[Virtio-fs] [edk2 PATCH 06/48] OvmfPkg/VirtioFsDxe: introduce the basic FUSE request/response headers
Laszlo Ersek
lersek at redhat.com
Wed Dec 16 21:10:43 UTC 2020
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).
+//
+// 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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