Allow to use system CA pool for certificate verification

This adds a new option to libpq's sslrootcert, "system", which will load
the system trusted CA roots for certificate verification. This is a more
convenient way to achieve this than pointing to the system CA roots
manually since the location can differ by installation and be locally
adjusted by env vars in OpenSSL.

When sslrootcert is set to system, sslmode is forced to be verify-full
as weaker modes aren't providing much security for public CAs.

Changing the location of the system roots by setting environment vars is
not supported by LibreSSL so the tests will use a heuristic to determine
if the system being tested is LibreSSL or OpenSSL.

The workaround in .cirrus.yml is required to handle a strange interaction
between homebrew and the openssl@3 formula; hopefully this can be removed
in the near future.

The original patch was written by Thomas Habets, which was later revived
by Jacob Champion.

Author: Jacob Champion <[email protected]>
Author: Thomas Habets <[email protected]>
Reviewed-by: Jelte Fennema <[email protected]>
Reviewed-by: Andrew Dunstan <[email protected]>
Reviewed-by: Magnus Hagander <[email protected]>
Discussion: https://www.postgresql.org/message-id/flat/CA%2BkHd%2BcJwCUxVb-Gj_0ptr3_KZPwi3%2B67vK6HnLFBK9MzuYrLA%40mail.gmail.com

1 files changed, 28 insertions, 2 deletions

diff --git a/src/interfaces/libpq/t/001_uri.pl b/src/interfaces/libpq/t/001_uri.pl
index 2ab537f97f1..cd659bc1b0f 100644
--- a/src/interfaces/libpq/t/001_uri.pl
+++ b/src/interfaces/libpq/t/001_uri.pl
@@ -8,7 +8,9 @@ use IPC::Run;
 
 
 # List of URIs tests. For each test the first element is the input string, the
-# second the expected stdout and the third the expected stderr.
+# second the expected stdout and the third the expected stderr. Optionally,
+# additional arguments may specify key/value pairs which will override
+# environment variables for the duration of the test.
 my @tests = (
 	[
 		q{postgresql://uri-user:secret@host:12345/db},
@@ -209,20 +211,44 @@ my @tests = (
 		q{postgres://%2Fvar%2Flib%2Fpostgresql/dbname},
 		q{dbname='dbname' host='/var/lib/postgresql' (local)},
 		q{},
+	],
+	# Usually the default sslmode is 'prefer' (for libraries with SSL) or
+	# 'disable' (for those without). This default changes to 'verify-full' if
+	# the system CA store is in use.
+	[
+		q{postgresql://host?sslmode=disable},
+		q{host='host' sslmode='disable' (inet)},
+		q{},
+		PGSSLROOTCERT => "system",
+	],
+	[
+		q{postgresql://host?sslmode=prefer},
+		q{host='host' sslmode='prefer' (inet)},
+		q{},
+		PGSSLROOTCERT => "system",
+	],
+	[
+		q{postgresql://host?sslmode=verify-full},
+		q{host='host' (inet)},
+		q{},
+		PGSSLROOTCERT => "system",
 	]);
 
 # test to run for each of the above test definitions
 sub test_uri
 {
 	local $Test::Builder::Level = $Test::Builder::Level + 1;
+	local %ENV = %ENV;
 
 	my $uri;
 	my %expect;
+	my %envvars;
 	my %result;
 
-	($uri, $expect{stdout}, $expect{stderr}) = @$_;
+	($uri, $expect{stdout}, $expect{stderr}, %envvars) = @$_;
 
 	$expect{'exit'} = $expect{stderr} eq '';
+	%ENV = (%ENV, %envvars);
 
 	my $cmd = [ 'libpq_uri_regress', $uri ];
 	$result{exit} = IPC::Run::run $cmd, '>', \$result{stdout}, '2>',