4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Miklos Szeredi <mszeredi@xxxxxxxxxx>
[ Upstream commit a082c6f680da298cf075886ff032f32ccb7c5e1a ]
Filesystems filter out extended attributes in the "trusted." domain for
unprivlieged callers.
Overlay calls underlying filesystem's method with elevated privs, so need
to do the filtering in overlayfs too.
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/overlayfs/inode.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -227,6 +227,16 @@ int ovl_xattr_get(struct dentry *dentry,
return res;
}
+static bool ovl_can_list(const char *s)
+{
+ /* List all non-trusted xatts */
+ if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0)
+ return true;
+
+ /* Never list trusted.overlay, list other trusted for superuser only */
+ return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN);
+}
+
ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
{
struct dentry *realdentry = ovl_dentry_real(dentry);
@@ -250,7 +260,7 @@ ssize_t ovl_listxattr(struct dentry *den
return -EIO;
len -= slen;
- if (ovl_is_private_xattr(s)) {
+ if (!ovl_can_list(s)) {
res -= slen;
memmove(s, s + slen, len);
} else {