-03-01T00:03:19+00:00

Ever since "random: kill dead extract_state struct" [1], the
dont_count_entropy member of struct timer_rand_state has been
effectively unused. Since it hasn't found a new use in 12 years, it's
probably safe to finally kill it.

[1] Pre-git, https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=c1c48e61c251f57e7a3f1bf11b3c462b2de9dcb5

Signed-off-by: Rasmus Villemoes 
Signed-off-by: Theodore Ts'o

random: optimize add_interrupt_randomness

2018-02-28T23:01:16+00:00

add_interrupt_randomess always wakes up
code blocking on /dev/random. This wake up is done
unconditionally. Unfortunately this means all interrupts
take the wait queue spinlock, which can be rather expensive
on large systems processing lots of interrupts.

We saw 1% cpu time spinning on this on a large macro workload
running on a large system.

I believe it's a recent regression (?)

Always check if there is a waiter on the wait queue
before waking up. This check can be done without
taking a spinlock.

1.06%         10460  [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
         |
         ---native_queued_spin_lock_slowpath
            |
             --0.57%--_raw_spin_lock_irqsave
                       |
                        --0.56%--__wake_up_common_lock
                                  credit_entropy_bits
                                  add_interrupt_randomness
                                  handle_irq_event_percpu
                                  handle_irq_event
                                  handle_edge_irq
                                  handle_irq
                                  do_IRQ
                                  common_interrupt

Signed-off-by: Andi Kleen 
Signed-off-by: Theodore Ts'o

random: use a tighter cap in credit_entropy_bits_safe()

2018-02-28T22:58:11+00:00

This fixes a harmless UBSAN where root could potentially end up
causing an overflow while bumping the entropy_total field (which is
ignored once the entropy pool has been initialized, and this generally
is completed during the boot sequence).

This is marginal for the stable kernel series, but it's a really
trivial patch, and it fixes UBSAN warning that might cause security
folks to get overly excited for no reason.

Signed-off-by: Theodore Ts'o 
Reported-by: Chen Feng 
Cc: stable@vger.kernel.org