From: David Disseldorp <ddiss@suse.de>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org,
Martin Wilck <mwilck@suse.com>,
viro@zeniv.linux.org.uk, Jeff Mahoney <jeffm@suse.com>
Subject: Re: [PATCH v4 2/4] initramfs: print helpful cpio error on "crc" magic
Date: Wed, 10 Nov 2021 21:54:20 +0100 [thread overview]
Message-ID: <20211110215420.1ef91d86@suse.de> (raw)
In-Reply-To: <YYwBzj0isuKOjjUe@casper.infradead.org>
On Wed, 10 Nov 2021 17:30:54 +0000, Matthew Wilcox wrote:
> On Wed, Nov 10, 2021 at 01:38:48PM +0100, David Disseldorp wrote:
> > Contrary to the buffer-format.rst documentation, initramfs cpio
> > extraction does not support "crc" archives, which carry "070702"
> > header magic. Make it a little clearer that "newc" (magic="070701") is
> > the only supported cpio format, by extending the POSIX.1 ASCII
> > (magic="070707") specific error message to also cover "crc" magic.
>
> Wouldn't it be easier to just add support?
Well, no, this patch already exists. :-)
> As far as I can tell from
> looking at documentation, the "crc" format is the same as newc, except
> that it uses some reserved bits to store the crc. Since we ignore those
> bits, we could just check for either 070701 or 070702.
Sure, it'd be pretty straightforward to implement "crc" format support,
but I'm not sure how useful a 32-bit checksum would be... If we're going
down this route, wouldn't proper IMA/EVM support make sense via some new
cpio variant with space for the attributes (or as header/trailer like
bootconfig)?
cc'ing Jeff, as I seem to recall him mentioning some work in this area.
Cheers, David
next prev parent reply other threads:[~2021-11-10 20:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-10 12:38 [PATCH v4 0/4] initramfs: "crc" cpio format and INITRAMFS_PRESERVE_MTIME David Disseldorp
2021-11-10 12:38 ` [PATCH v4 1/4] initramfs: refactor do_header() cpio magic checks David Disseldorp
2021-11-10 12:38 ` [PATCH v4 2/4] initramfs: print helpful cpio error on "crc" magic David Disseldorp
2021-11-10 17:30 ` Matthew Wilcox
2021-11-10 20:54 ` David Disseldorp [this message]
2021-11-10 12:38 ` [PATCH v4 3/4] docs: remove mention of "crc" cpio format support David Disseldorp
2021-11-10 12:38 ` [PATCH v4 4/4] initramfs: add INITRAMFS_PRESERVE_MTIME Kconfig option David Disseldorp
2021-11-10 12:42 ` [PATCH v4 0/4] initramfs: "crc" cpio format and INITRAMFS_PRESERVE_MTIME Martin Wilck
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211110215420.1ef91d86@suse.de \
--to=ddiss@suse.de \
--cc=jeffm@suse.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=mwilck@suse.com \
--cc=viro@zeniv.linux.org.uk \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).