299 lines
7.5 KiB
C
299 lines
7.5 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/file.h>
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#include <linux/slab.h>
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#include <linux/nospec.h>
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#include <linux/io_uring.h>
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#include <uapi/linux/io_uring.h>
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#include "io_uring.h"
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#include "rsrc.h"
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#include "filetable.h"
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#include "msg_ring.h"
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/* All valid masks for MSG_RING */
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#define IORING_MSG_RING_MASK (IORING_MSG_RING_CQE_SKIP | \
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IORING_MSG_RING_FLAGS_PASS)
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struct io_msg {
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struct file *file;
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struct file *src_file;
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struct callback_head tw;
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u64 user_data;
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u32 len;
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u32 cmd;
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u32 src_fd;
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union {
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u32 dst_fd;
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u32 cqe_flags;
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};
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u32 flags;
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};
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static void io_double_unlock_ctx(struct io_ring_ctx *octx)
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{
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mutex_unlock(&octx->uring_lock);
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}
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static int io_double_lock_ctx(struct io_ring_ctx *octx,
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unsigned int issue_flags)
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{
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/*
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* To ensure proper ordering between the two ctxs, we can only
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* attempt a trylock on the target. If that fails and we already have
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* the source ctx lock, punt to io-wq.
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*/
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if (!(issue_flags & IO_URING_F_UNLOCKED)) {
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if (!mutex_trylock(&octx->uring_lock))
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return -EAGAIN;
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return 0;
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}
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mutex_lock(&octx->uring_lock);
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return 0;
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}
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void io_msg_ring_cleanup(struct io_kiocb *req)
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{
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struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
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if (WARN_ON_ONCE(!msg->src_file))
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return;
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fput(msg->src_file);
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msg->src_file = NULL;
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}
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static inline bool io_msg_need_remote(struct io_ring_ctx *target_ctx)
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{
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if (!target_ctx->task_complete)
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return false;
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return current != target_ctx->submitter_task;
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}
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static int io_msg_exec_remote(struct io_kiocb *req, task_work_func_t func)
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{
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struct io_ring_ctx *ctx = req->file->private_data;
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struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
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struct task_struct *task = READ_ONCE(ctx->submitter_task);
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if (unlikely(!task))
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return -EOWNERDEAD;
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init_task_work(&msg->tw, func);
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if (task_work_add(ctx->submitter_task, &msg->tw, TWA_SIGNAL))
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return -EOWNERDEAD;
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return IOU_ISSUE_SKIP_COMPLETE;
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}
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static void io_msg_tw_complete(struct callback_head *head)
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{
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struct io_msg *msg = container_of(head, struct io_msg, tw);
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struct io_kiocb *req = cmd_to_io_kiocb(msg);
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struct io_ring_ctx *target_ctx = req->file->private_data;
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int ret = 0;
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if (current->flags & PF_EXITING) {
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ret = -EOWNERDEAD;
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} else {
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u32 flags = 0;
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if (msg->flags & IORING_MSG_RING_FLAGS_PASS)
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flags = msg->cqe_flags;
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/*
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* If the target ring is using IOPOLL mode, then we need to be
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* holding the uring_lock for posting completions. Other ring
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* types rely on the regular completion locking, which is
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* handled while posting.
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*/
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if (target_ctx->flags & IORING_SETUP_IOPOLL)
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mutex_lock(&target_ctx->uring_lock);
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if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
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ret = -EOVERFLOW;
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if (target_ctx->flags & IORING_SETUP_IOPOLL)
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mutex_unlock(&target_ctx->uring_lock);
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}
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if (ret < 0)
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req_set_fail(req);
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io_req_queue_tw_complete(req, ret);
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}
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static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags)
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{
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struct io_ring_ctx *target_ctx = req->file->private_data;
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struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
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u32 flags = 0;
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int ret;
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if (msg->src_fd || msg->flags & ~IORING_MSG_RING_FLAGS_PASS)
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return -EINVAL;
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if (!(msg->flags & IORING_MSG_RING_FLAGS_PASS) && msg->dst_fd)
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return -EINVAL;
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if (target_ctx->flags & IORING_SETUP_R_DISABLED)
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return -EBADFD;
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if (io_msg_need_remote(target_ctx))
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return io_msg_exec_remote(req, io_msg_tw_complete);
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if (msg->flags & IORING_MSG_RING_FLAGS_PASS)
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flags = msg->cqe_flags;
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ret = -EOVERFLOW;
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if (target_ctx->flags & IORING_SETUP_IOPOLL) {
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if (unlikely(io_double_lock_ctx(target_ctx, issue_flags)))
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return -EAGAIN;
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if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
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ret = 0;
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io_double_unlock_ctx(target_ctx);
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} else {
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if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
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ret = 0;
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}
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return ret;
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}
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static struct file *io_msg_grab_file(struct io_kiocb *req, unsigned int issue_flags)
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{
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struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
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struct io_ring_ctx *ctx = req->ctx;
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struct file *file = NULL;
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int idx = msg->src_fd;
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io_ring_submit_lock(ctx, issue_flags);
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if (likely(idx < ctx->nr_user_files)) {
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idx = array_index_nospec(idx, ctx->nr_user_files);
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file = io_file_from_index(&ctx->file_table, idx);
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if (file)
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get_file(file);
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}
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io_ring_submit_unlock(ctx, issue_flags);
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return file;
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}
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static int io_msg_install_complete(struct io_kiocb *req, unsigned int issue_flags)
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{
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struct io_ring_ctx *target_ctx = req->file->private_data;
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struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
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struct file *src_file = msg->src_file;
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int ret;
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if (unlikely(io_double_lock_ctx(target_ctx, issue_flags)))
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return -EAGAIN;
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ret = __io_fixed_fd_install(target_ctx, src_file, msg->dst_fd);
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if (ret < 0)
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goto out_unlock;
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msg->src_file = NULL;
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req->flags &= ~REQ_F_NEED_CLEANUP;
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if (msg->flags & IORING_MSG_RING_CQE_SKIP)
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goto out_unlock;
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/*
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* If this fails, the target still received the file descriptor but
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* wasn't notified of the fact. This means that if this request
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* completes with -EOVERFLOW, then the sender must ensure that a
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* later IORING_OP_MSG_RING delivers the message.
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*/
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if (!io_post_aux_cqe(target_ctx, msg->user_data, ret, 0))
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ret = -EOVERFLOW;
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out_unlock:
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io_double_unlock_ctx(target_ctx);
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return ret;
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}
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static void io_msg_tw_fd_complete(struct callback_head *head)
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{
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struct io_msg *msg = container_of(head, struct io_msg, tw);
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struct io_kiocb *req = cmd_to_io_kiocb(msg);
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int ret = -EOWNERDEAD;
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if (!(current->flags & PF_EXITING))
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ret = io_msg_install_complete(req, IO_URING_F_UNLOCKED);
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if (ret < 0)
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req_set_fail(req);
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io_req_queue_tw_complete(req, ret);
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}
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static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags)
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{
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struct io_ring_ctx *target_ctx = req->file->private_data;
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struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
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struct io_ring_ctx *ctx = req->ctx;
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struct file *src_file = msg->src_file;
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if (msg->len)
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return -EINVAL;
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if (target_ctx == ctx)
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return -EINVAL;
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if (target_ctx->flags & IORING_SETUP_R_DISABLED)
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return -EBADFD;
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if (!src_file) {
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src_file = io_msg_grab_file(req, issue_flags);
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if (!src_file)
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return -EBADF;
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msg->src_file = src_file;
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req->flags |= REQ_F_NEED_CLEANUP;
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}
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if (io_msg_need_remote(target_ctx))
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return io_msg_exec_remote(req, io_msg_tw_fd_complete);
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return io_msg_install_complete(req, issue_flags);
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}
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int io_msg_ring_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
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{
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struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
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if (unlikely(sqe->buf_index || sqe->personality))
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return -EINVAL;
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msg->src_file = NULL;
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msg->user_data = READ_ONCE(sqe->off);
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msg->len = READ_ONCE(sqe->len);
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msg->cmd = READ_ONCE(sqe->addr);
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msg->src_fd = READ_ONCE(sqe->addr3);
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msg->dst_fd = READ_ONCE(sqe->file_index);
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msg->flags = READ_ONCE(sqe->msg_ring_flags);
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if (msg->flags & ~IORING_MSG_RING_MASK)
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return -EINVAL;
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return 0;
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}
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int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags)
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{
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struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
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int ret;
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ret = -EBADFD;
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if (!io_is_uring_fops(req->file))
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goto done;
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switch (msg->cmd) {
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case IORING_MSG_DATA:
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ret = io_msg_ring_data(req, issue_flags);
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break;
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case IORING_MSG_SEND_FD:
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ret = io_msg_send_fd(req, issue_flags);
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break;
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default:
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ret = -EINVAL;
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break;
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}
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done:
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if (ret < 0) {
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if (ret == -EAGAIN || ret == IOU_ISSUE_SKIP_COMPLETE)
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return ret;
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req_set_fail(req);
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}
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io_req_set_res(req, ret, 0);
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return IOU_OK;
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}
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