From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Wed, 1 Jul 2026 13:35:11 +0000 (+0200)
Subject: 6.18-stable patches
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=05a05194f3e4e04a737a3c04c663b095e5e528df;p=thirdparty%2Fkernel%2Fstable-queue.git

6.18-stable patches

added patches:
	ntfs3-reject-direct-userspace-writes-to-reserved-lx-xattrs.patch
---

diff --git a/queue-6.18/ntfs3-reject-direct-userspace-writes-to-reserved-lx-xattrs.patch b/queue-6.18/ntfs3-reject-direct-userspace-writes-to-reserved-lx-xattrs.patch
new file mode 100644
index 0000000000..a0e06b49e2
--- /dev/null
+++ b/queue-6.18/ntfs3-reject-direct-userspace-writes-to-reserved-lx-xattrs.patch
@@ -0,0 +1,58 @@
+From 5b08dccecf825cbf905f348bc6ccb497507e28e2 Mon Sep 17 00:00:00 2001
+From: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
+Date: Wed, 10 Jun 2026 12:31:01 +0200
+Subject: ntfs3: reject direct userspace writes to reserved $LX* xattrs
+
+From: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
+
+commit 5b08dccecf825cbf905f348bc6ccb497507e28e2 upstream.
+
+NTFS3 uses $LXUID, $LXGID, $LXMOD and $LXDEV as internal WSL
+permission metadata and reloads them into i_uid, i_gid and i_mode
+from ntfs_get_wsl_perm().
+
+Because the empty-prefix xattr handler also lets file owners call
+setxattr() on these names directly, an unprivileged writer on a
+writable ntfs3 mount can plant root ownership and S_ISUID on their own
+file and gain euid 0 after inode reload.
+
+Reject direct userspace writes to the reserved $LX* names. Internal
+ntfs3 metadata updates are unchanged because ntfs_save_wsl_perm()
+writes them via ntfs_set_ea() directly.
+
+Signed-off-by: Zhen Yan <sdjasjbuaa@gmail.com>
+[almaz.alexandrovich@paragon-software.com: added an additional check for non privileged users]
+Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/ntfs3/xattr.c |   12 ++++++++++++
+ 1 file changed, 12 insertions(+)
+
+--- a/fs/ntfs3/xattr.c
++++ b/fs/ntfs3/xattr.c
+@@ -845,6 +845,12 @@ out:
+ 	return err;
+ }
+ 
++static bool ntfs_is_reserved_lxattr(const char *name)
++{
++	return !strcmp(name, "$LXUID") || !strcmp(name, "$LXGID") ||
++	       !strcmp(name, "$LXMOD") || !strcmp(name, "$LXDEV");
++}
++
+ /*
+  * ntfs_setxattr - inode_operations::setxattr
+  */
+@@ -949,6 +955,12 @@ set_new_fa:
+ 		goto out;
+ 	}
+ 
++	/* Do not allow non privileged users to change $LXUID/$LXGID... */
++	if (ntfs_is_reserved_lxattr(name) && !capable(CAP_SYS_ADMIN)) {
++		err = -EPERM;
++		goto out;
++	}
++
+ 	/* Deal with NTFS extended attribute. */
+ 	err = ntfs_set_ea(inode, name, strlen(name), value, size, flags, 0,
+ 			  NULL);
diff --git a/queue-6.18/series b/queue-6.18/series
index 5e6eeaf60c..d8c82c42d7 100644
--- a/queue-6.18/series
+++ b/queue-6.18/series
@@ -31,3 +31,4 @@ batman-adv-tvlv-enforce-2-byte-alignment.patch
 batman-adv-tvlv-avoid-race-of-cifsnotfound-handler-s.patch
 ipv6-account-for-fraggap-on-the-paged-allocation-path.patch
 ipv4-account-for-fraggap-on-the-paged-allocation-pat.patch
+ntfs3-reject-direct-userspace-writes-to-reserved-lx-xattrs.patch