rdelaage
/
postgresql
mirror of https://git.postgresql.org/git/postgresql.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Revert "Replace PostmasterRandom() with a stronger way of generating randomness." 

This reverts commit 9e083fd468. That was a
few bricks shy of a load:

* Query cancel stopped working
* Buildfarm member pademelon stopped working, because the box doesn't have
  /dev/urandom nor /dev/random.

This clearly needs some more discussion, and a quite different patch, so
revert for now.
This commit is contained in:
Heikki Linnakangas 2016-10-18 16:28:23 +03:00
parent 7d3235ba42
commit faae1c918e
9 changed files with 383 additions and 243 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
contrib/pgcrypto/Makefile
View File

@ -1,7 +1,7 @@
# contrib/pgcrypto/Makefile
INT_SRCS = md5.c sha1.c sha2.c internal.c internal-sha2.c blf.c rijndael.c \
fortuna.c pgp-mpi-internal.c imath.c
fortuna.c random.c pgp-mpi-internal.c imath.c
INT_TESTS = sha2
OSSL_SRCS = openssl.c pgp-mpi-openssl.c

36
contrib/pgcrypto/internal.c
View File

@ -626,6 +626,8 @@ static time_t check_time = 0;
static void
system_reseed(void)
{
uint8 buf[1024];
int n;
time_t t;
int skip = 1;
@ -640,34 +642,24 @@ system_reseed(void)
else if (check_time == 0 ||
(t - check_time) > SYSTEM_RESEED_CHECK_TIME)
{
uint8 buf;
check_time = t;
/* roll dice */
px_get_random_bytes(&buf, 1);
skip = (buf >= SYSTEM_RESEED_CHANCE);
/* clear 1 byte */
px_memset(&buf, 0, sizeof(buf));
px_get_random_bytes(buf, 1);
skip = buf[0] >= SYSTEM_RESEED_CHANCE;
}
if (!skip)
{
/*
* fortuna_add_entropy passes the input to SHA-256, so there's no
* point in giving it more than 256 bits of input to begin with.
*/
uint8 buf[32];
/* clear 1 byte */
px_memset(buf, 0, sizeof(buf));
if (!pg_strong_random(buf, sizeof(buf)))
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("could not acquire random data")));
fortuna_add_entropy(buf, sizeof(buf));
if (skip)
return;
seed_time = t;
px_memset(buf, 0, sizeof(buf));
}
n = px_acquire_system_randomness(buf);
if (n > 0)
fortuna_add_entropy(buf, n);
seed_time = t;
px_memset(buf, 0, sizeof(buf));
}
int

247
contrib/pgcrypto/random.c Normal file
View File

@ -0,0 +1,247 @@
/*
* random.c
* Acquire randomness from system. For seeding RNG.
*
* Copyright (c) 2001 Marko Kreen
* 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.
* 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
*
* contrib/pgcrypto/random.c
*/
#include "postgres.h"
#include "px.h"
#include "utils/memdebug.h"
/* how many bytes to ask from system random provider */
#define RND_BYTES 32
/*
* Try to read from /dev/urandom or /dev/random on these OS'es.
*
* The list can be pretty liberal, as the device not existing
* is expected event.
*/
#if defined(__linux__) || defined(__FreeBSD__) || defined(__OpenBSD__) \
|| defined(__NetBSD__) || defined(__DragonFly__) \
|| defined(__darwin__) || defined(__SOLARIS__) \
|| defined(__hpux) || defined(__HPUX__) \
|| defined(__CYGWIN__) || defined(_AIX)
#define TRY_DEV_RANDOM
#include <fcntl.h>
#include <unistd.h>
static int
safe_read(int fd, void *buf, size_t count)
{
int done = 0;
char *p = buf;
int res;
while (count)
{
res = read(fd, p, count);
if (res <= 0)
{
if (errno == EINTR)
continue;
return PXE_DEV_READ_ERROR;
}
p += res;
done += res;
count -= res;
}
return done;
}
static uint8 *
try_dev_random(uint8 *dst)
{
int fd;
int res;
fd = open("/dev/urandom", O_RDONLY, 0);
if (fd == -1)
{
fd = open("/dev/random", O_RDONLY, 0);
if (fd == -1)
return dst;
}
res = safe_read(fd, dst, RND_BYTES);
close(fd);
if (res > 0)
dst += res;
return dst;
}
#endif
/*
* Try to find randomness on Windows
*/
#ifdef WIN32
#define TRY_WIN32_GENRAND
#define TRY_WIN32_PERFC
#include <windows.h>
#include <wincrypt.h>
/*
* this function is from libtomcrypt
*
* try to use Microsoft crypto API
*/
static uint8 *
try_win32_genrand(uint8 *dst)
{
int res;
HCRYPTPROV h = 0;
res = CryptAcquireContext(&h, NULL, MS_DEF_PROV, PROV_RSA_FULL,
(CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET));
if (!res)
res = CryptAcquireContext(&h, NULL, MS_DEF_PROV, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET | CRYPT_NEWKEYSET);
if (!res)
return dst;
res = CryptGenRandom(h, RND_BYTES, dst);
if (res == TRUE)
dst += RND_BYTES;
CryptReleaseContext(h, 0);
return dst;
}
static uint8 *
try_win32_perfc(uint8 *dst)
{
int res;
LARGE_INTEGER time;
res = QueryPerformanceCounter(&time);
if (!res)
return dst;
memcpy(dst, &time, sizeof(time));
return dst + sizeof(time);
}
#endif /* WIN32 */
/*
* If we are not on Windows, then hopefully we are
* on a unix-like system. Use the usual suspects
* for randomness.
*/
#ifndef WIN32
#define TRY_UNIXSTD
#include <sys/types.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>
/*
* Everything here is predictible, only needs some patience.
*
* But there is a chance that the system-specific functions
* did not work. So keep faith and try to slow the attacker down.
*/
static uint8 *
try_unix_std(uint8 *dst)
{
pid_t pid;
int x;
PX_MD *md;
struct timeval tv;
int res;
/* process id */
pid = getpid();
memcpy(dst, (uint8 *) &pid, sizeof(pid));
dst += sizeof(pid);
/* time */
gettimeofday(&tv, NULL);
memcpy(dst, (uint8 *) &tv, sizeof(tv));
dst += sizeof(tv);
/* pointless, but should not hurt */
x = random();
memcpy(dst, (uint8 *) &x, sizeof(x));
dst += sizeof(x);
/* hash of uninitialized stack and heap allocations */
res = px_find_digest("sha1", &md);
if (res >= 0)
{
uint8 *ptr;
uint8 stack[8192];
int alloc = 32 * 1024;
VALGRIND_MAKE_MEM_DEFINED(stack, sizeof(stack));
px_md_update(md, stack, sizeof(stack));
ptr = px_alloc(alloc);
VALGRIND_MAKE_MEM_DEFINED(ptr, alloc);
px_md_update(md, ptr, alloc);
px_free(ptr);
px_md_finish(md, dst);
px_md_free(md);
dst += 20;
}
return dst;
}
#endif
/*
* try to extract some randomness for initial seeding
*
* dst should have room for 1024 bytes.
*/
unsigned
px_acquire_system_randomness(uint8 *dst)
{
uint8 *p = dst;
#ifdef TRY_DEV_RANDOM
p = try_dev_random(p);
#endif
#ifdef TRY_WIN32_GENRAND
p = try_win32_genrand(p);
#endif
#ifdef TRY_WIN32_PERFC
p = try_win32_perfc(p);
#endif
#ifdef TRY_UNIXSTD
p = try_unix_std(p);
#endif
return p - dst;
}

27
src/backend/libpq/auth.c
View File

@ -45,12 +45,6 @@ static void auth_failed(Port *port, int status, char *logdetail);
static char *recv_password_packet(Port *port);
static int recv_and_check_password_packet(Port *port, char **logdetail);
/*----------------------------------------------------------------
* MD5 authentication
*----------------------------------------------------------------
*/
static int CheckMD5Auth(Port *port, char **logdetail);
/*----------------------------------------------------------------
* Ident authentication
@ -541,7 +535,9 @@ ClientAuthentication(Port *port)
ereport(FATAL,
(errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
errmsg("MD5 authentication is not supported when \"db_user_namespace\" is enabled")));
status = CheckMD5Auth(port, &logdetail);
/* include the salt to use for computing the response */
sendAuthRequest(port, AUTH_REQ_MD5, port->md5Salt, 4);
status = recv_and_check_password_packet(port, &logdetail);
break;
case uaPassword:
@ -696,25 +692,10 @@ recv_password_packet(Port *port)
/*----------------------------------------------------------------
* MD5 and password authentication
* MD5 authentication
*----------------------------------------------------------------
*/
static int
CheckMD5Auth(Port *port, char **logdetail)
{
/* include the salt to use for computing the response */
if (!pg_strong_random(port->md5Salt, sizeof(port->md5Salt)))
{
*logdetail = psprintf(_("Could not generate random salt"));
return STATUS_ERROR;
}
sendAuthRequest(port, AUTH_REQ_MD5, port->md5Salt, 4);
return recv_and_check_password_packet(port, logdetail);
}
/*
* Called when we have sent an authorization request for a password.
* Get the response and check it.

155
src/backend/postmaster/postmaster.c
View File

@ -358,6 +358,14 @@ static volatile bool avlauncher_needs_signal = false;
static volatile bool StartWorkerNeeded = true;
static volatile bool HaveCrashedWorker = false;
/*
* State for assigning random salts and cancel keys.
* Also, the global MyCancelKey passes the cancel key assigned to a given
* backend from the postmaster to that backend (via fork).
*/
static unsigned int random_seed = 0;
static struct timeval random_start_time;
#ifdef USE_BONJOUR
static DNSServiceRef bonjour_sdref = NULL;
#endif
@ -395,6 +403,8 @@ static void processCancelRequest(Port *port, void *pkt);
static int initMasks(fd_set *rmask);
static void report_fork_failure_to_client(Port *port, int errnum);
static CAC_state canAcceptConnections(void);
static long PostmasterRandom(void);
static void RandomSalt(char *salt, int len);
static void signal_child(pid_t pid, int signal);
static bool SignalSomeChildren(int signal, int targets);
static void TerminateChildren(int signal);
@ -569,11 +579,9 @@ PostmasterMain(int argc, char *argv[])
* Initialize random(3) so we don't get the same values in every run.
*
* Note: the seed is pretty predictable from externally-visible facts such
* as postmaster start time, so don't use random() for security-critical
* random values (use pg_strong_random() instead). Backends select a
* somewhat more random seed after forking, in BackendRun(), based on the
* PID and session start timestamp, but that is still not suitable for
* security-critical values.
* as postmaster start time, so avoid using random() for security-critical
* random values during postmaster startup. At the time of first
* connection, PostmasterRandom will select a hopefully-more-random seed.
*/
srandom((unsigned int) (MyProcPid ^ MyStartTime));
@ -1284,6 +1292,8 @@ PostmasterMain(int argc, char *argv[])
* Remember postmaster startup time
*/
PgStartTime = GetCurrentTimestamp();
/* PostmasterRandom wants its own copy */
gettimeofday(&random_start_time, NULL);
/*
* We're ready to rock and roll...
@ -2333,6 +2343,15 @@ ConnCreate(int serverFd)
return NULL;
}
/*
* Precompute password salt values to use for this connection. It's
* slightly annoying to do this long in advance of knowing whether we'll
* need 'em or not, but we must do the random() calls before we fork, not
* after. Else the postmaster's random sequence won't get advanced, and
* all backends would end up using the same salt...
*/
RandomSalt(port->md5Salt, sizeof(port->md5Salt));
/*
* Allocate GSSAPI specific state struct
*/
@ -3885,12 +3904,7 @@ BackendStartup(Port *port)
* backend will have its own copy in the forked-off process' value of
* MyCancelKey, so that it can transmit the key to the frontend.
*/
if (!pg_strong_random(&MyCancelKey, sizeof(MyCancelKey)))
{
ereport(LOG,
(errmsg("could not generate random query cancel key")));
return STATUS_ERROR;
}
MyCancelKey = PostmasterRandom();
bn->cancel_key = MyCancelKey;
/* Pass down canAcceptConnections state */
@ -4198,6 +4212,13 @@ BackendRun(Port *port)
int usecs;
int i;
/*
* Don't want backend to be able to see the postmaster random number
* generator state. We have to clobber the static random_seed *and* start
* a new random sequence in the random() library function.
*/
random_seed = 0;
random_start_time.tv_usec = 0;
/* slightly hacky way to convert timestamptz into integers */
TimestampDifference(0, port->SessionStartTime, &secs, &usecs);
srandom((unsigned int) (MyProcPid ^ (usecs << 12) ^ secs));
@ -5045,6 +5066,66 @@ StartupPacketTimeoutHandler(void)
}
/*
* RandomSalt
*/
static void
RandomSalt(char *salt, int len)
{
long rand;
int i;
/*
* We use % 255, sacrificing one possible byte value, so as to ensure that
* all bits of the random() value participate in the result. While at it,
* add one to avoid generating any null bytes.
*/
for (i = 0; i < len; i++)
{
rand = PostmasterRandom();
salt[i] = (rand % 255) + 1;
}
}
/*
* PostmasterRandom
*
* Caution: use this only for values needed during connection-request
* processing. Otherwise, the intended property of having an unpredictable
* delay between random_start_time and random_stop_time will be broken.
*/
static long
PostmasterRandom(void)
{
/*
* Select a random seed at the time of first receiving a request.
*/
if (random_seed == 0)
{
do
{
struct timeval random_stop_time;
gettimeofday(&random_stop_time, NULL);
/*
* We are not sure how much precision is in tv_usec, so we swap
* the high and low 16 bits of 'random_stop_time' and XOR them
* with 'random_start_time'. On the off chance that the result is
* 0, we loop until it isn't.
*/
random_seed = random_start_time.tv_usec ^
((random_stop_time.tv_usec << 16) |
((random_stop_time.tv_usec >> 16) & 0xffff));
}
while (random_seed == 0);
srandom(random_seed);
}
return random();
}
/*
* Count up number of child processes of specified types (dead_end chidren
* are always excluded).
@ -5222,37 +5303,31 @@ StartAutovacuumWorker(void)
* we'd better have something random in the field to prevent
* unfriendly people from sending cancels to them.
*/
if (pg_strong_random(&MyCancelKey, sizeof(MyCancelKey)))
MyCancelKey = PostmasterRandom();
bn->cancel_key = MyCancelKey;
/* Autovac workers are not dead_end and need a child slot */
bn->dead_end = false;
bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot();
bn->bgworker_notify = false;
bn->pid = StartAutoVacWorker();
if (bn->pid > 0)
{
bn->cancel_key = MyCancelKey;
/* Autovac workers are not dead_end and need a child slot */
bn->dead_end = false;
bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot();
bn->bgworker_notify = false;
bn->pid = StartAutoVacWorker();
if (bn->pid > 0)
{
bn->bkend_type = BACKEND_TYPE_AUTOVAC;
dlist_push_head(&BackendList, &bn->elem);
bn->bkend_type = BACKEND_TYPE_AUTOVAC;
dlist_push_head(&BackendList, &bn->elem);
#ifdef EXEC_BACKEND
ShmemBackendArrayAdd(bn);
ShmemBackendArrayAdd(bn);
#endif
/* all OK */
return;
}
/*
* fork failed, fall through to report -- actual error message
* was logged by StartAutoVacWorker
*/
(void) ReleasePostmasterChildSlot(bn->child_slot);
/* all OK */
return;
}
else
ereport(LOG,
(errmsg("could not generate random query cancel key")));
/*
* fork failed, fall through to report -- actual error message was
* logged by StartAutoVacWorker
*/
(void) ReleasePostmasterChildSlot(bn->child_slot);
free(bn);
}
else
@ -5540,11 +5615,7 @@ assign_backendlist_entry(RegisteredBgWorker *rw)
* have something random in the field to prevent unfriendly people from
* sending cancels to them.
*/
if (!pg_strong_random(&MyCancelKey, sizeof(MyCancelKey)))
{
rw->rw_crashed_at = GetCurrentTimestamp();
return false;
}
MyCancelKey = PostmasterRandom();
bn->cancel_key = MyCancelKey;
bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot();

3
src/include/port.h
View File

@ -454,9 +454,6 @@ extern int pg_codepage_to_encoding(UINT cp);
extern char *inet_net_ntop(int af, const void *src, int bits,
char *dst, size_t size);
/* port/pg_strong_random.c */
extern bool pg_strong_random(void *buf, size_t len);
/* port/pgcheckdir.c */
extern int pg_check_dir(const char *dir);

2
src/port/Makefile
View File

@ -32,7 +32,7 @@ LIBS += $(PTHREAD_LIBS)
OBJS = $(LIBOBJS) $(PG_CRC32C_OBJS) chklocale.o erand48.o inet_net_ntop.o \
noblock.o path.o pgcheckdir.o pgmkdirp.o pgsleep.o \
pg_strong_random.o pgstrcasecmp.o pqsignal.o \
pgstrcasecmp.o pqsignal.o \
qsort.o qsort_arg.o quotes.o sprompt.o tar.o thread.o
# foo_srv.o and foo.o are both built from foo.c, but only foo.o has -DFRONTEND

148
src/port/pg_strong_random.c
View File

@ -1,148 +0,0 @@
/*-------------------------------------------------------------------------
*
* pg_strong_random.c
* pg_strong_random() function to return a strong random number
*
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
*
*
* IDENTIFICATION
* src/port/pg_strong_random.c
*
*-------------------------------------------------------------------------
*/
#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif
#include <fcntl.h>
#include <unistd.h>
#ifdef USE_SSL
#include <openssl/rand.h>
#endif
#ifdef WIN32
#include <Wincrypt.h>
#endif
static bool random_from_file(char *filename, void *buf, size_t len);
#ifdef WIN32
/*
* Cache a global crypto provider that only gets freed when the process
* exits, in case we need random numbers more than once.
*/
static HCRYPTPROV hProvider = 0;
#endif
/*
* Read (random) bytes from a file.
*/
static bool
random_from_file(char *filename, void *buf, size_t len)
{
int f;
char *p = buf;
ssize_t res;
f = open(filename, O_RDONLY, 0);
if (f == -1)
return false;
while (len)
{
res = read(f, p, len);
if (res <= 0)
{
if (errno == EINTR)
continue; /* interrupted by signal, just retry */
close(f);
return false;
}
p += res;
len -= res;
}
close(f);
return true;
}
/*
* pg_strong_random
*
* Generate requested number of random bytes. The bytes are
* cryptographically strong random, suitable for use e.g. in key
* generation.
*
* The bytes can be acquired from a number of sources, depending
* on what's available. We try the following, in this order:
*
* 1. OpenSSL's RAND_bytes()
* 2. Windows' CryptGenRandom() function
* 3. /dev/urandom
* 4. /dev/random
*
* Returns true on success, and false if none of the sources
* were available. NB: It is important to check the return value!
* Proceeding with key generation when no random data was available
* would lead to predictable keys and security issues.
*/
bool
pg_strong_random(void *buf, size_t len)
{
#ifdef USE_SSL
/*
* When built with OpenSSL, first try the random generation function from
* there.
*/
if (RAND_bytes(buf, len) == 1)
return true;
#endif
#ifdef WIN32
/*
* Windows has CryptoAPI for strong cryptographic numbers.
*/
if (hProvider == 0)
{
if (!CryptAcquireContext(&hProvider,
NULL,
MS_DEF_PROV,
PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT | CRYPT_SILENT))
{
/*
* On failure, set back to 0 in case the value was for some reason
* modified.
*/
hProvider = 0;
}
}
/* Re-check in case we just retrieved the provider */
if (hProvider != 0)
{
if (CryptGenRandom(hProvider, len, buf))
return true;
}
#endif
/*
* If there is no OpenSSL and no CryptoAPI (or they didn't work), then
* fall back on reading /dev/urandom or even /dev/random.
*/
if (random_from_file("/dev/urandom", buf, len))
return true;
if (random_from_file("/dev/random", buf, len))
return true;
/* None of the sources were available. */
return false;
}

6
src/tools/msvc/Mkvcbuild.pm
View File

@ -92,7 +92,7 @@ sub mkvcbuild
srandom.c getaddrinfo.c gettimeofday.c inet_net_ntop.c kill.c open.c
erand48.c snprintf.c strlcat.c strlcpy.c dirmod.c noblock.c path.c
pgcheckdir.c pgmkdirp.c pgsleep.c pgstrcasecmp.c pqsignal.c
mkdtemp.c pg_strong_random.c qsort.c qsort_arg.c quotes.c system.c
mkdtemp.c qsort.c qsort_arg.c quotes.c system.c
sprompt.c tar.c thread.c getopt.c getopt_long.c dirent.c
win32env.c win32error.c win32security.c win32setlocale.c);
@ -425,8 +425,8 @@ sub mkvcbuild
'sha1.c', 'sha2.c',
'internal.c', 'internal-sha2.c',
'blf.c', 'rijndael.c',
'fortuna.c', 'pgp-mpi-internal.c',
'imath.c');
'fortuna.c', 'random.c',
'pgp-mpi-internal.c', 'imath.c');
}
$pgcrypto->AddReference($postgres);
$pgcrypto->AddLibrary('ws2_32.lib');