Re: [PROPOSAL/PATCH 2] Fortuna PRNG in /dev/random

Jean-Luc Cooke
2004-10-01T13:07:14Z

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Chris Han pointed out that my #include of "random-fortuna.c" could be done
much cleaner if the drivers/char/Makefile had some ifeq-else-endif logic in
it. He also pointed our my #include of crypto/internal.h was not needed
anymore.

Here is an update. v2.1.5 1-Oct-2004

JLC

On Thu, Sep 30, 2004 at 09:36:49AM -0400, Jean-Luc Cooke wrote:
> In the random-fortuna.c file I have some "#if !defined CONFIG_CRYPTO_SHA256"
>
> As Jan-Benedict Glaw pointed out, I could just manually select the
> algorithms, which is what I did.
>
> Updated patch, only changes are to crypto/Kconfig.
>
> Cheers,
>
> JLC
>
> On Thu, Sep 30, 2004 at 11:03:52AM +0200, Felipe Alfaro Solana wrote:
> > On Sep 30, 2004, at 06:23, Jean-Luc Cooke wrote:
> >
> > ><fortuna-2.6.8.1.patch>
> >
> > You said AES and SHA-256 _must_ be built-in, but I can't see any code
> > on your patch that enforces selection of those config options. Thus,
> > it's possible to compile the kernel when CONFIG_CRYPTO_SHA256=n and
> > CONFIG_CRYPTO_AES=n although, of course, it will fail.

[-- Attachment #2: fortuna-2.6.8.1.patch --]
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--- linux-2.6.8.1/crypto/Kconfig 2004-08-14 06:56:22.000000000 -0400
+++ linux-2.6.8.1-rand2/crypto/Kconfig 2004-09-30 09:33:39.775410632 -0400
@@ -9,6 +9,17 @@
help
This option provides the core Cryptographic API.

+config CRYPTO_RANDOM_FORTUNA
+ bool "The Fortuna RNG"
+ select CRYPTO_SHA256
+ select CRYPTO_AES
+ help
+ Replaces the legacy Linux RNG with one using the crypto API
+ and Fortuna by Ferguson and Schneier. Entropy estimation, and
+ a throttled /dev/random remain. Improvements include faster
+ /dev/urandom output and event input mixing.
+ Note: Requires AES and SHA256 to be built-in.
+
config CRYPTO_HMAC
bool "HMAC support"
depends on CRYPTO
diff -X exclude -Nur linux-2.6.8.1/include/linux/sysctl.h linux-2.6.8.1-rand2/include/linux/sysctl.h
--- linux-2.6.8.1/include/linux/sysctl.h 2004-08-14 06:55:33.000000000 -0400
+++ linux-2.6.8.1-rand2/include/linux/sysctl.h 2004-09-29 10:45:20.592695040 -0400
@@ -198,7 +198,9 @@
RANDOM_READ_THRESH=3,
RANDOM_WRITE_THRESH=4,
RANDOM_BOOT_ID=5,
- RANDOM_UUID=6
+ RANDOM_UUID=6,
+ RANDOM_DIGEST_ALGO=7,
+ RANDOM_CIPHER_ALGO=8
};

/* /proc/sys/kernel/pty */
diff -X exclude -Nur linux-2.6.8.1/drivers/char/Makefile linux-2.6.8.1-rand2/drivers/char/Makefile
--- linux-2.6.8.1/drivers/char/Makefile 2004-08-14 06:56:22.000000000 -0400
+++ linux-2.6.8.1-rand2/drivers/char/Makefile 2004-10-01 08:50:06.419933088 -0400
@@ -7,7 +7,13 @@
#
FONTMAPFILE = cp437.uni

-obj-y += mem.o random.o tty_io.o n_tty.o tty_ioctl.o pty.o misc.o
+obj-y += mem.o
+ifeq ($(CONFIG_CRYPTO_RANDOM_FORTUNA),y)
+ obj-y += random-fortuna.o
+ else
+ obj-y += random.o
+endif
+obj-y += tty_io.o n_tty.o tty_ioctl.o pty.o misc.o

obj-$(CONFIG_VT) += vt_ioctl.o vc_screen.o consolemap.o \
consolemap_deftbl.o selection.o keyboard.o
diff -X exclude -Nur linux-2.6.8.1/drivers/char/random-fortuna.c linux-2.6.8.1-rand2/drivers/char/random-fortuna.c
--- linux-2.6.8.1/drivers/char/random-fortuna.c 1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6.8.1-rand2/drivers/char/random-fortuna.c 2004-10-01 08:56:36.030703248 -0400
@@ -0,0 +1,2094 @@
+/*
+ * random-fortuna.c -- A cryptographically strong random number generator
+ * using Fortuna.
+ *
+ * Version 2.1.5, last modified 1-Oct-2004
+ * Change log:
+ * v2.1.5:
+ * - random-fortuna.c is no longer #include'd from random.c, the
+ * drivers/char/Makefile takes care of this now thanks to Chris Han
+ * v2.1.4:
+ * - Fixed flaw where some situations, /dev/random would not block.
+ * v2.1.3:
+ * - Added a seperate round-robin index for use inputs. Avoids a
+ * super-cleaver user from forcing all system (unknown) random
+ * events from being fed into, say, pool-31.
+ * - Added a "can only extract RANDOM_MAX_EXTRACT_SIZE bytes at a time"
+ * to extract_entropy()
+ * v2.1.2:
+ * - Ts'o's (I love writting that!) recomendation to force reseeds
+ * to be at least 0.1 ms apart.
+ * v2.1.1:
+ * - Re-worked to keep the blocking /dev/random. Yes I finally gave
+ * in to what everyone's been telling me.
+ * - Entropy accounting is *only* done on events going into pool-0
+ * since it's used for every reseed. Those who expect /dev/random
+ * to only output data when the system is confident it has
+ * info-theoretic entropy to justify this output, this is the only
+ * sensible method to count entropy.
+ * v2.0:
+ * - Inital version
+ *
+ * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All
+ * rights reserved.
+ * Copyright Jean-Luc Cooke, 2004. 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.
+ */
+
+/*
+ * Taken from random.c, updated by Jean-Luc Cooke <jlcooke@certainkey.com>
+ * (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.
+ * 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.
+ *
+ * Even if it is possible to analyze Fortuna in some clever way, as
+ * long as the amount of data returned from the generator is less than
+ * the inherent entropy we've estimated 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 Fortuna, 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_keyboard_randomness(unsigned char scancode);
+ * void add_mouse_randomness(__u32 mouse_data);
+ * void add_interrupt_randomness(int irq);
+ *
+ * add_keyboard_randomness() uses the inter-keypress timing, as well as the
+ * scancode as random inputs into the "entropy pool".
+ *
+ * add_mouse_randomness() uses the mouse interrupt timing, as well as
+ * the reported position of the mouse 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=8 bs=256
+ *
+ * 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
+ * # Fortuna resists using all of its pool matirial, so we need to
+ * # draw 8 seperate times (count=8) to ensure we get the entropy
+ * # from pool[0,1,2,3]'s entropy. count=2048 pool[0 .. 10], etc.
+ * 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=8 bs=256
+ *
+ * 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 (jlcooke) responsibility, and
+ * should not be attributed to the Phil, Colin, or any of authors of PGP
+ * or the legacy random.c (Ted Ts'o).
+ *
+ * Further background information on this topic may be obtained from
+ * RFC 1750, "Randomness Recommendations for Security", by Donald
+ * Eastlake, Steve Crocker, and Jeff Schiller. And Chapter 10 of
+ * Practical Cryptography by Ferguson and Schneier.
+ */
+
+#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/workqueue.h>
+#include <linux/genhd.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/percpu.h>
+#include <linux/crypto.h>
+
+#include <asm/scatterlist.h>
+#include <asm/processor.h>
+#include <asm/uaccess.h>
+#include <asm/irq.h>
+#include <asm/io.h>
+
+
+/*
+ * Configuration information
+ */
+#define BATCH_ENTROPY_SIZE 256
+/* milli-seconds between random_reseeds for non-blocking reads */
+#define RANDOM_RESEED_INTERVAL 100
+/*
+ * Number of bytes you can extract at a time, 1MB is recomended in
+ * Practical Cryptography rev-0
+ */
+#define RANDOM_MAX_EXTRACT_SIZE (1<<20)
+#define USE_SHA256
+#define USE_AES
+
+/*
+ * Compile-time checking for our desired message digest
+ */
+#if defined USE_SHA256
+ #if !CONFIG_CRYPTO_SHA256
+ #error SHA256 not a built-in module, Fortuna configured to use it.
+ #endif
+ #define RANDOM_DEFAULT_DIGEST_ALGO "sha256"
+#elif defined USE_WHIRLPOOL
+ #if !CONFIG_CRYPTO_WHIRLPOOL
+ #error WHIRLPOOL not a built-in module, Fortuna configured to use it.
+ #endif
+ #define RANDOM_DEFAULT_DIGEST_ALGO "whirlpool"
+#else
+ #error Desired message digest algorithm not found
+#endif
+
+/*
+ * Compile-time checking for our desired block cipher
+ */
+#if defined USE_AES
+ #if (!CONFIG_CRYPTO_AES && !CONFIG_CRYPTO_AES_586)
+ #error AES not a built-in module, Fortuna configured to use it.
+ #endif
+ #define RANDOM_DEFAULT_CIPHER_ALGO "aes"
+#elif defined USE_TWOFISH
+ #if (!CONFIG_CRYPTO_TWOFISH && !CONFIG_CRYPTO_TWOFISH_586)
+ #error TWOFISH not a built-in module, Fortuna configured to use it.
+ #endif
+ #define RANDOM_DEFAULT_CIPHER_ALGO "twofish"
+#else
+ #error Desired block cipher algorithm not found
+#endif /* USE_AES */
+
+#define DEFAULT_POOL_NUMBER 5 /* 2^{5} = 32 pools */
+#define DEFAULT_POOL_SIZE ( (1<<DEFAULT_POOL_NUMBER) * 256)
+/* largest block of random data to extract at a time when in blocking-mode */
+#define TMP_BUF_SIZE 512
+/* SHA512/WHIRLPOOL have 64bytes == 512 bits */
+#define RANDOM_MAX_DIGEST_SIZE 64
+/* AES256 has 16byte blocks == 128 bits */
+#define RANDOM_MAX_BLOCK_SIZE 16
+/* AES256 has 32byte keys == 256 bits */
+#define RANDOM_MAX_KEY_SIZE 32
+
+/*
+ * The minimum number of bits of entropy before we wake up a read on
+ * /dev/random. We also wait for reseed_count>0 and we do a
+ * random_reseed() once we do wake up.
+ */
+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 = DEFAULT_POOL_SIZE * 7;
+
+static DEFINE_PER_CPU(int, trickle_count) = 0;
+
+#define POOLBYTES\
+ ( (1<<random_state->pool_number) * random_state->digestsize )
+#define POOLBITS ( POOLBYTES * 8 )
+
+/*
+ * Linux 2.2 compatibility
+ */
+#ifndef DECLARE_WAITQUEUE
+#define DECLARE_WAITQUEUE(WAIT, PTR) struct wait_queue WAIT = { PTR, NULL }
+#endif
+#ifndef DECLARE_WAIT_QUEUE_HEAD
+#define DECLARE_WAIT_QUEUE_HEAD(WAIT) struct wait_queue *WAIT
+#endif
+
+/*
+ * Static global variables
+ */
+static struct entropy_store *random_state; /* The default global store */
+static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
+static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
+
+/*
+ * Forward procedure declarations
+ */
+#ifdef CONFIG_SYSCTL
+static void sysctl_init_random(struct entropy_store *random_state);
+#endif
+
+/*****************************************************************
+ *
+ * Utility functions, with some ASM defined functions for speed
+ * purposes
+ *
+ *****************************************************************/
+
+/*
+ * More asm magic....
+ *
+ * For entropy estimation, we need to do an integral base 2
+ * logarithm.
+ *
+ * Note the "12bits" suffix - this is used for numbers between
+ * 0 and 4095 only. This allows a few shortcuts.
+ */
+#if 0 /* Slow but clear version */
+static inline __u32 int_ln_12bits(__u32 word)
+{
+ __u32 nbits = 0;
+
+ while (word >>= 1)
+ nbits++;
+ return nbits;
+}
+#else /* Faster (more clever) version, courtesy Colin Plumb */
+static inline __u32 int_ln_12bits(__u32 word)
+{
+ /* Smear msbit right to make an n-bit mask */
+ word |= word >> 8;
+ word |= word >> 4;
+ word |= word >> 2;
+ word |= word >> 1;
+ /* Remove one bit to make this a logarithm */
+ word >>= 1;
+ /* Count the bits set in the word */
+ word -= (word >> 1) & 0x555;
+ word = (word & 0x333) + ((word >> 2) & 0x333);
+ word += (word >> 4);
+ word += (word >> 8);
+ return word & 15;
+}
+#endif
+
+#if 0
+ #define DEBUG_ENT(fmt, arg...) printk("random: " fmt, ## arg)
+#else
+ #define DEBUG_ENT(fmt, arg...) do {} while (0)
+#endif
+#if 0
+ #define STATS_ENT(fmt, arg...) printk("random-stats: " fmt, ## arg)
+#else
+ #define STATS_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 {
+ const char *digestAlgo;
+ unsigned int digestsize;
+ struct crypto_tfm *pools[1<<DEFAULT_POOL_NUMBER];
+ /* optional, handy for statistics */
+ unsigned int pools_bytes[1<<DEFAULT_POOL_NUMBER];
+
+ const char *cipherAlgo;
+ /* the key */
+ unsigned char key[RANDOM_MAX_DIGEST_SIZE];
+ unsigned int keysize;
+ /* the CTR value */
+ unsigned char iv[16];
+ unsigned int blocksize;
+ struct crypto_tfm *cipher;
+
+ /* 2^pool_number # of pools */
+ unsigned int pool_number;
+ /* current pool to add into */
+ unsigned int pool_index;
+ /* size of the first pool */
+ unsigned int pool0_len;
+ /* number of time we have reset */
+ unsigned int reseed_count;
+ /* time in msec of the last reseed */
+ time_t reseed_time;
+ /* digest used during random_reseed() */
+ struct crypto_tfm *reseedHash;
+ /* cipher used for network randomness */
+ struct crypto_tfm *networkCipher;
+ /* flag indicating if networkCipher has been seeded */
+ char networkCipher_ready;
+
+ /* read-write data: */
+ spinlock_t lock ____cacheline_aligned_in_smp;
+ int entropy_count;
+};
+
+/*
+ * Initialize the entropy store. The input argument is the size of
+ * the random pool.
+ *
+ * Returns an negative error if there is a problem.
+ */
+static int create_entropy_store(int poolnum, struct entropy_store **ret_bucket)
+{
+ struct entropy_store *r;
+ unsigned long pool_number;
+ int keysize, i, j;
+
+ pool_number = poolnum;
+
+ r = kmalloc(sizeof(struct entropy_store), GFP_KERNEL);
+ if (!r) {
+ return -ENOMEM;
+ }
+
+ memset (r, 0, sizeof(struct entropy_store));
+ r->pool_number = pool_number;
+ r->digestAlgo = RANDOM_DEFAULT_DIGEST_ALGO;
+
+DEBUG_ENT("create_entropy_store() pools=%u index=%u\n",
+ 1<<pool_number, r->pool_index);
+ for (i=0; i<(1<<pool_number); i++) {
+DEBUG_ENT("create_entropy_store() i=%i index=%u\n", i, r->pool_index);
+ r->pools[i] = crypto_alloc_tfm(r->digestAlgo, 0);
+ if (r->pools[i] == NULL) {
+ for (j=0; j<i; j++) {
+ if (r->pools[j] != NULL) {
+ kfree(r->pools[j]);
+ }
+ }
+ kfree(r);
+ return -ENOMEM;
+ }
+ crypto_digest_init( r->pools[i] );
+ }
+ r->lock = SPIN_LOCK_UNLOCKED;
+ *ret_bucket = r;
+
+ r->cipherAlgo = RANDOM_DEFAULT_CIPHER_ALGO;
+ if ((r->cipher=crypto_alloc_tfm(r->cipherAlgo, 0)) == NULL) {
+ return -ENOMEM;
+ }
+
+ /* If the HASH's output is greater then the cipher's keysize, truncate
+ * to the cipher's keysize */
+ keysize = crypto_tfm_alg_max_keysize(r->cipher);
+ r->digestsize = crypto_tfm_alg_digestsize(r->pools[0]);
+ r->blocksize = crypto_tfm_alg_blocksize(r->cipher);
+
+ r->keysize = (keysize < r->digestsize) ? keysize : r->digestsize;
+DEBUG_ENT("create_RANDOM %u %u %u\n", keysize, r->digestsize, r->keysize);
+
+ if (crypto_cipher_setkey(r->cipher, r->key, r->keysize)) {
+ return -EINVAL;
+ }
+
+ /* digest used duing random-reseed() */
+ if ((r->reseedHash=crypto_alloc_tfm(r->digestAlgo, 0)) == NULL) {
+ return -ENOMEM;
+ }
+ /* cipher used for network randomness */
+ if ((r->networkCipher=crypto_alloc_tfm(r->cipherAlgo, 0)) == NULL) {
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+/*
+ * 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.
+ */
+static void add_entropy_words(struct entropy_store *r, const __u32 *in,
+ int nwords, int dst_pool)
+{
+ unsigned long flags;
+ struct scatterlist sg[1];
+ static unsigned int totalBytes=0;
+
+ if (r == NULL) {
+ return;
+ }
+
+ spin_lock_irqsave(&r->lock, flags);
+
+ totalBytes += nwords * sizeof(__u32);
+
+ sg[0].page = virt_to_page(in);
+ sg[0].offset = offset_in_page(in);
+ sg[0].length = nwords*sizeof(__u32);
+
+ if (dst_pool == -1) {
+ r->pools_bytes[r->pool_index] += nwords * sizeof(__u32);
+ crypto_digest_update(r->pools[r->pool_index], sg, 1);
+ if (r->pool_index == 0) {
+ r->pool0_len += nwords*sizeof(__u32);
+ }
+ /* idx = (idx + 1) mod ( (2^N)-1 ) */
+ r->pool_index = (r->pool_index + 1)
+ & ((1<<random_state->pool_number)-1);
+ } else {
+ /* Let's make sure nothing mean is happening... */
+ dst_pool &= (1<<random_state->pool_number) - 1;
+ r->pools_bytes[dst_pool] += nwords * sizeof(__u32);
+ crypto_digest_update(r->pools[dst_pool], sg, 1);
+ }
+DEBUG_ENT("r->pool0_len = %u\n", r->pool0_len);
+
+
+ spin_unlock_irqrestore(&r->lock, flags);
+DEBUG_ENT("0 add_entropy_words() nwords=%u pool[i].bytes=%u total=%u\n",
+ nwords, r->pools_bytes[r->pool_index], totalBytes);
+}
+
+/*
+ * 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 > POOLBITS) {
+ r->entropy_count = POOLBITS;
+ } else {
+ r->entropy_count += nbits;
+ if (nbits)
+ DEBUG_ENT("%04d : added %d bits\n",
+ r->entropy_count,
+ nbits);
+ }
+
+ spin_unlock_irqrestore(&r->lock, flags);
+}
+
+/**********************************************************************
+ *
+ * Entropy batch input management
+ *
+ * We batch entropy to be added to avoid increasing interrupt latency
+ *
+ **********************************************************************/
+
+struct sample {
+ __u32 data[2];
+ int credit;
+};
+
+static struct sample *batch_entropy_pool, *batch_entropy_copy;
+static int batch_head, batch_tail;
+static spinlock_t batch_lock = SPIN_LOCK_UNLOCKED;
+
+static int batch_max;
+static void batch_entropy_process(void *private_);
+static DECLARE_WORK(batch_work, batch_entropy_process, NULL);
+
+/* note: the size must be a power of 2 */
+static int __init batch_entropy_init(int size, struct entropy_store *r)
+{
+ batch_entropy_pool = kmalloc(size*sizeof(struct sample), GFP_KERNEL);
+ if (!batch_entropy_pool)
+ return -1;
+ batch_entropy_copy = kmalloc(size*sizeof(struct sample), GFP_KERNEL);
+ if (!batch_entropy_copy) {
+ kfree(batch_entropy_pool);
+ return -1;
+ }
+ batch_head = batch_tail = 0;
+ batch_work.data = r;
+ batch_max = size;
+ return 0;
+}
+
+/*
+ * Changes to the entropy data is put into a queue rather than being added to
+ * the entropy counts directly. This is presumably to avoid doing heavy
+ * hashing calculations during an interrupt in add_timer_randomness().
+ * Instead, the entropy is only added to the pool by keventd.
+ */
+void batch_entropy_store(u32 a, u32 b, int num)
+{
+ int new;
+ unsigned long flags;
+
+ if (!batch_max)
+ return;
+
+ spin_lock_irqsave(&batch_lock, flags);
+
+ batch_entropy_pool[batch_head].data[0] = a;
+ batch_entropy_pool[batch_head].data[1] = b;
+ batch_entropy_pool[batch_head].credit = num;
+
+ if (((batch_head - batch_tail) & (batch_max-1)) >= (batch_max / 2)) {
+ /*
+ * Schedule it for the next timer tick:
+ */
+ schedule_delayed_work(&batch_work, 1);
+ }
+
+ new = (batch_head+1) & (batch_max-1);
+ if (new == batch_tail) {
+ DEBUG_ENT("batch entropy buffer full\n");
+ } else {
+ batch_head = new;
+ }
+
+ spin_unlock_irqrestore(&batch_lock, flags);
+}
+
+EXPORT_SYMBOL(batch_entropy_store);
+
+/*
+ * Flush out the accumulated entropy operations, adding entropy to the passed
+ * store (normally random_state). If that store has enough entropy, alternate
+ * between randomizing the data of the primary and secondary stores.
+ */
+static void batch_entropy_process(void *private_)
+{
+ int max_entropy = POOLBITS;
+ unsigned head, tail;
+
+ /* Mixing into the pool is expensive, so copy over the batch
+ * data and release the batch lock. The pool is at least half
+ * full, so don't worry too much about copying only the used
+ * part.
+ */
+ spin_lock_irq(&batch_lock);
+
+ memcpy(batch_entropy_copy, batch_entropy_pool,
+ batch_max*sizeof(struct sample));
+
+ head = batch_head;
+ tail = batch_tail;
+ batch_tail = batch_head;
+
+ spin_unlock_irq(&batch_lock);
+
+ while (head != tail) {
+ if (random_state->entropy_count >= max_entropy) {
+ max_entropy = POOLBITS;
+ }
+ /*
+ * Only credit if we're feeding into pool[0]
+ * Otherwise we'd be assuming entropy in pool[31] would be
+ * usable when we read. This is conservative, but it'll
+ * not over-credit our entropy estimate for users of
+ * /dev/random, /dev/urandom will not be effected.
+ */
+ if (random_state->pool_index == 0) {
+ credit_entropy_store(random_state,
+ batch_entropy_copy[tail].credit);
+ }
+ add_entropy_words(random_state,
+ batch_entropy_copy[tail].data, 2, -1);
+;
+
+ tail = (tail+1) & (batch_max-1);
+ }
+ if (random_state->entropy_count >= random_read_wakeup_thresh
+ && random_state->reseed_count != 0)
+ wake_up_interruptible(&random_read_wait);
+}
+
+/*********************************************************************
+ *
+ * Entropy input management
+ *
+ *********************************************************************/
+
+/* There is one of these per entropy source */
+struct timer_rand_state {
+ __u32 last_time;
+ __s32 last_delta,last_delta2;
+ int dont_count_entropy:1;
+};
+
+static struct timer_rand_state keyboard_timer_state;
+static struct timer_rand_state mouse_timer_state;
+static struct timer_rand_state extract_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.
+ * On the i386, this is assumed to be at most 16 bits, and the high bits
+ * are used for a high-resolution timer.
+ *
+ */
+static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
+{
+ __u32 time;
+ __s32 delta, delta2, delta3;
+ int entropy = 0;
+
+ /* if over the trickle threshold, use only 1 in 4096 samples */
+ if ( random_state->entropy_count > trickle_thresh &&
+ (__get_cpu_var(trickle_count)++ & 0xfff))
+ return;
+
+#if defined (__i386__) || defined (__x86_64__)
+ if (cpu_has_tsc) {
+ __u32 high;
+ rdtsc(time, high);
+ num ^= high;
+ } else {
+ time = jiffies;
+ }
+#elif defined (__sparc_v9__)
+ unsigned long tick = tick_ops->get_tick();
+
+ time = (unsigned int) tick;
+ num ^= (tick >> 32UL);
+#else
+ time = jiffies;
+#endif
+
+ /*
+ * 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 = time - state->last_time;
+ state->last_time = time;
+
+ 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.
+ */
+ delta >>= 1;
+ delta &= (1 << 12) - 1;
+
+ entropy = int_ln_12bits(delta);
+ }
+ batch_entropy_store(num, time, entropy);
+}
+
+void add_keyboard_randomness(unsigned char scancode)
+{
+ static unsigned char last_scancode;
+ /* ignore autorepeat (multiple key down w/o key up) */
+ if (scancode != last_scancode) {
+ last_scancode = scancode;
+ add_timer_randomness(&keyboard_timer_state, scancode);
+ }
+}
+
+EXPORT_SYMBOL(add_keyboard_randomness);
+
+void add_mouse_randomness(__u32 mouse_data)
+{
+ add_timer_randomness(&mouse_timer_state, mouse_data);
+}
+
+EXPORT_SYMBOL(add_mouse_randomness);
+
+void add_interrupt_randomness(int irq)
+{
+ if (irq >= NR_IRQS || irq_timer_state[irq] == 0)
+ return;
+
+ add_timer_randomness(irq_timer_state[irq], 0x100+irq);
+}
+
+EXPORT_SYMBOL(add_interrupt_randomness);
+
+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+MKDEV(disk->major, disk->first_minor));
+}
+
+EXPORT_SYMBOL(add_disk_randomness);
+
+/*********************************************************************
+ *
+ * Entropy extraction routines
+ *
+ *********************************************************************/
+
+#define EXTRACT_ENTROPY_USER 1
+#define EXTRACT_ENTROPY_LIMIT 4
+
+static ssize_t extract_entropy(struct entropy_store *r, void * buf,
+ size_t nbytes, int flags);
+
+static inline void increment_iv(unsigned char *iv, const unsigned int IVsize) {
+ switch (IVsize) {
+ case 8:
+ if (++((u32*)iv)[0])
+ ++((u32*)iv)[1];
+ break;
+
+ case 16:
+ if (++((u32*)iv)[0])
+ if (++((u32*)iv)[1])
+ if (++((u32*)iv)[2])
+ ++((u32*)iv)[3];
+ break;
+
+ default:
+ {
+ int i;
+ for (i=0; i<IVsize; i++)
+ if (++iv[i])
+ break;
+ }
+ break;
+ }
+}
+
+/*
+ * Fortuna's Reseed
+ *
+ * Key' = hash(Key || hash(pool[a0]) || hash(pool[a1]) || ...)
+ * where {a0,a1,...} are facators of r->reseed_count+1 which are of the form
+ * 2^j, 0<=j.
+ * Prevents backtracking attacks and with event inputs, supports forward
+ * secrecy
+ */
+static void random_reseed(struct entropy_store *r, size_t nbytes, int flags) {
+ struct scatterlist sg[1];
+ unsigned int i, deduct;
+ unsigned char tmp[RANDOM_MAX_DIGEST_SIZE];
+ unsigned long cpuflags;
+
+ deduct = (r->keysize < r->digestsize) ? r->keysize : r->digestsize;
+
+ /* Hold lock while accounting */
+ spin_lock_irqsave(&r->lock, cpuflags);
+
+ DEBUG_ENT("%04d : trying to extract %d bits\n",
+ random_state->entropy_count,
+ deduct * 8);
+
+ /*
+ * Don't extract more data than in the entropy in the pooling system
+ */
+ if (flags & EXTRACT_ENTROPY_LIMIT && nbytes >= r->entropy_count / 8) {
+ nbytes = r->entropy_count / 8;
+ }
+
+ if (deduct*8 <= r->entropy_count) {
+ r->entropy_count -= deduct*8;
+ } else {
+ r->entropy_count = 0;
+ }
+
+ if (r->entropy_count < random_write_wakeup_thresh)
+ wake_up_interruptible(&random_write_wait);
+
+ DEBUG_ENT("%04d : debiting %d bits%s\n",
+ random_state->entropy_count,
+ deduct * 8,
+ flags & EXTRACT_ENTROPY_LIMIT ? "" : " (unlimited)");
+
+ r->reseed_count++;
+ r->pool0_len = 0;
+
+ /* Entropy accounting done, release lock. */
+ spin_unlock_irqrestore(&r->lock, cpuflags);
+
+ DEBUG_ENT("random_reseed count=%u\n", r->reseed_count);
+
+ crypto_digest_init(r->reseedHash);
+
+ sg[0].page = virt_to_page(r->key);
+ sg[0].offset = offset_in_page(r->key);
+ sg[0].length = r->keysize;
+ crypto_digest_update(r->reseedHash, sg, 1);
+
+#define TESTBIT(VAL, N)\
+ ( ((VAL) >> (N)) & 1 )
+ for (i=0; i<(1<<r->pool_number); i++) {
+ /* using pool[i] if r->reseed_count is divisible by 2^i
+ * since 2^0 == 1, we always use pool[0]
+ */
+ if ( (i==0) || TESTBIT(r->reseed_count,i)==0 ) {
+ crypto_digest_final(r->pools[i], tmp);
+
+ sg[0].page = virt_to_page(tmp);
+ sg[0].offset = offset_in_page(tmp);
+ sg[0].length = r->keysize;
+ crypto_digest_update(r->reseedHash, sg, 1);
+
+ crypto_digest_init(r->pools[i]);
+ /* Each pool carries its past state forward */
+ crypto_digest_update(r->pools[i], sg, 1);
+ } else {
+ /* pool j is only used once every 2^j times */
+ break;
+ }
+ }
+#undef TESTBIT
+
+ crypto_digest_final(r->reseedHash, r->key);
+ crypto_cipher_setkey(r->cipher, r->key, r->keysize);
+ increment_iv(r->iv, r->blocksize);
+}
+
+static inline time_t get_msectime(void) {
+ struct timeval tv;
+ do_gettimeofday(&tv);
+ return (tv.tv_sec * 1000) + (tv.tv_usec / 1000);
+}
+
+/*
+ * This function extracts randomness from the "entropy pool", and
+ * returns it in a buffer. This function computes how many remaining
+ * bits of entropy are left in the pool, but it does not restrict the
+ * number of bytes that are actually obtained. If the EXTRACT_ENTROPY_USER
+ * flag is given, then the buf pointer is assumed to be in user space.
+ */
+static ssize_t extract_entropy(struct entropy_store *r, void * buf,
+ size_t nbytes, int flags)
+{
+ ssize_t ret, i;
+ __u32 tmp[RANDOM_MAX_BLOCK_SIZE];
+ struct scatterlist sgiv[1], sgtmp[1];
+ time_t nowtime;
+
+ /* Redundant, but just in case... */
+ if (r->entropy_count > POOLBITS)
+ r->entropy_count = POOLBITS;
+
+ /*
+ * To keep the possibility of collisions down, limit the number of
+ * output bytes per block cipher key.
+ */
+ if (RANDOM_MAX_EXTRACT_SIZE < nbytes)
+ nbytes = RANDOM_MAX_EXTRACT_SIZE;
+
+ if (flags & EXTRACT_ENTROPY_LIMIT) {
+ /* if in blocking, only output upto the entropy estimate */
+ if (r->entropy_count/8 < nbytes)
+ nbytes = r->entropy_count/8;
+ /*
+ * if blocking and there is no entropy by our estimate,
+ * break out now.
+ */
+ if (nbytes == 0)
+ return 0;
+ }
+
+ /*
+ * If reading in non-blocking mode, pace ourselves in using up the pool
+ * system's entropy.
+ */
+ if (! (flags & EXTRACT_ENTROPY_LIMIT) ) {
+ nowtime = get_msectime();
+ if (r->pool0_len > 64
+ && (nowtime - r->reseed_time) > RANDOM_RESEED_INTERVAL) {
+ random_reseed(r, nbytes, flags);
+ r->reseed_time = nowtime;
+ }
+ }
+
+ sgiv[0].page = virt_to_page(r->iv);
+ sgiv[0].offset = offset_in_page(r->iv);
+ sgiv[0].length = r->blocksize;
+ sgtmp[0].page = virt_to_page(tmp);
+ sgtmp[0].offset = offset_in_page(tmp);
+ sgtmp[0].length = r->blocksize;
+
+ ret = 0;
+ while (nbytes) {
+ /*
+ * Check if we need to break out or reschedule....
+ */
+ if ((flags & EXTRACT_ENTROPY_USER) && need_resched()) {
+ if (signal_pending(current)) {
+ if (ret == 0)
+ ret = -ERESTARTSYS;
+ break;
+ }
+
+ DEBUG_ENT("%04d : extract sleeping (%d bytes left)\n",
+ random_state->entropy_count,
+ nbytes);
+
+ schedule();
+
+ /*
+ * when we wakeup, there will be more data in our
+ * pooling system so we will reseed
+ */
+ nowtime = get_msectime();
+ if (r->pool0_len > 64
+ && (nowtime-r->reseed_time) > RANDOM_RESEED_INTERVAL) {
+ random_reseed(r, nbytes, flags);
+ r->reseed_time = nowtime;
+ }
+
+ DEBUG_ENT("%04d : extract woke up\n",
+ random_state->entropy_count);
+ }
+
+ /*
+ * Reading from /dev/random, we limit this to the amount
+ * of entropy to deduct from our estimate. This estimate is
+ * most naturally updated from inside Fortuna-reseed, so we
+ * limit our block size here.
+ *
+ * At most, Fortuna will use e=min(r->digestsize, r->keysize) of
+ * entropy to reseed.
+ */
+ if (flags & EXTRACT_ENTROPY_LIMIT) {
+ r->reseed_time = get_msectime();
+ random_reseed(r, nbytes, flags);
+ }
+
+ crypto_cipher_encrypt(r->cipher, sgtmp, sgiv, r->blocksize);
+ increment_iv(r->iv, r->blocksize);
+
+ /* Copy data to destination buffer */
+ i = (nbytes < r->blocksize) ? nbytes : r->blocksize;
+ if (flags & EXTRACT_ENTROPY_USER) {
+ i -= copy_to_user(buf, (__u8 const *)tmp, i);
+ if (!i) {
+ ret = -EFAULT;
+ break;
+ }
+ } else
+ memcpy(buf, (__u8 const *)tmp, i);
+ nbytes -= i;
+ buf += i;
+ ret += i;
+ }
+
+ /* generate a new key */
+ /* take into account the possibility that keysize >= blocksize */
+ for (i=0; i+r->blocksize<=r->keysize; i+=r->blocksize) {
+ sgtmp[0].page = virt_to_page( r->key+i );
+ sgtmp[0].offset = offset_in_page( r->key+i );
+ sgtmp[0].length = r->blocksize;
+ crypto_cipher_encrypt(r->cipher, sgtmp, sgiv, 1);
+ increment_iv(r->iv, r->blocksize);
+ }
+ sgtmp[0].page = virt_to_page( r->key+i );
+ sgtmp[0].offset = offset_in_page( r->key+i );
+ sgtmp[0].length = r->blocksize-i;
+ crypto_cipher_encrypt(r->cipher, sgtmp, sgiv, 1);
+ increment_iv(r->iv, r->blocksize);
+
+ if (crypto_cipher_setkey(r->cipher, r->key, r->keysize)) {
+ return -EINVAL;
+ }
+
+ /* 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)
+{
+ if (random_state)
+ extract_entropy(random_state, (char *) buf, nbytes, 0);
+ else
+ printk(KERN_NOTICE "get_random_bytes called before "
+ "random driver initialization\n");
+}
+
+EXPORT_SYMBOL(get_random_bytes);
+
+/*********************************************************************
+ *
+ * Functions to interface with Linux
+ *
+ *********************************************************************/
+
+/*
+ * Initialize the random pool with standard stuff.
+ * This is not secure random data, but it can't hurt us and people scream
+ * when you try to remove it.
+ *
+ * NOTE: This is an OS-dependent function.
+ */
+static void init_std_data(struct entropy_store *r)
+{
+ struct timeval tv;
+ __u32 words[2];
+ char *p;
+ int i;
+
+ do_gettimeofday(&tv);
+ words[0] = tv.tv_sec;
+ words[1] = tv.tv_usec;
+ add_entropy_words(r, words, 2, -1);
+
+ /*
+ * This doesn't lock system.utsname. However, we are generating
+ * entropy so a race with a name set here is fine.
+ */
+ p = (char *) &system_utsname;
+ for (i = sizeof(system_utsname) / sizeof(words); i; i--) {
+ memcpy(words, p, sizeof(words));
+ add_entropy_words(r, words, sizeof(words)/4, -1);
+ p += sizeof(words);
+ }
+}
+
+static int __init rand_initialize(void)
+{
+ int i;
+
+ if (create_entropy_store(DEFAULT_POOL_NUMBER, &random_state))
+ goto err;
+ if (batch_entropy_init(BATCH_ENTROPY_SIZE, random_state))
+ goto err;
+ init_std_data(random_state);
+#ifdef CONFIG_SYSCTL
+ sysctl_init_random(random_state);
+#endif
+ for (i = 0; i < NR_IRQS; i++)
+ irq_timer_state[i] = NULL;
+ memset(&keyboard_timer_state, 0, sizeof(struct timer_rand_state));
+ memset(&mouse_timer_state, 0, sizeof(struct timer_rand_state));
+ memset(&extract_timer_state, 0, sizeof(struct timer_rand_state));
+ extract_timer_state.dont_count_entropy = 1;
+ return 0;
+err:
+ return -1;
+}
+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)
+{
+ DECLARE_WAITQUEUE(wait, current);
+ ssize_t n, retval = 0, count = 0;
+
+ if (nbytes == 0)
+ return 0;
+
+ while (nbytes > 0) {
+ n = nbytes;
+
+ DEBUG_ENT("%04d : reading %d bits, p: %d s: %d\n",
+ random_state->entropy_count,
+ n*8, random_state->entropy_count,
+ random_state->entropy_count);
+
+ n = extract_entropy(random_state, buf, n,
+ EXTRACT_ENTROPY_USER |
+ EXTRACT_ENTROPY_LIMIT);
+
+ DEBUG_ENT("%04d : read got %d bits (%d needed, reseeds=%d)\n",
+ random_state->entropy_count,
+ random_state->reseed_count,
+ n*8, (nbytes-n)*8);
+
+ if (n == 0) {
+ if (file->f_flags & O_NONBLOCK) {
+ retval = -EAGAIN;
+ break;
+ }
+ if (signal_pending(current)) {
+ retval = -ERESTARTSYS;
+ break;
+ }
+
+ DEBUG_ENT("%04d : sleeping?\n",
+ random_state->entropy_count);
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ add_wait_queue(&random_read_wait, &wait);
+
+ if (random_state->entropy_count / 8 == 0
+ || random_state->reseed_count == 0)
+ schedule();
+
+ set_current_state(TASK_RUNNING);
+ remove_wait_queue(&random_read_wait, &wait);
+
+ DEBUG_ENT("%04d : waking up\n",
+ random_state->entropy_count);
+
+ 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)
+{
+ /* Don't return anything untill we've reseeded at least once */
+ if (random_state->reseed_count == 0)
+ return 0;
+
+ return extract_entropy(random_state, buf, nbytes,
+ EXTRACT_ENTROPY_USER);
+}
+
+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 (random_state->entropy_count >= random_read_wakeup_thresh)
+ mask |= POLLIN | POLLRDNORM;
+ if (random_state->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)
+{
+ static int idx = 0;
+ 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;
+
+ /*
+ * Use input data rotates though the pools independantly of
+ * system-events.
+ *
+ * idx = (idx + 1) mod ( (2^N)-1 )
+ */
+ idx = (idx + 1) & ((1<<random_state->pool_number)-1);
+ add_entropy_words(random_state, buf, bytes, idx);
+ }
+ if (p == buffer) {
+ return (ssize_t)ret;
+ } else {
+ file->f_dentry->d_inode->i_mtime = CURRENT_TIME;
+ mark_inode_dirty(file->f_dentry->d_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 = random_state->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(random_state, ent_count);
+ /*
+ * Wake up waiting processes if we have enough
+ * entropy.
+ */
+ if (random_state->entropy_count >= random_read_wakeup_thresh
+ && random_state->reseed_count != 0)
+ wake_up_interruptible(&random_read_wait);
+ return 0;
+ case RNDGETPOOL:
+ /* can't do this anymore */
+ 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(random_state, ent_count);
+ /*
+ * Wake up waiting processes if we have enough
+ * entropy.
+ */
+ if (random_state->entropy_count >= random_read_wakeup_thresh
+ && random_state->reseed_count != 0)
+ wake_up_interruptible(&random_read_wait);
+ return 0;
+ case RNDZAPENTCNT:
+ /* Can't do this anymore */
+ return 0;
+ case RNDCLEARPOOL:
+ /* Can't to this anymore */
+ 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 sysctl_poolsize;
+static int min_read_thresh, max_read_thresh;
+static int min_write_thresh, max_write_thresh;
+static char sysctl_bootid[16];
+
+static int proc_do_poolsize(ctl_table *table, int write, struct file *filp,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ int ret;
+
+ sysctl_poolsize = POOLBITS;
+
+ ret = proc_dointvec(table, write, filp, buffer, lenp, ppos);
+ if (ret || !write ||
+ (sysctl_poolsize == POOLBITS))
+ return ret;
+
+ return ret; /* can't change the pool size in fortuna */
+}
+
+static int poolsize_strategy(ctl_table *table, int __user *name, int nlen,
+ void __user *oldval, size_t __user *oldlenp,
+ void __user *newval, size_t newlen, void **context)
+{
+ int len;
+
+ sysctl_poolsize = POOLBITS;
+
+ /*
+ * We only handle the write case, since the read case gets
+ * handled by the default handler (and we don't care if the
+ * write case happens twice; it's harmless).
+ */
+ if (newval && newlen) {
+ len = newlen;
+ if (len > table->maxlen)
+ len = table->maxlen;
+ if (copy_from_user(table->data, newval, len))
+ return -EFAULT;
+ }
+
+ return 0;
+}
+
+/*
+ * 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;
+}
+
+ctl_table random_table[] = {
+ {
+ .ctl_name = RANDOM_POOLSIZE,
+ .procname = "poolsize",
+ .data = &sysctl_poolsize,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_do_poolsize,
+ .strategy = &poolsize_strategy,
+ },
+ {
+ .ctl_name = RANDOM_ENTROPY_COUNT,
+ .procname = "entropy_avail",
+ .maxlen = sizeof(int),
+ .mode = 0444,
+ .proc_handler = &proc_dointvec,
+ },
+ {
+ .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 = RANDOM_DIGEST_ALGO,
+ .procname = "digest_algo",
+ .maxlen = 16,
+ .mode = 0444,
+ .proc_handler = &proc_dostring,
+ },
+ {
+ .ctl_name = RANDOM_CIPHER_ALGO,
+ .procname = "cipher_algo",
+ .maxlen = 16,
+ .mode = 0444,
+ .proc_handler = &proc_dostring,
+ },
+ { .ctl_name = 0 }
+};
+
+static void sysctl_init_random(struct entropy_store *random_state)
+{
+ int i;
+
+ /* If the sys-admin doesn't want people to know how fast
+ * random events are happening, he can set the read-threshhold
+ * down to zero so /dev/random never blocks. Default is to block.
+ * This is for the paranoid loonies who think frequency analysis
+ * would lead to something.
+ */
+ min_read_thresh = 0;
+ min_write_thresh = 0;
+ max_read_thresh = max_write_thresh = POOLBITS;
+ for (i=0; random_table[i].ctl_name!=0; i++) {
+ switch (random_table[i].ctl_name) {
+ case RANDOM_ENTROPY_COUNT:
+ random_table[i].data = &random_state->entropy_count;
+ break;
+
+ case RANDOM_DIGEST_ALGO:
+ random_table[i].data = (void*)random_state->digestAlgo;
+ break;
+
+ case RANDOM_CIPHER_ALGO:
+ random_table[i].data = (void*)random_state->cipherAlgo;
+ break;
+
+ default:
+ break;
+ }
+ }
+}
+#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 encrypted
+ * 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, modified by Jean-Luc Cooke.
+ *
+ * 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. This was changed
+ * again by Jean-Luc Cooke to use AES256-CBC encryption which is faster
+ * still (see `/usr/bin/openssl speed md4 sha1 aes`)
+ */
+
+/* This should not be decreased so low that ISNs wrap too fast. */
+#define REKEY_INTERVAL 300
+/*
+ * 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 spinlock_t ip_lock = SPIN_LOCK_UNLOCKED;
+static unsigned int ip_cnt, network_count;
+
+static void __check_and_rekey(time_t time)
+{
+ u8 tmp[RANDOM_MAX_KEY_SIZE];
+ spin_lock_bh(&ip_lock);
+
+ get_random_bytes(tmp, random_state->keysize);
+ crypto_cipher_setkey(random_state->networkCipher,
+ (const u8*)tmp,
+ random_state->keysize);
+ random_state->networkCipher_ready = 1;
+ network_count = (ip_cnt & COUNT_MASK) << HASH_BITS;
+ mb();
+ ip_cnt++;
+
+ spin_unlock_bh(&ip_lock);
+ return;
+}
+
+static inline void check_and_rekey(time_t time)
+{
+ static time_t rekey_time=0;
+
+ rmb();
+ if (!rekey_time || (time - rekey_time) > REKEY_INTERVAL) {
+ __check_and_rekey(time);
+ rekey_time = time;
+ }
+
+ return;
+}
+
+#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;
+ u8 tmp[RANDOM_MAX_BLOCK_SIZE];
+ struct scatterlist sgtmp[1];
+
+ /*
+ * The procedure is the same as for IPv4, but addresses are longer.
+ * Thus we must use two AES operations.
+ */
+
+ do_gettimeofday(&tv); /* We need the usecs below... */
+ check_and_rekey(tv.tv_sec);
+
+ sgtmp[0].page = virt_to_page(tmp);
+ sgtmp[0].offset = offset_in_page(tmp);
+ sgtmp[0].length = random_state->blocksize;
+
+ /*
+ * AES256 is 2.5 times faster then MD4 by openssl tests.
+ * We can afford to encrypt 2 block in CBC with
+ * and IV={(sport)<<16 | dport, 0, 0, 0}
+ *
+ * seq = ct[0], ct = Enc-CBC(Key, {ports}, {daddr, saddr});
+ * = Enc(Key, saddr xor Enc(Key, daddr))
+ */
+
+ /* PT0 = daddr */
+ memcpy(tmp, daddr, random_state->blocksize);
+ /* IV = {ports,0,0,0} */
+ tmp[0] ^= (sport<<16) | dport;
+ crypto_cipher_encrypt(random_state->networkCipher, sgtmp, sgtmp, 1);
+ /* PT1 = saddr */
+ random_state->networkCipher->crt_cipher.cit_xor_block(tmp, (const u8*)saddr);
+ crypto_cipher_encrypt(random_state->networkCipher, sgtmp, sgtmp, 1);
+
+ seq = tmp[0];
+ seq += network_count;
+ seq += tv.tv_usec + tv.tv_sec*1000000;
+
+ return seq;
+}
+EXPORT_SYMBOL(secure_tcpv6_sequence_number);
+
+__u32 secure_ipv6_id(__u32 *daddr)
+{
+ u8 tmp[RANDOM_MAX_BLOCK_SIZE];
+ struct scatterlist sgtmp[1];
+
+ check_and_rekey(get_seconds());
+
+ memcpy(tmp, daddr, random_state->blocksize);
+ sgtmp[0].page = virt_to_page(tmp);
+ sgtmp[0].offset = offset_in_page(tmp);
+ sgtmp[0].length = random_state->blocksize;
+
+ /* id = tmp[0], tmp = Enc(Key, daddr); */
+ crypto_cipher_encrypt(random_state->networkCipher, sgtmp, sgtmp, 1);
+
+ return tmp[0];
+}
+
+EXPORT_SYMBOL(secure_ipv6_id);
+#endif
+
+
+__u32 secure_tcp_sequence_number(__u32 saddr, __u32 daddr,
+ __u16 sport, __u16 dport)
+{
+ struct timeval tv;
+ __u32 seq;
+ u8 tmp[RANDOM_MAX_BLOCK_SIZE];
+ struct scatterlist sgtmp[1];
+
+ /*
+ * Pick a random secret every REKEY_INTERVAL seconds.
+ */
+ do_gettimeofday(&tv); /* We need the usecs below... */
+ check_and_rekey(tv.tv_sec);
+
+ /*
+ * 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.
+ */
+ /*
+ * AES256 is 2.5 times faster then MD4 by openssl tests.
+ * We can afford to encrypt 1 block
+ *
+ * seq = ct[0], ct = Enc(Key, {(sport<<16)|dport, daddr, saddr, 0})
+ */
+
+ tmp[0] = (sport<<16) | dport;
+ tmp[1] = daddr;
+ tmp[2] = saddr;
+ tmp[3] = 0;
+ crypto_cipher_encrypt(random_state->networkCipher, sgtmp, sgtmp, 1);
+
+ seq = tmp[0];
+ seq += network_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?)
+ */
+ 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);
+
+/* The code below is shamelessly stolen from secure_tcp_sequence_number().
+ * All blames to Andrey V. Savochkin <saw@msu.ru>.
+ * Changed by Jean-Luc Cooke <jlcooke@certainkey.com> to use AES & C.A.P.I.
+ */
+__u32 secure_ip_id(__u32 daddr)
+{
+ struct scatterlist sgtmp[1];
+ u8 tmp[RANDOM_MAX_BLOCK_SIZE];
+
+ check_and_rekey(get_seconds());
+
+ /*
+ * Pick a unique starting offset for each IP destination.
+ * id = ct[0], ct = Enc(Key, {daddr,0,0,0});
+ */
+ tmp[0] = daddr;
+ tmp[1] = 0;
+ tmp[2] = 0;
+ tmp[3] = 0;
+ sgtmp[0].page = virt_to_page(tmp);
+ sgtmp[0].offset = offset_in_page(tmp);
+ sgtmp[0].length = random_state->blocksize;
+
+ crypto_cipher_encrypt(random_state->networkCipher, sgtmp, sgtmp, 1);
+
+ return tmp[0];
+}
+
+#ifdef CONFIG_SYN_COOKIES
+/*
+ * Secure SYN cookie computation. This is the algorithm worked out by
+ * Dan Bernstein and Eric Schenk.
+ *
+ * For linux I implement the 1 minute counter by looking at the jiffies clock.
+ * The count is passed in as a parameter, so this code doesn't much care.
+ *
+ * SYN cookie (and seq# & id#) Changed in 2004 by Jean-Luc Cooke
+ * <jlcooke@certainkey.com> to use the C.A.P.I. and AES256.
+ */
+
+#define COOKIEBITS 24 /* Upper bits store count */
+#define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
+
+__u32 secure_tcp_syn_cookie(__u32 saddr, __u32 daddr, __u16 sport,
+ __u16 dport, __u32 sseq, __u32 count, __u32 data)
+{
+ struct scatterlist sg[1];
+ __u32 tmp[4];
+
+ /*
+ * Compute the secure sequence number.
+ *
+ * Output is the 32bit tag of a CBC-MAC of
+ * PT={count,0,0,0} with IV={addr,daddr,sport|dport,sseq}
+ * cookie = {<8bit count>,
+ * truncate_24bit(
+ * Encrypt(Sec, {saddr,daddr,sport|dport,sseq})
+ * )
+ * }
+ *
+ * DJB wrote (http://cr.yp.to/syncookies/archive) about how to do this
+ * with hash algorithms.
+ * - we can replace two SHA1s used in the previous kernel with 1 AES
+ * and make things 5x faster
+ * - I'd like to propose we remove the use of two whittenings with a
+ * single operation since we were only using addition modulo 2^32 of
+ * all these values anyways. Not to mention the hashs differ only in
+ * that the second processes more data... why drop the first hash?
+ * We did learn that addition is commutative and associative long ago.
+ * - by replacing two SHA1s and addition modulo 2^32 with encryption of
+ * a 32bit value using CAPI we've made it 1,000,000,000 times easier
+ * to understand what is going on.
+ */
+
+ tmp[0] = saddr;
+ tmp[1] = daddr;
+ tmp[2] = (sport << 16) + dport;
+ tmp[3] = sseq;
+
+ sg[0].page = virt_to_page(tmp);
+ sg[0].offset = offset_in_page(tmp);
+ sg[0].length = random_state->blocksize;
+ if (!random_state->networkCipher_ready) {
+ check_and_rekey(get_seconds());
+ }
+ /* tmp[]/sg[0] = Enc(Sec, {saddr,daddr,sport|dport,sseq}) */
+ crypto_cipher_encrypt(random_state->networkCipher, sg, sg, 1);
+
+ /* cookie = CTR encrypt of 8-bit-count and 24-bit-data */
+ return tmp[0] ^ ( (count << COOKIEBITS) | (data & COOKIEMASK) );
+}
+
+/*
+ * This retrieves the small "data" value from the syncookie.
+ * If the syncookie is bad, the data returned will be out of
+ * range. This must be checked by the caller.
+ *
+ * The count value used to generate the cookie must be within
+ * "maxdiff" if the current (passed-in) "count". The return value
+ * is (__u32)-1 if this test fails.
+ */
+__u32 check_tcp_syn_cookie(__u32 cookie, __u32 saddr, __u32 daddr, __u16 sport,
+ __u16 dport, __u32 sseq, __u32 count, __u32 maxdiff)
+{
+ struct scatterlist sg[1];
+ __u32 tmp[4], thiscount, diff;
+
+ if (random_state == NULL || !random_state->networkCipher_ready)
+ return (__u32)-1; /* Well, duh! */
+
+ tmp[0] = saddr;
+ tmp[1] = daddr;
+ tmp[2] = (sport << 16) + dport;
+ tmp[3] = sseq;
+ sg[0].page = virt_to_page(tmp);
+ sg[0].offset = offset_in_page(tmp);
+ sg[0].length = random_state->blocksize;
+ crypto_cipher_encrypt(random_state->networkCipher, sg, sg, 1);
+
+ /* CTR decrypt the cookie */
+ cookie ^= tmp[0];
+
+ /* top 8 bits are 'count' */
+ thiscount = cookie >> COOKIEBITS;
+
+ diff = count - thiscount;
+ if (diff >= maxdiff)
+ return (__u32)-1;
+
+ /* bottom 24 bits are 'data' */
+ return cookie & COOKIEMASK;
+}
+#endif