OvmfPkg/VirtioFsDxe/FuseOpenOrCreate.c

   1 /** @file
   2   FUSE_CREATE wrapper for the Virtio Filesystem device.
   3
   4   Copyright (C) 2020, Red Hat, Inc.
   5
   6   SPDX-License-Identifier: BSD-2-Clause-Patent
   7 **/
   8
   9 #include <Library/BaseLib.h> // AsciiStrSize()
  10
  11 #include "VirtioFsDxe.h"
  12
  13 /**
  14   Send a FUSE_CREATE request to the Virtio Filesystem device, for opening a
  15   regular file with (O_RDWR | O_CREAT) semantics.
  16
  17   The function may only be called after VirtioFsFuseInitSession() returns
  18   successfully and before VirtioFsUninit() is called.
  19
  20   @param[in,out] VirtioFs  The Virtio Filesystem device to send the FUSE_CREATE
  21                            request to. On output, the FUSE request counter
  22                            "VirtioFs->RequestId" will have been incremented.
  23
  24   @param[in] ParentNodeId  The inode number of the direct parent directory of
  25                            the regular file to open or create.
  26
  27   @param[in] Name          The single-component filename of the regular file to
  28                            open or create, under the parent directory
  29                            identified by ParentNodeId.
  30
  31   @param[out] NodeId       The inode number of the regular file, returned by
  32                            the Virtio Filesystem device.
  33
  34   @param[out] FuseHandle   The open file handle returned by the Virtio
  35                            Filesystem device.
  36
  37   @retval EFI_SUCCESS  The regular file has been opened, and (if necessary)
  38                        created.
  39
  40   @return              The "errno" value mapped to an EFI_STATUS code, if the
  41                        Virtio Filesystem device explicitly reported an error.
  42
  43   @return              Error codes propagated from VirtioFsSgListsValidate(),
  44                        VirtioFsFuseNewRequest(), VirtioFsSgListsSubmit(),
  45                        VirtioFsFuseCheckResponse().
  46 **/
  47 EFI_STATUS
  48 VirtioFsFuseOpenOrCreate (
  49   IN OUT VIRTIO_FS  *VirtioFs,
  50   IN     UINT64     ParentNodeId,
  51   IN     CHAR8      *Name,
  52   OUT UINT64        *NodeId,
  53   OUT UINT64        *FuseHandle
  54   )
  55 {
  56   VIRTIO_FS_FUSE_REQUEST              CommonReq;
  57   VIRTIO_FS_FUSE_CREATE_REQUEST       CreateReq;
  58   VIRTIO_FS_IO_VECTOR                 ReqIoVec[3];
  59   VIRTIO_FS_SCATTER_GATHER_LIST       ReqSgList;
  60   VIRTIO_FS_FUSE_RESPONSE             CommonResp;
  61   VIRTIO_FS_FUSE_NODE_RESPONSE        NodeResp;
  62   VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE  AttrResp;
  63   VIRTIO_FS_FUSE_OPEN_RESPONSE        OpenResp;
  64   VIRTIO_FS_IO_VECTOR                 RespIoVec[4];
  65   VIRTIO_FS_SCATTER_GATHER_LIST       RespSgList;
  66   EFI_STATUS                          Status;
  67
  68   //
  69   // Set up the scatter-gather lists.
  70   //
  71   ReqIoVec[0].Buffer = &CommonReq;
  72   ReqIoVec[0].Size   = sizeof CommonReq;
  73   ReqIoVec[1].Buffer = &CreateReq;
  74   ReqIoVec[1].Size   = sizeof CreateReq;
  75   ReqIoVec[2].Buffer = Name;
  76   ReqIoVec[2].Size   = AsciiStrSize (Name);
  77   ReqSgList.IoVec    = ReqIoVec;
  78   ReqSgList.NumVec   = ARRAY_SIZE (ReqIoVec);
  79
  80   RespIoVec[0].Buffer = &CommonResp;
  81   RespIoVec[0].Size   = sizeof CommonResp;
  82   RespIoVec[1].Buffer = &NodeResp;
  83   RespIoVec[1].Size   = sizeof NodeResp;
  84   RespIoVec[2].Buffer = &AttrResp;
  85   RespIoVec[2].Size   = sizeof AttrResp;
  86   RespIoVec[3].Buffer = &OpenResp;
  87   RespIoVec[3].Size   = sizeof OpenResp;
  88   RespSgList.IoVec    = RespIoVec;
  89   RespSgList.NumVec   = ARRAY_SIZE (RespIoVec);
  90
  91   //
  92   // Validate the scatter-gather lists; calculate the total transfer sizes.
  93   //
  94   Status = VirtioFsSgListsValidate (VirtioFs, &ReqSgList, &RespSgList);
  95   if (EFI_ERROR (Status)) {
  96     return Status;
  97   }
  98
  99   //
 100   // Populate the common request header.
 101   //
 102   Status = VirtioFsFuseNewRequest (
 103              VirtioFs,
 104              &CommonReq,
 105              ReqSgList.TotalSize,
 106              VirtioFsFuseOpCreate,
 107              ParentNodeId
 108              );
 109   if (EFI_ERROR (Status)) {
 110     return Status;
 111   }
 112
 113   //
 114   // Populate the FUSE_CREATE-specific fields.
 115   //
 116   // VIRTIO_FS_FUSE_OPEN_REQ_F_RDWR is why this request can never open a
 117   // directory (EISDIR). And VIRTIO_FS_FUSE_OPEN_REQ_F_RDWR is consistent with
 118   // the only OpenMode of EFI_FILE_PROTOCOL.Open() that enables filesystem
 119   // object creation -- that is, Create/Read/Write.
 120   //
 121   CreateReq.Flags = VIRTIO_FS_FUSE_OPEN_REQ_F_RDWR;
 122   CreateReq.Mode  = (VIRTIO_FS_FUSE_MODE_PERM_RUSR |
 123                      VIRTIO_FS_FUSE_MODE_PERM_WUSR |
 124                      VIRTIO_FS_FUSE_MODE_PERM_RGRP |
 125                      VIRTIO_FS_FUSE_MODE_PERM_WGRP |
 126                      VIRTIO_FS_FUSE_MODE_PERM_ROTH |
 127                      VIRTIO_FS_FUSE_MODE_PERM_WOTH);
 128   CreateReq.Umask   = 0;
 129   CreateReq.Padding = 0;
 130
 131   //
 132   // Submit the request.
 133   //
 134   Status = VirtioFsSgListsSubmit (VirtioFs, &ReqSgList, &RespSgList);
 135   if (EFI_ERROR (Status)) {
 136     return Status;
 137   }
 138
 139   //
 140   // Verify the response (all response buffers are fixed size).
 141   //
 142   Status = VirtioFsFuseCheckResponse (&RespSgList, CommonReq.Unique, NULL);
 143   if (EFI_ERROR (Status)) {
 144     if (Status == EFI_DEVICE_ERROR) {
 145       DEBUG ((
 146         DEBUG_ERROR,
 147         "%a: Label=\"%s\" ParentNodeId=%Lu Name=\"%a\" "
 148         "Errno=%d\n",
 149         __FUNCTION__,
 150         VirtioFs->Label,
 151         ParentNodeId,
 152         Name,
 153         CommonResp.Error
 154         ));
 155       Status = VirtioFsErrnoToEfiStatus (CommonResp.Error);
 156     }
 157
 158     return Status;
 159   }
 160
 161   //
 162   // Output the NodeId of the (possibly new) regular file. Also output the open
 163   // file handle.
 164   //
 165   *NodeId     = NodeResp.NodeId;
 166   *FuseHandle = OpenResp.FileHandle;
 167   return EFI_SUCCESS;
 168 }