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// 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;
u64 user_data;
u32 len;
u32 cmd;
u32 src_fd;
u32 dst_fd;
u32 flags;
};
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 (target_ctx->flags & IORING_SETUP_R_DISABLED)
return -EBADFD;
if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0, true))
return 0;
return -EOVERFLOW;
}
static void io_double_unlock_ctx(struct io_ring_ctx *ctx,
struct io_ring_ctx *octx,
unsigned int issue_flags)
{
if (issue_flags & IO_URING_F_UNLOCKED)
mutex_unlock(&ctx->uring_lock);
mutex_unlock(&octx->uring_lock);
}
static int io_double_lock_ctx(struct io_ring_ctx *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;
}
/* Always grab smallest value ctx first. We know ctx != octx. */
if (ctx < octx) {
mutex_lock(&ctx->uring_lock);
mutex_lock(&octx->uring_lock);
} else {
mutex_lock(&octx->uring_lock);
mutex_lock(&ctx->uring_lock);
}
return 0;
}
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;
unsigned long file_ptr;
struct file *src_file;
int ret;
if (target_ctx == ctx)
return -EINVAL;
if (target_ctx->flags & IORING_SETUP_R_DISABLED)
return -EBADFD;
ret = io_double_lock_ctx(ctx, target_ctx, issue_flags);
if (unlikely(ret))
return ret;
ret = -EBADF;
if (unlikely(msg->src_fd >= ctx->nr_user_files))
goto out_unlock;
msg->src_fd = array_index_nospec(msg->src_fd, ctx->nr_user_files);
file_ptr = io_fixed_file_slot(&ctx->file_table, msg->src_fd)->file_ptr;
if (!file_ptr)
goto out_unlock;
src_file = (struct file *) (file_ptr & FFS_MASK);
get_file(src_file);
ret = __io_fixed_fd_install(target_ctx, src_file, msg->dst_fd);
if (ret < 0) {
fput(src_file);
goto out_unlock;
}
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, true))
ret = -EOVERFLOW;
out_unlock:
io_double_unlock_ctx(ctx, target_ctx, issue_flags);
return ret;
}
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->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;
}
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