Waiting for PostgreSQL 16 – Add support for regexps on database and user entries in pg_hba.conf

On 24th of October 2022, Michael Paquier committed patch:

Add support for regexps on database and user entries in pg_hba.conf
As of this commit, any database or user entry beginning with a slash (/)
is considered as a regular expression.  This is particularly useful for
users, as now there is no clean way to match pattern on multiple HBA
lines.  For example, a user name mapping with a regular expression needs
first to match with a HBA line, and we would skip the follow-up HBA
entries if the ident regexp does *not* match with what has matched in
the HBA line.
pg_hba.conf is able to handle multiple databases and roles with a
comma-separated list of these, hence individual regular expressions that
include commas need to be double-quoted.
At authentication time, user and database names are now checked in the
following order:
- Arbitrary keywords (like "all", the ones beginning by '+' for
membership check), that we know will never have a regexp.  A fancy case
is for physical WAL senders, we *have* to only match "replication" for
the database.
- Regular expression matching.
- Exact match.
The previous logic did the same, but without the regexp step.
We have discussed as well the possibility to support regexp pattern
matching for host names, but these happen to lead to tricky issues based
on what I understand, particularly with host entries that have CIDRs.
This commit relies heavily on the refactoring done in a903971 and
fc579e1, so as the amount of code required to compile and execute
regular expressions is now minimal.  When parsing pg_hba.conf, all the
computed regexps needs to explicitely free()'d, same as pg_ident.conf.
Documentation and TAP tests are added to cover this feature, including
cases where the regexps use commas (for clarity in the docs, coverage
for the parsing logic in the tests).
Note that this introduces a breakage with older versions, where a
database or user name beginning with a slash are treated as something to
check for an equal match.  Per discussion, we have discarded this as
being much of an issue in practice as it would require a cluster to
have database and/or role names that begin with a slash, as well as HBA
entries using these.  Hence, the consistency gained with regexps in
pg_ident.conf is more appealing in the long term.
**This compatibility change should be mentioned in the release notes.**
Author: Bertrand Drouvot
Reviewed-by: Jacob Champion, Tom Lane, Michael Paquier
Discussion: https://postgr.es/m/fff0d7c1-8ad4-76a1-9db3-0ab6ec338bf7@amazon.com

Continue reading Waiting for PostgreSQL 16 – Add support for regexps on database and user entries in pg_hba.conf

Waiting for PostgreSQL 10 – Support SCRAM-SHA-256 authentication (RFC 5802 and 7677).

On 7th of March 2017, Heikki Linnakangas committed patch:

Support SCRAM-SHA-256 authentication (RFC 5802 and 7677).
This introduces a new generic SASL authentication method, similar to the
GSS and SSPI methods. The server first tells the client which SASL
authentication mechanism to use, and then the mechanism-specific SASL
messages are exchanged in AuthenticationSASLcontinue and PasswordMessage
messages. Only SCRAM-SHA-256 is supported at the moment, but this allows
adding more SASL mechanisms in the future, without changing the overall
Support for channel binding, aka SCRAM-SHA-256-PLUS is left for later.
The SASLPrep algorithm, for pre-processing the password, is not yet
implemented. That could cause trouble, if you use a password with
non-ASCII characters, and a client library that does implement SASLprep.
That will hopefully be added later.
Authorization identities, as specified in the SCRAM-SHA-256 specification,
are ignored. SET SESSION AUTHORIZATION provides more or less the same
functionality, anyway.
If a user doesn't exist, perform a "mock" authentication, by constructing
an authentic-looking challenge on the fly. The challenge is derived from
a new system-wide random value, "mock authentication nonce", which is
created at initdb, and stored in the control file. We go through these
motions, in order to not give away the information on whether the user
exists, to unauthenticated users.
Bumps PG_CONTROL_VERSION, because of the new field in control file.
Patch by Michael Paquier and Heikki Linnakangas, reviewed at different
stages by Robert Haas, Stephen Frost, David Steele, Aleksander Alekseev,
and many others.
Discussion: https://www.postgresql.org/message-id/CAB7nPqRbR3GmFYdedCAhzukfKrgBLTLtMvENOmPrVWREsZkF8g%40mail.gmail.com
Discussion: https://www.postgresql.org/message-id/CAB7nPqSMXU35g%3DW9X74HVeQp0uvgJxvYOuA4A-A3M%2B0wfEBv-w%40mail.gmail.com
Discussion: https://www.postgresql.org/message-id/.6080106@iki.fi

Continue reading Waiting for PostgreSQL 10 – Support SCRAM-SHA-256 authentication (RFC 5802 and 7677).

Waiting for 8.5 – ‘samehost’ and ‘samenet’ in pg_hba.conf

October, finally. “Only" 1 month of backlog in new features in 8.5, but I'm getting there 🙂

So, on 1st of October Tom Lane committed patch by Stef Walter:

Log Message:
Support "samehost" and "samenet" specifications in pg_hba.conf,
by enumerating the machine's IP interfaces to look for a match.
Stef Walter

For some reason I cannot find it in mailing list archive, but luckily have copy of email (without all headers unfortunately).

Continue reading Waiting for 8.5 – ‘samehost' and ‘samenet' in pg_hba.conf

Recovering from a lost PostgreSQL password.

Let's say you're in situation when you have to connect to PostgreSQL, but you have no idea on what password might be set. But some definitely is, as you get this error message:

=> psql
psql: FATAL:  password authentication failed for user "depesz"

Continue reading Recovering from a lost PostgreSQL password.