From af3b530773231f8cff6548e36962ad1f25e38c5d Mon Sep 17 00:00:00 2001
From: Evan Hunt <each@isc.org>
Date: Thu, 28 Sep 2017 10:09:22 -0700
Subject: [PATCH] completed and corrected the crypto-random change
4724. [func] By default, BIND now uses the random number
functions provided by the crypto library (i.e.,
OpenSSL or a PKCS#11 provider) as a source of
randomness rather than /dev/random. This is
suitable for virtual machine environments
which have limited entropy pools and lack
hardware random number generators.
This can be overridden by specifying another
entropy source via the "random-device" option
in named.conf, or via the -r command line option;
however, for functions requiring full cryptographic
strength, such as DNSSEC key generation, this
cannot be overridden. In particular, the -r
command line option no longer has any effect on
dnssec-keygen.
This can be disabled by building with
"configure --disable-crypto-rand".
[RT #31459] [RT #46047]
---
bin/confgen/keygen.c | 12 +++---
bin/dnssec/dnssec-keygen.docbook | 24 +++++++----
bin/dnssec/dnssectool.c | 12 +++---
bin/named/client.c | 3 +-
bin/named/config.c | 4 +-
bin/named/controlconf.c | 19 +++++---
bin/named/include/named/server.h | 2 +
bin/named/interfacemgr.c | 1 +
bin/named/query.c | 1 +
bin/named/server.c | 52 ++++++++++++++--------
bin/nsupdate/nsupdate.c | 4 +-
bin/tests/system/pipelined/pipequeries.c | 4 +-
bin/tests/system/tkey/keycreate.c | 4 +-
bin/tests/system/tkey/keydelete.c | 5 +--
doc/arm/Bv9ARM-book.xml | 55 +++++++++++++++++-------
doc/arm/notes-rh-changes.xml | 42 ++++++++++++++++++
doc/arm/notes.xml | 1 +
lib/dns/dst_api.c | 4 +-
lib/dns/include/dst/dst.h | 14 +++++-
lib/dns/openssl_link.c | 3 +-
lib/isc/include/isc/entropy.h | 48 +++++++++++++++------
lib/isc/include/isc/random.h | 26 +++++++----
lib/isccfg/namedconf.c | 2 +-
23 files changed, 240 insertions(+), 102 deletions(-)
create mode 100644 doc/arm/notes-rh-changes.xml
diff --git a/bin/confgen/keygen.c b/bin/confgen/keygen.c
index bd269e7..1ac775f 100644
--- a/bin/confgen/keygen.c
+++ b/bin/confgen/keygen.c
@@ -161,17 +161,15 @@ generate_key(isc_mem_t *mctx, const char *randomfile, dns_secalg_t alg,
DO("create entropy context", isc_entropy_create(mctx, &ectx));
- if (randomfile != NULL && strcmp(randomfile, "keyboard") == 0) {
- randomfile = NULL;
- open_keyboard = ISC_ENTROPY_KEYBOARDYES;
- }
#ifdef ISC_PLATFORM_CRYPTORANDOM
- if (randomfile != NULL &&
- strcmp(randomfile, ISC_PLATFORM_CRYPTORANDOM) == 0) {
- randomfile = NULL;
+ if (randomfile == NULL) {
isc_entropy_usehook(ectx, true);
}
#endif
+ if (randomfile != NULL && strcmp(randomfile, "keyboard") == 0) {
+ randomfile = NULL;
+ open_keyboard = ISC_ENTROPY_KEYBOARDYES;
+ }
DO("start entropy source", isc_entropy_usebestsource(ectx,
&entropy_source,
randomfile,
diff --git a/bin/dnssec/dnssec-keygen.docbook b/bin/dnssec/dnssec-keygen.docbook
index bd19e1d..2c09b30 100644
--- a/bin/dnssec/dnssec-keygen.docbook
+++ b/bin/dnssec/dnssec-keygen.docbook
@@ -349,15 +349,23 @@
<term>-r <replaceable class="parameter">randomdev</replaceable></term>
<listitem>
<para>
- Specifies the source of randomness. If the operating
- system does not provide a <filename>/dev/random</filename>
- or equivalent device, the default source of randomness
- is keyboard input. <filename>randomdev</filename>
- specifies
+ Specifies a source of randomness. Normally, when generating
+ DNSSEC keys, this option has no effect; the random number
+ generation function provided by the cryptographic library will
+ be used.
+ </para>
+ <para>
+ If that behavior is disabled at compile time, however,
+ the specified file will be used as entropy source
+ for key generation. <filename>randomdev</filename> is
the name of a character device or file containing random
- data to be used instead of the default. The special value
- <filename>keyboard</filename> indicates that keyboard
- input should be used.
+ data to be used. The special value <filename>keyboard</filename>
+ indicates that keyboard input should be used.
+ </para>
+ <para>
+ The default is <filename>/dev/random</filename> if the
+ operating system provides it or an equivalent device;
+ if not, the default source of randomness is keyboard input.
</para>
</listitem>
</varlistentry>
diff --git a/bin/dnssec/dnssectool.c b/bin/dnssec/dnssectool.c
index 2a0f9c6..6fcd411 100644
--- a/bin/dnssec/dnssectool.c
+++ b/bin/dnssec/dnssectool.c
@@ -241,18 +241,16 @@ setup_entropy(isc_mem_t *mctx, const char *randomfile, isc_entropy_t **ectx) {
ISC_LIST_INIT(sources);
}
+#ifdef ISC_PLATFORM_CRYPTORANDOM
+ if (randomfile == NULL) {
+ isc_entropy_usehook(*ectx, true);
+ }
+#endif
if (randomfile != NULL && strcmp(randomfile, "keyboard") == 0) {
usekeyboard = ISC_ENTROPY_KEYBOARDYES;
randomfile = NULL;
}
-#ifdef ISC_PLATFORM_CRYPTORANDOM
- if (randomfile != NULL &&
- strcmp(randomfile, ISC_PLATFORM_CRYPTORANDOM) == 0) {
- randomfile = NULL;
- isc_entropy_usehook(*ectx, true);
- }
-#endif
result = isc_entropy_usebestsource(*ectx, &source, randomfile,
usekeyboard);
diff --git a/bin/named/client.c b/bin/named/client.c
index 4a50ad9..4d140e8 100644
--- a/bin/named/client.c
+++ b/bin/named/client.c
@@ -1768,7 +1768,8 @@ ns_client_addopt(ns_client_t *client, dns_message_t *message,
isc_buffer_init(&buf, cookie, sizeof(cookie));
isc_stdtime_get(&now);
- isc_random_get(&nonce);
+ nonce = ((isc_rng_random(ns_g_server->rngctx) << 16) |
+ isc_rng_random(ns_g_server->rngctx));
compute_cookie(client, now, nonce, ns_g_server->secret, &buf);
diff --git a/bin/named/config.c b/bin/named/config.c
index 9b343fa..5e663c6 100644
--- a/bin/named/config.c
+++ b/bin/named/config.c
@@ -98,7 +98,9 @@ options {\n\
# pid-file \"" NS_LOCALSTATEDIR "/run/named/named.pid\"; /* or /lwresd.pid */\n\
port 53;\n\
prefetch 2 9;\n"
-#ifdef PATH_RANDOMDEV
+#if defined(ISC_PLATFORM_CRYPTORANDOM)
+" random-device none;\n"
+#elif defined(PATH_RANDOMDEV)
" random-device \"" PATH_RANDOMDEV "\";\n"
#endif
" recursing-file \"named.recursing\";\n\
diff --git a/bin/named/controlconf.c b/bin/named/controlconf.c
index 9fdf49b..42128dc 100644
--- a/bin/named/controlconf.c
+++ b/bin/named/controlconf.c
@@ -327,9 +327,10 @@ log_invalid(isccc_ccmsg_t *ccmsg, isc_result_t result) {
static void
control_recvmessage(isc_task_t *task, isc_event_t *event) {
- controlconnection_t *conn;
- controllistener_t *listener;
- controlkey_t *key;
+ controlconnection_t *conn = NULL;
+ controllistener_t *listener = NULL;
+ ns_server_t *server = NULL;
+ controlkey_t *key = NULL;
isccc_sexpr_t *request = NULL;
isccc_sexpr_t *response = NULL;
uint32_t algorithm;
@@ -340,16 +341,17 @@ control_recvmessage(isc_task_t *task, isc_event_t *event) {
isc_buffer_t *text;
isc_result_t result;
isc_result_t eresult;
- isccc_sexpr_t *_ctrl;
+ isccc_sexpr_t *_ctrl = NULL;
isccc_time_t sent;
isccc_time_t exp;
uint32_t nonce;
- isccc_sexpr_t *data;
+ isccc_sexpr_t *data = NULL;
REQUIRE(event->ev_type == ISCCC_EVENT_CCMSG);
conn = event->ev_arg;
listener = conn->listener;
+ server = listener->controls->server;
algorithm = DST_ALG_UNKNOWN;
secret.rstart = NULL;
text = NULL;
@@ -462,8 +464,11 @@ control_recvmessage(isc_task_t *task, isc_event_t *event) {
* Establish nonce.
*/
if (conn->nonce == 0) {
- while (conn->nonce == 0)
- isc_random_get(&conn->nonce);
+ while (conn->nonce == 0) {
+ uint16_t r1 = isc_rng_random(server->rngctx);
+ uint16_t r2 = isc_rng_random(server->rngctx);
+ conn->nonce = (r1 << 16) | r2;
+ }
eresult = ISC_R_SUCCESS;
} else
eresult = ns_control_docommand(request, listener->readonly, &text);
diff --git a/bin/named/include/named/server.h b/bin/named/include/named/server.h
index 4fd0194..0ba2627 100644
--- a/bin/named/include/named/server.h
+++ b/bin/named/include/named/server.h
@@ -20,6 +20,7 @@
#include <isc/log.h>
#include <isc/magic.h>
#include <isc/quota.h>
+#include <isc/random.h>
#include <isc/sockaddr.h>
#include <isc/types.h>
#include <isc/xml.h>
@@ -135,6 +136,7 @@ struct ns_server {
char * lockfile;
uint16_t transfer_tcp_message_size;
+ isc_rng_t * rngctx;
};
struct ns_altsecret {
diff --git a/bin/named/interfacemgr.c b/bin/named/interfacemgr.c
index 93aac31..e12fad9 100644
--- a/bin/named/interfacemgr.c
+++ b/bin/named/interfacemgr.c
@@ -17,6 +17,7 @@
#include <isc/interfaceiter.h>
#include <isc/os.h>
+#include <isc/random.h>
#include <isc/string.h>
#include <isc/task.h>
#include <isc/util.h>
diff --git a/bin/named/query.c b/bin/named/query.c
index 58b5914..edf42d2 100644
--- a/bin/named/query.c
+++ b/bin/named/query.c
@@ -20,6 +20,7 @@
#include <isc/mem.h>
#include <isc/platform.h>
#include <isc/print.h>
+#include <isc/random.h>
#include <isc/rwlock.h>
#include <isc/serial.h>
#include <isc/stats.h>
diff --git a/bin/named/server.c b/bin/named/server.c
index b2ae57c..cca7fe8 100644
--- a/bin/named/server.c
+++ b/bin/named/server.c
@@ -8279,21 +8279,32 @@ load_configuration(const char *filename, ns_server_t *server,
* Open the source of entropy.
*/
if (first_time) {
+ const char *randomdev = NULL;
+ int level = ISC_LOG_ERROR;
obj = NULL;
result = ns_config_get(maps, "random-device", &obj);
- if (result != ISC_R_SUCCESS) {
+ if (result == ISC_R_SUCCESS) {
+ if (!cfg_obj_isvoid(obj)) {
+ level = ISC_LOG_INFO;
+ randomdev = cfg_obj_asstring(obj);
+ }
+ }
+ if (randomdev == NULL) {
+#ifdef ISC_PLATFORM_CRYPTORANDOM
+ isc_entropy_usehook(ns_g_entropy, true);
+#else
+ if ((obj != NULL) && !cfg_obj_isvoid(obj))
+ level = ISC_LOG_INFO;
isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
- NS_LOGMODULE_SERVER, ISC_LOG_INFO,
+ NS_LOGMODULE_SERVER, level,
"no source of entropy found");
+ if ((obj == NULL) || cfg_obj_isvoid(obj)) {
+ CHECK(ISC_R_FAILURE);
+ }
+#endif
} else {
- const char *randomdev = cfg_obj_asstring(obj);
-#ifdef ISC_PLATFORM_CRYPTORANDOM
- if (strcmp(randomdev, ISC_PLATFORM_CRYPTORANDOM) == 0)
- isc_entropy_usehook(ns_g_entropy, true);
-#else
- int level = ISC_LOG_ERROR;
result = isc_entropy_createfilesource(ns_g_entropy,
- randomdev);
+ randomdev);
#ifdef PATH_RANDOMDEV
if (ns_g_fallbackentropy != NULL) {
level = ISC_LOG_INFO;
@@ -8304,8 +8315,8 @@ load_configuration(const char *filename, ns_server_t *server,
NS_LOGCATEGORY_GENERAL,
NS_LOGMODULE_SERVER,
level,
- "could not open entropy source "
- "%s: %s",
+ "could not open "
+ "entropy source %s: %s",
randomdev,
isc_result_totext(result));
}
@@ -8325,7 +8336,6 @@ load_configuration(const char *filename, ns_server_t *server,
}
isc_entropy_detach(&ns_g_fallbackentropy);
}
-#endif
#endif
}
@@ -9097,6 +9107,7 @@ ns_server_create(isc_mem_t *mctx, ns_server_t **serverp) {
server->in_roothints = NULL;
server->blackholeacl = NULL;
server->keepresporder = NULL;
+ server->rngctx = NULL;
/* Must be first. */
CHECKFATAL(dst_lib_init2(ns_g_mctx, ns_g_entropy,
@@ -9123,6 +9134,9 @@ ns_server_create(isc_mem_t *mctx, ns_server_t **serverp) {
CHECKFATAL(dns_tkeyctx_create(ns_g_mctx, ns_g_entropy,
&server->tkeyctx),
"creating TKEY context");
+ server->rngctx = NULL;
+ CHECKFATAL(isc_rng_create(ns_g_mctx, ns_g_entropy, &server->rngctx),
+ "creating random numbers context");
/*
* Setup the server task, which is responsible for coordinating
@@ -9329,7 +9343,8 @@ ns_server_destroy(ns_server_t **serverp) {
if (server->zonemgr != NULL)
dns_zonemgr_detach(&server->zonemgr);
-
+ if (server->rngctx != NULL)
+ isc_rng_detach(&server->rngctx);
if (server->tkeyctx != NULL)
dns_tkeyctx_destroy(&server->tkeyctx);
@@ -13366,10 +13381,10 @@ newzone_cfgctx_destroy(void **cfgp) {
static isc_result_t
generate_salt(unsigned char *salt, size_t saltlen) {
- int i, n;
+ size_t i, n;
union {
unsigned char rnd[256];
- uint32_t rnd32[64];
+ uint16_t rnd16[128];
} rnd;
unsigned char text[512 + 1];
isc_region_t r;
@@ -13379,9 +13394,10 @@ generate_salt(unsigned char *salt, size_t saltlen) {
if (saltlen > 256U)
return (ISC_R_RANGE);
- n = (int) (saltlen + sizeof(uint32_t) - 1) / sizeof(uint32_t);
- for (i = 0; i < n; i++)
- isc_random_get(&rnd.rnd32[i]);
+ n = (saltlen + sizeof(uint16_t) - 1) / sizeof(uint16_t);
+ for (i = 0; i < n; i++) {
+ rnd.rnd16[i] = isc_rng_random(ns_g_server->rngctx);
+ }
memmove(salt, rnd.rnd, saltlen);
diff --git a/bin/nsupdate/nsupdate.c b/bin/nsupdate/nsupdate.c
index 7f15cbc..458aa76 100644
--- a/bin/nsupdate/nsupdate.c
+++ b/bin/nsupdate/nsupdate.c
@@ -289,9 +289,7 @@ setup_entropy(isc_mem_t *mctx, const char *randomfile, isc_entropy_t **ectx) {
}
#ifdef ISC_PLATFORM_CRYPTORANDOM
- if (randomfile != NULL &&
- strcmp(randomfile, ISC_PLATFORM_CRYPTORANDOM) == 0) {
- randomfile = NULL;
+ if (randomfile == NULL) {
isc_entropy_usehook(*ectx, true);
}
#endif
diff --git a/bin/tests/system/pipelined/pipequeries.c b/bin/tests/system/pipelined/pipequeries.c
index 95b65bf..7a81d4e 100644
--- a/bin/tests/system/pipelined/pipequeries.c
+++ b/bin/tests/system/pipelined/pipequeries.c
@@ -280,9 +280,7 @@ main(int argc, char *argv[]) {
ectx = NULL;
RUNCHECK(isc_entropy_create(mctx, &ectx));
#ifdef ISC_PLATFORM_CRYPTORANDOM
- if (randomfile != NULL &&
- strcmp(randomfile, ISC_PLATFORM_CRYPTORANDOM) == 0) {
- randomfile = NULL;
+ if (randomfile == NULL) {
isc_entropy_usehook(ectx, true);
}
#endif
diff --git a/bin/tests/system/tkey/keycreate.c b/bin/tests/system/tkey/keycreate.c
index 3236968..4fa77b6 100644
--- a/bin/tests/system/tkey/keycreate.c
+++ b/bin/tests/system/tkey/keycreate.c
@@ -255,9 +255,7 @@ main(int argc, char *argv[]) {
ectx = NULL;
RUNCHECK(isc_entropy_create(mctx, &ectx));
#ifdef ISC_PLATFORM_CRYPTORANDOM
- if (randomfile != NULL &&
- strcmp(randomfile, ISC_PLATFORM_CRYPTORANDOM) == 0) {
- randomfile = NULL;
+ if (randomfile == NULL) {
isc_entropy_usehook(ectx, true);
}
#endif
diff --git a/bin/tests/system/tkey/keydelete.c b/bin/tests/system/tkey/keydelete.c
index 43fb6b0..105e151 100644
--- a/bin/tests/system/tkey/keydelete.c
+++ b/bin/tests/system/tkey/keydelete.c
@@ -171,6 +171,7 @@ main(int argc, char **argv) {
randomfile = argv[2];
argv += 2;
argc -= 2;
+ POST(argc);
}
keyname = argv[1];
@@ -182,9 +183,7 @@ main(int argc, char **argv) {
ectx = NULL;
RUNCHECK(isc_entropy_create(mctx, &ectx));
#ifdef ISC_PLATFORM_CRYPTORANDOM
- if (randomfile != NULL &&
- strcmp(randomfile, ISC_PLATFORM_CRYPTORANDOM) == 0) {
- randomfile = NULL;
+ if (randomfile == NULL) {
isc_entropy_usehook(ectx, true);
}
#endif
diff --git a/doc/arm/Bv9ARM-book.xml b/doc/arm/Bv9ARM-book.xml
index ca98726..1f9df2c 100644
--- a/doc/arm/Bv9ARM-book.xml
+++ b/doc/arm/Bv9ARM-book.xml
@@ -5034,22 +5034,45 @@ badresp:1,adberr:0,findfail:0,valfail:0]
<term><command>random-device</command></term>
<listitem>
<para>
- This specifies a source of entropy to be used by the server. Entropy is
- primarily needed
- for DNSSEC operations, such as TKEY transactions and dynamic
- update of signed
- zones. This option specifies the device (or file) from which
- to read
- entropy. If it is a file, operations requiring entropy will
- fail when the
- file has been exhausted. If <command>random-device</command> is not specified, the default value
- is
- <filename>/dev/random</filename>
- (or equivalent) when present, and none otherwise. The
- <command>random-device</command> option takes
- effect during
- the initial configuration load at server startup time and
- is ignored on subsequent reloads.
+ Specifies a source of entropy to be used by the server.
+ This is a device or file from which to read entropy.
+ If it is a file, operations requiring entropy
+ will fail when the file has been exhausted.
+ </para>
+ <para>
+ Entropy is needed for cryptographic operations such as
+ TKEY transactions, dynamic update of signed zones, and
+ generation of TSIG session keys. It is also used for
+ seeding and stirring the pseudo-random number generator,
+ which is used for less critical functions requiring
+ randomness such as generation of DNS message transaction
+ ID's.
+ </para>
+ <para>
+ If <command>random-device</command> is not specified, or
+ if it is set to <literal>none</literal>, entropy will be
+ read from the random number generation function supplied
+ by the cryptographic library with which BIND was linked
+ (i.e. OpenSSL or a PKCS#11 provider).
+ </para>
+ <para>
+ The <command>random-device</command> option takes
+ effect during the initial configuration load at server
+ startup time and is ignored on subsequent reloads.
+ </para>
+ <para>
+ If BIND is built with
+ <command>configure --disable-crypto-rand</command>, then
+ entropy is <emphasis>not</emphasis> sourced from the
+ cryptographic library. In this case, if
+ <command>random-device</command> is not specified, the
+ default value is the system random device,
+ <filename>/dev/random</filename> or the equivalent.
+ This default can be overridden with
+ <command>configure --with-randomdev</command>.
+ If no system random device exists, then no entropy source
+ will be configured, and <command>named</command> will only
+ be able to use pseudo-random numbers.
</para>
</listitem>
</varlistentry>
diff --git a/doc/arm/notes-rh-changes.xml b/doc/arm/notes-rh-changes.xml
new file mode 100644
index 0000000..89a4961
--- /dev/null
+++ b/doc/arm/notes-rh-changes.xml
@@ -0,0 +1,42 @@
+<!--
+ - Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ -
+ - This Source Code Form is subject to the terms of the Mozilla Public
+ - License, v. 2.0. If a copy of the MPL was not distributed with this
+ - file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ -
+ - See the COPYRIGHT file distributed with this work for additional
+ - information regarding copyright ownership.
+-->
+
+<section xml:id="relnotes_rh_changes"><info><title>Red Hat Specific Changes</title></info>
+ <itemizedlist>
+ <listitem>
+ <para>
+ By default, BIND now uses the random number generation functions
+ in the cryptographic library (i.e., OpenSSL or a PKCS#11
+ provider) as a source of high-quality randomness rather than
+ <filename>/dev/random</filename>. This is suitable for virtual
+ machine environments, which may have limited entropy pools and
+ lack hardware random number generators.
+ </para>
+ <para>
+ This can be overridden by specifying another entropy source via
+ the <command>random-device</command> option in
+ <filename>named.conf</filename>, or via the <command>-r</command>
+ command line option. However, for functions requiring full
+ cryptographic strength, such as DNSSEC key generation, this
+ <emphasis>cannot</emphasis> be overridden. In particular, the
+ <command>-r</command> command line option no longer has any
+ effect on <command>dnssec-keygen</command>.
+ </para>
+ <para>
+ This can be disabled by building with
+ <command>configure --disable-crypto-rand</command>, in which
+ case <filename>/dev/random</filename> will be the default
+ entropy source. [RT #31459] [RT #46047]
+ </para>
+ </listitem>
+ </itemizedlist>
+</section>
+
diff --git a/doc/arm/notes.xml b/doc/arm/notes.xml
index a5e42c0..f8cb1f9 100644
--- a/doc/arm/notes.xml
+++ b/doc/arm/notes.xml
@@ -47,6 +47,7 @@
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="notes-9.11.1.xml"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="notes-9.11.0.xml"/>
+ <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="notes-rh-changes.xml"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="notes-eol.xml"/>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="notes-thankyou.xml"/>
</section>
diff --git a/lib/dns/dst_api.c b/lib/dns/dst_api.c
index aa54afc..2156384 100644
--- a/lib/dns/dst_api.c
+++ b/lib/dns/dst_api.c
@@ -2017,10 +2017,12 @@ dst__entropy_getdata(void *buf, unsigned int len, bool pseudo) {
else
flags |= ISC_ENTROPY_BLOCKING;
#ifdef ISC_PLATFORM_CRYPTORANDOM
+ /* get entropy directly from crypto provider */
return (dst_random_getdata(buf, len, NULL, flags));
#else
+ /* get entropy from entropy source or hook function */
return (isc_entropy_getdata(dst_entropy_pool, buf, len, NULL, flags));
-#endif
+#endif /* ISC_PLATFORM_CRYPTORANDOM */
#endif /* PKCS11CRYPTO */
}
diff --git a/lib/dns/include/dst/dst.h b/lib/dns/include/dst/dst.h
index 3aba028..180c841 100644
--- a/lib/dns/include/dst/dst.h
+++ b/lib/dns/include/dst/dst.h
@@ -163,8 +163,18 @@ isc_result_t
dst_random_getdata(void *data, unsigned int length,
unsigned int *returned, unsigned int flags);
/*%<
- * \brief Return data from the crypto random generator.
- * Specialization of isc_entropy_getdata().
+ * Gets random data from the random generator provided by the
+ * crypto library, if BIND was built with --enable-crypto-rand.
+ *
+ * See isc_entropy_getdata() for parameter usage. Normally when
+ * this function is available, it will be set up as a hook in the
+ * entropy context, so that isc_entropy_getdata() is a front-end to
+ * this function.
+ *
+ * Returns:
+ * \li ISC_R_SUCCESS on success
+ * \li ISC_R_NOTIMPLEMENTED if BIND is built with --disable-crypto-rand
+ * \li DST_R_OPENSSLFAILURE, DST_R_CRYPTOFAILURE, or other codes on error
*/
bool
diff --git a/lib/dns/openssl_link.c b/lib/dns/openssl_link.c
index 3f4f822..cfdc757 100644
--- a/lib/dns/openssl_link.c
+++ b/lib/dns/openssl_link.c
@@ -484,7 +484,8 @@ dst__openssl_getengine(const char *engine) {
isc_result_t
dst_random_getdata(void *data, unsigned int length,
- unsigned int *returned, unsigned int flags) {
+ unsigned int *returned, unsigned int flags)
+{
#ifdef ISC_PLATFORM_CRYPTORANDOM
#ifndef DONT_REQUIRE_DST_LIB_INIT
INSIST(dst__memory_pool != NULL);
diff --git a/lib/isc/include/isc/entropy.h b/lib/isc/include/isc/entropy.h
index f32c9dc..bed276b 100644
--- a/lib/isc/include/isc/entropy.h
+++ b/lib/isc/include/isc/entropy.h
@@ -189,9 +189,8 @@ isc_entropy_createcallbacksource(isc_entropy_t *ent,
/*!<
* \brief Create an entropy source that is polled via a callback.
*
- * This would
- * be used when keyboard input is used, or a GUI input method. It can
- * also be used to hook in any external entropy source.
+ * This would be used when keyboard input is used, or a GUI input method.
+ * It can also be used to hook in any external entropy source.
*
* Samples are added via isc_entropy_addcallbacksample(), below.
* _addcallbacksample() is the only function which may be called from
@@ -232,15 +231,32 @@ isc_result_t
isc_entropy_getdata(isc_entropy_t *ent, void *data, unsigned int length,
unsigned int *returned, unsigned int flags);
/*!<
- * \brief Extract data from the entropy pool. This may load the pool from various
- * sources.
+ * \brief Get random data from entropy pool 'ent'.
*
- * Do this by stirring the pool and returning a part of hash as randomness.
- * Note that no secrets are given away here since parts of the hash are
- * xored together before returned.
+ * If a hook has been set up using isc_entropy_sethook() and
+ * isc_entropy_usehook(), then the hook function will be called to get
+ * random data.
*
- * Honor the request from the caller to only return good data, any data,
- * etc.
+ * Otherwise, randomness is extracted from the entropy pool set up in BIND.
+ * This may cause the pool to be loaded from various sources. Ths is done
+ * by stirring the pool and returning a part of hash as randomness.
+ * (Note that no secrets are given away here since parts of the hash are
+ * XORed together before returning.)
+ *
+ * 'flags' may contain ISC_ENTROPY_GOODONLY, ISC_ENTROPY_PARTIAL, or
+ * ISC_ENTROPY_BLOCKING. These will be honored if the hook function is
+ * not in use. If it is, the flags will be passed to the hook function
+ * but it may ignore them.
+ *
+ * Up to 'length' bytes of randomness are retrieved and copied into 'data'.
+ * (If 'returned' is not NULL, and the number of bytes copied is less than
+ * 'length' - which may happen if ISC_ENTROPY_PARTIAL was used - then the
+ * number of bytes copied will be stored in *returned.)
+ *
+ * Returns:
+ * \li ISC_R_SUCCESS on success
+ * \li ISC_R_NOENTROPY if entropy pool is empty
+ * \li other error codes are possible when a hook is in use
*/
void
@@ -305,13 +321,21 @@ isc_entropy_usebestsource(isc_entropy_t *ectx, isc_entropysource_t **source,
void
isc_entropy_usehook(isc_entropy_t *ectx, bool onoff);
/*!<
- * \brief Mark/unmark the given entropy structure as being hooked.
+ * \brief Configure entropy context 'ectx' to use the hook function
+ *
+ * Sets the entropy context to call the hook function for random number
+ * generation, if such a function has been configured via
+ * isc_entropy_sethook(), whenever isc_entropy_getdata() is called.
*/
void
isc_entropy_sethook(isc_entropy_getdata_t myhook);
/*!<
- * \brief Set the getdata hook (e.g., for a crypto random generator).
+ * \brief Set the hook function.
+ *
+ * The hook function is a global value: only one hook function
+ * can be set in the system. Individual entropy contexts may be
+ * configured to use it, or not, by calling isc_entropy_usehook().
*/
ISC_LANG_ENDDECLS
diff --git a/lib/isc/include/isc/random.h b/lib/isc/include/isc/random.h
index f38e80d..3cb1c56 100644
--- a/lib/isc/include/isc/random.h
+++ b/lib/isc/include/isc/random.h
@@ -19,13 +19,23 @@
#include <isc/mutex.h>
/*! \file isc/random.h
- * \brief Implements a random state pool which will let the caller return a
- * series of possibly non-reproducible random values.
+ * \brief Implements pseudo random number generators.
*
- * Note that the
- * strength of these numbers is not all that high, and should not be
- * used in cryptography functions. It is useful for jittering values
- * a bit here and there, such as timeouts, etc.
+ * Two pseudo-random number generators are implemented, in isc_random_*
+ * and isc_rng_*. Neither one is very strong; they should not be used
+ * in cryptography functions.
+ *
+ * isc_random_* is based on arc4random if it is available on the system.
+ * Otherwise it is based on the posix srand() and rand() functions.
+ * It is useful for jittering values a bit here and there, such as
+ * timeouts, etc, but should not be relied upon to generate
+ * unpredictable sequences (for example, when choosing transaction IDs).
+ *
+ * isc_rng_* is based on ChaCha20, and is seeded and stirred from the
+ * system entropy source. It is stronger than isc_random_* and can
+ * be used for generating unpredictable sequences. It is still not as
+ * good as using system entropy directly (see entropy.h) and should not
+ * be used for cryptographic functions such as key generation.
*/
ISC_LANG_BEGINDECLS
@@ -113,8 +123,8 @@ isc_rng_random(isc_rng_t *rngctx);
uint16_t
isc_rng_uniformrandom(isc_rng_t *rngctx, uint16_t upper_bound);
/*%<
- * Returns a uniformly distributed pseudo random 16-bit unsigned
- * integer.
+ * Returns a uniformly distributed pseudo-random 16-bit unsigned integer
+ * less than 'upper_bound'.
*/
ISC_LANG_ENDDECLS
diff --git a/lib/isccfg/namedconf.c b/lib/isccfg/namedconf.c
index e74c93b..212194e 100644
--- a/lib/isccfg/namedconf.c
+++ b/lib/isccfg/namedconf.c
@@ -1109,7 +1109,7 @@ options_clauses[] = {
{ "pid-file", &cfg_type_qstringornone, 0 },
{ "port", &cfg_type_uint32, 0 },
{ "querylog", &cfg_type_boolean, 0 },
- { "random-device", &cfg_type_qstring, 0 },
+ { "random-device", &cfg_type_qstringornone, 0 },
{ "recursing-file", &cfg_type_qstring, 0 },
{ "recursive-clients", &cfg_type_uint32, 0 },
{ "reserved-sockets", &cfg_type_uint32, 0 },
--
2.26.2