linux-ext4 - Re: [PATCH 06/11] fsverity: push out fsverity

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20260126043311.GC30803@lst.de>
Date: Mon, 26 Jan 2026 05:33:11 +0100
From: Christoph Hellwig <hch@....de>
To: Eric Biggers <ebiggers@...nel.org>
Cc: Christoph Hellwig <hch@....de>, Al Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
	David Sterba <dsterba@...e.com>, Theodore Ts'o <tytso@....edu>,
	Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <chao@...nel.org>,
	Andrey Albershteyn <aalbersh@...hat.com>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	linux-fsdevel@...r.kernel.org, linux-btrfs@...r.kernel.org,
	linux-ext4@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net,
	fsverity@...ts.linux.dev
Subject: Re: [PATCH 06/11] fsverity: push out fsverity_info lookup

On Sat, Jan 24, 2026 at 01:19:56PM -0800, Eric Biggers wrote:
> This patch introduces another bisection hazard by adding calls to
> fsverity_info_addr() when CONFIG_FS_VERITY=n.  fsverity_info_addr() has
> a definition only when CONFIG_FS_VERITY=y.
> 
> Maybe temporarily add a CONFIG_FS_VERITY=n stub for fsverity_info_addr()
> that returns NULL, and also ensure that it's dereferenced only when it's
> known that fsverity verification is needed.  Most of the call sites look
> okay, but the second one in ext4_mpage_readpages() needs to be fixed.

I've added an external declaration for fsverity_info_addr in the
CONFIG_FS_VERITY=n so that the linker catches unguarded references.  It 
caught two, which I fixed by adding IS_ENABLED checks that also reduce
the code size for non-fsverity builds.

> > -	fsverity_init_verification_context(&ctx, inode);
> > +	fsverity_init_verification_context(&ctx, inode, vi);
> 
> Note that fsverity_info has a back-pointer to the inode.  So,
> fsverity_init_verification_context() could just take the vi and set
> ctx->inode to vi->inode.
> 
> Then it wouldn't be necessary to get the inode from
> bio_first_folio_all(bio)->mapping->host (in fsverity_verify_bio()) or
> folio->mapping->host (in fsverity_verify_blocks()).
> Similarly in fsverity_readahead() too.
> 
> (It might make sense to handle this part as a separate patch.)

To be able to nicely used this vi->inode needs to lose the const
qualifier.  I've done that, and also added a const qualifiers
to ctx->vi while at it in prep patches.  With that just using
vi->inode in this patch is easy enough.