[edk2-devel] [edk2 PATCH 42/48] OvmfPkg/VirtioFsDxe: add helper for composing rename/move destination path
Laszlo Ersek
lersek at redhat.com
Wed Dec 16 21:11:19 UTC 2020
The EFI_FILE_PROTOCOL.SetInfo() member is somewhat under-specified; one of
its modes of operation is renaming/moving the file.
In order to create the destination pathname in canonical format, 2*2=4
cases have to be considered. For the sake of discussion, assume the
current canonical pathname of a VIRTIO_FS_FILE is "/home/user/f1.txt".
Then, consider the following rename/move requests from
EFI_FILE_PROTOCOL.SetInfo():
Destination requested Destination Move into Destination in
by SetInfo() relative? directory? canonical format
--------------------- ----------- ---------- -----------------------
L"\\dir\\f2.txt" no no "/dir/f2.txt"
L"\\dir\\" no yes "/dir/f1.txt"
L"dir\\f2.txt" yes no "/home/user/dir/f2.txt"
L"dir\\" yes yes "/home/user/dir/f1.txt"
Add the VirtioFsComposeRenameDestination() function, for composing the
last column from the current canonical pathname and the SetInfo() input.
The function works on the following principles:
- The prefix of the destination path is "/", if the SetInfo() rename
request is absolute.
Otherwise, the dest prefix is the "current directory" (the most specific
parent directory) of the original pathname (in the above example,
"/home/user").
- The suffix of the destination path is precisely the SetInfo() request
string, if the "move into directory" convenience format -- the trailing
backslash -- is not used. (In the above example, L"\\dir\\f2.txt" and
L"dir\\f2.txt".)
Otherwise, the suffix is the SetInfo() request, plus the original
basename (in the above example, L"\\dir\\f1.txt" and L"dir\\f1.txt").
- The complete destination is created by fusing the dest prefix and the
dest suffix, using the VirtioFsAppendPath() function.
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/VirtioFsDxe/VirtioFsDxe.h | 8 +
OvmfPkg/VirtioFsDxe/Helpers.c | 194 ++++++++++++++++++++
2 files changed, 202 insertions(+)
diff --git a/OvmfPkg/VirtioFsDxe/VirtioFsDxe.h b/OvmfPkg/VirtioFsDxe/VirtioFsDxe.h
index 9334e5434c51..a6dfac71f4a7 100644
--- a/OvmfPkg/VirtioFsDxe/VirtioFsDxe.h
+++ b/OvmfPkg/VirtioFsDxe/VirtioFsDxe.h
@@ -257,16 +257,24 @@ VirtioFsLookupMostSpecificParentDir (
EFI_STATUS
VirtioFsGetBasename (
IN CHAR8 *Path,
OUT CHAR16 *Basename OPTIONAL,
IN OUT UINTN *BasenameSize
);
+EFI_STATUS
+VirtioFsComposeRenameDestination (
+ IN CHAR8 *LhsPath8,
+ IN CHAR16 *RhsPath16,
+ OUT CHAR8 **ResultPath8,
+ OUT BOOLEAN *RootEscape
+ );
+
EFI_STATUS
VirtioFsFuseAttrToEfiFileInfo (
IN VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE *FuseAttr,
OUT EFI_FILE_INFO *FileInfo
);
EFI_STATUS
VirtioFsFuseDirentPlusToEfiFileInfo (
diff --git a/OvmfPkg/VirtioFsDxe/Helpers.c b/OvmfPkg/VirtioFsDxe/Helpers.c
index cdaa8557a17b..b741cf753495 100644
--- a/OvmfPkg/VirtioFsDxe/Helpers.c
+++ b/OvmfPkg/VirtioFsDxe/Helpers.c
@@ -1778,16 +1778,210 @@ VirtioFsGetBasename (
}
for (Idx = LastComponent; Idx < PathSize; Idx++) {
Basename[Idx - LastComponent] = Path[Idx];
}
return EFI_SUCCESS;
}
+/**
+ Format the destination of a rename/move operation as a dynamically allocated
+ canonical pathname.
+
+ Any dot-dot in RhsPath16 that would remove the root directory is dropped, and
+ reported through RootEscape, without failing the function call.
+
+ @param[in] LhsPath8 The source pathname operand of the rename/move
+ operation, expressed as a canonical pathname (as
+ defined in the description of VirtioFsAppendPath()).
+ The root directory "/" cannot be renamed/moved, and
+ will be rejected.
+
+ @param[in] RhsPath16 The destination pathname operand expressed as a
+ UEFI-style CHAR16 pathname.
+
+ If RhsPath16 starts with a backslash, then RhsPath16
+ is considered absolute. Otherwise, RhsPath16 is
+ interpreted relative to the most specific parent
+ directory found in LhsPath8.
+
+ Independently, if RhsPath16 ends with a backslash
+ (i.e., RhsPath16 is given in the "move into
+ directory" convenience form), then RhsPath16 is
+ interpreted with the basename of LhsPath8 appended.
+ Otherwise, the last pathname component of RhsPath16
+ is taken as the last pathname component of the
+ rename/move destination.
+
+ An empty RhsPath16 is rejected.
+
+ @param[out] ResultPath8 The POSIX-style, canonical format pathname that
+ leads to the renamed/moved file. After use, the
+ caller is responsible for freeing ResultPath8.
+
+ @param[out] RootEscape Set to TRUE if at least one dot-dot component in
+ RhsPath16 attempted to escape the root directory;
+ set to FALSE otherwise.
+
+ @retval EFI_SUCCESS ResultPath8 has been produced. RootEscape has
+ been output.
+
+ @retval EFI_INVALID_PARAMETER LhsPath8 is "/".
+
+ @retval EFI_INVALID_PARAMETER RhsPath16 is zero-length.
+
+ @retval EFI_INVALID_PARAMETER RhsPath16 failed the
+ VIRTIO_FS_MAX_PATHNAME_LENGTH check.
+
+ @retval EFI_OUT_OF_RESOURCES Memory allocation failed.
+
+ @retval EFI_OUT_OF_RESOURCES ResultPath8 would have failed the
+ VIRTIO_FS_MAX_PATHNAME_LENGTH check.
+
+ @retval EFI_UNSUPPORTED RhsPath16 contains a character that either
+ falls outside of the printable ASCII set, or
+ is a forward slash.
+**/
+EFI_STATUS
+VirtioFsComposeRenameDestination (
+ IN CHAR8 *LhsPath8,
+ IN CHAR16 *RhsPath16,
+ OUT CHAR8 **ResultPath8,
+ OUT BOOLEAN *RootEscape
+ )
+{
+ //
+ // Lengths are expressed as numbers of characters (CHAR8 or CHAR16),
+ // excluding terminating NULs. Sizes are expressed as byte counts, including
+ // the bytes taken up by terminating NULs.
+ //
+ UINTN RhsLen;
+ UINTN LhsBasename16Size;
+ EFI_STATUS Status;
+ UINTN LhsBasenameLen;
+ UINTN DestSuffix16Size;
+ CHAR16 *DestSuffix16;
+ CHAR8 *DestPrefix8;
+
+ //
+ // An empty destination operand for the rename/move operation is not allowed.
+ //
+ RhsLen = StrLen (RhsPath16);
+ if (RhsLen == 0) {
+ return EFI_INVALID_PARAMETER;
+ }
+ //
+ // Enforce length restriction on RhsPath16.
+ //
+ if (RhsLen > VIRTIO_FS_MAX_PATHNAME_LENGTH) {
+ return EFI_INVALID_PARAMETER;
+ }
+
+ //
+ // Determine the length of the basename of LhsPath8.
+ //
+ LhsBasename16Size = 0;
+ Status = VirtioFsGetBasename (LhsPath8, NULL, &LhsBasename16Size);
+ ASSERT (Status == EFI_BUFFER_TOO_SMALL);
+ ASSERT (LhsBasename16Size >= sizeof (CHAR16));
+ ASSERT (LhsBasename16Size % sizeof (CHAR16) == 0);
+ LhsBasenameLen = LhsBasename16Size / sizeof (CHAR16) - 1;
+ if (LhsBasenameLen == 0) {
+ //
+ // The root directory cannot be renamed/moved.
+ //
+ return EFI_INVALID_PARAMETER;
+ }
+
+ //
+ // Resolve the "move into directory" convenience form in RhsPath16.
+ //
+ if (RhsPath16[RhsLen - 1] == L'\\') {
+ //
+ // Append the basename of LhsPath8 as a CHAR16 string to RhsPath16.
+ //
+ DestSuffix16Size = RhsLen * sizeof (CHAR16) + LhsBasename16Size;
+ DestSuffix16 = AllocatePool (DestSuffix16Size);
+ if (DestSuffix16 == NULL) {
+ return EFI_OUT_OF_RESOURCES;
+ }
+ CopyMem (DestSuffix16, RhsPath16, RhsLen * sizeof (CHAR16));
+ Status = VirtioFsGetBasename (LhsPath8, DestSuffix16 + RhsLen,
+ &LhsBasename16Size);
+ ASSERT_EFI_ERROR (Status);
+ } else {
+ //
+ // Just create a copy of RhsPath16.
+ //
+ DestSuffix16Size = (RhsLen + 1) * sizeof (CHAR16);
+ DestSuffix16 = AllocateCopyPool (DestSuffix16Size, RhsPath16);
+ if (DestSuffix16 == NULL) {
+ return EFI_OUT_OF_RESOURCES;
+ }
+ }
+
+ //
+ // If the destination operand is absolute, it will be interpreted relative to
+ // the root directory.
+ //
+ // Otherwise (i.e., if the destination operand is relative), then create the
+ // canonical pathname that the destination operand is interpreted relatively
+ // to; that is, the canonical pathname of the most specific parent directory
+ // found in LhsPath8.
+ //
+ if (DestSuffix16[0] == L'\\') {
+ DestPrefix8 = AllocateCopyPool (sizeof "/", "/");
+ if (DestPrefix8 == NULL) {
+ Status = EFI_OUT_OF_RESOURCES;
+ goto FreeDestSuffix16;
+ }
+ } else {
+ UINTN LhsLen;
+ UINTN DestPrefixLen;
+
+ //
+ // Strip the basename of LhsPath8.
+ //
+ LhsLen = AsciiStrLen (LhsPath8);
+ ASSERT (LhsBasenameLen < LhsLen);
+ DestPrefixLen = LhsLen - LhsBasenameLen;
+ ASSERT (LhsPath8[DestPrefixLen - 1] == '/');
+ //
+ // If we're not at the root directory, strip the slash too.
+ //
+ if (DestPrefixLen > 1) {
+ DestPrefixLen--;
+ }
+ DestPrefix8 = AllocatePool (DestPrefixLen + 1);
+ if (DestPrefix8 == NULL) {
+ Status = EFI_OUT_OF_RESOURCES;
+ goto FreeDestSuffix16;
+ }
+ CopyMem (DestPrefix8, LhsPath8, DestPrefixLen);
+ DestPrefix8[DestPrefixLen] = '\0';
+ }
+
+ //
+ // Now combine DestPrefix8 and DestSuffix16 into the final canonical
+ // pathname.
+ //
+ Status = VirtioFsAppendPath (DestPrefix8, DestSuffix16, ResultPath8,
+ RootEscape);
+
+ FreePool (DestPrefix8);
+ //
+ // Fall through.
+ //
+FreeDestSuffix16:
+ FreePool (DestSuffix16);
+
+ return Status;
+}
+
/**
Convert select fields of a VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE object to
corresponding fields in EFI_FILE_INFO.
@param[in] FuseAttr The VIRTIO_FS_FUSE_ATTRIBUTES_RESPONSE object to
convert the relevant fields from.
@param[out] FileInfo The EFI_FILE_INFO structure to modify. Importantly, the
--
2.19.1.3.g30247aa5d201
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