Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1629 insertions, 0 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
new file mode 100644
index 000000000000..ad9b52c2ae3c
--- /dev/null
+++ b/drivers/char/random.c
@@ -0,0 +1,1629 @@
+/*
+ * random.c -- A strong random number generator
+ *
+ * Version 1.89, last modified 19-Sep-99
+ *
+ * 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_input_randomness(unsigned int type, unsigned int code,
+ *                                unsigned int value);
+ *      void add_interrupt_randomness(int irq);
+ *
+ * add_input_randomness() uses the input layer interrupt timing, as well as
+ * the event type information from the hardware.
+ *
+ * add_interrupt_randomness() uses the inter-interrupt timing as random
+ * inputs to the entropy pool.  Note that not all interrupts are good
+ * sources of randomness!  For example, the timer interrupts is not a
+ * good choice, because the periodicity of the interrupts is too
+ * regular, and hence predictable to an attacker.  Disk interrupts are
+ * a better measure, since the timing of the disk interrupts are more
+ * unpredictable.
+ *
+ * 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/config.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/spinlock.h>
+#include <linux/percpu.h>
+#include <linux/cryptohash.h>
+
+#include <asm/processor.h>
+#include <asm/uaccess.h>
+#include <asm/irq.h>
+#include <asm/io.h>
+
+/*
+ * Configuration information
+ */
+#define INPUT_POOL_WORDS 128
+#define OUTPUT_POOL_WORDS 32
+#define SEC_XFER_SIZE 512
+
+/*
+ * 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_thresh = 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_thresh = 128;
+
+/*
+ * When the input pool goes over trickle_thresh, start dropping most
+ * samples to avoid wasting CPU time and reduce lock contention.
+ */
+
+static int trickle_thresh = INPUT_POOL_WORDS * 28;
+
+static DEFINE_PER_CPU(int, trickle_count) = 0;
+
+/*
+ * A pool of size .poolwords is stirred with a primitive polynomial
+ * of degree .poolwords over GF(2).  The taps for various sizes are
+ * defined below.  They are chosen to be evenly spaced (minimum RMS
+ * distance from evenly spaced; the numbers in the comments are a
+ * scaled squared error sum) except for the last tap, which is 1 to
+ * get the twisting happening as fast as possible.
+ */
+static struct poolinfo {
+        int poolwords;
+        int tap1, tap2, tap3, tap4, tap5;
+} poolinfo_table[] = {
+        /* x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 -- 105 */
+        { 128,  103,    76,     51,     25,     1 },
+        /* x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 -- 15 */
+        { 32,   26,     20,     14,     7,      1 },
+#if 0
+        /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1  -- 115 */
+        { 2048, 1638,   1231,   819,    411,    1 },
+
+        /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */
+        { 1024, 817,    615,    412,    204,    1 },
+
+        /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */
+        { 1024, 819,    616,    410,    207,    2 },
+
+        /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */
+        { 512,  411,    308,    208,    104,    1 },
+
+        /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */
+        { 512,  409,    307,    206,    102,    2 },
+        /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */
+        { 512,  409,    309,    205,    103,    2 },
+
+        /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */
+        { 256,  205,    155,    101,    52,     1 },
+
+        /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */
+        { 128,  103,    78,     51,     27,     2 },
+
+        /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */
+        { 64,   52,     39,     26,     14,     1 },
+#endif
+};
+
+#define POOLBITS        poolwords*32
+#define POOLBYTES       poolwords*4
+
+/*
+ * For the purposes of better mixing, we use the CRC-32 polynomial as
+ * well to make a twisted Generalized Feedback Shift Reigster
+ *
+ * (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 Mdeling and Computer Simulation 4:254-266)
+ *
+ * Thanks to Colin Plumb for suggesting this.
+ *
+ * We have not analyzed the resultant polynomial to prove it primitive;
+ * in fact it almost certainly isn't.  Nonetheless, the irreducible factors
+ * of a random large-degree polynomial over GF(2) are more than large enough
+ * that periodicity is not a concern.
+ *
+ * The input hash is much less sensitive than the output hash.  All
+ * that we want of it 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).
+ *
+ * The chosen system lets the state of the pool be (essentially) the input
+ * modulo the generator polymnomial.  Now, for random primitive polynomials,
+ * this is a universal class of hash functions, meaning that the chance
+ * of a collision is limited by the attacker's knowledge of the generator
+ * polynomail, so if it is chosen at random, an attacker can never force
+ * a collision.  Here, we use a fixed polynomial, but we *can* assume that
+ * ###--> it is unknown to the processes generating the input entropy. <-###
+ * Because of this important property, this is a good, collision-resistant
+ * hash; hash collisions will occur no more often than chance.
+ */
+
+/*
+ * Static global variables
+ */
+static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
+static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
+
+#if 0
+static int debug = 0;
+module_param(debug, bool, 0644);
+#define DEBUG_ENT(fmt, arg...) do { if (debug) \
+        printk(KERN_DEBUG "random %04d %04d %04d: " \
+        fmt,\
+        input_pool.entropy_count,\
+        blocking_pool.entropy_count,\
+        nonblocking_pool.entropy_count,\
+        ## arg); } while (0)
+#else
+#define DEBUG_ENT(fmt, arg...) do {} while (0)
+#endif
+
+/**********************************************************************
+ *
+ * OS independent entropy store.   Here are the functions which handle
+ * storing entropy in an entropy pool.
+ *
+ **********************************************************************/
+
+struct entropy_store;
+struct entropy_store {
+        /* mostly-read data: */
+        struct poolinfo *poolinfo;
+        __u32 *pool;
+        const char *name;
+        int limit;
+        struct entropy_store *pull;
+
+        /* read-write data: */
+        spinlock_t lock ____cacheline_aligned_in_smp;
+        unsigned add_ptr;
+        int entropy_count;
+        int input_rotate;
+};
+
+static __u32 input_pool_data[INPUT_POOL_WORDS];
+static __u32 blocking_pool_data[OUTPUT_POOL_WORDS];
+static __u32 nonblocking_pool_data[OUTPUT_POOL_WORDS];
+
+static struct entropy_store input_pool = {
+        .poolinfo = &poolinfo_table[0],
+        .name = "input",
+        .limit = 1,
+        .lock = SPIN_LOCK_UNLOCKED,
+        .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,
+        .pool = blocking_pool_data
+};
+
+static struct entropy_store nonblocking_pool = {
+        .poolinfo = &poolinfo_table[1],
+        .name = "nonblocking",
+        .pull = &input_pool,
+        .lock = SPIN_LOCK_UNLOCKED,
+        .pool = nonblocking_pool_data
+};
+
+/*
+ * This function adds a byte into the entropy "pool".  It does not
+ * update the entropy estimate.  The caller should call
+ * credit_entropy_store 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 __add_entropy_words(struct entropy_store *r, const __u32 *in,
+                                int nwords, __u32 out[16])
+{
+        static __u32 const twist_table[8] = {
+                0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
+                0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
+        unsigned long i, add_ptr, tap1, tap2, tap3, tap4, tap5;
+        int new_rotate, input_rotate;
+        int wordmask = r->poolinfo->poolwords - 1;
+        __u32 w, next_w;
+        unsigned long flags;
+
+        /* Taps are constant, so we can load them without holding r->lock.  */
+        tap1 = r->poolinfo->tap1;
+        tap2 = r->poolinfo->tap2;
+        tap3 = r->poolinfo->tap3;
+        tap4 = r->poolinfo->tap4;
+        tap5 = r->poolinfo->tap5;
+        next_w = *in++;
+
+        spin_lock_irqsave(&r->lock, flags);
+        prefetch_range(r->pool, wordmask);
+        input_rotate = r->input_rotate;
+        add_ptr = r->add_ptr;
+
+        while (nwords--) {
+                w = rol32(next_w, input_rotate);
+                if (nwords > 0)
+                        next_w = *in++;
+                i = add_ptr = (add_ptr - 1) & wordmask;
+                /*
+                 * 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.
+                 */
+                new_rotate = input_rotate + 14;
+                if (i)
+                        new_rotate = input_rotate + 7;
+                input_rotate = new_rotate & 31;
+
+                /* XOR in the various taps */
+                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];
+                w ^= r->pool[i];
+                r->pool[i] = (w >> 3) ^ twist_table[w & 7];
+        }
+
+        r->input_rotate = input_rotate;
+        r->add_ptr = add_ptr;
+
+        if (out) {
+                for (i = 0; i < 16; i++) {
+                        out[i] = r->pool[add_ptr];
+                        add_ptr = (add_ptr - 1) & wordmask;
+                }
+        }
+
+        spin_unlock_irqrestore(&r->lock, flags);
+}
+
+static inline void add_entropy_words(struct entropy_store *r, const __u32 *in,
+                                     int nwords)
+{
+        __add_entropy_words(r, in, nwords, NULL);
+}
+
+/*
+ * Credit (or debit) the entropy store with n bits of entropy
+ */
+static void credit_entropy_store(struct entropy_store *r, int nbits)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&r->lock, flags);
+
+        if (r->entropy_count + nbits < 0) {
+                DEBUG_ENT("negative entropy/overflow (%d+%d)\n",
+                          r->entropy_count, nbits);
+                r->entropy_count = 0;
+        } else if (r->entropy_count + nbits > r->poolinfo->POOLBITS) {
+                r->entropy_count = r->poolinfo->POOLBITS;
+        } else {
+                r->entropy_count += nbits;
+                if (nbits)
+                        DEBUG_ENT("added %d entropy credits to %s\n",
+                                  nbits, r->name);
+        }
+
+        spin_unlock_irqrestore(&r->lock, flags);
+}
+
+/*********************************************************************
+ *
+ * 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;
+};
+
+static struct timer_rand_state input_timer_state;
+static struct timer_rand_state *irq_timer_state[NR_IRQS];
+
+/*
+ * 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 {
+                cycles_t cycles;
+                long jiffies;
+                unsigned num;
+        } sample;
+        long delta, delta2, delta3;
+
+        preempt_disable();
+        /* if over the trickle threshold, use only 1 in 4096 samples */
+        if (input_pool.entropy_count > trickle_thresh &&
+            (__get_cpu_var(trickle_count)++ & 0xfff))
+                goto out;
+
+        sample.jiffies = jiffies;
+        sample.cycles = get_cycles();
+        sample.num = num;
+        add_entropy_words(&input_pool, (u32 *)&sample, sizeof(sample)/4);
+
+        /*
+         * 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_store(&input_pool,
+                                     min_t(int, fls(delta>>1), 11));
+        }
+
+        if(input_pool.entropy_count >= random_read_wakeup_thresh)
+                wake_up_interruptible(&random_read_wait);
+
+out:
+        preempt_enable();
+}
+
+extern 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;
+
+        DEBUG_ENT("input event\n");
+        last_value = value;
+        add_timer_randomness(&input_timer_state,
+                             (type << 4) ^ code ^ (code >> 4) ^ value);
+}
+
+void add_interrupt_randomness(int irq)
+{
+        if (irq >= NR_IRQS || irq_timer_state[irq] == 0)
+                return;
+
+        DEBUG_ENT("irq event %d\n", irq);
+        add_timer_randomness(irq_timer_state[irq], 0x100 + irq);
+}
+
+void add_disk_randomness(struct gendisk *disk)
+{
+        if (!disk || !disk->random)
+                return;
+        /* first major is 1, so we get >= 0x200 here */
+        DEBUG_ENT("disk event %d:%d\n", disk->major, disk->first_minor);
+
+        add_timer_randomness(disk->random,
+                             0x100 + MKDEV(disk->major, disk->first_minor));
+}
+
+EXPORT_SYMBOL(add_disk_randomness);
+
+#define EXTRACT_SIZE 10
+
+/*********************************************************************
+ *
+ * Entropy extraction routines
+ *
+ *********************************************************************/
+
+static ssize_t extract_entropy(struct entropy_store *r, void * buf,
+                               size_t nbytes, int min, int rsvd);
+
+/*
+ * This utility inline function is responsible for transfering 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)
+{
+        __u32 tmp[OUTPUT_POOL_WORDS];
+
+        if (r->pull && r->entropy_count < nbytes * 8 &&
+            r->entropy_count < r->poolinfo->POOLBITS) {
+                int bytes = max_t(int, random_read_wakeup_thresh / 8,
+                                min_t(int, nbytes, sizeof(tmp)));
+                int rsvd = r->limit ? 0 : random_read_wakeup_thresh/4;
+
+                DEBUG_ENT("going to reseed %s with %d bits "
+                          "(%d of %d requested)\n",
+                          r->name, bytes * 8, nbytes * 8, r->entropy_count);
+
+                bytes=extract_entropy(r->pull, tmp, bytes,
+                                      random_read_wakeup_thresh / 8, rsvd);
+                add_entropy_words(r, tmp, (bytes + 3) / 4);
+                credit_entropy_store(r, bytes*8);
+        }
+}
+
+/*
+ * These functions 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.
+ *
+ * Note: extract_entropy() assumes that .poolwords is a multiple of 16 words.
+ */
+
+static size_t account(struct entropy_store *r, size_t nbytes, int min,
+                      int reserved)
+{
+        unsigned long flags;
+
+        BUG_ON(r->entropy_count > r->poolinfo->POOLBITS);
+
+        /* Hold lock while accounting */
+        spin_lock_irqsave(&r->lock, flags);
+
+        DEBUG_ENT("trying to extract %d bits from %s\n",
+                  nbytes * 8, r->name);
+
+        /* Can we pull enough? */
+        if (r->entropy_count / 8 < min + reserved) {
+                nbytes = 0;
+        } else {
+                /* If limited, never pull more than available */
+                if (r->limit && nbytes + reserved >= r->entropy_count / 8)
+                        nbytes = r->entropy_count/8 - reserved;
+
+                if(r->entropy_count / 8 >= nbytes + reserved)
+                        r->entropy_count -= nbytes*8;
+                else
+                        r->entropy_count = reserved;
+
+                if (r->entropy_count < random_write_wakeup_thresh)
+                        wake_up_interruptible(&random_write_wait);
+        }
+
+        DEBUG_ENT("debiting %d entropy credits from %s%s\n",
+                  nbytes * 8, r->name, r->limit ? "" : " (unlimited)");
+
+        spin_unlock_irqrestore(&r->lock, flags);
+
+        return nbytes;
+}
+
+static void extract_buf(struct entropy_store *r, __u8 *out)
+{
+        int i, x;
+        __u32 data[16], buf[5 + SHA_WORKSPACE_WORDS];
+
+        sha_init(buf);
+        /*
+         * As we hash the pool, we mix intermediate values of
+         * the hash back into the pool.  This eliminates
+         * 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.
+         */
+        for (i = 0, x = 0; i < r->poolinfo->poolwords; i += 16, x+=2) {
+                sha_transform(buf, (__u8 *)r->pool+i, buf + 5);
+                add_entropy_words(r, &buf[x % 5], 1);
+        }
+
+        /*
+         * To avoid duplicates, we atomically extract a
+         * portion of the pool while mixing, and hash one
+         * final time.
+         */
+        __add_entropy_words(r, &buf[x % 5], 1, data);
+        sha_transform(buf, (__u8 *)data, buf + 5);
+
+        /*
+         * In case the hash function has some recognizable
+         * output pattern, we fold it in half.
+         */
+
+        buf[0] ^= buf[3];
+        buf[1] ^= buf[4];
+        buf[0] ^= rol32(buf[3], 16);
+        memcpy(out, buf, EXTRACT_SIZE);
+        memset(buf, 0, sizeof(buf));
+}
+
+static ssize_t extract_entropy(struct entropy_store *r, void * buf,
+                               size_t nbytes, int min, int reserved)
+{
+        ssize_t ret = 0, i;
+        __u8 tmp[EXTRACT_SIZE];
+
+        xfer_secondary_pool(r, nbytes);
+        nbytes = account(r, nbytes, min, reserved);
+
+        while (nbytes) {
+                extract_buf(r, tmp);
+                i = min_t(int, nbytes, EXTRACT_SIZE);
+                memcpy(buf, tmp, i);
+                nbytes -= i;
+                buf += i;
+                ret += i;
+        }
+
+        /* Wipe data just returned from memory */
+        memset(tmp, 0, sizeof(tmp));
+
+        return ret;
+}
+
+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];
+
+        xfer_secondary_pool(r, nbytes);
+        nbytes = account(r, nbytes, 0, 0);
+
+        while (nbytes) {
+                if (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 */
+        memset(tmp, 0, sizeof(tmp));
+
+        return ret;
+}
+
+/*
+ * This function is the exported kernel interface.  It returns some
+ * number of good random numbers, suitable for seeding TCP sequence
+ * numbers, etc.
+ */
+void get_random_bytes(void *buf, int nbytes)
+{
+        extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0);
+}
+
+EXPORT_SYMBOL(get_random_bytes);
+
+/*
+ * 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)
+{
+        struct timeval tv;
+        unsigned long flags;
+
+        spin_lock_irqsave(&r->lock, flags);
+        r->entropy_count = 0;
+        spin_unlock_irqrestore(&r->lock, flags);
+
+        do_gettimeofday(&tv);
+        add_entropy_words(r, (__u32 *)&tv, sizeof(tv)/4);
+        add_entropy_words(r, (__u32 *)&system_utsname,
+                          sizeof(system_utsname)/4);
+}
+
+static int __init rand_initialize(void)
+{
+        init_std_data(&input_pool);
+        init_std_data(&blocking_pool);
+        init_std_data(&nonblocking_pool);
+        return 0;
+}
+module_init(rand_initialize);
+
+void rand_initialize_irq(int irq)
+{
+        struct timer_rand_state *state;
+
+        if (irq >= NR_IRQS || irq_timer_state[irq])
+                return;
+
+        /*
+         * If kmalloc returns null, we just won't use that entropy
+         * source.
+         */
+        state = kmalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
+        if (state) {
+                memset(state, 0, sizeof(struct timer_rand_state));
+                irq_timer_state[irq] = state;
+        }
+}
+
+void rand_initialize_disk(struct gendisk *disk)
+{
+        struct timer_rand_state *state;
+
+        /*
+         * If kmalloc returns null, we just won't use that entropy
+         * source.
+         */
+        state = kmalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
+        if (state) {
+                memset(state, 0, sizeof(struct timer_rand_state));
+                disk->random = state;
+        }
+}
+
+static ssize_t
+random_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos)
+{
+        ssize_t n, retval = 0, count = 0;
+
+        if (nbytes == 0)
+                return 0;
+
+        while (nbytes > 0) {
+                n = nbytes;
+                if (n > SEC_XFER_SIZE)
+                        n = SEC_XFER_SIZE;
+
+                DEBUG_ENT("reading %d bits\n", n*8);
+
+                n = extract_entropy_user(&blocking_pool, buf, n);
+
+                DEBUG_ENT("read got %d bits (%d still needed)\n",
+                          n*8, (nbytes-n)*8);
+
+                if (n == 0) {
+                        if (file->f_flags & O_NONBLOCK) {
+                                retval = -EAGAIN;
+                                break;
+                        }
+
+                        DEBUG_ENT("sleeping?\n");
+
+                        wait_event_interruptible(random_read_wait,
+                                input_pool.entropy_count >=
+                                                 random_read_wakeup_thresh);
+
+                        DEBUG_ENT("awake\n");
+
+                        if (signal_pending(current)) {
+                                retval = -ERESTARTSYS;
+                                break;
+                        }
+
+                        continue;
+                }
+
+                if (n < 0) {
+                        retval = n;
+                        break;
+                }
+                count += n;
+                buf += n;
+                nbytes -= n;
+                break;          /* This break makes the device work */
+                                /* like a named pipe */
+        }
+
+        /*
+         * If we gave the user some bytes, update the access time.
+         */
+        if (count)
+                file_accessed(file);
+
+        return (count ? count : retval);
+}
+
+static ssize_t
+urandom_read(struct file * file, char __user * buf,
+                      size_t nbytes, loff_t *ppos)
+{
+        return extract_entropy_user(&nonblocking_pool, buf, nbytes);
+}
+
+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 (input_pool.entropy_count >= random_read_wakeup_thresh)
+                mask |= POLLIN | POLLRDNORM;
+        if (input_pool.entropy_count < random_write_wakeup_thresh)
+                mask |= POLLOUT | POLLWRNORM;
+        return mask;
+}
+
+static ssize_t
+random_write(struct file * file, const char __user * buffer,
+             size_t count, loff_t *ppos)
+{
+        int ret = 0;
+        size_t bytes;
+        __u32 buf[16];
+        const char __user *p = buffer;
+        size_t c = count;
+
+        while (c > 0) {
+                bytes = min(c, sizeof(buf));
+
+                bytes -= copy_from_user(&buf, p, bytes);
+                if (!bytes) {
+                        ret = -EFAULT;
+                        break;
+                }
+                c -= bytes;
+                p += bytes;
+
+                add_entropy_words(&input_pool, buf, (bytes + 3) / 4);
+        }
+        if (p == buffer) {
+                return (ssize_t)ret;
+        } else {
+                struct inode *inode = file->f_dentry->d_inode;
+                inode->i_mtime = current_fs_time(inode->i_sb);
+                mark_inode_dirty(inode);
+                return (ssize_t)(p - buffer);
+        }
+}
+
+static int
+random_ioctl(struct inode * inode, struct file * file,
+             unsigned int cmd, unsigned long arg)
+{
+        int size, ent_count;
+        int __user *p = (int __user *)arg;
+        int retval;
+
+        switch (cmd) {
+        case RNDGETENTCNT:
+                ent_count = input_pool.entropy_count;
+                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;
+                credit_entropy_store(&input_pool, ent_count);
+                /*
+                 * Wake up waiting processes if we have enough
+                 * entropy.
+                 */
+                if (input_pool.entropy_count >= random_read_wakeup_thresh)
+                        wake_up_interruptible(&random_read_wait);
+                return 0;
+        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 = random_write(file, (const char __user *) p,
+                                      size, &file->f_pos);
+                if (retval < 0)
+                        return retval;
+                credit_entropy_store(&input_pool, ent_count);
+                /*
+                 * Wake up waiting processes if we have enough
+                 * entropy.
+                 */
+                if (input_pool.entropy_count >= random_read_wakeup_thresh)
+                        wake_up_interruptible(&random_read_wait);
+                return 0;
+        case RNDZAPENTCNT:
+        case RNDCLEARPOOL:
+                /* Clear the entropy pool counters. */
+                if (!capable(CAP_SYS_ADMIN))
+                        return -EPERM;
+                init_std_data(&input_pool);
+                init_std_data(&blocking_pool);
+                init_std_data(&nonblocking_pool);
+                return 0;
+        default:
+                return -EINVAL;
+        }
+}
+
+struct file_operations random_fops = {
+        .read  = random_read,
+        .write = random_write,
+        .poll  = random_poll,
+        .ioctl = random_ioctl,
+};
+
+struct file_operations urandom_fops = {
+        .read  = urandom_read,
+        .write = random_write,
+        .ioctl = random_ioctl,
+};
+
+/***************************************************************
+ * Random UUID interface
+ *
+ * Used here for a Boot ID, but can be useful for other kernel
+ * drivers.
+ ***************************************************************/
+
+/*
+ * Generate random UUID
+ */
+void generate_random_uuid(unsigned char uuid_out[16])
+{
+        get_random_bytes(uuid_out, 16);
+        /* Set UUID version to 4 --- truely random generation */
+        uuid_out[6] = (uuid_out[6] & 0x0F) | 0x40;
+        /* Set the UUID variant to DCE */
+        uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80;
+}
+
+EXPORT_SYMBOL(generate_random_uuid);
+
+/********************************************************************
+ *
+ * Sysctl interface
+ *
+ ********************************************************************/
+
+#ifdef CONFIG_SYSCTL
+
+#include <linux/sysctl.h>
+
+static int min_read_thresh = 8, min_write_thresh;
+static int max_read_thresh = INPUT_POOL_WORDS * 32;
+static int max_write_thresh = INPUT_POOL_WORDS * 32;
+static char sysctl_bootid[16];
+
+/*
+ * These functions 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, it will be returned
+ * as an ASCII string in the standard UUID format.  If accesses via the
+ * sysctl system call, it is returned as 16 bytes of binary data.
+ */
+static int proc_do_uuid(ctl_table *table, int write, struct file *filp,
+                        void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+        ctl_table fake_table;
+        unsigned char buf[64], tmp_uuid[16], *uuid;
+
+        uuid = table->data;
+        if (!uuid) {
+                uuid = tmp_uuid;
+                uuid[8] = 0;
+        }
+        if (uuid[8] == 0)
+                generate_random_uuid(uuid);
+
+        sprintf(buf, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-"
+                "%02x%02x%02x%02x%02x%02x",
+                uuid[0],  uuid[1],  uuid[2],  uuid[3],
+                uuid[4],  uuid[5],  uuid[6],  uuid[7],
+                uuid[8],  uuid[9],  uuid[10], uuid[11],
+                uuid[12], uuid[13], uuid[14], uuid[15]);
+        fake_table.data = buf;
+        fake_table.maxlen = sizeof(buf);
+
+        return proc_dostring(&fake_table, write, filp, buffer, lenp, ppos);
+}
+
+static int uuid_strategy(ctl_table *table, int __user *name, int nlen,
+                         void __user *oldval, size_t __user *oldlenp,
+                         void __user *newval, size_t newlen, void **context)
+{
+        unsigned char tmp_uuid[16], *uuid;
+        unsigned int len;
+
+        if (!oldval || !oldlenp)
+                return 1;
+
+        uuid = table->data;
+        if (!uuid) {
+                uuid = tmp_uuid;
+                uuid[8] = 0;
+        }
+        if (uuid[8] == 0)
+                generate_random_uuid(uuid);
+
+        if (get_user(len, oldlenp))
+                return -EFAULT;
+        if (len) {
+                if (len > 16)
+                        len = 16;
+                if (copy_to_user(oldval, uuid, len) ||
+                    put_user(len, oldlenp))
+                        return -EFAULT;
+        }
+        return 1;
+}
+
+static int sysctl_poolsize = INPUT_POOL_WORDS * 32;
+ctl_table random_table[] = {
+        {
+                .ctl_name       = RANDOM_POOLSIZE,
+                .procname       = "poolsize",
+                .data           = &sysctl_poolsize,
+                .maxlen         = sizeof(int),
+                .mode           = 0444,
+                .proc_handler   = &proc_dointvec,
+        },
+        {
+                .ctl_name       = RANDOM_ENTROPY_COUNT,
+                .procname       = "entropy_avail",
+                .maxlen         = sizeof(int),
+                .mode           = 0444,
+                .proc_handler   = &proc_dointvec,
+                .data           = &input_pool.entropy_count,
+        },
+        {
+                .ctl_name       = RANDOM_READ_THRESH,
+                .procname       = "read_wakeup_threshold",
+                .data           = &random_read_wakeup_thresh,
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = &proc_dointvec_minmax,
+                .strategy       = &sysctl_intvec,
+                .extra1         = &min_read_thresh,
+                .extra2         = &max_read_thresh,
+        },
+        {
+                .ctl_name       = RANDOM_WRITE_THRESH,
+                .procname       = "write_wakeup_threshold",
+                .data           = &random_write_wakeup_thresh,
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = &proc_dointvec_minmax,
+                .strategy       = &sysctl_intvec,
+                .extra1         = &min_write_thresh,
+                .extra2         = &max_write_thresh,
+        },
+        {
+                .ctl_name       = RANDOM_BOOT_ID,
+                .procname       = "boot_id",
+                .data           = &sysctl_bootid,
+                .maxlen         = 16,
+                .mode           = 0444,
+                .proc_handler   = &proc_do_uuid,
+                .strategy       = &uuid_strategy,
+        },
+        {
+                .ctl_name       = RANDOM_UUID,
+                .procname       = "uuid",
+                .maxlen         = 16,
+                .mode           = 0444,
+                .proc_handler   = &proc_do_uuid,
+                .strategy       = &uuid_strategy,
+        },
+        { .ctl_name = 0 }
+};
+#endif  /* CONFIG_SYSCTL */
+
+/********************************************************************
+ *
+ * Random funtions for networking
+ *
+ ********************************************************************/
+
+/*
+ * TCP initial sequence number picking.  This uses the random number
+ * generator to pick an initial secret value.  This value is hashed
+ * along with the TCP endpoint information to provide a unique
+ * starting point for each pair of TCP endpoints.  This defeats
+ * attacks which rely on guessing the initial TCP sequence number.
+ * This algorithm was suggested by Steve Bellovin.
+ *
+ * Using a very strong hash was taking an appreciable amount of the total
+ * TCP connection establishment time, so this is a weaker hash,
+ * compensated for by changing the secret periodically.
+ */
+
+/* F, G and H are basic MD4 functions: selection, majority, parity */
+#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
+#define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
+#define H(x, y, z) ((x) ^ (y) ^ (z))
+
+/*
+ * The generic round function.  The application is so specific that
+ * we don't bother protecting all the arguments with parens, as is generally
+ * good macro practice, in favor of extra legibility.
+ * Rotation is separate from addition to prevent recomputation
+ */
+#define ROUND(f, a, b, c, d, x, s)      \
+        (a += f(b, c, d) + x, a = (a << s) | (a >> (32 - s)))
+#define K1 0
+#define K2 013240474631UL
+#define K3 015666365641UL
+
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+
+static __u32 twothirdsMD4Transform (__u32 const buf[4], __u32 const in[12])
+{
+        __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
+
+        /* Round 1 */
+        ROUND(F, a, b, c, d, in[ 0] + K1,  3);
+        ROUND(F, d, a, b, c, in[ 1] + K1,  7);
+        ROUND(F, c, d, a, b, in[ 2] + K1, 11);
+        ROUND(F, b, c, d, a, in[ 3] + K1, 19);
+        ROUND(F, a, b, c, d, in[ 4] + K1,  3);
+        ROUND(F, d, a, b, c, in[ 5] + K1,  7);
+        ROUND(F, c, d, a, b, in[ 6] + K1, 11);
+        ROUND(F, b, c, d, a, in[ 7] + K1, 19);
+        ROUND(F, a, b, c, d, in[ 8] + K1,  3);
+        ROUND(F, d, a, b, c, in[ 9] + K1,  7);
+        ROUND(F, c, d, a, b, in[10] + K1, 11);
+        ROUND(F, b, c, d, a, in[11] + K1, 19);
+
+        /* Round 2 */
+        ROUND(G, a, b, c, d, in[ 1] + K2,  3);
+        ROUND(G, d, a, b, c, in[ 3] + K2,  5);
+        ROUND(G, c, d, a, b, in[ 5] + K2,  9);
+        ROUND(G, b, c, d, a, in[ 7] + K2, 13);
+        ROUND(G, a, b, c, d, in[ 9] + K2,  3);
+        ROUND(G, d, a, b, c, in[11] + K2,  5);
+        ROUND(G, c, d, a, b, in[ 0] + K2,  9);
+        ROUND(G, b, c, d, a, in[ 2] + K2, 13);
+        ROUND(G, a, b, c, d, in[ 4] + K2,  3);
+        ROUND(G, d, a, b, c, in[ 6] + K2,  5);
+        ROUND(G, c, d, a, b, in[ 8] + K2,  9);
+        ROUND(G, b, c, d, a, in[10] + K2, 13);
+
+        /* Round 3 */
+        ROUND(H, a, b, c, d, in[ 3] + K3,  3);
+        ROUND(H, d, a, b, c, in[ 7] + K3,  9);
+        ROUND(H, c, d, a, b, in[11] + K3, 11);
+        ROUND(H, b, c, d, a, in[ 2] + K3, 15);
+        ROUND(H, a, b, c, d, in[ 6] + K3,  3);
+        ROUND(H, d, a, b, c, in[10] + K3,  9);
+        ROUND(H, c, d, a, b, in[ 1] + K3, 11);
+        ROUND(H, b, c, d, a, in[ 5] + K3, 15);
+        ROUND(H, a, b, c, d, in[ 9] + K3,  3);
+        ROUND(H, d, a, b, c, in[ 0] + K3,  9);
+        ROUND(H, c, d, a, b, in[ 4] + K3, 11);
+        ROUND(H, b, c, d, a, in[ 8] + K3, 15);
+
+        return buf[1] + b; /* "most hashed" word */
+        /* Alternative: return sum of all words? */
+}
+#endif
+
+#undef ROUND
+#undef F
+#undef G
+#undef H
+#undef K1
+#undef K2
+#undef K3
+
+/* This should not be decreased so low that ISNs wrap too fast. */
+#define REKEY_INTERVAL (300 * HZ)
+/*
+ * Bit layout of the tcp sequence numbers (before adding current time):
+ * bit 24-31: increased after every key exchange
+ * bit 0-23: hash(source,dest)
+ *
+ * The implementation is similar to the algorithm described
+ * in the Appendix of RFC 1185, except that
+ * - it uses a 1 MHz clock instead of a 250 kHz clock
+ * - it performs a rekey every 5 minutes, which is equivalent
+ *      to a (source,dest) tulple dependent forward jump of the
+ *      clock by 0..2^(HASH_BITS+1)
+ *
+ * Thus the average ISN wraparound time is 68 minutes instead of
+ * 4.55 hours.
+ *
+ * SMP cleanup and lock avoidance with poor man's RCU.
+ *                      Manfred Spraul <manfred@colorfullife.com>
+ *
+ */
+#define COUNT_BITS 8
+#define COUNT_MASK ((1 << COUNT_BITS) - 1)
+#define HASH_BITS 24
+#define HASH_MASK ((1 << HASH_BITS) - 1)
+
+static struct keydata {
+        __u32 count; /* already shifted to the final position */
+        __u32 secret[12];
+} ____cacheline_aligned ip_keydata[2];
+
+static unsigned int ip_cnt;
+
+static void rekey_seq_generator(void *private_);
+
+static DECLARE_WORK(rekey_work, rekey_seq_generator, NULL);
+
+/*
+ * Lock avoidance:
+ * The ISN generation runs lockless - it's just a hash over random data.
+ * State changes happen every 5 minutes when the random key is replaced.
+ * Synchronization is performed by having two copies of the hash function
+ * state and rekey_seq_generator always updates the inactive copy.
+ * The copy is then activated by updating ip_cnt.
+ * The implementation breaks down if someone blocks the thread
+ * that processes SYN requests for more than 5 minutes. Should never
+ * happen, and even if that happens only a not perfectly compliant
+ * ISN is generated, nothing fatal.
+ */
+static void rekey_seq_generator(void *private_)
+{
+        struct keydata *keyptr = &ip_keydata[1 ^ (ip_cnt & 1)];
+
+        get_random_bytes(keyptr->secret, sizeof(keyptr->secret));
+        keyptr->count = (ip_cnt & COUNT_MASK) << HASH_BITS;
+        smp_wmb();
+        ip_cnt++;
+        schedule_delayed_work(&rekey_work, REKEY_INTERVAL);
+}
+
+static inline struct keydata *get_keyptr(void)
+{
+        struct keydata *keyptr = &ip_keydata[ip_cnt & 1];
+
+        smp_rmb();
+
+        return keyptr;
+}
+
+static __init int seqgen_init(void)
+{
+        rekey_seq_generator(NULL);
+        return 0;
+}
+late_initcall(seqgen_init);
+
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+__u32 secure_tcpv6_sequence_number(__u32 *saddr, __u32 *daddr,
+                                   __u16 sport, __u16 dport)
+{
+        struct timeval tv;
+        __u32 seq;
+        __u32 hash[12];
+        struct keydata *keyptr = get_keyptr();
+
+        /* The procedure is the same as for IPv4, but addresses are longer.
+         * Thus we must use twothirdsMD4Transform.
+         */
+
+        memcpy(hash, saddr, 16);
+        hash[4]=(sport << 16) + dport;
+        memcpy(&hash[5],keyptr->secret,sizeof(__u32) * 7);
+
+        seq = twothirdsMD4Transform(daddr, hash) & HASH_MASK;
+        seq += keyptr->count;
+
+        do_gettimeofday(&tv);
+        seq += tv.tv_usec + tv.tv_sec * 1000000;
+
+        return seq;
+}
+EXPORT_SYMBOL(secure_tcpv6_sequence_number);
+#endif
+
+/*  The code below is shamelessly stolen from secure_tcp_sequence_number().
+ *  All blames to Andrey V. Savochkin <saw@msu.ru>.
+ */
+__u32 secure_ip_id(__u32 daddr)
+{
+        struct keydata *keyptr;
+        __u32 hash[4];
+
+        keyptr = get_keyptr();
+
+        /*
+         *  Pick a unique starting offset for each IP destination.
+         *  The dest ip address is placed in the starting vector,
+         *  which is then hashed with random data.
+         */
+        hash[0] = daddr;
+        hash[1] = keyptr->secret[9];
+        hash[2] = keyptr->secret[10];
+        hash[3] = keyptr->secret[11];
+
+        return half_md4_transform(hash, keyptr->secret);
+}
+
+#ifdef CONFIG_INET
+
+__u32 secure_tcp_sequence_number(__u32 saddr, __u32 daddr,
+                                 __u16 sport, __u16 dport)
+{
+        struct timeval tv;
+        __u32 seq;
+        __u32 hash[4];
+        struct keydata *keyptr = get_keyptr();
+
+        /*
+         *  Pick a unique starting offset for each TCP connection endpoints
+         *  (saddr, daddr, sport, dport).
+         *  Note that the words are placed into the starting vector, which is
+         *  then mixed with a partial MD4 over random data.
+         */
+        hash[0]=saddr;
+        hash[1]=daddr;
+        hash[2]=(sport << 16) + dport;
+        hash[3]=keyptr->secret[11];
+
+        seq = half_md4_transform(hash, keyptr->secret) & HASH_MASK;
+        seq += keyptr->count;
+        /*
+         *      As close as possible to RFC 793, which
+         *      suggests using a 250 kHz clock.
+         *      Further reading shows this assumes 2 Mb/s networks.
+         *      For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
+         *      That's funny, Linux has one built in!  Use it!
+         *      (Networks are faster now - should this be increased?)
+         */
+        do_gettimeofday(&tv);
+        seq += tv.tv_usec + tv.tv_sec * 1000000;
+#if 0
+        printk("init_seq(%lx, %lx, %d, %d) = %d\n",
+               saddr, daddr, sport, dport, seq);
+#endif
+        return seq;
+}
+
+EXPORT_SYMBOL(secure_tcp_sequence_number);
+
+
+
+/* Generate secure starting point for ephemeral TCP port search */
+u32 secure_tcp_port_ephemeral(__u32 saddr, __u32 daddr, __u16 dport)
+{
+        struct keydata *keyptr = get_keyptr();
+        u32 hash[4];
+
+        /*
+         *  Pick a unique starting offset for each ephemeral port search
+         *  (saddr, daddr, dport) and 48bits of random data.
+         */
+        hash[0] = saddr;
+        hash[1] = daddr;
+        hash[2] = dport ^ keyptr->secret[10];
+        hash[3] = keyptr->secret[11];
+
+        return half_md4_transform(hash, keyptr->secret);
+}
+
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+u32 secure_tcpv6_port_ephemeral(const __u32 *saddr, const __u32 *daddr, __u16 dport)
+{
+        struct keydata *keyptr = get_keyptr();
+        u32 hash[12];
+
+        memcpy(hash, saddr, 16);
+        hash[4] = dport;
+        memcpy(&hash[5],keyptr->secret,sizeof(__u32) * 7);
+
+        return twothirdsMD4Transform(daddr, hash);
+}
+EXPORT_SYMBOL(secure_tcpv6_port_ephemeral);
+#endif
+
+#endif /* CONFIG_INET */
+
+
+/*
+ * 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)
+{
+        /*
+         * Use IP's RNG. It suits our purpose perfectly: it re-keys itself
+         * every second, from the entropy pool (and thus creates a limited
+         * drain on it), and uses halfMD4Transform within the second. We
+         * also mix it with jiffies and the PID:
+         */
+        return secure_ip_id(current->pid + jiffies);
+}
+
+/*
+ * randomize_range() returns a start address such that
+ *
+ *    [...... <range> .....]
+ *  start                  end
+ *
+ * a <range> with size "len" starting at the return value is inside in the
+ * area defined by [start, end], but is otherwise randomized.
+ */
+unsigned long
+randomize_range(unsigned long start, unsigned long end, unsigned long len)
+{
+        unsigned long range = end - len - start;
+
+        if (end <= start + len)
+                return 0;
+        return PAGE_ALIGN(get_random_int() % range + start);
+}