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
| ||
|
Date: Fri, 17 Apr 2009 01:05:15 +0100 From: Al Viro <viro@...IV.linux.org.uk> To: Christoph Hellwig <hch@...radead.org> Cc: Ingo Molnar <mingo@...e.hu>, Alexander Viro <viro@....linux.org.uk>, Alessio Igor Bogani <abogani@...ware.it>, Frederic Weisbecker <fweisbec@...il.com>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, LKML <linux-kernel@...r.kernel.org>, Jonathan Corbet <corbet@....net> Subject: Re: [PATCH -tip] remove the BKL: Replace BKL in mount/umount syscalls with a mutex On Thu, Apr 16, 2009 at 01:01:50PM -0400, Christoph Hellwig wrote: > ->remount_fs should be easy enough to, we do have proper per-sb > protection here, but do_remount_sb will need a bit of an audit. > (and of course pushing lock_kernel down into the many instances and > leave the cleanup-work to the fs maintainers). > > The actual mount path is more interesting as there are quite a few cases > there. As a first step you can take lock_kernel from outside do_mount > into the various do_foo calls inside it, and then work on those piece > by piece. The only place that might care is ->get_sb() (i.e. old ->read_super()). And only for protection of fs-type-wide data structures inside the fs/foo/* - anything in VFS doesn't give a damn (e.g. a realistic candidate might be something that maintains a private list of all sb->s_fs_info for this type and doesn't bother to do any locking, relying on BKL for all manipulations). ->write_super() and ->put_super() are other candidates, for the same reason. That's where BKL is generic_shutdown is coming from. Note that while we do have other users of do_kern_mount(), they tend to be limited to subset of fs types, so again, do not assume that "we use do_kern_mount() without BKL anyway" means that we are safe on that path. I'd suggest pushing that crap down into individual filesystems again. They *ARE* serialized for given superblock, so we really are looking for cross-fs-instance data structures. -- 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/
Powered by blists - more mailing lists