Accept SCRAM channel binding enabled clients

Add support to the SCRAM exchange for clients that support channel
binding, such as PostgreSQL version 11 and beyond.  If such a client
encounters a PgBouncer server that does not support channel binding,
it will send a channel binding flag 'y', meaning the client supports
channel binding but thinks the server does not.  But PgBouncer
erroneously did not accept that flag.  This would cause connections to
fail if a PostgreSQL version 11 client connects to a PgBouncer with
SCRAM authentication over SSL.

adapted from PostgreSQL 218b024a7ec866ec62abb5c2fb4eb9108bb5fc0f

Reported-by: Andrew Dunstan

diff --git a/include/bouncer.h b/include/bouncer.h
index 5f8fd2737352bbd781f063ac60a3c20a2f31916f..45795e0ee786917ffcdf3c62e4699d633a3c153e 100644 (file)
--- a/include/bouncer.h
+++ b/include/bouncer.h
@@ -396,6 +396,7 @@ struct PgSocket {
                char *server_nonce;
                char *server_first_message;
                uint8_t *SaltedPassword;
+               char cbind_flag;
                int iterations;
                char *salt;     /* base64-encoded */
                uint8_t StoredKey[32];  /* SHA256_DIGEST_LENGTH */

diff --git a/include/scram.h b/include/scram.h
index c45ebecf6db2504dd9585dfe927b802508c838bb..b52c83afa7c52e63c28d1f2d899bfd0423c288eb 100644 (file)
--- a/include/scram.h
+++ b/include/scram.h
@@ -57,6 +57,7 @@ bool verify_server_signature(ScramState *scram_state, const char *ServerSignatur
  */
 
 bool read_client_first_message(PgSocket *client, char *input,
+                              char *cbind_flag_p,
                               char **client_first_message_bare_p,
                               char **client_nonce_p);
 

diff --git a/src/client.c b/src/client.c
index 236b92434d2d0ef66cb22de73009abea4c56025c..acaa9a1b64c63eb7d7c67303dad5e2787b018dc8 100644 (file)
--- a/src/client.c
+++ b/src/client.c
@@ -532,6 +532,7 @@ static bool scram_client_first(PgSocket *client, uint32_t datalen, const uint8_t
        input = ibuf;
        slog_debug(client, "SCRAM client-first-message = \"%s\"", input);
        if (!read_client_first_message(client, input,
+                                      &client->scram_state.cbind_flag,
                                       &client->scram_state.client_first_message_bare,
                                       &client->scram_state.client_nonce))
                goto failed;

diff --git a/src/scram.c b/src/scram.c
index 10df2f960b5a70274d3a54755df337522ca129b7..d4e0abf1765e3f36ff1633cc07471286f4fa3268 100644 (file)
--- a/src/scram.c
+++ b/src/scram.c
@@ -560,12 +560,14 @@ bool verify_server_signature(ScramState *scram_state, const char *ServerSignatur
  */
 
 bool read_client_first_message(PgSocket *client, char *input,
+                              char *cbind_flag_p,
                               char **client_first_message_bare_p,
                               char **client_nonce_p)
 {
        char *client_first_message_bare = NULL;
        char *client_nonce = NULL;
 
+       *cbind_flag_p = *input;
        switch (*input) {
        case 'n':
                /* Client does not support channel binding */
@@ -657,12 +659,15 @@ bool read_client_final_message(PgSocket *client, const uint8_t *raw_input, char
        /*
         * Read channel-binding.  We don't support channel binding, so
         * it's expected to always be "biws", which is "n,,",
-        * base64-encoded.
+        * base64-encoded, or "eSws", which is "y,,".  We also have to
+        * check whether the flag is the same one that the client
+        * originally sent.
         */
        channel_binding = read_attr_value(client, &input, 'c');
        if (channel_binding == NULL)
                goto failed;
-       if (strcmp(channel_binding, "biws") != 0) {
+       if (!(strcmp(channel_binding, "biws") == 0 && client->scram_state.cbind_flag == 'n') &&
+           !(strcmp(channel_binding, "eSws") == 0 && client->scram_state.cbind_flag == 'y')) {
                slog_error(client, "unexpected SCRAM channel-binding attribute in client-final-message");
                goto failed;
        }

diff --git a/test/ssl/test.sh b/test/ssl/test.sh
index 2f444b6406c86db8e5ebaccf77954ea60554bb65..0cddf88c667ca1e812029fb55430c00a55b57c47 100755 (executable)
--- a/test/ssl/test.sh
+++ b/test/ssl/test.sh
@@ -34,6 +34,21 @@ pgctl() {
 
 ulimit -c unlimited
 
+# System configuration checks
+SED_ERE_OP='-E'
+case `uname` in
+Linux)
+       SED_ERE_OP='-r'
+       ;;
+esac
+
+pg_majorversion=$(initdb --version | sed -n $SED_ERE_OP 's/.* ([0-9]+).*/\1/p')
+if test $pg_majorversion -ge 10; then
+       pg_supports_scram=true
+else
+       pg_supports_scram=false
+fi
+
 stopit() {
        local pid
        if test -f "$1"; then
@@ -139,6 +154,9 @@ runtest() {
        status=$?
        if [ $status -eq 0 ]; then
                echo "ok"
+       elif [ $status -eq 77 ]; then
+               echo "skipped"
+               status=0
        else
                echo "FAILED"
                cat $LOGDIR/$1.log | sed 's/^/# /'
@@ -159,7 +177,7 @@ psql_pg() {
 }
 
 psql_bouncer() {
-       PGUSER=bouncer psql -X "$@"
+       PGUSER=bouncer PGPASSWORD=zzz psql -X "$@"
 }
 
 # server_lifetime
@@ -242,12 +260,27 @@ test_client_ssl_auth() {
        return $rc
 }
 
+test_client_ssl_scram() {
+       $pg_supports_scram || return 77
+
+       reconf_bouncer "auth_type = scram-sha-256" "server_tls_sslmode = prefer" \
+               "client_tls_sslmode = require" \
+               "client_tls_key_file = TestCA1/sites/01-localhost.key" \
+               "client_tls_cert_file = TestCA1/sites/01-localhost.crt"
+       reconf_pgsql "ssl=on" "ssl_ca_file='root.crt'"
+       psql_bouncer -q -d "dbname=p0 sslmode=verify-full sslrootcert=TestCA1/ca.crt" -c "select 'client-ssl-connect'" | tee tmp/test.tmp 2>&1
+       grep -q "client-ssl-connect"  tmp/test.tmp
+       rc=$?
+       return $rc
+}
+
 testlist="
 test_server_ssl
 test_server_ssl_verify
 test_server_ssl_pg_auth
 test_client_ssl
 test_client_ssl_auth
+test_client_ssl_scram
 "
 if [ $# -gt 0 ]; then
        testlist="$*"