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b577743000
Replace the hardcoded value with a GUC such that the iteration count can be raised in order to increase protection against brute-force attacks. The hardcoded value for SCRAM iteration count was defined to be 4096, which is taken from RFC 7677, so set the default for the GUC to 4096 to match. In RFC 7677 the recommendation is at least 15000 iterations but 4096 is listed as a SHOULD requirement given that it's estimated to yield a 0.5s processing time on a mobile handset of the time of RFC writing (late 2015). Raising the iteration count of SCRAM will make stored passwords more resilient to brute-force attacks at a higher computational cost during connection establishment. Lowering the count will reduce computational overhead during connections at the tradeoff of reducing strength against brute-force attacks. There are however platforms where even a modest iteration count yields a too high computational overhead, with weaker password encryption schemes chosen as a result. In these situations, SCRAM with a very low iteration count still gives benefits over weaker schemes like md5, so we allow the iteration count to be set to one at the low end. The new GUC is intentionally generically named such that it can be made to support future SCRAM standards should they emerge. At that point the value can be made into key:value pairs with an undefined key as a default which will be backwards compatible with this. Reviewed-by: Michael Paquier <michael@paquier.xyz> Reviewed-by: Jonathan S. Katz <jkatz@postgresql.org> Discussion: https://postgr.es/m/F72E7BC7-189F-4B17-BF47-9735EB72C364@yesql.se
114 lines
5.1 KiB
SQL
114 lines
5.1 KiB
SQL
--
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-- Tests for password types
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--
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-- Tests for GUC password_encryption
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SET password_encryption = 'novalue'; -- error
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SET password_encryption = true; -- error
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SET password_encryption = 'md5'; -- ok
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SET password_encryption = 'scram-sha-256'; -- ok
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-- consistency of password entries
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SET password_encryption = 'md5';
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CREATE ROLE regress_passwd1 PASSWORD 'role_pwd1';
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CREATE ROLE regress_passwd2 PASSWORD 'role_pwd2';
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SET password_encryption = 'scram-sha-256';
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CREATE ROLE regress_passwd3 PASSWORD 'role_pwd3';
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CREATE ROLE regress_passwd4 PASSWORD NULL;
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-- check list of created entries
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--
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-- The scram secret will look something like:
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-- SCRAM-SHA-256$4096:E4HxLGtnRzsYwg==$6YtlR4t69SguDiwFvbVgVZtuz6gpJQQqUMZ7IQJK5yI=:ps75jrHeYU4lXCcXI4O8oIdJ3eO8o2jirjruw9phBTo=
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--
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-- Since the salt is random, the exact value stored will be different on every test
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-- run. Use a regular expression to mask the changing parts.
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SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/=]+)\$([a-zA-Z0-9+=/]+):([a-zA-Z0-9+/=]+)', '\1$\2:<salt>$<storedkey>:<serverkey>') as rolpassword_masked
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FROM pg_authid
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WHERE rolname LIKE 'regress_passwd%'
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ORDER BY rolname, rolpassword;
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-- Rename a role
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ALTER ROLE regress_passwd2 RENAME TO regress_passwd2_new;
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-- md5 entry should have been removed
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SELECT rolname, rolpassword
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FROM pg_authid
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WHERE rolname LIKE 'regress_passwd2_new'
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ORDER BY rolname, rolpassword;
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ALTER ROLE regress_passwd2_new RENAME TO regress_passwd2;
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-- Change passwords with ALTER USER. With plaintext or already-encrypted
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-- passwords.
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SET password_encryption = 'md5';
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-- encrypt with MD5
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ALTER ROLE regress_passwd2 PASSWORD 'foo';
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-- already encrypted, use as they are
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ALTER ROLE regress_passwd1 PASSWORD 'md5cd3578025fe2c3d7ed1b9a9b26238b70';
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ALTER ROLE regress_passwd3 PASSWORD 'SCRAM-SHA-256$4096:VLK4RMaQLCvNtQ==$6YtlR4t69SguDiwFvbVgVZtuz6gpJQQqUMZ7IQJK5yI=:ps75jrHeYU4lXCcXI4O8oIdJ3eO8o2jirjruw9phBTo=';
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SET password_encryption = 'scram-sha-256';
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-- create SCRAM secret
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ALTER ROLE regress_passwd4 PASSWORD 'foo';
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-- already encrypted with MD5, use as it is
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CREATE ROLE regress_passwd5 PASSWORD 'md5e73a4b11df52a6068f8b39f90be36023';
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-- This looks like a valid SCRAM-SHA-256 secret, but it is not
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-- so it should be hashed with SCRAM-SHA-256.
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CREATE ROLE regress_passwd6 PASSWORD 'SCRAM-SHA-256$1234';
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-- These may look like valid MD5 secrets, but they are not, so they
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-- should be hashed with SCRAM-SHA-256.
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-- trailing garbage at the end
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CREATE ROLE regress_passwd7 PASSWORD 'md5012345678901234567890123456789zz';
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-- invalid length
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CREATE ROLE regress_passwd8 PASSWORD 'md501234567890123456789012345678901zz';
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-- Changing the SCRAM iteration count
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SET scram_iterations = 1024;
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CREATE ROLE regress_passwd9 PASSWORD 'alterediterationcount';
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SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/=]+)\$([a-zA-Z0-9+=/]+):([a-zA-Z0-9+/=]+)', '\1$\2:<salt>$<storedkey>:<serverkey>') as rolpassword_masked
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FROM pg_authid
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WHERE rolname LIKE 'regress_passwd%'
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ORDER BY rolname, rolpassword;
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-- An empty password is not allowed, in any form
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CREATE ROLE regress_passwd_empty PASSWORD '';
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ALTER ROLE regress_passwd_empty PASSWORD 'md585939a5ce845f1a1b620742e3c659e0a';
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ALTER ROLE regress_passwd_empty PASSWORD 'SCRAM-SHA-256$4096:hpFyHTUsSWcR7O9P$LgZFIt6Oqdo27ZFKbZ2nV+vtnYM995pDh9ca6WSi120=:qVV5NeluNfUPkwm7Vqat25RjSPLkGeoZBQs6wVv+um4=';
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SELECT rolpassword FROM pg_authid WHERE rolname='regress_passwd_empty';
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-- Test with invalid stored and server keys.
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--
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-- The first is valid, to act as a control. The others have too long
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-- stored/server keys. They will be re-hashed.
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CREATE ROLE regress_passwd_sha_len0 PASSWORD 'SCRAM-SHA-256$4096:A6xHKoH/494E941doaPOYg==$Ky+A30sewHIH3VHQLRN9vYsuzlgNyGNKCh37dy96Rqw=:COPdlNiIkrsacU5QoxydEuOH6e/KfiipeETb/bPw8ZI=';
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CREATE ROLE regress_passwd_sha_len1 PASSWORD 'SCRAM-SHA-256$4096:A6xHKoH/494E941doaPOYg==$Ky+A30sewHIH3VHQLRN9vYsuzlgNyGNKCh37dy96RqwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=:COPdlNiIkrsacU5QoxydEuOH6e/KfiipeETb/bPw8ZI=';
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CREATE ROLE regress_passwd_sha_len2 PASSWORD 'SCRAM-SHA-256$4096:A6xHKoH/494E941doaPOYg==$Ky+A30sewHIH3VHQLRN9vYsuzlgNyGNKCh37dy96Rqw=:COPdlNiIkrsacU5QoxydEuOH6e/KfiipeETb/bPw8ZIAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=';
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-- Check that the invalid secrets were re-hashed. A re-hashed secret
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-- should not contain the original salt.
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SELECT rolname, rolpassword not like '%A6xHKoH/494E941doaPOYg==%' as is_rolpassword_rehashed
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FROM pg_authid
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WHERE rolname LIKE 'regress_passwd_sha_len%'
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ORDER BY rolname;
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DROP ROLE regress_passwd1;
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DROP ROLE regress_passwd2;
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DROP ROLE regress_passwd3;
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DROP ROLE regress_passwd4;
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DROP ROLE regress_passwd5;
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DROP ROLE regress_passwd6;
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DROP ROLE regress_passwd7;
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DROP ROLE regress_passwd8;
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DROP ROLE regress_passwd9;
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DROP ROLE regress_passwd_empty;
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DROP ROLE regress_passwd_sha_len0;
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DROP ROLE regress_passwd_sha_len1;
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DROP ROLE regress_passwd_sha_len2;
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-- all entries should have been removed
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SELECT rolname, rolpassword
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FROM pg_authid
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WHERE rolname LIKE 'regress_passwd%'
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ORDER BY rolname, rolpassword;
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