cregit-Linux how code gets into the kernel

Release 4.11 drivers/char/random.c

Directory: drivers/char
/*
 * random.c -- A strong random number generator
 *
 * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005
 *
 * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999.  All
 * rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, and the entire permission notice in its entirety,
 *    including the disclaimer of warranties.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior
 *    written permission.
 *
 * ALTERNATIVELY, this product may be distributed under the terms of
 * the GNU General Public License, in which case the provisions of the GPL are
 * required INSTEAD OF the above restrictions.  (This clause is
 * necessary due to a potential bad interaction between the GPL and
 * the restrictions contained in a BSD-style copyright.)
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
 * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */

/*
 * (now, with legal B.S. out of the way.....)
 *
 * This routine gathers environmental noise from device drivers, etc.,
 * and returns good random numbers, suitable for cryptographic use.
 * Besides the obvious cryptographic uses, these numbers are also good
 * for seeding TCP sequence numbers, and other places where it is
 * desirable to have numbers which are not only random, but hard to
 * predict by an attacker.
 *
 * Theory of operation
 * ===================
 *
 * Computers are very predictable devices.  Hence it is extremely hard
 * to produce truly random numbers on a computer --- as opposed to
 * pseudo-random numbers, which can easily generated by using a
 * algorithm.  Unfortunately, it is very easy for attackers to guess
 * the sequence of pseudo-random number generators, and for some
 * applications this is not acceptable.  So instead, we must try to
 * gather "environmental noise" from the computer's environment, which
 * must be hard for outside attackers to observe, and use that to
 * generate random numbers.  In a Unix environment, this is best done
 * from inside the kernel.
 *
 * Sources of randomness from the environment include inter-keyboard
 * timings, inter-interrupt timings from some interrupts, and other
 * events which are both (a) non-deterministic and (b) hard for an
 * outside observer to measure.  Randomness from these sources are
 * added to an "entropy pool", which is mixed using a CRC-like function.
 * This is not cryptographically strong, but it is adequate assuming
 * the randomness is not chosen maliciously, and it is fast enough that
 * the overhead of doing it on every interrupt is very reasonable.
 * As random bytes are mixed into the entropy pool, the routines keep
 * an *estimate* of how many bits of randomness have been stored into
 * the random number generator's internal state.
 *
 * When random bytes are desired, they are obtained by taking the SHA
 * hash of the contents of the "entropy pool".  The SHA hash avoids
 * exposing the internal state of the entropy pool.  It is believed to
 * be computationally infeasible to derive any useful information
 * about the input of SHA from its output.  Even if it is possible to
 * analyze SHA in some clever way, as long as the amount of data
 * returned from the generator is less than the inherent entropy in
 * the pool, the output data is totally unpredictable.  For this
 * reason, the routine decreases its internal estimate of how many
 * bits of "true randomness" are contained in the entropy pool as it
 * outputs random numbers.
 *
 * If this estimate goes to zero, the routine can still generate
 * random numbers; however, an attacker may (at least in theory) be
 * able to infer the future output of the generator from prior
 * outputs.  This requires successful cryptanalysis of SHA, which is
 * not believed to be feasible, but there is a remote possibility.
 * Nonetheless, these numbers should be useful for the vast majority
 * of purposes.
 *
 * Exported interfaces ---- output
 * ===============================
 *
 * There are three exported interfaces; the first is one designed to
 * be used from within the kernel:
 *
 *      void get_random_bytes(void *buf, int nbytes);
 *
 * This interface will return the requested number of random bytes,
 * and place it in the requested buffer.
 *
 * The two other interfaces are two character devices /dev/random and
 * /dev/urandom.  /dev/random is suitable for use when very high
 * quality randomness is desired (for example, for key generation or
 * one-time pads), as it will only return a maximum of the number of
 * bits of randomness (as estimated by the random number generator)
 * contained in the entropy pool.
 *
 * The /dev/urandom device does not have this limit, and will return
 * as many bytes as are requested.  As more and more random bytes are
 * requested without giving time for the entropy pool to recharge,
 * this will result in random numbers that are merely cryptographically
 * strong.  For many applications, however, this is acceptable.
 *
 * Exported interfaces ---- input
 * ==============================
 *
 * The current exported interfaces for gathering environmental noise
 * from the devices are:
 *
 *      void add_device_randomness(const void *buf, unsigned int size);
 *      void add_input_randomness(unsigned int type, unsigned int code,
 *                                unsigned int value);
 *      void add_interrupt_randomness(int irq, int irq_flags);
 *      void add_disk_randomness(struct gendisk *disk);
 *
 * add_device_randomness() is for adding data to the random pool that
 * is likely to differ between two devices (or possibly even per boot).
 * This would be things like MAC addresses or serial numbers, or the
 * read-out of the RTC. This does *not* add any actual entropy to the
 * pool, but it initializes the pool to different values for devices
 * that might otherwise be identical and have very little entropy
 * available to them (particularly common in the embedded world).
 *
 * add_input_randomness() uses the input layer interrupt timing, as well as
 * the event type information from the hardware.
 *
 * add_interrupt_randomness() uses the interrupt timing as random
 * inputs to the entropy pool. Using the cycle counters and the irq source
 * as inputs, it feeds the randomness roughly once a second.
 *
 * add_disk_randomness() uses what amounts to the seek time of block
 * layer request events, on a per-disk_devt basis, as input to the
 * entropy pool. Note that high-speed solid state drives with very low
 * seek times do not make for good sources of entropy, as their seek
 * times are usually fairly consistent.
 *
 * All of these routines try to estimate how many bits of randomness a
 * particular randomness source.  They do this by keeping track of the
 * first and second order deltas of the event timings.
 *
 * Ensuring unpredictability at system startup
 * ============================================
 *
 * When any operating system starts up, it will go through a sequence
 * of actions that are fairly predictable by an adversary, especially
 * if the start-up does not involve interaction with a human operator.
 * This reduces the actual number of bits of unpredictability in the
 * entropy pool below the value in entropy_count.  In order to
 * counteract this effect, it helps to carry information in the
 * entropy pool across shut-downs and start-ups.  To do this, put the
 * following lines an appropriate script which is run during the boot
 * sequence:
 *
 *      echo "Initializing random number generator..."
 *      random_seed=/var/run/random-seed
 *      # Carry a random seed from start-up to start-up
 *      # Load and then save the whole entropy pool
 *      if [ -f $random_seed ]; then
 *              cat $random_seed >/dev/urandom
 *      else
 *              touch $random_seed
 *      fi
 *      chmod 600 $random_seed
 *      dd if=/dev/urandom of=$random_seed count=1 bs=512
 *
 * and the following lines in an appropriate script which is run as
 * the system is shutdown:
 *
 *      # Carry a random seed from shut-down to start-up
 *      # Save the whole entropy pool
 *      echo "Saving random seed..."
 *      random_seed=/var/run/random-seed
 *      touch $random_seed
 *      chmod 600 $random_seed
 *      dd if=/dev/urandom of=$random_seed count=1 bs=512
 *
 * For example, on most modern systems using the System V init
 * scripts, such code fragments would be found in
 * /etc/rc.d/init.d/random.  On older Linux systems, the correct script
 * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0.
 *
 * Effectively, these commands cause the contents of the entropy pool
 * to be saved at shut-down time and reloaded into the entropy pool at
 * start-up.  (The 'dd' in the addition to the bootup script is to
 * make sure that /etc/random-seed is different for every start-up,
 * even if the system crashes without executing rc.0.)  Even with
 * complete knowledge of the start-up activities, predicting the state
 * of the entropy pool requires knowledge of the previous history of
 * the system.
 *
 * Configuring the /dev/random driver under Linux
 * ==============================================
 *
 * The /dev/random driver under Linux uses minor numbers 8 and 9 of
 * the /dev/mem major number (#1).  So if your system does not have
 * /dev/random and /dev/urandom created already, they can be created
 * by using the commands:
 *
 *      mknod /dev/random c 1 8
 *      mknod /dev/urandom c 1 9
 *
 * Acknowledgements:
 * =================
 *
 * Ideas for constructing this random number generator were derived
 * from Pretty Good Privacy's random number generator, and from private
 * discussions with Phil Karn.  Colin Plumb provided a faster random
 * number generator, which speed up the mixing function of the entropy
 * pool, taken from PGPfone.  Dale Worley has also contributed many
 * useful ideas and suggestions to improve this driver.
 *
 * Any flaws in the design are solely my responsibility, and should
 * not be attributed to the Phil, Colin, or any of authors of PGP.
 *
 * Further background information on this topic may be obtained from
 * RFC 1750, "Randomness Recommendations for Security", by Donald
 * Eastlake, Steve Crocker, and Jeff Schiller.
 */

#include <linux/utsname.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/genhd.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/nodemask.h>
#include <linux/spinlock.h>
#include <linux/kthread.h>
#include <linux/percpu.h>
#include <linux/cryptohash.h>
#include <linux/fips.h>
#include <linux/ptrace.h>
#include <linux/kmemcheck.h>
#include <linux/workqueue.h>
#include <linux/irq.h>
#include <linux/syscalls.h>
#include <linux/completion.h>
#include <linux/uuid.h>
#include <crypto/chacha20.h>

#include <asm/processor.h>
#include <linux/uaccess.h>
#include <asm/irq.h>
#include <asm/irq_regs.h>
#include <asm/io.h>


#define CREATE_TRACE_POINTS
#include <trace/events/random.h>

/* #define ADD_INTERRUPT_BENCH */

/*
 * Configuration information
 */

#define INPUT_POOL_SHIFT	12

#define INPUT_POOL_WORDS	(1 << (INPUT_POOL_SHIFT-5))

#define OUTPUT_POOL_SHIFT	10

#define OUTPUT_POOL_WORDS	(1 << (OUTPUT_POOL_SHIFT-5))

#define SEC_XFER_SIZE		512

#define EXTRACT_SIZE		10


#define DEBUG_RANDOM_BOOT 0


#define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long))

/*
 * To allow fractional bits to be tracked, the entropy_count field is
 * denominated in units of 1/8th bits.
 *
 * 2*(ENTROPY_SHIFT + log2(poolbits)) must <= 31, or the multiply in
 * credit_entropy_bits() needs to be 64 bits wide.
 */

#define ENTROPY_SHIFT 3

#define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT)

/*
 * The minimum number of bits of entropy before we wake up a read on
 * /dev/random.  Should be enough to do a significant reseed.
 */

static int random_read_wakeup_bits = 64;

/*
 * If the entropy count falls under this number of bits, then we
 * should wake up processes which are selecting or polling on write
 * access to /dev/random.
 */

static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS;

/*
 * Originally, we used a primitive polynomial of degree .poolwords
 * over GF(2).  The taps for various sizes are defined below.  They
 * were chosen to be evenly spaced except for the last tap, which is 1
 * to get the twisting happening as fast as possible.
 *
 * For the purposes of better mixing, we use the CRC-32 polynomial as
 * well to make a (modified) twisted Generalized Feedback Shift
 * Register.  (See M. Matsumoto & Y. Kurita, 1992.  Twisted GFSR
 * generators.  ACM Transactions on Modeling and Computer Simulation
 * 2(3):179-194.  Also see M. Matsumoto & Y. Kurita, 1994.  Twisted
 * GFSR generators II.  ACM Transactions on Modeling and Computer
 * Simulation 4:254-266)
 *
 * Thanks to Colin Plumb for suggesting this.
 *
 * The mixing operation is much less sensitive than the output hash,
 * where we use SHA-1.  All that we want of mixing operation is that
 * it be a good non-cryptographic hash; i.e. it not produce collisions
 * when fed "random" data of the sort we expect to see.  As long as
 * the pool state differs for different inputs, we have preserved the
 * input entropy and done a good job.  The fact that an intelligent
 * attacker can construct inputs that will produce controlled
 * alterations to the pool's state is not important because we don't
 * consider such inputs to contribute any randomness.  The only
 * property we need with respect to them is that the attacker can't
 * increase his/her knowledge of the pool's state.  Since all
 * additions are reversible (knowing the final state and the input,
 * you can reconstruct the initial state), if an attacker has any
 * uncertainty about the initial state, he/she can only shuffle that
 * uncertainty about, but never cause any collisions (which would
 * decrease the uncertainty).
 *
 * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and
 * Videau in their paper, "The Linux Pseudorandom Number Generator
 * Revisited" (see: http://eprint.iacr.org/2012/251.pdf).  In their
 * paper, they point out that we are not using a true Twisted GFSR,
 * since Matsumoto & Kurita used a trinomial feedback polynomial (that
 * is, with only three taps, instead of the six that we are using).
 * As a result, the resulting polynomial is neither primitive nor
 * irreducible, and hence does not have a maximal period over
 * GF(2**32).  They suggest a slight change to the generator
 * polynomial which improves the resulting TGFSR polynomial to be
 * irreducible, which we have made here.
 */

static struct poolinfo {
	




int poolbitshift, poolwords, poolbytes, poolbits, poolfracbits;

#define S(x) ilog2(x)+5, (x), (x)*4, (x)*32, (x) << (ENTROPY_SHIFT+5)
	




int tap1, tap2, tap3, tap4, tap5;
} 
poolinfo_table[] = {
	/* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */
	/* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */
	{ S(128),	104,	76,	51,	25,	1 },
	/* was: x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 */
	/* x^32 + x^26 + x^19 + x^14 + x^7 + x + 1 */
	{ S(32),	26,	19,	14,	7,	1 },
#if 0
	/* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1  -- 115 */
	{ S(2048),      1638,   1231,   819,    411,    1 },

	/* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */
	{ S(1024),      817,    615,    412,    204,    1 },

	/* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */
	{ S(1024),      819,    616,    410,    207,    2 },

	/* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */
	{ S(512),       411,    308,    208,    104,    1 },

	/* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */
	{ S(512),       409,    307,    206,    102,    2 },
	/* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */
	{ S(512),       409,    309,    205,    103,    2 },

	/* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */
	{ S(256),       205,    155,    101,    52,     1 },

	/* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */
	{ S(128),       103,    78,     51,     27,     2 },

	/* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */
	{ S(64),        52,     39,     26,     14,     1 },
#endif
};

/*
 * Static global variables
 */
static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);

static struct fasync_struct *fasync;

static DEFINE_SPINLOCK(random_ready_list_lock);
static LIST_HEAD(random_ready_list);


struct crng_state {
	
__u32		state[16];
	
unsigned long	init_time;
	
spinlock_t	lock;
};


struct crng_state primary_crng = {
	.lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock),
};

/*
 * crng_init =  0 --> Uninitialized
 *              1 --> Initialized
 *              2 --> Initialized from input_pool
 *
 * crng_init is protected by primary_crng->lock, and only increases
 * its value (from 0->1->2).
 */

static int crng_init = 0;

#define crng_ready() (likely(crng_init > 0))

static int crng_init_cnt = 0;

#define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE)
static void _extract_crng(struct crng_state *crng,
			  __u8 out[CHACHA20_BLOCK_SIZE]);
static void _crng_backtrack_protect(struct crng_state *crng,
				    __u8 tmp[CHACHA20_BLOCK_SIZE], int used);
static void process_random_ready_list(void);

/**********************************************************************
 *
 * 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 };

/*
 * 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.
 *
 * 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;
	tap2 = r->poolinfo->tap2;
	tap3 = r->poolinfo->tap3;
	tap4 = r->poolinfo->tap4;
	tap5 = r->poolinfo->tap5;

	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;
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)13248.35%529.41%


Andrew Morton6925.27%15.88%


Matt Mackall4616.85%847.06%


Linus Torvalds165.86%15.88%


Theodore Y. Ts'o103.66%211.76%


Total273100.00%17100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o39100.00%1100.00%


Total39100.00%1100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o3860.32%250.00%


Matt Mackall2539.68%250.00%


Total63100.00%4100.00%




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;

	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++;
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o21896.46%375.00%


George Spelvin83.54%125.00%


Total226100.00%4100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
Herbert Xu77100.00%1100.00%


Total77100.00%1100.00%



/*
 * 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;
			}
		}
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o17645.01%626.09%


H. Peter Anvin11228.64%28.70%


Matt Mackall4712.02%313.04%


Linus Torvalds143.58%28.70%


Andrew Morton143.58%28.70%


Jeff Dike112.81%14.35%


Linus Torvalds (pre-git)71.79%313.04%


Greg Price61.53%28.70%


Hannes Frederic Sowa41.02%28.70%


Total391100.00%23100.00%






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;
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o62100.00%2100.00%


Total62100.00%2100.00%



/*********************************************************************
 *
 * 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 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;
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o13598.54%375.00%


Hannes Frederic Sowa21.46%125.00%


Total137100.00%4100.00%






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--;
	}
	if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
		crng_init = 1;
		wake_up_interruptible(&crng_init_wait);
		pr_notice("random: fast init done\n");
	}
	spin_unlock_irqrestore(&primary_crng.lock, flags);
	return 1;
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o140100.00%1100.00%


Total140100.00%1100.00%






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;
	if (crng == &primary_crng && crng_init < 2) {
		crng_init = 2;
		process_random_ready_list();
		wake_up_interruptible(&crng_init_wait);
		pr_notice("random: crng init done\n");
	}
	spin_unlock_irqrestore(&primary_crng.lock, flags);
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o222100.00%3100.00%


Total222100.00%3100.00%






static inline void crng_wait_ready(void)
{
	wait_event_interruptible(crng_init_wait, crng_ready());
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o17100.00%1100.00%


Total17100.00%1100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o12298.39%466.67%


Linus Torvalds (pre-git)10.81%116.67%


Hannes Frederic Sowa10.81%116.67%


Total124100.00%6100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o54100.00%1100.00%


Total54100.00%1100.00%



/*
 * 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);
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o128100.00%1100.00%


Total128100.00%1100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o59100.00%1100.00%


Total59100.00%1100.00%






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;
}



Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o12082.76%240.00%


H. Peter Anvin1611.03%120.00%


Jeff Dike74.83%120.00%


Matt Mackall21.38%120.00%


Total145100.00%5100.00%



/*********************************************************************
 *
 * 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;

	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);
}

Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds4456.41%125.00%


Theodore Y. Ts'o3443.59%375.00%


Total78100.00%4100.00%




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();
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)13061.32%640.00%


Matt Mackall5827.36%320.00%


Theodore Y. Ts'o136.13%213.33%


Ingo Molnar62.83%16.67%


Linus Torvalds31.42%16.67%


Brian Gerst10.47%16.67%


Anton Blanchard10.47%16.67%


Total212100.00%15100.00%






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));
}

Contributors
PersonTokensPropCommitsCommitProp
Matt Mackall3756.92%114.29%


Linus Torvalds (pre-git)1523.08%457.14%


Theodore Y. Ts'o913.85%114.29%


Brian Gerst46.15%114.29%


Total65100.00%7100.00%




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;
}

Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o58100.00%1100.00%


Total58100.00%1100.00%



#else

#define add_interrupt_bench(x)
#endif




static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
{
	__u32 *ptr = (__u32 *) regs;

	if (regs == NULL)
		return 0;
	if (f->reg_idx >= sizeof(struct pt_regs) / sizeof(__u32))
		f->reg_idx = 0;
	return *(ptr + f->reg_idx++);
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o69100.00%1100.00%


Total69100.00%1100.00%






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);
}

Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o29882.78%960.00%


H. Peter Anvin349.44%16.67%


Linus Torvalds (pre-git)164.44%213.33%


Yinghai Lu61.67%16.67%


Matt Mackall41.11%16.67%


Christoph Lameter20.56%16.67%


Total360100.00%15100.00%




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));
}

Contributors
PersonTokensPropCommitsCommitProp
Al Viro1530.00%114.29%


Linus Torvalds (pre-git)1224.00%342.86%


Theodore Y. Ts'o1122.00%114.29%


Tejun Heo816.00%114.29%


Matt Mackall48.00%114.29%


Total50100.00%7100.00%




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);
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o3871.70%250.00%


Matt Mackall1018.87%125.00%


Linus Torvalds (pre-git)59.43%125.00%


Total53100.00%4100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
Matt Mackall4235.59%743.75%


Theodore Y. Ts'o2823.73%212.50%


Linus Torvalds (pre-git)2117.80%318.75%


Linus Torvalds1512.71%16.25%


Andrew Morton86.78%16.25%


Greg Price32.54%16.25%


Stephan Mueller10.85%16.25%


Total118100.00%16100.00%



/*
 * 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);
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o6096.77%133.33%


Greg Price11.61%133.33%


Linus Torvalds (pre-git)11.61%133.33%


Total62100.00%3100.00%



/*
 * 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;
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o5523.61%420.00%


Hannes Frederic Sowa4519.31%15.00%


Linus Torvalds (pre-git)3414.59%210.00%


H. Peter Anvin2912.45%15.00%


Greg Price2812.02%315.00%


Matt Mackall156.44%420.00%


Jiri Kosina146.01%15.00%


Andrew Morton73.00%210.00%


Stephan Mueller52.15%15.00%


Linus Torvalds10.43%15.00%


Total233100.00%20100.00%



/*
 * 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));
}


Contributors
PersonTokensPropCommitsCommitProp
Matt Mackall10340.55%1365.00%


Theodore Y. Ts'o6927.17%315.00%


Linus Torvalds (pre-git)4116.14%210.00%


H. Peter Anvin3915.35%15.00%


Daniel Borkmann20.79%15.00%


Total254100.00%20100.00%






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;
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o7649.67%233.33%


Matt Mackall4026.14%233.33%


Jarod Wilson3724.18%233.33%


Total153100.00%6100.00%



/*
 * 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);
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o8948.11%111.11%


Jarod Wilson4725.41%222.22%


Neil Horman2815.14%111.11%


Linus Torvalds (pre-git)94.86%222.22%


Matt Mackall94.86%222.22%


H. Peter Anvin31.62%111.11%


Total185100.00%9100.00%



/*
 * 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;
}


Contributors
PersonTokensPropCommitsCommitProp
Matt Mackall10659.22%225.00%


Linus Torvalds (pre-git)4525.14%225.00%


Theodore Y. Ts'o2413.41%225.00%


H. Peter Anvin31.68%112.50%


Daniel Borkmann10.56%112.50%


Total179100.00%8100.00%



/*
 * 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));
}

Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o11090.91%583.33%


Linus Torvalds (pre-git)119.09%116.67%


Total121100.00%6100.00%




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;
}

Contributors
PersonTokensPropCommitsCommitProp
Herbert Xu10096.15%150.00%


Theodore Y. Ts'o43.85%150.00%


Total104100.00%2100.00%




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);
}

Contributors
PersonTokensPropCommitsCommitProp
Herbert Xu69100.00%1100.00%


Total69100.00%1100.00%




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);
}

Contributors
PersonTokensPropCommitsCommitProp
H. Peter Anvin6167.03%112.50%


Theodore Y. Ts'o2325.27%450.00%


Linus Torvalds (pre-git)66.59%225.00%


Tony Luck11.10%112.50%


Total91100.00%8100.00%




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())));
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o5446.15%426.67%


Linus Torvalds (pre-git)3126.50%320.00%


H. Peter Anvin1210.26%320.00%


Matt Mackall75.98%213.33%


Serge E. Hallyn75.98%16.67%


Eric Dumazet43.42%16.67%


Jarod Wilson21.71%16.67%


Total117100.00%15100.00%



/*
 * 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;
}

Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o8974.17%325.00%


Linus Torvalds (pre-git)108.33%325.00%


Bálint Márton75.83%216.67%


Andrew Morton54.17%18.33%


Matt Mackall54.17%216.67%


Michael Ellerman43.33%18.33%


Total120100.00%12100.00%




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;
	}
}

Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)2859.57%350.00%


Al Viro919.15%116.67%


Theodore Y. Ts'o817.02%116.67%


Eric Dumazet24.26%116.67%


Total47100.00%6100.00%



#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;
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)4633.82%423.53%


Andrew Morton2316.91%15.88%


Greg Price2316.91%211.76%


Theodore Y. Ts'o1712.50%211.76%


Matt Mackall128.82%423.53%


H. Peter Anvin75.15%211.76%


Jiri Kosina75.15%15.88%


Al Viro10.74%15.88%


Total136100.00%17100.00%





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);
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o2670.27%133.33%


Linus Torvalds (pre-git)924.32%133.33%


Andrew Morton25.41%133.33%


Total37100.00%3100.00%





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;
}


Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o8665.15%450.00%


Linus Torvalds (pre-git)2821.21%225.00%


Hannes Frederic Sowa1712.88%112.50%


Al Viro10.76%112.50%


Total132100.00%8100.00%





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;
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)6784.81%562.50%


H. Peter Anvin810.13%112.50%


Matt Mackall22.53%112.50%


Greg Price22.53%112.50%


Total79100.00%8100.00%





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;
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)7679.17%758.33%


Matt Mackall1717.71%325.00%


Al Viro22.08%18.33%


Linus Torvalds11.04%18.33%


Total96100.00%12100.00%






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;
}


Contributors
PersonTokensPropCommitsCommitProp
Matt Mackall4688.46%125.00%


Linus Torvalds (pre-git)59.62%250.00%


Theodore Y. Ts'o11.92%125.00%


Total52100.00%4100.00%






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;
	}
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)18878.99%1055.56%


Al Viro156.30%15.56%


Theodore Y. Ts'o145.88%211.11%


H. Peter Anvin114.62%15.56%


Matt Mackall104.20%422.22%


Total238100.00%18100.00%






static int random_fasync(int fd, struct file *filp, int on)
{
	return fasync_helper(fd, filp, on, &fasync);
}


Contributors
PersonTokensPropCommitsCommitProp
Jeff Dike30100.00%1100.00%


Total30100.00%1100.00%




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);
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)10675.18%654.55%


Mathieu Desnoyers2517.73%19.09%


Linus Torvalds64.26%19.09%


Joe Perches32.13%218.18%


Al Viro10.71%19.09%


Total141100.00%11100.00%



/*
 * 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);
}


Contributors
PersonTokensPropCommitsCommitProp
H. Peter Anvin7697.44%150.00%


Joe Perches22.56%150.00%


Total78100.00%2100.00%




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;
};

/*
 * 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;
	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 (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
		extract_crng((u8 *)batch->entropy_u64);
		batch->position = 0;
	}
	ret = batch->entropy_u64[batch->position++];
	put_cpu_var(batched_entropy_u64);
	return ret;
}

Contributors
PersonTokensPropCommitsCommitProp
Jason A. Donenfeld9370.99%228.57%


H. Peter Anvin1511.45%114.29%


Linus Torvalds96.87%114.29%


Arjan van de Ven86.11%114.29%


David S. Miller53.82%114.29%


Al Viro10.76%114.29%


Total131100.00%7100.00%




EXPORT_SYMBOL(get_random_u64);

static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32);



u32 get_random_u32(void)
{
	u32 ret;
	struct batched_entropy *batch;

	if (arch_get_random_int(&ret))
		return ret;

	batch = &get_cpu_var(batched_entropy_u32);
	if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
		extract_crng((u8 *)batch->entropy_u32);
		batch->position = 0;
	}
	ret = batch->entropy_u32[batch->position++];
	put_cpu_var(batched_entropy_u32);
	return ret;
}

Contributors
PersonTokensPropCommitsCommitProp
Jason A. Donenfeld5259.09%266.67%


Daniel Cashman3640.91%133.33%


Total88100.00%3100.00%




EXPORT_SYMBOL(get_random_u32);

/**
 * 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);
}


Contributors
PersonTokensPropCommitsCommitProp
Jason Cooper79100.00%1100.00%


Total79100.00%1100.00%



/* 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);
}

Contributors
PersonTokensPropCommitsCommitProp
Torsten Duwe5676.71%133.33%


Theodore Y. Ts'o1723.29%266.67%


Total73100.00%3100.00%




EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);

Overall Contributors
PersonTokensPropCommitsCommitProp
Theodore Y. Ts'o352244.92%4220.90%


Linus Torvalds (pre-git)139617.80%2311.44%


Matt Mackall78710.04%4019.90%


H. Peter Anvin4886.22%83.98%


Herbert Xu2703.44%10.50%


Jason A. Donenfeld1922.45%21.00%


Andrew Morton1471.87%62.99%


Linus Torvalds1231.57%104.98%


Dave Jones1051.34%21.00%


Jarod Wilson881.12%21.00%


Jason Cooper801.02%10.50%


Greg Price740.94%104.98%


Hannes Frederic Sowa690.88%21.00%


Torsten Duwe650.83%10.50%


Jeff Dike640.82%10.50%


Al Viro480.61%31.49%


Daniel Cashman400.51%10.50%


Neil Horman340.43%10.50%


Mathieu Desnoyers250.32%10.50%


Jiri Kosina210.27%21.00%


Ingo Molnar180.23%21.00%


Yinghai Lu150.19%21.00%


Art Haas140.18%10.50%


Stephan Mueller110.14%21.00%


Arjan van de Ven100.13%21.00%


David Howells100.13%10.50%


Arnd Bergmann100.13%10.50%


George Spelvin80.10%10.50%


Tejun Heo80.10%10.50%


Andy Shevchenko70.09%21.00%


Serge E. Hallyn70.09%10.50%


Joe Perches70.09%31.49%


Bálint Márton70.09%21.00%


Michael Ellerman70.09%10.50%


Eric Dumazet60.08%10.50%


Fabio Estevam60.08%10.50%


David S. Miller60.08%10.50%


Olof Johansson60.08%10.50%


Arnaldo Carvalho de Melo50.06%21.00%


Christoph Hellwig50.06%10.50%


Brian Gerst50.06%10.50%


Dmitry Torokhov50.06%10.50%


Anton Blanchard40.05%10.50%


Daniel Borkmann30.04%10.50%


Andrea Righi30.04%10.50%


Christoph Lameter20.03%10.50%


Emese Revfy20.03%10.50%


Tony Luck20.03%21.00%


Stephen Hemminger10.01%10.50%


Lucas De Marchi10.01%10.50%


Eric W. Biedermann10.01%10.50%


Richard Kennedy10.01%10.50%


Total7841100.00%201100.00%


Directory: drivers/char



Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.
Created with cregit.