[PATCH 6.18.y 2/2] smb: client: fix WSL reparse point uid/gid override

[Sasha Levin <sashal@kernel.org>]

From: Paulo Alcantara <pc@manguebit.org>

[ Upstream commit cd2b2b57921d4caa7875e83198bb2aa71254328b ]

wsl_to_fattr() unconditionally overwrites cf_uid/cf_gid with values
from WSL extended attributes ($LXUID/$LXGID), ignoring the forceuid
and forcegid mount options.

Fix this by initializing cf_uid/cf_gid to the mount defaults and
gating the $LXUID/$LXGID EA parsing on forceuid/forcegid.

Closes: https://sashiko.dev/#/patchset/20260906190803.667489-1-pc%40manguebit.org
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Shyam Prasad N <sprasad@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Bharath SM <bharathsm@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/smb/client/reparse.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c
index 58bd67f32377f..383eb9bd45793 100644
--- a/fs/smb/client/reparse.c
+++ b/fs/smb/client/reparse.c
@@ -1108,10 +1108,14 @@ static bool wsl_to_fattr(struct cifs_open_info_data *data,
 			 struct cifs_sb_info *cifs_sb,
 			 u32 tag, struct cifs_fattr *fattr)
 {
+	unsigned int sbflags = cifs_sb_flags(cifs_sb);
 	struct smb2_file_full_ea_info *ea;
 	bool have_xattr_dev = false;
 	u32 next = 0;
 
+	fattr->cf_uid = cifs_sb->ctx->linux_uid;
+	fattr->cf_gid = cifs_sb->ctx->linux_gid;
+
 	switch (tag) {
 	case IO_REPARSE_TAG_LX_SYMLINK:
 		fattr->cf_mode |= S_IFLNK;
@@ -1148,11 +1152,13 @@ static bool wsl_to_fattr(struct cifs_open_info_data *data,
 		nlen = ea->ea_name_length;
 		v = (void *)((u8 *)ea->ea_data + ea->ea_name_length + 1);
 
-		if (!strncmp(name, SMB2_WSL_XATTR_UID, nlen))
-			fattr->cf_uid = wsl_make_kuid(cifs_sb, v);
-		else if (!strncmp(name, SMB2_WSL_XATTR_GID, nlen))
-			fattr->cf_gid = wsl_make_kgid(cifs_sb, v);
-		else if (!strncmp(name, SMB2_WSL_XATTR_MODE, nlen)) {
+		if (!strncmp(name, SMB2_WSL_XATTR_UID, nlen)) {
+			if (!(sbflags & CIFS_MOUNT_OVERR_UID))
+				fattr->cf_uid = wsl_make_kuid(cifs_sb, v);
+		} else if (!strncmp(name, SMB2_WSL_XATTR_GID, nlen)) {
+			if (!(sbflags & CIFS_MOUNT_OVERR_GID))
+				fattr->cf_gid = wsl_make_kgid(cifs_sb, v);
+		} else if (!strncmp(name, SMB2_WSL_XATTR_MODE, nlen)) {
 			/* File type in reparse point tag and in xattr mode must match. */
 			if (S_DT(fattr->cf_mode) != S_DT(le32_to_cpu(*(__le32 *)v)))
 				return false;
-- 
2.53.0