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Tom Lane 4203842a1c Use pg_strong_random() to select each server process's random seed. 
Previously we just set the seed based on process ID and start timestamp.
Both those values are directly available within the session, and can
be found out or guessed by other users too, making the session's series
of random(3) values fairly predictable.  Up to now, our backend-internal
uses of random(3) haven't seemed security-critical, but commit 88bdbd3f7
added one that potentially is: when using log_statement_sample_rate, a
user might be able to predict which of his SQL statements will get logged.

To improve this situation, upgrade the per-process seed initialization
method to use pg_strong_random() if available, greatly reducing the
predictability of the initial seed value.  This adds a few tens of
microseconds to process start time, but since backend startup time is
at least a couple of milliseconds, that seems an acceptable price.

This means that pg_strong_random() needs to be able to run without
reliance on any backend infrastructure, since it will be invoked
before any of that is up.  It was safe for that already, but adjust
comments and #include commands to make it clearer.

Discussion: https://postgr.es/m/3859.1545849900@sss.pgh.pa.us
2018-12-29 17:56:06 -05:00
config Update config/ax_pthread.m4 to latest upstream version. 2018-11-19 15:05:33 -05:00
contrib Remove obsolete IndexIs* macros 2018-12-27 10:07:46 +01:00
doc Use a separate random seed for SQL random()/setseed() functions. 2018-12-29 17:33:27 -05:00
src Use pg_strong_random() to select each server process's random seed. 2018-12-29 17:56:06 -05:00
.dir-locals.el Update documentation editor setup instructions 2018-07-13 21:23:41 +02:00
.gitattributes Remove contrib/tsearch2. 2017-02-13 11:06:11 -05:00
.gitignore Support for optimizing and emitting code in LLVM JIT provider. 2018-03-22 11:05:22 -07:00
aclocal.m4 Fix configure's AC_CHECK_DECLS tests to work correctly with clang. 2018-11-19 12:01:47 -05:00
configure Drop support for getting signal descriptions from sys_siglist[]. 2018-12-17 13:50:16 -05:00
configure.in Drop support for getting signal descriptions from sys_siglist[]. 2018-12-17 13:50:16 -05:00
COPYRIGHT Update copyright for 2018 2018-01-02 23:30:12 -05:00
GNUmakefile.in Remove unwanted "garbage cleanup" logic in Makefiles. 2018-08-08 14:32:29 -04:00
HISTORY Change documentation references to PG website to use https: not http: 2017-05-20 21:50:47 -04:00
Makefile Fix non-GNU makefiles for AIX make. 2017-11-30 00:57:22 -08:00
README Change documentation references to PG website to use https: not http: 2017-05-20 21:50:47 -04:00
README.git Change documentation references to PG website to use https: not http: 2017-05-20 21:50:47 -04:00

README 

PostgreSQL Database Management System
=====================================

This directory contains the source code distribution of the PostgreSQL
database management system.

PostgreSQL is an advanced object-relational database management system
that supports an extended subset of the SQL standard, including
transactions, foreign keys, subqueries, triggers, user-defined types
and functions.  This distribution also contains C language bindings.

PostgreSQL has many language interfaces, many of which are listed here:

	https://www.postgresql.org/download

See the file INSTALL for instructions on how to build and install
PostgreSQL.  That file also lists supported operating systems and
hardware platforms and contains information regarding any other
software packages that are required to build or run the PostgreSQL
system.  Copyright and license information can be found in the
file COPYRIGHT.  A comprehensive documentation set is included in this
distribution; it can be read as described in the installation
instructions.

The latest version of this software may be obtained at
https://www.postgresql.org/download/.  For more information look at our
web site located at https://www.postgresql.org/.