/*- * Copyright (c) 2017 Oliver Pinter * Copyright (c) 2017 W. Dean Freeman * Copyright (c) 2000-2015 Mark R V Murray * Copyright (c) 2013 Arthur Mesh * Copyright (c) 2004 Robert N. M. Watson * 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, this list of conditions and the following disclaimer * in this position and unchanged. * 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. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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. * */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if defined(RANDOM_ENABLE_ETHER) #define _RANDOM_HARVEST_ETHER_OFF 0 #else #define _RANDOM_HARVEST_ETHER_OFF (1u << RANDOM_NET_ETHER) #endif #if defined(RANDOM_ENABLE_UMA) #define _RANDOM_HARVEST_UMA_OFF 0 #else #define _RANDOM_HARVEST_UMA_OFF (1u << RANDOM_UMA) #endif /* * Note that random_sources_feed() will also use this to try and split up * entropy into a subset of pools per iteration with the goal of feeding * HARVESTSIZE into every pool at least once per second. */ #define RANDOM_KTHREAD_HZ 10 static void random_kthread(void); static void random_sources_feed(void); /* * Random must initialize much earlier than epoch, but we can initialize the * epoch code before SMP starts. Prior to SMP, we can safely bypass * concurrency primitives. */ static __read_mostly bool epoch_inited; static __read_mostly epoch_t rs_epoch; /* * How many events to queue up. We create this many items in * an 'empty' queue, then transfer them to the 'harvest' queue with * supplied junk. When used, they are transferred back to the * 'empty' queue. */ #define RANDOM_RING_MAX 1024 #define RANDOM_ACCUM_MAX 8 /* 1 to let the kernel thread run, 0 to terminate, -1 to mark completion */ volatile int random_kthread_control; /* Allow the sysadmin to select the broad category of * entropy types to harvest. */ __read_frequently u_int hc_source_mask; struct random_sources { CK_LIST_ENTRY(random_sources) rrs_entries; struct random_source *rrs_source; }; static CK_LIST_HEAD(sources_head, random_sources) source_list = CK_LIST_HEAD_INITIALIZER(source_list); SYSCTL_NODE(_kern_random, OID_AUTO, harvest, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, "Entropy Device Parameters"); /* * Put all the harvest queue context stuff in one place. * this make is a bit easier to lock and protect. */ static struct harvest_context { /* The harvest mutex protects all of harvest_context and * the related data. */ struct mtx hc_mtx; /* Round-robin destination cache. */ u_int hc_destination[ENTROPYSOURCE]; /* The context of the kernel thread processing harvested entropy */ struct proc *hc_kthread_proc; /* * Lockless ring buffer holding entropy events * If ring.in == ring.out, * the buffer is empty. * If ring.in != ring.out, * the buffer contains harvested entropy. * If (ring.in + 1) == ring.out (mod RANDOM_RING_MAX), * the buffer is full. * * NOTE: ring.in points to the last added element, * and ring.out points to the last consumed element. * * The ring.in variable needs locking as there are multiple * sources to the ring. Only the sources may change ring.in, * but the consumer may examine it. * * The ring.out variable does not need locking as there is * only one consumer. Only the consumer may change ring.out, * but the sources may examine it. */ struct entropy_ring { struct harvest_event ring[RANDOM_RING_MAX]; volatile u_int in; volatile u_int out; } hc_entropy_ring; struct fast_entropy_accumulator { volatile u_int pos; uint32_t buf[RANDOM_ACCUM_MAX]; } hc_entropy_fast_accumulator; } harvest_context; static struct kproc_desc random_proc_kp = { "rand_harvestq", random_kthread, &harvest_context.hc_kthread_proc, }; /* Pass the given event straight through to Fortuna/Whatever. */ static __inline void random_harvestq_fast_process_event(struct harvest_event *event) { p_random_alg_context->ra_event_processor(event); explicit_bzero(event, sizeof(*event)); } static void random_kthread(void) { u_int maxloop, ring_out, i; /* * Locking is not needed as this is the only place we modify ring.out, and * we only examine ring.in without changing it. Both of these are volatile, * and this is a unique thread. */ for (random_kthread_control = 1; random_kthread_control;) { /* Deal with events, if any. Restrict the number we do in one go. */ maxloop = RANDOM_RING_MAX; while (harvest_context.hc_entropy_ring.out != harvest_context.hc_entropy_ring.in) { ring_out = (harvest_context.hc_entropy_ring.out + 1)%RANDOM_RING_MAX; random_harvestq_fast_process_event(harvest_context.hc_entropy_ring.ring + ring_out); harvest_context.hc_entropy_ring.out = ring_out; if (!--maxloop) break; } random_sources_feed(); /* XXX: FIX!! Increase the high-performance data rate? Need some measurements first. */ for (i = 0; i < RANDOM_ACCUM_MAX; i++) { if (harvest_context.hc_entropy_fast_accumulator.buf[i]) { random_harvest_direct(harvest_context.hc_entropy_fast_accumulator.buf + i, sizeof(harvest_context.hc_entropy_fast_accumulator.buf[0]), RANDOM_UMA); harvest_context.hc_entropy_fast_accumulator.buf[i] = 0; } } /* XXX: FIX!! This is a *great* place to pass hardware/live entropy to random(9) */ tsleep_sbt(&harvest_context.hc_kthread_proc, 0, "-", SBT_1S/RANDOM_KTHREAD_HZ, 0, C_PREL(1)); } random_kthread_control = -1; wakeup(&harvest_context.hc_kthread_proc); kproc_exit(0); /* NOTREACHED */ } /* This happens well after SI_SUB_RANDOM */ SYSINIT(random_device_h_proc, SI_SUB_KICK_SCHEDULER, SI_ORDER_ANY, kproc_start, &random_proc_kp); static void rs_epoch_init(void *dummy __unused) { rs_epoch = epoch_alloc("Random Sources", EPOCH_PREEMPT); epoch_inited = true; } SYSINIT(rs_epoch_init, SI_SUB_EPOCH, SI_ORDER_ANY, rs_epoch_init, NULL); /* * Run through all fast sources reading entropy for the given * number of rounds, which should be a multiple of the number * of entropy accumulation pools in use; it is 32 for Fortuna. */ static void random_sources_feed(void) { uint32_t entropy[HARVESTSIZE]; struct epoch_tracker et; struct random_sources *rrs; u_int i, n, npools; bool rse_warm; rse_warm = epoch_inited; /* * Evenly-ish distribute pool population across the second based on how * frequently random_kthread iterates. * * For Fortuna, the math currently works out as such: * * 64 bits * 4 pools = 256 bits per iteration * 256 bits * 10 Hz = 2560 bits per second, 320 B/s * */ npools = howmany(p_random_alg_context->ra_poolcount, RANDOM_KTHREAD_HZ); /* * Step over all of live entropy sources, and feed their output * to the system-wide RNG. */ if (rse_warm) epoch_enter_preempt(rs_epoch, &et); CK_LIST_FOREACH(rrs, &source_list, rrs_entries) { for (i = 0; i < npools; i++) { n = rrs->rrs_source->rs_read(entropy, sizeof(entropy)); KASSERT((n <= sizeof(entropy)), ("%s: rs_read returned too much data (%u > %zu)", __func__, n, sizeof(entropy))); /* * Sometimes the HW entropy source doesn't have anything * ready for us. This isn't necessarily untrustworthy. * We don't perform any other verification of an entropy * source (i.e., length is allowed to be anywhere from 1 * to sizeof(entropy), quality is unchecked, etc), so * don't balk verbosely at slow random sources either. * There are reports that RDSEED on x86 metal falls * behind the rate at which we query it, for example. * But it's still a better entropy source than RDRAND. */ if (n == 0) continue; random_harvest_direct(entropy, n, rrs->rrs_source->rs_source); } } if (rse_warm) epoch_exit_preempt(rs_epoch, &et); explicit_bzero(entropy, sizeof(entropy)); } /* ARGSUSED */ static int random_check_uint_harvestmask(SYSCTL_HANDLER_ARGS) { static const u_int user_immutable_mask = (((1 << ENTROPYSOURCE) - 1) & (-1UL << RANDOM_PURE_START)) | _RANDOM_HARVEST_ETHER_OFF | _RANDOM_HARVEST_UMA_OFF; int error; u_int value, orig_value; orig_value = value = hc_source_mask; error = sysctl_handle_int(oidp, &value, 0, req); if (error != 0 || req->newptr == NULL) return (error); if (flsl(value) > ENTROPYSOURCE) return (EINVAL); /* * Disallow userspace modification of pure entropy sources. */ hc_source_mask = (value & ~user_immutable_mask) | (orig_value & user_immutable_mask); return (0); } SYSCTL_PROC(_kern_random_harvest, OID_AUTO, mask, CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0, random_check_uint_harvestmask, "IU", "Entropy harvesting mask"); /* ARGSUSED */ static int random_print_harvestmask(SYSCTL_HANDLER_ARGS) { struct sbuf sbuf; int error, i; error = sysctl_wire_old_buffer(req, 0); if (error == 0) { sbuf_new_for_sysctl(&sbuf, NULL, 128, req); for (i = ENTROPYSOURCE - 1; i >= 0; i--) sbuf_cat(&sbuf, (hc_source_mask & (1 << i)) ? "1" : "0"); error = sbuf_finish(&sbuf); sbuf_delete(&sbuf); } return (error); } SYSCTL_PROC(_kern_random_harvest, OID_AUTO, mask_bin, CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, random_print_harvestmask, "A", "Entropy harvesting mask (printable)"); static const char *random_source_descr[ENTROPYSOURCE] = { [RANDOM_CACHED] = "CACHED", [RANDOM_ATTACH] = "ATTACH", [RANDOM_KEYBOARD] = "KEYBOARD", [RANDOM_MOUSE] = "MOUSE", [RANDOM_NET_TUN] = "NET_TUN", [RANDOM_NET_ETHER] = "NET_ETHER", [RANDOM_NET_NG] = "NET_NG", [RANDOM_INTERRUPT] = "INTERRUPT", [RANDOM_SWI] = "SWI", [RANDOM_FS_ATIME] = "FS_ATIME", [RANDOM_UMA] = "UMA", /* ENVIRONMENTAL_END */ [RANDOM_PURE_OCTEON] = "PURE_OCTEON", /* PURE_START */ [RANDOM_PURE_SAFE] = "PURE_SAFE", [RANDOM_PURE_GLXSB] = "PURE_GLXSB", [RANDOM_PURE_HIFN] = "PURE_HIFN", [RANDOM_PURE_RDRAND] = "PURE_RDRAND", [RANDOM_PURE_NEHEMIAH] = "PURE_NEHEMIAH", [RANDOM_PURE_RNDTEST] = "PURE_RNDTEST", [RANDOM_PURE_VIRTIO] = "PURE_VIRTIO", [RANDOM_PURE_BROADCOM] = "PURE_BROADCOM", [RANDOM_PURE_CCP] = "PURE_CCP", [RANDOM_PURE_DARN] = "PURE_DARN", [RANDOM_PURE_TPM] = "PURE_TPM", [RANDOM_PURE_VMGENID] = "VMGENID", /* "ENTROPYSOURCE" */ }; /* ARGSUSED */ static int random_print_harvestmask_symbolic(SYSCTL_HANDLER_ARGS) { struct sbuf sbuf; int error, i; bool first; first = true; error = sysctl_wire_old_buffer(req, 0); if (error == 0) { sbuf_new_for_sysctl(&sbuf, NULL, 128, req); for (i = ENTROPYSOURCE - 1; i >= 0; i--) { if (i >= RANDOM_PURE_START && (hc_source_mask & (1 << i)) == 0) continue; if (!first) sbuf_cat(&sbuf, ","); sbuf_cat(&sbuf, !(hc_source_mask & (1 << i)) ? "[" : ""); sbuf_cat(&sbuf, random_source_descr[i]); sbuf_cat(&sbuf, !(hc_source_mask & (1 << i)) ? "]" : ""); first = false; } error = sbuf_finish(&sbuf); sbuf_delete(&sbuf); } return (error); } SYSCTL_PROC(_kern_random_harvest, OID_AUTO, mask_symbolic, CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, random_print_harvestmask_symbolic, "A", "Entropy harvesting mask (symbolic)"); /* ARGSUSED */ static void random_harvestq_init(void *unused __unused) { static const u_int almost_everything_mask = (((1 << (RANDOM_ENVIRONMENTAL_END + 1)) - 1) & ~_RANDOM_HARVEST_ETHER_OFF & ~_RANDOM_HARVEST_UMA_OFF); hc_source_mask = almost_everything_mask; RANDOM_HARVEST_INIT_LOCK(); harvest_context.hc_entropy_ring.in = harvest_context.hc_entropy_ring.out = 0; } SYSINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_THIRD, random_harvestq_init, NULL); /* * Subroutine to slice up a contiguous chunk of 'entropy' and feed it into the * underlying algorithm. Returns number of bytes actually fed into underlying * algorithm. */ static size_t random_early_prime(char *entropy, size_t len) { struct harvest_event event; size_t i; len = rounddown(len, sizeof(event.he_entropy)); if (len == 0) return (0); for (i = 0; i < len; i += sizeof(event.he_entropy)) { event.he_somecounter = (uint32_t)get_cyclecount(); event.he_size = sizeof(event.he_entropy); event.he_source = RANDOM_CACHED; event.he_destination = harvest_context.hc_destination[RANDOM_CACHED]++; memcpy(event.he_entropy, entropy + i, sizeof(event.he_entropy)); random_harvestq_fast_process_event(&event); } explicit_bzero(entropy, len); return (len); } /* * Subroutine to search for known loader-loaded files in memory and feed them * into the underlying algorithm early in boot. Returns the number of bytes * loaded (zero if none were loaded). */ static size_t random_prime_loader_file(const char *type) { uint8_t *keyfile, *data; size_t size; keyfile = preload_search_by_type(type); if (keyfile == NULL) return (0); data = preload_fetch_addr(keyfile); size = preload_fetch_size(keyfile); if (data == NULL) return (0); return (random_early_prime(data, size)); } /* * This is used to prime the RNG by grabbing any early random stuff * known to the kernel, and inserting it directly into the hashing * module, currently Fortuna. */ /* ARGSUSED */ static void random_harvestq_prime(void *unused __unused) { size_t size; /* * Get entropy that may have been preloaded by loader(8) * and use it to pre-charge the entropy harvest queue. */ size = random_prime_loader_file(RANDOM_CACHED_BOOT_ENTROPY_MODULE); if (bootverbose) { if (size > 0) printf("random: read %zu bytes from preloaded cache\n", size); else printf("random: no preloaded entropy cache\n"); } } SYSINIT(random_device_prime, SI_SUB_RANDOM, SI_ORDER_MIDDLE, random_harvestq_prime, NULL); /* ARGSUSED */ static void random_harvestq_deinit(void *unused __unused) { /* Command the hash/reseed thread to end and wait for it to finish */ random_kthread_control = 0; while (random_kthread_control >= 0) tsleep(&harvest_context.hc_kthread_proc, 0, "harvqterm", hz/5); } SYSUNINIT(random_device_h_init, SI_SUB_RANDOM, SI_ORDER_THIRD, random_harvestq_deinit, NULL); /*- * Entropy harvesting queue routine. * * This is supposed to be fast; do not do anything slow in here! * It is also illegal (and morally reprehensible) to insert any * high-rate data here. "High-rate" is defined as a data source * that will usually cause lots of failures of the "Lockless read" * check a few lines below. This includes the "always-on" sources * like the Intel "rdrand" or the VIA Nehamiah "xstore" sources. */ /* XXXRW: get_cyclecount() is cheap on most modern hardware, where cycle * counters are built in, but on older hardware it will do a real time clock * read which can be quite expensive. */ void random_harvest_queue_(const void *entropy, u_int size, enum random_entropy_source origin) { struct harvest_event *event; u_int ring_in; KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin)); RANDOM_HARVEST_LOCK(); ring_in = (harvest_context.hc_entropy_ring.in + 1)%RANDOM_RING_MAX; if (ring_in != harvest_context.hc_entropy_ring.out) { /* The ring is not full */ event = harvest_context.hc_entropy_ring.ring + ring_in; event->he_somecounter = (uint32_t)get_cyclecount(); event->he_source = origin; event->he_destination = harvest_context.hc_destination[origin]++; if (size <= sizeof(event->he_entropy)) { event->he_size = size; memcpy(event->he_entropy, entropy, size); } else { /* Big event, so squash it */ event->he_size = sizeof(event->he_entropy[0]); event->he_entropy[0] = jenkins_hash(entropy, size, (uint32_t)(uintptr_t)event); } harvest_context.hc_entropy_ring.in = ring_in; } RANDOM_HARVEST_UNLOCK(); } /*- * Entropy harvesting fast routine. * * This is supposed to be very fast; do not do anything slow in here! * This is the right place for high-rate harvested data. */ void random_harvest_fast_(const void *entropy, u_int size) { u_int pos; pos = harvest_context.hc_entropy_fast_accumulator.pos; harvest_context.hc_entropy_fast_accumulator.buf[pos] ^= jenkins_hash(entropy, size, (uint32_t)get_cyclecount()); harvest_context.hc_entropy_fast_accumulator.pos = (pos + 1)%RANDOM_ACCUM_MAX; } /*- * Entropy harvesting direct routine. * * This is not supposed to be fast, but will only be used during * (e.g.) booting when initial entropy is being gathered. */ void random_harvest_direct_(const void *entropy, u_int size, enum random_entropy_source origin) { struct harvest_event event; KASSERT(origin >= RANDOM_START && origin < ENTROPYSOURCE, ("%s: origin %d invalid\n", __func__, origin)); size = MIN(size, sizeof(event.he_entropy)); event.he_somecounter = (uint32_t)get_cyclecount(); event.he_size = size; event.he_source = origin; event.he_destination = harvest_context.hc_destination[origin]++; memcpy(event.he_entropy, entropy, size); random_harvestq_fast_process_event(&event); } void random_harvest_register_source(enum random_entropy_source source) { hc_source_mask |= (1 << source); } void random_harvest_deregister_source(enum random_entropy_source source) { hc_source_mask &= ~(1 << source); } void random_source_register(struct random_source *rsource) { struct random_sources *rrs; KASSERT(rsource != NULL, ("invalid input to %s", __func__)); rrs = malloc(sizeof(*rrs), M_ENTROPY, M_WAITOK); rrs->rrs_source = rsource; random_harvest_register_source(rsource->rs_source); printf("random: registering fast source %s\n", rsource->rs_ident); RANDOM_HARVEST_LOCK(); CK_LIST_INSERT_HEAD(&source_list, rrs, rrs_entries); RANDOM_HARVEST_UNLOCK(); } void random_source_deregister(struct random_source *rsource) { struct random_sources *rrs = NULL; KASSERT(rsource != NULL, ("invalid input to %s", __func__)); random_harvest_deregister_source(rsource->rs_source); RANDOM_HARVEST_LOCK(); CK_LIST_FOREACH(rrs, &source_list, rrs_entries) if (rrs->rrs_source == rsource) { CK_LIST_REMOVE(rrs, rrs_entries); break; } RANDOM_HARVEST_UNLOCK(); if (rrs != NULL && epoch_inited) epoch_wait_preempt(rs_epoch); free(rrs, M_ENTROPY); } static int random_source_handler(SYSCTL_HANDLER_ARGS) { struct epoch_tracker et; struct random_sources *rrs; struct sbuf sbuf; int error, count; error = sysctl_wire_old_buffer(req, 0); if (error != 0) return (error); sbuf_new_for_sysctl(&sbuf, NULL, 64, req); count = 0; epoch_enter_preempt(rs_epoch, &et); CK_LIST_FOREACH(rrs, &source_list, rrs_entries) { sbuf_cat(&sbuf, (count++ ? ",'" : "'")); sbuf_cat(&sbuf, rrs->rrs_source->rs_ident); sbuf_cat(&sbuf, "'"); } epoch_exit_preempt(rs_epoch, &et); error = sbuf_finish(&sbuf); sbuf_delete(&sbuf); return (error); } SYSCTL_PROC(_kern_random, OID_AUTO, random_sources, CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, random_source_handler, "A", "List of active fast entropy sources."); MODULE_VERSION(random_harvestq, 1);