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/* * 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/config.h> /* CONFIG_RST_COOKIES and CONFIG_SYN_COOKIES */ #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) { if(current->signal & ~current->blocked) { if(nbytes==0) ret = -ERESTARTSYS; else ret -= nbytes; break; } 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 << 32) | 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 */