4.9-stable review patch. If anyone has any objections, please let me know.
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From: Miklos Szeredi mszeredi@redhat.com
[ 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@redhat.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 {