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Based on an analysis of the OpenSSL code with Jacob, moving to EVP for the cryptohash computations makes necessary the setup of the libcrypto callbacks that were getting set only for SSL connections, but not for connections without SSL. Not setting the callbacks makes the use of threads potentially unsafe for connections calling cryptohashes during authentication, like MD5 or SCRAM, if a failure happens during a cryptohash computation. The logic setting the libssl and libcrypto states is then split into two parts, both using the same locking, with libcrypto being set up for SSL and non-SSL connections, while SSL connections set any libssl state afterwards as needed. Prior to this commit, only SSL connections would have set libcrypto callbacks that are necessary to ensure a proper thread locking when using multiple concurrent threads in libpq (ENABLE_THREAD_SAFETY). Note that this is only required for OpenSSL 1.0.2 and 1.0.1 (oldest version supported on HEAD), as 1.1.0 has its own internal locking and it has dropped support for CRYPTO_set_locking_callback(). Tests with up to 300 threads with OpenSSL 1.0.1 and 1.0.2, mixing SSL and non-SSL connection threads did not show any performance impact after some micro-benchmarking. pgbench can be used here with -C and a mostly-empty script (with one \set meta-command for example) to stress authentication requests, and we have mixed that with some custom programs for testing. Reported-by: Jacob Champion Author: Michael Paquier Reviewed-by: Jacob Champion Discussion: https://postgr.es/m/fd3ba610085f1ff54623478cf2f7adf5af193cbb.camel@vmware.com
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/.