io_uring: add support for passing fixed file descriptors

[linux-2.6-microblaze.git] / io_uring / msg_ring.c

diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c
index b02be23..939205b 100644 (file)
--- a/io_uring/msg_ring.c
+++ b/io_uring/msg_ring.c
@@ -3,46 +3,162 @@
 #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);
+
+       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 *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_ring_ctx *ctx = req->ctx;
+       unsigned long file_ptr;
+       struct file *src_file;
+       int ret;
+
+       if (target_ctx == ctx)
+               return -EINVAL;
+
+       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;
+       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))
+               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);
 
-       if (unlikely(sqe->addr || sqe->rw_flags || sqe->splice_fd_in ||
-                    sqe->buf_index || sqe->personality))
+       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_ring_ctx *target_ctx;
        int ret;
 
        ret = -EBADFD;
        if (!io_is_uring_fops(req->file))
                goto done;
 
-       ret = -EOVERFLOW;
-       target_ctx = req->file->private_data;
-       if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0))
-               ret = 0;
+       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 < 0)