From bbf11cd5f92064c7c8af61ad4d9ff41f3a039abc Mon Sep 17 00:00:00 2001 From: Alban Crequy Date: Mon, 21 Jul 2014 17:34:08 +0100 Subject: config: add new limit: pending_fd_timeout This is one of four commits needed to address CVE-2014-3637. When a file descriptor is passed to dbus-daemon, the associated D-Bus message might not be fully sent to dbus-daemon yet. Dbus-daemon keeps the file descriptor in the DBusMessageLoader of the connection, waiting for the rest of the message. If the client stops sending the remaining bytes, dbus-daemon will wait forever and keep that file descriptor. This patch adds pending_fd_timeout (milliseconds) in the configuration to disconnect a connection after a timeout when a file descriptor was sent but not the remaining message. Bug: https://bugs.freedesktop.org/show_bug.cgi?id=80559 Reviewed-by: Simon McVittie --- bus/bus.c | 6 ++++++ bus/bus.h | 2 ++ bus/config-parser.c | 12 ++++++++++++ bus/session.conf.in | 1 + doc/dbus-daemon.1.xml.in | 4 ++++ 5 files changed, 25 insertions(+) diff --git a/bus/bus.c b/bus/bus.c index a3dce244..35d40754 100644 --- a/bus/bus.c +++ b/bus/bus.c @@ -1240,6 +1240,12 @@ bus_context_get_auth_timeout (BusContext *context) return context->limits.auth_timeout; } +int +bus_context_get_pending_fd_timeout (BusContext *context) +{ + return context->limits.pending_fd_timeout; +} + int bus_context_get_max_completed_connections (BusContext *context) { diff --git a/bus/bus.h b/bus/bus.h index 400c9d01..7d0b3697 100644 --- a/bus/bus.h +++ b/bus/bus.h @@ -54,6 +54,7 @@ typedef struct long max_message_unix_fds; /**< Max number of unix fds of a single message*/ int activation_timeout; /**< How long to wait for an activation to time out */ int auth_timeout; /**< How long to wait for an authentication to time out */ + int pending_fd_timeout; /**< How long to wait for a D-Bus message with a fd to time out */ int max_completed_connections; /**< Max number of authorized connections */ int max_incomplete_connections; /**< Max number of incomplete connections */ int max_connections_per_user; /**< Max number of connections auth'd as same user */ @@ -106,6 +107,7 @@ BusClientPolicy* bus_context_create_client_policy (BusContext DBusError *error); int bus_context_get_activation_timeout (BusContext *context); int bus_context_get_auth_timeout (BusContext *context); +int bus_context_get_pending_fd_timeout (BusContext *context); int bus_context_get_max_completed_connections (BusContext *context); int bus_context_get_max_incomplete_connections (BusContext *context); int bus_context_get_max_connections_per_user (BusContext *context); diff --git a/bus/config-parser.c b/bus/config-parser.c index 814725a1..7bc9c019 100644 --- a/bus/config-parser.c +++ b/bus/config-parser.c @@ -439,6 +439,11 @@ bus_config_parser_new (const DBusString *basedir, * password) is allowed, then potentially it has to be quite long. */ parser->limits.auth_timeout = 5000; /* 5 seconds */ + + /* Do not allow a fd to stay forever in dbus-daemon + * https://bugs.freedesktop.org/show_bug.cgi?id=80559 + */ + parser->limits.pending_fd_timeout = 150000; /* 2.5 minutes */ parser->limits.max_incomplete_connections = 64; parser->limits.max_connections_per_user = 256; @@ -1902,6 +1907,12 @@ set_limit (BusConfigParser *parser, must_be_int = TRUE; parser->limits.auth_timeout = value; } + else if (strcmp (name, "pending_fd_timeout") == 0) + { + must_be_positive = TRUE; + must_be_int = TRUE; + parser->limits.pending_fd_timeout = value; + } else if (strcmp (name, "reply_timeout") == 0) { must_be_positive = TRUE; @@ -3108,6 +3119,7 @@ limits_equal (const BusLimits *a, || a->max_message_unix_fds == b->max_message_unix_fds || a->activation_timeout == b->activation_timeout || a->auth_timeout == b->auth_timeout + || a->pending_fd_timeout == b->pending_fd_timeout || a->max_completed_connections == b->max_completed_connections || a->max_incomplete_connections == b->max_incomplete_connections || a->max_connections_per_user == b->max_connections_per_user diff --git a/bus/session.conf.in b/bus/session.conf.in index d4730363..cfe9544f 100644 --- a/bus/session.conf.in +++ b/bus/session.conf.in @@ -53,6 +53,7 @@ limit is also relatively low --> 120000 240000 + 150000 100000 10000 100000 diff --git a/doc/dbus-daemon.1.xml.in b/doc/dbus-daemon.1.xml.in index 7b7f4a1b..cd7942c3 100644 --- a/doc/dbus-daemon.1.xml.in +++ b/doc/dbus-daemon.1.xml.in @@ -528,6 +528,10 @@ Available limit names are: "auth_timeout" : milliseconds (thousandths) a connection is given to authenticate + "pending_fd_timeout" : milliseconds (thousandths) a + fd is given to be transmitted to + dbus-daemon before disconnecting the + connection "max_completed_connections" : max number of authenticated connections "max_incomplete_connections" : max number of unauthenticated connections -- cgit v1.2.3