0001-Modified-SCRAM-SHA-256-validation-check-for-get_pass_v2.patch

From 26e52e72010a4c25a69ff32f3a960298b3a99250 Mon Sep 17 00:00:00 2001
From: "Jonathan S. Katz" <jonathan.katz@excoventures.com>
Date: Sat, 20 Apr 2019 16:02:32 -0400
Subject: [PATCH] Modified SCRAM-SHA-256 validation check for get_password_type

The get_password_type function previously just checked to see if a password
started with "SCRAM-SHA-256$" to determine whether or not it was a
SCRAM-SHA-256 hashed password. However, this would cause passwords created
in this was to be unusuable.

This changes get_password_type methodology to actually perform SCRAM-SHA-256
verification on the password to see if it is a valid hash. If not, it will
proceed to the next password type check.
---
 src/backend/libpq/auth-scram.c         |  4 +---
 src/backend/libpq/crypt.c              |  9 ++++++++-
 src/include/libpq/scram.h              |  2 ++
 src/test/regress/expected/password.out | 11 +++++++++++
 src/test/regress/sql/password.sql      |  7 +++++++
 5 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/src/backend/libpq/auth-scram.c b/src/backend/libpq/auth-scram.c
index 3cbe902ace..4c7b149570 100644
--- a/src/backend/libpq/auth-scram.c
+++ b/src/backend/libpq/auth-scram.c
@@ -161,8 +161,6 @@ static char *build_server_first_message(scram_state *state);
 static char *build_server_final_message(scram_state *state);
 static bool verify_client_proof(scram_state *state);
 static bool verify_final_nonce(scram_state *state);
-static bool parse_scram_verifier(const char *verifier, int *iterations,
-					 char **salt, uint8 *stored_key, uint8 *server_key);
 static void mock_scram_verifier(const char *username, int *iterations,
 					char **salt, uint8 *stored_key, uint8 *server_key);
 static bool is_scram_printable(char *p);
@@ -546,7 +544,7 @@ scram_verify_plain_password(const char *username, const char *password,
  *
  * Returns true if the SCRAM verifier has been parsed, and false otherwise.
  */
-static bool
+bool
 parse_scram_verifier(const char *verifier, int *iterations, char **salt,
 					 uint8 *stored_key, uint8 *server_key)
 {
diff --git a/src/backend/libpq/crypt.c b/src/backend/libpq/crypt.c
index c34e4a3d85..db19f51c80 100644
--- a/src/backend/libpq/crypt.c
+++ b/src/backend/libpq/crypt.c
@@ -20,6 +20,7 @@
 
 #include "catalog/pg_authid.h"
 #include "common/md5.h"
+#include "common/scram-common.h"
 #include "libpq/crypt.h"
 #include "libpq/scram.h"
 #include "miscadmin.h"
@@ -90,9 +91,15 @@ get_role_password(const char *role, char **logdetail)
 PasswordType
 get_password_type(const char *shadow_pass)
 {
+	char	   *encoded_salt;
+	int			iterations;
+	uint8		stored_key[SCRAM_KEY_LEN];
+	uint8		server_key[SCRAM_KEY_LEN];
+
 	if (strncmp(shadow_pass, "md5", 3) == 0 && strlen(shadow_pass) == MD5_PASSWD_LEN)
 		return PASSWORD_TYPE_MD5;
-	if (strncmp(shadow_pass, "SCRAM-SHA-256$", strlen("SCRAM-SHA-256$")) == 0)
+	if (strncmp(shadow_pass, "SCRAM-SHA-256$", strlen("SCRAM-SHA-256$")) == 0 &&
+				parse_scram_verifier(shadow_pass, &iterations, &encoded_salt, stored_key, server_key))
 		return PASSWORD_TYPE_SCRAM_SHA_256;
 	return PASSWORD_TYPE_PLAINTEXT;
 }
diff --git a/src/include/libpq/scram.h b/src/include/libpq/scram.h
index d7f4c094c9..bc297e2a33 100644
--- a/src/include/libpq/scram.h
+++ b/src/include/libpq/scram.h
@@ -29,6 +29,8 @@ extern int pg_be_scram_exchange(void *opaq, const char *input, int inputlen,
 
 /* Routines to handle and check SCRAM-SHA-256 verifier */
 extern char *pg_be_scram_build_verifier(const char *password);
+extern bool parse_scram_verifier(const char *verifier, int *iterations, char **salt,
+					 uint8 *stored_key, uint8 *server_key);
 extern bool scram_verify_plain_password(const char *username,
 							const char *password, const char *verifier);
 
diff --git a/src/test/regress/expected/password.out b/src/test/regress/expected/password.out
index 393d836ead..d40dcf9a43 100644
--- a/src/test/regress/expected/password.out
+++ b/src/test/regress/expected/password.out
@@ -75,6 +75,16 @@ SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+
  regress_passwd5 | md5e73a4b11df52a6068f8b39f90be36023
 (5 rows)
 
+-- An invalid SCRAM-SHA-256 that is encrypted is streated as a SCRAM-SHA-256 password
+CREATE ROLE regress_passwd6 PASSWORD 'SCRAM-SHA-256$1234';
+SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/=]+)\$([a-zA-Z0-9+=/]+):([a-zA-Z0-9+/=]+)', '\1$\2:<salt>$<storedkey>:<serverkey>') as rolpassword_masked
+    FROM pg_authid
+    WHERE rolname='regress_passwd6';
+     rolname     |                rolpassword_masked                 
+-----------------+---------------------------------------------------
+ regress_passwd6 | SCRAM-SHA-256$4096:<salt>$<storedkey>:<serverkey>
+(1 row)
+
 -- An empty password is not allowed, in any form
 CREATE ROLE regress_passwd_empty PASSWORD '';
 NOTICE:  empty string is not a valid password, clearing password
@@ -93,6 +103,7 @@ DROP ROLE regress_passwd2;
 DROP ROLE regress_passwd3;
 DROP ROLE regress_passwd4;
 DROP ROLE regress_passwd5;
+DROP ROLE regress_passwd6;
 DROP ROLE regress_passwd_empty;
 -- all entries should have been removed
 SELECT rolname, rolpassword
diff --git a/src/test/regress/sql/password.sql b/src/test/regress/sql/password.sql
index 8f8252d127..b5a0a89182 100644
--- a/src/test/regress/sql/password.sql
+++ b/src/test/regress/sql/password.sql
@@ -59,6 +59,12 @@ SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+
     WHERE rolname LIKE 'regress_passwd%'
     ORDER BY rolname, rolpassword;
 
+-- An invalid SCRAM-SHA-256 that is encrypted is streated as a SCRAM-SHA-256 password
+CREATE ROLE regress_passwd6 PASSWORD 'SCRAM-SHA-256$1234';
+SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/=]+)\$([a-zA-Z0-9+=/]+):([a-zA-Z0-9+/=]+)', '\1$\2:<salt>$<storedkey>:<serverkey>') as rolpassword_masked
+    FROM pg_authid
+    WHERE rolname='regress_passwd6';
+
 -- An empty password is not allowed, in any form
 CREATE ROLE regress_passwd_empty PASSWORD '';
 ALTER ROLE regress_passwd_empty PASSWORD 'md585939a5ce845f1a1b620742e3c659e0a';
@@ -70,6 +76,7 @@ DROP ROLE regress_passwd2;
 DROP ROLE regress_passwd3;
 DROP ROLE regress_passwd4;
 DROP ROLE regress_passwd5;
+DROP ROLE regress_passwd6;
 DROP ROLE regress_passwd_empty;
 
 -- all entries should have been removed
-- 
2.14.3 (Apple Git-98)