[linux-block.git] / io_uring / msg_ring.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/nospec.h>
#include <linux/io_uring.h>

#include <uapi/linux/io_uring.h>

#include "io_uring.h"
#include "rsrc.h"
#include "filetable.h"
#include "msg_ring.h"

struct io_msg {
	struct file			*file;
	struct file			*src_file;
	u64 user_data;
	u32 len;
	u32 cmd;
	u32 src_fd;
	u32 dst_fd;
	u32 flags;
};

void io_msg_ring_cleanup(struct io_kiocb *req)
{
	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);

	if (WARN_ON_ONCE(!msg->src_file))
		return;

	fput(msg->src_file);
	msg->src_file = NULL;
}

static int io_msg_ring_data(struct io_kiocb *req)
{
	struct io_ring_ctx *target_ctx = req->file->private_data;
	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);

	if (msg->src_fd || msg->dst_fd || msg->flags)
		return -EINVAL;

	if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0))
		return 0;

	return -EOVERFLOW;
}

static void io_double_unlock_ctx(struct io_ring_ctx *octx,
				 unsigned int issue_flags)
{
	mutex_unlock(&octx->uring_lock);
}

static int io_double_lock_ctx(struct io_ring_ctx *octx,
			      unsigned int issue_flags)
{
	/*
	 * To ensure proper ordering between the two ctxs, we can only
	 * attempt a trylock on the target. If that fails and we already have
	 * the source ctx lock, punt to io-wq.
	 */
	if (!(issue_flags & IO_URING_F_UNLOCKED)) {
		if (!mutex_trylock(&octx->uring_lock))
			return -EAGAIN;
		return 0;
	}
	mutex_lock(&octx->uring_lock);
	return 0;
}

static struct file *io_msg_grab_file(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
	struct io_ring_ctx *ctx = req->ctx;
	struct file *file = NULL;
	unsigned long file_ptr;
	int idx = msg->src_fd;

	io_ring_submit_lock(ctx, issue_flags);
	if (likely(idx < ctx->nr_user_files)) {
		idx = array_index_nospec(idx, ctx->nr_user_files);
		file_ptr = io_fixed_file_slot(&ctx->file_table, idx)->file_ptr;
		file = (struct file *) (file_ptr & FFS_MASK);
		if (file)
			get_file(file);
	}
	io_ring_submit_unlock(ctx, issue_flags);
	return file;
}

static int io_msg_install_complete(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_ring_ctx *target_ctx = req->file->private_data;
	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
	struct file *src_file = msg->src_file;
	int ret;

	if (unlikely(io_double_lock_ctx(target_ctx, issue_flags)))
		return -EAGAIN;

	ret = __io_fixed_fd_install(target_ctx, src_file, msg->dst_fd);
	if (ret < 0)
		goto out_unlock;

	msg->src_file = NULL;
	req->flags &= ~REQ_F_NEED_CLEANUP;

	if (msg->flags & IORING_MSG_RING_CQE_SKIP)
		goto out_unlock;
	/*
	 * If this fails, the target still received the file descriptor but
	 * wasn't notified of the fact. This means that if this request
	 * completes with -EOVERFLOW, then the sender must ensure that a
	 * later IORING_OP_MSG_RING delivers the message.
	 */
	if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0))
		ret = -EOVERFLOW;
out_unlock:
	io_double_unlock_ctx(target_ctx, issue_flags);
	return ret;
}

static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_ring_ctx *target_ctx = req->file->private_data;
	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
	struct io_ring_ctx *ctx = req->ctx;
	struct file *src_file = msg->src_file;

	if (target_ctx == ctx)
		return -EINVAL;
	if (!src_file) {
		src_file = io_msg_grab_file(req, issue_flags);
		if (!src_file)
			return -EBADF;
		msg->src_file = src_file;
		req->flags |= REQ_F_NEED_CLEANUP;
	}
	return io_msg_install_complete(req, issue_flags);
}

int io_msg_ring_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);

	if (unlikely(sqe->buf_index || sqe->personality))
		return -EINVAL;

	msg->src_file = NULL;
	msg->user_data = READ_ONCE(sqe->off);
	msg->len = READ_ONCE(sqe->len);
	msg->cmd = READ_ONCE(sqe->addr);
	msg->src_fd = READ_ONCE(sqe->addr3);
	msg->dst_fd = READ_ONCE(sqe->file_index);
	msg->flags = READ_ONCE(sqe->msg_ring_flags);
	if (msg->flags & ~IORING_MSG_RING_CQE_SKIP)
		return -EINVAL;

	return 0;
}

int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags)
{
	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
	int ret;

	ret = -EBADFD;
	if (!io_is_uring_fops(req->file))
		goto done;

	switch (msg->cmd) {
	case IORING_MSG_DATA:
		ret = io_msg_ring_data(req);
		break;
	case IORING_MSG_SEND_FD:
		ret = io_msg_send_fd(req, issue_flags);
		break;
	default:
		ret = -EINVAL;
		break;
	}

done:
	if (ret == -EAGAIN)
		return -EAGAIN;
	if (ret < 0)
		req_set_fail(req);
	io_req_set_res(req, ret, 0);
	return IOU_OK;
}
Commit	Line	Data
36404b09 JA	1	// SPDX-License-Identifier: GPL-2.0
	2	#include <linux/kernel.h>
	3	#include <linux/errno.h>
	4	#include <linux/file.h>
	5	#include <linux/slab.h>
e6130eba	6	#include <linux/nospec.h>
36404b09 JA	7	#include <linux/io_uring.h>
	8
	9	#include <uapi/linux/io_uring.h>
	10
36404b09	11	#include "io_uring.h"
e6130eba JA	12	#include "rsrc.h"
e6130eba JA	13	#include "filetable.h"
36404b09 JA	14	#include "msg_ring.h"
	15
	16	struct io_msg {
	17	struct file *file;
11373026	18	struct file *src_file;
36404b09 JA	19	u64 user_data;
36404b09 JA	20	u32 len;
e6130eba JA	21	u32 cmd;
	22	u32 src_fd;
	23	u32 dst_fd;
	24	u32 flags;
36404b09 JA	25	};
36404b09 JA	26
11373026 PB	27	void io_msg_ring_cleanup(struct io_kiocb *req)
	28	{
	29	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
	30
	31	if (WARN_ON_ONCE(!msg->src_file))
	32	return;
	33
	34	fput(msg->src_file);
	35	msg->src_file = NULL;
	36	}
	37
e6130eba JA	38	static int io_msg_ring_data(struct io_kiocb *req)
	39	{
	40	struct io_ring_ctx *target_ctx = req->file->private_data;
f2ccb5ae	41	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
e6130eba JA	42
	43	if (msg->src_fd \|\| msg->dst_fd \|\| msg->flags)
	44	return -EINVAL;
	45
b529c96a	46	if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0))
e6130eba JA	47	return 0;
	48
	49	return -EOVERFLOW;
	50	}
	51
11373026	52	static void io_double_unlock_ctx(struct io_ring_ctx *octx,
e6130eba JA	53	unsigned int issue_flags)
e6130eba JA	54	{
e6130eba JA	55	mutex_unlock(&octx->uring_lock);
	56	}
	57
11373026	58	static int io_double_lock_ctx(struct io_ring_ctx *octx,
e6130eba JA	59	unsigned int issue_flags)
	60	{
	61	/*
	62	* To ensure proper ordering between the two ctxs, we can only
	63	* attempt a trylock on the target. If that fails and we already have
	64	* the source ctx lock, punt to io-wq.
	65	*/
	66	if (!(issue_flags & IO_URING_F_UNLOCKED)) {
	67	if (!mutex_trylock(&octx->uring_lock))
	68	return -EAGAIN;
	69	return 0;
	70	}
11373026 PB	71	mutex_lock(&octx->uring_lock);
	72	return 0;
	73	}
e6130eba	74
11373026 PB	75	static struct file io_msg_grab_file(struct io_kiocb req, unsigned int issue_flags)
	76	{
	77	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
	78	struct io_ring_ctx *ctx = req->ctx;
	79	struct file *file = NULL;
	80	unsigned long file_ptr;
	81	int idx = msg->src_fd;
	82
	83	io_ring_submit_lock(ctx, issue_flags);
	84	if (likely(idx < ctx->nr_user_files)) {
	85	idx = array_index_nospec(idx, ctx->nr_user_files);
	86	file_ptr = io_fixed_file_slot(&ctx->file_table, idx)->file_ptr;
	87	file = (struct file *) (file_ptr & FFS_MASK);
	88	if (file)
	89	get_file(file);
e6130eba	90	}
11373026 PB	91	io_ring_submit_unlock(ctx, issue_flags);
11373026 PB	92	return file;
e6130eba JA	93	}
e6130eba JA	94
17211310	95	static int io_msg_install_complete(struct io_kiocb *req, unsigned int issue_flags)
e6130eba JA	96	{
e6130eba JA	97	struct io_ring_ctx *target_ctx = req->file->private_data;
f2ccb5ae	98	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
11373026	99	struct file *src_file = msg->src_file;
e6130eba JA	100	int ret;
e6130eba JA	101
11373026 PB	102	if (unlikely(io_double_lock_ctx(target_ctx, issue_flags)))
11373026 PB	103	return -EAGAIN;
e6130eba JA	104
e6130eba JA	105	ret = __io_fixed_fd_install(target_ctx, src_file, msg->dst_fd);
11373026	106	if (ret < 0)
e6130eba	107	goto out_unlock;
17211310	108
11373026 PB	109	msg->src_file = NULL;
11373026 PB	110	req->flags &= ~REQ_F_NEED_CLEANUP;
e6130eba JA	111
	112	if (msg->flags & IORING_MSG_RING_CQE_SKIP)
	113	goto out_unlock;
e6130eba JA	114	/*
	115	* If this fails, the target still received the file descriptor but
	116	* wasn't notified of the fact. This means that if this request
	117	* completes with -EOVERFLOW, then the sender must ensure that a
	118	* later IORING_OP_MSG_RING delivers the message.
	119	*/
b529c96a	120	if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0))
e6130eba JA	121	ret = -EOVERFLOW;
e6130eba JA	122	out_unlock:
11373026	123	io_double_unlock_ctx(target_ctx, issue_flags);
e6130eba JA	124	return ret;
	125	}
	126
17211310 PB	127	static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags)
	128	{
	129	struct io_ring_ctx *target_ctx = req->file->private_data;
	130	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
	131	struct io_ring_ctx *ctx = req->ctx;
	132	struct file *src_file = msg->src_file;
	133
	134	if (target_ctx == ctx)
	135	return -EINVAL;
	136	if (!src_file) {
	137	src_file = io_msg_grab_file(req, issue_flags);
	138	if (!src_file)
	139	return -EBADF;
	140	msg->src_file = src_file;
	141	req->flags \|= REQ_F_NEED_CLEANUP;
	142	}
	143	return io_msg_install_complete(req, issue_flags);
	144	}
	145
36404b09 JA	146	int io_msg_ring_prep(struct io_kiocb req, const struct io_uring_sqe sqe)
36404b09 JA	147	{
f2ccb5ae	148	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
36404b09	149
e6130eba	150	if (unlikely(sqe->buf_index \|\| sqe->personality))
36404b09 JA	151	return -EINVAL;
36404b09 JA	152
11373026	153	msg->src_file = NULL;
36404b09 JA	154	msg->user_data = READ_ONCE(sqe->off);
36404b09 JA	155	msg->len = READ_ONCE(sqe->len);
e6130eba JA	156	msg->cmd = READ_ONCE(sqe->addr);
	157	msg->src_fd = READ_ONCE(sqe->addr3);
	158	msg->dst_fd = READ_ONCE(sqe->file_index);
	159	msg->flags = READ_ONCE(sqe->msg_ring_flags);
	160	if (msg->flags & ~IORING_MSG_RING_CQE_SKIP)
	161	return -EINVAL;
	162
36404b09 JA	163	return 0;
	164	}
	165
	166	int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags)
	167	{
f2ccb5ae	168	struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
36404b09 JA	169	int ret;
	170
	171	ret = -EBADFD;
	172	if (!io_is_uring_fops(req->file))
	173	goto done;
	174
e6130eba JA	175	switch (msg->cmd) {
	176	case IORING_MSG_DATA:
	177	ret = io_msg_ring_data(req);
	178	break;
	179	case IORING_MSG_SEND_FD:
	180	ret = io_msg_send_fd(req, issue_flags);
	181	break;
	182	default:
	183	ret = -EINVAL;
	184	break;
	185	}
36404b09 JA	186
36404b09 JA	187	done:
4c979eae PB	188	if (ret == -EAGAIN)
4c979eae PB	189	return -EAGAIN;
36404b09 JA	190	if (ret < 0)
	191	req_set_fail(req);
	192	io_req_set_res(req, ret, 0);
36404b09 JA	193	return IOU_OK;
36404b09 JA	194	}