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-rw-r--r--io_uring/msg_ring.c298
1 files changed, 298 insertions, 0 deletions
diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c
new file mode 100644
index 0000000000..cd6dcf634b
--- /dev/null
+++ b/io_uring/msg_ring.c
@@ -0,0 +1,298 @@
+// 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"
+
+
+/* All valid masks for MSG_RING */
+#define IORING_MSG_RING_MASK (IORING_MSG_RING_CQE_SKIP | \
+ IORING_MSG_RING_FLAGS_PASS)
+
+struct io_msg {
+ struct file *file;
+ struct file *src_file;
+ struct callback_head tw;
+ u64 user_data;
+ u32 len;
+ u32 cmd;
+ u32 src_fd;
+ union {
+ u32 dst_fd;
+ u32 cqe_flags;
+ };
+ u32 flags;
+};
+
+static void io_double_unlock_ctx(struct io_ring_ctx *octx)
+{
+ 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;
+}
+
+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 inline bool io_msg_need_remote(struct io_ring_ctx *target_ctx)
+{
+ if (!target_ctx->task_complete)
+ return false;
+ return current != target_ctx->submitter_task;
+}
+
+static int io_msg_exec_remote(struct io_kiocb *req, task_work_func_t func)
+{
+ struct io_ring_ctx *ctx = req->file->private_data;
+ struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
+ struct task_struct *task = READ_ONCE(ctx->submitter_task);
+
+ if (unlikely(!task))
+ return -EOWNERDEAD;
+
+ init_task_work(&msg->tw, func);
+ if (task_work_add(ctx->submitter_task, &msg->tw, TWA_SIGNAL))
+ return -EOWNERDEAD;
+
+ return IOU_ISSUE_SKIP_COMPLETE;
+}
+
+static void io_msg_tw_complete(struct callback_head *head)
+{
+ struct io_msg *msg = container_of(head, struct io_msg, tw);
+ struct io_kiocb *req = cmd_to_io_kiocb(msg);
+ struct io_ring_ctx *target_ctx = req->file->private_data;
+ int ret = 0;
+
+ if (current->flags & PF_EXITING) {
+ ret = -EOWNERDEAD;
+ } else {
+ u32 flags = 0;
+
+ if (msg->flags & IORING_MSG_RING_FLAGS_PASS)
+ flags = msg->cqe_flags;
+
+ /*
+ * If the target ring is using IOPOLL mode, then we need to be
+ * holding the uring_lock for posting completions. Other ring
+ * types rely on the regular completion locking, which is
+ * handled while posting.
+ */
+ if (target_ctx->flags & IORING_SETUP_IOPOLL)
+ mutex_lock(&target_ctx->uring_lock);
+ if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
+ ret = -EOVERFLOW;
+ if (target_ctx->flags & IORING_SETUP_IOPOLL)
+ mutex_unlock(&target_ctx->uring_lock);
+ }
+
+ if (ret < 0)
+ req_set_fail(req);
+ io_req_queue_tw_complete(req, ret);
+}
+
+static int io_msg_ring_data(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);
+ u32 flags = 0;
+ int ret;
+
+ if (msg->src_fd || msg->flags & ~IORING_MSG_RING_FLAGS_PASS)
+ return -EINVAL;
+ if (!(msg->flags & IORING_MSG_RING_FLAGS_PASS) && msg->dst_fd)
+ return -EINVAL;
+ if (target_ctx->flags & IORING_SETUP_R_DISABLED)
+ return -EBADFD;
+
+ if (io_msg_need_remote(target_ctx))
+ return io_msg_exec_remote(req, io_msg_tw_complete);
+
+ if (msg->flags & IORING_MSG_RING_FLAGS_PASS)
+ flags = msg->cqe_flags;
+
+ ret = -EOVERFLOW;
+ if (target_ctx->flags & IORING_SETUP_IOPOLL) {
+ if (unlikely(io_double_lock_ctx(target_ctx, issue_flags)))
+ return -EAGAIN;
+ if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
+ ret = 0;
+ io_double_unlock_ctx(target_ctx);
+ } else {
+ if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, flags))
+ ret = 0;
+ }
+ return ret;
+}
+
+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;
+ 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 = io_file_from_index(&ctx->file_table, idx);
+ 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, ret, 0))
+ ret = -EOVERFLOW;
+out_unlock:
+ io_double_unlock_ctx(target_ctx);
+ return ret;
+}
+
+static void io_msg_tw_fd_complete(struct callback_head *head)
+{
+ struct io_msg *msg = container_of(head, struct io_msg, tw);
+ struct io_kiocb *req = cmd_to_io_kiocb(msg);
+ int ret = -EOWNERDEAD;
+
+ if (!(current->flags & PF_EXITING))
+ ret = io_msg_install_complete(req, IO_URING_F_UNLOCKED);
+ if (ret < 0)
+ req_set_fail(req);
+ io_req_queue_tw_complete(req, 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 (msg->len)
+ return -EINVAL;
+ if (target_ctx == ctx)
+ return -EINVAL;
+ if (target_ctx->flags & IORING_SETUP_R_DISABLED)
+ return -EBADFD;
+ 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;
+ }
+
+ if (io_msg_need_remote(target_ctx))
+ return io_msg_exec_remote(req, io_msg_tw_fd_complete);
+ 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_MASK)
+ 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, issue_flags);
+ break;
+ case IORING_MSG_SEND_FD:
+ ret = io_msg_send_fd(req, issue_flags);
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+done:
+ if (ret < 0) {
+ if (ret == -EAGAIN || ret == IOU_ISSUE_SKIP_COMPLETE)
+ return ret;
+ req_set_fail(req);
+ }
+ io_req_set_res(req, ret, 0);
+ return IOU_OK;
+}