| /* |
| * random.c -- A strong random number generator |
| * |
| * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005 |
| * |
| * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All |
| * rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, and the entire permission notice in its entirety, |
| * including the disclaimer of warranties. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. The name of the author may not be used to endorse or promote |
| * products derived from this software without specific prior |
| * written permission. |
| * |
| * ALTERNATIVELY, this product may be distributed under the terms of |
| * the GNU General Public License, in which case the provisions of the GPL are |
| * required INSTEAD OF the above restrictions. (This clause is |
| * necessary due to a potential bad interaction between the GPL and |
| * the restrictions contained in a BSD-style copyright.) |
| * |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF |
| * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE |
| * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT |
| * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
| * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE |
| * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH |
| * DAMAGE. |
| */ |
| |
| /* |
| * (now, with legal B.S. out of the way.....) |
| * |
| * This routine gathers environmental noise from device drivers, etc., |
| * and returns good random numbers, suitable for cryptographic use. |
| * Besides the obvious cryptographic uses, these numbers are also good |
| * for seeding TCP sequence numbers, and other places where it is |
| * desirable to have numbers which are not only random, but hard to |
| * predict by an attacker. |
| * |
| * Theory of operation |
| * =================== |
| * |
| * Computers are very predictable devices. Hence it is extremely hard |
| * to produce truly random numbers on a computer --- as opposed to |
| * pseudo-random numbers, which can easily generated by using a |
| * algorithm. Unfortunately, it is very easy for attackers to guess |
| * the sequence of pseudo-random number generators, and for some |
| * applications this is not acceptable. So instead, we must try to |
| * gather "environmental noise" from the computer's environment, which |
| * must be hard for outside attackers to observe, and use that to |
| * generate random numbers. In a Unix environment, this is best done |
| * from inside the kernel. |
| * |
| * Sources of randomness from the environment include inter-keyboard |
| * timings, inter-interrupt timings from some interrupts, and other |
| * events which are both (a) non-deterministic and (b) hard for an |
| * outside observer to measure. Randomness from these sources are |
| * added to an "entropy pool", which is mixed using a CRC-like function. |
| * This is not cryptographically strong, but it is adequate assuming |
| * the randomness is not chosen maliciously, and it is fast enough that |
| * the overhead of doing it on every interrupt is very reasonable. |
| * As random bytes are mixed into the entropy pool, the routines keep |
| * an *estimate* of how many bits of randomness have been stored into |
| * the random number generator's internal state. |
| * |
| * When random bytes are desired, they are obtained by taking the SHA |
| * hash of the contents of the "entropy pool". The SHA hash avoids |
| * exposing the internal state of the entropy pool. It is believed to |
| * be computationally infeasible to derive any useful information |
| * about the input of SHA from its output. Even if it is possible to |
| * analyze SHA in some clever way, as long as the amount of data |
| * returned from the generator is less than the inherent entropy in |
| * the pool, the output data is totally unpredictable. For this |
| * reason, the routine decreases its internal estimate of how many |
| * bits of "true randomness" are contained in the entropy pool as it |
| * outputs random numbers. |
| * |
| * If this estimate goes to zero, the routine can still generate |
| * random numbers; however, an attacker may (at least in theory) be |
| * able to infer the future output of the generator from prior |
| * outputs. This requires successful cryptanalysis of SHA, which is |
| * not believed to be feasible, but there is a remote possibility. |
| * Nonetheless, these numbers should be useful for the vast majority |
| * of purposes. |
| * |
| * Exported interfaces ---- output |
| * =============================== |
| * |
| * There are three exported interfaces; the first is one designed to |
| * be used from within the kernel: |
| * |
| * void get_random_bytes(void *buf, int nbytes); |
| * |
| * This interface will return the requested number of random bytes, |
| * and place it in the requested buffer. |
| * |
| * The two other interfaces are two character devices /dev/random and |
| * /dev/urandom. /dev/random is suitable for use when very high |
| * quality randomness is desired (for example, for key generation or |
| * one-time pads), as it will only return a maximum of the number of |
| * bits of randomness (as estimated by the random number generator) |
| * contained in the entropy pool. |
| * |
| * The /dev/urandom device does not have this limit, and will return |
| * as many bytes as are requested. As more and more random bytes are |
| * requested without giving time for the entropy pool to recharge, |
| * this will result in random numbers that are merely cryptographically |
| * strong. For many applications, however, this is acceptable. |
| * |
| * Exported interfaces ---- input |
| * ============================== |
| * |
| * The current exported interfaces for gathering environmental noise |
| * from the devices are: |
| * |
| * void add_input_randomness(unsigned int type, unsigned int code, |
| * unsigned int value); |
| * void add_interrupt_randomness(int irq); |
| * |
| * add_input_randomness() uses the input layer interrupt timing, as well as |
| * the event type information from the hardware. |
| * |
| * add_interrupt_randomness() uses the inter-interrupt timing as random |
| * inputs to the entropy pool. Note that not all interrupts are good |
| * sources of randomness! For example, the timer interrupts is not a |
| * good choice, because the periodicity of the interrupts is too |
| * regular, and hence predictable to an attacker. Disk interrupts are |
| * a better measure, since the timing of the disk interrupts are more |
| * unpredictable. |
| * |
| * All of these routines try to estimate how many bits of randomness a |
| * particular randomness source. They do this by keeping track of the |
| * first and second order deltas of the event timings. |
| * |
| * Ensuring unpredictability at system startup |
| * ============================================ |
| * |
| * When any operating system starts up, it will go through a sequence |
| * of actions that are fairly predictable by an adversary, especially |
| * if the start-up does not involve interaction with a human operator. |
| * This reduces the actual number of bits of unpredictability in the |
| * entropy pool below the value in entropy_count. In order to |
| * counteract this effect, it helps to carry information in the |
| * entropy pool across shut-downs and start-ups. To do this, put the |
| * following lines an appropriate script which is run during the boot |
| * sequence: |
| * |
| * echo "Initializing random number generator..." |
| * random_seed=/var/run/random-seed |
| * # Carry a random seed from start-up to start-up |
| * # Load and then save the whole entropy pool |
| * if [ -f $random_seed ]; then |
| * cat $random_seed >/dev/urandom |
| * else |
| * touch $random_seed |
| * fi |
| * chmod 600 $random_seed |
| * dd if=/dev/urandom of=$random_seed count=1 bs=512 |
| * |
| * and the following lines in an appropriate script which is run as |
| * the system is shutdown: |
| * |
| * # Carry a random seed from shut-down to start-up |
| * # Save the whole entropy pool |
| * echo "Saving random seed..." |
| * random_seed=/var/run/random-seed |
| * touch $random_seed |
| * chmod 600 $random_seed |
| * dd if=/dev/urandom of=$random_seed count=1 bs=512 |
| * |
| * For example, on most modern systems using the System V init |
| * scripts, such code fragments would be found in |
| * /etc/rc.d/init.d/random. On older Linux systems, the correct script |
| * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0. |
| * |
| * Effectively, these commands cause the contents of the entropy pool |
| * to be saved at shut-down time and reloaded into the entropy pool at |
| * start-up. (The 'dd' in the addition to the bootup script is to |
| * make sure that /etc/random-seed is different for every start-up, |
| * even if the system crashes without executing rc.0.) Even with |
| * complete knowledge of the start-up activities, predicting the state |
| * of the entropy pool requires knowledge of the previous history of |
| * the system. |
| * |
| * Configuring the /dev/random driver under Linux |
| * ============================================== |
| * |
| * The /dev/random driver under Linux uses minor numbers 8 and 9 of |
| * the /dev/mem major number (#1). So if your system does not have |
| * /dev/random and /dev/urandom created already, they can be created |
| * by using the commands: |
| * |
| * mknod /dev/random c 1 8 |
| * mknod /dev/urandom c 1 9 |
| * |
| * Acknowledgements: |
| * ================= |
| * |
| * Ideas for constructing this random number generator were derived |
| * from Pretty Good Privacy's random number generator, and from private |
| * discussions with Phil Karn. Colin Plumb provided a faster random |
| * number generator, which speed up the mixing function of the entropy |
| * pool, taken from PGPfone. Dale Worley has also contributed many |
| * useful ideas and suggestions to improve this driver. |
| * |
| * Any flaws in the design are solely my responsibility, and should |
| * not be attributed to the Phil, Colin, or any of authors of PGP. |
| * |
| * Further background information on this topic may be obtained from |
| * RFC 1750, "Randomness Recommendations for Security", by Donald |
| * Eastlake, Steve Crocker, and Jeff Schiller. |
| */ |
| |
| #include <linux/utsname.h> |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/major.h> |
| #include <linux/string.h> |
| #include <linux/fcntl.h> |
| #include <linux/slab.h> |
| #include <linux/random.h> |
| #include <linux/poll.h> |
| #include <linux/init.h> |
| #include <linux/fs.h> |
| #include <linux/genhd.h> |
| #include <linux/interrupt.h> |
| #include <linux/spinlock.h> |
| #include <linux/percpu.h> |
| #include <linux/cryptohash.h> |
| |
| #include <asm/processor.h> |
| #include <asm/uaccess.h> |
| #include <asm/irq.h> |
| #include <asm/io.h> |
| |
| /* |
| * Configuration information |
| */ |
| #define INPUT_POOL_WORDS 128 |
| #define OUTPUT_POOL_WORDS 32 |
| #define SEC_XFER_SIZE 512 |
| |
| /* |
| * The minimum number of bits of entropy before we wake up a read on |
| * /dev/random. Should be enough to do a significant reseed. |
| */ |
| static int random_read_wakeup_thresh = 64; |
| |
| /* |
| * If the entropy count falls under this number of bits, then we |
| * should wake up processes which are selecting or polling on write |
| * access to /dev/random. |
| */ |
| static int random_write_wakeup_thresh = 128; |
| |
| /* |
| * When the input pool goes over trickle_thresh, start dropping most |
| * samples to avoid wasting CPU time and reduce lock contention. |
| */ |
| |
| static int trickle_thresh __read_mostly = INPUT_POOL_WORDS * 28; |
| |
| static DEFINE_PER_CPU(int, trickle_count) = 0; |
| |
| /* |
| * A pool of size .poolwords is stirred with a primitive polynomial |
| * of degree .poolwords over GF(2). The taps for various sizes are |
| * defined below. They are chosen to be evenly spaced (minimum RMS |
| * distance from evenly spaced; the numbers in the comments are a |
| * scaled squared error sum) except for the last tap, which is 1 to |
| * get the twisting happening as fast as possible. |
| */ |
| static struct poolinfo { |
| int poolwords; |
| int tap1, tap2, tap3, tap4, tap5; |
| } poolinfo_table[] = { |
| /* x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 -- 105 */ |
| { 128, 103, 76, 51, 25, 1 }, |
| /* x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 -- 15 */ |
| { 32, 26, 20, 14, 7, 1 }, |
| #if 0 |
| /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */ |
| { 2048, 1638, 1231, 819, 411, 1 }, |
| |
| /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */ |
| { 1024, 817, 615, 412, 204, 1 }, |
| |
| /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */ |
| { 1024, 819, 616, 410, 207, 2 }, |
| |
| /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */ |
| { 512, 411, 308, 208, 104, 1 }, |
| |
| /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */ |
| { 512, 409, 307, 206, 102, 2 }, |
| /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */ |
| { 512, 409, 309, 205, 103, 2 }, |
| |
| /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */ |
| { 256, 205, 155, 101, 52, 1 }, |
| |
| /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */ |
| { 128, 103, 78, 51, 27, 2 }, |
| |
| /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */ |
| { 64, 52, 39, 26, 14, 1 }, |
| #endif |
| }; |
| |
| #define POOLBITS poolwords*32 |
| #define POOLBYTES poolwords*4 |
| |
| /* |
| * For the purposes of better mixing, we use the CRC-32 polynomial as |
| * well to make a twisted Generalized Feedback Shift Reigster |
| * |
| * (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR generators. ACM |
| * Transactions on Modeling and Computer Simulation 2(3):179-194. |
| * Also see M. Matsumoto & Y. Kurita, 1994. Twisted GFSR generators |
| * II. ACM Transactions on Mdeling and Computer Simulation 4:254-266) |
| * |
| * Thanks to Colin Plumb for suggesting this. |
| * |
| * We have not analyzed the resultant polynomial to prove it primitive; |
| * in fact it almost certainly isn't. Nonetheless, the irreducible factors |
| * of a random large-degree polynomial over GF(2) are more than large enough |
| * that periodicity is not a concern. |
| * |
| * The input hash is much less sensitive than the output hash. All |
| * that we want of it is that it be a good non-cryptographic hash; |
| * i.e. it not produce collisions when fed "random" data of the sort |
| * we expect to see. As long as the pool state differs for different |
| * inputs, we have preserved the input entropy and done a good job. |
| * The fact that an intelligent attacker can construct inputs that |
| * will produce controlled alterations to the pool's state is not |
| * important because we don't consider such inputs to contribute any |
| * randomness. The only property we need with respect to them is that |
| * the attacker can't increase his/her knowledge of the pool's state. |
| * Since all additions are reversible (knowing the final state and the |
| * input, you can reconstruct the initial state), if an attacker has |
| * any uncertainty about the initial state, he/she can only shuffle |
| * that uncertainty about, but never cause any collisions (which would |
| * decrease the uncertainty). |
| * |
| * The chosen system lets the state of the pool be (essentially) the input |
| * modulo the generator polymnomial. Now, for random primitive polynomials, |
| * this is a universal class of hash functions, meaning that the chance |
| * of a collision is limited by the attacker's knowledge of the generator |
| * polynomail, so if it is chosen at random, an attacker can never force |
| * a collision. Here, we use a fixed polynomial, but we *can* assume that |
| * ###--> it is unknown to the processes generating the input entropy. <-### |
| * Because of this important property, this is a good, collision-resistant |
| * hash; hash collisions will occur no more often than chance. |
| */ |
| |
| /* |
| * Static global variables |
| */ |
| static DECLARE_WAIT_QUEUE_HEAD(random_read_wait); |
| static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); |
| |
| #if 0 |
| static int debug = 0; |
| module_param(debug, bool, 0644); |
| #define DEBUG_ENT(fmt, arg...) do { if (debug) \ |
| printk(KERN_DEBUG "random %04d %04d %04d: " \ |
| fmt,\ |
| input_pool.entropy_count,\ |
| blocking_pool.entropy_count,\ |
| nonblocking_pool.entropy_count,\ |
| ## arg); } while (0) |
| #else |
| #define DEBUG_ENT(fmt, arg...) do {} while (0) |
| #endif |
| |
| /********************************************************************** |
| * |
| * OS independent entropy store. Here are the functions which handle |
| * storing entropy in an entropy pool. |
| * |
| **********************************************************************/ |
| |
| struct entropy_store; |
| struct entropy_store { |
| /* mostly-read data: */ |
| struct poolinfo *poolinfo; |
| __u32 *pool; |
| const char *name; |
| int limit; |
| struct entropy_store *pull; |
| |
| /* read-write data: */ |
| spinlock_t lock ____cacheline_aligned_in_smp; |
| unsigned add_ptr; |
| int entropy_count; |
| int input_rotate; |
| }; |
| |
| static __u32 input_pool_data[INPUT_POOL_WORDS]; |
| static __u32 blocking_pool_data[OUTPUT_POOL_WORDS]; |
| static __u32 nonblocking_pool_data[OUTPUT_POOL_WORDS]; |
| |
| static struct entropy_store input_pool = { |
| .poolinfo = &poolinfo_table[0], |
| .name = "input", |
| .limit = 1, |
| .lock = __SPIN_LOCK_UNLOCKED(&input_pool.lock), |
| .pool = input_pool_data |
| }; |
| |
| static struct entropy_store blocking_pool = { |
| .poolinfo = &poolinfo_table[1], |
| .name = "blocking", |
| .limit = 1, |
| .pull = &input_pool, |
| .lock = __SPIN_LOCK_UNLOCKED(&blocking_pool.lock), |
| .pool = blocking_pool_data |
| }; |
| |
| static struct entropy_store nonblocking_pool = { |
| .poolinfo = &poolinfo_table[1], |
| .name = "nonblocking", |
| .pull = &input_pool, |
| .lock = __SPIN_LOCK_UNLOCKED(&nonblocking_pool.lock), |
| .pool = nonblocking_pool_data |
| }; |
| |
| /* |
| * This function adds a byte into the entropy "pool". It does not |
| * update the entropy estimate. The caller should call |
| * credit_entropy_store if this is appropriate. |
| * |
| * The pool is stirred with a primitive polynomial of the appropriate |
| * degree, and then twisted. We twist by three bits at a time because |
| * it's cheap to do so and helps slightly in the expected case where |
| * the entropy is concentrated in the low-order bits. |
| */ |
| static void __add_entropy_words(struct entropy_store *r, const __u32 *in, |
| int nwords, __u32 out[16]) |
| { |
| static __u32 const twist_table[8] = { |
| 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158, |
| 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; |
| unsigned long i, add_ptr, tap1, tap2, tap3, tap4, tap5; |
| int new_rotate, input_rotate; |
| int wordmask = r->poolinfo->poolwords - 1; |
| __u32 w, next_w; |
| unsigned long flags; |
| |
| /* Taps are constant, so we can load them without holding r->lock. */ |
| tap1 = r->poolinfo->tap1; |
| tap2 = r->poolinfo->tap2; |
| tap3 = r->poolinfo->tap3; |
| tap4 = r->poolinfo->tap4; |
| tap5 = r->poolinfo->tap5; |
| next_w = *in++; |
| |
| spin_lock_irqsave(&r->lock, flags); |
| prefetch_range(r->pool, wordmask); |
| input_rotate = r->input_rotate; |
| add_ptr = r->add_ptr; |
| |
| while (nwords--) { |
| w = rol32(next_w, input_rotate); |
| if (nwords > 0) |
| next_w = *in++; |
| i = add_ptr = (add_ptr - 1) & wordmask; |
| /* |
| * Normally, we add 7 bits of rotation to the pool. |
| * At the beginning of the pool, add an extra 7 bits |
| * rotation, so that successive passes spread the |
| * input bits across the pool evenly. |
| */ |
| new_rotate = input_rotate + 14; |
| if (i) |
| new_rotate = input_rotate + 7; |
| input_rotate = new_rotate & 31; |
| |
| /* XOR in the various taps */ |
| w ^= r->pool[(i + tap1) & wordmask]; |
| w ^= r->pool[(i + tap2) & wordmask]; |
| w ^= r->pool[(i + tap3) & wordmask]; |
| w ^= r->pool[(i + tap4) & wordmask]; |
| w ^= r->pool[(i + tap5) & wordmask]; |
| w ^= r->pool[i]; |
| r->pool[i] = (w >> 3) ^ twist_table[w & 7]; |
| } |
| |
| r->input_rotate = input_rotate; |
| r->add_ptr = add_ptr; |
| |
| if (out) { |
| for (i = 0; i < 16; i++) { |
| out[i] = r->pool[add_ptr]; |
| add_ptr = (add_ptr - 1) & wordmask; |
| } |
| } |
| |
| spin_unlock_irqrestore(&r->lock, flags); |
| } |
| |
| static inline void add_entropy_words(struct entropy_store *r, const __u32 *in, |
| int nwords) |
| { |
| __add_entropy_words(r, in, nwords, NULL); |
| } |
| |
| /* |
| * Credit (or debit) the entropy store with n bits of entropy |
| */ |
| static void credit_entropy_store(struct entropy_store *r, int nbits) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(&r->lock, flags); |
| |
| if (r->entropy_count + nbits < 0) { |
| DEBUG_ENT("negative entropy/overflow (%d+%d)\n", |
| r->entropy_count, nbits); |
| r->entropy_count = 0; |
| } else if (r->entropy_count + nbits > r->poolinfo->POOLBITS) { |
| r->entropy_count = r->poolinfo->POOLBITS; |
| } else { |
| r->entropy_count += nbits; |
| if (nbits) |
| DEBUG_ENT("added %d entropy credits to %s\n", |
| nbits, r->name); |
| } |
| |
| spin_unlock_irqrestore(&r->lock, flags); |
| } |
| |
| /********************************************************************* |
| * |
| * Entropy input management |
| * |
| *********************************************************************/ |
| |
| /* There is one of these per entropy source */ |
| struct timer_rand_state { |
| cycles_t last_time; |
| long last_delta,last_delta2; |
| unsigned dont_count_entropy:1; |
| }; |
| |
| static struct timer_rand_state input_timer_state; |
| static struct timer_rand_state *irq_timer_state[NR_IRQS]; |
| |
| /* |
| * This function adds entropy to the entropy "pool" by using timing |
| * delays. It uses the timer_rand_state structure to make an estimate |
| * of how many bits of entropy this call has added to the pool. |
| * |
| * The number "num" is also added to the pool - it should somehow describe |
| * the type of event which just happened. This is currently 0-255 for |
| * keyboard scan codes, and 256 upwards for interrupts. |
| * |
| */ |
| static void add_timer_randomness(struct timer_rand_state *state, unsigned num) |
| { |
| struct { |
| cycles_t cycles; |
| long jiffies; |
| unsigned num; |
| } sample; |
| long delta, delta2, delta3; |
| |
| preempt_disable(); |
| /* if over the trickle threshold, use only 1 in 4096 samples */ |
| if (input_pool.entropy_count > trickle_thresh && |
| (__get_cpu_var(trickle_count)++ & 0xfff)) |
| goto out; |
| |
| sample.jiffies = jiffies; |
| sample.cycles = get_cycles(); |
| sample.num = num; |
| add_entropy_words(&input_pool, (u32 *)&sample, sizeof(sample)/4); |
| |
| /* |
| * Calculate number of bits of randomness we probably added. |
| * We take into account the first, second and third-order deltas |
| * in order to make our estimate. |
| */ |
| |
| if (!state->dont_count_entropy) { |
| delta = sample.jiffies - state->last_time; |
| state->last_time = sample.jiffies; |
| |
| delta2 = delta - state->last_delta; |
| state->last_delta = delta; |
| |
| delta3 = delta2 - state->last_delta2; |
| state->last_delta2 = delta2; |
| |
| if (delta < 0) |
| delta = -delta; |
| if (delta2 < 0) |
| delta2 = -delta2; |
| if (delta3 < 0) |
| delta3 = -delta3; |
| if (delta > delta2) |
| delta = delta2; |
| if (delta > delta3) |
| delta = delta3; |
| |
| /* |
| * delta is now minimum absolute delta. |
| * Round down by 1 bit on general principles, |
| * and limit entropy entimate to 12 bits. |
| */ |
| credit_entropy_store(&input_pool, |
| min_t(int, fls(delta>>1), 11)); |
| } |
| |
| if(input_pool.entropy_count >= random_read_wakeup_thresh) |
| wake_up_interruptible(&random_read_wait); |
| |
| out: |
| preempt_enable(); |
| } |
| |
| void add_input_randomness(unsigned int type, unsigned int code, |
| unsigned int value) |
| { |
| static unsigned char last_value; |
| |
| /* ignore autorepeat and the like */ |
| if (value == last_value) |
| return; |
| |
| DEBUG_ENT("input event\n"); |
| last_value = value; |
| add_timer_randomness(&input_timer_state, |
| (type << 4) ^ code ^ (code >> 4) ^ value); |
| } |
| |
| void add_interrupt_randomness(int irq) |
| { |
| if (irq >= NR_IRQS || irq_timer_state[irq] == 0) |
| return; |
| |
| DEBUG_ENT("irq event %d\n", irq); |
| add_timer_randomness(irq_timer_state[irq], 0x100 + irq); |
| } |
| |
| #ifdef CONFIG_BLOCK |
| void add_disk_randomness(struct gendisk *disk) |
| { |
| if (!disk || !disk->random) |
| return; |
| /* first major is 1, so we get >= 0x200 here */ |
| DEBUG_ENT("disk event %d:%d\n", disk->major, disk->first_minor); |
| |
| add_timer_randomness(disk->random, |
| 0x100 + MKDEV(disk->major, disk->first_minor)); |
| } |
| |
| EXPORT_SYMBOL(add_disk_randomness); |
| #endif |
| |
| #define EXTRACT_SIZE 10 |
| |
| /********************************************************************* |
| * |
| * Entropy extraction routines |
| * |
| *********************************************************************/ |
| |
| static ssize_t extract_entropy(struct entropy_store *r, void * buf, |
| size_t nbytes, int min, int rsvd); |
| |
| /* |
| * This utility inline function is responsible for transfering entropy |
| * from the primary pool to the secondary extraction pool. We make |
| * sure we pull enough for a 'catastrophic reseed'. |
| */ |
| static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes) |
| { |
| __u32 tmp[OUTPUT_POOL_WORDS]; |
| |
| if (r->pull && r->entropy_count < nbytes * 8 && |
| r->entropy_count < r->poolinfo->POOLBITS) { |
| int bytes = max_t(int, random_read_wakeup_thresh / 8, |
| min_t(int, nbytes, sizeof(tmp))); |
| int rsvd = r->limit ? 0 : random_read_wakeup_thresh/4; |
| |
| DEBUG_ENT("going to reseed %s with %d bits " |
| "(%d of %d requested)\n", |
| r->name, bytes * 8, nbytes * 8, r->entropy_count); |
| |
| bytes=extract_entropy(r->pull, tmp, bytes, |
| random_read_wakeup_thresh / 8, rsvd); |
| add_entropy_words(r, tmp, (bytes + 3) / 4); |
| credit_entropy_store(r, bytes*8); |
| } |
| } |
| |
| /* |
| * These functions extracts randomness from the "entropy pool", and |
| * returns it in a buffer. |
| * |
| * The min parameter specifies the minimum amount we can pull before |
| * failing to avoid races that defeat catastrophic reseeding while the |
| * reserved parameter indicates how much entropy we must leave in the |
| * pool after each pull to avoid starving other readers. |
| * |
| * Note: extract_entropy() assumes that .poolwords is a multiple of 16 words. |
| */ |
| |
| static size_t account(struct entropy_store *r, size_t nbytes, int min, |
| int reserved) |
| { |
| unsigned long flags; |
| |
| BUG_ON(r->entropy_count > r->poolinfo->POOLBITS); |
| |
| /* Hold lock while accounting */ |
| spin_lock_irqsave(&r->lock, flags); |
| |
| DEBUG_ENT("trying to extract %d bits from %s\n", |
| nbytes * 8, r->name); |
| |
| /* Can we pull enough? */ |
| if (r->entropy_count / 8 < min + reserved) { |
| nbytes = 0; |
| } else { |
| /* If limited, never pull more than available */ |
| if (r->limit && nbytes + reserved >= r->entropy_count / 8) |
| nbytes = r->entropy_count/8 - reserved; |
| |
| if(r->entropy_count / 8 >= nbytes + reserved) |
| r->entropy_count -= nbytes*8; |
| else |
| r->entropy_count = reserved; |
| |
| if (r->entropy_count < random_write_wakeup_thresh) |
| wake_up_interruptible(&random_write_wait); |
| } |
| |
| DEBUG_ENT("debiting %d entropy credits from %s%s\n", |
| nbytes * 8, r->name, r->limit ? "" : " (unlimited)"); |
| |
| spin_unlock_irqrestore(&r->lock, flags); |
| |
| return nbytes; |
| } |
| |
| static void extract_buf(struct entropy_store *r, __u8 *out) |
| { |
| int i, x; |
| __u32 data[16], buf[5 + SHA_WORKSPACE_WORDS]; |
| |
| sha_init(buf); |
| /* |
| * As we hash the pool, we mix intermediate values of |
| * the hash back into the pool. This eliminates |
| * backtracking attacks (where the attacker knows |
| * the state of the pool plus the current outputs, and |
| * attempts to find previous ouputs), unless the hash |
| * function can be inverted. |
| */ |
| for (i = 0, x = 0; i < r->poolinfo->poolwords; i += 16, x+=2) { |
| sha_transform(buf, (__u8 *)r->pool+i, buf + 5); |
| add_entropy_words(r, &buf[x % 5], 1); |
| } |
| |
| /* |
| * To avoid duplicates, we atomically extract a |
| * portion of the pool while mixing, and hash one |
| * final time. |
| */ |
| __add_entropy_words(r, &buf[x % 5], 1, data); |
| sha_transform(buf, (__u8 *)data, buf + 5); |
| |
| /* |
| * In case the hash function has some recognizable |
| * output pattern, we fold it in half. |
| */ |
| |
| buf[0] ^= buf[3]; |
| buf[1] ^= buf[4]; |
| buf[0] ^= rol32(buf[3], 16); |
| memcpy(out, buf, EXTRACT_SIZE); |
| memset(buf, 0, sizeof(buf)); |
| } |
| |
| static ssize_t extract_entropy(struct entropy_store *r, void * buf, |
| size_t nbytes, int min, int reserved) |
| { |
| ssize_t ret = 0, i; |
| __u8 tmp[EXTRACT_SIZE]; |
| |
| xfer_secondary_pool(r, nbytes); |
| nbytes = account(r, nbytes, min, reserved); |
| |
| while (nbytes) { |
| extract_buf(r, tmp); |
| i = min_t(int, nbytes, EXTRACT_SIZE); |
| memcpy(buf, tmp, i); |
| nbytes -= i; |
| buf += i; |
| ret += i; |
| } |
| |
| /* Wipe data just returned from memory */ |
| memset(tmp, 0, sizeof(tmp)); |
| |
| return ret; |
| } |
| |
| static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf, |
| size_t nbytes) |
| { |
| ssize_t ret = 0, i; |
| __u8 tmp[EXTRACT_SIZE]; |
| |
| xfer_secondary_pool(r, nbytes); |
| nbytes = account(r, nbytes, 0, 0); |
| |
| while (nbytes) { |
| if (need_resched()) { |
| if (signal_pending(current)) { |
| if (ret == 0) |
| ret = -ERESTARTSYS; |
| break; |
| } |
| schedule(); |
| } |
| |
| extract_buf(r, tmp); |
| i = min_t(int, nbytes, EXTRACT_SIZE); |
| if (copy_to_user(buf, tmp, i)) { |
| ret = -EFAULT; |
| break; |
| } |
| |
| nbytes -= i; |
| buf += i; |
| ret += i; |
| } |
| |
| /* Wipe data just returned from memory */ |
| memset(tmp, 0, sizeof(tmp)); |
| |
| return ret; |
| } |
| |
| /* |
| * This function is the exported kernel interface. It returns some |
| * number of good random numbers, suitable for seeding TCP sequence |
| * numbers, etc. |
| */ |
| void get_random_bytes(void *buf, int nbytes) |
| { |
| extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0); |
| } |
| |
| EXPORT_SYMBOL(get_random_bytes); |
| |
| /* |
| * init_std_data - initialize pool with system data |
| * |
| * @r: pool to initialize |
| * |
| * This function clears the pool's entropy count and mixes some system |
| * data into the pool to prepare it for use. The pool is not cleared |
| * as that can only decrease the entropy in the pool. |
| */ |
| static void init_std_data(struct entropy_store *r) |
| { |
| struct timeval tv; |
| unsigned long flags; |
| |
| spin_lock_irqsave(&r->lock, flags); |
| r->entropy_count = 0; |
| spin_unlock_irqrestore(&r->lock, flags); |
| |
| do_gettimeofday(&tv); |
| add_entropy_words(r, (__u32 *)&tv, sizeof(tv)/4); |
| add_entropy_words(r, (__u32 *)&system_utsname, |
| sizeof(system_utsname)/4); |
| } |
| |
| static int __init rand_initialize(void) |
| { |
| init_std_data(&input_pool); |
| init_std_data(&blocking_pool); |
| init_std_data(&nonblocking_pool); |
| return 0; |
| } |
| module_init(rand_initialize); |
| |
| void rand_initialize_irq(int irq) |
| { |
| struct timer_rand_state *state; |
| |
| if (irq >= NR_IRQS || irq_timer_state[irq]) |
| return; |
| |
| /* |
| * If kmalloc returns null, we just won't use that entropy |
| * source. |
| */ |
| state = kmalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
| if (state) { |
| memset(state, 0, sizeof(struct timer_rand_state)); |
| irq_timer_state[irq] = state; |
| } |
| } |
| |
| #ifdef CONFIG_BLOCK |
| void rand_initialize_disk(struct gendisk *disk) |
| { |
| struct timer_rand_state *state; |
| |
| /* |
| * If kmalloc returns null, we just won't use that entropy |
| * source. |
| */ |
| state = kmalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
| if (state) { |
| memset(state, 0, sizeof(struct timer_rand_state)); |
| disk->random = state; |
| } |
| } |
| #endif |
| |
| static ssize_t |
| random_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos) |
| { |
| ssize_t n, retval = 0, count = 0; |
| |
| if (nbytes == 0) |
| return 0; |
| |
| while (nbytes > 0) { |
| n = nbytes; |
| if (n > SEC_XFER_SIZE) |
| n = SEC_XFER_SIZE; |
| |
| DEBUG_ENT("reading %d bits\n", n*8); |
| |
| n = extract_entropy_user(&blocking_pool, buf, n); |
| |
| DEBUG_ENT("read got %d bits (%d still needed)\n", |
| n*8, (nbytes-n)*8); |
| |
| if (n == 0) { |
| if (file->f_flags & O_NONBLOCK) { |
| retval = -EAGAIN; |
| break; |
| } |
| |
| DEBUG_ENT("sleeping?\n"); |
| |
| wait_event_interruptible(random_read_wait, |
| input_pool.entropy_count >= |
| random_read_wakeup_thresh); |
| |
| DEBUG_ENT("awake\n"); |
| |
| if (signal_pending(current)) { |
| retval = -ERESTARTSYS; |
| break; |
| } |
| |
| continue; |
| } |
| |
| if (n < 0) { |
| retval = n; |
| break; |
| } |
| count += n; |
| buf += n; |
| nbytes -= n; |
| break; /* This break makes the device work */ |
| /* like a named pipe */ |
| } |
| |
| /* |
| * If we gave the user some bytes, update the access time. |
| */ |
| if (count) |
| file_accessed(file); |
| |
| return (count ? count : retval); |
| } |
| |
| static ssize_t |
| urandom_read(struct file * file, char __user * buf, |
| size_t nbytes, loff_t *ppos) |
| { |
| return extract_entropy_user(&nonblocking_pool, buf, nbytes); |
| } |
| |
| static unsigned int |
| random_poll(struct file *file, poll_table * wait) |
| { |
| unsigned int mask; |
| |
| poll_wait(file, &random_read_wait, wait); |
| poll_wait(file, &random_write_wait, wait); |
| mask = 0; |
| if (input_pool.entropy_count >= random_read_wakeup_thresh) |
| mask |= POLLIN | POLLRDNORM; |
| if (input_pool.entropy_count < random_write_wakeup_thresh) |
| mask |= POLLOUT | POLLWRNORM; |
| return mask; |
| } |
| |
| static ssize_t |
| random_write(struct file * file, const char __user * buffer, |
| size_t count, loff_t *ppos) |
| { |
| int ret = 0; |
| size_t bytes; |
| __u32 buf[16]; |
| const char __user *p = buffer; |
| size_t c = count; |
| |
| while (c > 0) { |
| bytes = min(c, sizeof(buf)); |
| |
| bytes -= copy_from_user(&buf, p, bytes); |
| if (!bytes) { |
| ret = -EFAULT; |
| break; |
| } |
| c -= bytes; |
| p += bytes; |
| |
| add_entropy_words(&input_pool, buf, (bytes + 3) / 4); |
| } |
| if (p == buffer) { |
| return (ssize_t)ret; |
| } else { |
| struct inode *inode = file->f_dentry->d_inode; |
| inode->i_mtime = current_fs_time(inode->i_sb); |
| mark_inode_dirty(inode); |
| return (ssize_t)(p - buffer); |
| } |
| } |
| |
| static int |
| random_ioctl(struct inode * inode, struct file * file, |
| unsigned int cmd, unsigned long arg) |
| { |
| int size, ent_count; |
| int __user *p = (int __user *)arg; |
| int retval; |
| |
| switch (cmd) { |
| case RNDGETENTCNT: |
| ent_count = input_pool.entropy_count; |
| if (put_user(ent_count, p)) |
| return -EFAULT; |
| return 0; |
| case RNDADDTOENTCNT: |
| if (!capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| if (get_user(ent_count, p)) |
| return -EFAULT; |
| credit_entropy_store(&input_pool, ent_count); |
| /* |
| * Wake up waiting processes if we have enough |
| * entropy. |
| */ |
| if (input_pool.entropy_count >= random_read_wakeup_thresh) |
| wake_up_interruptible(&random_read_wait); |
| return 0; |
| case RNDADDENTROPY: |
| if (!capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| if (get_user(ent_count, p++)) |
| return -EFAULT; |
| if (ent_count < 0) |
| return -EINVAL; |
| if (get_user(size, p++)) |
| return -EFAULT; |
| retval = random_write(file, (const char __user *) p, |
| size, &file->f_pos); |
| if (retval < 0) |
| return retval; |
| credit_entropy_store(&input_pool, ent_count); |
| /* |
| * Wake up waiting processes if we have enough |
| * entropy. |
| */ |
| if (input_pool.entropy_count >= random_read_wakeup_thresh) |
| wake_up_interruptible(&random_read_wait); |
| return 0; |
| case RNDZAPENTCNT: |
| case RNDCLEARPOOL: |
| /* Clear the entropy pool counters. */ |
| if (!capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| init_std_data(&input_pool); |
| init_std_data(&blocking_pool); |
| init_std_data(&nonblocking_pool); |
| return 0; |
| default: |
| return -EINVAL; |
| } |
| } |
| |
| struct file_operations random_fops = { |
| .read = random_read, |
| .write = random_write, |
| .poll = random_poll, |
| .ioctl = random_ioctl, |
| }; |
| |
| struct file_operations urandom_fops = { |
| .read = urandom_read, |
| .write = random_write, |
| .ioctl = random_ioctl, |
| }; |
| |
| /*************************************************************** |
| * Random UUID interface |
| * |
| * Used here for a Boot ID, but can be useful for other kernel |
| * drivers. |
| ***************************************************************/ |
| |
| /* |
| * Generate random UUID |
| */ |
| void generate_random_uuid(unsigned char uuid_out[16]) |
| { |
| get_random_bytes(uuid_out, 16); |
| /* Set UUID version to 4 --- truely random generation */ |
| uuid_out[6] = (uuid_out[6] & 0x0F) | 0x40; |
| /* Set the UUID variant to DCE */ |
| uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80; |
| } |
| |
| EXPORT_SYMBOL(generate_random_uuid); |
| |
| /******************************************************************** |
| * |
| * Sysctl interface |
| * |
| ********************************************************************/ |
| |
| #ifdef CONFIG_SYSCTL |
| |
| #include <linux/sysctl.h> |
| |
| static int min_read_thresh = 8, min_write_thresh; |
| static int max_read_thresh = INPUT_POOL_WORDS * 32; |
| static int max_write_thresh = INPUT_POOL_WORDS * 32; |
| static char sysctl_bootid[16]; |
| |
| /* |
| * These functions is used to return both the bootid UUID, and random |
| * UUID. The difference is in whether table->data is NULL; if it is, |
| * then a new UUID is generated and returned to the user. |
| * |
| * If the user accesses this via the proc interface, it will be returned |
| * as an ASCII string in the standard UUID format. If accesses via the |
| * sysctl system call, it is returned as 16 bytes of binary data. |
| */ |
| static int proc_do_uuid(ctl_table *table, int write, struct file *filp, |
| void __user *buffer, size_t *lenp, loff_t *ppos) |
| { |
| ctl_table fake_table; |
| unsigned char buf[64], tmp_uuid[16], *uuid; |
| |
| uuid = table->data; |
| if (!uuid) { |
| uuid = tmp_uuid; |
| uuid[8] = 0; |
| } |
| if (uuid[8] == 0) |
| generate_random_uuid(uuid); |
| |
| sprintf(buf, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-" |
| "%02x%02x%02x%02x%02x%02x", |
| uuid[0], uuid[1], uuid[2], uuid[3], |
| uuid[4], uuid[5], uuid[6], uuid[7], |
| uuid[8], uuid[9], uuid[10], uuid[11], |
| uuid[12], uuid[13], uuid[14], uuid[15]); |
| fake_table.data = buf; |
| fake_table.maxlen = sizeof(buf); |
| |
| return proc_dostring(&fake_table, write, filp, buffer, lenp, ppos); |
| } |
| |
| static int uuid_strategy(ctl_table *table, int __user *name, int nlen, |
| void __user *oldval, size_t __user *oldlenp, |
| void __user *newval, size_t newlen, void **context) |
| { |
| unsigned char tmp_uuid[16], *uuid; |
| unsigned int len; |
| |
| if (!oldval || !oldlenp) |
| return 1; |
| |
| uuid = table->data; |
| if (!uuid) { |
| uuid = tmp_uuid; |
| uuid[8] = 0; |
| } |
| if (uuid[8] == 0) |
| generate_random_uuid(uuid); |
| |
| if (get_user(len, oldlenp)) |
| return -EFAULT; |
| if (len) { |
| if (len > 16) |
| len = 16; |
| if (copy_to_user(oldval, uuid, len) || |
| put_user(len, oldlenp)) |
| return -EFAULT; |
| } |
| return 1; |
| } |
| |
| static int sysctl_poolsize = INPUT_POOL_WORDS * 32; |
| ctl_table random_table[] = { |
| { |
| .ctl_name = RANDOM_POOLSIZE, |
| .procname = "poolsize", |
| .data = &sysctl_poolsize, |
| .maxlen = sizeof(int), |
| .mode = 0444, |
| .proc_handler = &proc_dointvec, |
| }, |
| { |
| .ctl_name = RANDOM_ENTROPY_COUNT, |
| .procname = "entropy_avail", |
| .maxlen = sizeof(int), |
| .mode = 0444, |
| .proc_handler = &proc_dointvec, |
| .data = &input_pool.entropy_count, |
| }, |
| { |
| .ctl_name = RANDOM_READ_THRESH, |
| .procname = "read_wakeup_threshold", |
| .data = &random_read_wakeup_thresh, |
| .maxlen = sizeof(int), |
| .mode = 0644, |
| .proc_handler = &proc_dointvec_minmax, |
| .strategy = &sysctl_intvec, |
| .extra1 = &min_read_thresh, |
| .extra2 = &max_read_thresh, |
| }, |
| { |
| .ctl_name = RANDOM_WRITE_THRESH, |
| .procname = "write_wakeup_threshold", |
| .data = &random_write_wakeup_thresh, |
| .maxlen = sizeof(int), |
| .mode = 0644, |
| .proc_handler = &proc_dointvec_minmax, |
| .strategy = &sysctl_intvec, |
| .extra1 = &min_write_thresh, |
| .extra2 = &max_write_thresh, |
| }, |
| { |
| .ctl_name = RANDOM_BOOT_ID, |
| .procname = "boot_id", |
| .data = &sysctl_bootid, |
| .maxlen = 16, |
| .mode = 0444, |
| .proc_handler = &proc_do_uuid, |
| .strategy = &uuid_strategy, |
| }, |
| { |
| .ctl_name = RANDOM_UUID, |
| .procname = "uuid", |
| .maxlen = 16, |
| .mode = 0444, |
| .proc_handler = &proc_do_uuid, |
| .strategy = &uuid_strategy, |
| }, |
| { .ctl_name = 0 } |
| }; |
| #endif /* CONFIG_SYSCTL */ |
| |
| /******************************************************************** |
| * |
| * Random funtions for networking |
| * |
| ********************************************************************/ |
| |
| /* |
| * TCP initial sequence number picking. This uses the random number |
| * generator to pick an initial secret value. This value is hashed |
| * along with the TCP endpoint information to provide a unique |
| * starting point for each pair of TCP endpoints. This defeats |
| * attacks which rely on guessing the initial TCP sequence number. |
| * This algorithm was suggested by Steve Bellovin. |
| * |
| * Using a very strong hash was taking an appreciable amount of the total |
| * TCP connection establishment time, so this is a weaker hash, |
| * compensated for by changing the secret periodically. |
| */ |
| |
| /* F, G and H are basic MD4 functions: selection, majority, parity */ |
| #define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z)))) |
| #define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z))) |
| #define H(x, y, z) ((x) ^ (y) ^ (z)) |
| |
| /* |
| * The generic round function. The application is so specific that |
| * we don't bother protecting all the arguments with parens, as is generally |
| * good macro practice, in favor of extra legibility. |
| * Rotation is separate from addition to prevent recomputation |
| */ |
| #define ROUND(f, a, b, c, d, x, s) \ |
| (a += f(b, c, d) + x, a = (a << s) | (a >> (32 - s))) |
| #define K1 0 |
| #define K2 013240474631UL |
| #define K3 015666365641UL |
| |
| #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) |
| |
| static __u32 twothirdsMD4Transform (__u32 const buf[4], __u32 const in[12]) |
| { |
| __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3]; |
| |
| /* Round 1 */ |
| ROUND(F, a, b, c, d, in[ 0] + K1, 3); |
| ROUND(F, d, a, b, c, in[ 1] + K1, 7); |
| ROUND(F, c, d, a, b, in[ 2] + K1, 11); |
| ROUND(F, b, c, d, a, in[ 3] + K1, 19); |
| ROUND(F, a, b, c, d, in[ 4] + K1, 3); |
| ROUND(F, d, a, b, c, in[ 5] + K1, 7); |
| ROUND(F, c, d, a, b, in[ 6] + K1, 11); |
| ROUND(F, b, c, d, a, in[ 7] + K1, 19); |
| ROUND(F, a, b, c, d, in[ 8] + K1, 3); |
| ROUND(F, d, a, b, c, in[ 9] + K1, 7); |
| ROUND(F, c, d, a, b, in[10] + K1, 11); |
| ROUND(F, b, c, d, a, in[11] + K1, 19); |
| |
| /* Round 2 */ |
| ROUND(G, a, b, c, d, in[ 1] + K2, 3); |
| ROUND(G, d, a, b, c, in[ 3] + K2, 5); |
| ROUND(G, c, d, a, b, in[ 5] + K2, 9); |
| ROUND(G, b, c, d, a, in[ 7] + K2, 13); |
| ROUND(G, a, b, c, d, in[ 9] + K2, 3); |
| ROUND(G, d, a, b, c, in[11] + K2, 5); |
| ROUND(G, c, d, a, b, in[ 0] + K2, 9); |
| ROUND(G, b, c, d, a, in[ 2] + K2, 13); |
| ROUND(G, a, b, c, d, in[ 4] + K2, 3); |
| ROUND(G, d, a, b, c, in[ 6] + K2, 5); |
| ROUND(G, c, d, a, b, in[ 8] + K2, 9); |
| ROUND(G, b, c, d, a, in[10] + K2, 13); |
| |
| /* Round 3 */ |
| ROUND(H, a, b, c, d, in[ 3] + K3, 3); |
| ROUND(H, d, a, b, c, in[ 7] + K3, 9); |
| ROUND(H, c, d, a, b, in[11] + K3, 11); |
| ROUND(H, b, c, d, a, in[ 2] + K3, 15); |
| ROUND(H, a, b, c, d, in[ 6] + K3, 3); |
| ROUND(H, d, a, b, c, in[10] + K3, 9); |
| ROUND(H, c, d, a, b, in[ 1] + K3, 11); |
| ROUND(H, b, c, d, a, in[ 5] + K3, 15); |
| ROUND(H, a, b, c, d, in[ 9] + K3, 3); |
| ROUND(H, d, a, b, c, in[ 0] + K3, 9); |
| ROUND(H, c, d, a, b, in[ 4] + K3, 11); |
| ROUND(H, b, c, d, a, in[ 8] + K3, 15); |
| |
| return buf[1] + b; /* "most hashed" word */ |
| /* Alternative: return sum of all words? */ |
| } |
| #endif |
| |
| #undef ROUND |
| #undef F |
| #undef G |
| #undef H |
| #undef K1 |
| #undef K2 |
| #undef K3 |
| |
| /* This should not be decreased so low that ISNs wrap too fast. */ |
| #define REKEY_INTERVAL (300 * HZ) |
| /* |
| * Bit layout of the tcp sequence numbers (before adding current time): |
| * bit 24-31: increased after every key exchange |
| * bit 0-23: hash(source,dest) |
| * |
| * The implementation is similar to the algorithm described |
| * in the Appendix of RFC 1185, except that |
| * - it uses a 1 MHz clock instead of a 250 kHz clock |
| * - it performs a rekey every 5 minutes, which is equivalent |
| * to a (source,dest) tulple dependent forward jump of the |
| * clock by 0..2^(HASH_BITS+1) |
| * |
| * Thus the average ISN wraparound time is 68 minutes instead of |
| * 4.55 hours. |
| * |
| * SMP cleanup and lock avoidance with poor man's RCU. |
| * Manfred Spraul <manfred@colorfullife.com> |
| * |
| */ |
| #define COUNT_BITS 8 |
| #define COUNT_MASK ((1 << COUNT_BITS) - 1) |
| #define HASH_BITS 24 |
| #define HASH_MASK ((1 << HASH_BITS) - 1) |
| |
| static struct keydata { |
| __u32 count; /* already shifted to the final position */ |
| __u32 secret[12]; |
| } ____cacheline_aligned ip_keydata[2]; |
| |
| static unsigned int ip_cnt; |
| |
| static void rekey_seq_generator(void *private_); |
| |
| static DECLARE_WORK(rekey_work, rekey_seq_generator, NULL); |
| |
| /* |
| * Lock avoidance: |
| * The ISN generation runs lockless - it's just a hash over random data. |
| * State changes happen every 5 minutes when the random key is replaced. |
| * Synchronization is performed by having two copies of the hash function |
| * state and rekey_seq_generator always updates the inactive copy. |
| * The copy is then activated by updating ip_cnt. |
| * The implementation breaks down if someone blocks the thread |
| * that processes SYN requests for more than 5 minutes. Should never |
| * happen, and even if that happens only a not perfectly compliant |
| * ISN is generated, nothing fatal. |
| */ |
| static void rekey_seq_generator(void *private_) |
| { |
| struct keydata *keyptr = &ip_keydata[1 ^ (ip_cnt & 1)]; |
| |
| get_random_bytes(keyptr->secret, sizeof(keyptr->secret)); |
| keyptr->count = (ip_cnt & COUNT_MASK) << HASH_BITS; |
| smp_wmb(); |
| ip_cnt++; |
| schedule_delayed_work(&rekey_work, REKEY_INTERVAL); |
| } |
| |
| static inline struct keydata *get_keyptr(void) |
| { |
| struct keydata *keyptr = &ip_keydata[ip_cnt & 1]; |
| |
| smp_rmb(); |
| |
| return keyptr; |
| } |
| |
| static __init int seqgen_init(void) |
| { |
| rekey_seq_generator(NULL); |
| return 0; |
| } |
| late_initcall(seqgen_init); |
| |
| #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) |
| __u32 secure_tcpv6_sequence_number(__u32 *saddr, __u32 *daddr, |
| __u16 sport, __u16 dport) |
| { |
| struct timeval tv; |
| __u32 seq; |
| __u32 hash[12]; |
| struct keydata *keyptr = get_keyptr(); |
| |
| /* The procedure is the same as for IPv4, but addresses are longer. |
| * Thus we must use twothirdsMD4Transform. |
| */ |
| |
| memcpy(hash, saddr, 16); |
| hash[4]=(sport << 16) + dport; |
| memcpy(&hash[5],keyptr->secret,sizeof(__u32) * 7); |
| |
| seq = twothirdsMD4Transform(daddr, hash) & HASH_MASK; |
| seq += keyptr->count; |
| |
| do_gettimeofday(&tv); |
| seq += tv.tv_usec + tv.tv_sec * 1000000; |
| |
| return seq; |
| } |
| EXPORT_SYMBOL(secure_tcpv6_sequence_number); |
| #endif |
| |
| /* The code below is shamelessly stolen from secure_tcp_sequence_number(). |
| * All blames to Andrey V. Savochkin <saw@msu.ru>. |
| */ |
| __u32 secure_ip_id(__u32 daddr) |
| { |
| struct keydata *keyptr; |
| __u32 hash[4]; |
| |
| keyptr = get_keyptr(); |
| |
| /* |
| * Pick a unique starting offset for each IP destination. |
| * The dest ip address is placed in the starting vector, |
| * which is then hashed with random data. |
| */ |
| hash[0] = daddr; |
| hash[1] = keyptr->secret[9]; |
| hash[2] = keyptr->secret[10]; |
| hash[3] = keyptr->secret[11]; |
| |
| return half_md4_transform(hash, keyptr->secret); |
| } |
| |
| #ifdef CONFIG_INET |
| |
| __u32 secure_tcp_sequence_number(__u32 saddr, __u32 daddr, |
| __u16 sport, __u16 dport) |
| { |
| struct timeval tv; |
| __u32 seq; |
| __u32 hash[4]; |
| struct keydata *keyptr = get_keyptr(); |
| |
| /* |
| * Pick a unique starting offset for each TCP connection endpoints |
| * (saddr, daddr, sport, dport). |
| * Note that the words are placed into the starting vector, which is |
| * then mixed with a partial MD4 over random data. |
| */ |
| hash[0]=saddr; |
| hash[1]=daddr; |
| hash[2]=(sport << 16) + dport; |
| hash[3]=keyptr->secret[11]; |
| |
| seq = half_md4_transform(hash, keyptr->secret) & HASH_MASK; |
| seq += keyptr->count; |
| /* |
| * As close as possible to RFC 793, which |
| * suggests using a 250 kHz clock. |
| * Further reading shows this assumes 2 Mb/s networks. |
| * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate. |
| * That's funny, Linux has one built in! Use it! |
| * (Networks are faster now - should this be increased?) |
| */ |
| do_gettimeofday(&tv); |
| seq += tv.tv_usec + tv.tv_sec * 1000000; |
| #if 0 |
| printk("init_seq(%lx, %lx, %d, %d) = %d\n", |
| saddr, daddr, sport, dport, seq); |
| #endif |
| return seq; |
| } |
| |
| EXPORT_SYMBOL(secure_tcp_sequence_number); |
| |
| /* Generate secure starting point for ephemeral IPV4 transport port search */ |
| u32 secure_ipv4_port_ephemeral(__u32 saddr, __u32 daddr, __u16 dport) |
| { |
| struct keydata *keyptr = get_keyptr(); |
| u32 hash[4]; |
| |
| /* |
| * Pick a unique starting offset for each ephemeral port search |
| * (saddr, daddr, dport) and 48bits of random data. |
| */ |
| hash[0] = saddr; |
| hash[1] = daddr; |
| hash[2] = dport ^ keyptr->secret[10]; |
| hash[3] = keyptr->secret[11]; |
| |
| return half_md4_transform(hash, keyptr->secret); |
| } |
| |
| #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) |
| u32 secure_ipv6_port_ephemeral(const __u32 *saddr, const __u32 *daddr, __u16 dport) |
| { |
| struct keydata *keyptr = get_keyptr(); |
| u32 hash[12]; |
| |
| memcpy(hash, saddr, 16); |
| hash[4] = dport; |
| memcpy(&hash[5],keyptr->secret,sizeof(__u32) * 7); |
| |
| return twothirdsMD4Transform(daddr, hash); |
| } |
| #endif |
| |
| #if defined(CONFIG_IP_DCCP) || defined(CONFIG_IP_DCCP_MODULE) |
| /* Similar to secure_tcp_sequence_number but generate a 48 bit value |
| * bit's 32-47 increase every key exchange |
| * 0-31 hash(source, dest) |
| */ |
| u64 secure_dccp_sequence_number(__u32 saddr, __u32 daddr, |
| __u16 sport, __u16 dport) |
| { |
| struct timeval tv; |
| u64 seq; |
| __u32 hash[4]; |
| struct keydata *keyptr = get_keyptr(); |
| |
| hash[0] = saddr; |
| hash[1] = daddr; |
| hash[2] = (sport << 16) + dport; |
| hash[3] = keyptr->secret[11]; |
| |
| seq = half_md4_transform(hash, keyptr->secret); |
| seq |= ((u64)keyptr->count) << (32 - HASH_BITS); |
| |
| do_gettimeofday(&tv); |
| seq += tv.tv_usec + tv.tv_sec * 1000000; |
| seq &= (1ull << 48) - 1; |
| #if 0 |
| printk("dccp init_seq(%lx, %lx, %d, %d) = %d\n", |
| saddr, daddr, sport, dport, seq); |
| #endif |
| return seq; |
| } |
| |
| EXPORT_SYMBOL(secure_dccp_sequence_number); |
| #endif |
| |
| #endif /* CONFIG_INET */ |
| |
| |
| /* |
| * Get a random word for internal kernel use only. Similar to urandom but |
| * with the goal of minimal entropy pool depletion. As a result, the random |
| * value is not cryptographically secure but for several uses the cost of |
| * depleting entropy is too high |
| */ |
| unsigned int get_random_int(void) |
| { |
| /* |
| * Use IP's RNG. It suits our purpose perfectly: it re-keys itself |
| * every second, from the entropy pool (and thus creates a limited |
| * drain on it), and uses halfMD4Transform within the second. We |
| * also mix it with jiffies and the PID: |
| */ |
| return secure_ip_id(current->pid + jiffies); |
| } |
| |
| /* |
| * randomize_range() returns a start address such that |
| * |
| * [...... <range> .....] |
| * start end |
| * |
| * a <range> with size "len" starting at the return value is inside in the |
| * area defined by [start, end], but is otherwise randomized. |
| */ |
| unsigned long |
| randomize_range(unsigned long start, unsigned long end, unsigned long len) |
| { |
| unsigned long range = end - len - start; |
| |
| if (end <= start + len) |
| return 0; |
| return PAGE_ALIGN(get_random_int() % range + start); |
| } |