From: Al Viro <viro@ZenIV.linux.org.uk>
To: NeilBrown <neilb@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Christoph Hellwig <hch@lst.de>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Eric Biederman <ebiederm@xmission.com>
Subject: Re: dcache: remove trylock loops (was Re: [BUG] lock_parent() breakage when used from shrink_dentry_list())
Date: Sat, 28 Apr 2018 01:10:03 +0100 [thread overview]
Message-ID: <20180428001003.GA14907@ZenIV.linux.org.uk> (raw)
In-Reply-To: <87o9jsdbho.fsf@notabene.neil.brown.name>
On Tue, Mar 13, 2018 at 12:12:51PM +1100, NeilBrown wrote:
> > * selinux inode_doinit_with_dentry() (two call sites, very alike)
>
> I'm less sure about this one, but I think it probably wants
> d_find_any_alias() as well. Like cap_inode_getsecurity() it only wants
> a dentry so that it can pass something to __vfs_getxattr(),
> and that only wants a dentry so it can pass something to ->get.
>
> Possibly we should rename d_find_alias() to d_find_hashed_alias() so that
> people need to make a conscious choice between d_find_hashed_alias() and
> d_find_any_alias() ??
FWIW, it *is* a bug; this
/*
* this is can be hit on boot when a file is accessed
* before the policy is loaded. When we load policy we
* may find inodes that have no dentry on the
* sbsec->isec_head list. No reason to complain as these
* will get fixed up the next time we go through
* inode_doinit with a dentry, before these inodes could
* be used again by userspace.
*/
in selinux/hooks.c is flat-out wrong now. Sure, if you first load selinux
policy after exporting something over NFS or letting attacker play with
open-by-fhandle, you are past any help, but still...
I disagree about going for d_find_any_alias() from the very beginning, BTW -
we need to try it in case of d_find_alias() failure, but sufficiently crappy
filesystem can bloody well fail to access xattrs via disconnected dentry.
next prev parent reply other threads:[~2018-04-28 0:10 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-22 23:50 [PATCH v2 0/6] fs/dcache: avoid trylock loops John Ogness
2018-02-22 23:50 ` [PATCH v2 1/6] fs/dcache: Remove stale comment from dentry_kill() John Ogness
2018-02-22 23:50 ` [PATCH v2 2/6] fs/dcache: Move dentry_kill() below lock_parent() John Ogness
2018-02-22 23:50 ` [PATCH v2 3/6] fs/dcache: Avoid the try_lock loop in d_delete() John Ogness
2018-02-23 2:08 ` Al Viro
2018-02-22 23:50 ` [PATCH v2 4/6] fs/dcache: Avoid the try_lock loops in dentry_kill() John Ogness
2018-02-23 2:22 ` Al Viro
2018-02-23 3:12 ` Al Viro
2018-02-23 3:16 ` Al Viro
2018-02-23 5:46 ` Al Viro
2018-02-22 23:50 ` [PATCH v2 5/6] fs/dcache: Avoid a try_lock loop in shrink_dentry_list() John Ogness
2018-02-23 3:48 ` Al Viro
2018-02-22 23:50 ` [PATCH v2 6/6] fs/dcache: Avoid remaining " John Ogness
2018-02-23 3:58 ` Al Viro
2018-02-23 4:08 ` Al Viro
2018-02-23 13:57 ` John Ogness
2018-02-23 15:09 ` Al Viro
2018-02-23 17:42 ` Al Viro
2018-02-23 20:13 ` [BUG] lock_parent() breakage when used from shrink_dentry_list() (was Re: [PATCH v2 6/6] fs/dcache: Avoid remaining try_lock loop in shrink_dentry_list()) Al Viro
2018-02-23 21:35 ` Linus Torvalds
2018-02-24 0:22 ` Al Viro
2018-02-25 7:40 ` Al Viro
2018-02-27 5:16 ` dcache: remove trylock loops (was Re: [BUG] lock_parent() breakage when used from shrink_dentry_list()) John Ogness
2018-03-12 19:13 ` Al Viro
2018-03-12 20:05 ` Al Viro
2018-03-12 20:33 ` Al Viro
2018-03-13 1:12 ` NeilBrown
2018-04-28 0:10 ` Al Viro [this message]
2018-03-12 20:23 ` Eric W. Biederman
2018-03-12 20:39 ` Al Viro
2018-03-12 23:28 ` Eric W. Biederman
2018-03-12 23:52 ` Eric W. Biederman
2018-03-13 0:37 ` Al Viro
2018-03-13 0:50 ` Al Viro
2018-03-13 4:02 ` Eric W. Biederman
2018-03-14 23:20 ` [PATCH] fs: Teach path_connected to handle nfs filesystems with multiple roots Eric W. Biederman
2018-03-15 22:34 ` Al Viro
2018-03-13 0:36 ` dcache: remove trylock loops (was Re: [BUG] lock_parent() breakage when used from shrink_dentry_list()) Al Viro
2018-03-12 22:14 ` Thomas Gleixner
2018-03-13 20:46 ` John Ogness
2018-03-13 21:05 ` John Ogness
2018-03-13 23:59 ` Al Viro
2018-03-14 2:58 ` Matthew Wilcox
2018-03-14 8:18 ` John Ogness
2018-03-02 9:04 ` [BUG] lock_parent() breakage when used from shrink_dentry_list() (was Re: [PATCH v2 6/6] fs/dcache: Avoid remaining try_lock loop in shrink_dentry_list()) Sebastian Andrzej Siewior
2018-02-23 0:59 ` [PATCH v2 0/6] fs/dcache: avoid trylock loops Linus Torvalds
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=20180428001003.GA14907@ZenIV.linux.org.uk \
--to=viro@zeniv.linux.org.uk \
--cc=bigeasy@linutronix.de \
--cc=ebiederm@xmission.com \
--cc=hch@lst.de \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=neilb@suse.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.