Messages in this thread | | | Subject | Re: [PATCH v4 0/3] initramfs: add support for xattrs in the initial ram disk | From | Roberto Sassu <> | Date | Wed, 24 Jul 2019 17:34:53 +0200 |
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Is there anything I didn't address in this patch set, that is delaying the review? I would appreciate if you can give me a feedback, positive or negative.
Thanks a lot!
Roberto
On 7/15/2019 6:54 PM, Roberto Sassu wrote: > Rob, Peter, Arvind, did you have the chance to have a look at this > version of the patch set? > > Thanks > > Roberto > > > On 7/1/2019 4:31 PM, Mimi Zohar wrote: >> On Mon, 2019-07-01 at 16:42 +0300, Roberto Sassu wrote: >>> On 6/30/2019 6:39 PM, Mimi Zohar wrote: >>>> On Wed, 2019-06-26 at 10:15 +0200, Roberto Sassu wrote: >>>>> On 6/3/2019 8:32 PM, Rob Landley wrote: >>>>>> On 6/3/19 4:31 AM, 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. >>>>>>> >>>>>>> Any opinion on this patch set? >>>>>>> >>>>>>> Thanks >>>>>>> >>>>>>> Roberto >>>>>> >>>>>> Sorry, I've had the window open since you posted it but haven't >>>>>> gotten around to >>>>>> it. I'll try to build it later today. >>>>>> >>>>>> It does look interesting, and I have no objections to the basic >>>>>> approach. I >>>>>> should be able to add support to toybox cpio over a weekend once >>>>>> I've got the >>>>>> kernel doing it to test against. >>>>> >>>>> Ok. >>>>> >>>>> Let me give some instructions so that people can test this patch set. >>>>> >>>>> To add xattrs to the ram disk embedded in the kernel it is sufficient >>>>> to set CONFIG_INITRAMFS_FILE_METADATA="xattr" and >>>>> CONFIG_INITRAMFS_SOURCE="<file with xattr>" in the kernel >>>>> configuration. >>>>> >>>>> To add xattrs to the external ram disk, it is necessary to patch cpio: >>>>> >>>>> https://github.com/euleros/cpio/commit/531cabc88e9ecdc3231fad6e4856869baa9a91ef >>>>> >>>>> (xattr-v1 branch) >>>>> >>>>> and dracut: >>>>> >>>>> https://github.com/euleros/dracut/commit/a2dee56ea80495c2c1871bc73186f7b00dc8bf3b >>>>> >>>>> (digest-lists branch) >>>>> >>>>> The same modification can be done for mkinitramfs (add '-e xattr' >>>>> to the >>>>> cpio command line). >>>>> >>>>> To simplify the test, it would be sufficient to replace only the cpio >>>>> binary and the dracut script with the modified versions. For >>>>> dracut, the >>>>> patch should be applied to the local dracut (after it has been renamed >>>>> to dracut.sh). >>>>> >>>>> Then, run: >>>>> >>>>> dracut -e xattr -I <file with xattr> (add -f to overwrite the ram >>>>> disk) >>>>> >>>>> Xattrs can be seen by stopping the boot process for example by adding >>>>> rd.break to the kernel command line. >>>> >>>> A simple way of testing, without needing any changes other than the >>>> kernel patches, is to save the dracut temporary directory by supplying >>>> "--keep" on the dracut command line, calling >>>> usr/gen_initramfs_list.sh, followed by usr/gen_init_cpio with the "-e >>>> xattr" option. >>> >>> Alternatively, follow the instructions to create the embedded ram disk >>> with xattrs, and use the existing external ram disk created with dracut >>> to check if xattrs are created. >> >> True, but this alternative is for those who normally use dracut to >> create an initramfs, but don't want to update cpio or dracut. >> >> Mimi >> >
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