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random(4): Gather entropy from Pure sources

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At initialization, hc_source_mask only includes non-Pure sources.

The patch changes source registration to enable the registered source in the
hc_source_mask bitmask. This mask governs which sources are harvested.

This patch also disallows userspace from disabling such sources.

PR:		222807
Submitted by:	W. Dean Freeman <badfilemagic AT gmail.com>
Reviewed by:	jmg (earlier version), delphij
Approved by:	secteam (delphij)
Obtained from:	HBSD 0054e3e170e083811acc9f3b637f8be8a86c03e7
Security:	yes
Differential Revision:	https://reviews.freebsd.org/D12611
This commit is contained in:
Conrad Meyer 2017-10-07 19:02:03 +00:00
parent f04c11c32b
commit 095db7e6e7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=324394
3 changed files with 62 additions and 8 deletions
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56
sys/dev/random/random_harvestq.c
View File

@ -1,4 +1,6 @@
/*-
* 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
@ -240,7 +242,27 @@ read_rate_increment(u_int chunk)
}
/* ARGSUSED */
RANDOM_CHECK_UINT(harvestmask, 0, RANDOM_HARVEST_EVERYTHING_MASK);
static int
random_check_uint_harvestmask(SYSCTL_HANDLER_ARGS)
{
int error;
u_int value, orig_value;
orig_value = value = harvest_context.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.
*/
harvest_context.hc_source_mask = (value & ~RANDOM_HARVEST_PURE_MASK) |
(orig_value & RANDOM_HARVEST_PURE_MASK);
return (0);
}
/* ARGSUSED */
static int
@ -252,7 +274,7 @@ random_print_harvestmask(SYSCTL_HANDLER_ARGS)
error = sysctl_wire_old_buffer(req, 0);
if (error == 0) {
sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
for (i = RANDOM_ENVIRONMENTAL_END; i >= 0; i--)
for (i = ENTROPYSOURCE - 1; i >= 0; i--)
sbuf_cat(&sbuf, (harvest_context.hc_source_mask & (1 << i)) ? "1" : "0");
error = sbuf_finish(&sbuf);
sbuf_delete(&sbuf);
@ -272,7 +294,7 @@ static const char *random_source_descr[ENTROPYSOURCE] = {
[RANDOM_SWI] = "SWI",
[RANDOM_FS_ATIME] = "FS_ATIME",
[RANDOM_UMA] = "UMA", /* ENVIRONMENTAL_END */
[RANDOM_PURE_OCTEON] = "PURE_OCTEON",
[RANDOM_PURE_OCTEON] = "PURE_OCTEON", /* PURE_START */
[RANDOM_PURE_SAFE] = "PURE_SAFE",
[RANDOM_PURE_GLXSB] = "PURE_GLXSB",
[RANDOM_PURE_UBSEC] = "PURE_UBSEC",
@ -291,15 +313,22 @@ 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 = RANDOM_ENVIRONMENTAL_END; i >= 0; i--) {
sbuf_cat(&sbuf, (i == RANDOM_ENVIRONMENTAL_END) ? "" : ",");
for (i = ENTROPYSOURCE - 1; i >= 0; i--) {
if (i >= RANDOM_PURE_START &&
(harvest_context.hc_source_mask & (1 << i)) == 0)
continue;
if (!first)
sbuf_cat(&sbuf, ",");
sbuf_cat(&sbuf, !(harvest_context.hc_source_mask & (1 << i)) ? "[" : "");
sbuf_cat(&sbuf, random_source_descr[i]);
sbuf_cat(&sbuf, !(harvest_context.hc_source_mask & (1 << i)) ? "]" : "");
first = false;
}
error = sbuf_finish(&sbuf);
sbuf_delete(&sbuf);
@ -321,8 +350,7 @@ random_harvestq_init(void *unused __unused)
SYSCTL_ADD_PROC(&random_clist,
SYSCTL_CHILDREN(random_sys_o),
OID_AUTO, "mask", CTLTYPE_UINT | CTLFLAG_RW,
&harvest_context.hc_source_mask, 0,
random_check_uint_harvestmask, "IU",
NULL, 0, random_check_uint_harvestmask, "IU",
"Entropy harvesting mask");
SYSCTL_ADD_PROC(&random_clist,
SYSCTL_CHILDREN(random_sys_o),
@ -495,4 +523,18 @@ random_harvest_direct(const void *entropy, u_int size, u_int bits, enum random_e
explicit_bzero(&event, sizeof(event));
}
void
random_harvest_register_source(enum random_entropy_source source)
{
harvest_context.hc_source_mask |= (1 << source);
}
void
random_harvest_deregister_source(enum random_entropy_source source)
{
harvest_context.hc_source_mask &= ~(1 << source);
}
MODULE_VERSION(random_harvestq, 1);

6
sys/dev/random/randomdev.c
View File

@ -1,4 +1,5 @@
/*-
* Copyright (c) 2017 Oliver Pinter
* Copyright (c) 2000-2015 Mark R V Murray
* All rights reserved.
*
@ -321,6 +322,8 @@ random_source_register(struct random_source *rsource)
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);
LIST_INSERT_HEAD(&source_list, rrs, rrs_entries);
}
@ -331,6 +334,9 @@ 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);
LIST_FOREACH(rrs, &source_list, rrs_entries)
if (rrs->rrs_source == rsource) {
LIST_REMOVE(rrs, rrs_entries);

8
sys/sys/random.h
View File

@ -81,7 +81,8 @@ enum random_entropy_source {
RANDOM_UMA, /* Special!! UMA/SLAB Allocator */
RANDOM_ENVIRONMENTAL_END = RANDOM_UMA,
/* Fast hardware random-number sources from here on. */
RANDOM_PURE_OCTEON,
RANDOM_PURE_START,
RANDOM_PURE_OCTEON = RANDOM_PURE_START,
RANDOM_PURE_SAFE,
RANDOM_PURE_GLXSB,
RANDOM_PURE_UBSEC,
@ -95,6 +96,7 @@ enum random_entropy_source {
};
#define RANDOM_HARVEST_EVERYTHING_MASK ((1 << (RANDOM_ENVIRONMENTAL_END + 1)) - 1)
#define RANDOM_HARVEST_PURE_MASK (((1 << ENTROPYSOURCE) - 1) & (-1UL << RANDOM_PURE_START))
#define RANDOM_LEGACY_BOOT_ENTROPY_MODULE "/boot/entropy"
#define RANDOM_CACHED_BOOT_ENTROPY_MODULE "boot_entropy_cache"
@ -104,10 +106,14 @@ enum random_entropy_source {
void random_harvest_queue(const void *, u_int, u_int, enum random_entropy_source);
void random_harvest_fast(const void *, u_int, u_int, enum random_entropy_source);
void random_harvest_direct(const void *, u_int, u_int, enum random_entropy_source);
void random_harvest_register_source(enum random_entropy_source);
void random_harvest_deregister_source(enum random_entropy_source);
#else
#define random_harvest_queue(a, b, c, d) do {} while (0)
#define random_harvest_fast(a, b, c, d) do {} while (0)
#define random_harvest_direct(a, b, c, d) do {} while (0)
#define random_harvest_register_source(a) do {} while (0)
#define random_harvest_deregister_source(a) do {} while (0)
#endif
#if defined(RANDOM_ENABLE_UMA)