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path: root/fs/smb/client/reparse.c
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2025-01-31cifs: Add support for creating WSL-style symlinksPali Rohár1-12/+53
This change implements support for creating new symlink in WSL-style by Linux cifs client when -o reparse=wsl mount option is specified. WSL-style symlink uses reparse point with tag IO_REPARSE_TAG_LX_SYMLINK and symlink target location is stored in reparse buffer in UTF-8 encoding prefixed by 32-bit flags. Flags bits are unknown, but it was observed that WSL always sets flags to value 0x02000000. Do same in Linux cifs client. New symlinks would be created in WSL-style only in case the mount option -o reparse=wsl is specified, which is not by default. So default CIFS mounts are not affected by this change. Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-01-31cifs: Add support for creating NFS-style symlinksPali Rohár1-8/+39
CIFS client is currently able to parse NFS-style symlinks, but is not able to create them. This functionality is useful when the mounted SMB share is used also by Windows NFS server (on Windows Server 2012 or new). It allows interop of symlinks between SMB share mounted by Linux CIFS client and same export from Windows NFS server mounted by some NFS client. New symlinks would be created in NFS-style only in case the mount option -o reparse=nfs is specified, which is not by default. So default CIFS mounts are not affected by this change. Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-01-31cifs: Add support for creating native Windows socketsPali Rohár1-0/+32
Native Windows sockets created by WinSock on Windows 10 April 2018 Update (version 1803) or Windows Server 2019 (version 1809) or later versions is reparse point with IO_REPARSE_TAG_AF_UNIX tag, with empty reparse point data buffer and without any EAs. Create AF_UNIX sockets in this native format if -o nonativesocket was not specified. This change makes AF_UNIX sockets created by Linux CIFS client compatible with AF_UNIX sockets created by Windows applications on NTFS volumes. Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-01-30cifs: Add mount option -o symlink= for choosing symlink create typePali Rohár1-10/+42
Currently Linux CIFS client creates a new symlink of the first flavor which is allowed by mount options, parsed in this order: -o (no)mfsymlinks, -o (no)sfu, -o (no)unix (+ its aliases) and -o reparse=[type]. Introduce a new mount option -o symlink= for explicitly choosing a symlink flavor. Possible options are: -o symlink=default - The default behavior, like before this change. -o symlink=none - Disallow creating a new symlinks -o symlink=native - Create as native SMB symlink reparse point -o symlink=unix - Create via SMB1 unix extension command -o symlink=mfsymlinks - Create as regular file of mfsymlinks format -o symlink=sfu - Create as regular system file of SFU format -o symlink=nfs - Create as NFS reparse point -o symlink=wsl - Create as WSL reparse point So for example specifying -o sfu,mfsymlinks,symlink=native will allow to parse symlinks also of SFU and mfsymlinks types (which are disabled by default unless mount option is explicitly specified), but new symlinks will be created under native SMB type (which parsing is always enabled). Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-01-30cifs: Fix creating and resolving absolute NT-style symlinksPali Rohár1-18/+249
If the SMB symlink is stored on NT server in absolute form then it points to the NT object hierarchy, which is different from POSIX one and needs some conversion / mapping. To make interoperability with Windows SMB server and WSL subsystem, reuse its logic of mapping between NT paths and POSIX paths into Linux SMB client. WSL subsystem on Windows uses for -t drvfs mount option -o symlinkroot= which specifies the POSIX path where are expected to be mounted lowercase Windows drive letters (without colon). Do same for Linux SMB client and add a new mount option -o symlinkroot= which mimics the drvfs mount option of the same name. It specifies where in the Linux VFS hierarchy is the root of the DOS / Windows drive letters, and translates between absolute NT-style symlinks and absolute Linux VFS symlinks. Default value of symlinkroot is "/mnt", same what is using WSL. Note that DOS / Windows drive letter symlinks are just subset of all possible NT-style symlinks. Drive letters live in NT subtree \??\ and important details about NT paths and object hierarchy are in the comments in this change. When symlink target location from non-POSIX SMB server is in absolute form (indicated by absence of SYMLINK_FLAG_RELATIVE) then it is converted to Linux absolute symlink according to symlinkroot configuration. And when creating a new symlink on non-POSIX SMB server in absolute form then Linux absolute target is converted to NT-style according to symlinkroot configuration. When SMB server is POSIX, then this change does not affect neither reading target location of symlink, nor creating a new symlink. It is expected that POSIX SMB server works with POSIX paths where the absolute root is /. This change improves interoperability of absolute SMB symlinks with Windows SMB servers. Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-01-30cifs: Rename struct reparse_posix_data to reparse_nfs_data_buffer and move ↵Pali Rohár1-6/+6
to common/smb2pdu.h Function parse_reparse_posix() parses NFS-style reparse points, which are used only by Windows NFS server since Windows Server 2012 version. This style is not understood by Microsoft POSIX/Interix/SFU/SUA subsystems. So make it clear that parse_reparse_posix() function and reparse_posix_data structure are not POSIX general, but rather NFS specific. All reparse buffer structures are defined in common/smb2pdu.h and have _buffer suffix. So move struct reparse_posix_data from client/cifspdu.h to common/smb2pdu.h and rename it to reparse_nfs_data_buffer for consistency. Note that also SMB specification in [MS-FSCC] document, section 2.1.2.6 defines it under name "Network File System (NFS) Reparse Data Buffer". So use this name for consistency. Having this structure in common/smb2pdu.h can be useful for ksmbd server code as NFS-style reparse points is the preferred way for implementing support for special files. Signed-off-by: Pali Rohár <pali@kernel.org> Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> Reviewed-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-01-30cifs: Remove struct reparse_posix_data from struct cifs_open_info_dataPali Rohár1-3/+2
Linux SMB client already supports more reparse point types but only the reparse_posix_data is defined in union of struct cifs_open_info_data. This union is currently used as implicit casting between point types. With this code style, it hides information that union is used for pointer casting, and just in mknod_nfs() and posix_reparse_to_fattr() functions. Other reparse point buffers do not use this kind of casting. So remove reparse_posix_data from reparse part of struct cifs_open_info_data and for all cases of reparse buffer use just struct reparse_data_buffer *buf. Signed-off-by: Pali Rohár <pali@kernel.org> Reviewed-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-01-30cifs: Remove unicode parameter from parse_reparse_point() functionPali Rohár1-14/+11
This parameter is always true, so remove it and also remove dead code which is never called (for all false code paths). Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2025-01-30cifs: Validate EAs for WSL reparse pointsPali Rohár1-4/+18
Major and minor numbers for char and block devices are mandatory for stat. So check that the WSL EA $LXDEV is present for WSL CHR and BLK reparse points. WSL reparse point tag determinate type of the file. But file type is present also in the WSL EA $LXMOD. So check that both file types are same. Fixes: 78e26bec4d6d ("smb: client: parse uid, gid, mode and dev from WSL reparse points") Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-12-10smb3: fix compiler warning in reparse codeSteve French1-1/+1
utf8s_to_utf16s() specifies pwcs as a wchar_t pointer (whether big endian or little endian is passed in as an additional parm), so to remove a distracting compile warning it needs to be cast as (wchar_t *) in parse_reparse_wsl_symlink() as done by other callers. Fixes: 06a7adf318a3 ("cifs: Add support for parsing WSL-style symlinks") Reviewed-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-12-05fs/smb/client: Implement new SMB3 POSIX typeRalph Boehme1-32/+52
Fixes special files against current Samba. On the Samba server: insgesamt 20 131958 brw-r--r-- 1 root root 0, 0 15. Nov 12:04 blockdev 131965 crw-r--r-- 1 root root 1, 1 15. Nov 12:04 chardev 131966 prw-r--r-- 1 samba samba 0 15. Nov 12:05 fifo 131953 -rw-rwxrw-+ 2 samba samba 4 18. Nov 11:37 file 131953 -rw-rwxrw-+ 2 samba samba 4 18. Nov 11:37 hardlink 131957 lrwxrwxrwx 1 samba samba 4 15. Nov 12:03 symlink -> file 131954 -rwxrwxr-x+ 1 samba samba 0 18. Nov 15:28 symlinkoversmb Before: ls: cannot access '/mnt/smb3unix/posix/blockdev': No data available ls: cannot access '/mnt/smb3unix/posix/chardev': No data available ls: cannot access '/mnt/smb3unix/posix/symlinkoversmb': No data available ls: cannot access '/mnt/smb3unix/posix/fifo': No data available ls: cannot access '/mnt/smb3unix/posix/symlink': No data available total 16 ? -????????? ? ? ? ? ? blockdev ? -????????? ? ? ? ? ? chardev ? -????????? ? ? ? ? ? fifo 131953 -rw-rwxrw- 2 root samba 4 Nov 18 11:37 file 131953 -rw-rwxrw- 2 root samba 4 Nov 18 11:37 hardlink ? -????????? ? ? ? ? ? symlink ? -????????? ? ? ? ? ? symlinkoversmb After: insgesamt 21 131958 brw-r--r-- 1 root root 0, 0 15. Nov 12:04 blockdev 131965 crw-r--r-- 1 root root 1, 1 15. Nov 12:04 chardev 131966 prw-r--r-- 1 root samba 0 15. Nov 12:05 fifo 131953 -rw-rwxrw- 2 root samba 4 18. Nov 11:37 file 131953 -rw-rwxrw- 2 root samba 4 18. Nov 11:37 hardlink 131957 lrwxrwxrwx 1 root samba 4 15. Nov 12:03 symlink -> file 131954 lrwxrwxr-x 1 root samba 23 18. Nov 15:28 symlinkoversmb -> mnt/smb3unix/posix/file Cc: stable@vger.kernel.org Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> Signed-off-by: Ralph Boehme <slow@samba.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-11-25cifs: Validate content of WSL reparse point buffersPali Rohár1-0/+5
WSL socket, fifo, char and block devices have empty reparse buffer. Validate the length of the reparse buffer. Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-11-25cifs: Improve guard for excluding $LXDEV xattrPali Rohár1-2/+2
$LXDEV xattr is for storing block/char device's major and minor number. Change guard which excludes storing $LXDEV xattr to explicitly filter everything except block and char device. Current guard is opposite, which is currently correct but is less-safe. This change is required for adding support for creating WSL-style symlinks as symlinks also do not use device's major and minor numbers. Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-11-25cifs: Add support for parsing WSL-style symlinksPali Rohár1-0/+49
Linux CIFS client currently does not implement readlink() for WSL-style symlinks. It is only able to detect that file is of WSL-style symlink, but is not able to read target symlink location. Add this missing functionality and implement support for parsing content of WSL-style symlink. The important note is that symlink target location stored for WSL symlink reparse point (IO_REPARSE_TAG_LX_SYMLINK) is in UTF-8 encoding instead of UTF-16 (which is used in whole SMB protocol and also in all other symlink styles). So for proper locale/cp support it is needed to do conversion from UTF-8 to local_nls. Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-11-25cifs: Validate content of native symlinkPali Rohár1-0/+19
Check that path buffer has correct length (it is non-zero and in UNICODE mode it has even number of bytes) and check that buffer does not contain null character (UTF-16 null codepoint in UNICODE mode or null byte in non-unicode mode) because Linux cannot process symlink with null byte. Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-11-25cifs: Fix parsing native symlinks relative to the exportPali Rohár1-12/+78
SMB symlink which has SYMLINK_FLAG_RELATIVE set is relative (as opposite of the absolute) and it can be relative either to the current directory (where is the symlink stored) or relative to the top level export path. To what it is relative depends on the first character of the symlink target path. If the first character is path separator then symlink is relative to the export, otherwise to the current directory. Linux (and generally POSIX systems) supports only symlink paths relative to the current directory where is symlink stored. Currently if Linux SMB client reads relative SMB symlink with first character as path separator (slash), it let as is. Which means that Linux interpret it as absolute symlink pointing from the root (/). But this location is different than the top level directory of SMB export (unless SMB export was mounted to the root) and thefore SMB symlinks relative to the export are interpreted wrongly by Linux SMB client. Fix this problem. As Linux does not have equivalent of the path relative to the top of the mount point, convert such symlink target path relative to the current directory. Do this by prepending "../" pattern N times before the SMB target path, where N is the number of path separators found in SMB symlink path. So for example, if SMB share is mounted to Linux path /mnt/share/, symlink is stored in file /mnt/share/test/folder1/symlink (so SMB symlink path is test\folder1\symlink) and SMB symlink target points to \test\folder2\file, then convert symlink target path to Linux path ../../test/folder2/file. Deduplicate code for parsing SMB symlinks in native form from functions smb2_parse_symlink_response() and parse_reparse_native_symlink() into new function smb2_parse_native_symlink() and pass into this new function a new full_path parameter from callers, which specify SMB full path where is symlink stored. This change fixes resolving of the native Windows symlinks relative to the top level directory of the SMB share. Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-11-21smb: client: handle max length for SMB symlinksPaulo Alcantara1-1/+4
We can't use PATH_MAX for SMB symlinks because (1) Windows Server will fail FSCTL_SET_REPARSE_POINT with STATUS_IO_REPARSE_DATA_INVALID when input buffer is larger than 16K, as specified in MS-FSA 2.1.5.10.37. (2) The client won't be able to parse large SMB responses that includes SMB symlink path within SMB2_CREATE or SMB2_IOCTL responses. Fix this by defining a maximum length value (4060) for SMB symlinks that both client and server can handle. Cc: David Howells <dhowells@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-10-07cifs: Improve creating native symlinks pointing to directoryPali Rohár1-3/+161
SMB protocol for native symlinks distinguish between symlink to directory and symlink to file. These two symlink types cannot be exchanged, which means that symlink of file type pointing to directory cannot be resolved at all (and vice-versa). Windows follows this rule for local filesystems (NTFS) and also for SMB. Linux SMB client currenly creates all native symlinks of file type. Which means that Windows (and some other SMB clients) cannot resolve symlinks pointing to directory created by Linux SMB client. As Linux system does not distinguish between directory and file symlinks, its API does not provide enough information for Linux SMB client during creating of native symlinks. Add some heuristic into the Linux SMB client for choosing the correct symlink type during symlink creation. Check if the symlink target location ends with slash, or last path component is dot or dot-dot, and check if the target location on SMB share exists and is a directory. If at least one condition is truth then create a new SMB symlink of directory type. Otherwise create it as file type symlink. This change improves interoperability with Windows systems. Windows systems would be able to resolve more SMB symlinks created by Linux SMB client which points to existing directory. Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-10-03cifs: Do not convert delimiter when parsing NFS-style symlinksPali Rohár1-1/+0
NFS-style symlinks have target location always stored in NFS/UNIX form where backslash means the real UNIX backslash and not the SMB path separator. So do not mangle slash and backslash content of NFS-style symlink during readlink() syscall as it is already in the correct Linux form. This fixes interoperability of NFS-style symlinks with backslashes created by Linux NFS3 client throw Windows NFS server and retrieved by Linux SMB client throw Windows SMB server, where both Windows servers exports the same directory. Fixes: d5ecebc4900d ("smb3: Allow query of symlinks stored as reparse points") Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-10-03cifs: Validate content of NFS reparse point bufferPali Rohár1-0/+23
Symlink target location stored in DataBuffer is encoded in UTF-16. So check that symlink DataBuffer length is non-zero and even number. And check that DataBuffer does not contain UTF-16 null codepoint because Linux cannot process symlink with null byte. DataBuffer for char and block devices is 8 bytes long as it contains two 32-bit numbers (major and minor). Add check for this. DataBuffer buffer for sockets and fifos zero-length. Add checks for this. Signed-off-by: Pali Rohár <pali@kernel.org> Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-10-03cifs: Fix buffer overflow when parsing NFS reparse pointsPali Rohár1-1/+14
ReparseDataLength is sum of the InodeType size and DataBuffer size. So to get DataBuffer size it is needed to subtract InodeType's size from ReparseDataLength. Function cifs_strndup_from_utf16() is currentlly accessing buf->DataBuffer at position after the end of the buffer because it does not subtract InodeType size from the length. Fix this problem and correctly subtract variable len. Member InodeType is present only when reparse buffer is large enough. Check for ReparseDataLength before accessing InodeType to prevent another invalid memory access. Major and minor rdev values are present also only when reparse buffer is large enough. Check for reparse buffer size before calling reparse_mkdev(). Fixes: d5ecebc4900d ("smb3: Allow query of symlinks stored as reparse points") Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-09-25smb: client: fix parsing of device numbersPaulo Alcantara1-3/+3
Report correct major and minor numbers from special files created with NFS reparse points. Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-09-25smb: client: set correct device number on nfs reparse pointsPaulo Alcantara1-2/+2
Fix major and minor numbers set on special files created with NFS reparse points. Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-08-22smb: client: ignore unhandled reparse tagsPaulo Alcantara1-4/+7
Just ignore reparse points that the client can't parse rather than bailing out and not opening the file or directory. Reported-by: Marc <1marc1@gmail.com> Closes: https://lore.kernel.org/r/CAMHwNVv-B+Q6wa0FEXrAuzdchzcJRsPKDDRrNaYZJd6X-+iJzw@mail.gmail.com Fixes: 539aad7f14da ("smb: client: introduce ->parse_reparse_point()") Tested-by: Anthony Nandaa (Microsoft) <profnandaa@gmail.com> Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-08-02smb: client: handle lack of FSCTL_GET_REPARSE_POINT supportPaulo Alcantara1-0/+4
As per MS-FSA 2.1.5.10.14, support for FSCTL_GET_REPARSE_POINT is optional and if the server doesn't support it, STATUS_INVALID_DEVICE_REQUEST must be returned for the operation. If we find files with reparse points and we can't read them due to lack of client or server support, just ignore it and then treat them as regular files or junctions. Fixes: 5f71ebc41294 ("smb: client: parse reparse point flag in create response") Reported-by: Sebastian Steinbeisser <Sebastian.Steinbeisser@lrz.de> Tested-by: Sebastian Steinbeisser <Sebastian.Steinbeisser@lrz.de> Acked-by: Tom Talpey <tom@talpey.com> Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-03-11smb: client: set correct d_type for reparse DFS/DFSR and mount pointPaulo Alcantara1-7/+9
Set correct dirent->d_type for IO_REPARSE_TAG_DFS{,R} and IO_REPARSE_TAG_MOUNT_POINT reparse points. Signed-off-by: Paulo Alcantara <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-03-11smb: client: parse uid, gid, mode and dev from WSL reparse pointsPaulo Alcantara1-14/+64
Parse the extended attributes from WSL reparse points to correctly report uid, gid mode and dev from ther instantiated inodes. Signed-off-by: Paulo Alcantara <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-03-11smb: client: introduce SMB2_OP_QUERY_WSL_EAPaulo Alcantara1-5/+5
Add a new command to smb2_compound_op() for querying WSL extended attributes from reparse points. Signed-off-by: Paulo Alcantara <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-03-11smb: client: Fix a NULL vs IS_ERR() check in wsl_set_xattrs()Dan Carpenter1-1/+1
This was intended to be an IS_ERR() check. The ea_create_context() function doesn't return NULL. Fixes: 1eab17fe485c ("smb: client: add support for WSL reparse points") Reviewed-by: Paulo Alcantara <pc@manguebit.com> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-03-11smb: client: add support for WSL reparse pointsPaulo Alcantara1-5/+165
Add support for creating special files via WSL reparse points when using 'reparse=wsl' mount option. They're faster than NFS reparse points because they don't require extra roundtrips to figure out what ->d_type a specific dirent is as such information is already stored in query dir responses and then making getdents() calls faster. Signed-off-by: Paulo Alcantara <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2024-03-11smb: client: move most of reparse point handling code to common filePaulo Alcantara1-0/+320
In preparation to add support for creating special files also via WSL reparse points in next commits. Signed-off-by: Paulo Alcantara <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>