io_uring/net: allow filtering on IORING_OP_SOCKET data

Example population method for the BPF based opcode filtering. This
exposes the socket family, type, and protocol to a registered BPF
filter. This in turn enables the filter to make decisions based on
what was passed in to the IORING_OP_SOCKET request type.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: axboe

include/uapi/linux/io_uring/bpf_filter.h

@@ -16,6 +16,13 @@ struct io_uring_bpf_ctx {
 	__u8	sqe_flags;
 	__u8	pdu_size;	/* size of aux data for filter */
 	__u8	pad[5];
+	union {
+		struct {
+			__u32	family;
+			__u32	type;
+			__u32	protocol;
+		} socket;
+	};
 };
 
 enum {

io_uring/bpf_filter.c

@@ -30,6 +30,17 @@ static void io_uring_populate_bpf_ctx(struct io_uring_bpf_ctx *bctx,
 	/* clear residual, anything from pdu_size and below */
 	memset((void *) bctx + offsetof(struct io_uring_bpf_ctx, pdu_size), 0,
 		sizeof(*bctx) - offsetof(struct io_uring_bpf_ctx, pdu_size));
+
+	/*
+	 * Opcodes can provide a handler fo populating more data into bctx,
+	 * for filters to use.
+	 */
+	switch (req->opcode) {
+	case IORING_OP_SOCKET:
+		bctx->pdu_size = sizeof(bctx->socket);
+		io_socket_bpf_populate(bctx, req);
+		break;
+	}
 }
 
 /*

io_uring/net.c

@@ -1699,6 +1699,15 @@ int io_accept(struct io_kiocb *req, unsigned int issue_flags)
 	return IOU_COMPLETE;
 }
 
+void io_socket_bpf_populate(struct io_uring_bpf_ctx *bctx, struct io_kiocb *req)
+{
+	struct io_socket *sock = io_kiocb_to_cmd(req, struct io_socket);
+
+	bctx->socket.family = sock->domain;
+	bctx->socket.type = sock->type;
+	bctx->socket.protocol = sock->protocol;
+}
+
 int io_socket_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
 	struct io_socket *sock = io_kiocb_to_cmd(req, struct io_socket);

io_uring/net.h

@@ -3,6 +3,7 @@
 #include <linux/net.h>
 #include <linux/uio.h>
 #include <linux/io_uring_types.h>
+#include <uapi/linux/io_uring/bpf_filter.h>
 
 struct io_async_msghdr {
 #if defined(CONFIG_NET)
@@ -44,6 +45,7 @@ int io_accept(struct io_kiocb *req, unsigned int issue_flags);
 
 int io_socket_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
 int io_socket(struct io_kiocb *req, unsigned int issue_flags);
+void io_socket_bpf_populate(struct io_uring_bpf_ctx *bctx, struct io_kiocb *req);
 
 int io_connect_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
 int io_connect(struct io_kiocb *req, unsigned int issue_flags);
@@ -64,4 +66,8 @@ void io_netmsg_cache_free(const void *entry);
 static inline void io_netmsg_cache_free(const void *entry)
 {
 }
+static inline void io_socket_bpf_populate(struct io_uring_bpf_ctx *bctx,
+					  struct io_kiocb *req)
+{
+}
 #endif