| 1 | /* |
| 2 | * random.c -- A strong random number generator |
| 3 | * |
| 4 | * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005 |
| 5 | * |
| 6 | * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All |
| 7 | * rights reserved. |
| 8 | * |
| 9 | * Redistribution and use in source and binary forms, with or without |
| 10 | * modification, are permitted provided that the following conditions |
| 11 | * are met: |
| 12 | * 1. Redistributions of source code must retain the above copyright |
| 13 | * notice, and the entire permission notice in its entirety, |
| 14 | * including the disclaimer of warranties. |
| 15 | * 2. Redistributions in binary form must reproduce the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer in the |
| 17 | * documentation and/or other materials provided with the distribution. |
| 18 | * 3. The name of the author may not be used to endorse or promote |
| 19 | * products derived from this software without specific prior |
| 20 | * written permission. |
| 21 | * |
| 22 | * ALTERNATIVELY, this product may be distributed under the terms of |
| 23 | * the GNU General Public License, in which case the provisions of the GPL are |
| 24 | * required INSTEAD OF the above restrictions. (This clause is |
| 25 | * necessary due to a potential bad interaction between the GPL and |
| 26 | * the restrictions contained in a BSD-style copyright.) |
| 27 | * |
| 28 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| 29 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 30 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF |
| 31 | * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE |
| 32 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 33 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT |
| 34 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
| 35 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| 36 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 37 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE |
| 38 | * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH |
| 39 | * DAMAGE. |
| 40 | */ |
| 41 | |
| 42 | /* |
| 43 | * (now, with legal B.S. out of the way.....) |
| 44 | * |
| 45 | * This routine gathers environmental noise from device drivers, etc., |
| 46 | * and returns good random numbers, suitable for cryptographic use. |
| 47 | * Besides the obvious cryptographic uses, these numbers are also good |
| 48 | * for seeding TCP sequence numbers, and other places where it is |
| 49 | * desirable to have numbers which are not only random, but hard to |
| 50 | * predict by an attacker. |
| 51 | * |
| 52 | * Theory of operation |
| 53 | * =================== |
| 54 | * |
| 55 | * Computers are very predictable devices. Hence it is extremely hard |
| 56 | * to produce truly random numbers on a computer --- as opposed to |
| 57 | * pseudo-random numbers, which can easily generated by using a |
| 58 | * algorithm. Unfortunately, it is very easy for attackers to guess |
| 59 | * the sequence of pseudo-random number generators, and for some |
| 60 | * applications this is not acceptable. So instead, we must try to |
| 61 | * gather "environmental noise" from the computer's environment, which |
| 62 | * must be hard for outside attackers to observe, and use that to |
| 63 | * generate random numbers. In a Unix environment, this is best done |
| 64 | * from inside the kernel. |
| 65 | * |
| 66 | * Sources of randomness from the environment include inter-keyboard |
| 67 | * timings, inter-interrupt timings from some interrupts, and other |
| 68 | * events which are both (a) non-deterministic and (b) hard for an |
| 69 | * outside observer to measure. Randomness from these sources are |
| 70 | * added to an "entropy pool", which is mixed using a CRC-like function. |
| 71 | * This is not cryptographically strong, but it is adequate assuming |
| 72 | * the randomness is not chosen maliciously, and it is fast enough that |
| 73 | * the overhead of doing it on every interrupt is very reasonable. |
| 74 | * As random bytes are mixed into the entropy pool, the routines keep |
| 75 | * an *estimate* of how many bits of randomness have been stored into |
| 76 | * the random number generator's internal state. |
| 77 | * |
| 78 | * When random bytes are desired, they are obtained by taking the SHA |
| 79 | * hash of the contents of the "entropy pool". The SHA hash avoids |
| 80 | * exposing the internal state of the entropy pool. It is believed to |
| 81 | * be computationally infeasible to derive any useful information |
| 82 | * about the input of SHA from its output. Even if it is possible to |
| 83 | * analyze SHA in some clever way, as long as the amount of data |
| 84 | * returned from the generator is less than the inherent entropy in |
| 85 | * the pool, the output data is totally unpredictable. For this |
| 86 | * reason, the routine decreases its internal estimate of how many |
| 87 | * bits of "true randomness" are contained in the entropy pool as it |
| 88 | * outputs random numbers. |
| 89 | * |
| 90 | * If this estimate goes to zero, the routine can still generate |
| 91 | * random numbers; however, an attacker may (at least in theory) be |
| 92 | * able to infer the future output of the generator from prior |
| 93 | * outputs. This requires successful cryptanalysis of SHA, which is |
| 94 | * not believed to be feasible, but there is a remote possibility. |
| 95 | * Nonetheless, these numbers should be useful for the vast majority |
| 96 | * of purposes. |
| 97 | * |
| 98 | * Exported interfaces ---- output |
| 99 | * =============================== |
| 100 | * |
| 101 | * There are three exported interfaces; the first is one designed to |
| 102 | * be used from within the kernel: |
| 103 | * |
| 104 | * void get_random_bytes(void *buf, int nbytes); |
| 105 | * |
| 106 | * This interface will return the requested number of random bytes, |
| 107 | * and place it in the requested buffer. |
| 108 | * |
| 109 | * The two other interfaces are two character devices /dev/random and |
| 110 | * /dev/urandom. /dev/random is suitable for use when very high |
| 111 | * quality randomness is desired (for example, for key generation or |
| 112 | * one-time pads), as it will only return a maximum of the number of |
| 113 | * bits of randomness (as estimated by the random number generator) |
| 114 | * contained in the entropy pool. |
| 115 | * |
| 116 | * The /dev/urandom device does not have this limit, and will return |
| 117 | * as many bytes as are requested. As more and more random bytes are |
| 118 | * requested without giving time for the entropy pool to recharge, |
| 119 | * this will result in random numbers that are merely cryptographically |
| 120 | * strong. For many applications, however, this is acceptable. |
| 121 | * |
| 122 | * Exported interfaces ---- input |
| 123 | * ============================== |
| 124 | * |
| 125 | * The current exported interfaces for gathering environmental noise |
| 126 | * from the devices are: |
| 127 | * |
| 128 | * void add_input_randomness(unsigned int type, unsigned int code, |
| 129 | * unsigned int value); |
| 130 | * void add_interrupt_randomness(int irq); |
| 131 | * |
| 132 | * add_input_randomness() uses the input layer interrupt timing, as well as |
| 133 | * the event type information from the hardware. |
| 134 | * |
| 135 | * add_interrupt_randomness() uses the inter-interrupt timing as random |
| 136 | * inputs to the entropy pool. Note that not all interrupts are good |
| 137 | * sources of randomness! For example, the timer interrupts is not a |
| 138 | * good choice, because the periodicity of the interrupts is too |
| 139 | * regular, and hence predictable to an attacker. Disk interrupts are |
| 140 | * a better measure, since the timing of the disk interrupts are more |
| 141 | * unpredictable. |
| 142 | * |
| 143 | * All of these routines try to estimate how many bits of randomness a |
| 144 | * particular randomness source. They do this by keeping track of the |
| 145 | * first and second order deltas of the event timings. |
| 146 | * |
| 147 | * Ensuring unpredictability at system startup |
| 148 | * ============================================ |
| 149 | * |
| 150 | * When any operating system starts up, it will go through a sequence |
| 151 | * of actions that are fairly predictable by an adversary, especially |
| 152 | * if the start-up does not involve interaction with a human operator. |
| 153 | * This reduces the actual number of bits of unpredictability in the |
| 154 | * entropy pool below the value in entropy_count. In order to |
| 155 | * counteract this effect, it helps to carry information in the |
| 156 | * entropy pool across shut-downs and start-ups. To do this, put the |
| 157 | * following lines an appropriate script which is run during the boot |
| 158 | * sequence: |
| 159 | * |
| 160 | * echo "Initializing random number generator..." |
| 161 | * random_seed=/var/run/random-seed |
| 162 | * # Carry a random seed from start-up to start-up |
| 163 | * # Load and then save the whole entropy pool |
| 164 | * if [ -f $random_seed ]; then |
| 165 | * cat $random_seed >/dev/urandom |
| 166 | * else |
| 167 | * touch $random_seed |
| 168 | * fi |
| 169 | * chmod 600 $random_seed |
| 170 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 |
| 171 | * |
| 172 | * and the following lines in an appropriate script which is run as |
| 173 | * the system is shutdown: |
| 174 | * |
| 175 | * # Carry a random seed from shut-down to start-up |
| 176 | * # Save the whole entropy pool |
| 177 | * echo "Saving random seed..." |
| 178 | * random_seed=/var/run/random-seed |
| 179 | * touch $random_seed |
| 180 | * chmod 600 $random_seed |
| 181 | * dd if=/dev/urandom of=$random_seed count=1 bs=512 |
| 182 | * |
| 183 | * For example, on most modern systems using the System V init |
| 184 | * scripts, such code fragments would be found in |
| 185 | * /etc/rc.d/init.d/random. On older Linux systems, the correct script |
| 186 | * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0. |
| 187 | * |
| 188 | * Effectively, these commands cause the contents of the entropy pool |
| 189 | * to be saved at shut-down time and reloaded into the entropy pool at |
| 190 | * start-up. (The 'dd' in the addition to the bootup script is to |
| 191 | * make sure that /etc/random-seed is different for every start-up, |
| 192 | * even if the system crashes without executing rc.0.) Even with |
| 193 | * complete knowledge of the start-up activities, predicting the state |
| 194 | * of the entropy pool requires knowledge of the previous history of |
| 195 | * the system. |
| 196 | * |
| 197 | * Configuring the /dev/random driver under Linux |
| 198 | * ============================================== |
| 199 | * |
| 200 | * The /dev/random driver under Linux uses minor numbers 8 and 9 of |
| 201 | * the /dev/mem major number (#1). So if your system does not have |
| 202 | * /dev/random and /dev/urandom created already, they can be created |
| 203 | * by using the commands: |
| 204 | * |
| 205 | * mknod /dev/random c 1 8 |
| 206 | * mknod /dev/urandom c 1 9 |
| 207 | * |
| 208 | * Acknowledgements: |
| 209 | * ================= |
| 210 | * |
| 211 | * Ideas for constructing this random number generator were derived |
| 212 | * from Pretty Good Privacy's random number generator, and from private |
| 213 | * discussions with Phil Karn. Colin Plumb provided a faster random |
| 214 | * number generator, which speed up the mixing function of the entropy |
| 215 | * pool, taken from PGPfone. Dale Worley has also contributed many |
| 216 | * useful ideas and suggestions to improve this driver. |
| 217 | * |
| 218 | * Any flaws in the design are solely my responsibility, and should |
| 219 | * not be attributed to the Phil, Colin, or any of authors of PGP. |
| 220 | * |
| 221 | * Further background information on this topic may be obtained from |
| 222 | * RFC 1750, "Randomness Recommendations for Security", by Donald |
| 223 | * Eastlake, Steve Crocker, and Jeff Schiller. |
| 224 | */ |
| 225 | |
| 226 | #include <linux/utsname.h> |
| 227 | #include <linux/module.h> |
| 228 | #include <linux/kernel.h> |
| 229 | #include <linux/major.h> |
| 230 | #include <linux/string.h> |
| 231 | #include <linux/fcntl.h> |
| 232 | #include <linux/slab.h> |
| 233 | #include <linux/random.h> |
| 234 | #include <linux/poll.h> |
| 235 | #include <linux/init.h> |
| 236 | #include <linux/fs.h> |
| 237 | #include <linux/genhd.h> |
| 238 | #include <linux/interrupt.h> |
| 239 | #include <linux/mm.h> |
| 240 | #include <linux/spinlock.h> |
| 241 | #include <linux/percpu.h> |
| 242 | #include <linux/cryptohash.h> |
| 243 | #include <linux/fips.h> |
| 244 | |
| 245 | #ifdef CONFIG_GENERIC_HARDIRQS |
| 246 | # include <linux/irq.h> |
| 247 | #endif |
| 248 | |
| 249 | #include <asm/processor.h> |
| 250 | #include <asm/uaccess.h> |
| 251 | #include <asm/irq.h> |
| 252 | #include <asm/io.h> |
| 253 | |
| 254 | /* |
| 255 | * Configuration information |
| 256 | */ |
| 257 | #define INPUT_POOL_WORDS 128 |
| 258 | #define OUTPUT_POOL_WORDS 32 |
| 259 | #define SEC_XFER_SIZE 512 |
| 260 | |
| 261 | /* |
| 262 | * The minimum number of bits of entropy before we wake up a read on |
| 263 | * /dev/random. Should be enough to do a significant reseed. |
| 264 | */ |
| 265 | static int random_read_wakeup_thresh = 64; |
| 266 | |
| 267 | /* |
| 268 | * If the entropy count falls under this number of bits, then we |
| 269 | * should wake up processes which are selecting or polling on write |
| 270 | * access to /dev/random. |
| 271 | */ |
| 272 | static int random_write_wakeup_thresh = 128; |
| 273 | |
| 274 | /* |
| 275 | * When the input pool goes over trickle_thresh, start dropping most |
| 276 | * samples to avoid wasting CPU time and reduce lock contention. |
| 277 | */ |
| 278 | |
| 279 | static int trickle_thresh __read_mostly = INPUT_POOL_WORDS * 28; |
| 280 | |
| 281 | static DEFINE_PER_CPU(int, trickle_count); |
| 282 | |
| 283 | /* |
| 284 | * A pool of size .poolwords is stirred with a primitive polynomial |
| 285 | * of degree .poolwords over GF(2). The taps for various sizes are |
| 286 | * defined below. They are chosen to be evenly spaced (minimum RMS |
| 287 | * distance from evenly spaced; the numbers in the comments are a |
| 288 | * scaled squared error sum) except for the last tap, which is 1 to |
| 289 | * get the twisting happening as fast as possible. |
| 290 | */ |
| 291 | static struct poolinfo { |
| 292 | int poolwords; |
| 293 | int tap1, tap2, tap3, tap4, tap5; |
| 294 | } poolinfo_table[] = { |
| 295 | /* x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 -- 105 */ |
| 296 | { 128, 103, 76, 51, 25, 1 }, |
| 297 | /* x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 -- 15 */ |
| 298 | { 32, 26, 20, 14, 7, 1 }, |
| 299 | #if 0 |
| 300 | /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */ |
| 301 | { 2048, 1638, 1231, 819, 411, 1 }, |
| 302 | |
| 303 | /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */ |
| 304 | { 1024, 817, 615, 412, 204, 1 }, |
| 305 | |
| 306 | /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */ |
| 307 | { 1024, 819, 616, 410, 207, 2 }, |
| 308 | |
| 309 | /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */ |
| 310 | { 512, 411, 308, 208, 104, 1 }, |
| 311 | |
| 312 | /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */ |
| 313 | { 512, 409, 307, 206, 102, 2 }, |
| 314 | /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */ |
| 315 | { 512, 409, 309, 205, 103, 2 }, |
| 316 | |
| 317 | /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */ |
| 318 | { 256, 205, 155, 101, 52, 1 }, |
| 319 | |
| 320 | /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */ |
| 321 | { 128, 103, 78, 51, 27, 2 }, |
| 322 | |
| 323 | /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */ |
| 324 | { 64, 52, 39, 26, 14, 1 }, |
| 325 | #endif |
| 326 | }; |
| 327 | |
| 328 | #define POOLBITS poolwords*32 |
| 329 | #define POOLBYTES poolwords*4 |
| 330 | |
| 331 | /* |
| 332 | * For the purposes of better mixing, we use the CRC-32 polynomial as |
| 333 | * well to make a twisted Generalized Feedback Shift Reigster |
| 334 | * |
| 335 | * (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR generators. ACM |
| 336 | * Transactions on Modeling and Computer Simulation 2(3):179-194. |
| 337 | * Also see M. Matsumoto & Y. Kurita, 1994. Twisted GFSR generators |
| 338 | * II. ACM Transactions on Mdeling and Computer Simulation 4:254-266) |
| 339 | * |
| 340 | * Thanks to Colin Plumb for suggesting this. |
| 341 | * |
| 342 | * We have not analyzed the resultant polynomial to prove it primitive; |
| 343 | * in fact it almost certainly isn't. Nonetheless, the irreducible factors |
| 344 | * of a random large-degree polynomial over GF(2) are more than large enough |
| 345 | * that periodicity is not a concern. |
| 346 | * |
| 347 | * The input hash is much less sensitive than the output hash. All |
| 348 | * that we want of it is that it be a good non-cryptographic hash; |
| 349 | * i.e. it not produce collisions when fed "random" data of the sort |
| 350 | * we expect to see. As long as the pool state differs for different |
| 351 | * inputs, we have preserved the input entropy and done a good job. |
| 352 | * The fact that an intelligent attacker can construct inputs that |
| 353 | * will produce controlled alterations to the pool's state is not |
| 354 | * important because we don't consider such inputs to contribute any |
| 355 | * randomness. The only property we need with respect to them is that |
| 356 | * the attacker can't increase his/her knowledge of the pool's state. |
| 357 | * Since all additions are reversible (knowing the final state and the |
| 358 | * input, you can reconstruct the initial state), if an attacker has |
| 359 | * any uncertainty about the initial state, he/she can only shuffle |
| 360 | * that uncertainty about, but never cause any collisions (which would |
| 361 | * decrease the uncertainty). |
| 362 | * |
| 363 | * The chosen system lets the state of the pool be (essentially) the input |
| 364 | * modulo the generator polymnomial. Now, for random primitive polynomials, |
| 365 | * this is a universal class of hash functions, meaning that the chance |
| 366 | * of a collision is limited by the attacker's knowledge of the generator |
| 367 | * polynomail, so if it is chosen at random, an attacker can never force |
| 368 | * a collision. Here, we use a fixed polynomial, but we *can* assume that |
| 369 | * ###--> it is unknown to the processes generating the input entropy. <-### |
| 370 | * Because of this important property, this is a good, collision-resistant |
| 371 | * hash; hash collisions will occur no more often than chance. |
| 372 | */ |
| 373 | |
| 374 | /* |
| 375 | * Static global variables |
| 376 | */ |
| 377 | static DECLARE_WAIT_QUEUE_HEAD(random_read_wait); |
| 378 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); |
| 379 | static struct fasync_struct *fasync; |
| 380 | |
| 381 | #if 0 |
| 382 | static int debug; |
| 383 | module_param(debug, bool, 0644); |
| 384 | #define DEBUG_ENT(fmt, arg...) do { \ |
| 385 | if (debug) \ |
| 386 | printk(KERN_DEBUG "random %04d %04d %04d: " \ |
| 387 | fmt,\ |
| 388 | input_pool.entropy_count,\ |
| 389 | blocking_pool.entropy_count,\ |
| 390 | nonblocking_pool.entropy_count,\ |
| 391 | ## arg); } while (0) |
| 392 | #else |
| 393 | #define DEBUG_ENT(fmt, arg...) do {} while (0) |
| 394 | #endif |
| 395 | |
| 396 | /********************************************************************** |
| 397 | * |
| 398 | * OS independent entropy store. Here are the functions which handle |
| 399 | * storing entropy in an entropy pool. |
| 400 | * |
| 401 | **********************************************************************/ |
| 402 | |
| 403 | struct entropy_store; |
| 404 | struct entropy_store { |
| 405 | /* read-only data: */ |
| 406 | struct poolinfo *poolinfo; |
| 407 | __u32 *pool; |
| 408 | const char *name; |
| 409 | int limit; |
| 410 | struct entropy_store *pull; |
| 411 | |
| 412 | /* read-write data: */ |
| 413 | spinlock_t lock; |
| 414 | unsigned add_ptr; |
| 415 | int entropy_count; |
| 416 | int input_rotate; |
| 417 | __u8 *last_data; |
| 418 | }; |
| 419 | |
| 420 | static __u32 input_pool_data[INPUT_POOL_WORDS]; |
| 421 | static __u32 blocking_pool_data[OUTPUT_POOL_WORDS]; |
| 422 | static __u32 nonblocking_pool_data[OUTPUT_POOL_WORDS]; |
| 423 | |
| 424 | static struct entropy_store input_pool = { |
| 425 | .poolinfo = &poolinfo_table[0], |
| 426 | .name = "input", |
| 427 | .limit = 1, |
| 428 | .lock = __SPIN_LOCK_UNLOCKED(&input_pool.lock), |
| 429 | .pool = input_pool_data |
| 430 | }; |
| 431 | |
| 432 | static struct entropy_store blocking_pool = { |
| 433 | .poolinfo = &poolinfo_table[1], |
| 434 | .name = "blocking", |
| 435 | .limit = 1, |
| 436 | .pull = &input_pool, |
| 437 | .lock = __SPIN_LOCK_UNLOCKED(&blocking_pool.lock), |
| 438 | .pool = blocking_pool_data |
| 439 | }; |
| 440 | |
| 441 | static struct entropy_store nonblocking_pool = { |
| 442 | .poolinfo = &poolinfo_table[1], |
| 443 | .name = "nonblocking", |
| 444 | .pull = &input_pool, |
| 445 | .lock = __SPIN_LOCK_UNLOCKED(&nonblocking_pool.lock), |
| 446 | .pool = nonblocking_pool_data |
| 447 | }; |
| 448 | |
| 449 | /* |
| 450 | * This function adds bytes into the entropy "pool". It does not |
| 451 | * update the entropy estimate. The caller should call |
| 452 | * credit_entropy_bits if this is appropriate. |
| 453 | * |
| 454 | * The pool is stirred with a primitive polynomial of the appropriate |
| 455 | * degree, and then twisted. We twist by three bits at a time because |
| 456 | * it's cheap to do so and helps slightly in the expected case where |
| 457 | * the entropy is concentrated in the low-order bits. |
| 458 | */ |
| 459 | static void mix_pool_bytes_extract(struct entropy_store *r, const void *in, |
| 460 | int nbytes, __u8 out[64]) |
| 461 | { |
| 462 | static __u32 const twist_table[8] = { |
| 463 | 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158, |
| 464 | 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; |
| 465 | unsigned long i, j, tap1, tap2, tap3, tap4, tap5; |
| 466 | int input_rotate; |
| 467 | int wordmask = r->poolinfo->poolwords - 1; |
| 468 | const char *bytes = in; |
| 469 | __u32 w; |
| 470 | unsigned long flags; |
| 471 | |
| 472 | /* Taps are constant, so we can load them without holding r->lock. */ |
| 473 | tap1 = r->poolinfo->tap1; |
| 474 | tap2 = r->poolinfo->tap2; |
| 475 | tap3 = r->poolinfo->tap3; |
| 476 | tap4 = r->poolinfo->tap4; |
| 477 | tap5 = r->poolinfo->tap5; |
| 478 | |
| 479 | spin_lock_irqsave(&r->lock, flags); |
| 480 | input_rotate = r->input_rotate; |
| 481 | i = r->add_ptr; |
| 482 | |
| 483 | /* mix one byte at a time to simplify size handling and churn faster */ |
| 484 | while (nbytes--) { |
| 485 | w = rol32(*bytes++, input_rotate & 31); |
| 486 | i = (i - 1) & wordmask; |
| 487 | |
| 488 | /* XOR in the various taps */ |
| 489 | w ^= r->pool[i]; |
| 490 | w ^= r->pool[(i + tap1) & wordmask]; |
| 491 | w ^= r->pool[(i + tap2) & wordmask]; |
| 492 | w ^= r->pool[(i + tap3) & wordmask]; |
| 493 | w ^= r->pool[(i + tap4) & wordmask]; |
| 494 | w ^= r->pool[(i + tap5) & wordmask]; |
| 495 | |
| 496 | /* Mix the result back in with a twist */ |
| 497 | r->pool[i] = (w >> 3) ^ twist_table[w & 7]; |
| 498 | |
| 499 | /* |
| 500 | * Normally, we add 7 bits of rotation to the pool. |
| 501 | * At the beginning of the pool, add an extra 7 bits |
| 502 | * rotation, so that successive passes spread the |
| 503 | * input bits across the pool evenly. |
| 504 | */ |
| 505 | input_rotate += i ? 7 : 14; |
| 506 | } |
| 507 | |
| 508 | r->input_rotate = input_rotate; |
| 509 | r->add_ptr = i; |
| 510 | |
| 511 | if (out) |
| 512 | for (j = 0; j < 16; j++) |
| 513 | ((__u32 *)out)[j] = r->pool[(i - j) & wordmask]; |
| 514 | |
| 515 | spin_unlock_irqrestore(&r->lock, flags); |
| 516 | } |
| 517 | |
| 518 | static void mix_pool_bytes(struct entropy_store *r, const void *in, int bytes) |
| 519 | { |
| 520 | mix_pool_bytes_extract(r, in, bytes, NULL); |
| 521 | } |
| 522 | |
| 523 | /* |
| 524 | * Credit (or debit) the entropy store with n bits of entropy |
| 525 | */ |
| 526 | static void credit_entropy_bits(struct entropy_store *r, int nbits) |
| 527 | { |
| 528 | unsigned long flags; |
| 529 | int entropy_count; |
| 530 | |
| 531 | if (!nbits) |
| 532 | return; |
| 533 | |
| 534 | spin_lock_irqsave(&r->lock, flags); |
| 535 | |
| 536 | DEBUG_ENT("added %d entropy credits to %s\n", nbits, r->name); |
| 537 | entropy_count = r->entropy_count; |
| 538 | entropy_count += nbits; |
| 539 | if (entropy_count < 0) { |
| 540 | DEBUG_ENT("negative entropy/overflow\n"); |
| 541 | entropy_count = 0; |
| 542 | } else if (entropy_count > r->poolinfo->POOLBITS) |
| 543 | entropy_count = r->poolinfo->POOLBITS; |
| 544 | r->entropy_count = entropy_count; |
| 545 | |
| 546 | /* should we wake readers? */ |
| 547 | if (r == &input_pool && entropy_count >= random_read_wakeup_thresh) { |
| 548 | wake_up_interruptible(&random_read_wait); |
| 549 | kill_fasync(&fasync, SIGIO, POLL_IN); |
| 550 | } |
| 551 | spin_unlock_irqrestore(&r->lock, flags); |
| 552 | } |
| 553 | |
| 554 | /********************************************************************* |
| 555 | * |
| 556 | * Entropy input management |
| 557 | * |
| 558 | *********************************************************************/ |
| 559 | |
| 560 | /* There is one of these per entropy source */ |
| 561 | struct timer_rand_state { |
| 562 | cycles_t last_time; |
| 563 | long last_delta, last_delta2; |
| 564 | unsigned dont_count_entropy:1; |
| 565 | }; |
| 566 | |
| 567 | #ifndef CONFIG_GENERIC_HARDIRQS |
| 568 | |
| 569 | static struct timer_rand_state *irq_timer_state[NR_IRQS]; |
| 570 | |
| 571 | static struct timer_rand_state *get_timer_rand_state(unsigned int irq) |
| 572 | { |
| 573 | return irq_timer_state[irq]; |
| 574 | } |
| 575 | |
| 576 | static void set_timer_rand_state(unsigned int irq, |
| 577 | struct timer_rand_state *state) |
| 578 | { |
| 579 | irq_timer_state[irq] = state; |
| 580 | } |
| 581 | |
| 582 | #else |
| 583 | |
| 584 | static struct timer_rand_state *get_timer_rand_state(unsigned int irq) |
| 585 | { |
| 586 | struct irq_desc *desc; |
| 587 | |
| 588 | desc = irq_to_desc(irq); |
| 589 | |
| 590 | return desc->timer_rand_state; |
| 591 | } |
| 592 | |
| 593 | static void set_timer_rand_state(unsigned int irq, |
| 594 | struct timer_rand_state *state) |
| 595 | { |
| 596 | struct irq_desc *desc; |
| 597 | |
| 598 | desc = irq_to_desc(irq); |
| 599 | |
| 600 | desc->timer_rand_state = state; |
| 601 | } |
| 602 | #endif |
| 603 | |
| 604 | static struct timer_rand_state input_timer_state; |
| 605 | |
| 606 | /* |
| 607 | * This function adds entropy to the entropy "pool" by using timing |
| 608 | * delays. It uses the timer_rand_state structure to make an estimate |
| 609 | * of how many bits of entropy this call has added to the pool. |
| 610 | * |
| 611 | * The number "num" is also added to the pool - it should somehow describe |
| 612 | * the type of event which just happened. This is currently 0-255 for |
| 613 | * keyboard scan codes, and 256 upwards for interrupts. |
| 614 | * |
| 615 | */ |
| 616 | static void add_timer_randomness(struct timer_rand_state *state, unsigned num) |
| 617 | { |
| 618 | struct { |
| 619 | cycles_t cycles; |
| 620 | long jiffies; |
| 621 | unsigned num; |
| 622 | } sample; |
| 623 | long delta, delta2, delta3; |
| 624 | |
| 625 | preempt_disable(); |
| 626 | /* if over the trickle threshold, use only 1 in 4096 samples */ |
| 627 | if (input_pool.entropy_count > trickle_thresh && |
| 628 | (__get_cpu_var(trickle_count)++ & 0xfff)) |
| 629 | goto out; |
| 630 | |
| 631 | sample.jiffies = jiffies; |
| 632 | sample.cycles = get_cycles(); |
| 633 | sample.num = num; |
| 634 | mix_pool_bytes(&input_pool, &sample, sizeof(sample)); |
| 635 | |
| 636 | /* |
| 637 | * Calculate number of bits of randomness we probably added. |
| 638 | * We take into account the first, second and third-order deltas |
| 639 | * in order to make our estimate. |
| 640 | */ |
| 641 | |
| 642 | if (!state->dont_count_entropy) { |
| 643 | delta = sample.jiffies - state->last_time; |
| 644 | state->last_time = sample.jiffies; |
| 645 | |
| 646 | delta2 = delta - state->last_delta; |
| 647 | state->last_delta = delta; |
| 648 | |
| 649 | delta3 = delta2 - state->last_delta2; |
| 650 | state->last_delta2 = delta2; |
| 651 | |
| 652 | if (delta < 0) |
| 653 | delta = -delta; |
| 654 | if (delta2 < 0) |
| 655 | delta2 = -delta2; |
| 656 | if (delta3 < 0) |
| 657 | delta3 = -delta3; |
| 658 | if (delta > delta2) |
| 659 | delta = delta2; |
| 660 | if (delta > delta3) |
| 661 | delta = delta3; |
| 662 | |
| 663 | /* |
| 664 | * delta is now minimum absolute delta. |
| 665 | * Round down by 1 bit on general principles, |
| 666 | * and limit entropy entimate to 12 bits. |
| 667 | */ |
| 668 | credit_entropy_bits(&input_pool, |
| 669 | min_t(int, fls(delta>>1), 11)); |
| 670 | } |
| 671 | out: |
| 672 | preempt_enable(); |
| 673 | } |
| 674 | |
| 675 | void add_input_randomness(unsigned int type, unsigned int code, |
| 676 | unsigned int value) |
| 677 | { |
| 678 | static unsigned char last_value; |
| 679 | |
| 680 | /* ignore autorepeat and the like */ |
| 681 | if (value == last_value) |
| 682 | return; |
| 683 | |
| 684 | DEBUG_ENT("input event\n"); |
| 685 | last_value = value; |
| 686 | add_timer_randomness(&input_timer_state, |
| 687 | (type << 4) ^ code ^ (code >> 4) ^ value); |
| 688 | } |
| 689 | EXPORT_SYMBOL_GPL(add_input_randomness); |
| 690 | |
| 691 | void add_interrupt_randomness(int irq) |
| 692 | { |
| 693 | struct timer_rand_state *state; |
| 694 | |
| 695 | state = get_timer_rand_state(irq); |
| 696 | |
| 697 | if (state == NULL) |
| 698 | return; |
| 699 | |
| 700 | DEBUG_ENT("irq event %d\n", irq); |
| 701 | add_timer_randomness(state, 0x100 + irq); |
| 702 | } |
| 703 | |
| 704 | #ifdef CONFIG_BLOCK |
| 705 | void add_disk_randomness(struct gendisk *disk) |
| 706 | { |
| 707 | if (!disk || !disk->random) |
| 708 | return; |
| 709 | /* first major is 1, so we get >= 0x200 here */ |
| 710 | DEBUG_ENT("disk event %d:%d\n", |
| 711 | MAJOR(disk_devt(disk)), MINOR(disk_devt(disk))); |
| 712 | |
| 713 | add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); |
| 714 | } |
| 715 | #endif |
| 716 | |
| 717 | #define EXTRACT_SIZE 10 |
| 718 | |
| 719 | /********************************************************************* |
| 720 | * |
| 721 | * Entropy extraction routines |
| 722 | * |
| 723 | *********************************************************************/ |
| 724 | |
| 725 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
| 726 | size_t nbytes, int min, int rsvd); |
| 727 | |
| 728 | /* |
| 729 | * This utility inline function is responsible for transfering entropy |
| 730 | * from the primary pool to the secondary extraction pool. We make |
| 731 | * sure we pull enough for a 'catastrophic reseed'. |
| 732 | */ |
| 733 | static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes) |
| 734 | { |
| 735 | __u32 tmp[OUTPUT_POOL_WORDS]; |
| 736 | |
| 737 | if (r->pull && r->entropy_count < nbytes * 8 && |
| 738 | r->entropy_count < r->poolinfo->POOLBITS) { |
| 739 | /* If we're limited, always leave two wakeup worth's BITS */ |
| 740 | int rsvd = r->limit ? 0 : random_read_wakeup_thresh/4; |
| 741 | int bytes = nbytes; |
| 742 | |
| 743 | /* pull at least as many as BYTES as wakeup BITS */ |
| 744 | bytes = max_t(int, bytes, random_read_wakeup_thresh / 8); |
| 745 | /* but never more than the buffer size */ |
| 746 | bytes = min_t(int, bytes, sizeof(tmp)); |
| 747 | |
| 748 | DEBUG_ENT("going to reseed %s with %d bits " |
| 749 | "(%d of %d requested)\n", |
| 750 | r->name, bytes * 8, nbytes * 8, r->entropy_count); |
| 751 | |
| 752 | bytes = extract_entropy(r->pull, tmp, bytes, |
| 753 | random_read_wakeup_thresh / 8, rsvd); |
| 754 | mix_pool_bytes(r, tmp, bytes); |
| 755 | credit_entropy_bits(r, bytes*8); |
| 756 | } |
| 757 | } |
| 758 | |
| 759 | /* |
| 760 | * These functions extracts randomness from the "entropy pool", and |
| 761 | * returns it in a buffer. |
| 762 | * |
| 763 | * The min parameter specifies the minimum amount we can pull before |
| 764 | * failing to avoid races that defeat catastrophic reseeding while the |
| 765 | * reserved parameter indicates how much entropy we must leave in the |
| 766 | * pool after each pull to avoid starving other readers. |
| 767 | * |
| 768 | * Note: extract_entropy() assumes that .poolwords is a multiple of 16 words. |
| 769 | */ |
| 770 | |
| 771 | static size_t account(struct entropy_store *r, size_t nbytes, int min, |
| 772 | int reserved) |
| 773 | { |
| 774 | unsigned long flags; |
| 775 | |
| 776 | /* Hold lock while accounting */ |
| 777 | spin_lock_irqsave(&r->lock, flags); |
| 778 | |
| 779 | BUG_ON(r->entropy_count > r->poolinfo->POOLBITS); |
| 780 | DEBUG_ENT("trying to extract %d bits from %s\n", |
| 781 | nbytes * 8, r->name); |
| 782 | |
| 783 | /* Can we pull enough? */ |
| 784 | if (r->entropy_count / 8 < min + reserved) { |
| 785 | nbytes = 0; |
| 786 | } else { |
| 787 | /* If limited, never pull more than available */ |
| 788 | if (r->limit && nbytes + reserved >= r->entropy_count / 8) |
| 789 | nbytes = r->entropy_count/8 - reserved; |
| 790 | |
| 791 | if (r->entropy_count / 8 >= nbytes + reserved) |
| 792 | r->entropy_count -= nbytes*8; |
| 793 | else |
| 794 | r->entropy_count = reserved; |
| 795 | |
| 796 | if (r->entropy_count < random_write_wakeup_thresh) { |
| 797 | wake_up_interruptible(&random_write_wait); |
| 798 | kill_fasync(&fasync, SIGIO, POLL_OUT); |
| 799 | } |
| 800 | } |
| 801 | |
| 802 | DEBUG_ENT("debiting %d entropy credits from %s%s\n", |
| 803 | nbytes * 8, r->name, r->limit ? "" : " (unlimited)"); |
| 804 | |
| 805 | spin_unlock_irqrestore(&r->lock, flags); |
| 806 | |
| 807 | return nbytes; |
| 808 | } |
| 809 | |
| 810 | static void extract_buf(struct entropy_store *r, __u8 *out) |
| 811 | { |
| 812 | int i; |
| 813 | __u32 hash[5], workspace[SHA_WORKSPACE_WORDS]; |
| 814 | __u8 extract[64]; |
| 815 | |
| 816 | /* Generate a hash across the pool, 16 words (512 bits) at a time */ |
| 817 | sha_init(hash); |
| 818 | for (i = 0; i < r->poolinfo->poolwords; i += 16) |
| 819 | sha_transform(hash, (__u8 *)(r->pool + i), workspace); |
| 820 | |
| 821 | /* |
| 822 | * We mix the hash back into the pool to prevent backtracking |
| 823 | * attacks (where the attacker knows the state of the pool |
| 824 | * plus the current outputs, and attempts to find previous |
| 825 | * ouputs), unless the hash function can be inverted. By |
| 826 | * mixing at least a SHA1 worth of hash data back, we make |
| 827 | * brute-forcing the feedback as hard as brute-forcing the |
| 828 | * hash. |
| 829 | */ |
| 830 | mix_pool_bytes_extract(r, hash, sizeof(hash), extract); |
| 831 | |
| 832 | /* |
| 833 | * To avoid duplicates, we atomically extract a portion of the |
| 834 | * pool while mixing, and hash one final time. |
| 835 | */ |
| 836 | sha_transform(hash, extract, workspace); |
| 837 | memset(extract, 0, sizeof(extract)); |
| 838 | memset(workspace, 0, sizeof(workspace)); |
| 839 | |
| 840 | /* |
| 841 | * In case the hash function has some recognizable output |
| 842 | * pattern, we fold it in half. Thus, we always feed back |
| 843 | * twice as much data as we output. |
| 844 | */ |
| 845 | hash[0] ^= hash[3]; |
| 846 | hash[1] ^= hash[4]; |
| 847 | hash[2] ^= rol32(hash[2], 16); |
| 848 | memcpy(out, hash, EXTRACT_SIZE); |
| 849 | memset(hash, 0, sizeof(hash)); |
| 850 | } |
| 851 | |
| 852 | static ssize_t extract_entropy(struct entropy_store *r, void *buf, |
| 853 | size_t nbytes, int min, int reserved) |
| 854 | { |
| 855 | ssize_t ret = 0, i; |
| 856 | __u8 tmp[EXTRACT_SIZE]; |
| 857 | unsigned long flags; |
| 858 | |
| 859 | xfer_secondary_pool(r, nbytes); |
| 860 | nbytes = account(r, nbytes, min, reserved); |
| 861 | |
| 862 | while (nbytes) { |
| 863 | extract_buf(r, tmp); |
| 864 | |
| 865 | if (r->last_data) { |
| 866 | spin_lock_irqsave(&r->lock, flags); |
| 867 | if (!memcmp(tmp, r->last_data, EXTRACT_SIZE)) |
| 868 | panic("Hardware RNG duplicated output!\n"); |
| 869 | memcpy(r->last_data, tmp, EXTRACT_SIZE); |
| 870 | spin_unlock_irqrestore(&r->lock, flags); |
| 871 | } |
| 872 | i = min_t(int, nbytes, EXTRACT_SIZE); |
| 873 | memcpy(buf, tmp, i); |
| 874 | nbytes -= i; |
| 875 | buf += i; |
| 876 | ret += i; |
| 877 | } |
| 878 | |
| 879 | /* Wipe data just returned from memory */ |
| 880 | memset(tmp, 0, sizeof(tmp)); |
| 881 | |
| 882 | return ret; |
| 883 | } |
| 884 | |
| 885 | static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf, |
| 886 | size_t nbytes) |
| 887 | { |
| 888 | ssize_t ret = 0, i; |
| 889 | __u8 tmp[EXTRACT_SIZE]; |
| 890 | |
| 891 | xfer_secondary_pool(r, nbytes); |
| 892 | nbytes = account(r, nbytes, 0, 0); |
| 893 | |
| 894 | while (nbytes) { |
| 895 | if (need_resched()) { |
| 896 | if (signal_pending(current)) { |
| 897 | if (ret == 0) |
| 898 | ret = -ERESTARTSYS; |
| 899 | break; |
| 900 | } |
| 901 | schedule(); |
| 902 | } |
| 903 | |
| 904 | extract_buf(r, tmp); |
| 905 | i = min_t(int, nbytes, EXTRACT_SIZE); |
| 906 | if (copy_to_user(buf, tmp, i)) { |
| 907 | ret = -EFAULT; |
| 908 | break; |
| 909 | } |
| 910 | |
| 911 | nbytes -= i; |
| 912 | buf += i; |
| 913 | ret += i; |
| 914 | } |
| 915 | |
| 916 | /* Wipe data just returned from memory */ |
| 917 | memset(tmp, 0, sizeof(tmp)); |
| 918 | |
| 919 | return ret; |
| 920 | } |
| 921 | |
| 922 | /* |
| 923 | * This function is the exported kernel interface. It returns some |
| 924 | * number of good random numbers, suitable for seeding TCP sequence |
| 925 | * numbers, etc. |
| 926 | */ |
| 927 | void get_random_bytes(void *buf, int nbytes) |
| 928 | { |
| 929 | extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0); |
| 930 | } |
| 931 | EXPORT_SYMBOL(get_random_bytes); |
| 932 | |
| 933 | /* |
| 934 | * init_std_data - initialize pool with system data |
| 935 | * |
| 936 | * @r: pool to initialize |
| 937 | * |
| 938 | * This function clears the pool's entropy count and mixes some system |
| 939 | * data into the pool to prepare it for use. The pool is not cleared |
| 940 | * as that can only decrease the entropy in the pool. |
| 941 | */ |
| 942 | static void init_std_data(struct entropy_store *r) |
| 943 | { |
| 944 | ktime_t now; |
| 945 | unsigned long flags; |
| 946 | |
| 947 | spin_lock_irqsave(&r->lock, flags); |
| 948 | r->entropy_count = 0; |
| 949 | spin_unlock_irqrestore(&r->lock, flags); |
| 950 | |
| 951 | now = ktime_get_real(); |
| 952 | mix_pool_bytes(r, &now, sizeof(now)); |
| 953 | mix_pool_bytes(r, utsname(), sizeof(*(utsname()))); |
| 954 | /* Enable continuous test in fips mode */ |
| 955 | if (fips_enabled) |
| 956 | r->last_data = kmalloc(EXTRACT_SIZE, GFP_KERNEL); |
| 957 | } |
| 958 | |
| 959 | static int rand_initialize(void) |
| 960 | { |
| 961 | init_std_data(&input_pool); |
| 962 | init_std_data(&blocking_pool); |
| 963 | init_std_data(&nonblocking_pool); |
| 964 | return 0; |
| 965 | } |
| 966 | module_init(rand_initialize); |
| 967 | |
| 968 | void rand_initialize_irq(int irq) |
| 969 | { |
| 970 | struct timer_rand_state *state; |
| 971 | |
| 972 | state = get_timer_rand_state(irq); |
| 973 | |
| 974 | if (state) |
| 975 | return; |
| 976 | |
| 977 | /* |
| 978 | * If kzalloc returns null, we just won't use that entropy |
| 979 | * source. |
| 980 | */ |
| 981 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
| 982 | if (state) |
| 983 | set_timer_rand_state(irq, state); |
| 984 | } |
| 985 | |
| 986 | #ifdef CONFIG_BLOCK |
| 987 | void rand_initialize_disk(struct gendisk *disk) |
| 988 | { |
| 989 | struct timer_rand_state *state; |
| 990 | |
| 991 | /* |
| 992 | * If kzalloc returns null, we just won't use that entropy |
| 993 | * source. |
| 994 | */ |
| 995 | state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); |
| 996 | if (state) |
| 997 | disk->random = state; |
| 998 | } |
| 999 | #endif |
| 1000 | |
| 1001 | static ssize_t |
| 1002 | random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
| 1003 | { |
| 1004 | ssize_t n, retval = 0, count = 0; |
| 1005 | |
| 1006 | if (nbytes == 0) |
| 1007 | return 0; |
| 1008 | |
| 1009 | while (nbytes > 0) { |
| 1010 | n = nbytes; |
| 1011 | if (n > SEC_XFER_SIZE) |
| 1012 | n = SEC_XFER_SIZE; |
| 1013 | |
| 1014 | DEBUG_ENT("reading %d bits\n", n*8); |
| 1015 | |
| 1016 | n = extract_entropy_user(&blocking_pool, buf, n); |
| 1017 | |
| 1018 | DEBUG_ENT("read got %d bits (%d still needed)\n", |
| 1019 | n*8, (nbytes-n)*8); |
| 1020 | |
| 1021 | if (n == 0) { |
| 1022 | if (file->f_flags & O_NONBLOCK) { |
| 1023 | retval = -EAGAIN; |
| 1024 | break; |
| 1025 | } |
| 1026 | |
| 1027 | DEBUG_ENT("sleeping?\n"); |
| 1028 | |
| 1029 | wait_event_interruptible(random_read_wait, |
| 1030 | input_pool.entropy_count >= |
| 1031 | random_read_wakeup_thresh); |
| 1032 | |
| 1033 | DEBUG_ENT("awake\n"); |
| 1034 | |
| 1035 | if (signal_pending(current)) { |
| 1036 | retval = -ERESTARTSYS; |
| 1037 | break; |
| 1038 | } |
| 1039 | |
| 1040 | continue; |
| 1041 | } |
| 1042 | |
| 1043 | if (n < 0) { |
| 1044 | retval = n; |
| 1045 | break; |
| 1046 | } |
| 1047 | count += n; |
| 1048 | buf += n; |
| 1049 | nbytes -= n; |
| 1050 | break; /* This break makes the device work */ |
| 1051 | /* like a named pipe */ |
| 1052 | } |
| 1053 | |
| 1054 | /* |
| 1055 | * If we gave the user some bytes, update the access time. |
| 1056 | */ |
| 1057 | if (count) |
| 1058 | file_accessed(file); |
| 1059 | |
| 1060 | return (count ? count : retval); |
| 1061 | } |
| 1062 | |
| 1063 | static ssize_t |
| 1064 | urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
| 1065 | { |
| 1066 | return extract_entropy_user(&nonblocking_pool, buf, nbytes); |
| 1067 | } |
| 1068 | |
| 1069 | static unsigned int |
| 1070 | random_poll(struct file *file, poll_table * wait) |
| 1071 | { |
| 1072 | unsigned int mask; |
| 1073 | |
| 1074 | poll_wait(file, &random_read_wait, wait); |
| 1075 | poll_wait(file, &random_write_wait, wait); |
| 1076 | mask = 0; |
| 1077 | if (input_pool.entropy_count >= random_read_wakeup_thresh) |
| 1078 | mask |= POLLIN | POLLRDNORM; |
| 1079 | if (input_pool.entropy_count < random_write_wakeup_thresh) |
| 1080 | mask |= POLLOUT | POLLWRNORM; |
| 1081 | return mask; |
| 1082 | } |
| 1083 | |
| 1084 | static int |
| 1085 | write_pool(struct entropy_store *r, const char __user *buffer, size_t count) |
| 1086 | { |
| 1087 | size_t bytes; |
| 1088 | __u32 buf[16]; |
| 1089 | const char __user *p = buffer; |
| 1090 | |
| 1091 | while (count > 0) { |
| 1092 | bytes = min(count, sizeof(buf)); |
| 1093 | if (copy_from_user(&buf, p, bytes)) |
| 1094 | return -EFAULT; |
| 1095 | |
| 1096 | count -= bytes; |
| 1097 | p += bytes; |
| 1098 | |
| 1099 | mix_pool_bytes(r, buf, bytes); |
| 1100 | cond_resched(); |
| 1101 | } |
| 1102 | |
| 1103 | return 0; |
| 1104 | } |
| 1105 | |
| 1106 | static ssize_t random_write(struct file *file, const char __user *buffer, |
| 1107 | size_t count, loff_t *ppos) |
| 1108 | { |
| 1109 | size_t ret; |
| 1110 | struct inode *inode = file->f_path.dentry->d_inode; |
| 1111 | |
| 1112 | ret = write_pool(&blocking_pool, buffer, count); |
| 1113 | if (ret) |
| 1114 | return ret; |
| 1115 | ret = write_pool(&nonblocking_pool, buffer, count); |
| 1116 | if (ret) |
| 1117 | return ret; |
| 1118 | |
| 1119 | inode->i_mtime = current_fs_time(inode->i_sb); |
| 1120 | mark_inode_dirty(inode); |
| 1121 | return (ssize_t)count; |
| 1122 | } |
| 1123 | |
| 1124 | static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) |
| 1125 | { |
| 1126 | int size, ent_count; |
| 1127 | int __user *p = (int __user *)arg; |
| 1128 | int retval; |
| 1129 | |
| 1130 | switch (cmd) { |
| 1131 | case RNDGETENTCNT: |
| 1132 | /* inherently racy, no point locking */ |
| 1133 | if (put_user(input_pool.entropy_count, p)) |
| 1134 | return -EFAULT; |
| 1135 | return 0; |
| 1136 | case RNDADDTOENTCNT: |
| 1137 | if (!capable(CAP_SYS_ADMIN)) |
| 1138 | return -EPERM; |
| 1139 | if (get_user(ent_count, p)) |
| 1140 | return -EFAULT; |
| 1141 | credit_entropy_bits(&input_pool, ent_count); |
| 1142 | return 0; |
| 1143 | case RNDADDENTROPY: |
| 1144 | if (!capable(CAP_SYS_ADMIN)) |
| 1145 | return -EPERM; |
| 1146 | if (get_user(ent_count, p++)) |
| 1147 | return -EFAULT; |
| 1148 | if (ent_count < 0) |
| 1149 | return -EINVAL; |
| 1150 | if (get_user(size, p++)) |
| 1151 | return -EFAULT; |
| 1152 | retval = write_pool(&input_pool, (const char __user *)p, |
| 1153 | size); |
| 1154 | if (retval < 0) |
| 1155 | return retval; |
| 1156 | credit_entropy_bits(&input_pool, ent_count); |
| 1157 | return 0; |
| 1158 | case RNDZAPENTCNT: |
| 1159 | case RNDCLEARPOOL: |
| 1160 | /* Clear the entropy pool counters. */ |
| 1161 | if (!capable(CAP_SYS_ADMIN)) |
| 1162 | return -EPERM; |
| 1163 | rand_initialize(); |
| 1164 | return 0; |
| 1165 | default: |
| 1166 | return -EINVAL; |
| 1167 | } |
| 1168 | } |
| 1169 | |
| 1170 | static int random_fasync(int fd, struct file *filp, int on) |
| 1171 | { |
| 1172 | return fasync_helper(fd, filp, on, &fasync); |
| 1173 | } |
| 1174 | |
| 1175 | const struct file_operations random_fops = { |
| 1176 | .read = random_read, |
| 1177 | .write = random_write, |
| 1178 | .poll = random_poll, |
| 1179 | .unlocked_ioctl = random_ioctl, |
| 1180 | .fasync = random_fasync, |
| 1181 | }; |
| 1182 | |
| 1183 | const struct file_operations urandom_fops = { |
| 1184 | .read = urandom_read, |
| 1185 | .write = random_write, |
| 1186 | .unlocked_ioctl = random_ioctl, |
| 1187 | .fasync = random_fasync, |
| 1188 | }; |
| 1189 | |
| 1190 | /*************************************************************** |
| 1191 | * Random UUID interface |
| 1192 | * |
| 1193 | * Used here for a Boot ID, but can be useful for other kernel |
| 1194 | * drivers. |
| 1195 | ***************************************************************/ |
| 1196 | |
| 1197 | /* |
| 1198 | * Generate random UUID |
| 1199 | */ |
| 1200 | void generate_random_uuid(unsigned char uuid_out[16]) |
| 1201 | { |
| 1202 | get_random_bytes(uuid_out, 16); |
| 1203 | /* Set UUID version to 4 --- truely random generation */ |
| 1204 | uuid_out[6] = (uuid_out[6] & 0x0F) | 0x40; |
| 1205 | /* Set the UUID variant to DCE */ |
| 1206 | uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80; |
| 1207 | } |
| 1208 | EXPORT_SYMBOL(generate_random_uuid); |
| 1209 | |
| 1210 | /******************************************************************** |
| 1211 | * |
| 1212 | * Sysctl interface |
| 1213 | * |
| 1214 | ********************************************************************/ |
| 1215 | |
| 1216 | #ifdef CONFIG_SYSCTL |
| 1217 | |
| 1218 | #include <linux/sysctl.h> |
| 1219 | |
| 1220 | static int min_read_thresh = 8, min_write_thresh; |
| 1221 | static int max_read_thresh = INPUT_POOL_WORDS * 32; |
| 1222 | static int max_write_thresh = INPUT_POOL_WORDS * 32; |
| 1223 | static char sysctl_bootid[16]; |
| 1224 | |
| 1225 | /* |
| 1226 | * These functions is used to return both the bootid UUID, and random |
| 1227 | * UUID. The difference is in whether table->data is NULL; if it is, |
| 1228 | * then a new UUID is generated and returned to the user. |
| 1229 | * |
| 1230 | * If the user accesses this via the proc interface, it will be returned |
| 1231 | * as an ASCII string in the standard UUID format. If accesses via the |
| 1232 | * sysctl system call, it is returned as 16 bytes of binary data. |
| 1233 | */ |
| 1234 | static int proc_do_uuid(ctl_table *table, int write, struct file *filp, |
| 1235 | void __user *buffer, size_t *lenp, loff_t *ppos) |
| 1236 | { |
| 1237 | ctl_table fake_table; |
| 1238 | unsigned char buf[64], tmp_uuid[16], *uuid; |
| 1239 | |
| 1240 | uuid = table->data; |
| 1241 | if (!uuid) { |
| 1242 | uuid = tmp_uuid; |
| 1243 | uuid[8] = 0; |
| 1244 | } |
| 1245 | if (uuid[8] == 0) |
| 1246 | generate_random_uuid(uuid); |
| 1247 | |
| 1248 | sprintf(buf, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-" |
| 1249 | "%02x%02x%02x%02x%02x%02x", |
| 1250 | uuid[0], uuid[1], uuid[2], uuid[3], |
| 1251 | uuid[4], uuid[5], uuid[6], uuid[7], |
| 1252 | uuid[8], uuid[9], uuid[10], uuid[11], |
| 1253 | uuid[12], uuid[13], uuid[14], uuid[15]); |
| 1254 | fake_table.data = buf; |
| 1255 | fake_table.maxlen = sizeof(buf); |
| 1256 | |
| 1257 | return proc_dostring(&fake_table, write, filp, buffer, lenp, ppos); |
| 1258 | } |
| 1259 | |
| 1260 | static int uuid_strategy(ctl_table *table, |
| 1261 | void __user *oldval, size_t __user *oldlenp, |
| 1262 | void __user *newval, size_t newlen) |
| 1263 | { |
| 1264 | unsigned char tmp_uuid[16], *uuid; |
| 1265 | unsigned int len; |
| 1266 | |
| 1267 | if (!oldval || !oldlenp) |
| 1268 | return 1; |
| 1269 | |
| 1270 | uuid = table->data; |
| 1271 | if (!uuid) { |
| 1272 | uuid = tmp_uuid; |
| 1273 | uuid[8] = 0; |
| 1274 | } |
| 1275 | if (uuid[8] == 0) |
| 1276 | generate_random_uuid(uuid); |
| 1277 | |
| 1278 | if (get_user(len, oldlenp)) |
| 1279 | return -EFAULT; |
| 1280 | if (len) { |
| 1281 | if (len > 16) |
| 1282 | len = 16; |
| 1283 | if (copy_to_user(oldval, uuid, len) || |
| 1284 | put_user(len, oldlenp)) |
| 1285 | return -EFAULT; |
| 1286 | } |
| 1287 | return 1; |
| 1288 | } |
| 1289 | |
| 1290 | static int sysctl_poolsize = INPUT_POOL_WORDS * 32; |
| 1291 | ctl_table random_table[] = { |
| 1292 | { |
| 1293 | .ctl_name = RANDOM_POOLSIZE, |
| 1294 | .procname = "poolsize", |
| 1295 | .data = &sysctl_poolsize, |
| 1296 | .maxlen = sizeof(int), |
| 1297 | .mode = 0444, |
| 1298 | .proc_handler = &proc_dointvec, |
| 1299 | }, |
| 1300 | { |
| 1301 | .ctl_name = RANDOM_ENTROPY_COUNT, |
| 1302 | .procname = "entropy_avail", |
| 1303 | .maxlen = sizeof(int), |
| 1304 | .mode = 0444, |
| 1305 | .proc_handler = &proc_dointvec, |
| 1306 | .data = &input_pool.entropy_count, |
| 1307 | }, |
| 1308 | { |
| 1309 | .ctl_name = RANDOM_READ_THRESH, |
| 1310 | .procname = "read_wakeup_threshold", |
| 1311 | .data = &random_read_wakeup_thresh, |
| 1312 | .maxlen = sizeof(int), |
| 1313 | .mode = 0644, |
| 1314 | .proc_handler = &proc_dointvec_minmax, |
| 1315 | .strategy = &sysctl_intvec, |
| 1316 | .extra1 = &min_read_thresh, |
| 1317 | .extra2 = &max_read_thresh, |
| 1318 | }, |
| 1319 | { |
| 1320 | .ctl_name = RANDOM_WRITE_THRESH, |
| 1321 | .procname = "write_wakeup_threshold", |
| 1322 | .data = &random_write_wakeup_thresh, |
| 1323 | .maxlen = sizeof(int), |
| 1324 | .mode = 0644, |
| 1325 | .proc_handler = &proc_dointvec_minmax, |
| 1326 | .strategy = &sysctl_intvec, |
| 1327 | .extra1 = &min_write_thresh, |
| 1328 | .extra2 = &max_write_thresh, |
| 1329 | }, |
| 1330 | { |
| 1331 | .ctl_name = RANDOM_BOOT_ID, |
| 1332 | .procname = "boot_id", |
| 1333 | .data = &sysctl_bootid, |
| 1334 | .maxlen = 16, |
| 1335 | .mode = 0444, |
| 1336 | .proc_handler = &proc_do_uuid, |
| 1337 | .strategy = &uuid_strategy, |
| 1338 | }, |
| 1339 | { |
| 1340 | .ctl_name = RANDOM_UUID, |
| 1341 | .procname = "uuid", |
| 1342 | .maxlen = 16, |
| 1343 | .mode = 0444, |
| 1344 | .proc_handler = &proc_do_uuid, |
| 1345 | .strategy = &uuid_strategy, |
| 1346 | }, |
| 1347 | { .ctl_name = 0 } |
| 1348 | }; |
| 1349 | #endif /* CONFIG_SYSCTL */ |
| 1350 | |
| 1351 | /******************************************************************** |
| 1352 | * |
| 1353 | * Random funtions for networking |
| 1354 | * |
| 1355 | ********************************************************************/ |
| 1356 | |
| 1357 | /* |
| 1358 | * TCP initial sequence number picking. This uses the random number |
| 1359 | * generator to pick an initial secret value. This value is hashed |
| 1360 | * along with the TCP endpoint information to provide a unique |
| 1361 | * starting point for each pair of TCP endpoints. This defeats |
| 1362 | * attacks which rely on guessing the initial TCP sequence number. |
| 1363 | * This algorithm was suggested by Steve Bellovin. |
| 1364 | * |
| 1365 | * Using a very strong hash was taking an appreciable amount of the total |
| 1366 | * TCP connection establishment time, so this is a weaker hash, |
| 1367 | * compensated for by changing the secret periodically. |
| 1368 | */ |
| 1369 | |
| 1370 | /* F, G and H are basic MD4 functions: selection, majority, parity */ |
| 1371 | #define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z)))) |
| 1372 | #define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z))) |
| 1373 | #define H(x, y, z) ((x) ^ (y) ^ (z)) |
| 1374 | |
| 1375 | /* |
| 1376 | * The generic round function. The application is so specific that |
| 1377 | * we don't bother protecting all the arguments with parens, as is generally |
| 1378 | * good macro practice, in favor of extra legibility. |
| 1379 | * Rotation is separate from addition to prevent recomputation |
| 1380 | */ |
| 1381 | #define ROUND(f, a, b, c, d, x, s) \ |
| 1382 | (a += f(b, c, d) + x, a = (a << s) | (a >> (32 - s))) |
| 1383 | #define K1 0 |
| 1384 | #define K2 013240474631UL |
| 1385 | #define K3 015666365641UL |
| 1386 | |
| 1387 | #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) |
| 1388 | |
| 1389 | static __u32 twothirdsMD4Transform(__u32 const buf[4], __u32 const in[12]) |
| 1390 | { |
| 1391 | __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3]; |
| 1392 | |
| 1393 | /* Round 1 */ |
| 1394 | ROUND(F, a, b, c, d, in[ 0] + K1, 3); |
| 1395 | ROUND(F, d, a, b, c, in[ 1] + K1, 7); |
| 1396 | ROUND(F, c, d, a, b, in[ 2] + K1, 11); |
| 1397 | ROUND(F, b, c, d, a, in[ 3] + K1, 19); |
| 1398 | ROUND(F, a, b, c, d, in[ 4] + K1, 3); |
| 1399 | ROUND(F, d, a, b, c, in[ 5] + K1, 7); |
| 1400 | ROUND(F, c, d, a, b, in[ 6] + K1, 11); |
| 1401 | ROUND(F, b, c, d, a, in[ 7] + K1, 19); |
| 1402 | ROUND(F, a, b, c, d, in[ 8] + K1, 3); |
| 1403 | ROUND(F, d, a, b, c, in[ 9] + K1, 7); |
| 1404 | ROUND(F, c, d, a, b, in[10] + K1, 11); |
| 1405 | ROUND(F, b, c, d, a, in[11] + K1, 19); |
| 1406 | |
| 1407 | /* Round 2 */ |
| 1408 | ROUND(G, a, b, c, d, in[ 1] + K2, 3); |
| 1409 | ROUND(G, d, a, b, c, in[ 3] + K2, 5); |
| 1410 | ROUND(G, c, d, a, b, in[ 5] + K2, 9); |
| 1411 | ROUND(G, b, c, d, a, in[ 7] + K2, 13); |
| 1412 | ROUND(G, a, b, c, d, in[ 9] + K2, 3); |
| 1413 | ROUND(G, d, a, b, c, in[11] + K2, 5); |
| 1414 | ROUND(G, c, d, a, b, in[ 0] + K2, 9); |
| 1415 | ROUND(G, b, c, d, a, in[ 2] + K2, 13); |
| 1416 | ROUND(G, a, b, c, d, in[ 4] + K2, 3); |
| 1417 | ROUND(G, d, a, b, c, in[ 6] + K2, 5); |
| 1418 | ROUND(G, c, d, a, b, in[ 8] + K2, 9); |
| 1419 | ROUND(G, b, c, d, a, in[10] + K2, 13); |
| 1420 | |
| 1421 | /* Round 3 */ |
| 1422 | ROUND(H, a, b, c, d, in[ 3] + K3, 3); |
| 1423 | ROUND(H, d, a, b, c, in[ 7] + K3, 9); |
| 1424 | ROUND(H, c, d, a, b, in[11] + K3, 11); |
| 1425 | ROUND(H, b, c, d, a, in[ 2] + K3, 15); |
| 1426 | ROUND(H, a, b, c, d, in[ 6] + K3, 3); |
| 1427 | ROUND(H, d, a, b, c, in[10] + K3, 9); |
| 1428 | ROUND(H, c, d, a, b, in[ 1] + K3, 11); |
| 1429 | ROUND(H, b, c, d, a, in[ 5] + K3, 15); |
| 1430 | ROUND(H, a, b, c, d, in[ 9] + K3, 3); |
| 1431 | ROUND(H, d, a, b, c, in[ 0] + K3, 9); |
| 1432 | ROUND(H, c, d, a, b, in[ 4] + K3, 11); |
| 1433 | ROUND(H, b, c, d, a, in[ 8] + K3, 15); |
| 1434 | |
| 1435 | return buf[1] + b; /* "most hashed" word */ |
| 1436 | /* Alternative: return sum of all words? */ |
| 1437 | } |
| 1438 | #endif |
| 1439 | |
| 1440 | #undef ROUND |
| 1441 | #undef F |
| 1442 | #undef G |
| 1443 | #undef H |
| 1444 | #undef K1 |
| 1445 | #undef K2 |
| 1446 | #undef K3 |
| 1447 | |
| 1448 | /* This should not be decreased so low that ISNs wrap too fast. */ |
| 1449 | #define REKEY_INTERVAL (300 * HZ) |
| 1450 | /* |
| 1451 | * Bit layout of the tcp sequence numbers (before adding current time): |
| 1452 | * bit 24-31: increased after every key exchange |
| 1453 | * bit 0-23: hash(source,dest) |
| 1454 | * |
| 1455 | * The implementation is similar to the algorithm described |
| 1456 | * in the Appendix of RFC 1185, except that |
| 1457 | * - it uses a 1 MHz clock instead of a 250 kHz clock |
| 1458 | * - it performs a rekey every 5 minutes, which is equivalent |
| 1459 | * to a (source,dest) tulple dependent forward jump of the |
| 1460 | * clock by 0..2^(HASH_BITS+1) |
| 1461 | * |
| 1462 | * Thus the average ISN wraparound time is 68 minutes instead of |
| 1463 | * 4.55 hours. |
| 1464 | * |
| 1465 | * SMP cleanup and lock avoidance with poor man's RCU. |
| 1466 | * Manfred Spraul <manfred@colorfullife.com> |
| 1467 | * |
| 1468 | */ |
| 1469 | #define COUNT_BITS 8 |
| 1470 | #define COUNT_MASK ((1 << COUNT_BITS) - 1) |
| 1471 | #define HASH_BITS 24 |
| 1472 | #define HASH_MASK ((1 << HASH_BITS) - 1) |
| 1473 | |
| 1474 | static struct keydata { |
| 1475 | __u32 count; /* already shifted to the final position */ |
| 1476 | __u32 secret[12]; |
| 1477 | } ____cacheline_aligned ip_keydata[2]; |
| 1478 | |
| 1479 | static unsigned int ip_cnt; |
| 1480 | |
| 1481 | static void rekey_seq_generator(struct work_struct *work); |
| 1482 | |
| 1483 | static DECLARE_DELAYED_WORK(rekey_work, rekey_seq_generator); |
| 1484 | |
| 1485 | /* |
| 1486 | * Lock avoidance: |
| 1487 | * The ISN generation runs lockless - it's just a hash over random data. |
| 1488 | * State changes happen every 5 minutes when the random key is replaced. |
| 1489 | * Synchronization is performed by having two copies of the hash function |
| 1490 | * state and rekey_seq_generator always updates the inactive copy. |
| 1491 | * The copy is then activated by updating ip_cnt. |
| 1492 | * The implementation breaks down if someone blocks the thread |
| 1493 | * that processes SYN requests for more than 5 minutes. Should never |
| 1494 | * happen, and even if that happens only a not perfectly compliant |
| 1495 | * ISN is generated, nothing fatal. |
| 1496 | */ |
| 1497 | static void rekey_seq_generator(struct work_struct *work) |
| 1498 | { |
| 1499 | struct keydata *keyptr = &ip_keydata[1 ^ (ip_cnt & 1)]; |
| 1500 | |
| 1501 | get_random_bytes(keyptr->secret, sizeof(keyptr->secret)); |
| 1502 | keyptr->count = (ip_cnt & COUNT_MASK) << HASH_BITS; |
| 1503 | smp_wmb(); |
| 1504 | ip_cnt++; |
| 1505 | schedule_delayed_work(&rekey_work, |
| 1506 | round_jiffies_relative(REKEY_INTERVAL)); |
| 1507 | } |
| 1508 | |
| 1509 | static inline struct keydata *get_keyptr(void) |
| 1510 | { |
| 1511 | struct keydata *keyptr = &ip_keydata[ip_cnt & 1]; |
| 1512 | |
| 1513 | smp_rmb(); |
| 1514 | |
| 1515 | return keyptr; |
| 1516 | } |
| 1517 | |
| 1518 | static __init int seqgen_init(void) |
| 1519 | { |
| 1520 | rekey_seq_generator(NULL); |
| 1521 | return 0; |
| 1522 | } |
| 1523 | late_initcall(seqgen_init); |
| 1524 | |
| 1525 | #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) |
| 1526 | __u32 secure_tcpv6_sequence_number(__be32 *saddr, __be32 *daddr, |
| 1527 | __be16 sport, __be16 dport) |
| 1528 | { |
| 1529 | __u32 seq; |
| 1530 | __u32 hash[12]; |
| 1531 | struct keydata *keyptr = get_keyptr(); |
| 1532 | |
| 1533 | /* The procedure is the same as for IPv4, but addresses are longer. |
| 1534 | * Thus we must use twothirdsMD4Transform. |
| 1535 | */ |
| 1536 | |
| 1537 | memcpy(hash, saddr, 16); |
| 1538 | hash[4] = ((__force u16)sport << 16) + (__force u16)dport; |
| 1539 | memcpy(&hash[5], keyptr->secret, sizeof(__u32) * 7); |
| 1540 | |
| 1541 | seq = twothirdsMD4Transform((const __u32 *)daddr, hash) & HASH_MASK; |
| 1542 | seq += keyptr->count; |
| 1543 | |
| 1544 | seq += ktime_to_ns(ktime_get_real()); |
| 1545 | |
| 1546 | return seq; |
| 1547 | } |
| 1548 | EXPORT_SYMBOL(secure_tcpv6_sequence_number); |
| 1549 | #endif |
| 1550 | |
| 1551 | /* The code below is shamelessly stolen from secure_tcp_sequence_number(). |
| 1552 | * All blames to Andrey V. Savochkin <saw@msu.ru>. |
| 1553 | */ |
| 1554 | __u32 secure_ip_id(__be32 daddr) |
| 1555 | { |
| 1556 | struct keydata *keyptr; |
| 1557 | __u32 hash[4]; |
| 1558 | |
| 1559 | keyptr = get_keyptr(); |
| 1560 | |
| 1561 | /* |
| 1562 | * Pick a unique starting offset for each IP destination. |
| 1563 | * The dest ip address is placed in the starting vector, |
| 1564 | * which is then hashed with random data. |
| 1565 | */ |
| 1566 | hash[0] = (__force __u32)daddr; |
| 1567 | hash[1] = keyptr->secret[9]; |
| 1568 | hash[2] = keyptr->secret[10]; |
| 1569 | hash[3] = keyptr->secret[11]; |
| 1570 | |
| 1571 | return half_md4_transform(hash, keyptr->secret); |
| 1572 | } |
| 1573 | |
| 1574 | #ifdef CONFIG_INET |
| 1575 | |
| 1576 | __u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr, |
| 1577 | __be16 sport, __be16 dport) |
| 1578 | { |
| 1579 | __u32 seq; |
| 1580 | __u32 hash[4]; |
| 1581 | struct keydata *keyptr = get_keyptr(); |
| 1582 | |
| 1583 | /* |
| 1584 | * Pick a unique starting offset for each TCP connection endpoints |
| 1585 | * (saddr, daddr, sport, dport). |
| 1586 | * Note that the words are placed into the starting vector, which is |
| 1587 | * then mixed with a partial MD4 over random data. |
| 1588 | */ |
| 1589 | hash[0] = (__force u32)saddr; |
| 1590 | hash[1] = (__force u32)daddr; |
| 1591 | hash[2] = ((__force u16)sport << 16) + (__force u16)dport; |
| 1592 | hash[3] = keyptr->secret[11]; |
| 1593 | |
| 1594 | seq = half_md4_transform(hash, keyptr->secret) & HASH_MASK; |
| 1595 | seq += keyptr->count; |
| 1596 | /* |
| 1597 | * As close as possible to RFC 793, which |
| 1598 | * suggests using a 250 kHz clock. |
| 1599 | * Further reading shows this assumes 2 Mb/s networks. |
| 1600 | * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate. |
| 1601 | * For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but |
| 1602 | * we also need to limit the resolution so that the u32 seq |
| 1603 | * overlaps less than one time per MSL (2 minutes). |
| 1604 | * Choosing a clock of 64 ns period is OK. (period of 274 s) |
| 1605 | */ |
| 1606 | seq += ktime_to_ns(ktime_get_real()) >> 6; |
| 1607 | |
| 1608 | return seq; |
| 1609 | } |
| 1610 | |
| 1611 | /* Generate secure starting point for ephemeral IPV4 transport port search */ |
| 1612 | u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport) |
| 1613 | { |
| 1614 | struct keydata *keyptr = get_keyptr(); |
| 1615 | u32 hash[4]; |
| 1616 | |
| 1617 | /* |
| 1618 | * Pick a unique starting offset for each ephemeral port search |
| 1619 | * (saddr, daddr, dport) and 48bits of random data. |
| 1620 | */ |
| 1621 | hash[0] = (__force u32)saddr; |
| 1622 | hash[1] = (__force u32)daddr; |
| 1623 | hash[2] = (__force u32)dport ^ keyptr->secret[10]; |
| 1624 | hash[3] = keyptr->secret[11]; |
| 1625 | |
| 1626 | return half_md4_transform(hash, keyptr->secret); |
| 1627 | } |
| 1628 | EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral); |
| 1629 | |
| 1630 | #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) |
| 1631 | u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr, |
| 1632 | __be16 dport) |
| 1633 | { |
| 1634 | struct keydata *keyptr = get_keyptr(); |
| 1635 | u32 hash[12]; |
| 1636 | |
| 1637 | memcpy(hash, saddr, 16); |
| 1638 | hash[4] = (__force u32)dport; |
| 1639 | memcpy(&hash[5], keyptr->secret, sizeof(__u32) * 7); |
| 1640 | |
| 1641 | return twothirdsMD4Transform((const __u32 *)daddr, hash); |
| 1642 | } |
| 1643 | #endif |
| 1644 | |
| 1645 | #if defined(CONFIG_IP_DCCP) || defined(CONFIG_IP_DCCP_MODULE) |
| 1646 | /* Similar to secure_tcp_sequence_number but generate a 48 bit value |
| 1647 | * bit's 32-47 increase every key exchange |
| 1648 | * 0-31 hash(source, dest) |
| 1649 | */ |
| 1650 | u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr, |
| 1651 | __be16 sport, __be16 dport) |
| 1652 | { |
| 1653 | u64 seq; |
| 1654 | __u32 hash[4]; |
| 1655 | struct keydata *keyptr = get_keyptr(); |
| 1656 | |
| 1657 | hash[0] = (__force u32)saddr; |
| 1658 | hash[1] = (__force u32)daddr; |
| 1659 | hash[2] = ((__force u16)sport << 16) + (__force u16)dport; |
| 1660 | hash[3] = keyptr->secret[11]; |
| 1661 | |
| 1662 | seq = half_md4_transform(hash, keyptr->secret); |
| 1663 | seq |= ((u64)keyptr->count) << (32 - HASH_BITS); |
| 1664 | |
| 1665 | seq += ktime_to_ns(ktime_get_real()); |
| 1666 | seq &= (1ull << 48) - 1; |
| 1667 | |
| 1668 | return seq; |
| 1669 | } |
| 1670 | EXPORT_SYMBOL(secure_dccp_sequence_number); |
| 1671 | #endif |
| 1672 | |
| 1673 | #endif /* CONFIG_INET */ |
| 1674 | |
| 1675 | |
| 1676 | /* |
| 1677 | * Get a random word for internal kernel use only. Similar to urandom but |
| 1678 | * with the goal of minimal entropy pool depletion. As a result, the random |
| 1679 | * value is not cryptographically secure but for several uses the cost of |
| 1680 | * depleting entropy is too high |
| 1681 | */ |
| 1682 | DEFINE_PER_CPU(__u32 [4], get_random_int_hash); |
| 1683 | unsigned int get_random_int(void) |
| 1684 | { |
| 1685 | struct keydata *keyptr; |
| 1686 | __u32 *hash = get_cpu_var(get_random_int_hash); |
| 1687 | int ret; |
| 1688 | |
| 1689 | keyptr = get_keyptr(); |
| 1690 | hash[0] += current->pid + jiffies + get_cycles(); |
| 1691 | |
| 1692 | ret = half_md4_transform(hash, keyptr->secret); |
| 1693 | put_cpu_var(get_random_int_hash); |
| 1694 | |
| 1695 | return ret; |
| 1696 | } |
| 1697 | |
| 1698 | /* |
| 1699 | * randomize_range() returns a start address such that |
| 1700 | * |
| 1701 | * [...... <range> .....] |
| 1702 | * start end |
| 1703 | * |
| 1704 | * a <range> with size "len" starting at the return value is inside in the |
| 1705 | * area defined by [start, end], but is otherwise randomized. |
| 1706 | */ |
| 1707 | unsigned long |
| 1708 | randomize_range(unsigned long start, unsigned long end, unsigned long len) |
| 1709 | { |
| 1710 | unsigned long range = end - len - start; |
| 1711 | |
| 1712 | if (end <= start + len) |
| 1713 | return 0; |
| 1714 | return PAGE_ALIGN(get_random_int() % range + start); |
| 1715 | } |