Re: [RFC PATCH v2 00/11] KEYS: Sanitize the garbage collector

[David Howells <dhowells@redhat.com>]

Jarkko Sakkinen <jarkko@kernel.org> wrote:

> > Actually, it can be done if the rxrpc and rxrpc_s key types are moved out
> > into their own module upon which rxrpc.ko depends.
> 
> Hmm... I'll experiment with this, thanks. This was useful.

It's not entirely trivial.  I've attached a patch that makes a start on it,
but it needs access to bits of the security class implementations (rxkad and
rxgk).  Those bits only parse the key (and in the case of rxgk access the krb5
code), so in theory it should be possible to extract them out.

One thing that needs to be considered, though, is the security class selected
should really be up to the application, not merely switched on by the
security_id.  This is one of the reasons I would like to add an add_key2()
syscall that adds an additional parameter string argument.

David
---
commit 365e715b91b9b2ac3030f51c31ff4de8f24a4e19
Author: David Howells <dhowells@redhat.com>
Date:   Tue Nov 3 14:15:39 2026 +0000

    rxrpc: Move key types to own module
    
    Move the rxrpc and rxrpc_s key types to their own module so that if keys
    pin the module that implements the type, they don't cause outstanding
    connections to make the module unremovable.
    
    Signed-off-by: David Howells <dhowells@redhat.com>

diff --git a/net/Makefile b/net/Makefile
index 5b2dd7f07a85..f543097c89b9 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -30,7 +30,7 @@ obj-$(CONFIG_LAPB)		+= lapb/
 obj-$(CONFIG_CAN)		+= can/
 obj-$(CONFIG_BT)		+= bluetooth/
 obj-$(CONFIG_SUNRPC)		+= sunrpc/
-obj-$(CONFIG_AF_RXRPC)		+= rxrpc/
+obj-$(CONFIG_RXRPC_KEYS)	+= rxrpc/
 obj-$(CONFIG_AF_KCM)		+= kcm/
 obj-$(CONFIG_STREAM_PARSER)	+= strparser/
 obj-$(CONFIG_ATM)		+= atm/
diff --git a/net/rxrpc/Kconfig b/net/rxrpc/Kconfig
index 2cebb666dc07..ffd42d71f85a 100644
--- a/net/rxrpc/Kconfig
+++ b/net/rxrpc/Kconfig
@@ -3,6 +3,14 @@
 # RxRPC session sockets
 #
 
+config RXRPC_KEYS
+	tristate "RxRPC key types"
+	select CRYPTO
+	select CRYPTO_LIB_DES if RXKAD
+	select KEYS
+	help
+	  Say Y or M here to include support for rxrpc and rxrpc_s key types.
+
 config AF_RXRPC
 	tristate "RxRPC session sockets"
 	depends on INET
@@ -10,6 +18,7 @@ config AF_RXRPC
 	select CRYPTO_LIB_DES if RXKAD
 	select KEYS
 	select NET_UDP_TUNNEL
+	select RXRPC_KEYS
 	help
 	  Say Y or M here to include support for RxRPC session sockets (just
 	  the transport part, not the presentation part: (un)marshalling is
diff --git a/net/rxrpc/Makefile b/net/rxrpc/Makefile
index f994f9f30a29..196e0ce085ba 100644
--- a/net/rxrpc/Makefile
+++ b/net/rxrpc/Makefile
@@ -3,6 +3,7 @@
 # Makefile for Linux kernel RxRPC
 #
 
+obj-$(CONFIG_RXRPC_KEYS) += rxrpc_keys.o
 obj-$(CONFIG_AF_RXRPC) += rxrpc.o
 
 rxrpc-y := \
@@ -19,7 +20,6 @@ rxrpc-y := \
 	input_rack.o \
 	insecure.o \
 	io_thread.o \
-	key.o \
 	local_event.o \
 	local_object.o \
 	misc.o \
@@ -32,7 +32,6 @@ rxrpc-y := \
 	rtt.o \
 	security.o \
 	sendmsg.o \
-	server_key.o \
 	skbuff.o \
 	txbuf.o \
 	utils.o
@@ -45,5 +44,9 @@ rxrpc-$(CONFIG_RXGK) += \
 	rxgk_app.o \
 	rxgk_kdf.o
 
+rxrpc_keys-y := \
+	key.o \
+	server_key.o
+
 obj-$(CONFIG_RXPERF) += rxperf.o
 obj-$(CONFIG_KUNIT) += tests/
diff --git a/net/rxrpc/key.c b/net/rxrpc/key.c
index cbd26da44951..c353a4304788 100644
--- a/net/rxrpc/key.c
+++ b/net/rxrpc/key.c
@@ -893,3 +893,39 @@ static long rxrpc_read(const struct key *key,
 	_leave(" = %zu", size);
 	return size;
 }
+
+/*
+ * initialise and register the RxRPC protocol
+ */
+static int __init rxrpc_keys_init(void)
+{
+	int ret;
+
+	ret = register_key_type(&key_type_rxrpc);
+	if (ret < 0) {
+		pr_crit("Cannot register client key type\n");
+		goto error_key_type;
+	}
+
+	ret = register_key_type(&key_type_rxrpc_s);
+	if (ret < 0) {
+		pr_crit("Cannot register server key type\n");
+		goto error_key_type_s;
+	}
+
+	return 0;
+
+error_key_type_s:
+	unregister_key_type(&key_type_rxrpc);
+error_key_type:
+	return ret;
+}
+
+static void __exit rxrpc_keys_exit(void)
+{
+	unregister_key_type(&key_type_rxrpc_s);
+	unregister_key_type(&key_type_rxrpc);
+}
+
+module_init(rxrpc_keys_init);
+module_exit(rxrpc_keys_exit);
diff --git a/net/rxrpc/server_key.c b/net/rxrpc/server_key.c
index 3efe104b1930..b5e60a3364ad 100644
--- a/net/rxrpc/server_key.c
+++ b/net/rxrpc/server_key.c
@@ -42,6 +42,7 @@ struct key_type key_type_rxrpc_s = {
 	.destroy	= rxrpc_destroy_s,
 	.describe	= rxrpc_describe_s,
 };
+EXPORT_SYMBOL(key_type_rxrpc_s);
 
 /*
  * Vet the description for an RxRPC server key.