Date: Tue, 23 Apr 2019 15:57:01 +0900
From: Michael Paquier <michael@paquier.xyz>
To: "Jonathan S. Katz" <jkatz@postgresql.org>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-bugs@lists.postgresql.org,
	Stephen Frost <sfrost@snowman.net>
Subject: Re: Possible to store invalid SCRAM-SHA-256 Passwords
Message-ID: <20190423065701.GL2712@paquier.xyz>
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On Tue, Apr 23, 2019 at 11:10:18AM +0900, Michael Paquier wrote:
> That's a hard morning...  Yes you are right and I can see the failure.
> By the way, grouping everything in one patch looks more adapted to me
> as this tightens all the checks for the different verifier types.

The afternoon has been better.  I have double-checked your patch and
committed it down to v10.  Now, there are two things which may need
extra handling:
- Do we add a note in the release notes about that with a SQL query
checking the state of pg_authid?
- In ~9.6 we include in md5.h a macro which does not care about hex
characters in the MD5 hash.  I think that we should fix that as well,
or perhaps that's not worth caring per the lack of complaints?
Attached is what would be needed.
--
Michael

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diff --git a/src/include/libpq/md5.h b/src/include/libpq/md5.h
index f3eec8b4f4..fac2636c07 100644
--- a/src/include/libpq/md5.h
+++ b/src/include/libpq/md5.h
@@ -16,10 +16,12 @@
 #ifndef PG_MD5_H
 #define PG_MD5_H
=20
+#define MD5_PASSWD_CHARSET "0123456789abcdef"
 #define MD5_PASSWD_LEN	35
=20
 #define isMD5(passwd)	(strncmp(passwd, "md5", 3) =3D=3D 0 && \
-						 strlen(passwd) =3D=3D MD5_PASSWD_LEN)
+						 strlen(passwd) =3D=3D MD5_PASSWD_LEN && \
+						 strspn(passwd + 3, MD5_PASSWD_CHARSET) =3D=3D MD5_PASSWD_LEN - 3)
=20
=20
 extern bool pg_md5_hash(const void *buff, size_t len, char *hexsum);

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