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Replace PostmasterRandom() with a stronger source, second attempt.
This adds a new routine, pg_strong_random() for generating random bytes, for use in both frontend and backend. At the moment, it's only used in the backend, but the upcoming SCRAM authentication patches need strong random numbers in libpq as well. pg_strong_random() is based on, and replaces, the existing implementation in pgcrypto. It can acquire strong random numbers from a number of sources, depending on what's available: - OpenSSL RAND_bytes(), if built with OpenSSL - On Windows, the native cryptographic functions are used - /dev/urandom Unlike the current pgcrypto function, the source is chosen by configure. That makes it easier to test different implementations, and ensures that we don't accidentally fall back to a less secure implementation, if the primary source fails. All of those methods are quite reliable, it would be pretty surprising for them to fail, so we'd rather find out by failing hard. If no strong random source is available, we fall back to using erand48(), seeded from current timestamp, like PostmasterRandom() was. That isn't cryptographically secure, but allows us to still work on platforms that don't have any of the above stronger sources. Because it's not very secure, the built-in implementation is only used if explicitly requested with --disable-strong-random. This replaces the more complicated Fortuna algorithm we used to have in pgcrypto, which is unfortunate, but all modern platforms have /dev/urandom, so it doesn't seem worth the maintenance effort to keep that. pgcrypto functions that require strong random numbers will be disabled with --disable-strong-random. Original patch by Magnus Hagander, tons of further work by Michael Paquier and me. Discussion: https://www.postgresql.org/message-id/CAB7nPqRy3krN8quR9XujMVVHYtXJ0_60nqgVc6oUk8ygyVkZsA@mail.gmail.com Discussion: https://www.postgresql.org/message-id/CAB7nPqRWkNYRRPJA7-cF+LfroYV10pvjdz6GNvxk-Eee9FypKA@mail.gmail.com
This commit is contained in:
Heikki Linnakangas
109
configure
vendored
109
configure
vendored
@ -739,6 +739,7 @@ GENHTML
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LCOV
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GCOV
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enable_debug
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enable_strong_random
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enable_rpath
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default_port
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WANTED_LANGUAGES
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@ -806,6 +807,7 @@ with_pgport
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enable_rpath
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enable_spinlocks
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enable_atomics
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enable_strong_random
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enable_debug
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enable_profiling
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enable_coverage
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@ -1478,6 +1480,7 @@ Optional Features:
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executables
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--disable-spinlocks do not use spinlocks
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--disable-atomics do not use atomic operations
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--disable-strong-random do not use a strong random number source
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--enable-debug build with debugging symbols (-g)
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--enable-profiling build with profiling enabled
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--enable-coverage build with coverage testing instrumentation
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@ -3192,6 +3195,34 @@ fi
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#
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# Random number generation
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#
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# Check whether --enable-strong-random was given.
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if test "${enable_strong_random+set}" = set; then :
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enableval=$enable_strong_random;
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case $enableval in
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yes)
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:
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;;
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no)
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:
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;;
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*)
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as_fn_error $? "no argument expected for --enable-strong-random option" "$LINENO" 5
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;;
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esac
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else
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enable_strong_random=yes
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fi
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#
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# --enable-debug adds -g to compiler flags
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#
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@ -14982,6 +15013,84 @@ $as_echo "#define USE_WIN32_SHARED_MEMORY 1" >>confdefs.h
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SHMEM_IMPLEMENTATION="src/backend/port/win32_shmem.c"
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fi
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# Select random number source
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#
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# You can override this logic by setting the appropriate USE_*RANDOM flag to 1
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# in the template or configure command line.
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# If not selected manually, try to select a source automatically.
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if test "$enable_strong_random" = "yes" && test x"$USE_OPENSSL_RANDOM" = x"" && test x"$USE_WIN32_RANDOM" = x"" && test x"$USE_DEV_URANDOM" = x"" ; then
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if test x"$with_openssl" = x"yes" ; then
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USE_OPENSSL_RANDOM=1
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elif test "$PORTNAME" = x"win32" ; then
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USE_WIN32_RANDOM=1
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else
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{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for /dev/urandom" >&5
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$as_echo_n "checking for /dev/urandom... " >&6; }
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if ${ac_cv_file__dev_urandom+:} false; then :
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$as_echo_n "(cached) " >&6
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else
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test "$cross_compiling" = yes &&
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as_fn_error $? "cannot check for file existence when cross compiling" "$LINENO" 5
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if test -r "/dev/urandom"; then
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ac_cv_file__dev_urandom=yes
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else
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ac_cv_file__dev_urandom=no
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fi
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fi
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{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_file__dev_urandom" >&5
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$as_echo "$ac_cv_file__dev_urandom" >&6; }
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if test "x$ac_cv_file__dev_urandom" = xyes; then :
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fi
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if test x"$ac_cv_file__dev_urandom" = x"yes" ; then
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USE_DEV_URANDOM=1
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fi
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fi
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fi
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{ $as_echo "$as_me:${as_lineno-$LINENO}: checking which random number source to use" >&5
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$as_echo_n "checking which random number source to use... " >&6; }
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if test "$enable_strong_random" = yes ; then
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if test x"$USE_OPENSSL_RANDOM" = x"1" ; then
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$as_echo "#define USE_OPENSSL_RANDOM 1" >>confdefs.h
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{ $as_echo "$as_me:${as_lineno-$LINENO}: result: OpenSSL" >&5
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$as_echo "OpenSSL" >&6; }
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elif test x"$USE_WIN32_RANDOM" = x"1" ; then
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$as_echo "#define USE_WIN32_RANDOM 1" >>confdefs.h
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{ $as_echo "$as_me:${as_lineno-$LINENO}: result: Windows native" >&5
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$as_echo "Windows native" >&6; }
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elif test x"$USE_DEV_URANDOM" = x"1" ; then
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$as_echo "#define USE_DEV_URANDOM 1" >>confdefs.h
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{ $as_echo "$as_me:${as_lineno-$LINENO}: result: /dev/urandom" >&5
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$as_echo "/dev/urandom" >&6; }
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else
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as_fn_error $? "
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no source of strong random numbers was found
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PostgreSQL can use OpenSSL or /dev/urandom as a source of random numbers,
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for authentication protocols. You can use --disable-strong-random to use of a built-in
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pseudo random number generator, but that may be insecure." "$LINENO" 5
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fi
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$as_echo "#define HAVE_STRONG_RANDOM 1" >>confdefs.h
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else
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{ $as_echo "$as_me:${as_lineno-$LINENO}: result: weak builtin PRNG" >&5
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$as_echo "weak builtin PRNG" >&6; }
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{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING:
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*** Not using a strong random number source may be insecure." >&5
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$as_echo "$as_me: WARNING:
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*** Not using a strong random number source may be insecure." >&2;}
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fi
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# If not set in template file, set bytes to use libc memset()
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if test x"$MEMSET_LOOP_LIMIT" = x"" ; then
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MEMSET_LOOP_LIMIT=1024
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