context: add library.use-fallback option

Normally, when loading a plugin feature, often a library.name property
is given as well. If the feature to load is not explicitly listed in
context.spa-libs, the library.name is used a fallback library.

Add an option to ignore this library.name and only use the
context.spa-libs entries. This makes it possible to only load explicitly
listed features in the config file and makes it possible to lock down
what plugins can be loaded.

Set the option to true by default for now, which keeps the existing
behaviour of using the fallback library. Add some more entries to the
context.spa-libs in case the option is switched off to make things
work.

Set the option to false for the minimal.conf.

doc/dox/config/pipewire.conf.5.md

@@ -288,6 +288,12 @@ Default video rate denominator
 @PAR@ pipewire.conf  library.name.system = support/libspa-support
 The name of the shared library to use for the system functions for the main thread.
 
+@PAR@ pipewire.conf  library.use-fallback = true
+When a plugin feature is not listed in context.spa-libs, a predefined fallback
+plugin location is used by default. If this option is set to false, only plugin
+features explicitly listed in context.spa-libs will be loadable. This can be used
+to lock down what plugins that can be loaded.
+
 @PAR@ pipewire.conf  link.max-buffers = 64
 The maximum number of buffers to negotiate between nodes. Note that version < 3 clients
 can only support 16 buffers. More buffers is almost always worse than less, latency

src/daemon/minimal.conf.in

@@ -13,6 +13,7 @@ context.properties = {
     #library.name.system                   = support/libspa-support
     #context.data-loop.library.name.system = support/libspa-support
     #support.dbus                          = true
+    library.use-fallback                   = false
     #link.max-buffers                      = 64
     link.max-buffers                       = 16                       # version < 3 clients can't handle more
     #mem.warn-mlock                        = false
@@ -70,10 +71,28 @@ context.spa-libs = {
     # regular expression to a library name that should contain
     # that factory.
     #
+    support.*       = support/libspa-support
     audio.convert.* = audioconvert/libspa-audioconvert
     audio.adapt     = audioconvert/libspa-audioconvert
     api.alsa.*      = alsa/libspa-alsa
-    support.*       = support/libspa-support
+    #api.v4l2.*      = v4l2/libspa-v4l2
+    #api.libcamera.* = libcamera/libspa-libcamera
+    #api.bluez5.*    = bluez5/libspa-bluez5
+    #api.vulkan.*    = vulkan/libspa-vulkan
+    #video.convert.* = videoconvert/libspa-videoconvert
+    #video.adapt     = videoconvert/libspa-videoconvert
+    audio.mixer.*   = audiomixer/libspa-audiomixer
+    control.mixer   = control/libspa-mixer
+    #audio.aec       = aec/libspa-aec-webrtc
+    #filter.graph.plugin.ffmpeg  = filter-graph/libspa-filter-graph-plugin-ffmpeg
+    #filter.graph.plugin.onnx    = filter-graph/libspa-filter-graph-plugin-onnx
+    #filter.graph.plugin.pipe    = blocked
+    #filter.graph.plugin.ebur128 = filter-graph/libspa-filter-graph-plugin-ebur128
+    #filter.graph.plugin.sofa    = filter-graph/libspa-filter-graph-plugin-sofa
+    #filter.graph.plugin.ladspa  = filter-graph/libspa-filter-graph-plugin-ladspa
+    #filter.graph.plugin.lv2     = filter-graph/libspa-filter-graph-plugin-lv2
+    #filter.graph.plugin.builtin = filter-graph/libspa-filter-graph-plugin-builtin
+    #filter.graph    = filter-graph/libspa-filter-graph
 }
 
 context.modules = [

src/daemon/pipewire-pulse.conf.in

@@ -15,17 +15,29 @@ context.properties = {
     #mem.mlock-all   = false
     #log.level       = 2
     #rlimit.nofile   = -1
+    #library.use-fallback = true
 
     #default.clock.quantum-limit = 8192
 }
 
 context.spa-libs = {
-    audio.convert.* = audioconvert/libspa-audioconvert
     support.*       = support/libspa-support
+    audio.convert.* = audioconvert/libspa-audioconvert
+    audio.adapt     = audioconvert/libspa-audioconvert
+    audio.mixer     = audiomixer/libspa-audiomixer
+    audio.aec       = aec/libspa-aec-webrtc
     # because the pulse server allows dynamic loading of streams and modules
-    # inside the server, we must be careful with the filter-graph. Only allow
+    # inside the server, we must be careful with the filter-graph.
-    # LADSPA filters.
+    #filter.graph.plugin.ffmpeg  = filter-graph/libspa-filter-graph-plugin-ffmpeg
-    filter.graph.plugin.pipe = blocked
+    #filter.graph.plugin.onnx    = filter-graph/libspa-filter-graph-plugin-onnx
+    #filter.graph.plugin.pipe    = filter-graph/libspa-filter-graph-plugin-pipe
+    filter.graph.plugin.pipe    = blocked
+    #filter.graph.plugin.ebur128 = filter-graph/libspa-filter-graph-plugin-ebur128
+    #filter.graph.plugin.sofa    = filter-graph/libspa-filter-graph-plugin-sofa
+    filter.graph.plugin.ladspa  = filter-graph/libspa-filter-graph-plugin-ladspa
+    #filter.graph.plugin.lv2     = filter-graph/libspa-filter-graph-plugin-lv2
+    filter.graph.plugin.builtin = filter-graph/libspa-filter-graph-plugin-builtin
+    filter.graph    = filter-graph/libspa-filter-graph
 }
 
 context.modules = [

src/daemon/pipewire.conf.in

@@ -12,6 +12,7 @@ context.properties = {
     ## Configure properties in the system.
     #library.name.system                   = support/libspa-support
     #context.data-loop.library.name.system = support/libspa-support
+    #library.use-fallback                  = true
     #support.dbus                          = true
     #link.max-buffers                      = 64
     link.max-buffers                       = 16                       # version < 3 clients can't handle more
@@ -75,17 +76,29 @@ context.spa-libs = {
     # regular expression to a library name that should contain
     # that factory.
     #
+    support.*       = support/libspa-support
     audio.convert.* = audioconvert/libspa-audioconvert
-    avb.*           = avb/libspa-avb
+    audio.adapt     = audioconvert/libspa-audioconvert
     api.alsa.*      = alsa/libspa-alsa
     api.v4l2.*      = v4l2/libspa-v4l2
     api.libcamera.* = libcamera/libspa-libcamera
     api.bluez5.*    = bluez5/libspa-bluez5
-    api.vulkan.*    = vulkan/libspa-vulkan
+    #api.vulkan.*    = vulkan/libspa-vulkan
-    api.jack.*      = jack/libspa-jack
-    support.*       = support/libspa-support
     video.convert.* = videoconvert/libspa-videoconvert
-    #filter.graph    = filter-graph/libspa-filter-graph
+    video.adapt     = videoconvert/libspa-videoconvert
+    audio.mixer.*   = audiomixer/libspa-audiomixer
+    control.mixer   = control/libspa-mixer
+    audio.aec       = aec/libspa-aec-webrtc
+    #filter.graph.plugin.ffmpeg  = filter-graph/libspa-filter-graph-plugin-ffmpeg
+    filter.graph.plugin.onnx    = filter-graph/libspa-filter-graph-plugin-onnx
+    #filter.graph.plugin.pipe    = filter-graph/libspa-filter-graph-plugin-pipe
+    filter.graph.plugin.pipe    = blocked
+    filter.graph.plugin.ebur128 = filter-graph/libspa-filter-graph-plugin-ebur128
+    filter.graph.plugin.sofa    = filter-graph/libspa-filter-graph-plugin-sofa
+    filter.graph.plugin.ladspa  = filter-graph/libspa-filter-graph-plugin-ladspa
+    filter.graph.plugin.lv2     = filter-graph/libspa-filter-graph-plugin-lv2
+    filter.graph.plugin.builtin = filter-graph/libspa-filter-graph-plugin-builtin
+    filter.graph    = filter-graph/libspa-filter-graph
     #videotestsrc   = videotestsrc/libspa-videotestsrc
     #audiotestsrc   = audiotestsrc/libspa-audiotestsrc
 }

src/pipewire/context.c

@@ -152,7 +152,6 @@ static struct spa_handle *impl_plugin_loader_load(void *object, const char *fact
 		errno = EINVAL;
 		return NULL;
 	}
-
 	return pw_context_load_spa_handle(&impl->this, factory_name, info);
 }
 
@@ -1057,20 +1056,23 @@ struct spa_handle *pw_context_load_spa_handle(struct pw_context *context,
 		const char *factory_name,
 		const struct spa_dict *info)
 {
-	const char *lib;
+	const char *lib, *fallback_lib = NULL;
 	const struct spa_support *support;
 	uint32_t n_support;
 	struct spa_handle *handle;
 
-	pw_log_debug("%p: load factory %s", context, factory_name);
+	if (info != NULL)
+		fallback_lib = spa_dict_lookup(info, SPA_KEY_LIBRARY_NAME);
+
+	pw_log_info("%p: load factory %s fallback:%s", context, factory_name, fallback_lib);
 
 	lib = pw_context_find_spa_lib(context, factory_name);
-	if (lib == NULL && info != NULL)
+	if (lib == NULL && context->settings.use_fallback)
-		lib = spa_dict_lookup(info, SPA_KEY_LIBRARY_NAME);
+		lib = fallback_lib;
 	if (lib == NULL || spa_streq(lib, "blocked")) {
 		errno = lib ? EPERM : ENOENT;
-		pw_log_warn("%p: no library for %s: %m",
+		pw_log_warn("%p: no library for %s (fallback: %s): %m",
-				context, factory_name);
+				context, factory_name, fallback_lib);
 		return NULL;
 	}
 

src/pipewire/private.h

@@ -52,6 +52,7 @@ struct settings {
 	unsigned int clock_power_of_two_quantum:1;
 	unsigned int check_quantum:1;
 	unsigned int check_rate:1;
+	unsigned int use_fallback:1;
 #define CLOCK_RATE_UPDATE_MODE_HARD 0
 #define CLOCK_RATE_UPDATE_MODE_SOFT 1
 	int clock_rate_update_mode;

src/pipewire/settings.c

@@ -37,6 +37,7 @@
 #define DEFAULT_MEM_ALLOW_MLOCK			true
 #define DEFAULT_CHECK_QUANTUM			false
 #define DEFAULT_CHECK_RATE			false
+#define DEFAULT_USE_FALLBACK			true
 
 struct impl {
 	struct pw_context *context;
@@ -227,6 +228,7 @@ void pw_settings_init(struct pw_context *this)
 
 	d->check_quantum = get_default_bool(p, "settings.check-quantum", DEFAULT_CHECK_QUANTUM);
 	d->check_rate = get_default_bool(p, "settings.check-rate", DEFAULT_CHECK_RATE);
+	d->use_fallback = get_default_bool(p, "library.use-fallback", DEFAULT_USE_FALLBACK);
 
 	d->link_max_buffers = SPA_MAX(d->link_max_buffers, 1u);