2177 lines
62 KiB
C
2177 lines
62 KiB
C
/*
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* random.c -- A strong random number generator
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*
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* Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All
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* Rights Reserved.
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*
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* Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005
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*
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* Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All
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* rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, and the entire permission notice in its entirety,
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* including the disclaimer of warranties.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* ALTERNATIVELY, this product may be distributed under the terms of
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* the GNU General Public License, in which case the provisions of the GPL are
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* required INSTEAD OF the above restrictions. (This clause is
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* necessary due to a potential bad interaction between the GPL and
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* the restrictions contained in a BSD-style copyright.)
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
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* WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
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* USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*/
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/*
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* (now, with legal B.S. out of the way.....)
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*
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* This routine gathers environmental noise from device drivers, etc.,
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* and returns good random numbers, suitable for cryptographic use.
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* Besides the obvious cryptographic uses, these numbers are also good
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* for seeding TCP sequence numbers, and other places where it is
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* desirable to have numbers which are not only random, but hard to
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* predict by an attacker.
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*
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* Theory of operation
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* ===================
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*
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* Computers are very predictable devices. Hence it is extremely hard
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* to produce truly random numbers on a computer --- as opposed to
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* pseudo-random numbers, which can easily generated by using a
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* algorithm. Unfortunately, it is very easy for attackers to guess
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* the sequence of pseudo-random number generators, and for some
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* applications this is not acceptable. So instead, we must try to
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* gather "environmental noise" from the computer's environment, which
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* must be hard for outside attackers to observe, and use that to
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* generate random numbers. In a Unix environment, this is best done
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* from inside the kernel.
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*
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* Sources of randomness from the environment include inter-keyboard
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* timings, inter-interrupt timings from some interrupts, and other
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* events which are both (a) non-deterministic and (b) hard for an
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* outside observer to measure. Randomness from these sources are
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* added to an "entropy pool", which is mixed using a CRC-like function.
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* This is not cryptographically strong, but it is adequate assuming
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* the randomness is not chosen maliciously, and it is fast enough that
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* the overhead of doing it on every interrupt is very reasonable.
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* As random bytes are mixed into the entropy pool, the routines keep
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* an *estimate* of how many bits of randomness have been stored into
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* the random number generator's internal state.
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*
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* When random bytes are desired, they are obtained by taking the SHA
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* hash of the contents of the "entropy pool". The SHA hash avoids
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* exposing the internal state of the entropy pool. It is believed to
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* be computationally infeasible to derive any useful information
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* about the input of SHA from its output. Even if it is possible to
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* analyze SHA in some clever way, as long as the amount of data
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* returned from the generator is less than the inherent entropy in
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* the pool, the output data is totally unpredictable. For this
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* reason, the routine decreases its internal estimate of how many
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* bits of "true randomness" are contained in the entropy pool as it
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* outputs random numbers.
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*
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* If this estimate goes to zero, the routine can still generate
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* random numbers; however, an attacker may (at least in theory) be
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* able to infer the future output of the generator from prior
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* outputs. This requires successful cryptanalysis of SHA, which is
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* not believed to be feasible, but there is a remote possibility.
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* Nonetheless, these numbers should be useful for the vast majority
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* of purposes.
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*
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* Exported interfaces ---- output
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* ===============================
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*
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* There are three exported interfaces; the first is one designed to
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* be used from within the kernel:
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*
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* void get_random_bytes(void *buf, int nbytes);
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*
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* This interface will return the requested number of random bytes,
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* and place it in the requested buffer.
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*
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* The two other interfaces are two character devices /dev/random and
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* /dev/urandom. /dev/random is suitable for use when very high
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* quality randomness is desired (for example, for key generation or
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* one-time pads), as it will only return a maximum of the number of
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* bits of randomness (as estimated by the random number generator)
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* contained in the entropy pool.
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*
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* The /dev/urandom device does not have this limit, and will return
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* as many bytes as are requested. As more and more random bytes are
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* requested without giving time for the entropy pool to recharge,
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* this will result in random numbers that are merely cryptographically
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* strong. For many applications, however, this is acceptable.
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*
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* Exported interfaces ---- input
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* ==============================
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*
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* The current exported interfaces for gathering environmental noise
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* from the devices are:
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*
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* void add_device_randomness(const void *buf, unsigned int size);
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* void add_input_randomness(unsigned int type, unsigned int code,
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* unsigned int value);
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* void add_interrupt_randomness(int irq, int irq_flags);
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* void add_disk_randomness(struct gendisk *disk);
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*
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* add_device_randomness() is for adding data to the random pool that
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* is likely to differ between two devices (or possibly even per boot).
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* This would be things like MAC addresses or serial numbers, or the
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* read-out of the RTC. This does *not* add any actual entropy to the
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* pool, but it initializes the pool to different values for devices
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* that might otherwise be identical and have very little entropy
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* available to them (particularly common in the embedded world).
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*
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* add_input_randomness() uses the input layer interrupt timing, as well as
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* the event type information from the hardware.
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*
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* add_interrupt_randomness() uses the interrupt timing as random
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* inputs to the entropy pool. Using the cycle counters and the irq source
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* as inputs, it feeds the randomness roughly once a second.
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*
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* add_disk_randomness() uses what amounts to the seek time of block
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* layer request events, on a per-disk_devt basis, as input to the
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* entropy pool. Note that high-speed solid state drives with very low
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* seek times do not make for good sources of entropy, as their seek
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* times are usually fairly consistent.
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*
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* All of these routines try to estimate how many bits of randomness a
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* particular randomness source. They do this by keeping track of the
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* first and second order deltas of the event timings.
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*
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* Ensuring unpredictability at system startup
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* ============================================
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*
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* When any operating system starts up, it will go through a sequence
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* of actions that are fairly predictable by an adversary, especially
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* if the start-up does not involve interaction with a human operator.
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* This reduces the actual number of bits of unpredictability in the
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* entropy pool below the value in entropy_count. In order to
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* counteract this effect, it helps to carry information in the
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* entropy pool across shut-downs and start-ups. To do this, put the
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* following lines an appropriate script which is run during the boot
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* sequence:
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*
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* echo "Initializing random number generator..."
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* random_seed=/var/run/random-seed
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* # Carry a random seed from start-up to start-up
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* # Load and then save the whole entropy pool
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* if [ -f $random_seed ]; then
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* cat $random_seed >/dev/urandom
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* else
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* touch $random_seed
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* fi
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* chmod 600 $random_seed
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* dd if=/dev/urandom of=$random_seed count=1 bs=512
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*
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* and the following lines in an appropriate script which is run as
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* the system is shutdown:
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*
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* # Carry a random seed from shut-down to start-up
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* # Save the whole entropy pool
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* echo "Saving random seed..."
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* random_seed=/var/run/random-seed
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* touch $random_seed
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* chmod 600 $random_seed
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* dd if=/dev/urandom of=$random_seed count=1 bs=512
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*
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* For example, on most modern systems using the System V init
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* scripts, such code fragments would be found in
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* /etc/rc.d/init.d/random. On older Linux systems, the correct script
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* location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0.
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*
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* Effectively, these commands cause the contents of the entropy pool
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* to be saved at shut-down time and reloaded into the entropy pool at
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* start-up. (The 'dd' in the addition to the bootup script is to
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* make sure that /etc/random-seed is different for every start-up,
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* even if the system crashes without executing rc.0.) Even with
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* complete knowledge of the start-up activities, predicting the state
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* of the entropy pool requires knowledge of the previous history of
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* the system.
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*
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* Configuring the /dev/random driver under Linux
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* ==============================================
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*
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* The /dev/random driver under Linux uses minor numbers 8 and 9 of
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* the /dev/mem major number (#1). So if your system does not have
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* /dev/random and /dev/urandom created already, they can be created
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* by using the commands:
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*
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* mknod /dev/random c 1 8
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* mknod /dev/urandom c 1 9
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*
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* Acknowledgements:
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* =================
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*
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* Ideas for constructing this random number generator were derived
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* from Pretty Good Privacy's random number generator, and from private
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* discussions with Phil Karn. Colin Plumb provided a faster random
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* number generator, which speed up the mixing function of the entropy
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* pool, taken from PGPfone. Dale Worley has also contributed many
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* useful ideas and suggestions to improve this driver.
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*
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* Any flaws in the design are solely my responsibility, and should
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* not be attributed to the Phil, Colin, or any of authors of PGP.
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*
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* Further background information on this topic may be obtained from
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* RFC 1750, "Randomness Recommendations for Security", by Donald
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* Eastlake, Steve Crocker, and Jeff Schiller.
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*/
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#include <linux/utsname.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/major.h>
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#include <linux/string.h>
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#include <linux/fcntl.h>
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#include <linux/slab.h>
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#include <linux/random.h>
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#include <linux/poll.h>
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/genhd.h>
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#include <linux/interrupt.h>
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#include <linux/mm.h>
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#include <linux/nodemask.h>
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#include <linux/spinlock.h>
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#include <linux/kthread.h>
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#include <linux/percpu.h>
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#include <linux/cryptohash.h>
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#include <linux/fips.h>
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#include <linux/ptrace.h>
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#include <linux/kmemcheck.h>
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#include <linux/workqueue.h>
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#include <linux/irq.h>
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#include <linux/syscalls.h>
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#include <linux/completion.h>
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#include <linux/uuid.h>
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#include <crypto/chacha20.h>
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#include <asm/processor.h>
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#include <linux/uaccess.h>
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#include <asm/irq.h>
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#include <asm/irq_regs.h>
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#include <asm/io.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/random.h>
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/* #define ADD_INTERRUPT_BENCH */
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/*
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* Configuration information
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*/
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#define INPUT_POOL_SHIFT 12
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#define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5))
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#define OUTPUT_POOL_SHIFT 10
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#define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5))
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#define SEC_XFER_SIZE 512
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#define EXTRACT_SIZE 10
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#define DEBUG_RANDOM_BOOT 0
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#define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long))
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/*
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* To allow fractional bits to be tracked, the entropy_count field is
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* denominated in units of 1/8th bits.
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*
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* 2*(ENTROPY_SHIFT + log2(poolbits)) must <= 31, or the multiply in
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* credit_entropy_bits() needs to be 64 bits wide.
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*/
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#define ENTROPY_SHIFT 3
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#define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT)
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/*
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* The minimum number of bits of entropy before we wake up a read on
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* /dev/random. Should be enough to do a significant reseed.
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*/
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static int random_read_wakeup_bits = 64;
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/*
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* If the entropy count falls under this number of bits, then we
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* should wake up processes which are selecting or polling on write
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* access to /dev/random.
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*/
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static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS;
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/*
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* Originally, we used a primitive polynomial of degree .poolwords
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* over GF(2). The taps for various sizes are defined below. They
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* were chosen to be evenly spaced except for the last tap, which is 1
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* to get the twisting happening as fast as possible.
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*
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* For the purposes of better mixing, we use the CRC-32 polynomial as
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* well to make a (modified) twisted Generalized Feedback Shift
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* Register. (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR
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* generators. ACM Transactions on Modeling and Computer Simulation
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* 2(3):179-194. Also see M. Matsumoto & Y. Kurita, 1994. Twisted
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* GFSR generators II. ACM Transactions on Modeling and Computer
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* Simulation 4:254-266)
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*
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* Thanks to Colin Plumb for suggesting this.
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*
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* The mixing operation is much less sensitive than the output hash,
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* where we use SHA-1. All that we want of mixing operation is that
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* it be a good non-cryptographic hash; i.e. it not produce collisions
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* when fed "random" data of the sort we expect to see. As long as
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* the pool state differs for different inputs, we have preserved the
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* input entropy and done a good job. The fact that an intelligent
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* attacker can construct inputs that will produce controlled
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* alterations to the pool's state is not important because we don't
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* consider such inputs to contribute any randomness. The only
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* property we need with respect to them is that the attacker can't
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* increase his/her knowledge of the pool's state. Since all
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* additions are reversible (knowing the final state and the input,
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* you can reconstruct the initial state), if an attacker has any
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* uncertainty about the initial state, he/she can only shuffle that
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* uncertainty about, but never cause any collisions (which would
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* decrease the uncertainty).
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*
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* Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and
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* Videau in their paper, "The Linux Pseudorandom Number Generator
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* Revisited" (see: http://eprint.iacr.org/2012/251.pdf). In their
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* paper, they point out that we are not using a true Twisted GFSR,
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* since Matsumoto & Kurita used a trinomial feedback polynomial (that
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* is, with only three taps, instead of the six that we are using).
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* As a result, the resulting polynomial is neither primitive nor
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* irreducible, and hence does not have a maximal period over
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* GF(2**32). They suggest a slight change to the generator
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* polynomial which improves the resulting TGFSR polynomial to be
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* irreducible, which we have made here.
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*/
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static struct poolinfo {
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int poolbitshift, poolwords, poolbytes, poolbits, poolfracbits;
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#define S(x) ilog2(x)+5, (x), (x)*4, (x)*32, (x) << (ENTROPY_SHIFT+5)
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int tap1, tap2, tap3, tap4, tap5;
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} poolinfo_table[] = {
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/* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */
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/* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */
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{ S(128), 104, 76, 51, 25, 1 },
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/* was: x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 */
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/* x^32 + x^26 + x^19 + x^14 + x^7 + x + 1 */
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{ S(32), 26, 19, 14, 7, 1 },
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#if 0
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/* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */
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{ S(2048), 1638, 1231, 819, 411, 1 },
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/* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */
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{ S(1024), 817, 615, 412, 204, 1 },
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/* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */
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{ S(1024), 819, 616, 410, 207, 2 },
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/* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */
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{ S(512), 411, 308, 208, 104, 1 },
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/* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */
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{ S(512), 409, 307, 206, 102, 2 },
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/* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */
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{ S(512), 409, 309, 205, 103, 2 },
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/* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */
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{ S(256), 205, 155, 101, 52, 1 },
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/* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */
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{ S(128), 103, 78, 51, 27, 2 },
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/* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */
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{ S(64), 52, 39, 26, 14, 1 },
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#endif
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};
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/*
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* Static global variables
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*/
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static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
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static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
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static struct fasync_struct *fasync;
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static DEFINE_SPINLOCK(random_ready_list_lock);
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static LIST_HEAD(random_ready_list);
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struct crng_state {
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__u32 state[16];
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unsigned long init_time;
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spinlock_t lock;
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};
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struct crng_state primary_crng = {
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.lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock),
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};
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/*
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* crng_init = 0 --> Uninitialized
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* 1 --> Initialized
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* 2 --> Initialized from input_pool
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*
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* crng_init is protected by primary_crng->lock, and only increases
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* its value (from 0->1->2).
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*/
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static int crng_init = 0;
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#define crng_ready() (likely(crng_init > 0))
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static int crng_init_cnt = 0;
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#define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE)
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static void _extract_crng(struct crng_state *crng,
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__u8 out[CHACHA20_BLOCK_SIZE]);
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static void _crng_backtrack_protect(struct crng_state *crng,
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__u8 tmp[CHACHA20_BLOCK_SIZE], int used);
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static void process_random_ready_list(void);
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|
|
/**********************************************************************
|
|
*
|
|
* OS independent entropy store. Here are the functions which handle
|
|
* storing entropy in an entropy pool.
|
|
*
|
|
**********************************************************************/
|
|
|
|
struct entropy_store;
|
|
struct entropy_store {
|
|
/* read-only data: */
|
|
const struct poolinfo *poolinfo;
|
|
__u32 *pool;
|
|
const char *name;
|
|
struct entropy_store *pull;
|
|
struct work_struct push_work;
|
|
|
|
/* read-write data: */
|
|
unsigned long last_pulled;
|
|
spinlock_t lock;
|
|
unsigned short add_ptr;
|
|
unsigned short input_rotate;
|
|
int entropy_count;
|
|
int entropy_total;
|
|
unsigned int initialized:1;
|
|
unsigned int last_data_init:1;
|
|
__u8 last_data[EXTRACT_SIZE];
|
|
};
|
|
|
|
static ssize_t extract_entropy(struct entropy_store *r, void *buf,
|
|
size_t nbytes, int min, int rsvd);
|
|
static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
|
|
size_t nbytes, int fips);
|
|
|
|
static void crng_reseed(struct crng_state *crng, struct entropy_store *r);
|
|
static void push_to_pool(struct work_struct *work);
|
|
static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy;
|
|
static __u32 blocking_pool_data[OUTPUT_POOL_WORDS] __latent_entropy;
|
|
|
|
static struct entropy_store input_pool = {
|
|
.poolinfo = &poolinfo_table[0],
|
|
.name = "input",
|
|
.lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
|
|
.pool = input_pool_data
|
|
};
|
|
|
|
static struct entropy_store blocking_pool = {
|
|
.poolinfo = &poolinfo_table[1],
|
|
.name = "blocking",
|
|
.pull = &input_pool,
|
|
.lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock),
|
|
.pool = blocking_pool_data,
|
|
.push_work = __WORK_INITIALIZER(blocking_pool.push_work,
|
|
push_to_pool),
|
|
};
|
|
|
|
static __u32 const twist_table[8] = {
|
|
0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
|
|
0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
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|
|
|
/*
|
|
* This function adds bytes into the entropy "pool". It does not
|
|
* update the entropy estimate. The caller should call
|
|
* credit_entropy_bits if this is appropriate.
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|
*
|
|
* The pool is stirred with a primitive polynomial of the appropriate
|
|
* degree, and then twisted. We twist by three bits at a time because
|
|
* it's cheap to do so and helps slightly in the expected case where
|
|
* the entropy is concentrated in the low-order bits.
|
|
*/
|
|
static void _mix_pool_bytes(struct entropy_store *r, const void *in,
|
|
int nbytes)
|
|
{
|
|
unsigned long i, tap1, tap2, tap3, tap4, tap5;
|
|
int input_rotate;
|
|
int wordmask = r->poolinfo->poolwords - 1;
|
|
const char *bytes = in;
|
|
__u32 w;
|
|
|
|
tap1 = r->poolinfo->tap1;
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|
tap2 = r->poolinfo->tap2;
|
|
tap3 = r->poolinfo->tap3;
|
|
tap4 = r->poolinfo->tap4;
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|
tap5 = r->poolinfo->tap5;
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|
|
|
input_rotate = r->input_rotate;
|
|
i = r->add_ptr;
|
|
|
|
/* mix one byte at a time to simplify size handling and churn faster */
|
|
while (nbytes--) {
|
|
w = rol32(*bytes++, input_rotate);
|
|
i = (i - 1) & wordmask;
|
|
|
|
/* XOR in the various taps */
|
|
w ^= r->pool[i];
|
|
w ^= r->pool[(i + tap1) & wordmask];
|
|
w ^= r->pool[(i + tap2) & wordmask];
|
|
w ^= r->pool[(i + tap3) & wordmask];
|
|
w ^= r->pool[(i + tap4) & wordmask];
|
|
w ^= r->pool[(i + tap5) & wordmask];
|
|
|
|
/* Mix the result back in with a twist */
|
|
r->pool[i] = (w >> 3) ^ twist_table[w & 7];
|
|
|
|
/*
|
|
* Normally, we add 7 bits of rotation to the pool.
|
|
* At the beginning of the pool, add an extra 7 bits
|
|
* rotation, so that successive passes spread the
|
|
* input bits across the pool evenly.
|
|
*/
|
|
input_rotate = (input_rotate + (i ? 7 : 14)) & 31;
|
|
}
|
|
|
|
r->input_rotate = input_rotate;
|
|
r->add_ptr = i;
|
|
}
|
|
|
|
static void __mix_pool_bytes(struct entropy_store *r, const void *in,
|
|
int nbytes)
|
|
{
|
|
trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_);
|
|
_mix_pool_bytes(r, in, nbytes);
|
|
}
|
|
|
|
static void mix_pool_bytes(struct entropy_store *r, const void *in,
|
|
int nbytes)
|
|
{
|
|
unsigned long flags;
|
|
|
|
trace_mix_pool_bytes(r->name, nbytes, _RET_IP_);
|
|
spin_lock_irqsave(&r->lock, flags);
|
|
_mix_pool_bytes(r, in, nbytes);
|
|
spin_unlock_irqrestore(&r->lock, flags);
|
|
}
|
|
|
|
struct fast_pool {
|
|
__u32 pool[4];
|
|
unsigned long last;
|
|
unsigned short reg_idx;
|
|
unsigned char count;
|
|
};
|
|
|
|
/*
|
|
* This is a fast mixing routine used by the interrupt randomness
|
|
* collector. It's hardcoded for an 128 bit pool and assumes that any
|
|
* locks that might be needed are taken by the caller.
|
|
*/
|
|
static void fast_mix(struct fast_pool *f)
|
|
{
|
|
__u32 a = f->pool[0], b = f->pool[1];
|
|
__u32 c = f->pool[2], d = f->pool[3];
|
|
|
|
a += b; c += d;
|
|
b = rol32(b, 6); d = rol32(d, 27);
|
|
d ^= a; b ^= c;
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|
|
|
a += b; c += d;
|
|
b = rol32(b, 16); d = rol32(d, 14);
|
|
d ^= a; b ^= c;
|
|
|
|
a += b; c += d;
|
|
b = rol32(b, 6); d = rol32(d, 27);
|
|
d ^= a; b ^= c;
|
|
|
|
a += b; c += d;
|
|
b = rol32(b, 16); d = rol32(d, 14);
|
|
d ^= a; b ^= c;
|
|
|
|
f->pool[0] = a; f->pool[1] = b;
|
|
f->pool[2] = c; f->pool[3] = d;
|
|
f->count++;
|
|
}
|
|
|
|
static void process_random_ready_list(void)
|
|
{
|
|
unsigned long flags;
|
|
struct random_ready_callback *rdy, *tmp;
|
|
|
|
spin_lock_irqsave(&random_ready_list_lock, flags);
|
|
list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
|
|
struct module *owner = rdy->owner;
|
|
|
|
list_del_init(&rdy->list);
|
|
rdy->func(rdy);
|
|
module_put(owner);
|
|
}
|
|
spin_unlock_irqrestore(&random_ready_list_lock, flags);
|
|
}
|
|
|
|
/*
|
|
* Credit (or debit) the entropy store with n bits of entropy.
|
|
* Use credit_entropy_bits_safe() if the value comes from userspace
|
|
* or otherwise should be checked for extreme values.
|
|
*/
|
|
static void credit_entropy_bits(struct entropy_store *r, int nbits)
|
|
{
|
|
int entropy_count, orig;
|
|
const int pool_size = r->poolinfo->poolfracbits;
|
|
int nfrac = nbits << ENTROPY_SHIFT;
|
|
|
|
if (!nbits)
|
|
return;
|
|
|
|
retry:
|
|
entropy_count = orig = ACCESS_ONCE(r->entropy_count);
|
|
if (nfrac < 0) {
|
|
/* Debit */
|
|
entropy_count += nfrac;
|
|
} else {
|
|
/*
|
|
* Credit: we have to account for the possibility of
|
|
* overwriting already present entropy. Even in the
|
|
* ideal case of pure Shannon entropy, new contributions
|
|
* approach the full value asymptotically:
|
|
*
|
|
* entropy <- entropy + (pool_size - entropy) *
|
|
* (1 - exp(-add_entropy/pool_size))
|
|
*
|
|
* For add_entropy <= pool_size/2 then
|
|
* (1 - exp(-add_entropy/pool_size)) >=
|
|
* (add_entropy/pool_size)*0.7869...
|
|
* so we can approximate the exponential with
|
|
* 3/4*add_entropy/pool_size and still be on the
|
|
* safe side by adding at most pool_size/2 at a time.
|
|
*
|
|
* The use of pool_size-2 in the while statement is to
|
|
* prevent rounding artifacts from making the loop
|
|
* arbitrarily long; this limits the loop to log2(pool_size)*2
|
|
* turns no matter how large nbits is.
|
|
*/
|
|
int pnfrac = nfrac;
|
|
const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2;
|
|
/* The +2 corresponds to the /4 in the denominator */
|
|
|
|
do {
|
|
unsigned int anfrac = min(pnfrac, pool_size/2);
|
|
unsigned int add =
|
|
((pool_size - entropy_count)*anfrac*3) >> s;
|
|
|
|
entropy_count += add;
|
|
pnfrac -= anfrac;
|
|
} while (unlikely(entropy_count < pool_size-2 && pnfrac));
|
|
}
|
|
|
|
if (unlikely(entropy_count < 0)) {
|
|
pr_warn("random: negative entropy/overflow: pool %s count %d\n",
|
|
r->name, entropy_count);
|
|
WARN_ON(1);
|
|
entropy_count = 0;
|
|
} else if (entropy_count > pool_size)
|
|
entropy_count = pool_size;
|
|
if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
|
|
goto retry;
|
|
|
|
r->entropy_total += nbits;
|
|
if (!r->initialized && r->entropy_total > 128) {
|
|
r->initialized = 1;
|
|
r->entropy_total = 0;
|
|
}
|
|
|
|
trace_credit_entropy_bits(r->name, nbits,
|
|
entropy_count >> ENTROPY_SHIFT,
|
|
r->entropy_total, _RET_IP_);
|
|
|
|
if (r == &input_pool) {
|
|
int entropy_bits = entropy_count >> ENTROPY_SHIFT;
|
|
|
|
if (crng_init < 2 && entropy_bits >= 128) {
|
|
crng_reseed(&primary_crng, r);
|
|
entropy_bits = r->entropy_count >> ENTROPY_SHIFT;
|
|
}
|
|
|
|
/* should we wake readers? */
|
|
if (entropy_bits >= random_read_wakeup_bits) {
|
|
wake_up_interruptible(&random_read_wait);
|
|
kill_fasync(&fasync, SIGIO, POLL_IN);
|
|
}
|
|
/* If the input pool is getting full, send some
|
|
* entropy to the blocking pool until it is 75% full.
|
|
*/
|
|
if (entropy_bits > random_write_wakeup_bits &&
|
|
r->initialized &&
|
|
r->entropy_total >= 2*random_read_wakeup_bits) {
|
|
struct entropy_store *other = &blocking_pool;
|
|
|
|
if (other->entropy_count <=
|
|
3 * other->poolinfo->poolfracbits / 4) {
|
|
schedule_work(&other->push_work);
|
|
r->entropy_total = 0;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
static int credit_entropy_bits_safe(struct entropy_store *r, int nbits)
|
|
{
|
|
const int nbits_max = (int)(~0U >> (ENTROPY_SHIFT + 1));
|
|
|
|
if (nbits < 0)
|
|
return -EINVAL;
|
|
|
|
/* Cap the value to avoid overflows */
|
|
nbits = min(nbits, nbits_max);
|
|
|
|
credit_entropy_bits(r, nbits);
|
|
return 0;
|
|
}
|
|
|
|
/*********************************************************************
|
|
*
|
|
* CRNG using CHACHA20
|
|
*
|
|
*********************************************************************/
|
|
|
|
#define CRNG_RESEED_INTERVAL (300*HZ)
|
|
|
|
static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
|
|
|
|
#ifdef CONFIG_NUMA
|
|
/*
|
|
* Hack to deal with crazy userspace progams when they are all trying
|
|
* to access /dev/urandom in parallel. The programs are almost
|
|
* certainly doing something terribly wrong, but we'll work around
|
|
* their brain damage.
|
|
*/
|
|
static struct crng_state **crng_node_pool __read_mostly;
|
|
#endif
|
|
|
|
static void invalidate_batched_entropy(void);
|
|
|
|
static void crng_initialize(struct crng_state *crng)
|
|
{
|
|
int i;
|
|
unsigned long rv;
|
|
|
|
memcpy(&crng->state[0], "expand 32-byte k", 16);
|
|
if (crng == &primary_crng)
|
|
_extract_entropy(&input_pool, &crng->state[4],
|
|
sizeof(__u32) * 12, 0);
|
|
else
|
|
get_random_bytes(&crng->state[4], sizeof(__u32) * 12);
|
|
for (i = 4; i < 16; i++) {
|
|
if (!arch_get_random_seed_long(&rv) &&
|
|
!arch_get_random_long(&rv))
|
|
rv = random_get_entropy();
|
|
crng->state[i] ^= rv;
|
|
}
|
|
crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
|
|
}
|
|
|
|
static int crng_fast_load(const char *cp, size_t len)
|
|
{
|
|
unsigned long flags;
|
|
char *p;
|
|
|
|
if (!spin_trylock_irqsave(&primary_crng.lock, flags))
|
|
return 0;
|
|
if (crng_ready()) {
|
|
spin_unlock_irqrestore(&primary_crng.lock, flags);
|
|
return 0;
|
|
}
|
|
p = (unsigned char *) &primary_crng.state[4];
|
|
while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) {
|
|
p[crng_init_cnt % CHACHA20_KEY_SIZE] ^= *cp;
|
|
cp++; crng_init_cnt++; len--;
|
|
}
|
|
spin_unlock_irqrestore(&primary_crng.lock, flags);
|
|
if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
|
|
invalidate_batched_entropy();
|
|
crng_init = 1;
|
|
wake_up_interruptible(&crng_init_wait);
|
|
pr_notice("random: fast init done\n");
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
|
|
{
|
|
unsigned long flags;
|
|
int i, num;
|
|
union {
|
|
__u8 block[CHACHA20_BLOCK_SIZE];
|
|
__u32 key[8];
|
|
} buf;
|
|
|
|
if (r) {
|
|
num = extract_entropy(r, &buf, 32, 16, 0);
|
|
if (num == 0)
|
|
return;
|
|
} else {
|
|
_extract_crng(&primary_crng, buf.block);
|
|
_crng_backtrack_protect(&primary_crng, buf.block,
|
|
CHACHA20_KEY_SIZE);
|
|
}
|
|
spin_lock_irqsave(&primary_crng.lock, flags);
|
|
for (i = 0; i < 8; i++) {
|
|
unsigned long rv;
|
|
if (!arch_get_random_seed_long(&rv) &&
|
|
!arch_get_random_long(&rv))
|
|
rv = random_get_entropy();
|
|
crng->state[i+4] ^= buf.key[i] ^ rv;
|
|
}
|
|
memzero_explicit(&buf, sizeof(buf));
|
|
crng->init_time = jiffies;
|
|
spin_unlock_irqrestore(&primary_crng.lock, flags);
|
|
if (crng == &primary_crng && crng_init < 2) {
|
|
invalidate_batched_entropy();
|
|
crng_init = 2;
|
|
process_random_ready_list();
|
|
wake_up_interruptible(&crng_init_wait);
|
|
pr_notice("random: crng init done\n");
|
|
}
|
|
}
|
|
|
|
static inline void crng_wait_ready(void)
|
|
{
|
|
wait_event_interruptible(crng_init_wait, crng_ready());
|
|
}
|
|
|
|
static void _extract_crng(struct crng_state *crng,
|
|
__u8 out[CHACHA20_BLOCK_SIZE])
|
|
{
|
|
unsigned long v, flags;
|
|
|
|
if (crng_init > 1 &&
|
|
time_after(jiffies, crng->init_time + CRNG_RESEED_INTERVAL))
|
|
crng_reseed(crng, crng == &primary_crng ? &input_pool : NULL);
|
|
spin_lock_irqsave(&crng->lock, flags);
|
|
if (arch_get_random_long(&v))
|
|
crng->state[14] ^= v;
|
|
chacha20_block(&crng->state[0], out);
|
|
if (crng->state[12] == 0)
|
|
crng->state[13]++;
|
|
spin_unlock_irqrestore(&crng->lock, flags);
|
|
}
|
|
|
|
static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE])
|
|
{
|
|
struct crng_state *crng = NULL;
|
|
|
|
#ifdef CONFIG_NUMA
|
|
if (crng_node_pool)
|
|
crng = crng_node_pool[numa_node_id()];
|
|
if (crng == NULL)
|
|
#endif
|
|
crng = &primary_crng;
|
|
_extract_crng(crng, out);
|
|
}
|
|
|
|
/*
|
|
* Use the leftover bytes from the CRNG block output (if there is
|
|
* enough) to mutate the CRNG key to provide backtracking protection.
|
|
*/
|
|
static void _crng_backtrack_protect(struct crng_state *crng,
|
|
__u8 tmp[CHACHA20_BLOCK_SIZE], int used)
|
|
{
|
|
unsigned long flags;
|
|
__u32 *s, *d;
|
|
int i;
|
|
|
|
used = round_up(used, sizeof(__u32));
|
|
if (used + CHACHA20_KEY_SIZE > CHACHA20_BLOCK_SIZE) {
|
|
extract_crng(tmp);
|
|
used = 0;
|
|
}
|
|
spin_lock_irqsave(&crng->lock, flags);
|
|
s = (__u32 *) &tmp[used];
|
|
d = &crng->state[4];
|
|
for (i=0; i < 8; i++)
|
|
*d++ ^= *s++;
|
|
spin_unlock_irqrestore(&crng->lock, flags);
|
|
}
|
|
|
|
static void crng_backtrack_protect(__u8 tmp[CHACHA20_BLOCK_SIZE], int used)
|
|
{
|
|
struct crng_state *crng = NULL;
|
|
|
|
#ifdef CONFIG_NUMA
|
|
if (crng_node_pool)
|
|
crng = crng_node_pool[numa_node_id()];
|
|
if (crng == NULL)
|
|
#endif
|
|
crng = &primary_crng;
|
|
_crng_backtrack_protect(crng, tmp, used);
|
|
}
|
|
|
|
static ssize_t extract_crng_user(void __user *buf, size_t nbytes)
|
|
{
|
|
ssize_t ret = 0, i = CHACHA20_BLOCK_SIZE;
|
|
__u8 tmp[CHACHA20_BLOCK_SIZE];
|
|
int large_request = (nbytes > 256);
|
|
|
|
while (nbytes) {
|
|
if (large_request && need_resched()) {
|
|
if (signal_pending(current)) {
|
|
if (ret == 0)
|
|
ret = -ERESTARTSYS;
|
|
break;
|
|
}
|
|
schedule();
|
|
}
|
|
|
|
extract_crng(tmp);
|
|
i = min_t(int, nbytes, CHACHA20_BLOCK_SIZE);
|
|
if (copy_to_user(buf, tmp, i)) {
|
|
ret = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
nbytes -= i;
|
|
buf += i;
|
|
ret += i;
|
|
}
|
|
crng_backtrack_protect(tmp, i);
|
|
|
|
/* Wipe data just written to memory */
|
|
memzero_explicit(tmp, sizeof(tmp));
|
|
|
|
return ret;
|
|
}
|
|
|
|
|
|
/*********************************************************************
|
|
*
|
|
* Entropy input management
|
|
*
|
|
*********************************************************************/
|
|
|
|
/* There is one of these per entropy source */
|
|
struct timer_rand_state {
|
|
cycles_t last_time;
|
|
long last_delta, last_delta2;
|
|
unsigned dont_count_entropy:1;
|
|
};
|
|
|
|
#define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, };
|
|
|
|
/*
|
|
* Add device- or boot-specific data to the input pool to help
|
|
* initialize it.
|
|
*
|
|
* None of this adds any entropy; it is meant to avoid the problem of
|
|
* the entropy pool having similar initial state across largely
|
|
* identical devices.
|
|
*/
|
|
void add_device_randomness(const void *buf, unsigned int size)
|
|
{
|
|
unsigned long time = random_get_entropy() ^ jiffies;
|
|
unsigned long flags;
|
|
|
|
if (!crng_ready()) {
|
|
crng_fast_load(buf, size);
|
|
return;
|
|
}
|
|
|
|
trace_add_device_randomness(size, _RET_IP_);
|
|
spin_lock_irqsave(&input_pool.lock, flags);
|
|
_mix_pool_bytes(&input_pool, buf, size);
|
|
_mix_pool_bytes(&input_pool, &time, sizeof(time));
|
|
spin_unlock_irqrestore(&input_pool.lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(add_device_randomness);
|
|
|
|
static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE;
|
|
|
|
/*
|
|
* This function adds entropy to the entropy "pool" by using timing
|
|
* delays. It uses the timer_rand_state structure to make an estimate
|
|
* of how many bits of entropy this call has added to the pool.
|
|
*
|
|
* The number "num" is also added to the pool - it should somehow describe
|
|
* the type of event which just happened. This is currently 0-255 for
|
|
* keyboard scan codes, and 256 upwards for interrupts.
|
|
*
|
|
*/
|
|
static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
|
|
{
|
|
struct entropy_store *r;
|
|
struct {
|
|
long jiffies;
|
|
unsigned cycles;
|
|
unsigned num;
|
|
} sample;
|
|
long delta, delta2, delta3;
|
|
|
|
preempt_disable();
|
|
|
|
sample.jiffies = jiffies;
|
|
sample.cycles = random_get_entropy();
|
|
sample.num = num;
|
|
r = &input_pool;
|
|
mix_pool_bytes(r, &sample, sizeof(sample));
|
|
|
|
/*
|
|
* Calculate number of bits of randomness we probably added.
|
|
* We take into account the first, second and third-order deltas
|
|
* in order to make our estimate.
|
|
*/
|
|
|
|
if (!state->dont_count_entropy) {
|
|
delta = sample.jiffies - state->last_time;
|
|
state->last_time = sample.jiffies;
|
|
|
|
delta2 = delta - state->last_delta;
|
|
state->last_delta = delta;
|
|
|
|
delta3 = delta2 - state->last_delta2;
|
|
state->last_delta2 = delta2;
|
|
|
|
if (delta < 0)
|
|
delta = -delta;
|
|
if (delta2 < 0)
|
|
delta2 = -delta2;
|
|
if (delta3 < 0)
|
|
delta3 = -delta3;
|
|
if (delta > delta2)
|
|
delta = delta2;
|
|
if (delta > delta3)
|
|
delta = delta3;
|
|
|
|
/*
|
|
* delta is now minimum absolute delta.
|
|
* Round down by 1 bit on general principles,
|
|
* and limit entropy entimate to 12 bits.
|
|
*/
|
|
credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
|
|
}
|
|
preempt_enable();
|
|
}
|
|
|
|
void add_input_randomness(unsigned int type, unsigned int code,
|
|
unsigned int value)
|
|
{
|
|
static unsigned char last_value;
|
|
|
|
/* ignore autorepeat and the like */
|
|
if (value == last_value)
|
|
return;
|
|
|
|
last_value = value;
|
|
add_timer_randomness(&input_timer_state,
|
|
(type << 4) ^ code ^ (code >> 4) ^ value);
|
|
trace_add_input_randomness(ENTROPY_BITS(&input_pool));
|
|
}
|
|
EXPORT_SYMBOL_GPL(add_input_randomness);
|
|
|
|
static DEFINE_PER_CPU(struct fast_pool, irq_randomness);
|
|
|
|
#ifdef ADD_INTERRUPT_BENCH
|
|
static unsigned long avg_cycles, avg_deviation;
|
|
|
|
#define AVG_SHIFT 8 /* Exponential average factor k=1/256 */
|
|
#define FIXED_1_2 (1 << (AVG_SHIFT-1))
|
|
|
|
static void add_interrupt_bench(cycles_t start)
|
|
{
|
|
long delta = random_get_entropy() - start;
|
|
|
|
/* Use a weighted moving average */
|
|
delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT);
|
|
avg_cycles += delta;
|
|
/* And average deviation */
|
|
delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT);
|
|
avg_deviation += delta;
|
|
}
|
|
#else
|
|
#define add_interrupt_bench(x)
|
|
#endif
|
|
|
|
static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
|
|
{
|
|
__u32 *ptr = (__u32 *) regs;
|
|
unsigned int idx;
|
|
|
|
if (regs == NULL)
|
|
return 0;
|
|
idx = READ_ONCE(f->reg_idx);
|
|
if (idx >= sizeof(struct pt_regs) / sizeof(__u32))
|
|
idx = 0;
|
|
ptr += idx++;
|
|
WRITE_ONCE(f->reg_idx, idx);
|
|
return *ptr;
|
|
}
|
|
|
|
void add_interrupt_randomness(int irq, int irq_flags)
|
|
{
|
|
struct entropy_store *r;
|
|
struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
|
|
struct pt_regs *regs = get_irq_regs();
|
|
unsigned long now = jiffies;
|
|
cycles_t cycles = random_get_entropy();
|
|
__u32 c_high, j_high;
|
|
__u64 ip;
|
|
unsigned long seed;
|
|
int credit = 0;
|
|
|
|
if (cycles == 0)
|
|
cycles = get_reg(fast_pool, regs);
|
|
c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0;
|
|
j_high = (sizeof(now) > 4) ? now >> 32 : 0;
|
|
fast_pool->pool[0] ^= cycles ^ j_high ^ irq;
|
|
fast_pool->pool[1] ^= now ^ c_high;
|
|
ip = regs ? instruction_pointer(regs) : _RET_IP_;
|
|
fast_pool->pool[2] ^= ip;
|
|
fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 :
|
|
get_reg(fast_pool, regs);
|
|
|
|
fast_mix(fast_pool);
|
|
add_interrupt_bench(cycles);
|
|
|
|
if (!crng_ready()) {
|
|
if ((fast_pool->count >= 64) &&
|
|
crng_fast_load((char *) fast_pool->pool,
|
|
sizeof(fast_pool->pool))) {
|
|
fast_pool->count = 0;
|
|
fast_pool->last = now;
|
|
}
|
|
return;
|
|
}
|
|
|
|
if ((fast_pool->count < 64) &&
|
|
!time_after(now, fast_pool->last + HZ))
|
|
return;
|
|
|
|
r = &input_pool;
|
|
if (!spin_trylock(&r->lock))
|
|
return;
|
|
|
|
fast_pool->last = now;
|
|
__mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool));
|
|
|
|
/*
|
|
* If we have architectural seed generator, produce a seed and
|
|
* add it to the pool. For the sake of paranoia don't let the
|
|
* architectural seed generator dominate the input from the
|
|
* interrupt noise.
|
|
*/
|
|
if (arch_get_random_seed_long(&seed)) {
|
|
__mix_pool_bytes(r, &seed, sizeof(seed));
|
|
credit = 1;
|
|
}
|
|
spin_unlock(&r->lock);
|
|
|
|
fast_pool->count = 0;
|
|
|
|
/* award one bit for the contents of the fast pool */
|
|
credit_entropy_bits(r, credit + 1);
|
|
}
|
|
EXPORT_SYMBOL_GPL(add_interrupt_randomness);
|
|
|
|
#ifdef CONFIG_BLOCK
|
|
void add_disk_randomness(struct gendisk *disk)
|
|
{
|
|
if (!disk || !disk->random)
|
|
return;
|
|
/* first major is 1, so we get >= 0x200 here */
|
|
add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
|
|
trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool));
|
|
}
|
|
EXPORT_SYMBOL_GPL(add_disk_randomness);
|
|
#endif
|
|
|
|
/*********************************************************************
|
|
*
|
|
* Entropy extraction routines
|
|
*
|
|
*********************************************************************/
|
|
|
|
/*
|
|
* This utility inline function is responsible for transferring entropy
|
|
* from the primary pool to the secondary extraction pool. We make
|
|
* sure we pull enough for a 'catastrophic reseed'.
|
|
*/
|
|
static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes);
|
|
static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
|
|
{
|
|
if (!r->pull ||
|
|
r->entropy_count >= (nbytes << (ENTROPY_SHIFT + 3)) ||
|
|
r->entropy_count > r->poolinfo->poolfracbits)
|
|
return;
|
|
|
|
_xfer_secondary_pool(r, nbytes);
|
|
}
|
|
|
|
static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
|
|
{
|
|
__u32 tmp[OUTPUT_POOL_WORDS];
|
|
|
|
int bytes = nbytes;
|
|
|
|
/* pull at least as much as a wakeup */
|
|
bytes = max_t(int, bytes, random_read_wakeup_bits / 8);
|
|
/* but never more than the buffer size */
|
|
bytes = min_t(int, bytes, sizeof(tmp));
|
|
|
|
trace_xfer_secondary_pool(r->name, bytes * 8, nbytes * 8,
|
|
ENTROPY_BITS(r), ENTROPY_BITS(r->pull));
|
|
bytes = extract_entropy(r->pull, tmp, bytes,
|
|
random_read_wakeup_bits / 8, 0);
|
|
mix_pool_bytes(r, tmp, bytes);
|
|
credit_entropy_bits(r, bytes*8);
|
|
}
|
|
|
|
/*
|
|
* Used as a workqueue function so that when the input pool is getting
|
|
* full, we can "spill over" some entropy to the output pools. That
|
|
* way the output pools can store some of the excess entropy instead
|
|
* of letting it go to waste.
|
|
*/
|
|
static void push_to_pool(struct work_struct *work)
|
|
{
|
|
struct entropy_store *r = container_of(work, struct entropy_store,
|
|
push_work);
|
|
BUG_ON(!r);
|
|
_xfer_secondary_pool(r, random_read_wakeup_bits/8);
|
|
trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT,
|
|
r->pull->entropy_count >> ENTROPY_SHIFT);
|
|
}
|
|
|
|
/*
|
|
* This function decides how many bytes to actually take from the
|
|
* given pool, and also debits the entropy count accordingly.
|
|
*/
|
|
static size_t account(struct entropy_store *r, size_t nbytes, int min,
|
|
int reserved)
|
|
{
|
|
int entropy_count, orig, have_bytes;
|
|
size_t ibytes, nfrac;
|
|
|
|
BUG_ON(r->entropy_count > r->poolinfo->poolfracbits);
|
|
|
|
/* Can we pull enough? */
|
|
retry:
|
|
entropy_count = orig = ACCESS_ONCE(r->entropy_count);
|
|
ibytes = nbytes;
|
|
/* never pull more than available */
|
|
have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
|
|
|
|
if ((have_bytes -= reserved) < 0)
|
|
have_bytes = 0;
|
|
ibytes = min_t(size_t, ibytes, have_bytes);
|
|
if (ibytes < min)
|
|
ibytes = 0;
|
|
|
|
if (unlikely(entropy_count < 0)) {
|
|
pr_warn("random: negative entropy count: pool %s count %d\n",
|
|
r->name, entropy_count);
|
|
WARN_ON(1);
|
|
entropy_count = 0;
|
|
}
|
|
nfrac = ibytes << (ENTROPY_SHIFT + 3);
|
|
if ((size_t) entropy_count > nfrac)
|
|
entropy_count -= nfrac;
|
|
else
|
|
entropy_count = 0;
|
|
|
|
if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
|
|
goto retry;
|
|
|
|
trace_debit_entropy(r->name, 8 * ibytes);
|
|
if (ibytes &&
|
|
(r->entropy_count >> ENTROPY_SHIFT) < random_write_wakeup_bits) {
|
|
wake_up_interruptible(&random_write_wait);
|
|
kill_fasync(&fasync, SIGIO, POLL_OUT);
|
|
}
|
|
|
|
return ibytes;
|
|
}
|
|
|
|
/*
|
|
* This function does the actual extraction for extract_entropy and
|
|
* extract_entropy_user.
|
|
*
|
|
* Note: we assume that .poolwords is a multiple of 16 words.
|
|
*/
|
|
static void extract_buf(struct entropy_store *r, __u8 *out)
|
|
{
|
|
int i;
|
|
union {
|
|
__u32 w[5];
|
|
unsigned long l[LONGS(20)];
|
|
} hash;
|
|
__u32 workspace[SHA_WORKSPACE_WORDS];
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* If we have an architectural hardware random number
|
|
* generator, use it for SHA's initial vector
|
|
*/
|
|
sha_init(hash.w);
|
|
for (i = 0; i < LONGS(20); i++) {
|
|
unsigned long v;
|
|
if (!arch_get_random_long(&v))
|
|
break;
|
|
hash.l[i] = v;
|
|
}
|
|
|
|
/* Generate a hash across the pool, 16 words (512 bits) at a time */
|
|
spin_lock_irqsave(&r->lock, flags);
|
|
for (i = 0; i < r->poolinfo->poolwords; i += 16)
|
|
sha_transform(hash.w, (__u8 *)(r->pool + i), workspace);
|
|
|
|
/*
|
|
* We mix the hash back into the pool to prevent backtracking
|
|
* attacks (where the attacker knows the state of the pool
|
|
* plus the current outputs, and attempts to find previous
|
|
* ouputs), unless the hash function can be inverted. By
|
|
* mixing at least a SHA1 worth of hash data back, we make
|
|
* brute-forcing the feedback as hard as brute-forcing the
|
|
* hash.
|
|
*/
|
|
__mix_pool_bytes(r, hash.w, sizeof(hash.w));
|
|
spin_unlock_irqrestore(&r->lock, flags);
|
|
|
|
memzero_explicit(workspace, sizeof(workspace));
|
|
|
|
/*
|
|
* In case the hash function has some recognizable output
|
|
* pattern, we fold it in half. Thus, we always feed back
|
|
* twice as much data as we output.
|
|
*/
|
|
hash.w[0] ^= hash.w[3];
|
|
hash.w[1] ^= hash.w[4];
|
|
hash.w[2] ^= rol32(hash.w[2], 16);
|
|
|
|
memcpy(out, &hash, EXTRACT_SIZE);
|
|
memzero_explicit(&hash, sizeof(hash));
|
|
}
|
|
|
|
static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
|
|
size_t nbytes, int fips)
|
|
{
|
|
ssize_t ret = 0, i;
|
|
__u8 tmp[EXTRACT_SIZE];
|
|
unsigned long flags;
|
|
|
|
while (nbytes) {
|
|
extract_buf(r, tmp);
|
|
|
|
if (fips) {
|
|
spin_lock_irqsave(&r->lock, flags);
|
|
if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
|
|
panic("Hardware RNG duplicated output!\n");
|
|
memcpy(r->last_data, tmp, EXTRACT_SIZE);
|
|
spin_unlock_irqrestore(&r->lock, flags);
|
|
}
|
|
i = min_t(int, nbytes, EXTRACT_SIZE);
|
|
memcpy(buf, tmp, i);
|
|
nbytes -= i;
|
|
buf += i;
|
|
ret += i;
|
|
}
|
|
|
|
/* Wipe data just returned from memory */
|
|
memzero_explicit(tmp, sizeof(tmp));
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This function extracts randomness from the "entropy pool", and
|
|
* returns it in a buffer.
|
|
*
|
|
* The min parameter specifies the minimum amount we can pull before
|
|
* failing to avoid races that defeat catastrophic reseeding while the
|
|
* reserved parameter indicates how much entropy we must leave in the
|
|
* pool after each pull to avoid starving other readers.
|
|
*/
|
|
static ssize_t extract_entropy(struct entropy_store *r, void *buf,
|
|
size_t nbytes, int min, int reserved)
|
|
{
|
|
__u8 tmp[EXTRACT_SIZE];
|
|
unsigned long flags;
|
|
|
|
/* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
|
|
if (fips_enabled) {
|
|
spin_lock_irqsave(&r->lock, flags);
|
|
if (!r->last_data_init) {
|
|
r->last_data_init = 1;
|
|
spin_unlock_irqrestore(&r->lock, flags);
|
|
trace_extract_entropy(r->name, EXTRACT_SIZE,
|
|
ENTROPY_BITS(r), _RET_IP_);
|
|
xfer_secondary_pool(r, EXTRACT_SIZE);
|
|
extract_buf(r, tmp);
|
|
spin_lock_irqsave(&r->lock, flags);
|
|
memcpy(r->last_data, tmp, EXTRACT_SIZE);
|
|
}
|
|
spin_unlock_irqrestore(&r->lock, flags);
|
|
}
|
|
|
|
trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
|
|
xfer_secondary_pool(r, nbytes);
|
|
nbytes = account(r, nbytes, min, reserved);
|
|
|
|
return _extract_entropy(r, buf, nbytes, fips_enabled);
|
|
}
|
|
|
|
/*
|
|
* This function extracts randomness from the "entropy pool", and
|
|
* returns it in a userspace buffer.
|
|
*/
|
|
static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
|
|
size_t nbytes)
|
|
{
|
|
ssize_t ret = 0, i;
|
|
__u8 tmp[EXTRACT_SIZE];
|
|
int large_request = (nbytes > 256);
|
|
|
|
trace_extract_entropy_user(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
|
|
xfer_secondary_pool(r, nbytes);
|
|
nbytes = account(r, nbytes, 0, 0);
|
|
|
|
while (nbytes) {
|
|
if (large_request && need_resched()) {
|
|
if (signal_pending(current)) {
|
|
if (ret == 0)
|
|
ret = -ERESTARTSYS;
|
|
break;
|
|
}
|
|
schedule();
|
|
}
|
|
|
|
extract_buf(r, tmp);
|
|
i = min_t(int, nbytes, EXTRACT_SIZE);
|
|
if (copy_to_user(buf, tmp, i)) {
|
|
ret = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
nbytes -= i;
|
|
buf += i;
|
|
ret += i;
|
|
}
|
|
|
|
/* Wipe data just returned from memory */
|
|
memzero_explicit(tmp, sizeof(tmp));
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This function is the exported kernel interface. It returns some
|
|
* number of good random numbers, suitable for key generation, seeding
|
|
* TCP sequence numbers, etc. It does not rely on the hardware random
|
|
* number generator. For random bytes direct from the hardware RNG
|
|
* (when available), use get_random_bytes_arch().
|
|
*/
|
|
void get_random_bytes(void *buf, int nbytes)
|
|
{
|
|
__u8 tmp[CHACHA20_BLOCK_SIZE];
|
|
|
|
#if DEBUG_RANDOM_BOOT > 0
|
|
if (!crng_ready())
|
|
printk(KERN_NOTICE "random: %pF get_random_bytes called "
|
|
"with crng_init = %d\n", (void *) _RET_IP_, crng_init);
|
|
#endif
|
|
trace_get_random_bytes(nbytes, _RET_IP_);
|
|
|
|
while (nbytes >= CHACHA20_BLOCK_SIZE) {
|
|
extract_crng(buf);
|
|
buf += CHACHA20_BLOCK_SIZE;
|
|
nbytes -= CHACHA20_BLOCK_SIZE;
|
|
}
|
|
|
|
if (nbytes > 0) {
|
|
extract_crng(tmp);
|
|
memcpy(buf, tmp, nbytes);
|
|
crng_backtrack_protect(tmp, nbytes);
|
|
} else
|
|
crng_backtrack_protect(tmp, CHACHA20_BLOCK_SIZE);
|
|
memzero_explicit(tmp, sizeof(tmp));
|
|
}
|
|
EXPORT_SYMBOL(get_random_bytes);
|
|
|
|
/*
|
|
* Add a callback function that will be invoked when the nonblocking
|
|
* pool is initialised.
|
|
*
|
|
* returns: 0 if callback is successfully added
|
|
* -EALREADY if pool is already initialised (callback not called)
|
|
* -ENOENT if module for callback is not alive
|
|
*/
|
|
int add_random_ready_callback(struct random_ready_callback *rdy)
|
|
{
|
|
struct module *owner;
|
|
unsigned long flags;
|
|
int err = -EALREADY;
|
|
|
|
if (crng_ready())
|
|
return err;
|
|
|
|
owner = rdy->owner;
|
|
if (!try_module_get(owner))
|
|
return -ENOENT;
|
|
|
|
spin_lock_irqsave(&random_ready_list_lock, flags);
|
|
if (crng_ready())
|
|
goto out;
|
|
|
|
owner = NULL;
|
|
|
|
list_add(&rdy->list, &random_ready_list);
|
|
err = 0;
|
|
|
|
out:
|
|
spin_unlock_irqrestore(&random_ready_list_lock, flags);
|
|
|
|
module_put(owner);
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL(add_random_ready_callback);
|
|
|
|
/*
|
|
* Delete a previously registered readiness callback function.
|
|
*/
|
|
void del_random_ready_callback(struct random_ready_callback *rdy)
|
|
{
|
|
unsigned long flags;
|
|
struct module *owner = NULL;
|
|
|
|
spin_lock_irqsave(&random_ready_list_lock, flags);
|
|
if (!list_empty(&rdy->list)) {
|
|
list_del_init(&rdy->list);
|
|
owner = rdy->owner;
|
|
}
|
|
spin_unlock_irqrestore(&random_ready_list_lock, flags);
|
|
|
|
module_put(owner);
|
|
}
|
|
EXPORT_SYMBOL(del_random_ready_callback);
|
|
|
|
/*
|
|
* This function will use the architecture-specific hardware random
|
|
* number generator if it is available. The arch-specific hw RNG will
|
|
* almost certainly be faster than what we can do in software, but it
|
|
* is impossible to verify that it is implemented securely (as
|
|
* opposed, to, say, the AES encryption of a sequence number using a
|
|
* key known by the NSA). So it's useful if we need the speed, but
|
|
* only if we're willing to trust the hardware manufacturer not to
|
|
* have put in a back door.
|
|
*/
|
|
void get_random_bytes_arch(void *buf, int nbytes)
|
|
{
|
|
char *p = buf;
|
|
|
|
trace_get_random_bytes_arch(nbytes, _RET_IP_);
|
|
while (nbytes) {
|
|
unsigned long v;
|
|
int chunk = min(nbytes, (int)sizeof(unsigned long));
|
|
|
|
if (!arch_get_random_long(&v))
|
|
break;
|
|
|
|
memcpy(p, &v, chunk);
|
|
p += chunk;
|
|
nbytes -= chunk;
|
|
}
|
|
|
|
if (nbytes)
|
|
get_random_bytes(p, nbytes);
|
|
}
|
|
EXPORT_SYMBOL(get_random_bytes_arch);
|
|
|
|
|
|
/*
|
|
* init_std_data - initialize pool with system data
|
|
*
|
|
* @r: pool to initialize
|
|
*
|
|
* This function clears the pool's entropy count and mixes some system
|
|
* data into the pool to prepare it for use. The pool is not cleared
|
|
* as that can only decrease the entropy in the pool.
|
|
*/
|
|
static void init_std_data(struct entropy_store *r)
|
|
{
|
|
int i;
|
|
ktime_t now = ktime_get_real();
|
|
unsigned long rv;
|
|
|
|
r->last_pulled = jiffies;
|
|
mix_pool_bytes(r, &now, sizeof(now));
|
|
for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) {
|
|
if (!arch_get_random_seed_long(&rv) &&
|
|
!arch_get_random_long(&rv))
|
|
rv = random_get_entropy();
|
|
mix_pool_bytes(r, &rv, sizeof(rv));
|
|
}
|
|
mix_pool_bytes(r, utsname(), sizeof(*(utsname())));
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
#ifdef CONFIG_NUMA
|
|
int i;
|
|
struct crng_state *crng;
|
|
struct crng_state **pool;
|
|
#endif
|
|
|
|
init_std_data(&input_pool);
|
|
init_std_data(&blocking_pool);
|
|
crng_initialize(&primary_crng);
|
|
|
|
#ifdef CONFIG_NUMA
|
|
pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL);
|
|
for_each_online_node(i) {
|
|
crng = kmalloc_node(sizeof(struct crng_state),
|
|
GFP_KERNEL | __GFP_NOFAIL, i);
|
|
spin_lock_init(&crng->lock);
|
|
crng_initialize(crng);
|
|
pool[i] = crng;
|
|
}
|
|
mb();
|
|
crng_node_pool = pool;
|
|
#endif
|
|
return 0;
|
|
}
|
|
early_initcall(rand_initialize);
|
|
|
|
#ifdef CONFIG_BLOCK
|
|
void rand_initialize_disk(struct gendisk *disk)
|
|
{
|
|
struct timer_rand_state *state;
|
|
|
|
/*
|
|
* If kzalloc returns null, we just won't use that entropy
|
|
* source.
|
|
*/
|
|
state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
|
|
if (state) {
|
|
state->last_time = INITIAL_JIFFIES;
|
|
disk->random = state;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
static ssize_t
|
|
_random_read(int nonblock, char __user *buf, size_t nbytes)
|
|
{
|
|
ssize_t n;
|
|
|
|
if (nbytes == 0)
|
|
return 0;
|
|
|
|
nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE);
|
|
while (1) {
|
|
n = extract_entropy_user(&blocking_pool, buf, nbytes);
|
|
if (n < 0)
|
|
return n;
|
|
trace_random_read(n*8, (nbytes-n)*8,
|
|
ENTROPY_BITS(&blocking_pool),
|
|
ENTROPY_BITS(&input_pool));
|
|
if (n > 0)
|
|
return n;
|
|
|
|
/* Pool is (near) empty. Maybe wait and retry. */
|
|
if (nonblock)
|
|
return -EAGAIN;
|
|
|
|
wait_event_interruptible(random_read_wait,
|
|
ENTROPY_BITS(&input_pool) >=
|
|
random_read_wakeup_bits);
|
|
if (signal_pending(current))
|
|
return -ERESTARTSYS;
|
|
}
|
|
}
|
|
|
|
static ssize_t
|
|
random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
|
|
{
|
|
return _random_read(file->f_flags & O_NONBLOCK, buf, nbytes);
|
|
}
|
|
|
|
static ssize_t
|
|
urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
|
|
{
|
|
unsigned long flags;
|
|
static int maxwarn = 10;
|
|
int ret;
|
|
|
|
if (!crng_ready() && maxwarn > 0) {
|
|
maxwarn--;
|
|
printk(KERN_NOTICE "random: %s: uninitialized urandom read "
|
|
"(%zd bytes read)\n",
|
|
current->comm, nbytes);
|
|
spin_lock_irqsave(&primary_crng.lock, flags);
|
|
crng_init_cnt = 0;
|
|
spin_unlock_irqrestore(&primary_crng.lock, flags);
|
|
}
|
|
nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
|
|
ret = extract_crng_user(buf, nbytes);
|
|
trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool));
|
|
return ret;
|
|
}
|
|
|
|
static unsigned int
|
|
random_poll(struct file *file, poll_table * wait)
|
|
{
|
|
unsigned int mask;
|
|
|
|
poll_wait(file, &random_read_wait, wait);
|
|
poll_wait(file, &random_write_wait, wait);
|
|
mask = 0;
|
|
if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits)
|
|
mask |= POLLIN | POLLRDNORM;
|
|
if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits)
|
|
mask |= POLLOUT | POLLWRNORM;
|
|
return mask;
|
|
}
|
|
|
|
static int
|
|
write_pool(struct entropy_store *r, const char __user *buffer, size_t count)
|
|
{
|
|
size_t bytes;
|
|
__u32 buf[16];
|
|
const char __user *p = buffer;
|
|
|
|
while (count > 0) {
|
|
bytes = min(count, sizeof(buf));
|
|
if (copy_from_user(&buf, p, bytes))
|
|
return -EFAULT;
|
|
|
|
count -= bytes;
|
|
p += bytes;
|
|
|
|
mix_pool_bytes(r, buf, bytes);
|
|
cond_resched();
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t random_write(struct file *file, const char __user *buffer,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
size_t ret;
|
|
|
|
ret = write_pool(&input_pool, buffer, count);
|
|
if (ret)
|
|
return ret;
|
|
|
|
return (ssize_t)count;
|
|
}
|
|
|
|
static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
|
|
{
|
|
int size, ent_count;
|
|
int __user *p = (int __user *)arg;
|
|
int retval;
|
|
|
|
switch (cmd) {
|
|
case RNDGETENTCNT:
|
|
/* inherently racy, no point locking */
|
|
ent_count = ENTROPY_BITS(&input_pool);
|
|
if (put_user(ent_count, p))
|
|
return -EFAULT;
|
|
return 0;
|
|
case RNDADDTOENTCNT:
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
if (get_user(ent_count, p))
|
|
return -EFAULT;
|
|
return credit_entropy_bits_safe(&input_pool, ent_count);
|
|
case RNDADDENTROPY:
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
if (get_user(ent_count, p++))
|
|
return -EFAULT;
|
|
if (ent_count < 0)
|
|
return -EINVAL;
|
|
if (get_user(size, p++))
|
|
return -EFAULT;
|
|
retval = write_pool(&input_pool, (const char __user *)p,
|
|
size);
|
|
if (retval < 0)
|
|
return retval;
|
|
return credit_entropy_bits_safe(&input_pool, ent_count);
|
|
case RNDZAPENTCNT:
|
|
case RNDCLEARPOOL:
|
|
/*
|
|
* Clear the entropy pool counters. We no longer clear
|
|
* the entropy pool, as that's silly.
|
|
*/
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
input_pool.entropy_count = 0;
|
|
blocking_pool.entropy_count = 0;
|
|
return 0;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
static int random_fasync(int fd, struct file *filp, int on)
|
|
{
|
|
return fasync_helper(fd, filp, on, &fasync);
|
|
}
|
|
|
|
const struct file_operations random_fops = {
|
|
.read = random_read,
|
|
.write = random_write,
|
|
.poll = random_poll,
|
|
.unlocked_ioctl = random_ioctl,
|
|
.fasync = random_fasync,
|
|
.llseek = noop_llseek,
|
|
};
|
|
|
|
const struct file_operations urandom_fops = {
|
|
.read = urandom_read,
|
|
.write = random_write,
|
|
.unlocked_ioctl = random_ioctl,
|
|
.fasync = random_fasync,
|
|
.llseek = noop_llseek,
|
|
};
|
|
|
|
SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
|
|
unsigned int, flags)
|
|
{
|
|
if (flags & ~(GRND_NONBLOCK|GRND_RANDOM))
|
|
return -EINVAL;
|
|
|
|
if (count > INT_MAX)
|
|
count = INT_MAX;
|
|
|
|
if (flags & GRND_RANDOM)
|
|
return _random_read(flags & GRND_NONBLOCK, buf, count);
|
|
|
|
if (!crng_ready()) {
|
|
if (flags & GRND_NONBLOCK)
|
|
return -EAGAIN;
|
|
crng_wait_ready();
|
|
if (signal_pending(current))
|
|
return -ERESTARTSYS;
|
|
}
|
|
return urandom_read(NULL, buf, count, NULL);
|
|
}
|
|
|
|
/********************************************************************
|
|
*
|
|
* Sysctl interface
|
|
*
|
|
********************************************************************/
|
|
|
|
#ifdef CONFIG_SYSCTL
|
|
|
|
#include <linux/sysctl.h>
|
|
|
|
static int min_read_thresh = 8, min_write_thresh;
|
|
static int max_read_thresh = OUTPUT_POOL_WORDS * 32;
|
|
static int max_write_thresh = INPUT_POOL_WORDS * 32;
|
|
static int random_min_urandom_seed = 60;
|
|
static char sysctl_bootid[16];
|
|
|
|
/*
|
|
* This function is used to return both the bootid UUID, and random
|
|
* UUID. The difference is in whether table->data is NULL; if it is,
|
|
* then a new UUID is generated and returned to the user.
|
|
*
|
|
* If the user accesses this via the proc interface, the UUID will be
|
|
* returned as an ASCII string in the standard UUID format; if via the
|
|
* sysctl system call, as 16 bytes of binary data.
|
|
*/
|
|
static int proc_do_uuid(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
struct ctl_table fake_table;
|
|
unsigned char buf[64], tmp_uuid[16], *uuid;
|
|
|
|
uuid = table->data;
|
|
if (!uuid) {
|
|
uuid = tmp_uuid;
|
|
generate_random_uuid(uuid);
|
|
} else {
|
|
static DEFINE_SPINLOCK(bootid_spinlock);
|
|
|
|
spin_lock(&bootid_spinlock);
|
|
if (!uuid[8])
|
|
generate_random_uuid(uuid);
|
|
spin_unlock(&bootid_spinlock);
|
|
}
|
|
|
|
sprintf(buf, "%pU", uuid);
|
|
|
|
fake_table.data = buf;
|
|
fake_table.maxlen = sizeof(buf);
|
|
|
|
return proc_dostring(&fake_table, write, buffer, lenp, ppos);
|
|
}
|
|
|
|
/*
|
|
* Return entropy available scaled to integral bits
|
|
*/
|
|
static int proc_do_entropy(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
struct ctl_table fake_table;
|
|
int entropy_count;
|
|
|
|
entropy_count = *(int *)table->data >> ENTROPY_SHIFT;
|
|
|
|
fake_table.data = &entropy_count;
|
|
fake_table.maxlen = sizeof(entropy_count);
|
|
|
|
return proc_dointvec(&fake_table, write, buffer, lenp, ppos);
|
|
}
|
|
|
|
static int sysctl_poolsize = INPUT_POOL_WORDS * 32;
|
|
extern struct ctl_table random_table[];
|
|
struct ctl_table random_table[] = {
|
|
{
|
|
.procname = "poolsize",
|
|
.data = &sysctl_poolsize,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0444,
|
|
.proc_handler = proc_dointvec,
|
|
},
|
|
{
|
|
.procname = "entropy_avail",
|
|
.maxlen = sizeof(int),
|
|
.mode = 0444,
|
|
.proc_handler = proc_do_entropy,
|
|
.data = &input_pool.entropy_count,
|
|
},
|
|
{
|
|
.procname = "read_wakeup_threshold",
|
|
.data = &random_read_wakeup_bits,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_minmax,
|
|
.extra1 = &min_read_thresh,
|
|
.extra2 = &max_read_thresh,
|
|
},
|
|
{
|
|
.procname = "write_wakeup_threshold",
|
|
.data = &random_write_wakeup_bits,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec_minmax,
|
|
.extra1 = &min_write_thresh,
|
|
.extra2 = &max_write_thresh,
|
|
},
|
|
{
|
|
.procname = "urandom_min_reseed_secs",
|
|
.data = &random_min_urandom_seed,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec,
|
|
},
|
|
{
|
|
.procname = "boot_id",
|
|
.data = &sysctl_bootid,
|
|
.maxlen = 16,
|
|
.mode = 0444,
|
|
.proc_handler = proc_do_uuid,
|
|
},
|
|
{
|
|
.procname = "uuid",
|
|
.maxlen = 16,
|
|
.mode = 0444,
|
|
.proc_handler = proc_do_uuid,
|
|
},
|
|
#ifdef ADD_INTERRUPT_BENCH
|
|
{
|
|
.procname = "add_interrupt_avg_cycles",
|
|
.data = &avg_cycles,
|
|
.maxlen = sizeof(avg_cycles),
|
|
.mode = 0444,
|
|
.proc_handler = proc_doulongvec_minmax,
|
|
},
|
|
{
|
|
.procname = "add_interrupt_avg_deviation",
|
|
.data = &avg_deviation,
|
|
.maxlen = sizeof(avg_deviation),
|
|
.mode = 0444,
|
|
.proc_handler = proc_doulongvec_minmax,
|
|
},
|
|
#endif
|
|
{ }
|
|
};
|
|
#endif /* CONFIG_SYSCTL */
|
|
|
|
struct batched_entropy {
|
|
union {
|
|
u64 entropy_u64[CHACHA20_BLOCK_SIZE / sizeof(u64)];
|
|
u32 entropy_u32[CHACHA20_BLOCK_SIZE / sizeof(u32)];
|
|
};
|
|
unsigned int position;
|
|
};
|
|
static rwlock_t batched_entropy_reset_lock = __RW_LOCK_UNLOCKED(batched_entropy_reset_lock);
|
|
|
|
/*
|
|
* Get a random word for internal kernel use only. The quality of the random
|
|
* number is either as good as RDRAND or as good as /dev/urandom, with the
|
|
* goal of being quite fast and not depleting entropy.
|
|
*/
|
|
static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64);
|
|
u64 get_random_u64(void)
|
|
{
|
|
u64 ret;
|
|
bool use_lock = READ_ONCE(crng_init) < 2;
|
|
unsigned long flags = 0;
|
|
struct batched_entropy *batch;
|
|
|
|
#if BITS_PER_LONG == 64
|
|
if (arch_get_random_long((unsigned long *)&ret))
|
|
return ret;
|
|
#else
|
|
if (arch_get_random_long((unsigned long *)&ret) &&
|
|
arch_get_random_long((unsigned long *)&ret + 1))
|
|
return ret;
|
|
#endif
|
|
|
|
batch = &get_cpu_var(batched_entropy_u64);
|
|
if (use_lock)
|
|
read_lock_irqsave(&batched_entropy_reset_lock, flags);
|
|
if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
|
|
extract_crng((u8 *)batch->entropy_u64);
|
|
batch->position = 0;
|
|
}
|
|
ret = batch->entropy_u64[batch->position++];
|
|
if (use_lock)
|
|
read_unlock_irqrestore(&batched_entropy_reset_lock, flags);
|
|
put_cpu_var(batched_entropy_u64);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(get_random_u64);
|
|
|
|
static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32);
|
|
u32 get_random_u32(void)
|
|
{
|
|
u32 ret;
|
|
bool use_lock = READ_ONCE(crng_init) < 2;
|
|
unsigned long flags = 0;
|
|
struct batched_entropy *batch;
|
|
|
|
if (arch_get_random_int(&ret))
|
|
return ret;
|
|
|
|
batch = &get_cpu_var(batched_entropy_u32);
|
|
if (use_lock)
|
|
read_lock_irqsave(&batched_entropy_reset_lock, flags);
|
|
if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
|
|
extract_crng((u8 *)batch->entropy_u32);
|
|
batch->position = 0;
|
|
}
|
|
ret = batch->entropy_u32[batch->position++];
|
|
if (use_lock)
|
|
read_unlock_irqrestore(&batched_entropy_reset_lock, flags);
|
|
put_cpu_var(batched_entropy_u32);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(get_random_u32);
|
|
|
|
/* It's important to invalidate all potential batched entropy that might
|
|
* be stored before the crng is initialized, which we can do lazily by
|
|
* simply resetting the counter to zero so that it's re-extracted on the
|
|
* next usage. */
|
|
static void invalidate_batched_entropy(void)
|
|
{
|
|
int cpu;
|
|
unsigned long flags;
|
|
|
|
write_lock_irqsave(&batched_entropy_reset_lock, flags);
|
|
for_each_possible_cpu (cpu) {
|
|
per_cpu_ptr(&batched_entropy_u32, cpu)->position = 0;
|
|
per_cpu_ptr(&batched_entropy_u64, cpu)->position = 0;
|
|
}
|
|
write_unlock_irqrestore(&batched_entropy_reset_lock, flags);
|
|
}
|
|
|
|
/**
|
|
* randomize_page - Generate a random, page aligned address
|
|
* @start: The smallest acceptable address the caller will take.
|
|
* @range: The size of the area, starting at @start, within which the
|
|
* random address must fall.
|
|
*
|
|
* If @start + @range would overflow, @range is capped.
|
|
*
|
|
* NOTE: Historical use of randomize_range, which this replaces, presumed that
|
|
* @start was already page aligned. We now align it regardless.
|
|
*
|
|
* Return: A page aligned address within [start, start + range). On error,
|
|
* @start is returned.
|
|
*/
|
|
unsigned long
|
|
randomize_page(unsigned long start, unsigned long range)
|
|
{
|
|
if (!PAGE_ALIGNED(start)) {
|
|
range -= PAGE_ALIGN(start) - start;
|
|
start = PAGE_ALIGN(start);
|
|
}
|
|
|
|
if (start > ULONG_MAX - range)
|
|
range = ULONG_MAX - start;
|
|
|
|
range >>= PAGE_SHIFT;
|
|
|
|
if (range == 0)
|
|
return start;
|
|
|
|
return start + (get_random_long() % range << PAGE_SHIFT);
|
|
}
|
|
|
|
/* Interface for in-kernel drivers of true hardware RNGs.
|
|
* Those devices may produce endless random bits and will be throttled
|
|
* when our pool is full.
|
|
*/
|
|
void add_hwgenerator_randomness(const char *buffer, size_t count,
|
|
size_t entropy)
|
|
{
|
|
struct entropy_store *poolp = &input_pool;
|
|
|
|
if (!crng_ready()) {
|
|
crng_fast_load(buffer, count);
|
|
return;
|
|
}
|
|
|
|
/* Suspend writing if we're above the trickle threshold.
|
|
* We'll be woken up again once below random_write_wakeup_thresh,
|
|
* or when the calling thread is about to terminate.
|
|
*/
|
|
wait_event_interruptible(random_write_wait, kthread_should_stop() ||
|
|
ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);
|
|
mix_pool_bytes(poolp, buffer, count);
|
|
credit_entropy_bits(poolp, entropy);
|
|
}
|
|
EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
|