diff options
Diffstat (limited to 'src/interfaces/libpq/fe-auth.c')
| -rw-r--r-- | src/interfaces/libpq/fe-auth.c | 25 |
1 files changed, 20 insertions, 5 deletions
diff --git a/src/interfaces/libpq/fe-auth.c b/src/interfaces/libpq/fe-auth.c index 09012c562d0..540aba98b37 100644 --- a/src/interfaces/libpq/fe-auth.c +++ b/src/interfaces/libpq/fe-auth.c @@ -530,11 +530,26 @@ pg_SASL_init(PGconn *conn, int payloadlen) * nothing else has already been picked. If we add more mechanisms, a * more refined priority mechanism might become necessary. */ - if (conn->ssl_in_use && - conn->scram_channel_binding && - strlen(conn->scram_channel_binding) > 0 && - strcmp(mechanism_buf.data, SCRAM_SHA_256_PLUS_NAME) == 0) - selected_mechanism = SCRAM_SHA_256_PLUS_NAME; + if (strcmp(mechanism_buf.data, SCRAM_SHA_256_PLUS_NAME) == 0) + { + if (conn->ssl_in_use) + selected_mechanism = SCRAM_SHA_256_PLUS_NAME; + else + { + /* + * The server offered SCRAM-SHA-256-PLUS, but the connection + * is not SSL-encrypted. That's not sane. Perhaps SSL was + * stripped by a proxy? There's no point in continuing, + * because the server will reject the connection anyway if we + * try authenticate without channel binding even though both + * the client and server supported it. The SCRAM exchange + * checks for that, to prevent downgrade attacks. + */ + printfPQExpBuffer(&conn->errorMessage, + libpq_gettext("server offered SCRAM-SHA-256-PLUS authentication over a non-SSL connection\n")); + goto error; + } + } else if (strcmp(mechanism_buf.data, SCRAM_SHA_256_NAME) == 0 && !selected_mechanism) selected_mechanism = SCRAM_SHA_256_NAME; |