/*
* random.c -- A strong random number generator
*
* Version 1.00, last modified 26-May-96
*
* Copyright Theodore Ts'o, 1994, 1995, 1996. 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 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 ARE
* 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 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 MD5
* hash of the contents of the "entropy pool". The MD5 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 MD5 from its output. Even if it is possible to
* analyze MD5 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 MD5, 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);
* void add_blkdev_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 to
* regular, and hence predictable to an attacker. Disk interrupts are
* a better measure, since the timing of the disk interrupts are more
* unpredictable.
*
* add_blkdev_randomness() times the finishing time of block requests.
*
* 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..."
* # Carry a random seed from start-up to start-up
* # Load and then save 512 bytes, which is the size of the entropy pool
* if [ -f /etc/random-seed ]; then
* cat /etc/random-seed >/dev/urandom
* fi
* dd if=/dev/urandom of=/etc/random-seed count=1
*
* 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 512 bytes, which is the size of the entropy pool
* echo "Saving random seed..."
* dd if=/dev/urandom of=/etc/random-seed count=1
*
* For example, on many Linux systems, the appropriate scripts are
* usually /etc/rc.d/rc.local and /etc/rc.d/rc.0, respectively.
*
* 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 the 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 PGP 3.0 (under development). It has since
* been modified by myself to provide better mixing in the case where
* the input values to add_entropy_word() are mostly small numbers.
* 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.
*
* The code for MD5 transform was taken from Colin Plumb's
* implementation, which has been placed in the public domain. The
* MD5 cryptographic checksum was devised by Ronald Rivest, and is
* documented in RFC 1321, "The MD5 Message Digest Algorithm".
*
* 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/kernel.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/malloc.h>
#include <linux/random.h>
#include <asm/segment.h>
#include <asm/irq.h>
#include <asm/io.h>
/*
* Configuration information
*/
#undef RANDOM_BENCHMARK
#undef BENCHMARK_NOINT
/*
* The pool is stirred with a primitive polynomial of degree 128
* over GF(2), namely x^128 + x^99 + x^59 + x^31 + x^9 + x^7 + 1.
* For a pool of size 64, try x^64+x^62+x^38+x^10+x^6+x+1.
*/
#define POOLWORDS 128 /* Power of 2 - note that this is 32-bit words */
#define POOLBITS (POOLWORDS*32)
#if POOLWORDS == 128
#define TAP1 99 /* The polynomial taps */
#define TAP2 59
#define TAP3 31
#define TAP4 9
#define TAP5 7
#elif POOLWORDS == 64
#define TAP1 62 /* The polynomial taps */
#define TAP2 38
#define TAP3 10
#define TAP4 6
#define TAP5 1
#else
#error No primitive polynomial available for chosen POOLWORDS
#endif
/*
* The minimum number of bits to release a "wait on input". Should
* probably always be 8, since a /dev/random read can return a single
* byte.
*/
#define WAIT_INPUT_BITS 8
/*
* The limit number of bits under which to release a "wait on
* output". Should probably always be the same as WAIT_INPUT_BITS, so
* that an output wait releases when and only when a wait on input
* would block.
*/
#define WAIT_OUTPUT_BITS WAIT_INPUT_BITS
/* There is actually only one of these, globally. */
struct random_bucket {
unsigned add_ptr;
unsigned entropy_count;
int input_rotate;
__u32 *pool;
};
#ifdef RANDOM_BENCHMARK
/* For benchmarking only */
struct random_benchmark {
unsigned long long start_time;
int times; /* # of samples */
unsigned long min;
unsigned long max;
unsigned long accum; /* accumulator for average */
const char *descr;
int unit;
unsigned long flags;
};
#define BENCHMARK_INTERVAL 500
static void initialize_benchmark(struct random_benchmark *bench,
const char *descr, int unit);
static void begin_benchmark(struct random_benchmark *bench);
static void end_benchmark(struct random_benchmark *bench);
struct random_benchmark timer_benchmark;
#endif
/* There is one of these per entropy source */
struct timer_rand_state {
unsigned long last_time;
int last_delta,last_delta2;
int dont_count_entropy:1;
};
static struct random_bucket random_state;
static __u32 random_pool[POOLWORDS];
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];
static struct timer_rand_state *blkdev_timer_state[MAX_BLKDEV];
static struct wait_queue *random_wait;
static int random_read(struct inode * inode, struct file * file,
char * buf, int nbytes);
static int random_read_unlimited(struct inode * inode, struct file * file,
char * buf, int nbytes);
static int random_select(struct inode *inode, struct file *file,
int sel_type, select_table * wait);
static int random_write(struct inode * inode, struct file * file,
const char * buffer, int count);
static int random_ioctl(struct inode * inode, struct file * file,
unsigned int cmd, unsigned long arg);
static inline void fast_add_entropy_word(struct random_bucket *r,
const __u32 input);
static void add_entropy_word(struct random_bucket *r,
const __u32 input);
#ifndef MIN
#define MIN(a,b) (((a) < (b)) ? (a) : (b))
#endif
/*
* Unfortunately, while the GCC optimizer for the i386 understands how
* to optimize a static rotate left of x bits, it doesn't know how to
* deal with a variable rotate of x bits. So we use a bit of asm magic.
*/
#if (!defined (__i386__))
extern inline __u32 rotate_left(int i, __u32 word)
{
return (word << i) | (word >> (32 - i));
}
#else
extern inline __u32 rotate_left(int i, __u32 word)
{
__asm__("roll %%cl,%0"
:"=r" (word)
:"0" (word),"c" (i));
return word;
}
#endif
/*
* More asm magic....
*
* For entropy estimation, we need to do an integral base 2
* logarithm. By default, use an open-coded C version, although we do
* have a version which takes advantage of the Intel's x86's "bsr"
* instruction.
*/
#if (!defined (__i386__))
static inline __u32 int_ln(__u32 word)
{
__u32 nbits = 0;
while (1) {
word >>= 1;
if (!word)
break;
nbits++;
}
return nbits;
}
#else
static inline __u32 int_ln(__u32 word)
{
__asm__("bsrl %1,%0\n\t"
"jnz 1f\n\t"
"movl $0,%0\n"
"1:"
:"=r" (word)
:"r" (word));
return word;
}
#endif
/*
* Initialize the random pool with standard stuff.
*
* NOTE: This is an OS-dependent function.
*/
static void init_std_data(struct random_bucket *r)
{
__u32 word, *p;
int i;
struct timeval tv;
do_gettimeofday(&tv);
add_entropy_word(r, tv.tv_sec);
add_entropy_word(r, tv.tv_usec);
for (p = (__u32 *) &system_utsname,
i = sizeof(system_utsname) / sizeof(__u32);
i ; i--, p++) {
memcpy(&word, p, sizeof(__u32));
add_entropy_word(r, word);
}
}
/* Clear the entropy pool and associated counters. */
static void rand_clear_pool(void)
{
random_state.add_ptr = 0;
random_state.entropy_count = 0;
random_state.pool = random_pool;
random_state.input_rotate = 0;
memset(random_pool, 0, sizeof(random_pool));
init_std_data(&random_state);
}
void rand_initialize(void)
{
int i;
rand_clear_pool();
for (i = 0; i < NR_IRQS; i++)
irq_timer_state[i] = NULL;
for (i = 0; i < MAX_BLKDEV; i++)
blkdev_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));
#ifdef RANDOM_BENCHMARK
initialize_benchmark(&timer_benchmark, "timer", 0);
#endif
extract_timer_state.dont_count_entropy = 1;
random_wait = NULL;
}
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) {
irq_timer_state[irq] = state;
memset(state, 0, sizeof(struct timer_rand_state));
}
}
void rand_initialize_blkdev(int major, int mode)
{
struct timer_rand_state *state;
if (major >= MAX_BLKDEV || blkdev_timer_state[major])
return;
/*
* If kmalloc returns null, we just won't use that entropy
* source.
*/
state = kmalloc(sizeof(struct timer_rand_state), mode);
if (state) {
blkdev_timer_state[major] = state;
memset(state, 0, sizeof(struct timer_rand_state));
}
}
/*
* This function adds a byte into the entropy "pool". It does not
* update the entropy estimate. The caller must do this if appropriate.
*
* The pool is stirred with a primitive polynomial of degree 128
* over GF(2), namely x^128 + x^99 + x^59 + x^31 + x^9 + x^7 + 1.
* For a pool of size 64, try x^64+x^62+x^38+x^10+x^6+x+1.
*
* We rotate the input word by a changing number of bits, to help
* assure that all bits in the entropy get toggled. Otherwise, if we
* consistently feed the entropy pool small numbers (like jiffies and
* scancodes, for example), the upper bits of the entropy pool don't
* get affected. --- TYT, 10/11/95
*/
static inline void fast_add_entropy_word(struct random_bucket *r,
const __u32 input)
{
unsigned i;
int new_rotate;
__u32 w;
w = rotate_left(r->input_rotate, input);
i = r->add_ptr = (r->add_ptr - 1) & (POOLWORDS-1);
/*
* 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 = r->input_rotate + 14;
if (i)
new_rotate = r->input_rotate + 7;
r->input_rotate = new_rotate & 31;
/* XOR in the various taps */
w ^= r->pool[(i+TAP1)&(POOLWORDS-1)];
w ^= r->pool[(i+TAP2)&(POOLWORDS-1)];
w ^= r->pool[(i+TAP3)&(POOLWORDS-1)];
w ^= r->pool[(i+TAP4)&(POOLWORDS-1)];
w ^= r->pool[(i+TAP5)&(POOLWORDS-1)];
w ^= r->pool[i];
/* Rotate w left 1 bit (stolen from SHA) and store */
r->pool[i] = (w << 1) | (w >> 31);
}
/*
* For places where we don't need the inlined version
*/
static void add_entropy_word(struct random_bucket *r,
const __u32 input)
{
fast_add_entropy_word(r, input);
}
/*
* 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 random_bucket *r,
struct timer_rand_state *state, unsigned num)
{
int delta, delta2, delta3;
__u32 time;
#ifdef RANDOM_BENCHMARK
begin_benchmark(&timer_benchmark);
#endif
#if defined (__i386__)
if (x86_capability & 16) {
unsigned long low, high;
__asm__(".byte 0x0f,0x31"
:"=a" (low), "=d" (high));
time = (__u32) low;
num ^= (__u32) high;
} else {
time = jiffies;
}
#else
time = jiffies;
#endif
fast_add_entropy_word(r, (__u32) num);
fast_add_entropy_word(r, time);
/*
* Calculate number of bits of randomness we probably
* added. We take into account the first and second order
* deltas in order to make our estimate.
*/
if (!state->dont_count_entropy &&
(r->entropy_count < POOLBITS)) {
delta = time - state->last_time;
state->last_time = time;
if (delta < 0) delta = -delta;
delta2 = delta - state->last_delta;
state->last_delta = delta;
if (delta2 < 0) delta2 = -delta2;
delta3 = delta2 - state->last_delta2;
state->last_delta2 = delta2;
if (delta3 < 0) delta3 = -delta3;
delta = MIN(MIN(delta, delta2), delta3) >> 1;
/* Limit entropy estimate to 12 bits */
delta &= (1 << 12) - 1;
r->entropy_count += int_ln(delta);
/* Prevent overflow */
if (r->entropy_count > POOLBITS)
r->entropy_count = POOLBITS;
}
/* Wake up waiting processes, if we have enough entropy. */
if (r->entropy_count >= WAIT_INPUT_BITS)
wake_up_interruptible(&random_wait);
#ifdef RANDOM_BENCHMARK
end_benchmark(&timer_benchmark);
#endif
}
void add_keyboard_randomness(unsigned char scancode)
{
add_timer_randomness(&random_state, &keyboard_timer_state, scancode);
}
void add_mouse_randomness(__u32 mouse_data)
{
add_timer_randomness(&random_state, &mouse_timer_state, mouse_data);
}
void add_interrupt_randomness(int irq)
{
if (irq >= NR_IRQS || irq_timer_state[irq] == 0)
return;
add_timer_randomness(&random_state, irq_timer_state[irq], 0x100+irq);
}
void add_blkdev_randomness(int major)
{
if (major >= MAX_BLKDEV)
return;
if (blkdev_timer_state[major] == 0) {
rand_initialize_blkdev(major, GFP_ATOMIC);
if (blkdev_timer_state[major] == 0)
return;
}
add_timer_randomness(&random_state, blkdev_timer_state[major],
0x200+major);
}
#define USE_SHA
#ifdef USE_SHA
#define HASH_BUFFER_SIZE 5
#define HASH_TRANSFORM SHATransform
/*
* SHA transform algorithm, taken from code written by Peter Gutman,
* and apparently in the public domain.
*/
/* The SHA f()-functions. */
#define f1(x,y,z) ( z ^ ( x & ( y ^ z ) ) ) /* Rounds 0-19 */
#define f2(x,y,z) ( x ^ y ^ z ) /* Rounds 20-39 */
#define f3(x,y,z) ( ( x & y ) | ( z & ( x | y ) ) ) /* Rounds 40-59 */
#define f4(x,y,z) ( x ^ y ^ z ) /* Rounds 60-79 */
/* The SHA Mysterious Constants */
#define K1 0x5A827999L /* Rounds 0-19 */
#define K2 0x6ED9EBA1L /* Rounds 20-39 */
#define K3 0x8F1BBCDCL /* Rounds 40-59 */
#define K4 0xCA62C1D6L /* Rounds 60-79 */
#define ROTL(n,X) ( ( ( X ) << n ) | ( ( X ) >> ( 32 - n ) ) )
#define expand(W,i) ( W[ i & 15 ] = \
ROTL( 1, ( W[ i & 15 ] ^ W[ (i - 14) & 15 ] ^ \
W[ (i - 8) & 15 ] ^ W[ (i - 3) & 15 ] ) ) )
#define subRound(a, b, c, d, e, f, k, data) \
( e += ROTL( 5, a ) + f( b, c, d ) + k + data, b = ROTL( 30, b ) )
void SHATransform(__u32 *digest, __u32 *data)
{
__u32 A, B, C, D, E; /* Local vars */
__u32 eData[ 16 ]; /* Expanded data */
/* Set up first buffer and local data buffer */
A = digest[ 0 ];
B = digest[ 1 ];
C = digest[ 2 ];
D = digest[ 3 ];
E = digest[ 4 ];
memcpy( eData, data, 16*sizeof(__u32));
/* Heavy mangling, in 4 sub-rounds of 20 iterations each. */
subRound( A, B, C, D, E, f1, K1, eData[ 0 ] );
subRound( E, A, B, C, D, f1, K1, eData[ 1 ] );
subRound( D, E, A, B, C, f1, K1, eData[ 2 ] );
subRound( C, D, E, A, B, f1, K1, eData[ 3 ] );
subRound( B, C, D, E, A, f1, K1, eData[ 4 ] );
subRound( A, B, C, D, E, f1, K1, eData[ 5 ] );
subRound( E, A, B, C, D, f1, K1, eData[ 6 ] );
subRound( D, E, A, B, C, f1, K1, eData[ 7 ] );
subRound( C, D, E, A, B, f1, K1, eData[ 8 ] );
subRound( B, C, D, E, A, f1, K1, eData[ 9 ] );
subRound( A, B, C, D, E, f1, K1, eData[ 10 ] );
subRound( E, A, B, C, D, f1, K1, eData[ 11 ] );
subRound( D, E, A, B, C, f1, K1, eData[ 12 ] );
subRound( C, D, E, A, B, f1, K1, eData[ 13 ] );
subRound( B, C, D, E, A, f1, K1, eData[ 14 ] );
subRound( A, B, C, D, E, f1, K1, eData[ 15 ] );
subRound( E, A, B, C, D, f1, K1, expand( eData, 16 ) );
subRound( D, E, A, B, C, f1, K1, expand( eData, 17 ) );
subRound( C, D, E, A, B, f1, K1, expand( eData, 18 ) );
subRound( B, C, D, E, A, f1, K1, expand( eData, 19 ) );
subRound( A, B, C, D, E, f2, K2, expand( eData, 20 ) );
subRound( E, A, B, C, D, f2, K2, expand( eData, 21 ) );
subRound( D, E, A, B, C, f2, K2, expand( eData, 22 ) );
subRound( C, D, E, A, B, f2, K2, expand( eData, 23 ) );
subRound( B, C, D, E, A, f2, K2, expand( eData, 24 ) );
subRound( A, B, C, D, E, f2, K2, expand( eData, 25 ) );
subRound( E, A, B, C, D, f2, K2, expand( eData, 26 ) );
subRound( D, E, A, B, C, f2, K2, expand( eData, 27 ) );
subRound( C, D, E, A, B, f2, K2, expand( eData, 28 ) );
subRound( B, C, D, E, A, f2, K2, expand( eData, 29 ) );
subRound( A, B, C, D, E, f2, K2, expand( eData, 30 ) );
subRound( E, A, B, C, D, f2, K2, expand( eData, 31 ) );
subRound( D, E, A, B, C, f2, K2, expand( eData, 32 ) );
subRound( C, D, E, A, B, f2, K2, expand( eData, 33 ) );
subRound( B, C, D, E, A, f2, K2, expand( eData, 34 ) );
subRound( A, B, C, D, E, f2, K2, expand( eData, 35 ) );
subRound( E, A, B, C, D, f2, K2, expand( eData, 36 ) );
subRound( D, E, A, B, C, f2, K2, expand( eData, 37 ) );
subRound( C, D, E, A, B, f2, K2, expand( eData, 38 ) );
subRound( B, C, D, E, A, f2, K2, expand( eData, 39 ) );
subRound( A, B, C, D, E, f3, K3, expand( eData, 40 ) );
subRound( E, A, B, C, D, f3, K3, expand( eData, 41 ) );
subRound( D, E, A, B, C, f3, K3, expand( eData, 42 ) );
subRound( C, D, E, A, B, f3, K3, expand( eData, 43 ) );
subRound( B, C, D, E, A, f3, K3, expand( eData, 44 ) );
subRound( A, B, C, D, E, f3, K3, expand( eData, 45 ) );
subRound( E, A, B, C, D, f3, K3, expand( eData, 46 ) );
subRound( D, E, A, B, C, f3, K3, expand( eData, 47 ) );
subRound( C, D, E, A, B, f3, K3, expand( eData, 48 ) );
subRound( B, C, D, E, A, f3, K3, expand( eData, 49 ) );
subRound( A, B, C, D, E, f3, K3, expand( eData, 50 ) );
subRound( E, A, B, C, D, f3, K3, expand( eData, 51 ) );
subRound( D, E, A, B, C, f3, K3, expand( eData, 52 ) );
subRound( C, D, E, A, B, f3, K3, expand( eData, 53 ) );
subRound( B, C, D, E, A, f3, K3, expand( eData, 54 ) );
subRound( A, B, C, D, E, f3, K3, expand( eData, 55 ) );
subRound( E, A, B, C, D, f3, K3, expand( eData, 56 ) );
subRound( D, E, A, B, C, f3, K3, expand( eData, 57 ) );
subRound( C, D, E, A, B, f3, K3, expand( eData, 58 ) );
subRound( B, C, D, E, A, f3, K3, expand( eData, 59 ) );
subRound( A, B, C, D, E, f4, K4, expand( eData, 60 ) );
subRound( E, A, B, C, D, f4, K4, expand( eData, 61 ) );
subRound( D, E, A, B, C, f4, K4, expand( eData, 62 ) );
subRound( C, D, E, A, B, f4, K4, expand( eData, 63 ) );
subRound( B, C, D, E, A, f4, K4, expand( eData, 64 ) );
subRound( A, B, C, D, E, f4, K4, expand( eData, 65 ) );
subRound( E, A, B, C, D, f4, K4, expand( eData, 66 ) );
subRound( D, E, A, B, C, f4, K4, expand( eData, 67 ) );
subRound( C, D, E, A, B, f4, K4, expand( eData, 68 ) );
subRound( B, C, D, E, A, f4, K4, expand( eData, 69 ) );
subRound( A, B, C, D, E, f4, K4, expand( eData, 70 ) );
subRound( E, A, B, C, D, f4, K4, expand( eData, 71 ) );
subRound( D, E, A, B, C, f4, K4, expand( eData, 72 ) );
subRound( C, D, E, A, B, f4, K4, expand( eData, 73 ) );
subRound( B, C, D, E, A, f4, K4, expand( eData, 74 ) );
subRound( A, B, C, D, E, f4, K4, expand( eData, 75 ) );
subRound( E, A, B, C, D, f4, K4, expand( eData, 76 ) );
subRound( D, E, A, B, C, f4, K4, expand( eData, 77 ) );
subRound( C, D, E, A, B, f4, K4, expand( eData, 78 ) );
subRound( B, C, D, E, A, f4, K4, expand( eData, 79 ) );
/* Build message digest */
digest[ 0 ] += A;
digest[ 1 ] += B;
digest[ 2 ] += C;
digest[ 3 ] += D;
digest[ 4 ] += E;
}
#else
#define HASH_BUFFER_SIZE 4
#define HASH_TRANSFORM MD5Transform
/*
* MD5 transform algorithm, taken from code written by Colin Plumb,
* and put into the public domain
*
* QUESTION: Replace this with SHA, which as generally received better
* reviews from the cryptographic community?
*/
/* The four core functions - F1 is optimized somewhat */
/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))
/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
( w += f(x, y, z) + data, w = w<<s | w>>(32-s), w += x )
/*
* The core of the MD5 algorithm, this alters an existing MD5 hash to
* reflect the addition of 16 longwords of new data. MD5Update blocks
* the data and converts bytes into longwords for this routine.
*/
static void MD5Transform(__u32 buf[4],
__u32 const in[16])
{
__u32 a, b, c, d;
a = buf[0];
b = buf[1];
c = buf[2];
d = buf[3];
MD5STEP(F1, a, b, c, d, in[ 0]+0xd76aa478, 7);
MD5STEP(F1, d, a, b, c, in[ 1]+0xe8c7b756, 12);
MD5STEP(F1, c, d, a, b, in[ 2]+0x242070db, 17);
MD5STEP(F1, b, c, d, a, in[ 3]+0xc1bdceee, 22);
MD5STEP(F1, a, b, c, d, in[ 4]+0xf57c0faf, 7);
MD5STEP(F1, d, a, b, c, in[ 5]+0x4787c62a, 12);
MD5STEP(F1, c, d, a, b, in[ 6]+0xa8304613, 17);
MD5STEP(F1, b, c, d, a, in[ 7]+0xfd469501, 22);
MD5STEP(F1, a, b, c, d, in[ 8]+0x698098d8, 7);
MD5STEP(F1, d, a, b, c, in[ 9]+0x8b44f7af, 12);
MD5STEP(F1, c, d, a, b, in[10]+0xffff5bb1, 17);
MD5STEP(F1, b, c, d, a, in[11]+0x895cd7be, 22);
MD5STEP(F1, a, b, c, d, in[12]+0x6b901122, 7);
MD5STEP(F1, d, a, b, c, in[13]+0xfd987193, 12);
MD5STEP(F1, c, d, a, b, in[14]+0xa679438e, 17);
MD5STEP(F1, b, c, d, a, in[15]+0x49b40821, 22);
MD5STEP(F2, a, b, c, d, in[ 1]+0xf61e2562, 5);
MD5STEP(F2, d, a, b, c, in[ 6]+0xc040b340, 9);
MD5STEP(F2, c, d, a, b, in[11]+0x265e5a51, 14);
MD5STEP(F2, b, c, d, a, in[ 0]+0xe9b6c7aa, 20);
MD5STEP(F2, a, b, c, d, in[ 5]+0xd62f105d, 5);
MD5STEP(F2, d, a, b, c, in[10]+0x02441453, 9);
MD5STEP(F2, c, d, a, b, in[15]+0xd8a1e681, 14);
MD5STEP(F2, b, c, d, a, in[ 4]+0xe7d3fbc8, 20);
MD5STEP(F2, a, b, c, d, in[ 9]+0x21e1cde6, 5);
MD5STEP(F2, d, a, b, c, in[14]+0xc33707d6, 9);
MD5STEP(F2, c, d, a, b, in[ 3]+0xf4d50d87, 14);
MD5STEP(F2, b, c, d, a, in[ 8]+0x455a14ed, 20);
MD5STEP(F2, a, b, c, d, in[13]+0xa9e3e905, 5);
MD5STEP(F2, d, a, b, c, in[ 2]+0xfcefa3f8, 9);
MD5STEP(F2, c, d, a, b, in[ 7]+0x676f02d9, 14);
MD5STEP(F2, b, c, d, a, in[12]+0x8d2a4c8a, 20);
MD5STEP(F3, a, b, c, d, in[ 5]+0xfffa3942, 4);
MD5STEP(F3, d, a, b, c, in[ 8]+0x8771f681, 11);
MD5STEP(F3, c, d, a, b, in[11]+0x6d9d6122, 16);
MD5STEP(F3, b, c, d, a, in[14]+0xfde5380c, 23);
MD5STEP(F3, a, b, c, d, in[ 1]+0xa4beea44, 4);
MD5STEP(F3, d, a, b, c, in[ 4]+0x4bdecfa9, 11);
MD5STEP(F3, c, d, a, b, in[ 7]+0xf6bb4b60, 16);
MD5STEP(F3, b, c, d, a, in[10]+0xbebfbc70, 23);
MD5STEP(F3, a, b, c, d, in[13]+0x289b7ec6, 4);
MD5STEP(F3, d, a, b, c, in[ 0]+0xeaa127fa, 11);
MD5STEP(F3, c, d, a, b, in[ 3]+0xd4ef3085, 16);
MD5STEP(F3, b, c, d, a, in[ 6]+0x04881d05, 23);
MD5STEP(F3, a, b, c, d, in[ 9]+0xd9d4d039, 4);
MD5STEP(F3, d, a, b, c, in[12]+0xe6db99e5, 11);
MD5STEP(F3, c, d, a, b, in[15]+0x1fa27cf8, 16);
MD5STEP(F3, b, c, d, a, in[ 2]+0xc4ac5665, 23);
MD5STEP(F4, a, b, c, d, in[ 0]+0xf4292244, 6);
MD5STEP(F4, d, a, b, c, in[ 7]+0x432aff97, 10);
MD5STEP(F4, c, d, a, b, in[14]+0xab9423a7, 15);
MD5STEP(F4, b, c, d, a, in[ 5]+0xfc93a039, 21);
MD5STEP(F4, a, b, c, d, in[12]+0x655b59c3, 6);
MD5STEP(F4, d, a, b, c, in[ 3]+0x8f0ccc92, 10);
MD5STEP(F4, c, d, a, b, in[10]+0xffeff47d, 15);
MD5STEP(F4, b, c, d, a, in[ 1]+0x85845dd1, 21);
MD5STEP(F4, a, b, c, d, in[ 8]+0x6fa87e4f, 6);
MD5STEP(F4, d, a, b, c, in[15]+0xfe2ce6e0, 10);
MD5STEP(F4, c, d, a, b, in[ 6]+0xa3014314, 15);
MD5STEP(F4, b, c, d, a, in[13]+0x4e0811a1, 21);
MD5STEP(F4, a, b, c, d, in[ 4]+0xf7537e82, 6);
MD5STEP(F4, d, a, b, c, in[11]+0xbd3af235, 10);
MD5STEP(F4, c, d, a, b, in[ 2]+0x2ad7d2bb, 15);
MD5STEP(F4, b, c, d, a, in[ 9]+0xeb86d391, 21);
buf[0] += a;
buf[1] += b;
buf[2] += c;
buf[3] += d;
}
#undef F1
#undef F2
#undef F3
#undef F4
#undef MD5STEP
#endif
#if POOLWORDS % 16
#error extract_entropy() assumes that POOLWORDS is a multiple of 16 words.
#endif
/*
* 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.
*/
static int extract_entropy(struct random_bucket *r, char * buf,
int nbytes, int to_user)
{
int ret, i;
__u32 tmp[HASH_BUFFER_SIZE];
char *cp,*dp;
if (to_user) {
ret = verify_area(VERIFY_WRITE, (void *) buf, nbytes);
if (ret)
return(ret);
}
add_timer_randomness(r, &extract_timer_state, nbytes);
/* Redundant, but just in case... */
if (r->entropy_count > POOLBITS)
r->entropy_count = POOLBITS;
ret = nbytes;
if (r->entropy_count / 8 >= nbytes)
r->entropy_count -= nbytes*8;
else
r->entropy_count = 0;
while (nbytes) {
/* Hash the pool to get the output */
tmp[0] = 0x67452301;
tmp[1] = 0xefcdab89;
tmp[2] = 0x98badcfe;
tmp[3] = 0x10325476;
#ifdef USE_SHA
tmp[4] = 0xc3d2e1f0;
#endif
for (i = 0; i < POOLWORDS; i += 16)
HASH_TRANSFORM(tmp, r->pool+i);
/* Modify pool so next hash will produce different results */
add_entropy_word(r, tmp[0]);
add_entropy_word(r, tmp[1]);
add_entropy_word(r, tmp[2]);
add_entropy_word(r, tmp[3]);
#ifdef USE_SHA
add_entropy_word(r, tmp[4]);
#endif
/*
* Run the hash transform one more time, since we want
* to add at least minimal obscuring of the inputs to
* add_entropy_word().
*/
HASH_TRANSFORM(tmp, r->pool);
/*
* In case the hash function has some recognizable
* output pattern, we fold it in half.
*/
cp = (char *) tmp;
dp = cp + (HASH_BUFFER_SIZE*sizeof(__u32)) - 1;
for (i=0; i < HASH_BUFFER_SIZE*sizeof(__u32)/2; i++) {
*cp ^= *dp;
cp++; dp--;
}
/* Copy data to destination buffer */
i = MIN(nbytes, HASH_BUFFER_SIZE*sizeof(__u32)/2);
if (to_user)
memcpy_tofs(buf, (__u8 const *)tmp, i);
else
memcpy(buf, (__u8 const *)tmp, i);
nbytes -= i;
buf += i;
add_timer_randomness(r, &extract_timer_state, nbytes);
if (to_user && need_resched)
schedule();
}
/* Wipe data 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(&random_state, (char *) buf, nbytes, 0);
}
static int
random_read(struct inode * inode, struct file * file, char * buf, int nbytes)
{
struct wait_queue wait = { current, NULL };
int n;
int retval = 0;
int count = 0;
if (nbytes == 0)
return 0;
add_wait_queue(&random_wait, &wait);
while (nbytes > 0) {
current->state = TASK_INTERRUPTIBLE;
n = nbytes;
if (n > random_state.entropy_count / 8)
n = random_state.entropy_count / 8;
if (n == 0) {
if (file->f_flags & O_NONBLOCK) {
retval = -EAGAIN;
break;
}
if (current->signal & ~current->blocked) {
retval = -ERESTARTSYS;
break;
}
schedule();
continue;
}
n = extract_entropy(&random_state, buf, n, 1);
if (n < 0) {
if (count == 0)
retval = n;
break;
}
count += n;
buf += n;
nbytes -= n;
break; /* This break makes the device work */
/* like a named pipe */
}
current->state = TASK_RUNNING;
remove_wait_queue(&random_wait, &wait);
/*
* If we gave the user some bytes and we have an inode pointer,
* update the access time.
*/
if (inode && count != 0)
UPDATE_ATIME(inode);
return (count ? count : retval);
}
static int
random_read_unlimited(struct inode * inode, struct file * file,
char * buf, int nbytes)
{
return extract_entropy(&random_state, buf, nbytes, 1);
}
static int
random_select(struct inode *inode, struct file *file,
int sel_type, select_table * wait)
{
switch (sel_type) {
case SEL_IN:
if (random_state.entropy_count >= 8)
return 1;
select_wait(&random_wait, wait);
break;
case SEL_OUT:
if (random_state.entropy_count < WAIT_OUTPUT_BITS)
return 1;
select_wait(&random_wait, wait);
break;
}
return 0;
}
static int
random_write(struct inode * inode, struct file * file,
const char * buffer, int count)
{
int i;
__u32 word, *p;
if (count < 0)
return -EINVAL;
i = verify_area(VERIFY_READ, (void *) buffer, count);
if (i)
return i;
for (i = count, p = (__u32 *)buffer;
i >= sizeof(__u32);
i-= sizeof(__u32), p++) {
memcpy_fromfs(&word, p, sizeof(__u32));
add_entropy_word(&random_state, word);
}
if (i) {
word = 0;
memcpy_fromfs(&word, p, i);
add_entropy_word(&random_state, word);
}
if (inode) {
inode->i_mtime = CURRENT_TIME;
inode->i_dirt = 1;
}
return count;
}
static int
random_ioctl(struct inode * inode, struct file * file,
unsigned int cmd, unsigned long arg)
{
int *p, size, ent_count;
int retval;
/*
* Translate old 1.3.XX values.
* Remove this code in 2.1.0.
* <mec@duracef.shout.net>
*/
switch (cmd) {
case 0x01080000: cmd = RNDGETENTCNT; break;
case 0x01080001: cmd = RNDADDTOENTCNT; break;
case 0x01080002: cmd = RNDGETPOOL; break;
case 0x01080003: cmd = RNDADDENTROPY; break;
case 0x01080004: cmd = RNDZAPENTCNT; break;
case 0x01080006: cmd = RNDCLEARPOOL; break;
}
switch (cmd) {
case RNDGETENTCNT:
retval = verify_area(VERIFY_WRITE, (void *) arg, sizeof(int));
if (retval)
return(retval);
ent_count = random_state.entropy_count;
put_user(ent_count, (int *) arg);
return 0;
case RNDADDTOENTCNT:
if (!suser())
return -EPERM;
retval = verify_area(VERIFY_READ, (void *) arg, sizeof(int));
if (retval)
return(retval);
ent_count = get_user((int *) arg);
/*
* Add i to entropy_count, limiting the result to be
* between 0 and POOLBITS.
*/
if (ent_count < -random_state.entropy_count)
random_state.entropy_count = 0;
else if (ent_count > POOLBITS)
random_state.entropy_count = POOLBITS;
else {
random_state.entropy_count += ent_count;
if (random_state.entropy_count > POOLBITS)
random_state.entropy_count = POOLBITS;
if (random_state.entropy_count < 0)
random_state.entropy_count = 0;
}
/*
* Wake up waiting processes if we have enough
* entropy.
*/
if (random_state.entropy_count >= WAIT_INPUT_BITS)
wake_up_interruptible(&random_wait);
return 0;
case RNDGETPOOL:
if (!suser())
return -EPERM;
p = (int *) arg;
retval = verify_area(VERIFY_WRITE, (void *) p, sizeof(int));
if (retval)
return(retval);
ent_count = random_state.entropy_count;
put_user(ent_count, p++);
retval = verify_area(VERIFY_WRITE, (void *) p, sizeof(int));
if (retval)
return(retval);
size = get_user(p);
put_user(POOLWORDS, p++);
if (size < 0)
return -EINVAL;
if (size > POOLWORDS)
size = POOLWORDS;
retval = verify_area(VERIFY_WRITE, (void *) p,
size * sizeof(__u32));
if (retval)
return retval;
memcpy_tofs(p, random_state.pool, size*sizeof(__u32));
return 0;
case RNDADDENTROPY:
if (!suser())
return -EPERM;
p = (int *) arg;
retval = verify_area(VERIFY_READ, (void *) p, 2*sizeof(int));
if (retval)
return(retval);
ent_count = get_user(p++);
if (ent_count < 0)
return -EINVAL;
size = get_user(p++);
retval = random_write(0, file, (const char *) p, size);
if (retval < 0)
return retval;
/*
* Add ent_count to entropy_count, limiting the result to be
* between 0 and POOLBITS.
*/
if (ent_count > POOLBITS)
random_state.entropy_count = POOLBITS;
else {
random_state.entropy_count += ent_count;
if (random_state.entropy_count > POOLBITS)
random_state.entropy_count = POOLBITS;
if (random_state.entropy_count < 0)
random_state.entropy_count = 0;
}
/*
* Wake up waiting processes if we have enough
* entropy.
*/
if (random_state.entropy_count >= WAIT_INPUT_BITS)
wake_up_interruptible(&random_wait);
return 0;
case RNDZAPENTCNT:
if (!suser())
return -EPERM;
random_state.entropy_count = 0;
return 0;
case RNDCLEARPOOL:
/* Clear the entropy pool and associated counters. */
if (!suser())
return -EPERM;
rand_clear_pool();
return 0;
default:
return -EINVAL;
}
}
struct file_operations random_fops = {
NULL, /* random_lseek */
random_read,
random_write,
NULL, /* random_readdir */
random_select, /* random_select */
random_ioctl,
NULL, /* random_mmap */
NULL, /* no special open code */
NULL /* no special release code */
};
struct file_operations urandom_fops = {
NULL, /* unrandom_lseek */
random_read_unlimited,
random_write,
NULL, /* urandom_readdir */
NULL, /* urandom_select */
random_ioctl,
NULL, /* urandom_mmap */
NULL, /* no special open code */
NULL /* no special release code */
};
/*
* 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.
*/
__u32 secure_tcp_sequence_number(__u32 saddr, __u32 daddr,
__u16 sport, __u16 dport)
{
static int is_init = 0;
static __u32 secret[16];
struct timeval tv;
__u32 tmp[16];
__u32 seq;
/*
* Pick a random secret the first time we open a TCP
* connection.
*/
if (is_init == 0) {
get_random_bytes(&secret, sizeof(secret));
is_init = 1;
}
memcpy(tmp, secret, sizeof(tmp));
/*
* Pick a unique starting offset for each
* TCP connection endpoints (saddr, daddr, sport, dport)
*/
tmp[8]=saddr;
tmp[9]=daddr;
tmp[10]=(sport << 16) + dport;
HASH_TRANSFORM(tmp, tmp);
/*
* As close as possible to RFC 793, which
* suggests using a 250kHz clock.
* Further reading shows this assumes 2MB/s networks.
* For 10MB/s ethernet, a 1MHz clock is appropriate.
* That's funny, Linux has one built in! Use it!
*/
do_gettimeofday(&tv);
seq = tmp[1] + tv.tv_usec+tv.tv_sec*1000000;
#if 0
/*
ugh...we can only use in_ntoa once per printk, splitting
a single line of info into multiple printk's confuses klogd,
and Linus says in_ntoa sucks anyway :)
*/
printk("init_seq(%d.%d.%d.%d:%d, %d.%d.%d.%d:%d) = %d\n",
NIPQUAD(saddr), sport, NIPQUAD(daddr), dport, seq);
#endif
return (seq);
}
#ifdef CONFIG_RST_COOKIES
/*
* TCP security probe sequence number picking. Losely based upon
* secure sequence number algorithm above.
*/
__u32 secure_tcp_probe_number(__u32 saddr, __u32 daddr,
__u16 sport, __u16 dport, __u32 sseq, int validate)
{
static int is_init = 0;
static int valid_secret[2];
static __u32 secret_timestamp[2];
static __u32 secret[2][16];
static int offset = 0;
__u32 tmp[16];
__u32 seq;
/*
* Pick a random secret the first time we open a TCP
* connection, and expire secrets older than 5 minutes.
*/
if (is_init == 0 || jiffies-secret_timestamp[offset] > 600*HZ) {
if (is_init == 0) valid_secret[0] = valid_secret[1] = 0;
else offset = (offset+1)%2;
get_random_bytes(&secret[offset], sizeof(secret[offset]));
valid_secret[offset] = 1;
secret_timestamp[offset] = jiffies;
is_init = 1;
}
memcpy(tmp, secret[offset], sizeof(tmp));
/*
* Pick a unique starting offset for each
* TCP connection endpoints (saddr, daddr, sport, dport)
*/
tmp[8]=saddr;
tmp[9]=daddr;
tmp[10]=(sport << 16) + dport;
HASH_TRANSFORM(tmp, tmp);
seq = tmp[1];
if (!validate) {
if (seq == sseq) seq++;
#if 0
printk("init_seq(%d.%d.%d.%d:%d %d.%d.%d.%d:%d, %d) = %d\n",
NIPQUAD(saddr), sport, NIPQUAD(daddr), dport, sseq, seq);
#endif
return (seq);
} else {
if (seq == sseq || (seq+1) == sseq) {
printk("validated probe(%d.%d.%d.%d:%d, %d.%d.%d.%d:%d, %d)\n",
NIPQUAD(saddr), sport, NIPQUAD(daddr), dport, sseq);
return 1;
}
if (jiffies-secret_timestamp[(offset+1)%2] <= 1200*HZ) {
memcpy(tmp, secret[(offset+1)%2], sizeof(tmp));
tmp[8]=saddr;
tmp[9]=daddr;
tmp[10]=(sport << 16) + dport;
HASH_TRANSFORM(tmp, tmp);
seq = tmp[1];
if (seq == sseq || (seq+1) == sseq) {
#ifdef 0
printk("validated probe(%d.%d.%d.%d:%d, %d.%d.%d.%d:%d, %d)\n",
NIPQUAD(saddr), sport, NIPQUAD(daddr), dport, sseq);
#endif
return 1;
}
}
#ifdef 0
printk("failed validation on probe(%d.%d.%d.%d:%d, %d.%d.%d.%d:%d, %d)\n",
NIPQUAD(saddr), sport, NIPQUAD(daddr), dport, sseq);
#endif
return 0;
}
}
#endif
#ifdef CONFIG_SYN_COOKIES
/*
* Secure SYN cookie computation. This is the algorithm worked out by
* Dan Bernstien 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;
*
*/
__u32 secure_tcp_syn_cookie(__u32 saddr, __u32 daddr,
__u16 sport, __u16 dport, __u32 sseq, __u32 count)
{
static int is_init = 0;
static __u32 secret[2][16];
__u32 tmp[16];
__u32 seq;
/*
* Pick two random secret the first time we open a TCP connection.
*/
if (is_init == 0) {
get_random_bytes(&secret[0], sizeof(secret[0]));
get_random_bytes(&secret[1], sizeof(secret[1]));
is_init = 1;
}
/*
* Compute the secure sequence number.
* The output should be:
* MD5(sec1,saddr,sport,daddr,dport,sec1) + their sequence number
* + (count * 2^24)
* + (MD5(sec2,saddr,sport,daddr,dport,count,sec2) % 2^24).
* Where count increases every minute by 1.
*/
memcpy(tmp, secret[0], sizeof(tmp));
tmp[8]=saddr;
tmp[9]=daddr;
tmp[10]=(sport << 16) + dport;
HASH_TRANSFORM(tmp, tmp);
seq = tmp[1];
memcpy(tmp, secret[1], sizeof(tmp));
tmp[8]=saddr;
tmp[9]=daddr;
tmp[10]=(sport << 16) + dport;
tmp[11]=count; /* minute counter */
HASH_TRANSFORM(tmp, tmp);
seq += sseq + (count << 24) + (tmp[1] & 0x00ffffff);
/* Zap lower 3 bits to leave room for the MSS representation */
return (seq & 0xfffff8);
}
#endif
#ifdef RANDOM_BENCHMARK
/*
* This is so we can do some benchmarking of the random driver, to see
* how much overhead add_timer_randomness really takes. This only
* works on a Pentium, since it depends on the timer clock...
*
* Note: the results of this benchmark as of this writing (5/27/96)
*
* On a Pentium, add_timer_randomness() takes between 150 and 1000
* clock cycles, with an average of around 600 clock cycles. On a 75
* MHz Pentium, this translates to 2 to 13 microseconds, with an
* average time of 8 microseconds. This should be fast enough so we
* can use add_timer_randomness() even with the fastest of interrupts...
*/
static inline unsigned long long get_clock_cnt(void)
{
unsigned long low, high;
__asm__(".byte 0x0f,0x31" :"=a" (low), "=d" (high));
return (((unsigned long long) high << 31) | low);
}
static void initialize_benchmark(struct random_benchmark *bench,
const char *descr, int unit)
{
bench->times = 0;
bench->accum = 0;
bench->max = 0;
bench->min = 1 << 31;
bench->descr = descr;
bench->unit = unit;
}
static void begin_benchmark(struct random_benchmark *bench)
{
#ifdef BENCHMARK_NOINT
save_flags(bench->flags); cli();
#endif
bench->start_time = get_clock_cnt();
}
static void end_benchmark(struct random_benchmark *bench)
{
unsigned long ticks;
ticks = (unsigned long) (get_clock_cnt() - bench->start_time);
#ifdef BENCHMARK_NOINT
restore_flags(bench->flags);
#endif
if (ticks < bench->min)
bench->min = ticks;
if (ticks > bench->max)
bench->max = ticks;
bench->accum += ticks;
bench->times++;
if (bench->times == BENCHMARK_INTERVAL) {
printk("Random benchmark: %s %d: %lu min, %lu avg, "
"%lu max\n", bench->descr, bench->unit, bench->min,
bench->accum / BENCHMARK_INTERVAL, bench->max);
bench->times = 0;
bench->accum = 0;
bench->max = 0;
bench->min = 1 << 31;
}
}
#endif /* RANDOM_BENCHMARK */
