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

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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_