[edk2-devel] [edk2-platforms][PATCH v4 1/2] Ext4Pkg: Add symbolic links support
Savva Mitrofanov
savvamtr at gmail.com
Wed Sep 7 13:53:58 UTC 2022
Hi Pedro,
Thank you for your code-review. I answer to comments inline too.
> On 30 Aug 2022, at 04:12, Pedro Falcato <pedro.falcato at gmail.com> wrote:
>
> Hi Savva,
>
> Sorry for the huge delay. Comments inline.
>
> On Thu, Jul 28, 2022 at 4:26 PM Savva Mitrofanov <savvamtr at gmail.com <mailto:savvamtr at gmail.com>> wrote:
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3677 <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 at posteo.de <mailto:mhaeuser at posteo.de>>
> Cc: Pedro Falcato <pedro.falcato at gmail.com <mailto:pedro.falcato at gmail.com>>
> Cc: Vitaly Cheptsov <vit9696 at protonmail.com <mailto:vit9696 at protonmail.com>>
> Signed-off-by: Savva Mitrofanov <savvamtr at gmail.com <mailto:savvamtr at gmail.com>>
> ---
> Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h | 13 +-
> Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h | 98 +++++-
> Features/Ext4Pkg/Ext4Dxe/File.c | 359 ++++++++++++++++++--
> Features/Ext4Pkg/Ext4Dxe/Inode.c | 53 +++
> 4 files changed, 485 insertions(+), 38 deletions(-)
>
> diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h b/Features/Ext4Pkg/Ext4Dxe/Ext4Disk.h
> index a55cd2fa68ad..a73e3f8622f1 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 128
>
> diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
> index b1508482b0a7..c1df9d1149e4 100644
> --- a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
> +++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
> @@ -31,7 +31,9 @@
>
> #include "Ext4Disk.h"
>
> +#define SYMLOOP_MAX 8
> I'm scared that this may not be enough. Could we use 40 here as Linux does?
As we discussed, the limit equal 8 should be compatible for booting all modern operation systems using this fs driver.
In this recursion-based symlink implementation it is a bit dangerous due to possible exceed of stack size. So we
decided keep this limit until we are do the lookup logic like namei.
> #define EXT4_NAME_MAX 255
> +#define EFI_PATH_MAX 4096
> Don't use EFI_* in Ext4Dxe code, so prefix this with EXT4_ instead maybe?
As a result of consensus, it was decided to use EXT4_EFI_PATH_MAX.
>
> #define EXT4_DRIVER_VERSION 0x0000
>
> @@ -324,11 +326,11 @@ 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 +370,7 @@ struct _Ext4File {
>
> UINT64 OpenMode;
> UINT64 Position;
> + UINT32 SymLoops;
>
> EXT4_PARTITION *Partition;
>
> @@ -497,6 +500,45 @@ 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,
> First IN parameters, then OUT parameters.
Due to lack of strict order conventions on procedure parameters, I consider to keep it unchanged, because all important C APIs have
destination first.
>
> + IN EXT4_FILE *Source,
> + IN CHAR16 *FileName,
> + IN UINT64 OpenMode,
> + IN UINT64 Attributes
> + );
> +
> /**
> Closes a file.
>
> @@ -774,6 +816,30 @@ 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
> + );
> +
> +/**
> + Detects if a symlink is a fast symlink.
> +
> + @param[in] File Pointer to the opened file.
> +
> + @return BOOLEAN Whether symlink is a fast symlink
> +**/
> +BOOLEAN
> +Ext4SymlinkIsFastSymlink (
> + IN CONST EXT4_FILE *File
> + );
> Does this need to be in Ext4Dxe.h? This is pretty symlink specific.
I agree with you, in the next patch I'll separate symlink-related functions into independent file.
> +
> /**
> Checks if a file is a regular file.
> @param[in] File Pointer to the opened file.
> @@ -797,7 +863,7 @@ 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 >= \
> @@ -935,6 +1001,26 @@ Ext4ReadDir (
> IN OUT UINTN *OutLength
> );
>
> +/**
> + 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
> + );
> +
> /**
> Initialises the (empty) extents map, that will work as a cache of extents.
>
> diff --git a/Features/Ext4Pkg/Ext4Dxe/File.c b/Features/Ext4Pkg/Ext4Dxe/File.c
> index ff1746d5640a..ae9230d6422b 100644
> --- a/Features/Ext4Pkg/Ext4Dxe/File.c
> +++ b/Features/Ext4Pkg/Ext4Dxe/File.c
> @@ -134,14 +134,224 @@ Ext4DirCanLookup (
> return (File->Inode->i_mode & EXT4_INO_PERM_EXEC_OWNER) == EXT4_INO_PERM_EXEC_OWNER;
> }
>
> +/**
> + 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.
> + //
> I think the correct solution here is to check if the inode size fits in EXT4_FAST_SYMLINK_MAX_SIZE in Ext4SymlinkIsFastSymlink. Or possibly check it here and error-out (blatant corruption).
> Truncating doesn't seem correct.
The origin problem comes from old filesystems (ext2,ext3) which can have wrong inode size for symlinks. There are two behaviours on detection logic, the old one,
which is suitable for old filesystems is based on checking presence of extended attribute and doesnt have inode size check. So in such case we just additionally truncate it by EXT4_FAST_SYMLINK_MAX_SIZE using MIN macro.
> + SymlinkSize = (UINT32)MIN (EXT4_INODE_SIZE (File->Inode), EXT4_FAST_SYMLINK_MAX_SIZE);
> +
> + AsciiSymlinkTmp = AllocatePool (SymlinkSize + 1);
> + if (AsciiSymlinkTmp == NULL) {
> + DEBUG ((DEBUG_FS, "[ext4] Failed to allocate symlink ascii string buffer\n"));
> Nit: DEBUG_ERROR?
> + 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 > EFI_PATH_MAX - 1) {
> Why is this > EFI_PATH_MAX - 1 and not >= EFI_PATH_MAX? Also, why does the inode size need to be strictly smaller than EFI_PATH_MAX?
Yes, my mistake, I'll correct it in the next patch.
> + DEBUG ((
> + DEBUG_FS,
> Nit: DEBUG_ERROR?
I'm not agree that there we should use DEBUG_ERROR, because it will threats like fatal error, and it can breaks boot process in some configurations, that why I kept DEBUG_FS in this condition. The logic is simple - if something wrong with symlink then just skip it. So, as a result of the discussion, we came to a consensus to replace such places with DEBUG_WARN macros.
> + "[ext4] Error! 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));
> Nit: lowercase "status" in the DEBUG.
> + FreePool (SymlinkTmp);
> + return Status;
> + }
> +
> + File->Position += ReadSize;
> Taking Position into account (here and in the Ext4Read call) seems wrong. Why would the file seek affect the readlink() operation?
Yes, it's pointless there, I'll remove it in the next revision.
> +
> + //
> + // Add null-terminator
> + //
> + SymlinkTmp[SymlinkSizeTmp] = '\0';
> +
> + if (SymlinkSizeTmp != ReadSize) {
> + DEBUG ((
> + DEBUG_FS,
> + "[ext4] Error! The sz of the read block doesn't match the value from the inode!\n"
> Nit: size
> + ));
> + 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_FS, "[ext4] Error, symlink is encrypted\n"));
> Nit: DEBUG_ERROR and "Error: ".
> + 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 = AllocateZeroPool (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
> + );
> +
> + 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;
> +
> + FreePool (SymlinkTmp);
> + return Status;
> +}
> +
> /**
> 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 +375,12 @@ 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 +389,14 @@ 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 +404,11 @@ Ext4Open (
> }
>
> while (FileName[0] != L'\0') {
> + if (Partition->Root->
>
> > 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 +453,45 @@ 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 +515,75 @@ 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;
> Keeping SymLoops in the root FILE seems kind of out of place. My idea here (and this was going to be chained with a bunch of improvements to the path walking logic, which is why I never got around to adding symlink support) was to add a nameidata(see Onyx code, or NetBSD's namei(9) manpage)-like structure, as you would in typical UNIX fashion. You would then do your whole path traversal on that structure, which would keep your path walking state, walked_symlinks, etc.
We will fix it in the future patches, when we will provide namei-like mechanism for proceeding symlinks.
> +
> + Status = Ext4OpenInternal (
> + &FoundFile,
> + Source,
> + FileName,
> + OpenMode,
> + Attributes
> + );
> +
> + if (!EFI_ERROR (Status)) {
> + *NewHandle = &FoundFile->Protocol;
> + }
> +
> + return Status;
> +}
> +
> /**
> Closes a specified file handle.
>
> @@ -588,7 +893,7 @@ 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 +1059,14 @@ 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 +1177,12 @@ 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 831f5946e870..e7a6b3225709 100644
> --- a/Features/Ext4Pkg/Ext4Dxe/Inode.c
> +++ b/Features/Ext4Pkg/Ext4Dxe/Inode.c
> @@ -255,6 +255,59 @@ 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;
> +}
> +
> +/**
> + Detects if a symlink is a fast symlink.
> +
> + @param[in] File Pointer to the opened file.
> +
> + @return BOOLEAN Whether symlink is a fast symlink
> +**/
> +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)) {
> + FileAcl |= LShiftU64 (File->Inode->i_osd2.data_linux.l_i_file_acl_high, 32);
> + }
> +
> + 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;
> +}
> +
> /**
> Checks if a file is a regular file.
> @param[in] File Pointer to the opened file.
> --
> 2.37.1
>
>
>
> --
> Pedro Falcato
All the best!
Savva Mitrofanov
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#93420): https://edk2.groups.io/g/devel/message/93420
Mute This Topic: https://groups.io/mt/92672600/1813853
Group Owner: devel+owner at edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [edk2-devel-archive at redhat.com]
-=-=-=-=-=-=-=-=-=-=-=-
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/edk2-devel-archive/attachments/20220907/740fd3cc/attachment-0001.htm>
More information about the edk2-devel-archive
mailing list