From 7f56d43663dd06e23aeb9a5265d3e16e8616e9d8 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Tue, 23 Apr 2019 15:43:32 +0900 Subject: [PATCH] Fix detection of passwords hashed with MD5 or SCRAM-SHA-256 This commit fixes a couple of issues related to the way password verifiers hashed with MD5 or SCRAM-SHA-256 are detected, leading to being able to store in catalogs passwords which do not follow the supported hash formats: - A MD5-hashed entry was checked based on if its header uses "md5" and if the string length matches what is expected. Unfortunately the code never checked if the hash only used hexadecimal characters, as reported by Tom Lane. - A SCRAM-hashed entry was checked based on only its header, which should be "SCRAM-SHA-256$", but it never checked for any fields afterwards, as reported by Jonathan Katz. Backpatch down to v10, which is where SCRAM has been introduced, and where password verifiers in plain format have been removed. Author: Jonathan Katz Reviewed-by: Tom Lane, Michael Paquier Discussion: https://postgr.es/m/016deb6b-1f0a-8e9f-1833-a8675b170aa9@postgresql.org Backpatch-through: 10 --- src/backend/libpq/auth-scram.c | 4 +--- src/backend/libpq/crypt.c | 13 +++++++++++-- src/include/common/md5.h | 1 + src/include/libpq/scram.h | 2 ++ src/test/regress/expected/password.out | 17 ++++++++++++++++- src/test/regress/sql/password.sql | 13 +++++++++++++ 6 files changed, 44 insertions(+), 6 deletions(-) diff --git a/src/backend/libpq/auth-scram.c b/src/backend/libpq/auth-scram.c index e997c94600..c110cb0720 100644 --- a/src/backend/libpq/auth-scram.c +++ b/src/backend/libpq/auth-scram.c @@ -162,8 +162,6 @@ 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); @@ -547,7 +545,7 @@ 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 2c5ce4a47e..0f19ed60f8 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 +91,17 @@ get_role_password(const char *role, char **logdetail) PasswordType get_password_type(const char *shadow_pass) { - if (strncmp(shadow_pass, "md5", 3) == 0 && strlen(shadow_pass) == MD5_PASSWD_LEN) + 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 && + strspn(shadow_pass + 3, MD5_PASSWD_CHARSET) == MD5_PASSWD_LEN - 3) return PASSWORD_TYPE_MD5; - if (strncmp(shadow_pass, "SCRAM-SHA-256$", strlen("SCRAM-SHA-256$")) == 0) + if (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/common/md5.h b/src/include/common/md5.h index 905d3aa219..f418135a9a 100644 --- a/src/include/common/md5.h +++ b/src/include/common/md5.h @@ -16,6 +16,7 @@ #ifndef PG_MD5_H #define PG_MD5_H +#define MD5_PASSWD_CHARSET "0123456789abcdef" #define MD5_PASSWD_LEN 35 extern bool pg_md5_hash(const void *buff, size_t len, char *hexsum); diff --git a/src/include/libpq/scram.h b/src/include/libpq/scram.h index f7865ca5fc..7e5dd14127 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, 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..971e290a32 100644 --- a/src/test/regress/expected/password.out +++ b/src/test/regress/expected/password.out @@ -62,6 +62,15 @@ SET password_encryption = 'scram-sha-256'; ALTER ROLE regress_passwd4 PASSWORD 'foo'; -- already encrypted with MD5, use as it is CREATE ROLE regress_passwd5 PASSWORD 'md5e73a4b11df52a6068f8b39f90be36023'; +-- This looks like a valid SCRAM-SHA-256 verifier, but it is not +-- so it should be hashed with SCRAM-SHA-256. +CREATE ROLE regress_passwd6 PASSWORD 'SCRAM-SHA-256$1234'; +-- These may look like valid MD5 verifiers, but they are not, so they +-- should be hashed with SCRAM-SHA-256. +-- trailing garbage at the end +CREATE ROLE regress_passwd7 PASSWORD 'md5012345678901234567890123456789zz'; +-- invalid length +CREATE ROLE regress_passwd8 PASSWORD 'md501234567890123456789012345678901zz'; SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/=]+)\$([a-zA-Z0-9+=/]+):([a-zA-Z0-9+/=]+)', '\1$\2:$:') as rolpassword_masked FROM pg_authid WHERE rolname LIKE 'regress_passwd%' @@ -73,7 +82,10 @@ SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+ regress_passwd3 | SCRAM-SHA-256$4096:$: regress_passwd4 | SCRAM-SHA-256$4096:$: regress_passwd5 | md5e73a4b11df52a6068f8b39f90be36023 -(5 rows) + regress_passwd6 | SCRAM-SHA-256$4096:$: + regress_passwd7 | SCRAM-SHA-256$4096:$: + regress_passwd8 | SCRAM-SHA-256$4096:$: +(8 rows) -- An empty password is not allowed, in any form CREATE ROLE regress_passwd_empty PASSWORD ''; @@ -93,6 +105,9 @@ DROP ROLE regress_passwd2; DROP ROLE regress_passwd3; DROP ROLE regress_passwd4; DROP ROLE regress_passwd5; +DROP ROLE regress_passwd6; +DROP ROLE regress_passwd7; +DROP ROLE regress_passwd8; 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..89b6d4b278 100644 --- a/src/test/regress/sql/password.sql +++ b/src/test/regress/sql/password.sql @@ -54,6 +54,16 @@ ALTER ROLE regress_passwd4 PASSWORD 'foo'; -- already encrypted with MD5, use as it is CREATE ROLE regress_passwd5 PASSWORD 'md5e73a4b11df52a6068f8b39f90be36023'; +-- This looks like a valid SCRAM-SHA-256 verifier, but it is not +-- so it should be hashed with SCRAM-SHA-256. +CREATE ROLE regress_passwd6 PASSWORD 'SCRAM-SHA-256$1234'; +-- These may look like valid MD5 verifiers, but they are not, so they +-- should be hashed with SCRAM-SHA-256. +-- trailing garbage at the end +CREATE ROLE regress_passwd7 PASSWORD 'md5012345678901234567890123456789zz'; +-- invalid length +CREATE ROLE regress_passwd8 PASSWORD 'md501234567890123456789012345678901zz'; + SELECT rolname, regexp_replace(rolpassword, '(SCRAM-SHA-256)\$(\d+):([a-zA-Z0-9+/=]+)\$([a-zA-Z0-9+=/]+):([a-zA-Z0-9+/=]+)', '\1$\2:$:') as rolpassword_masked FROM pg_authid WHERE rolname LIKE 'regress_passwd%' @@ -70,6 +80,9 @@ DROP ROLE regress_passwd2; DROP ROLE regress_passwd3; DROP ROLE regress_passwd4; DROP ROLE regress_passwd5; +DROP ROLE regress_passwd6; +DROP ROLE regress_passwd7; +DROP ROLE regress_passwd8; DROP ROLE regress_passwd_empty; -- all entries should have been removed