From 65fcb8c9565c7f4ba5c204af775c29c76d474a57 Mon Sep 17 00:00:00 2001 From: Matheus Alcantara Date: Tue, 19 Nov 2024 15:37:57 -0300 Subject: [PATCH v1] postgres_fdw: SCRAM authentication pass-through This commit enable SCRAM authentication for postgres_fdw when connecting to a fdw server without having to store a plain-text password on user mapping options. This is done by saving the SCRAM ClientKey and ServeryKey from the client authentication and using those instead of the plain-text password for the server-side SCRAM exchange. --- contrib/postgres_fdw/Makefile | 1 + contrib/postgres_fdw/connection.c | 67 ++++++++++++++++++++++-- contrib/postgres_fdw/meson.build | 5 ++ contrib/postgres_fdw/option.c | 3 ++ contrib/postgres_fdw/t/001_auth_scram.pl | 62 ++++++++++++++++++++++ src/backend/libpq/auth-scram.c | 16 ++++-- src/include/libpq/libpq-be.h | 9 ++++ src/interfaces/libpq/fe-auth-scram.c | 29 ++++++++-- src/interfaces/libpq/fe-auth.c | 2 +- src/interfaces/libpq/fe-connect.c | 31 +++++++++++ src/interfaces/libpq/libpq-int.h | 6 +++ 11 files changed, 217 insertions(+), 14 deletions(-) create mode 100644 contrib/postgres_fdw/t/001_auth_scram.pl diff --git a/contrib/postgres_fdw/Makefile b/contrib/postgres_fdw/Makefile index 88fdce40d6..6c12c8e925 100644 --- a/contrib/postgres_fdw/Makefile +++ b/contrib/postgres_fdw/Makefile @@ -8,6 +8,7 @@ OBJS = \ option.o \ postgres_fdw.o \ shippable.o +TAP_TESTS = 1 PGFILEDESC = "postgres_fdw - foreign data wrapper for PostgreSQL" PG_CPPFLAGS = -I$(libpq_srcdir) diff --git a/contrib/postgres_fdw/connection.c b/contrib/postgres_fdw/connection.c index 2326f391d3..e0e1ebe0d4 100644 --- a/contrib/postgres_fdw/connection.c +++ b/contrib/postgres_fdw/connection.c @@ -19,6 +19,7 @@ #include "access/xact.h" #include "catalog/pg_user_mapping.h" #include "commands/defrem.h" +#include "common/base64.h" #include "funcapi.h" #include "libpq/libpq-be.h" #include "libpq/libpq-be-fe-helpers.h" @@ -168,6 +169,7 @@ static void pgfdw_finish_abort_cleanup(List *pending_entries, static void pgfdw_security_check(const char **keywords, const char **values, UserMapping *user, PGconn *conn); static bool UserMappingPasswordRequired(UserMapping *user); +static bool UseScramPassthrough(ForeignServer *server, UserMapping *user); static bool disconnect_cached_connections(Oid serverid); static void postgres_fdw_get_connections_internal(FunctionCallInfo fcinfo, enum pgfdwVersion api_version); @@ -476,7 +478,7 @@ connect_pg_server(ForeignServer *server, UserMapping *user) * for application_name, fallback_application_name, client_encoding, * end marker. */ - n = list_length(server->options) + list_length(user->options) + 4; + n = list_length(server->options) + list_length(user->options) + 4 + 2; keywords = (const char **) palloc(n * sizeof(char *)); values = (const char **) palloc(n * sizeof(char *)); @@ -545,10 +547,37 @@ connect_pg_server(ForeignServer *server, UserMapping *user) values[n] = GetDatabaseEncodingName(); n++; + if (MyProcPort->has_scram_keys && UseScramPassthrough(server, user)) + { + int len; + + keywords[n] = "scram_client_key"; + len = pg_b64_enc_len(sizeof(MyProcPort->scram_ClientKey)); + /* don't forget the zero-terminator */ + values[n] = palloc0(len+1); + pg_b64_encode((const char *) MyProcPort->scram_ClientKey, + sizeof(MyProcPort->scram_ClientKey), + (char *) values[n], len); + n++; + + keywords[n] = "scram_server_key"; + len = pg_b64_enc_len(sizeof(MyProcPort->scram_ServerKey)); + /* don't forget the zero-terminator */ + values[n] = palloc0(len+1); + pg_b64_encode((const char *) MyProcPort->scram_ServerKey, + sizeof(MyProcPort->scram_ServerKey), + (char *) values[n], len); + n++; + } + keywords[n] = values[n] = NULL; - /* verify the set of connection parameters */ - check_conn_params(keywords, values, user); + /* + * Verify the set of connection parameters only if scram pass-through + * is not being used because the password is not necessary. + */ + if (!(MyProcPort->has_scram_keys && UseScramPassthrough(server, user))) + check_conn_params(keywords, values, user); /* first time, allocate or get the custom wait event */ if (pgfdw_we_connect == 0) @@ -566,8 +595,12 @@ connect_pg_server(ForeignServer *server, UserMapping *user) server->servername), errdetail_internal("%s", pchomp(PQerrorMessage(conn))))); - /* Perform post-connection security checks */ - pgfdw_security_check(keywords, values, user, conn); + /* + * Perform post-connection security checks only if scram pass-through + * is not being used because the password is not necessary. + */ + if (!(MyProcPort->has_scram_keys && UseScramPassthrough(server, user))) + pgfdw_security_check(keywords, values, user, conn); /* Prepare new session for use */ configure_remote_session(conn); @@ -620,6 +653,30 @@ UserMappingPasswordRequired(UserMapping *user) return true; } +static bool +UseScramPassthrough(ForeignServer *server, UserMapping *user) +{ + ListCell *cell; + + foreach(cell, server->options) + { + DefElem *def = (DefElem *) lfirst(cell); + + if (strcmp(def->defname, "use_scram_passthrough") == 0) + return defGetBoolean(def); + } + + foreach(cell, user->options) + { + DefElem *def = (DefElem *) lfirst(cell); + + if (strcmp(def->defname, "use_scram_passthrough") == 0) + return defGetBoolean(def); + } + + return false; +} + /* * For non-superusers, insist that the connstr specify a password or that the * user provided their own GSSAPI delegated credentials. This diff --git a/contrib/postgres_fdw/meson.build b/contrib/postgres_fdw/meson.build index 3014086ba6..27d07188fc 100644 --- a/contrib/postgres_fdw/meson.build +++ b/contrib/postgres_fdw/meson.build @@ -41,4 +41,9 @@ tests += { ], 'regress_args': ['--dlpath', meson.build_root() / 'src/test/regress'], }, + 'tap': { + 'tests': [ + 't/001_auth_scram.pl', + ], + }, } diff --git a/contrib/postgres_fdw/option.c b/contrib/postgres_fdw/option.c index 232d85354b..15abc64381 100644 --- a/contrib/postgres_fdw/option.c +++ b/contrib/postgres_fdw/option.c @@ -279,6 +279,9 @@ InitPgFdwOptions(void) {"analyze_sampling", ForeignServerRelationId, false}, {"analyze_sampling", ForeignTableRelationId, false}, + {"use_scram_passthrough", ForeignServerRelationId, false}, + {"use_scram_passthrough", UserMappingRelationId, false}, + /* * sslcert and sslkey are in fact libpq options, but we repeat them * here to allow them to appear in both foreign server context (when diff --git a/contrib/postgres_fdw/t/001_auth_scram.pl b/contrib/postgres_fdw/t/001_auth_scram.pl new file mode 100644 index 0000000000..388d2179db --- /dev/null +++ b/contrib/postgres_fdw/t/001_auth_scram.pl @@ -0,0 +1,62 @@ +# Copyright (c) 2021-2024, PostgreSQL Global Development Group + +# Test SCRAM authentication pass through the intermediary postgres_fdw to the server + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Utils; +use PostgreSQL::Test::Cluster; +use Test::More; + +my $node = PostgreSQL::Test::Cluster->new('node'); +my $hostaddr = '127.0.0.1'; +my $user = "user01"; +my $db1 = "db1"; +my $db2 = "db2"; +my $fdw_server = "db2_fdw"; +my $host = $node->host; +my $port = $node->port; +my $connstr = $node->connstr($db1) . qq' user=$user'; + +$node->init; +$node->start; + +# Test setup + +$node->safe_psql('postgres', qq'CREATE USER $user WITH password \'pass\' '); +$node->safe_psql('postgres', qq'CREATE DATABASE $db1'); +$node->safe_psql('postgres', qq'CREATE DATABASE $db2'); + +$node->safe_psql($db2, 'CREATE TABLE t AS SELECT g,g+1 FROM generate_series(1,10) g(g)'); +$node->safe_psql($db2, qq'GRANT USAGE ON SCHEMA public to $user'); +$node->safe_psql($db2, qq'GRANT SELECT ON t to $user'); + +$node->safe_psql($db1, 'CREATE EXTENSION IF NOT EXISTS postgres_fdw'); +$node->safe_psql($db1, qq'CREATE SERVER $fdw_server FOREIGN DATA WRAPPER postgres_fdw options ( + host \'$host\', port \'$port\', dbname \'$db2\', use_scram_passthrough \'true\') '); +# password not required +$node->safe_psql($db1, qq'CREATE USER MAPPING FOR $user SERVER $fdw_server OPTIONS (user \'$user\');'); +$node->safe_psql($db1, qq'GRANT USAGE ON FOREIGN SERVER $fdw_server to $user;'); +$node->safe_psql($db1, qq'GRANT ALL ON SCHEMA public to $user'); + +unlink($node->data_dir . '/pg_hba.conf'); +$node->append_conf( + 'pg_hba.conf', qq{ +local all all scram-sha-256 +host all all $hostaddr/32 scram-sha-256 +}); +$node->restart; + +# End of test setup + +$ENV{PGPASSWORD} = "pass"; + +$node->safe_psql($db1, qq'IMPORT FOREIGN SCHEMA public LIMIT TO(t) FROM SERVER $fdw_server INTO public ;', + connstr=>$connstr); + +my $ret = $node->safe_psql($db1, 'SELECT count(1) FROM t', + connstr=>$connstr); +is($ret, '10', 'SELECT count from fdw server returns 10'); + + +done_testing(); diff --git a/src/backend/libpq/auth-scram.c b/src/backend/libpq/auth-scram.c index 8c5b6d9c67..88a15cc0e5 100644 --- a/src/backend/libpq/auth-scram.c +++ b/src/backend/libpq/auth-scram.c @@ -101,6 +101,7 @@ #include "libpq/crypt.h" #include "libpq/sasl.h" #include "libpq/scram.h" +#include "miscadmin.h" static void scram_get_mechanisms(Port *port, StringInfo buf); static void *scram_init(Port *port, const char *selected_mech, @@ -144,6 +145,7 @@ typedef struct int iterations; char *salt; /* base64-encoded */ + uint8 ClientKey[SCRAM_MAX_KEY_LEN]; uint8 StoredKey[SCRAM_MAX_KEY_LEN]; uint8 ServerKey[SCRAM_MAX_KEY_LEN]; @@ -462,6 +464,13 @@ scram_exchange(void *opaq, const char *input, int inputlen, if (*output) *outputlen = strlen(*output); + if (result == PG_SASL_EXCHANGE_SUCCESS && state->state == SCRAM_AUTH_FINISHED) + { + memcpy(MyProcPort->scram_ClientKey, state->ClientKey, sizeof(MyProcPort->scram_ClientKey)); + memcpy(MyProcPort->scram_ServerKey, state->ServerKey, sizeof(MyProcPort->scram_ServerKey)); + MyProcPort->has_scram_keys = true; + } + return result; } @@ -1140,9 +1149,8 @@ static bool verify_client_proof(scram_state *state) { uint8 ClientSignature[SCRAM_MAX_KEY_LEN]; - uint8 ClientKey[SCRAM_MAX_KEY_LEN]; uint8 client_StoredKey[SCRAM_MAX_KEY_LEN]; - pg_hmac_ctx *ctx = pg_hmac_create(state->hash_type); + pg_hmac_ctx *ctx = pg_hmac_create(PG_SHA256); int i; const char *errstr = NULL; @@ -1173,10 +1181,10 @@ verify_client_proof(scram_state *state) /* Extract the ClientKey that the client calculated from the proof */ for (i = 0; i < state->key_length; i++) - ClientKey[i] = state->ClientProof[i] ^ ClientSignature[i]; + state->ClientKey[i] = state->ClientProof[i] ^ ClientSignature[i]; /* Hash it one more time, and compare with StoredKey */ - if (scram_H(ClientKey, state->hash_type, state->key_length, + if (scram_H(state->ClientKey, state->hash_type, state->key_length, client_StoredKey, &errstr) < 0) elog(ERROR, "could not hash stored key: %s", errstr); diff --git a/src/include/libpq/libpq-be.h b/src/include/libpq/libpq-be.h index 9109b2c334..4eb9e80523 100644 --- a/src/include/libpq/libpq-be.h +++ b/src/include/libpq/libpq-be.h @@ -18,6 +18,8 @@ #ifndef LIBPQ_BE_H #define LIBPQ_BE_H +#include "common/scram-common.h" + #include #ifdef USE_OPENSSL #include @@ -181,6 +183,13 @@ typedef struct Port int keepalives_count; int tcp_user_timeout; + /* + * SCRAM structures. + */ + uint8 scram_ClientKey[SCRAM_MAX_KEY_LEN]; + uint8 scram_ServerKey[SCRAM_MAX_KEY_LEN]; + bool has_scram_keys; /* true if the above two are valid */ + /* * GSSAPI structures. */ diff --git a/src/interfaces/libpq/fe-auth-scram.c b/src/interfaces/libpq/fe-auth-scram.c index 0bb820e0d9..7beb5a9d31 100644 --- a/src/interfaces/libpq/fe-auth-scram.c +++ b/src/interfaces/libpq/fe-auth-scram.c @@ -119,6 +119,8 @@ scram_init(PGconn *conn, return NULL; } + if (password) + { /* Normalize the password with SASLprep, if possible */ rc = pg_saslprep(password, &prep_password); if (rc == SASLPREP_OOM) @@ -138,6 +140,7 @@ scram_init(PGconn *conn, } } state->password = prep_password; + } return state; } @@ -775,6 +778,12 @@ calculate_client_proof(fe_scram_state *state, return false; } + if (state->conn->scram_client_key_binary) + { + memcpy(ClientKey, state->conn->scram_client_key_binary, SCRAM_MAX_KEY_LEN); + } + else + { /* * Calculate SaltedPassword, and store it in 'state' so that we can reuse * it later in verify_server_signature. @@ -783,15 +792,20 @@ calculate_client_proof(fe_scram_state *state, state->key_length, state->salt, state->saltlen, state->iterations, state->SaltedPassword, errstr) < 0 || - scram_ClientKey(state->SaltedPassword, state->hash_type, - state->key_length, ClientKey, errstr) < 0 || - scram_H(ClientKey, state->hash_type, state->key_length, - StoredKey, errstr) < 0) + scram_ClientKey(state->SaltedPassword, state->hash_type, + state->key_length, ClientKey, errstr) < 0) { /* errstr is already filled here */ pg_hmac_free(ctx); return false; } + } + + if (scram_H(ClientKey, state->hash_type, state->key_length, StoredKey, errstr) < 0) + { + pg_hmac_free(ctx); + return false; + } if (pg_hmac_init(ctx, StoredKey, state->key_length) < 0 || pg_hmac_update(ctx, @@ -841,6 +855,12 @@ verify_server_signature(fe_scram_state *state, bool *match, return false; } + if (state->conn->scram_server_key_binary) + { + memcpy(ServerKey, state->conn->scram_server_key_binary, SCRAM_MAX_KEY_LEN); + } + else + { if (scram_ServerKey(state->SaltedPassword, state->hash_type, state->key_length, ServerKey, errstr) < 0) { @@ -848,6 +868,7 @@ verify_server_signature(fe_scram_state *state, bool *match, pg_hmac_free(ctx); return false; } + } /* calculate ServerSignature */ if (pg_hmac_init(ctx, ServerKey, state->key_length) < 0 || diff --git a/src/interfaces/libpq/fe-auth.c b/src/interfaces/libpq/fe-auth.c index 20d3427e94..ef1c965cd5 100644 --- a/src/interfaces/libpq/fe-auth.c +++ b/src/interfaces/libpq/fe-auth.c @@ -559,7 +559,7 @@ pg_SASL_init(PGconn *conn, int payloadlen) * First, select the password to use for the exchange, complaining if * there isn't one and the selected SASL mechanism needs it. */ - if (conn->password_needed) + if (conn->password_needed && !conn->scram_client_key_binary) { password = conn->connhost[conn->whichhost].password; if (password == NULL) diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c index aaf87e8e88..464cefd901 100644 --- a/src/interfaces/libpq/fe-connect.c +++ b/src/interfaces/libpq/fe-connect.c @@ -22,6 +22,7 @@ #include #include +#include "common/base64.h" #include "common/ip.h" #include "common/link-canary.h" #include "common/scram-common.h" @@ -365,6 +366,12 @@ static const internalPQconninfoOption PQconninfoOptions[] = { "Load-Balance-Hosts", "", 8, /* sizeof("disable") = 8 */ offsetof(struct pg_conn, load_balance_hosts)}, + {"scram_client_key", NULL, NULL, NULL, "SCRAM-Client-Key", "D", SCRAM_MAX_KEY_LEN * 2, + offsetof(struct pg_conn, scram_client_key)}, + + {"scram_server_key", NULL, NULL, NULL, "SCRAM-Server-Key", "D", SCRAM_MAX_KEY_LEN * 2, + offsetof(struct pg_conn, scram_server_key)}, + /* Terminating entry --- MUST BE LAST */ {NULL, NULL, NULL, NULL, NULL, NULL, 0} @@ -1792,6 +1799,28 @@ pqConnectOptions2(PGconn *conn) else conn->target_server_type = SERVER_TYPE_ANY; + if (conn->scram_client_key) + { + int len; + + len = pg_b64_dec_len(strlen(conn->scram_client_key)); + conn->scram_client_key_len = len; + conn->scram_client_key_binary = malloc(len); + pg_b64_decode(conn->scram_client_key, strlen(conn->scram_client_key), + conn->scram_client_key_binary, len); + } + + if (conn->scram_server_key) + { + int len; + + len = pg_b64_dec_len(strlen(conn->scram_server_key)); + conn->scram_server_key_len = len; + conn->scram_server_key_binary = malloc(len); + pg_b64_decode(conn->scram_server_key, strlen(conn->scram_server_key), + conn->scram_server_key_binary, len); + } + /* * validate load_balance_hosts option, and set load_balance_type */ @@ -4703,6 +4732,8 @@ freePGconn(PGconn *conn) free(conn->rowBuf); free(conn->target_session_attrs); free(conn->load_balance_hosts); + free(conn->scram_client_key); + free(conn->scram_server_key); termPQExpBuffer(&conn->errorMessage); termPQExpBuffer(&conn->workBuffer); diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h index 08cc391cbd..17b81c81f4 100644 --- a/src/interfaces/libpq/libpq-int.h +++ b/src/interfaces/libpq/libpq-int.h @@ -427,6 +427,8 @@ struct pg_conn char *target_session_attrs; /* desired session properties */ char *require_auth; /* name of the expected auth method */ char *load_balance_hosts; /* load balance over hosts */ + char *scram_client_key; + char *scram_server_key; bool cancelRequest; /* true if this connection is used to send a * cancel request, instead of being a normal @@ -517,6 +519,10 @@ struct pg_conn AddrInfo *addr; /* the array of addresses for the currently * tried host */ bool send_appname; /* okay to send application_name? */ + size_t scram_client_key_len; + char *scram_client_key_binary; + size_t scram_server_key_len; + char *scram_server_key_binary; /* Miscellaneous stuff */ int be_pid; /* PID of backend --- needed for cancels */ -- 2.39.3 (Apple Git-146)