linux-kernel - Re: [RFC] setxattr bugs

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: <510E6D3F.2060200@oracle.com>
Date:	Sun, 03 Feb 2013 07:59:27 -0600
From:	Dave Kleikamp <dave.kleikamp@...cle.com>
To:	Al Viro <viro@...IV.linux.org.uk>
CC:	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-fsdevel@...r.kernel.org, Jeff Mahoney <jeffm@...e.com>,
	Dave Kleikamp <shaggy@...nel.org>
Subject: Re: [RFC] setxattr bugs

On 02/02/2013 10:30 PM, Al Viro wrote:
> 	* JFS, since 2005: setxattr(name, "system.posix_acl_access", NULL, 0, 0)
> succeeds, creating an empty EA with "system.posix_acl_access" as name.
> Validity checks should apply _after_
>         if (value == NULL) {    /* empty EA, do not remove */
>                 value = "";
>                 value_len = 0;
>         }
> and not before it.

This is probably a hold-over from weird OS/2 behavior that we really
don't need to keep.

> 	* reiserfs, since 2009: setxattr(name, attr_name, NULL, 0, 0) is
> treated as removexattr(name, attr_name), not as emptying given xattr.
> 
> 	The question is, does either of those cross into "established
> weirdness in ABI" or are they still at the "bugs to be fixed" stage?
> 
> 	FWIW, I'm seriously tempted to stop passing NULL as the
> third argument of ->setxattr(), essentially taking all those
> if (!value) value = ""; pieces from individual ->setxattr() instances
> to __vfs_setxattr_noperm() (all other callers of ->setxattr() never
> pass NULL data or 0 size, so it's irrelevant for them).  Would fix
> both jfs and reiserfs weirdness....
> 
> 	Objections?

no objection from me. I can clean up the jfs code so that it no longer
saves empty xattrs.

Thanks,
Shaggy
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/