From b581755b1c565391c72d03b157ba2dd0b18e9d15 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Mon, 6 Jun 2016 16:21:37 +0200 Subject: [PATCH] ovl: xattr filter fix a) ovl_need_xattr_filter() is wrong, we can have multiple lower layers overlaid, all of which (except the lowest one) honouring the "trusted.overlay.opaque" xattr. So need to filter everything except the bottom and the pure-upper layer. b) we no longer can assume that inode is attached to dentry in get/setxattr. This patch unconditionally filters private xattrs to fix both of the above. Performance impact for get/removexattrs is likely in the noise. For listxattrs it might be measurable in pathological cases, but I very much hope nobody cares. If they do, we'll fix it then. Reported-by: Vivek Goyal Signed-off-by: Miklos Szeredi Fixes: b96809173e94 ("security_d_instantiate(): move to the point prior to attaching dentry to inode") --- fs/overlayfs/inode.c | 26 ++++++-------------------- 1 file changed, 6 insertions(+), 20 deletions(-) diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 0ed7c4012437..1dbeab6cf96e 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -238,41 +238,27 @@ int ovl_setxattr(struct dentry *dentry, struct inode *inode, return err; } -static bool ovl_need_xattr_filter(struct dentry *dentry, - enum ovl_path_type type) -{ - if ((type & (__OVL_PATH_PURE | __OVL_PATH_UPPER)) == __OVL_PATH_UPPER) - return S_ISDIR(dentry->d_inode->i_mode); - else - return false; -} - ssize_t ovl_getxattr(struct dentry *dentry, struct inode *inode, const char *name, void *value, size_t size) { - struct path realpath; - enum ovl_path_type type = ovl_path_real(dentry, &realpath); + struct dentry *realdentry = ovl_dentry_real(dentry); - if (ovl_need_xattr_filter(dentry, type) && ovl_is_private_xattr(name)) + if (ovl_is_private_xattr(name)) return -ENODATA; - return vfs_getxattr(realpath.dentry, name, value, size); + return vfs_getxattr(realdentry, name, value, size); } ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) { - struct path realpath; - enum ovl_path_type type = ovl_path_real(dentry, &realpath); + struct dentry *realdentry = ovl_dentry_real(dentry); ssize_t res; int off; - res = vfs_listxattr(realpath.dentry, list, size); + res = vfs_listxattr(realdentry, list, size); if (res <= 0 || size == 0) return res; - if (!ovl_need_xattr_filter(dentry, type)) - return res; - /* filter out private xattrs */ for (off = 0; off < res;) { char *s = list + off; @@ -302,7 +288,7 @@ int ovl_removexattr(struct dentry *dentry, const char *name) goto out; err = -ENODATA; - if (ovl_need_xattr_filter(dentry, type) && ovl_is_private_xattr(name)) + if (ovl_is_private_xattr(name)) goto out_drop_write; if (!OVL_TYPE_UPPER(type)) {