kernel.git/fs/smb/client/reparse.c, branch linux-6.15.y

smb: client: set symlink type as native for POSIX mounts

2025-08-15T10:17:05Z

commit a967e758f8e9d8ce5ef096743393df5e6e51644b upstream. SMB3.1.1 POSIX mounts require symlinks to be created natively with IO_REPARSE_TAG_SYMLINK reparse point. Cc: linux-cifs@vger.kernel.org Cc: Ralph Boehme Cc: David Howells Cc: Reported-by: Matthew Richardson Closes: https://marc.info/?i=1124e7cd-6a46-40a6-9f44-b7664a66654b@ed.ac.uk Signed-off-by: Paulo Alcantara (Red Hat) Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

smb: client: fix native SMB symlink traversal

2025-07-10T14:08:46Z

[ Upstream commit 3363da82e02f1bddc54faa92ea430c6532e2cd2e ] We've seen customers having shares mounted in paths like /??/C:/ or /??/UNC/foo.example.com/share in order to get their native SMB symlinks successfully followed from different mounts. After commit 12b466eb52d9 ("cifs: Fix creating and resolving absolute NT-style symlinks"), the client would then convert absolute paths from "/??/C:/" to "/mnt/c/" by default. The absolute paths would vary depending on the value of symlinkroot= mount option. Fix this by restoring old behavior of not trying to convert absolute paths by default. Only do this if symlinkroot= was _explicitly_ set. Before patch: $ mount.cifs //w22-fs0/test2 /mnt/1 -o vers=3.1.1,username=xxx,password=yyy $ ls -l /mnt/1/symlink2 lrwxr-xr-x 1 root root 15 Jun 20 14:22 /mnt/1/symlink2 -> /mnt/c/testfile $ mkdir -p /??/C:; echo foo > //??/C:/testfile $ cat /mnt/1/symlink2 cat: /mnt/1/symlink2: No such file or directory After patch: $ mount.cifs //w22-fs0/test2 /mnt/1 -o vers=3.1.1,username=xxx,password=yyy $ ls -l /mnt/1/symlink2 lrwxr-xr-x 1 root root 15 Jun 20 14:22 /mnt/1/symlink2 -> '/??/C:/testfile' $ mkdir -p /??/C:; echo foo > //??/C:/testfile $ cat /mnt/1/symlink2 foo Cc: linux-cifs@vger.kernel.org Reported-by: Pierguido Lambri Cc: David Howells Cc: Stefan Metzmacher Fixes: 12b466eb52d9 ("cifs: Fix creating and resolving absolute NT-style symlinks") Signed-off-by: Paulo Alcantara (Red Hat) Signed-off-by: Steve French Signed-off-by: Sasha Levin

smb: client: fix regression with native SMB symlinks

2025-07-06T09:04:12Z

commit ff8abbd248c1f52df0c321690b88454b13ff54b2 upstream. Some users and customers reported that their backup/copy tools started to fail when the directory being copied contained symlink targets that the client couldn't parse - even when those symlinks weren't followed. Fix this by allowing lstat(2) and readlink(2) to succeed even when the client can't resolve the symlink target, restoring old behavior. Cc: linux-cifs@vger.kernel.org Cc: stable@vger.kernel.org Reported-by: Remy Monsen Closes: https://lore.kernel.org/r/CAN+tdP7y=jqw3pBndZAGjQv0ObFq8Q=+PUDHgB36HdEz9QA6FQ@mail.gmail.com Reported-by: Pierguido Lambri Fixes: 12b466eb52d9 ("cifs: Fix creating and resolving absolute NT-style symlinks") Signed-off-by: Paulo Alcantara (Red Hat) Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman

cifs: Remove duplicate fattr->cf_dtype assignment from wsl_to_fattr() function

2025-06-27T10:13:43Z

[ Upstream commit 840738eae94864993a735ab677b9795bb8f3b961 ] Commit 8bd25b61c5a5 ("smb: client: set correct d_type for reparse DFS/DFSR and mount point") deduplicated assignment of fattr->cf_dtype member from all places to end of the function cifs_reparse_point_to_fattr(). The only one missing place which was not deduplicated is wsl_to_fattr(). Fix it. Fixes: 8bd25b61c5a5 ("smb: client: set correct d_type for reparse DFS/DFSR and mount point") Signed-off-by: Pali Rohár Signed-off-by: Steve French Signed-off-by: Sasha Levin

cifs: Split parse_reparse_point callback to functions: get buffer and parse buffer

2025-04-09T20:37:35Z

Parsing reparse point buffer is generic for all SMB versions and is already implemented by global function parse_reparse_point(). Getting reparse point buffer from the SMB response is SMB version specific, so introduce for it a new callback get_reparse_point_buffer. This functionality split is needed for followup change - getting reparse point buffer without parsing it. Signed-off-by: Pali Rohár Signed-off-by: Steve French

cifs: Improve handling of name surrogate reparse points in reparse.c

2025-04-09T20:37:26Z

Like previous changes for file inode.c, handle directory name surrogate reparse points generally also in reparse.c. Signed-off-by: Pali Rohár Signed-off-by: Steve French

cifs: Fix support for WSL-style symlinks

2025-04-08T23:38:03Z

MS-FSCC in section 2.1.2.7 LX SYMLINK REPARSE_DATA_BUFFER now contains documentation about WSL symlink reparse point buffers. https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/68337353-9153-4ee1-ac6b-419839c3b7ad Fix the struct reparse_wsl_symlink_data_buffer to reflect buffer fields according to the MS-FSCC documentation. Fix the Linux SMB client to correctly fill the WSL symlink reparse point buffer when creaing new WSL-style symlink. There was a mistake during filling the data part of the reparse point buffer. It should starts with bytes "\x02\x00\x00\x00" (which represents version 2) but this constant was written as number 0x02000000 encoded in little endian, which resulted bytes "\x00\x00\x00\x02". This change is fixing this mistake. Fixes: 4e2043be5c14 ("cifs: Add support for creating WSL-style symlinks") Signed-off-by: Pali Rohár Signed-off-by: Steve French

cifs: Ensure that all non-client-specific reparse points are processed by the server

2025-04-07T06:07:22Z

Fix regression in mounts to e.g. onedrive shares. Generally, reparse points are processed by the SMB server during the SMB OPEN request, but there are few reparse points which do not have OPEN-like meaning for the SMB server and has to be processed by the SMB client. Those are symlinks and special files (fifo, socket, block, char). For Linux SMB client, it is required to process also name surrogate reparse points as they represent another entity on the SMB server system. Linux client will mark them as separate mount points. Examples of name surrogate reparse points are NTFS junction points (e.g. created by the "mklink" tool on Windows servers). So after processing the name surrogate reparse points, clear the -EOPNOTSUPP error code returned from the parse_reparse_point() to let SMB server to process reparse points. And remove printing misleading error message "unhandled reparse tag:" as reparse points are handled by SMB server and hence unhandled fact is normal operation. Fixes: cad3fc0a4c8c ("cifs: Throw -EOPNOTSUPP error on unsupported reparse point type from parse_reparse_point()") Fixes: b587fd128660 ("cifs: Treat unhandled directory name surrogate reparse points as mount directory nodes") Cc: stable@vger.kernel.org Reported-by: Junwen Sun Tested-by: Junwen Sun Signed-off-by: Pali Rohár Signed-off-by: Steve French

cifs: Throw -EOPNOTSUPP error on unsupported reparse point type from parse_reparse_point()

2025-02-19T16:42:25Z

This would help to track and detect by caller if the reparse point type was processed or not. Signed-off-by: Pali Rohár Signed-off-by: Steve French

cifs: Add support for creating WSL-style symlinks

2025-01-31T18:51:44Z

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 Signed-off-by: Steve French