cregit-Linux how code gets into the kernel

Release 4.10 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;

/*
 * The minimum number of seconds between urandom pool reseeding.  We
 * do this to limit the amount of entropy that can be drained from the
 * input pool even if there are heavy demands on /dev/urandom.
 */

static int random_min_urandom_seed = 60;

/*
 * 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 DECLARE_WAIT_QUEUE_HEAD(urandom_init_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 limit: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",
	.limit = 1,
	.lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
	.pool = input_pool_data
};


static struct entropy_store blocking_pool = {
	.poolinfo = &poolinfo_table[1],
	.name = "blocking",
	.limit = 1,
	.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
pre-gitpre-git13248.35%529.41%
andrew mortonandrew morton6925.27%15.88%
matt mackallmatt mackall4616.85%847.06%
linus torvaldslinus torvalds165.86%15.88%
theodore tsotheodore tso103.66%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 tsotheodore tso39100.00%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 tsotheodore tso3860.32%250.00%
matt mackallmatt 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 tsotheodore tso21896.46%375.00%
george spelvingeorge 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 xuherbert 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 tsotheodore tso17645.01%626.09%
h. peter anvinh. peter anvin11228.64%28.70%
matt mackallmatt mackall4712.02%313.04%
andrew mortonandrew morton143.58%28.70%
linus torvaldslinus torvalds143.58%28.70%
jeff dikejeff dike112.81%14.35%
pre-gitpre-git71.79%313.04%
greg pricegreg price61.53%28.70%
hannes frederic sowahannes 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 tsotheodore tso62100.00%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 tsotheodore tso13598.54%375.00%
hannes frederic sowahannes 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 tsotheodore tso140100.00%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 tsotheodore tso222100.00%3100.00%
Total222100.00%3100.00%


static inline void maybe_reseed_primary_crng(void) { if (crng_init > 2 && time_after(jiffies, primary_crng.init_time + CRNG_RESEED_INTERVAL)) crng_reseed(&primary_crng, &input_pool); }

Contributors

PersonTokensPropCommitsCommitProp
theodore tsotheodore tso35100.00%1100.00%
Total35100.00%1100.00%


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

Contributors

PersonTokensPropCommitsCommitProp
theodore tsotheodore tso17100.00%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 tsotheodore tso12298.39%466.67%
hannes frederic sowahannes frederic sowa10.81%116.67%
pre-gitpre-git10.81%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 tsotheodore tso54100.00%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 tsotheodore tso128100.00%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 tsotheodore tso59100.00%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 tsotheodore tso12082.76%240.00%
h. peter anvinh. peter anvin1611.03%120.00%
jeff dikejeff dike74.83%120.00%
matt mackallmatt 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 torvaldslinus torvalds4456.41%125.00%
theodore tsotheodore tso3443.59%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
pre-gitpre-git13061.32%640.00%
matt mackallmatt mackall5827.36%320.00%
theodore tsotheodore tso136.13%213.33%
ingo molnaringo molnar62.83%16.67%
linus torvaldslinus torvalds31.42%16.67%
anton blanchardanton blanchard10.47%16.67%
brian gerstbrian gerst10.47%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 mackallmatt mackall3756.92%114.29%
pre-gitpre-git1523.08%457.14%
theodore tsotheodore tso913.85%114.29%
brian gerstbrian 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 tsotheodore tso58100.00%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 tsotheodore tso69100.00%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 tsotheodore tso29882.78%960.00%
h. peter anvinh. peter anvin349.44%16.67%
pre-gitpre-git164.44%213.33%
yinghai luyinghai lu61.67%16.67%
matt mackallmatt mackall41.11%16.67%
christoph lameterchristoph 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 viroal viro1530.00%114.29%
pre-gitpre-git1224.00%342.86%
theodore tsotheodore tso1122.00%114.29%
tejun heotejun heo816.00%114.29%
matt mackallmatt 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; if (r->limit == 0 && random_min_urandom_seed) { unsigned long now = jiffies; if (time_before(now, r->last_pulled + random_min_urandom_seed * HZ)) return; r->last_pulled = now; } _xfer_secondary_pool(r, nbytes); }

Contributors

PersonTokensPropCommitsCommitProp
theodore tsotheodore tso7176.34%350.00%
matt mackallmatt mackall1718.28%233.33%
pre-gitpre-git55.38%116.67%
Total93100.00%6100.00%


static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes) { __u32 tmp[OUTPUT_POOL_WORDS]; /* For /dev/random's pool, always leave two wakeups' worth */ int rsvd_bytes = r->limit ? 0 : random_read_wakeup_bits / 4; 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, rsvd_bytes); mix_pool_bytes(r, tmp, bytes); credit_entropy_bits(r, bytes*8); }

Contributors

PersonTokensPropCommitsCommitProp
matt mackallmatt mackall5340.15%746.67%
theodore tsotheodore tso2821.21%213.33%
pre-gitpre-git2115.91%320.00%
linus torvaldslinus torvalds1511.36%16.67%
andrew mortonandrew morton86.06%16.67%
greg pricegreg price75.30%16.67%
Total132100.00%15100.00%

/* * 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 tsotheodore tso6096.77%133.33%
greg pricegreg price11.61%133.33%
pre-gitpre-git11.61%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; 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; /* If limited, never pull more than available */ if (r->limit) { int 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 tsotheodore tso6025.00%420.00%
hannes frederic sowahannes frederic sowa4518.75%15.00%
pre-gitpre-git3414.17%210.00%
h. peter anvinh. peter anvin2912.08%15.00%
greg pricegreg price2811.67%315.00%
matt mackallmatt mackall218.75%525.00%
jiri kosinajiri kosina145.83%15.00%
andrew mortonandrew morton83.33%210.00%
linus torvaldslinus torvalds10.42%15.00%
Total240100.00%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 mackallmatt mackall10340.55%1365.00%
theodore tsotheodore tso6927.17%315.00%
pre-gitpre-git4116.14%210.00%
h. peter anvinh. peter anvin3915.35%15.00%
daniel borkmanndaniel 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 tsotheodore tso7649.67%233.33%
matt mackallmatt mackall4026.14%233.33%
jarod wilsonjarod 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 tsotheodore tso8948.11%111.11%
jarod wilsonjarod wilson4725.41%222.22%
neil hormanneil horman2815.14%111.11%
pre-gitpre-git94.86%222.22%
matt mackallmatt mackall94.86%222.22%
h. peter anvinh. 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 mackallmatt mackall10659.22%225.00%
pre-gitpre-git4525.14%225.00%
theodore tsotheodore tso2413.41%225.00%
h. peter anvinh. peter anvin31.68%112.50%
daniel borkmanndaniel 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 tsotheodore tso11090.91%583.33%
pre-gitpre-git119.09%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 xuherbert xu10096.15%150.00%
theodore tsotheodore tso43.85%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 xuherbert 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 anvinh. peter anvin6167.03%112.50%
theodore tsotheodore tso2325.27%450.00%
pre-gitpre-git66.59%225.00%
tony lucktony 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 tsotheodore tso5446.15%426.67%
pre-gitpre-git3126.50%320.00%
h. peter anvinh. peter anvin1210.26%320.00%
serge hallynserge hallyn75.98%16.67%
matt mackallmatt mackall75.98%213.33%
eric dumazeteric dumazet43.42%16.67%
jarod wilsonjarod 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 tsotheodore tso8974.17%325.00%
pre-gitpre-git108.33%325.00%
marton balintmarton balint75.83%216.67%
matt mackallmatt mackall54.17%216.67%
andrew mortonandrew morton54.17%18.33%
michael ellermanmichael 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
pre-gitpre-git2859.57%350.00%
al viroal viro919.15%116.67%
theodore tsotheodore tso817.02%116.67%
eric dumazeteric 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
pre-gitpre-git4633.82%423.53%
greg pricegreg price2316.91%211.76%
andrew mortonandrew morton2316.91%15.88%
theodore tsotheodore tso1712.50%211.76%
matt mackallmatt mackall128.82%423.53%
jiri kosinajiri kosina75.15%15.88%
h. peter anvinh. peter anvin75.15%211.76%
al viroal 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 tsotheodore tso2670.27%133.33%
pre-gitpre-git924.32%133.33%
andrew mortonandrew 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 tsotheodore tso8665.15%450.00%
pre-gitpre-git2821.21%225.00%
hannes frederic sowahannes frederic sowa1712.88%112.50%
al viroal 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
pre-gitpre-git6784.81%562.50%
h. peter anvinh. peter anvin810.13%112.50%
greg pricegreg price22.53%112.50%
matt mackallmatt mackall22.53%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
pre-gitpre-git7679.17%758.33%
matt mackallmatt mackall1717.71%325.00%
al viroal viro22.08%18.33%
linus torvaldslinus 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 mackallmatt mackall4688.46%125.00%
pre-gitpre-git59.62%250.00%
theodore tsotheodore tso11.92%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
pre-gitpre-git18878.99%1055.56%
al viroal viro156.30%15.56%
theodore tsotheodore tso145.88%211.11%
h. peter anvinh. peter anvin114.62%15.56%
matt mackallmatt 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 dikejeff 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 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
pre-gitpre-git10675.18%654.55%
mathieu desnoyersmathieu desnoyers2517.73%19.09%
linus torvaldslinus torvalds64.26%19.09%
joe perchesjoe perches32.13%218.18%
al viroal 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 anvinh. peter anvin7697.44%150.00%
joe perchesjoe 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 */ static u32 random_int_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
int random_int_secret_init(void) { get_random_bytes(random_int_secret, sizeof(random_int_secret)); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
stephen hemmingerstephen hemminger1155.00%133.33%
david s. millerdavid s. miller630.00%133.33%
arnaldo carvalho de meloarnaldo carvalho de melo315.00%133.33%
Total20100.00%3100.00%

static DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash) __aligned(sizeof(unsigned long)); /* * Get a random word for internal kernel use only. Similar to urandom but * with the goal of minimal entropy pool depletion. As a result, the random * value is not cryptographically secure but for several uses the cost of * depleting entropy is too high */
unsigned int get_random_int(void) { __u32 *hash; unsigned int ret; if (arch_get_random_int(&ret)) return ret; hash = get_cpu_var(get_random_int_hash); hash[0] += current->pid + jiffies + random_get_entropy(); md5_transform(hash, random_int_secret); ret = hash[0]; put_cpu_var(get_random_int_hash); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
linus torvaldslinus torvalds2535.71%116.67%
h. peter anvinh. peter anvin1825.71%116.67%
arjan van de venarjan van de ven1521.43%116.67%
david s. millerdavid s. miller1014.29%116.67%
al viroal viro11.43%116.67%
theodore tsotheodore tso11.43%116.67%
Total70100.00%6100.00%

EXPORT_SYMBOL(get_random_int); /* * Same as get_random_int(), but returns unsigned long. */
unsigned long get_random_long(void) { __u32 *hash; unsigned long ret; if (arch_get_random_long(&ret)) return ret; hash = get_cpu_var(get_random_int_hash); hash[0] += current->pid + jiffies + random_get_entropy(); md5_transform(hash, random_int_secret); ret = *(unsigned long *)hash; put_cpu_var(get_random_int_hash); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
daniel cashmandaniel cashman73100.00%1100.00%
Total73100.00%1100.00%

EXPORT_SYMBOL(get_random_long); /** * 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 cooperjason 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 duwetorsten duwe5676.71%133.33%
theodore tsotheodore tso1723.29%266.67%
Total73100.00%3100.00%

EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);

Overall Contributors

PersonTokensPropCommitsCommitProp
theodore tsotheodore tso361045.82%4221.00%
pre-gitpre-git139617.72%2311.50%
matt mackallmatt mackall82110.42%4120.50%
h. peter anvinh. peter anvin4916.23%84.00%
herbert xuherbert xu2703.43%10.50%
andrew mortonandrew morton1521.93%63.00%
linus torvaldslinus torvalds1391.76%105.00%
dave jonesdave jones1051.33%21.00%
jarod wilsonjarod wilson881.12%21.00%
jason cooperjason cooper801.02%10.50%
daniel cashmandaniel cashman791.00%10.50%
greg pricegreg price791.00%105.00%
hannes frederic sowahannes frederic sowa690.88%21.00%
torsten duwetorsten duwe650.83%10.50%
jeff dikejeff dike640.81%10.50%
al viroal viro490.62%31.50%
neil hormanneil horman340.43%10.50%
mathieu desnoyersmathieu desnoyers250.32%10.50%
david s. millerdavid s. miller230.29%10.50%
jiri kosinajiri kosina210.27%21.00%
ingo molnaringo molnar180.23%21.00%
arjan van de venarjan van de ven170.22%21.00%
yinghai luyinghai lu150.19%21.00%
art haasart haas140.18%10.50%
stephen hemmingerstephen hemminger130.17%21.00%
eric biggerseric biggers110.14%10.50%
david howellsdavid howells100.13%10.50%
arnd bergmannarnd bergmann100.13%10.50%
andy shevchenkoandy shevchenko80.10%21.00%
george spelvingeorge spelvin80.10%10.50%
tejun heotejun heo80.10%10.50%
joe perchesjoe perches70.09%31.50%
marton balintmarton balint70.09%21.00%
michael ellermanmichael ellerman70.09%10.50%
serge hallynserge hallyn70.09%10.50%
arnaldo carvalho de meloarnaldo carvalho de melo70.09%21.00%
olof johanssonolof johansson60.08%10.50%
eric dumazeteric dumazet60.08%10.50%
stephan muellerstephan mueller50.06%10.50%
christoph hellwigchristoph hellwig50.06%10.50%
brian gerstbrian gerst50.06%10.50%
dmitry torokhovdmitry torokhov50.06%10.50%
anton blanchardanton blanchard40.05%10.50%
daniel borkmanndaniel borkmann30.04%10.50%
andrea righiandrea righi30.04%10.50%
emese revfyemese revfy20.03%10.50%
christoph lameterchristoph lameter20.03%10.50%
tony lucktony luck20.03%21.00%
richard kennedyrichard kennedy10.01%10.50%
eric w. biedermaneric w. biederman10.01%10.50%
lucas de marchilucas de marchi10.01%10.50%
Total7878100.00%200100.00%
Directory: drivers/char
Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.