From a082c6f680da298cf075886ff032f32ccb7c5e1a Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Mon, 29 May 2017 15:15:27 +0200 Subject: [PATCH] ovl: filter trusted xattr for non-admin 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 --- fs/overlayfs/inode.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index ad9547f..d613e2c 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -240,6 +240,16 @@ int ovl_xattr_get(struct dentry *dentry, const char *name, 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); @@ -263,7 +273,7 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) return -EIO; len -= slen; - if (ovl_is_private_xattr(s)) { + if (!ovl_can_list(s)) { res -= slen; memmove(s, s + slen, len); } else { -- 2.7.4