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IABSD.fr/src/sys/dev/rnd.c
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/* $OpenBSD: rnd.c,v 1.204 2020/03/06 16:04:14 tobhe Exp $ */ /* * Copyright (c) 2011 Theo de Raadt. * Copyright (c) 2008 Damien Miller. * Copyright (c) 1996, 1997, 2000-2002 Michael Shalayeff. * Copyright (c) 2013 Markus Friedl. * 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 Public License, in which case the provisions of the GPL are * required INSTEAD OF the above restrictions. (This clause is * necessary due to a potential bad interaction between the GPL and * the restrictions contained in a BSD-style copyright.) * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED * OF THE POSSIBILITY OF SUCH DAMAGE. */ /* * 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 be easily generated by using an * 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. Instead, we must try to * gather "environmental noise" from the computer's environment, which * must be hard for outside attackers to observe and use 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 is * added to the "rnd states" queue; this is used as much of the * source material which is mixed on occasion using a CRC-like function * into the "entropy pool". This is not cryptographically strong, but * it is adequate assuming the randomness is not chosen maliciously, * and it is very fast because the interrupt-time event is only to add * a small random token to the "rnd states" queue. * * When random bytes are desired, they are obtained by pulling from * the entropy pool and running a SHA512 hash. The SHA512 hash avoids * exposing the internal state of the entropy pool. Even if it is * possible to analyze SHA512 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 SHA512 hash will continue to generate * output since there is no true risk because the SHA512 output is not * exported outside this subsystem. It is next used as input to seed a * ChaCha20 stream cipher, which is re-seeded from time to time. This * design provides very high amounts of output data from a potentially * small entropy base, at high enough speeds to encourage use of random * numbers in nearly any situation. Before OpenBSD 5.5, the RC4 stream * cipher (also known as ARC4) was used instead of ChaCha20. * * The output of this single ChaCha20 engine is then shared amongst many * consumers in the kernel and userland via a few interfaces: * arc4random_buf(), arc4random(), arc4random_uniform(), randomread() * for the set of /dev/random nodes and the system call getentropy(), * which provides seeds for process-context pseudorandom generators. * * 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 speeds 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 the 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. * * Using a RC4 stream cipher as 2nd stage after the MD5 (now SHA512) output * is the result of work by David Mazieres. */ #include <sys/param.h> #include <sys/systm.h> #include <sys/disk.h> #include <sys/event.h> #include <sys/limits.h> #include <sys/time.h> #include <sys/ioctl.h> #include <sys/malloc.h> #include <sys/fcntl.h> #include <sys/timeout.h> #include <sys/mutex.h> #include <sys/task.h> #include <sys/msgbuf.h> #include <sys/mount.h> #include <sys/syscallargs.h> #include <crypto/sha2.h> #define KEYSTREAM_ONLY #include <crypto/chacha_private.h> #include <dev/rndvar.h> #include <uvm/uvm_param.h> #include <uvm/uvm_extern.h> /* * For the purposes of better mixing, we use the CRC-32 polynomial as * well to make a twisted Generalized Feedback Shift Register * * (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 Modeling 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 * we want from it is to be a good non-cryptographic hash - * i.e. to 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 polynomial. 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 * polynomial, 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. */ /* * Stirring polynomials over GF(2) for various pool sizes. Used in * add_entropy_words() below. * * The polynomial terms are chosen to be evenly spaced (minimum RMS * distance from evenly spaced; except for the last tap, which is 1 to * get the twisting happening as fast as possible. * * The resultant polynomial is: * 2^POOLWORDS + 2^POOL_TAP1 + 2^POOL_TAP2 + 2^POOL_TAP3 + 2^POOL_TAP4 + 1 */ #define POOLWORDS 2048 #define POOLBYTES (POOLWORDS*4) #define POOLMASK (POOLWORDS - 1) #define POOL_TAP1 1638 #define POOL_TAP2 1231 #define POOL_TAP3 819 #define POOL_TAP4 411 /* * Raw entropy collection from device drivers; at interrupt context or not. * enqueue_randomness() provide data which is put into the entropy queue. */ #define QEVLEN 128 /* must be a power of 2 */ #define QEVSLOW (QEVLEN * 3 / 4) /* yet another 0.75 for 60-minutes hour /-; */ #define KEYSZ 32 #define IVSZ 8 #define BLOCKSZ 64 #define RSBUFSZ (16*BLOCKSZ) #define EBUFSIZE KEYSZ + IVSZ struct rand_event { u_int re_time; u_int re_val; } rnd_event_space[QEVLEN]; u_int rnd_event_cons; u_int rnd_event_prod; struct mutex rnd_enqlck = MUTEX_INITIALIZER(IPL_HIGH); struct mutex rnd_deqlck = MUTEX_INITIALIZER(IPL_HIGH); struct timeout rnd_timeout; static u_int32_t entropy_pool[POOLWORDS]; u_int32_t entropy_pool0[POOLWORDS] __attribute__((section(".openbsd.randomdata"))); u_int entropy_add_ptr; u_char entropy_input_rotate; void dequeue_randomness(void *); void add_entropy_words(const u_int32_t *, u_int); void extract_entropy(u_int8_t *) __attribute__((__bounded__(__minbytes__,1,EBUFSIZE))); int filt_randomread(struct knote *, long); void filt_randomdetach(struct knote *); int filt_randomwrite(struct knote *, long); static void _rs_seed(u_char *, size_t); static void _rs_clearseed(const void *p, size_t s); const struct filterops randomread_filtops = { .f_flags = FILTEROP_ISFD, .f_attach = NULL, .f_detach = filt_randomdetach, .f_event = filt_randomread, }; const struct filterops randomwrite_filtops = { .f_flags = FILTEROP_ISFD, .f_attach = NULL, .f_detach = filt_randomdetach, .f_event = filt_randomwrite, }; static inline struct rand_event * rnd_get(void) { u_int idx; /* nothing to do if queue is empty */ if (rnd_event_prod == rnd_event_cons) return NULL; if (rnd_event_prod - rnd_event_cons > QEVLEN) rnd_event_cons = rnd_event_prod - QEVLEN; idx = rnd_event_cons++; return &rnd_event_space[idx & (QEVLEN - 1)]; } static inline struct rand_event * rnd_put(void) { u_int idx = rnd_event_prod++; /* allow wrapping. caller will mix it in. */ return &rnd_event_space[idx & (QEVLEN - 1)]; } static inline u_int rnd_qlen(void) { return rnd_event_prod - rnd_event_cons; } /* * This function adds entropy to the entropy pool by using timing delays. * * The number "val" is also added to the pool - it should somehow describe * the type of event which just happened. Currently the values of 0-255 * are for keyboard scan codes, 256 and upwards - for interrupts. */ void enqueue_randomness(u_int val) { struct rand_event *rep; struct timespec ts; u_int qlen; timespecclear(&ts); if (timeout_initialized(&rnd_timeout)) nanotime(&ts); mtx_enter(&rnd_enqlck); rep = rnd_put(); rep->re_time += ts.tv_nsec ^ (ts.tv_sec << 20); rep->re_val += val; qlen = rnd_qlen(); mtx_leave(&rnd_enqlck); if (qlen > QEVSLOW/2 && timeout_initialized(&rnd_timeout) && !timeout_pending(&rnd_timeout)) timeout_add(&rnd_timeout, 1); } /* * This function adds a byte into the entropy pool. It does not * update the entropy estimate. The caller must do this if appropriate. * * The pool is stirred with a polynomial of degree POOLWORDS over GF(2); * see POOL_TAP[1-4] above * * Rotate the input word by a changing number of bits, to help assure * that all bits in the entropy get toggled. Otherwise, if the pool * is consistently fed small numbers (such as keyboard scan codes) * then the upper bits of the entropy pool will frequently remain * untouched. */ void add_entropy_words(const u_int32_t *buf, u_int n) { /* derived from IEEE 802.3 CRC-32 */ static const u_int32_t twist_table[8] = { 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158, 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; for (; n--; buf++) { u_int32_t w = (*buf << entropy_input_rotate) | (*buf >> ((32 - entropy_input_rotate) & 31)); u_int i = entropy_add_ptr = (entropy_add_ptr - 1) & POOLMASK; /* * 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. */ entropy_input_rotate = (entropy_input_rotate + (i ? 7 : 14)) & 31; /* XOR pool contents corresponding to polynomial terms */ w ^= entropy_pool[(i + POOL_TAP1) & POOLMASK] ^ entropy_pool[(i + POOL_TAP2) & POOLMASK] ^ entropy_pool[(i + POOL_TAP3) & POOLMASK] ^ entropy_pool[(i + POOL_TAP4) & POOLMASK] ^ entropy_pool[(i + 1) & POOLMASK] ^ entropy_pool[i]; /* + 2^POOLWORDS */ entropy_pool[i] = (w >> 3) ^ twist_table[w & 7]; } } /* * Pulls entropy out of the queue and merges it into the pool * with the CRC. */ /* ARGSUSED */ void dequeue_randomness(void *v) { struct rand_event *rep; u_int32_t buf[2]; if (timeout_initialized(&rnd_timeout)) timeout_del(&rnd_timeout); mtx_enter(&rnd_deqlck); while ((rep = rnd_get())) { buf[0] = rep->re_time; buf[1] = rep->re_val; mtx_leave(&rnd_deqlck); add_entropy_words(buf, 2); mtx_enter(&rnd_deqlck); } mtx_leave(&rnd_deqlck); } /* * Grabs a chunk from the entropy_pool[] and slams it through SHA512 when * requested. */ void extract_entropy(u_int8_t *buf) { static u_int32_t extract_pool[POOLWORDS]; u_char digest[SHA512_DIGEST_LENGTH]; SHA2_CTX shactx; #if SHA512_DIGEST_LENGTH < EBUFSIZE #error "need more bigger hash output" #endif /* * INTENTIONALLY not protected by any lock. Races during * memcpy() result in acceptable input data; races during * SHA512Update() would create nasty data dependencies. We * do not rely on this as a benefit, but if it happens, cool. */ memcpy(extract_pool, entropy_pool, sizeof(extract_pool)); /* Hash the pool to get the output */ SHA512Init(&shactx); SHA512Update(&shactx, (u_int8_t *)extract_pool, sizeof(extract_pool)); SHA512Final(digest, &shactx); /* Copy data to destination buffer */ memcpy(buf, digest, EBUFSIZE); /* Modify pool so next hash will produce different results */ enqueue_randomness(EBUFSIZE); dequeue_randomness(NULL); /* Wipe data from memory */ explicit_bzero(extract_pool, sizeof(extract_pool)); explicit_bzero(digest, sizeof(digest)); } /* random keystream by ChaCha */ void rnd_reinit(void *v); /* timeout to start reinit */ void rnd_init(void *); /* actually do the reinit */ struct mutex rndlock = MUTEX_INITIALIZER(IPL_HIGH); struct timeout rndreinit_timeout; struct task rnd_task = TASK_INITIALIZER(rnd_init, NULL); static chacha_ctx rs; /* chacha context for random keystream */ /* keystream blocks (also chacha seed from boot) */ static u_char rs_buf[RSBUFSZ]; u_char rs_buf0[RSBUFSZ] __attribute__((section(".openbsd.randomdata"))); static size_t rs_have; /* valid bytes at end of rs_buf */ static size_t rs_count; /* bytes till reseed */ void suspend_randomness(void) { struct timespec ts; getnanotime(&ts); enqueue_randomness(ts.tv_sec); enqueue_randomness(ts.tv_nsec); dequeue_randomness(NULL); rs_count = 0; arc4random_buf(entropy_pool, sizeof(entropy_pool)); } void resume_randomness(char *buf, size_t buflen) { struct timespec ts; if (buf && buflen) _rs_seed(buf, buflen); getnanotime(&ts); enqueue_randomness(ts.tv_sec); enqueue_randomness(ts.tv_nsec); dequeue_randomness(NULL); rs_count = 0; } static inline void _rs_rekey(u_char *dat, size_t datlen); static inline void _rs_init(u_char *buf, size_t n) { KASSERT(n >= KEYSZ + IVSZ); chacha_keysetup(&rs, buf, KEYSZ * 8); chacha_ivsetup(&rs, buf + KEYSZ, NULL); } static void _rs_seed(u_char *buf, size_t n) { _rs_rekey(buf, n); /* invalidate rs_buf */ rs_have = 0; memset(rs_buf, 0, RSBUFSZ); rs_count = 1600000; } static void _rs_stir(int do_lock) { struct timespec ts; u_int8_t buf[EBUFSIZE], *p; int i; /* * Use SHA512 PRNG data and a system timespec; early in the boot * process this is the best we can do -- some architectures do * not collect entropy very well during this time, but may have * clock information which is better than nothing. */ extract_entropy(buf); nanotime(&ts); for (p = (u_int8_t *)&ts, i = 0; i < sizeof(ts); i++) buf[i] ^= p[i]; if (do_lock) mtx_enter(&rndlock); _rs_seed(buf, sizeof(buf)); if (do_lock) mtx_leave(&rndlock); explicit_bzero(buf, sizeof(buf)); } static inline void _rs_stir_if_needed(size_t len) { static int rs_initialized; if (!rs_initialized) { memcpy(entropy_pool, entropy_pool0, sizeof entropy_pool); memcpy(rs_buf, rs_buf0, sizeof rs_buf); /* seeds cannot be cleaned yet, random_start() will do so */ _rs_init(rs_buf, KEYSZ + IVSZ); rs_count = 1024 * 1024 * 1024; /* until main() runs */ rs_initialized = 1; } else if (rs_count <= len) _rs_stir(0); else rs_count -= len; } static void _rs_clearseed(const void *p, size_t s) { struct kmem_dyn_mode kd_avoidalias; vaddr_t va = trunc_page((vaddr_t)p); vsize_t off = (vaddr_t)p - va; vsize_t len; vaddr_t rwva; paddr_t pa; while (s > 0) { pmap_extract(pmap_kernel(), va, &pa); memset(&kd_avoidalias, 0, sizeof kd_avoidalias); kd_avoidalias.kd_prefer = pa; kd_avoidalias.kd_waitok = 1; rwva = (vaddr_t)km_alloc(PAGE_SIZE, &kv_any, &kp_none, &kd_avoidalias); if (!rwva) panic("_rs_clearseed"); pmap_kenter_pa(rwva, pa, PROT_READ | PROT_WRITE); pmap_update(pmap_kernel()); len = MIN(s, PAGE_SIZE - off); explicit_bzero((void *)(rwva + off), len); pmap_kremove(rwva, PAGE_SIZE); km_free((void *)rwva, PAGE_SIZE, &kv_any, &kp_none); va += PAGE_SIZE; s -= len; off = 0; } } static inline void _rs_rekey(u_char *dat, size_t datlen) { #ifndef KEYSTREAM_ONLY memset(rs_buf, 0, RSBUFSZ); #endif /* fill rs_buf with the keystream */ chacha_encrypt_bytes(&rs, rs_buf, rs_buf, RSBUFSZ); /* mix in optional user provided data */ if (dat) { size_t i, m; m = MIN(datlen, KEYSZ + IVSZ); for (i = 0; i < m; i++) rs_buf[i] ^= dat[i]; } /* immediately reinit for backtracking resistance */ _rs_init(rs_buf, KEYSZ + IVSZ); memset(rs_buf, 0, KEYSZ + IVSZ); rs_have = RSBUFSZ - KEYSZ - IVSZ; } static inline void _rs_random_buf(void *_buf, size_t n) { u_char *buf = (u_char *)_buf; size_t m; _rs_stir_if_needed(n); while (n > 0) { if (rs_have > 0) { m = MIN(n, rs_have); memcpy(buf, rs_buf + RSBUFSZ - rs_have, m); memset(rs_buf + RSBUFSZ - rs_have, 0, m); buf += m; n -= m; rs_have -= m; } if (rs_have == 0) _rs_rekey(NULL, 0); } } static inline void _rs_random_u32(u_int32_t *val) { _rs_stir_if_needed(sizeof(*val)); if (rs_have < sizeof(*val)) _rs_rekey(NULL, 0); memcpy(val, rs_buf + RSBUFSZ - rs_have, sizeof(*val)); memset(rs_buf + RSBUFSZ - rs_have, 0, sizeof(*val)); rs_have -= sizeof(*val); } /* Return one word of randomness from a ChaCha20 generator */ u_int32_t arc4random(void) { u_int32_t ret; mtx_enter(&rndlock); _rs_random_u32(&ret); mtx_leave(&rndlock); return ret; } /* * Fill a buffer of arbitrary length with ChaCha20-derived randomness. */ void arc4random_buf(void *buf, size_t n) { mtx_enter(&rndlock); _rs_random_buf(buf, n); mtx_leave(&rndlock); } /* * Allocate a new ChaCha20 context for the caller to use. */ struct arc4random_ctx * arc4random_ctx_new() { char keybuf[KEYSZ + IVSZ]; chacha_ctx *ctx = malloc(sizeof(chacha_ctx), M_TEMP, M_WAITOK); arc4random_buf(keybuf, KEYSZ + IVSZ); chacha_keysetup(ctx, keybuf, KEYSZ * 8); chacha_ivsetup(ctx, keybuf + KEYSZ, NULL); explicit_bzero(keybuf, sizeof(keybuf)); return (struct arc4random_ctx *)ctx; } /* * Free a ChaCha20 context created by arc4random_ctx_new() */ void arc4random_ctx_free(struct arc4random_ctx *ctx) { explicit_bzero(ctx, sizeof(chacha_ctx)); free(ctx, M_TEMP, sizeof(chacha_ctx)); } /* * Use a given ChaCha20 context to fill a buffer */ void arc4random_ctx_buf(struct arc4random_ctx *ctx, void *buf, size_t n) { chacha_encrypt_bytes((chacha_ctx *)ctx, buf, buf, n); } /* * Calculate a uniformly distributed random number less than upper_bound * avoiding "modulo bias". * * Uniformity is achieved by generating new random numbers until the one * returned is outside the range [0, 2**32 % upper_bound). This * guarantees the selected random number will be inside * [2**32 % upper_bound, 2**32) which maps back to [0, upper_bound) * after reduction modulo upper_bound. */ u_int32_t arc4random_uniform(u_int32_t upper_bound) { u_int32_t r, min; if (upper_bound < 2) return 0; /* 2**32 % x == (2**32 - x) % x */ min = -upper_bound % upper_bound; /* * This could theoretically loop forever but each retry has * p > 0.5 (worst case, usually far better) of selecting a * number inside the range we need, so it should rarely need * to re-roll. */ for (;;) { r = arc4random(); if (r >= min) break; } return r % upper_bound; } /* ARGSUSED */ void rnd_init(void *null) { _rs_stir(1); } /* * Called by timeout to mark arc4 for stirring, */ void rnd_reinit(void *v) { task_add(systq, &rnd_task); /* 10 minutes, per dm@'s suggestion */ timeout_add_sec(&rndreinit_timeout, 10 * 60); } /* * Start periodic services inside the random subsystem, which pull * entropy forward, hash it, and re-seed the random stream as needed. */ void random_start(void) { extern char etext[]; #if !defined(NO_PROPOLICE) extern long __guard_local; if (__guard_local == 0) printf("warning: no entropy supplied by boot loader\n"); #endif _rs_clearseed(entropy_pool0, sizeof entropy_pool0); _rs_clearseed(rs_buf0, sizeof rs_buf0); /* Message buffer may contain data from previous boot */ if (msgbufp->msg_magic == MSG_MAGIC) add_entropy_words((u_int32_t *)msgbufp->msg_bufc, msgbufp->msg_bufs / sizeof(u_int32_t)); add_entropy_words((u_int32_t *)etext - 32*1024, 8192/sizeof(u_int32_t)); dequeue_randomness(NULL); rnd_init(NULL); timeout_set(&rndreinit_timeout, rnd_reinit, NULL); rnd_reinit(NULL); timeout_set(&rnd_timeout, dequeue_randomness, NULL); } int randomopen(dev_t dev, int flag, int mode, struct proc *p) { return 0; } int randomclose(dev_t dev, int flag, int mode, struct proc *p) { return 0; } /* * Maximum number of bytes to serve directly from the main ChaCha * pool. Larger requests are served from a discrete ChaCha instance keyed * from the main pool. */ #define RND_MAIN_MAX_BYTES 2048 int randomread(dev_t dev, struct uio *uio, int ioflag) { u_char lbuf[KEYSZ+IVSZ]; chacha_ctx lctx; size_t total = uio->uio_resid; u_char *buf; int myctx = 0, ret = 0; if (uio->uio_resid == 0) return 0; buf = malloc(POOLBYTES, M_TEMP, M_WAITOK); if (total > RND_MAIN_MAX_BYTES) { arc4random_buf(lbuf, sizeof(lbuf)); chacha_keysetup(&lctx, lbuf, KEYSZ * 8); chacha_ivsetup(&lctx, lbuf + KEYSZ, NULL); explicit_bzero(lbuf, sizeof(lbuf)); myctx = 1; } while (ret == 0 && uio->uio_resid > 0) { size_t n = ulmin(POOLBYTES, uio->uio_resid); if (myctx) { #ifndef KEYSTREAM_ONLY memset(buf, 0, n); #endif chacha_encrypt_bytes(&lctx, buf, buf, n); } else arc4random_buf(buf, n); ret = uiomove(buf, n, uio); if (ret == 0 && uio->uio_resid > 0) yield(); } if (myctx) explicit_bzero(&lctx, sizeof(lctx)); explicit_bzero(buf, POOLBYTES); free(buf, M_TEMP, POOLBYTES); return ret; } int randomwrite(dev_t dev, struct uio *uio, int flags) { int ret = 0, newdata = 0; u_int32_t *buf; if (uio->uio_resid == 0) return 0; buf = malloc(POOLBYTES, M_TEMP, M_WAITOK); while (ret == 0 && uio->uio_resid > 0) { size_t n = ulmin(POOLBYTES, uio->uio_resid); ret = uiomove(buf, n, uio); if (ret != 0) break; while (n % sizeof(u_int32_t)) ((u_int8_t *)buf)[n++] = 0; add_entropy_words(buf, n / 4); if (uio->uio_resid > 0) yield(); newdata = 1; } if (newdata) rnd_init(NULL); explicit_bzero(buf, POOLBYTES); free(buf, M_TEMP, POOLBYTES); return ret; } int randomkqfilter(dev_t dev, struct knote *kn) { switch (kn->kn_filter) { case EVFILT_READ: kn->kn_fop = &randomread_filtops; break; case EVFILT_WRITE: kn->kn_fop = &randomwrite_filtops; break; default: return (EINVAL); } return (0); } void filt_randomdetach(struct knote *kn) { } int filt_randomread(struct knote *kn, long hint) { kn->kn_data = RND_MAIN_MAX_BYTES; return (1); } int filt_randomwrite(struct knote *kn, long hint) { kn->kn_data = POOLBYTES; return (1); } int randomioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct proc *p) { switch (cmd) { case FIOASYNC: /* No async flag in softc so this is a no-op. */ break; case FIONBIO: /* Handled in the upper FS layer. */ break; default: return ENOTTY; } return 0; } int sys_getentropy(struct proc *p, void *v, register_t *retval) { struct sys_getentropy_args /* { syscallarg(void *) buf; syscallarg(size_t) nbyte; } */ *uap = v; char buf[256]; int error; if (SCARG(uap, nbyte) > sizeof(buf)) return (EIO); arc4random_buf(buf, SCARG(uap, nbyte)); if ((error = copyout(buf, SCARG(uap, buf), SCARG(uap, nbyte))) != 0) return (error); explicit_bzero(buf, sizeof(buf)); retval[0] = 0; return (0); }