OvmfPkg/VirtioFsDxe/FuseLookup.c

   1 /** @file
   2   FUSE_LOOKUP 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_LOOKUP request to the Virtio Filesystem device, for resolving a
  15   filename to an inode.
  16
  17   The function returns EFI_NOT_FOUND exclusively if the Virtio Filesystem
  18   device explicitly responds with ENOENT -- "No such file or directory".
  19
  20   The function may only be called after VirtioFsFuseInitSession() returns
  21   successfully and before VirtioFsUninit() is called.
  22
  23   @param[in,out] VirtioFs  The Virtio Filesystem device to send the FUSE_LOOKUP
  24                            request to. On output, the FUSE request counter
  25                            "VirtioFs->RequestId" will have been incremented.
  26
  27   @param[in] DirNodeId     The inode number of the directory in which Name
  28                            should be resolved to an inode.
  29
  30   @param[in] Name          The single-component filename to resolve in the
  31                            directory identified by DirNodeId.
  32
  33   @param[out] NodeId       The inode number which Name has been resolved to.
  34
  35   @param[out] FuseAttr     The VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE object
  36                            describing the properties of the resolved inode.
  37
  38   @retval EFI_SUCCESS    Filename to inode resolution successful.
  39
  40   @retval EFI_NOT_FOUND  The Virtio Filesystem device explicitly reported
  41                          ENOENT -- "No such file or directory".
  42
  43   @return                The "errno" value mapped to an EFI_STATUS code, if the
  44                          Virtio Filesystem device explicitly reported an error
  45                          different from ENOENT. If said mapping resulted in
  46                          EFI_NOT_FOUND, it is remapped to EFI_DEVICE_ERROR.
  47
  48   @return                Error codes propagated from VirtioFsSgListsValidate(),
  49                          VirtioFsFuseNewRequest(), VirtioFsSgListsSubmit(),
  50                          VirtioFsFuseCheckResponse(). EFI_NOT_FOUND is remapped
  51                          to EFI_DEVICE_ERROR.
  52 **/
  53 EFI_STATUS
  54 VirtioFsFuseLookup (
  55   IN OUT VIRTIO_FS                        *VirtioFs,
  56   IN     UINT64                           DirNodeId,
  57   IN     CHAR8                            *Name,
  58   OUT UINT64                              *NodeId,
  59   OUT VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE  *FuseAttr
  60   )
  61 {
  62   VIRTIO_FS_FUSE_REQUEST         CommonReq;
  63   VIRTIO_FS_IO_VECTOR            ReqIoVec[2];
  64   VIRTIO_FS_SCATTER_GATHER_LIST  ReqSgList;
  65   VIRTIO_FS_FUSE_RESPONSE        CommonResp;
  66   VIRTIO_FS_FUSE_NODE_RESPONSE   NodeResp;
  67   VIRTIO_FS_IO_VECTOR            RespIoVec[3];
  68   VIRTIO_FS_SCATTER_GATHER_LIST  RespSgList;
  69   EFI_STATUS                     Status;
  70
  71   //
  72   // Set up the scatter-gather lists.
  73   //
  74   ReqIoVec[0].Buffer = &CommonReq;
  75   ReqIoVec[0].Size   = sizeof CommonReq;
  76   ReqIoVec[1].Buffer = Name;
  77   ReqIoVec[1].Size   = AsciiStrSize (Name);
  78   ReqSgList.IoVec    = ReqIoVec;
  79   ReqSgList.NumVec   = ARRAY_SIZE (ReqIoVec);
  80
  81   RespIoVec[0].Buffer = &CommonResp;
  82   RespIoVec[0].Size   = sizeof CommonResp;
  83   RespIoVec[1].Buffer = &NodeResp;
  84   RespIoVec[1].Size   = sizeof NodeResp;
  85   RespIoVec[2].Buffer = FuseAttr;
  86   RespIoVec[2].Size   = sizeof *FuseAttr;
  87   RespSgList.IoVec    = RespIoVec;
  88   RespSgList.NumVec   = ARRAY_SIZE (RespIoVec);
  89
  90   //
  91   // Validate the scatter-gather lists; calculate the total transfer sizes.
  92   //
  93   Status = VirtioFsSgListsValidate (VirtioFs, &ReqSgList, &RespSgList);
  94   if (EFI_ERROR (Status)) {
  95     goto Fail;
  96   }
  97
  98   //
  99   // Populate the common request header.
 100   //
 101   Status = VirtioFsFuseNewRequest (
 102              VirtioFs,
 103              &CommonReq,
 104              ReqSgList.TotalSize,
 105              VirtioFsFuseOpLookup,
 106              DirNodeId
 107              );
 108   if (EFI_ERROR (Status)) {
 109     goto Fail;
 110   }
 111
 112   //
 113   // Submit the request.
 114   //
 115   Status = VirtioFsSgListsSubmit (VirtioFs, &ReqSgList, &RespSgList);
 116   if (EFI_ERROR (Status)) {
 117     goto Fail;
 118   }
 119
 120   //
 121   // Verify the response (all response buffers are fixed size).
 122   //
 123   Status = VirtioFsFuseCheckResponse (&RespSgList, CommonReq.Unique, NULL);
 124   if (EFI_ERROR (Status)) {
 125     if (Status == EFI_DEVICE_ERROR) {
 126       DEBUG ((
 127         ((CommonResp.Error == VIRTIO_FS_FUSE_ERRNO_ENOENT) ?
 128          DEBUG_VERBOSE :
 129          DEBUG_ERROR),
 130         "%a: Label=\"%s\" DirNodeId=%Lu Name=\"%a\" Errno=%d\n",
 131         __FUNCTION__,
 132         VirtioFs->Label,
 133         DirNodeId,
 134         Name,
 135         CommonResp.Error
 136         ));
 137       if (CommonResp.Error == VIRTIO_FS_FUSE_ERRNO_ENOENT) {
 138         return EFI_NOT_FOUND;
 139       }
 140
 141       Status = VirtioFsErrnoToEfiStatus (CommonResp.Error);
 142     }
 143
 144     goto Fail;
 145   }
 146
 147   //
 148   // Output the NodeId to which Name has been resolved to.
 149   //
 150   *NodeId = NodeResp.NodeId;
 151   return EFI_SUCCESS;
 152
 153 Fail:
 154   return (Status == EFI_NOT_FOUND) ? EFI_DEVICE_ERROR : Status;
 155 }