[yocto] [meta-selinux][PATCHv2 0/8] Label file system in build.
Joe MacDonald
Joe_MacDonald at mentor.com
Sat Aug 8 14:00:56 PDT 2015
Hi Phil,
I'm sorry this has been in the merge queue for so long. I've merged it
after taking the policy updates from Shrikant and a few other small
patches that had been hanging around too. I didn't drop it on master
yet, though, since I wanted to give everyone else a little bit of time
to try it out (myself included, I'm finally able to come up for air on
some of the day job things :-)). Instead it is currently living on the
fs_label branch, but I rebased the patches on the current master HEAD
commit. That means, though, that if you get a chance I'd like to take a
look at the branch to ensure I didn't mangle your patch set too much.
-J.
[[meta-selinux][PATCHv2 0/8] Label file system in build.] On 15.06.17 (Wed 15:30) Philip Tricca wrote:
> This is the second version of a patch series that allows the file system
> of SELinux images to be labeled as part of the build process. This will
> allow SELinux images to boot read only file systems and remove the need to
> label the file system on first boot.
>
> To do this we must label the file system in the build as well as add
> support for extended attributes to the mke2fs utility in the e2fsprogs
> package. The first version of this patch series is here:
> https://lists.yoctoproject.org/pipermail/yocto/2015-June/025141.html
> The approach described in this previous RFC remains the same.
>
> Changes in v2:
> This second version has two significant changes: First I've done a bunch
> of cleanup. This includes work to make the descriptions in the patch
> headers / commit messages more exact as well as combining some commits
> with related functionality. Secondly I've reimplemented the xattr cache
> so that it actually works.
>
> I've made the patch headers as descriptive as possible and kept the git
> commit messages minimal. If the preference is for more verbose commit
> messages I'm happy to oblige if advised.
>
> The cache is just a single linked list that's searched for duplicates after
> the creation of each new xattr block. The previous implementation was similar
> but, aside from not working properly, it was overly complex in its attempt to
> keep the list sorted.
>
> Tests:
> To test this new implementation I used the core-image-selinux-minimal image
> from the unmodified master branch as a control. This image has 2536 unique
> file system objects including the root fs directory. The ext4 file system
> produced by the build has 71492 blocks with 13621 free.
>
> As an additional test I added the patches from this set WITHOUT the cache
> patches. This causes each file system object with an associated extended
> attribute to use up an additional block for the xattr. This should cause
> (hypothesis) the output file system to have 13621 - 2536 = 11085 free
> blocks. The build producing an ext4 file system with 71492 blocks and 11088
> free. That's an additional 2533 blocks used instead of the 2536 expected.
> These 3 missing xattr blocks can be accounted for in that there are 3
> unlabeled files in the file system.
>
> Introducing the cache allows files with identical xattr blocks to share
> them to reduce the number of used blocks. Since we're only storing SELinux
> labels in the xattrs we can say that every file with the same SELinux label
> should share an xattr block. Counting the unique SELinux labels on file
> objects we know that there are 83 in total. The second hypothesis we have
> to test then is that using the cache will reduce the number of used blocks
> from 2533 down to 83.
>
> Applying the patch that enables the cache produces a third and final ext4
> file system. This one again report 71492 total blocks but this time 13538
> free. This is 83 blocks fewer than the unlabled file system from the
> initial test as we expected. The code added by this patch set is also
> instrumented to count the objects in the cache when they're freed. With
> this debug output enabled it reports the same number of objects in the
> cache.
>
> From the test results I'm pretty confident that the cache functions as
> expected. It's still a very basic implementation but given the small
> number of unique SELinux labels in the reference file systems it's
> likely sufficient for a first version. Feedback / comments on both the
> implementation and testing approach would be appreciated.
>
> Regards,
> Philip
> ----
>
> Philip Tricca (8):
> policycoreutils: Patch setfiles to add FTS_NOCHDIR to fts_flags.
> selinux-image: Add new image class to label the rootfs, use it for
> selinux images.
> e2fsprogs: Add bbappend and stub for xattr module.
> e2fsprogs: Insert calls to xattr module into mke2fs and build xattr
> code.
> e2fsprogs: Add xattr security prefix data to
> lib/ext2fs/ext2_ext_attr.h
> e2fsprogs: Copy xattr block from source file.
> e2fsprogs: Add stub functions for an xattr cache and struct to hold
> the header and block data.
> e2fsprogs: Implement xattr block cache with simple linked list.
>
> classes/selinux-image.bbclass | 8 +
> ...ib-ext2fs-ext2_ext_attr.h-add-xattr-index.patch | 20 ++
> .../misc-xattr-add-xattr-module-stub.patch | 57 ++++
> .../misc-xattr-create-xattr-block-node.patch | 175 +++++++++++
> .../e2fsprogs/misc-xattr-create-xattr-block.patch | 341 +++++++++++++++++++++
> .../e2fsprogs/misc-xattr-create-xattr-cache.patch | 181 +++++++++++
> .../mke2fs.c-create_inode.c-copy-xattrs.patch | 164 ++++++++++
> .../e2fsprogs/e2fsprogs_1.42.9.bbappend | 10 +
> .../images/core-image-selinux-minimal.bb | 2 +-
> recipes-security/images/core-image-selinux.bb | 2 +-
> .../policycoreutils-fts_flags-FTS_NOCHDIR.patch | 25 ++
> recipes-security/selinux/policycoreutils_2.3.bb | 1 +
> 12 files changed, 984 insertions(+), 2 deletions(-)
> create mode 100644 classes/selinux-image.bbclass
> create mode 100644 recipes-devtools/e2fsprogs/e2fsprogs/lib-ext2fs-ext2_ext_attr.h-add-xattr-index.patch
> create mode 100644 recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-add-xattr-module-stub.patch
> create mode 100644 recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-block-node.patch
> create mode 100644 recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-block.patch
> create mode 100644 recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-cache.patch
> create mode 100644 recipes-devtools/e2fsprogs/e2fsprogs/mke2fs.c-create_inode.c-copy-xattrs.patch
> create mode 100644 recipes-devtools/e2fsprogs/e2fsprogs_1.42.9.bbappend
> create mode 100644 recipes-security/selinux/policycoreutils/policycoreutils-fts_flags-FTS_NOCHDIR.patch
>
--
-Joe MacDonald.
:wq
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