On Fri, 2023-04-07 at 10:31 +0200, Christian Brauner wrote: > So, I think we want both; we want the ovl_copyattr() and the > vfs_getattr_nosec() change: > > (1) overlayfs should copy up the inode version in ovl_copyattr(). That > is in line what we do with all other inode attributes. IOW, the > overlayfs inode's i_version counter should aim to mirror the > relevant layer's i_version counter. I wouldn't know why that > shouldn't be the case. Asking the other way around there doesn't > seem to be any use for overlayfs inodes to have an i_version that > isn't just mirroring the relevant layer's i_version. > (2) Jeff's changes for ima to make it rely on vfs_getattr_nosec(). > Currently, ima assumes that it will get the correct i_version from > an inode but that just doesn't hold for stacking filesystem. > > While (1) would likely just fix the immediate bug (2) is correct and > _robust_. If we change how attributes are handled vfs_*() helpers will > get updated and ima with it. Poking at raw inodes without using > appropriate helpers is much more likely to get ima into trouble. In addition to properly setting the i_version for IMA, EVM has a similar issue with i_generation and s_uuid. Adding them to ovl_copyattr() seems to resolve it. Does that make sense? diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index 923d66d131c1..cd0aeb828868 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -1118,5 +1118,8 @@ void ovl_copyattr(struct inode *inode) inode->i_atime = realinode->i_atime; inode->i_mtime = realinode->i_mtime; inode->i_ctime = realinode->i_ctime; + inode->i_generation = realinode->i_generation; + if (inode->i_sb) + uuid_copy(&inode->i_sb->s_uuid, &realinode->i_sb- >s_uuid); i_size_write(inode, i_size_read(realinode)); } -- thanks, Mimib
