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OvmfPkg/VirtioFsDxe: introduce the basic FUSE request/response headers 

Introduce the VIRTIO_FS_FUSE_REQUEST and VIRTIO_FS_FUSE_RESPONSE
structures, which are the common headers for the various FUSE
request/response structures.

Introduce the VirtioFsFuseNewRequest() helper function for populating
VIRTIO_FS_FUSE_REQUEST, from parameters and from a VIRTIO_FS-level request
counter.

Introduce the VirtioFsFuseCheckResponse() helper function for verifying
most FUSE response types that begin with the VIRTIO_FS_FUSE_RESPONSE
header.

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3097
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20201216211125.19496-7-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
This commit is contained in:
Laszlo Ersek 2020-12-16 22:10:43 +01:00 committed by mergify[bot]
parent 6578cacb46
commit 6a2dc768f0
4 changed files with 287 additions and 0 deletions
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49
OvmfPkg/Include/IndustryStandard/VirtioFs.h
View File

@ -49,4 +49,53 @@ typedef struct {
} VIRTIO_FS_CONFIG;
#pragma pack ()
//
// FUSE-related definitions follow.
//
// From virtio-v1.1-cs01-87fa6b5d8155, 5.11 File System Device: "[...] The
// driver acts as the FUSE client mounting the file system. The virtio file
// system device provides the mechanism for transporting FUSE requests [...]"
//
// Unfortunately, the documentation of the FUSE wire protocol is lacking. The
// Virtio spec (as of this writing) simply defers to
// "include/uapi/linux/fuse.h" in the Linux kernel source -- see the reference
// in virtio spec file "introduction.tex", at commit 87fa6b5d8155.
//
// Of course, "include/uapi/linux/fuse.h" is a moving target (the virtio spec
// does not specify a particular FUSE interface version). The OvmfPkg code
// targets version 7.31, because that's the lowest version that the QEMU
// virtio-fs daemon supports at this time -- see QEMU commit 72c42e2d6551
// ("virtiofsd: Trim out compatibility code", 2020-01-23).
//
// Correspondingly, Linux's "include/uapi/linux/fuse.h" is consulted as checked
// out at commit (c6ff213fe5b8^) = d78092e4937d ("fuse: fix page dereference
// after free", 2020-09-18); that is, right before commit c6ff213fe5b8 ("fuse:
// add submount support to <uapi/linux/fuse.h>", 2020-09-18) introduces FUSE
// interface version 7.32.
//
#define VIRTIO_FS_FUSE_MAJOR 7
#define VIRTIO_FS_FUSE_MINOR 31
#pragma pack (1)
//
// Request-response headers common to all request types.
//
typedef struct {
UINT32 Len;
UINT32 Opcode;
UINT64 Unique;
UINT64 NodeId;
UINT32 Uid;
UINT32 Gid;
UINT32 Pid;
UINT32 Padding;
} VIRTIO_FS_FUSE_REQUEST;
typedef struct {
UINT32 Len;
INT32 Error;
UINT64 Unique;
} VIRTIO_FS_FUSE_RESPONSE;
#pragma pack ()
#endif // VIRTIO_FS_H_

5
OvmfPkg/VirtioFsDxe/DriverBinding.c
View File

@ -84,6 +84,11 @@ VirtioFsBindingStart (
goto CloseVirtio;
}
//
// Initialize the FUSE request counter.
//
VirtioFs->RequestId = 1;
Status = gBS->CreateEvent (EVT_SIGNAL_EXIT_BOOT_SERVICES, TPL_CALLBACK,
VirtioFsExitBoot, VirtioFs, &VirtioFs->ExitBoot);
if (EFI_ERROR (Status)) {

216
OvmfPkg/VirtioFsDxe/Helpers.c
View File

@ -698,3 +698,219 @@ Unmap:
return Status;
}
/**
Set up the fields of a new VIRTIO_FS_FUSE_REQUEST object.
The function may only be called after VirtioFsInit() returns successfully and
before VirtioFsUninit() is called.
@param[in,out] VirtioFs The Virtio Filesystem device that the request is
being prepared for. The "VirtioFs->RequestId" field
will be copied into "Request->Unique". On output (on
successful return), "VirtioFs->RequestId" will be
incremented.
@param[out] Request The VIRTIO_FS_FUSE_REQUEST object whose fields are to
be set.
@param[in] RequestSize The total size of the request, including
sizeof(VIRTIO_FS_FUSE_REQUEST).
@param[in] Opcode The VIRTIO_FS_FUSE_OPCODE that identifies the command
to send.
@param[in] NodeId The inode number of the file that the request refers
to.
@retval EFI_INVALID_PARAMETER RequestSize is smaller than
sizeof(VIRTIO_FS_FUSE_REQUEST).
@retval EFI_OUT_OF_RESOURCES "VirtioFs->RequestId" is MAX_UINT64, and can
be incremented no more.
@retval EFI_SUCCESS Request has been populated,
"VirtioFs->RequestId" has been incremented.
**/
EFI_STATUS
VirtioFsFuseNewRequest (
IN OUT VIRTIO_FS *VirtioFs,
OUT VIRTIO_FS_FUSE_REQUEST *Request,
IN UINT32 RequestSize,
IN UINT32 Opcode,
IN UINT64 NodeId
)
{
if (RequestSize < sizeof *Request) {
return EFI_INVALID_PARAMETER;
}
if (VirtioFs->RequestId == MAX_UINT64) {
return EFI_OUT_OF_RESOURCES;
}
Request->Len = RequestSize;
Request->Opcode = Opcode;
Request->Unique = VirtioFs->RequestId++;
Request->NodeId = NodeId;
Request->Uid = 0;
Request->Gid = 0;
Request->Pid = 1;
Request->Padding = 0;
return EFI_SUCCESS;
}
/**
Check the common FUSE response format.
The first buffer in the response scatter-gather list is assumed a
VIRTIO_FS_FUSE_RESPONSE structure. Subsequent response buffers, if any, up to
and excluding the last one, are assumed fixed size. The last response buffer
may or may not be fixed size, as specified by the caller.
This function may only be called after VirtioFsSgListsSubmit() returns
successfully.
@param[in] ResponseSgList The scatter-gather list that describes the
response part of the exchange -- the buffers that
the Virtio Filesystem device filled in during the
virtio transfer.
@param[in] RequestId The request identifier to which the response is
expected to belong.
@param[out] TailBufferFill If NULL, then the last buffer in ResponseSgList
is considered fixed size. Otherwise, the last
buffer is considered variable size, and on
successful return, TailBufferFill reports the
number of bytes in the last buffer.
@retval EFI_INVALID_PARAMETER TailBufferFill is not NULL (i.e., the last
buffer is considered variable size), and
ResponseSgList->NumVec is 1.
@retval EFI_INVALID_PARAMETER The allocated size of the first buffer does
not match sizeof(VIRTIO_FS_FUSE_RESPONSE).
@retval EFI_PROTOCOL_ERROR The VIRTIO_FS_FUSE_RESPONSE structure in the
first buffer has not been fully populated.
@retval EFI_PROTOCOL_ERROR "VIRTIO_FS_FUSE_RESPONSE.Len" in the first
buffer does not equal the sum of the
individual buffer sizes (as populated).
@retval EFI_PROTOCOL_ERROR "VIRTIO_FS_FUSE_RESPONSE.Unique" in the first
buffer does not equal RequestId.
@retval EFI_PROTOCOL_ERROR "VIRTIO_FS_FUSE_RESPONSE.Error" in the first
buffer is zero, but a subsequent fixed size
buffer has not been fully populated.
@retval EFI_DEVICE_ERROR "VIRTIO_FS_FUSE_RESPONSE.Error" in the first
buffer is nonzero. The caller may investigate
"VIRTIO_FS_FUSE_RESPONSE.Error". Note that the
completeness of the subsequent fixed size
buffers is not verified in this case.
@retval EFI_SUCCESS Verification successful.
**/
EFI_STATUS
VirtioFsFuseCheckResponse (
IN VIRTIO_FS_SCATTER_GATHER_LIST *ResponseSgList,
IN UINT64 RequestId,
OUT UINTN *TailBufferFill
)
{
UINTN NumFixedSizeVec;
VIRTIO_FS_FUSE_RESPONSE *CommonResp;
UINT32 TotalTransferred;
UINTN Idx;
//
// Ensured by VirtioFsSgListsValidate().
//
ASSERT (ResponseSgList->NumVec > 0);
if (TailBufferFill == NULL) {
//
// All buffers are considered fixed size.
//
NumFixedSizeVec = ResponseSgList->NumVec;
} else {
//
// If the last buffer is variable size, then we need that buffer to be
// different from the first buffer, which is considered a
// VIRTIO_FS_FUSE_RESPONSE (fixed size) structure.
//
if (ResponseSgList->NumVec == 1) {
return EFI_INVALID_PARAMETER;
}
NumFixedSizeVec = ResponseSgList->NumVec - 1;
}
//
// The first buffer is supposed to carry a (fully populated)
// VIRTIO_FS_FUSE_RESPONSE structure.
//
if (ResponseSgList->IoVec[0].Size != sizeof *CommonResp) {
return EFI_INVALID_PARAMETER;
}
if (ResponseSgList->IoVec[0].Transferred != ResponseSgList->IoVec[0].Size) {
return EFI_PROTOCOL_ERROR;
}
//
// FUSE must report the same number of bytes, written by the Virtio
// Filesystem device, as the virtio transport does.
//
CommonResp = ResponseSgList->IoVec[0].Buffer;
TotalTransferred = 0;
for (Idx = 0; Idx < ResponseSgList->NumVec; Idx++) {
//
// Integer overflow and truncation are not possible, based on
// VirtioFsSgListsValidate() and VirtioFsSgListsSubmit().
//
TotalTransferred += (UINT32)ResponseSgList->IoVec[Idx].Transferred;
}
if (CommonResp->Len != TotalTransferred) {
return EFI_PROTOCOL_ERROR;
}
//
// Enforce that FUSE match our request ID in the response.
//
if (CommonResp->Unique != RequestId) {
return EFI_PROTOCOL_ERROR;
}
//
// If there is an explicit error report, skip checking the transfer
// counts for the rest of the fixed size buffers.
//
if (CommonResp->Error != 0) {
return EFI_DEVICE_ERROR;
}
//
// There was no error reported, so we require that the Virtio Filesystem
// device populate all fixed size buffers. We checked this for the very first
// buffer above; let's check the rest (if any).
//
ASSERT (NumFixedSizeVec >= 1);
for (Idx = 1; Idx < NumFixedSizeVec; Idx++) {
if (ResponseSgList->IoVec[Idx].Transferred !=
ResponseSgList->IoVec[Idx].Size) {
return EFI_PROTOCOL_ERROR;
}
}
//
// If the last buffer is considered variable size, report its filled size.
//
if (TailBufferFill != NULL) {
*TailBufferFill = ResponseSgList->IoVec[NumFixedSizeVec].Transferred;
}
return EFI_SUCCESS;
}

17
OvmfPkg/VirtioFsDxe/VirtioFsDxe.h
View File

@ -44,6 +44,7 @@ typedef struct {
UINT16 QueueSize; // VirtioFsInit 1
VRING Ring; // VirtioRingInit 2
VOID *RingMap; // VirtioRingMap 2
UINT64 RequestId; // DriverBindingStart 0
EFI_EVENT ExitBoot; // DriverBindingStart 0
EFI_SIMPLE_FILE_SYSTEM_PROTOCOL SimpleFs; // DriverBindingStart 0
} VIRTIO_FS;
@ -132,6 +133,22 @@ VirtioFsSgListsSubmit (
IN OUT VIRTIO_FS_SCATTER_GATHER_LIST *ResponseSgList OPTIONAL
);
EFI_STATUS
VirtioFsFuseNewRequest (
IN OUT VIRTIO_FS *VirtioFs,
OUT VIRTIO_FS_FUSE_REQUEST *Request,
IN UINT32 RequestSize,
IN UINT32 Opcode,
IN UINT64 NodeId
);
EFI_STATUS
VirtioFsFuseCheckResponse (
IN VIRTIO_FS_SCATTER_GATHER_LIST *ResponseSgList,
IN UINT64 RequestId,
OUT UINTN *TailBufferFill
);
//
// EFI_SIMPLE_FILE_SYSTEM_PROTOCOL member functions for the Virtio Filesystem
// driver.