[PATCH 05/20] io_uring/zcrx: implement socket registration

[David Wei <dw@davidwei.uk>]

From: Pavel Begunkov <asml.silence@gmail.com>

We want userspace to explicitly list all sockets it'll be using with a
particular zc ifq, so we can properly configure them, e.g. binding the
sockets to the corresponding interface and setting steering rules. We'll
also need it to better control ifq lifetime and for
termination / unregistration purposes.

TODO: remove zc_rx_idx from struct socket, and uapi is likely to change

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David Wei <dw@davidwei.uk>
---
 include/linux/net.h           |  2 ++
 include/uapi/linux/io_uring.h |  7 ++++
 io_uring/io_uring.c           |  6 ++++
 io_uring/net.c                | 19 +++++++++++
 io_uring/zc_rx.c              | 63 +++++++++++++++++++++++++++++++++++
 io_uring/zc_rx.h              | 17 ++++++++++
 net/socket.c                  |  1 +
 7 files changed, 115 insertions(+)

diff --git a/include/linux/net.h b/include/linux/net.h
index c9b4a63791a4..867061a91d30 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -126,6 +126,8 @@ struct socket {
 	const struct proto_ops	*ops; /* Might change with IPV6_ADDRFORM or MPTCP. */
 
 	struct socket_wq	wq;
+
+	unsigned		zc_rx_idx;
 };
 
 /*
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index ae5608bcd785..917d0025cc94 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -550,6 +550,7 @@ enum {
 
 	/* register a network interface queue for zerocopy */
 	IORING_REGISTER_ZC_RX_IFQ		= 26,
+	IORING_REGISTER_ZC_RX_SOCK		= 27,
 
 	/* this goes last */
 	IORING_REGISTER_LAST,
@@ -788,6 +789,12 @@ struct io_uring_zc_rx_ifq_reg {
 	struct io_rbuf_cqring_offsets cq_off;
 };
 
+struct io_uring_zc_rx_sock_reg {
+	__u32	sockfd;
+	__u32	zc_rx_ifq_idx;
+	__u32	__resv[2];
+};
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index f06e9ed397da..e24e2c308a8a 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -4549,6 +4549,12 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
 			break;
 		ret = io_register_zc_rx_ifq(ctx, arg);
 		break;
+	case IORING_REGISTER_ZC_RX_SOCK:
+		ret = -EINVAL;
+		if (!arg || nr_args != 1)
+			break;
+		ret = io_register_zc_rx_sock(ctx, arg);
+		break;
 	default:
 		ret = -EINVAL;
 		break;
diff --git a/io_uring/net.c b/io_uring/net.c
index 7a8e298af81b..fc0b7936971d 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -955,6 +955,25 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 	return ret;
 }
 
+static __maybe_unused
+struct io_zc_rx_ifq *io_zc_verify_sock(struct io_kiocb *req,
+					struct socket *sock)
+{
+	unsigned token = READ_ONCE(sock->zc_rx_idx);
+	unsigned ifq_idx = token >> IO_ZC_IFQ_IDX_OFFSET;
+	unsigned sock_idx = token & IO_ZC_IFQ_IDX_MASK;
+	struct io_zc_rx_ifq *ifq;
+
+	if (ifq_idx)
+		return NULL;
+	ifq = req->ctx->ifq;
+	if (!ifq || sock_idx >= ifq->nr_sockets)
+		return NULL;
+	if (ifq->sockets[sock_idx] != req->file)
+		return NULL;
+	return ifq;
+}
+
 void io_send_zc_cleanup(struct io_kiocb *req)
 {
 	struct io_sr_msg *zc = io_kiocb_to_cmd(req, struct io_sr_msg);
diff --git a/io_uring/zc_rx.c b/io_uring/zc_rx.c
index 85180c3044d8..b5266a67395e 100644
--- a/io_uring/zc_rx.c
+++ b/io_uring/zc_rx.c
@@ -11,6 +11,7 @@
 #include "io_uring.h"
 #include "kbuf.h"
 #include "zc_rx.h"
+#include "rsrc.h"
 
 typedef int (*bpf_op_t)(struct net_device *dev, struct netdev_bpf *bpf);
 
@@ -129,12 +130,74 @@ int io_register_zc_rx_ifq(struct io_ring_ctx *ctx,
 int io_unregister_zc_rx_ifq(struct io_ring_ctx *ctx)
 {
 	struct io_zc_rx_ifq *ifq = ctx->ifq;
+	int i;
 
 	if (!ifq)
 		return -EINVAL;
 
+	for (i = 0; i < ifq->nr_sockets; i++)
+		fput(ifq->sockets[i]);
+
 	ctx->ifq = NULL;
 	io_zc_rx_ifq_free(ifq);
 	return 0;
 }
+
+int io_register_zc_rx_sock(struct io_ring_ctx *ctx,
+			   struct io_uring_zc_rx_sock_reg __user *arg)
+{
+	struct io_uring_zc_rx_sock_reg sr;
+	struct io_zc_rx_ifq *ifq;
+	struct socket *sock;
+	struct file *file;
+	int ret = -EEXIST;
+	int idx;
+
+	if (copy_from_user(&sr, arg, sizeof(sr)))
+		return -EFAULT;
+	if (sr.__resv[0] || sr.__resv[1])
+		return -EINVAL;
+	if (sr.zc_rx_ifq_idx != 0 || !ctx->ifq)
+		return -EINVAL;
+
+	ifq = ctx->ifq;
+	if (ifq->nr_sockets >= ARRAY_SIZE(ifq->sockets))
+		return -EINVAL;
+
+	BUILD_BUG_ON(ARRAY_SIZE(ifq->sockets) > IO_ZC_IFQ_IDX_MASK);
+
+	file = fget(sr.sockfd);
+	if (!file)
+		return -EBADF;
+
+	if (io_file_need_scm(file)) {
+		fput(file);
+		return -EBADF;
+	}
+
+	sock = sock_from_file(file);
+	if (unlikely(!sock || !sock->sk)) {
+		fput(file);
+		return -ENOTSOCK;
+	}
+
+	idx = ifq->nr_sockets;
+	lock_sock(sock->sk);
+	if (!sock->zc_rx_idx) {
+		unsigned token;
+
+		token = idx + (sr.zc_rx_ifq_idx << IO_ZC_IFQ_IDX_OFFSET);
+		WRITE_ONCE(sock->zc_rx_idx, token);
+		ret = 0;
+	}
+	release_sock(sock->sk);
+
+	if (ret) {
+		fput(file);
+		return -EINVAL;
+	}
+	ifq->sockets[idx] = file;
+	ifq->nr_sockets++;
+	return 0;
+}
 #endif
diff --git a/io_uring/zc_rx.h b/io_uring/zc_rx.h
index 5f6d80c1c2b8..ab25f8dbb433 100644
--- a/io_uring/zc_rx.h
+++ b/io_uring/zc_rx.h
@@ -2,6 +2,13 @@
 #ifndef IOU_ZC_RX_H
 #define IOU_ZC_RX_H
 
+#include <linux/io_uring_types.h>
+#include <linux/skbuff.h>
+
+#define IO_ZC_MAX_IFQ_SOCKETS		16
+#define IO_ZC_IFQ_IDX_OFFSET		16
+#define IO_ZC_IFQ_IDX_MASK		((1U << IO_ZC_IFQ_IDX_OFFSET) - 1)
+
 struct io_zc_rx_ifq {
 	struct io_ring_ctx	*ctx;
 	struct net_device	*dev;
@@ -11,6 +18,9 @@ struct io_zc_rx_ifq {
 	u32			rq_entries, cq_entries;
 	void			*pool;
 
+	unsigned		nr_sockets;
+	struct file		*sockets[IO_ZC_MAX_IFQ_SOCKETS];
+
 	/* hw rx descriptor ring id */
 	u32			if_rxq_id;
 };
@@ -19,6 +29,8 @@ struct io_zc_rx_ifq {
 int io_register_zc_rx_ifq(struct io_ring_ctx *ctx,
 			  struct io_uring_zc_rx_ifq_reg __user *arg);
 int io_unregister_zc_rx_ifq(struct io_ring_ctx *ctx);
+int io_register_zc_rx_sock(struct io_ring_ctx *ctx,
+			   struct io_uring_zc_rx_sock_reg __user *arg);
 #else
 static inline int io_register_zc_rx_ifq(struct io_ring_ctx *ctx,
 			  struct io_uring_zc_rx_ifq_reg __user *arg)
@@ -29,6 +41,11 @@ static inline int io_unregister_zc_rx_ifq(struct io_ring_ctx *ctx)
 {
 	return -EOPNOTSUPP;
 }
+static inline int io_register_zc_rx_sock(struct io_ring_ctx *ctx,
+				struct io_uring_zc_rx_sock_reg __user *arg)
+{
+	return -EOPNOTSUPP;
+}
 #endif
 
 #endif
diff --git a/net/socket.c b/net/socket.c
index c4a6f5532955..419b7bda3f9c 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -637,6 +637,7 @@ struct socket *sock_alloc(void)
 
 	sock = SOCKET_I(inode);
 
+	sock->zc_rx_idx = 0;
 	inode->i_ino = get_next_ino();
 	inode->i_mode = S_IFSOCK | S_IRWXUGO;
 	inode->i_uid = current_fsuid();
-- 
2.39.3