[Virtio-fs] [edk2 PATCH 06/48] OvmfPkg/VirtioFsDxe: introduce the basic FUSE request/response headers
Dr. David Alan Gilbert
dgilbert at redhat.com
Thu Dec 17 11:49:50 UTC 2020
* Laszlo Ersek (lersek at redhat.com) wrote:
> 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 at arm.com>
> Cc: Jordan Justen <jordan.l.justen at intel.com>
> Cc: Philippe Mathieu-Daudé <philmd at redhat.com>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3097
> Signed-off-by: Laszlo Ersek <lersek at redhat.com>
> ---
> OvmfPkg/Include/IndustryStandard/VirtioFs.h | 49 +++++
> OvmfPkg/VirtioFsDxe/VirtioFsDxe.h | 17 ++
> OvmfPkg/VirtioFsDxe/DriverBinding.c | 5 +
> OvmfPkg/VirtioFsDxe/Helpers.c | 216 ++++++++++++++++++++
> 4 files changed, 287 insertions(+)
>
> diff --git a/OvmfPkg/Include/IndustryStandard/VirtioFs.h b/OvmfPkg/Include/IndustryStandard/VirtioFs.h
> index ea7d80d15d0b..521288b03f1c 100644
> --- a/OvmfPkg/Include/IndustryStandard/VirtioFs.h
> +++ b/OvmfPkg/Include/IndustryStandard/VirtioFs.h
> @@ -44,9 +44,58 @@ typedef struct {
> //
> // The total number of request virtqueues exposed by the device (i.e.,
> // excluding the "hiprio" queue).
> //
> UINT32 NumReqQueues;
> } 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).
Fuse has it's own in built protocol versioning and negotiation, and as I
remember it's the version of the header in the Linux kernel that's the
definitive version. I think it would have also been safe just to take
the latest released kernel version
Dave
> +// 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_
> diff --git a/OvmfPkg/VirtioFsDxe/VirtioFsDxe.h b/OvmfPkg/VirtioFsDxe/VirtioFsDxe.h
> index 12acbd6dc359..f7eae9a4b71a 100644
> --- a/OvmfPkg/VirtioFsDxe/VirtioFsDxe.h
> +++ b/OvmfPkg/VirtioFsDxe/VirtioFsDxe.h
> @@ -39,16 +39,17 @@ typedef struct {
> // field init function init depth
> // ----------- ------------------ ----------
> UINT64 Signature; // DriverBindingStart 0
> VIRTIO_DEVICE_PROTOCOL *Virtio; // DriverBindingStart 0
> VIRTIO_FS_LABEL Label; // VirtioFsInit 1
> 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;
>
> #define VIRTIO_FS_FROM_SIMPLE_FS(SimpleFsReference) \
> CR (SimpleFsReference, VIRTIO_FS, SimpleFs, VIRTIO_FS_SIG);
>
> //
> @@ -127,16 +128,32 @@ VirtioFsSgListsValidate (
>
> EFI_STATUS
> VirtioFsSgListsSubmit (
> IN OUT VIRTIO_FS *VirtioFs,
> IN OUT VIRTIO_FS_SCATTER_GATHER_LIST *RequestSgList,
> 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.
> //
>
> EFI_STATUS
> EFIAPI
> VirtioFsOpenVolume (
> diff --git a/OvmfPkg/VirtioFsDxe/DriverBinding.c b/OvmfPkg/VirtioFsDxe/DriverBinding.c
> index b888158a805d..4a2787a50a6e 100644
> --- a/OvmfPkg/VirtioFsDxe/DriverBinding.c
> +++ b/OvmfPkg/VirtioFsDxe/DriverBinding.c
> @@ -79,16 +79,21 @@ VirtioFsBindingStart (
> goto FreeVirtioFs;
> }
>
> Status = VirtioFsInit (VirtioFs);
> if (EFI_ERROR (Status)) {
> 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)) {
> goto UninitVirtioFs;
> }
>
> VirtioFs->SimpleFs.Revision = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_REVISION;
> VirtioFs->SimpleFs.OpenVolume = VirtioFsOpenVolume;
> diff --git a/OvmfPkg/VirtioFsDxe/Helpers.c b/OvmfPkg/VirtioFsDxe/Helpers.c
> index 88264d4b264c..5bd2dc641f6d 100644
> --- a/OvmfPkg/VirtioFsDxe/Helpers.c
> +++ b/OvmfPkg/VirtioFsDxe/Helpers.c
> @@ -693,8 +693,224 @@ VirtioFsSgListsSubmit (
> if (!EFI_ERROR (Status) && EFI_ERROR (UnmapStatus)) {
> Status = UnmapStatus;
> }
> }
> }
>
> 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;
> +}
> --
> 2.19.1.3.g30247aa5d201
>
>
>
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--
Dr. David Alan Gilbert / dgilbert at redhat.com / Manchester, UK
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