Dear Yamada-san, On Do, Mai 23, 2019 at 02:18:00 +0200, Roberto Sassu wrote: > This patch set aims at solving the following use case: appraise files from > the initial ram disk. To do that, IMA checks the signature/hash from the > security.ima xattr. Unfortunately, this use case cannot be implemented > currently, as the CPIO format does not support xattrs. > > This proposal consists in including file metadata as additional files named > METADATA!!!, for each file added to the ram disk. The CPIO parser in the > kernel recognizes these special files from the file name, and calls the > appropriate parser to add metadata to the previously extracted file. It has > been proposed to use bit 17:16 of the file mode as a way to recognize files > with metadata, but both the kernel and the cpio tool declare the file mode > as unsigned short. > > The difference from v2, v3 (https://lkml.org/lkml/2019/5/9/230, > https://lkml.org/lkml/2019/5/17/466) is that file metadata are stored in > separate files instead of a single file. Given that files with metadata > must immediately follow the files metadata will be added to, image > generators have to be modified in this version. > > The difference from v1 (https://lkml.org/lkml/2018/11/22/1182) is that > all files have the same name. The file metadata are added to is always the > previous one, and the image generator in user space will make sure that > files are in the correct sequence. > > The difference with another proposal > (https://lore.kernel.org/patchwork/cover/888071/) is that xattrs can be > included in an image without changing the image format. Files with metadata > will appear as regular files. It will be task of the parser in the kernel > to process them. > > This patch set extends the format of data defined in patch 9/15 of the last > proposal. It adds header version and type, so that new formats can be > defined and arbitrary metadata types can be processed. > > The changes introduced by this patch set don't cause any compatibility > issue: kernels without the metadata parser simply extract the special files > and don't process metadata; kernels with the metadata parser don't process > metadata if the special files are not included in the image. > > >From the kernel space perspective, backporting this functionality to older > kernels should be very easy. It is sufficient to add two calls to the new > function do_process_metadata() in do_copy(), and to check the file name in > do_name(). From the user space perspective, unlike the previous version of > the patch set, it is required to modify the image generators in order to > include metadata as separate files. Since this patch series most likely falls under your jurisdiction and also given your recent commits [*] in the same area, I am curious if there are any early signs which would prevent your final acceptance and would potentially result in a no-Go? Can we have an early confirmation that, upon rebasing and handling of all the review comments, you would be willing to accept the patches? [*] Most recent commits touching usr/gen_initramfs.sh https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7168965ec7b10b8a2c7dea1f82f1ebadf44d64ba https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=65e00e04e5aea34b256814cfa21b32e3b94a2402 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=469e87e89fd61de804bd29f6dd0380a399b567a7 Thanks, Eugeniu.
