* [edk2-platforms][PATCH v5 1/2] Ext4Pkg: Add symbolic links support
2022-09-07 14:02 [edk2-platforms][PATCH v5 0/2] Ext4Pkg: Add Symbolic Links support Savva Mitrofanov
@ 2022-09-07 14:02 ` Savva Mitrofanov
2022-09-07 14:02 ` [edk2-platforms][PATCH v5 2/2] Ext4Pkg: Add base containing record macro for EXT4_FILE Savva Mitrofanov
2022-09-15 21:00 ` [edk2-platforms][PATCH v5 0/2] Ext4Pkg: Add Symbolic Links support Pedro Falcato
2 siblings, 0 replies; 5+ messages in thread
From: Savva Mitrofanov @ 2022-09-07 14:02 UTC (permalink / raw)
To: devel; +Cc: Marvin Häuser, Pedro Falcato, Vitaly Cheptsov
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3677
Provided support for symlink file type. Added routine which allows
reading and following them through recursive open() call. As a security
meausure implemented simple symlink loop check with nest level limit
equal 8. Also this patch moves Ext4Open functionality to internal
routine.
Cc: Marvin Häuser <mhaeuser@posteo.de>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Cc: Vitaly Cheptsov <vit9696@protonmail.com>
Signed-off-by: Savva Mitrofanov <savvamtr@gmail.com>
---
Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.inf | 1 +
Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h | 13 +-
Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h | 72 +++++-
Features/Ext4Pkg/Ext4Dxe/File.c | 169 +++++++++++--
Features/Ext4Pkg/Ext4Dxe/Inode.c | 15 ++
Features/Ext4Pkg/Ext4Dxe/Symlink.c | 261 ++++++++++++++++++++
6 files changed, 492 insertions(+), 39 deletions(-)
diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.inf b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.inf
index deaf89fb3743..a153fc41ccd6 100644
--- a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.inf
+++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.inf
@@ -108,6 +108,7 @@
Directory.c
Extents.c
File.c
+ Symlink.c
Collation.c
Ext4Disk.h
Ext4Dxe.h
diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h b/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h
index 7a19d2f79d53..4fd91a423324 100644
--- a/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h
+++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h
@@ -171,7 +171,7 @@
#define EXT4_DIRTY_FL 0x00000100
#define EXT4_COMPRBLK_FL 0x00000200
#define EXT4_NOCOMPR_FL 0x00000400
-#define EXT4_ECOMPR_FL 0x00000800
+#define EXT4_ENCRYPT_FL 0x00000800
#define EXT4_BTREE_FL 0x00001000
#define EXT4_INDEX_FL 0x00002000
#define EXT4_JOURNAL_DATA_FL 0x00004000
@@ -332,11 +332,12 @@ STATIC_ASSERT (
"ext4 block group descriptor struct has incorrect size"
);
-#define EXT4_DBLOCKS 12
-#define EXT4_IND_BLOCK 12
-#define EXT4_DIND_BLOCK 13
-#define EXT4_TIND_BLOCK 14
-#define EXT4_NR_BLOCKS 15
+#define EXT4_DBLOCKS 12
+#define EXT4_IND_BLOCK 12
+#define EXT4_DIND_BLOCK 13
+#define EXT4_TIND_BLOCK 14
+#define EXT4_NR_BLOCKS 15
+#define EXT4_FAST_SYMLINK_MAX_SIZE EXT4_NR_BLOCKS * sizeof(UINT32)
#define EXT4_GOOD_OLD_INODE_SIZE 128U
diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
index 81e59a4babc9..6d352d3995f1 100644
--- a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
+++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
@@ -31,8 +31,14 @@
#include "Ext4Disk.h"
+#define SYMLOOP_MAX 8
#define EXT4_NAME_MAX 255
-
+//
+// We need to specify path length limit for security purposes, to prevent possible
+// overflows and dead-loop conditions. Originally this limit is absent in FS design,
+// but present in UNIX distros and shell environments, which may varies from 1024 to 4096.
+//
+#define EXT4_EFI_PATH_MAX 4096
#define EXT4_DRIVER_VERSION 0x0000
/**
@@ -324,11 +330,11 @@ number of read bytes.
**/
EFI_STATUS
Ext4Read (
- IN EXT4_PARTITION *Partition,
- IN EXT4_FILE *File,
- OUT VOID *Buffer,
- IN UINT64 Offset,
- IN OUT UINTN *Length
+ IN EXT4_PARTITION *Partition,
+ IN EXT4_FILE *File,
+ OUT VOID *Buffer,
+ IN UINT64 Offset,
+ IN OUT UINTN *Length
);
/**
@@ -368,6 +374,7 @@ struct _Ext4File {
UINT64 OpenMode;
UINT64 Position;
+ UINT32 SymLoops;
EXT4_PARTITION *Partition;
@@ -497,6 +504,45 @@ Ext4SetupFile (
IN EXT4_PARTITION *Partition
);
+/**
+ Opens a new file relative to the source file's location.
+
+ @param[out] FoundFile A pointer to the location to return the opened handle for the new
+ file.
+ @param[in] Source A pointer to the EXT4_FILE instance that is the file
+ handle to the source location. This would typically be an open
+ handle to a directory.
+ @param[in] FileName The Null-terminated string of the name of the file to be opened.
+ The file name may contain the following path modifiers: "\", ".",
+ and "..".
+ @param[in] OpenMode The mode to open the file. The only valid combinations that the
+ file may be opened with are: Read, Read/Write, or Create/Read/Write.
+ @param[in] Attributes Only valid for EFI_FILE_MODE_CREATE, in which case these are the
+ attribute bits for the newly created file.
+
+ @retval EFI_SUCCESS The file was opened.
+ @retval EFI_NOT_FOUND The specified file could not be found on the device.
+ @retval EFI_NO_MEDIA The device has no medium.
+ @retval EFI_MEDIA_CHANGED The device has a different medium in it or the medium is no
+ longer supported.
+ @retval EFI_DEVICE_ERROR The device reported an error.
+ @retval EFI_VOLUME_CORRUPTED The file system structures are corrupted.
+ @retval EFI_WRITE_PROTECTED An attempt was made to create a file, or open a file for write
+ when the media is write-protected.
+ @retval EFI_ACCESS_DENIED The service denied access to the file.
+ @retval EFI_OUT_OF_RESOURCES Not enough resources were available to open the file.
+ @retval EFI_VOLUME_FULL The volume is full.
+
+**/
+EFI_STATUS
+Ext4OpenInternal (
+ OUT EXT4_FILE **FoundFile,
+ IN EXT4_FILE *Source,
+ IN CHAR16 *FileName,
+ IN UINT64 OpenMode,
+ IN UINT64 Attributes
+ );
+
/**
Closes a file.
@@ -774,6 +820,18 @@ Ext4FileIsDir (
IN CONST EXT4_FILE *File
);
+/**
+ Checks if a file is a symlink.
+
+ @param[in] File Pointer to the opened file.
+
+ @return BOOLEAN Whether file is a symlink
+**/
+BOOLEAN
+Ext4FileIsSymlink (
+ IN CONST EXT4_FILE *File
+ );
+
/**
Checks if a file is a regular file.
@param[in] File Pointer to the opened file.
@@ -797,7 +855,7 @@ Ext4FileIsReg (
it's a regular file or a directory, since most other file types
don't make sense under UEFI.
**/
-#define Ext4FileIsOpenable(File) (Ext4FileIsReg(File) || Ext4FileIsDir(File))
+#define Ext4FileIsOpenable(File) (Ext4FileIsReg (File) || Ext4FileIsDir (File) || Ext4FileIsSymlink (File))
#define EXT4_INODE_HAS_FIELD(Inode, Field) \
(Inode->i_extra_isize + EXT4_GOOD_OLD_INODE_SIZE >= \
diff --git a/Features/Ext4Pkg/Ext4Dxe/File.c b/Features/Ext4Pkg/Ext4Dxe/File.c
index ff1746d5640a..86ccfff8603a 100644
--- a/Features/Ext4Pkg/Ext4Dxe/File.c
+++ b/Features/Ext4Pkg/Ext4Dxe/File.c
@@ -9,6 +9,26 @@
#include <Library/BaseUcs2Utf8Lib.h>
+/**
+ Reads a symlink file.
+
+ @param[in] Partition Pointer to the ext4 partition.
+ @param[in] File Pointer to the open symlink file.
+ @param[out] Symlink Pointer to the output unicode symlink string.
+
+ @retval EFI_SUCCESS Symlink was read.
+ @retval EFI_ACCESS_DENIED Symlink is encrypted.
+ @retval EFI_OUT_OF_RESOURCES Memory allocation error.
+ @retval EFI_INVALID_PARAMETER Symlink path has incorrect length
+ @retval EFI_VOLUME_CORRUPTED Symlink read block size differ from inode value
+**/
+EFI_STATUS
+Ext4ReadSymlink (
+ IN EXT4_PARTITION *Partition,
+ IN EXT4_FILE *File,
+ OUT CHAR16 **Symlink
+ );
+
/**
Duplicates a file structure.
@@ -137,11 +157,11 @@ Ext4DirCanLookup (
/**
Opens a new file relative to the source file's location.
- @param[in] This A pointer to the EFI_FILE_PROTOCOL instance that is the file
+ @param[out] FoundFile A pointer to the location to return the opened handle for the new
+ file.
+ @param[in] Source A pointer to the EXT4_FILE instance that is the file
handle to the source location. This would typically be an open
handle to a directory.
- @param[out] NewHandle A pointer to the location to return the opened handle for the new
- file.
@param[in] FileName The Null-terminated string of the name of the file to be opened.
The file name may contain the following path modifiers: "\", ".",
and "..".
@@ -165,13 +185,12 @@ Ext4DirCanLookup (
**/
EFI_STATUS
-EFIAPI
-Ext4Open (
- IN EFI_FILE_PROTOCOL *This,
- OUT EFI_FILE_PROTOCOL **NewHandle,
- IN CHAR16 *FileName,
- IN UINT64 OpenMode,
- IN UINT64 Attributes
+Ext4OpenInternal (
+ OUT EXT4_FILE **FoundFile,
+ IN EXT4_FILE *Source,
+ IN CHAR16 *FileName,
+ IN UINT64 OpenMode,
+ IN UINT64 Attributes
)
{
EXT4_FILE *Current;
@@ -180,13 +199,14 @@ Ext4Open (
CHAR16 PathSegment[EXT4_NAME_MAX + 1];
UINTN Length;
EXT4_FILE *File;
+ CHAR16 *Symlink;
EFI_STATUS Status;
- Current = (EXT4_FILE *)This;
+ Current = Source;
Partition = Current->Partition;
Level = 0;
- DEBUG ((DEBUG_FS, "[ext4] Ext4Open %s\n", FileName));
+ DEBUG ((DEBUG_FS, "[ext4] Ext4OpenInternal %s\n", FileName));
// If the path starts with a backslash, we treat the root directory as the base directory
if (FileName[0] == L'\\') {
FileName++;
@@ -194,6 +214,11 @@ Ext4Open (
}
while (FileName[0] != L'\0') {
+ if (Partition->Root->SymLoops > SYMLOOP_MAX) {
+ DEBUG ((DEBUG_FS, "[ext4] Symloop limit is hit !\n"));
+ return EFI_ACCESS_DENIED;
+ }
+
// Discard leading path separators
while (FileName[0] == L'\\') {
FileName++;
@@ -238,18 +263,45 @@ Ext4Open (
}
// Check if this is a valid file to open in EFI
-
- // What to do with symlinks? They're nonsense when absolute but may
- // be useful when they're relative. Right now, they're ignored, since they
- // bring a lot of trouble for something that's not as useful in our case.
- // If you want to link, use hard links.
-
if (!Ext4FileIsOpenable (File)) {
Ext4CloseInternal (File);
// This looks like an /okay/ status to return.
return EFI_ACCESS_DENIED;
}
+ //
+ // Reading symlink and then trying to follow it
+ //
+ if (Ext4FileIsSymlink (File)) {
+ Partition->Root->SymLoops++;
+ DEBUG ((DEBUG_FS, "[ext4] File %s is symlink, trying to read it\n", PathSegment));
+ Status = Ext4ReadSymlink (Partition, File, &Symlink);
+ if (EFI_ERROR (Status)) {
+ DEBUG ((DEBUG_FS, "[ext4] Error reading %s symlink!\n", PathSegment));
+ return Status;
+ }
+
+ DEBUG ((DEBUG_FS, "[ext4] File %s is linked to %s\n", PathSegment, Symlink));
+ //
+ // Close symlink file
+ //
+ Ext4CloseInternal (File);
+ //
+ // Open linked file by recursive call of Ext4OpenFile
+ //
+ Status = Ext4OpenInternal (FoundFile, Current, Symlink, OpenMode, Attributes);
+ FreePool (Symlink);
+ if (EFI_ERROR (Status)) {
+ DEBUG ((DEBUG_FS, "[ext4] Error opening linked file %s\n", Symlink));
+ return Status;
+ }
+
+ //
+ // Set File to newly opened
+ //
+ File = *FoundFile;
+ }
+
if (Level != 0) {
// Careful not to close the base directory
Ext4CloseInternal (Current);
@@ -273,12 +325,75 @@ Ext4Open (
return EFI_ACCESS_DENIED;
}
- *NewHandle = &Current->Protocol;
+ *FoundFile = Current;
DEBUG ((DEBUG_FS, "[ext4] Opened filename %s\n", Current->Dentry->Name));
return EFI_SUCCESS;
}
+/**
+ Opens a new file relative to the source file's location.
+ @param[in] This A pointer to the EFI_FILE_PROTOCOL instance that is the file
+ handle to the source location. This would typically be an open
+ handle to a directory.
+ @param[out] NewHandle A pointer to the location to return the opened handle for the new
+ file.
+ @param[in] FileName The Null-terminated string of the name of the file to be opened.
+ The file name may contain the following path modifiers: "\", ".",
+ and "..".
+ @param[in] OpenMode The mode to open the file. The only valid combinations that the
+ file may be opened with are: Read, Read/Write, or Create/Read/Write.
+ @param[in] Attributes Only valid for EFI_FILE_MODE_CREATE, in which case these are the
+ attribute bits for the newly created file.
+ @retval EFI_SUCCESS The file was opened.
+ @retval EFI_NOT_FOUND The specified file could not be found on the device.
+ @retval EFI_NO_MEDIA The device has no medium.
+ @retval EFI_MEDIA_CHANGED The device has a different medium in it or the medium is no
+ longer supported.
+ @retval EFI_DEVICE_ERROR The device reported an error.
+ @retval EFI_VOLUME_CORRUPTED The file system structures are corrupted.
+ @retval EFI_WRITE_PROTECTED An attempt was made to create a file, or open a file for write
+ when the media is write-protected.
+ @retval EFI_ACCESS_DENIED The service denied access to the file.
+ @retval EFI_OUT_OF_RESOURCES Not enough resources were available to open the file.
+ @retval EFI_VOLUME_FULL The volume is full.
+**/
+EFI_STATUS
+EFIAPI
+Ext4Open (
+ IN EFI_FILE_PROTOCOL *This,
+ OUT EFI_FILE_PROTOCOL **NewHandle,
+ IN CHAR16 *FileName,
+ IN UINT64 OpenMode,
+ IN UINT64 Attributes
+ )
+{
+ EFI_STATUS Status;
+ EXT4_FILE *FoundFile;
+ EXT4_FILE *Source;
+
+ Source = (EXT4_FILE *)This;
+
+ //
+ // Reset SymLoops counter
+ //
+ Source->Partition->Root->SymLoops = 0;
+
+ Status = Ext4OpenInternal (
+ &FoundFile,
+ Source,
+ FileName,
+ OpenMode,
+ Attributes
+ );
+
+ if (!EFI_ERROR (Status)) {
+ *NewHandle = &FoundFile->Protocol;
+ }
+
+ return Status;
+}
+
/**
Closes a specified file handle.
@@ -588,7 +703,7 @@ Ext4GetVolumeName (
// s_volume_name is only valid on dynamic revision; old filesystems don't support this
if (Partition->SuperBlock.s_rev_level == EXT4_DYNAMIC_REV) {
- CopyMem (TempVolName, (CONST CHAR8 *)Partition->SuperBlock.s_volume_name, 16);
+ CopyMem (TempVolName, Partition->SuperBlock.s_volume_name, 16);
TempVolName[16] = '\0';
Status = UTF8StrToUCS2 (TempVolName, &VolumeName);
@@ -754,12 +869,14 @@ Ext4GetInfo (
OUT VOID *Buffer
)
{
+ EXT4_FILE *File;
EXT4_PARTITION *Partition;
- Partition = ((EXT4_FILE *)This)->Partition;
+ File = (EXT4_FILE *)This;
+ Partition = File->Partition;
if (CompareGuid (InformationType, &gEfiFileInfoGuid)) {
- return Ext4GetFileInfo ((EXT4_FILE *)This, Buffer, BufferSize);
+ return Ext4GetFileInfo (File, Buffer, BufferSize);
}
if (CompareGuid (InformationType, &gEfiFileSystemInfoGuid)) {
@@ -870,12 +987,12 @@ Ext4SetInfo (
)
{
EXT4_FILE *File;
- EXT4_PARTITION *Part;
+ EXT4_PARTITION *Partition;
- File = (EXT4_FILE *)This;
- Part = File->Partition;
+ File = (EXT4_FILE *)This;
+ Partition = File->Partition;
- if (Part->ReadOnly) {
+ if (Partition->ReadOnly) {
return EFI_WRITE_PROTECTED;
}
diff --git a/Features/Ext4Pkg/Ext4Dxe/Inode.c b/Features/Ext4Pkg/Ext4Dxe/Inode.c
index 7f8be2f02643..5ccb4d2bfc42 100644
--- a/Features/Ext4Pkg/Ext4Dxe/Inode.c
+++ b/Features/Ext4Pkg/Ext4Dxe/Inode.c
@@ -255,6 +255,21 @@ Ext4FileIsDir (
return (File->Inode->i_mode & EXT4_INO_TYPE_DIR) == EXT4_INO_TYPE_DIR;
}
+/**
+ Checks if a file is a symlink.
+
+ @param[in] File Pointer to the opened file.
+
+ @return BOOLEAN Whether file is a symlink
+**/
+BOOLEAN
+Ext4FileIsSymlink (
+ IN CONST EXT4_FILE *File
+ )
+{
+ return (File->Inode->i_mode & EXT4_INO_TYPE_SYMLINK) == EXT4_INO_TYPE_SYMLINK;
+}
+
/**
Checks if a file is a regular file.
@param[in] File Pointer to the opened file.
diff --git a/Features/Ext4Pkg/Ext4Dxe/Symlink.c b/Features/Ext4Pkg/Ext4Dxe/Symlink.c
new file mode 100644
index 000000000000..0905417ffb88
--- /dev/null
+++ b/Features/Ext4Pkg/Ext4Dxe/Symlink.c
@@ -0,0 +1,261 @@
+/** @file
+ Symbolic links routines
+
+ Copyright (c) 2022 Savva Mitrofanov All rights reserved.
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include "Ext4Dxe.h"
+
+/**
+ Detects if a symlink is a fast symlink.
+
+ @param[in] File Pointer to the opened file.
+
+ @return BOOLEAN Whether symlink is a fast symlink
+**/
+STATIC
+BOOLEAN
+Ext4SymlinkIsFastSymlink (
+ IN CONST EXT4_FILE *File
+ )
+{
+ //
+ // Detection logic of the fast-symlink splits into two behaviors - old and new.
+ // The old behavior is based on comparing the extended attribute blocks
+ // with the inode's i_blocks, and if it's zero we know the inode isn't storing
+ // the link in filesystem blocks, so we look to the inode->i_data.
+ // The new behavior is apparently needed only with the large EA inode feature.
+ // In this case we check that inode size less than maximum fast symlink size.
+ // So, we revert to the old behavior if the large EA inode feature is not set.
+ //
+ UINT32 FileAcl;
+ UINT32 ExtAttrBlocks;
+
+ if ((File->Inode->i_flags & EXT4_EA_INODE_FL) == 0) {
+ FileAcl = File->Inode->i_file_acl;
+ if (EXT4_IS_64_BIT (File->Partition)) {
+ //
+ // We don't care about final value, we are just checking for any bit is set
+ // so, thats why we neglect LShiftU64(.., 32)
+ //
+ FileAcl |= File->Inode->i_osd2.data_linux.l_i_file_acl_high;
+ }
+
+ ExtAttrBlocks = FileAcl != 0 ? (File->Partition->BlockSize >> 9) : 0;
+
+ return File->Inode->i_blocks == ExtAttrBlocks;
+ }
+
+ return EXT4_INODE_SIZE (File->Inode) <= EXT4_FAST_SYMLINK_MAX_SIZE;
+}
+
+/**
+ Reads a fast symlink file.
+
+ @param[in] Partition Pointer to the ext4 partition.
+ @param[in] File Pointer to the open symlink file.
+ @param[out] AsciiSymlink Pointer to the output ascii symlink string.
+ @param[out] AsciiSymlinkSize Pointer to the output ascii symlink string length.
+
+ @retval EFI_SUCCESS Fast symlink was read.
+ @retval EFI_OUT_OF_RESOURCES Memory allocation error.
+**/
+STATIC
+EFI_STATUS
+Ext4ReadFastSymlink (
+ IN EXT4_PARTITION *Partition,
+ IN EXT4_FILE *File,
+ OUT CHAR8 **AsciiSymlink,
+ OUT UINT32 *AsciiSymlinkSize
+ )
+{
+ UINT32 SymlinkSize;
+ CHAR8 *AsciiSymlinkTmp;
+
+ //
+ // Fast-symlink's EXT4_INODE_SIZE is not necessarily validated when we checked it in
+ // Ext4SymlinkIsFastSymlink(), so truncate if necessary.
+ //
+ SymlinkSize = (UINT32)MIN (EXT4_INODE_SIZE (File->Inode), EXT4_FAST_SYMLINK_MAX_SIZE);
+
+ AsciiSymlinkTmp = AllocatePool (SymlinkSize + 1);
+ if (AsciiSymlinkTmp == NULL) {
+ DEBUG ((DEBUG_ERROR, "[ext4] Failed to allocate symlink ascii string buffer\n"));
+ return EFI_OUT_OF_RESOURCES;
+ }
+
+ CopyMem (AsciiSymlinkTmp, File->Inode->i_data, SymlinkSize);
+
+ //
+ // Add null-terminator
+ //
+ AsciiSymlinkTmp[SymlinkSize] = '\0';
+
+ *AsciiSymlink = AsciiSymlinkTmp;
+ *AsciiSymlinkSize = SymlinkSize + 1;
+
+ return EFI_SUCCESS;
+}
+
+/**
+ Reads a slow symlink file.
+
+ @param[in] Partition Pointer to the ext4 partition.
+ @param[in] File Pointer to the open symlink file.
+ @param[out] AsciiSymlink Pointer to the output ascii symlink string.
+ @param[out] AsciiSymlinkSize Pointer to the output ascii symlink string length.
+
+ @retval EFI_SUCCESS Slow symlink was read.
+ @retval EFI_OUT_OF_RESOURCES Memory allocation error.
+ @retval EFI_INVALID_PARAMETER Slow symlink path has incorrect length
+ @retval EFI_VOLUME_CORRUPTED Symlink read block size differ from inode value
+**/
+STATIC
+EFI_STATUS
+Ext4ReadSlowSymlink (
+ IN EXT4_PARTITION *Partition,
+ IN EXT4_FILE *File,
+ OUT CHAR8 **AsciiSymlink,
+ OUT UINT32 *AsciiSymlinkSize
+ )
+{
+ EFI_STATUS Status;
+ CHAR8 *SymlinkTmp;
+ UINT64 SymlinkSizeTmp;
+ UINT32 SymlinkAllocateSize;
+ UINTN ReadSize;
+
+ SymlinkSizeTmp = EXT4_INODE_SIZE (File->Inode);
+
+ //
+ // Allocate EXT4_INODE_SIZE + 1
+ //
+ if (SymlinkSizeTmp >= EXT4_EFI_PATH_MAX) {
+ DEBUG ((
+ DEBUG_WARN,
+ "[ext4] Warn: symlink path maximum length was hit!\n"
+ ));
+ return EFI_INVALID_PARAMETER;
+ }
+
+ SymlinkAllocateSize = (UINT32)SymlinkSizeTmp + 1;
+
+ SymlinkTmp = AllocatePool (SymlinkAllocateSize);
+ if (SymlinkTmp == NULL) {
+ DEBUG ((DEBUG_FS, "[ext4] Failed to allocate symlink ascii string buffer\n"));
+ return EFI_OUT_OF_RESOURCES;
+ }
+
+ ReadSize = (UINTN)SymlinkSizeTmp;
+ Status = Ext4Read (Partition, File, SymlinkTmp, File->Position, &ReadSize);
+ if (EFI_ERROR (Status)) {
+ DEBUG ((DEBUG_FS, "[ext4] Failed to read symlink from blocks with status %r\n", Status));
+ FreePool (SymlinkTmp);
+ return Status;
+ }
+
+ //
+ // Add null-terminator
+ //
+ SymlinkTmp[SymlinkSizeTmp] = '\0';
+
+ if (SymlinkSizeTmp != ReadSize) {
+ DEBUG ((
+ DEBUG_FS,
+ "[ext4] Error! The size of the read block doesn't match the value from the inode!\n"
+ ));
+ return EFI_VOLUME_CORRUPTED;
+ }
+
+ *AsciiSymlinkSize = SymlinkAllocateSize;
+ *AsciiSymlink = SymlinkTmp;
+
+ return EFI_SUCCESS;
+}
+
+/**
+ Reads a symlink file.
+
+ @param[in] Partition Pointer to the ext4 partition.
+ @param[in] File Pointer to the open symlink file.
+ @param[out] Symlink Pointer to the output unicode symlink string.
+
+ @retval EFI_SUCCESS Symlink was read.
+ @retval EFI_ACCESS_DENIED Symlink is encrypted.
+ @retval EFI_OUT_OF_RESOURCES Memory allocation error.
+ @retval EFI_INVALID_PARAMETER Symlink path has incorrect length
+ @retval EFI_VOLUME_CORRUPTED Symlink read block size differ from inode value
+**/
+EFI_STATUS
+Ext4ReadSymlink (
+ IN EXT4_PARTITION *Partition,
+ IN EXT4_FILE *File,
+ OUT CHAR16 **Symlink
+ )
+{
+ EFI_STATUS Status;
+ CHAR8 *SymlinkTmp;
+ UINT32 SymlinkSize;
+ CHAR16 *Symlink16Tmp;
+ CHAR16 *Needle;
+
+ //
+ // Assume that we alread read Inode via Ext4ReadInode
+ // Skip reading, just check encryption flag
+ //
+ if ((File->Inode->i_flags & EXT4_ENCRYPT_FL) != 0) {
+ DEBUG ((DEBUG_WARN, "[ext4] Warn: symlink is encrypted\n"));
+ return EFI_ACCESS_DENIED;
+ }
+
+ if (Ext4SymlinkIsFastSymlink (File)) {
+ Status = Ext4ReadFastSymlink (Partition, File, &SymlinkTmp, &SymlinkSize);
+ } else {
+ Status = Ext4ReadSlowSymlink (Partition, File, &SymlinkTmp, &SymlinkSize);
+ }
+
+ if (EFI_ERROR (Status)) {
+ DEBUG ((DEBUG_FS, "[ext4] Symlink read error with Status %r\n", Status));
+ return Status;
+ }
+
+ Symlink16Tmp = AllocatePool (SymlinkSize * sizeof (CHAR16));
+ if (Symlink16Tmp == NULL) {
+ DEBUG ((DEBUG_FS, "[ext4] Failed to allocate symlink unicode string buffer\n"));
+ FreePool (SymlinkTmp);
+ return EFI_OUT_OF_RESOURCES;
+ }
+
+ Status = AsciiStrToUnicodeStrS (
+ SymlinkTmp,
+ Symlink16Tmp,
+ SymlinkSize
+ );
+
+ FreePool (SymlinkTmp);
+
+ if (EFI_ERROR (Status)) {
+ DEBUG ((
+ DEBUG_FS,
+ "[ext4] Failed to convert ascii symlink to unicode with Status %r\n",
+ Status
+ ));
+ FreePool (Symlink16Tmp);
+ FreePool (SymlinkTmp);
+ return Status;
+ }
+
+ //
+ // Convert to UEFI slashes
+ //
+ for (Needle = Symlink16Tmp; *Needle != L'\0'; Needle++) {
+ if (*Needle == L'/') {
+ *Needle = L'\\';
+ }
+ }
+
+ *Symlink = Symlink16Tmp;
+
+ return Status;
+}
--
2.37.3
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