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From: Miklos Szeredi <mszeredi@redhat.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Christoph Hellwig <hch@infradead.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 05/12] f*xattr: allow O_PATH descriptors
Date: Thu, 14 May 2020 15:01:13 +0200	[thread overview]
Message-ID: <CAOssrKeV7g0wPg4ozspG4R7a+5qARqWdG+GxWtXB-MCfbVM=9A@mail.gmail.com> (raw)
In-Reply-To: <CAJfpeguPhJApOQgw02-yCPJZ5Tx_Zy2ZFh+De5DC560FNqdFSA@mail.gmail.com>

On Thu, May 14, 2020 at 10:02 AM Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> On Wed, May 13, 2020 at 12:04 PM Christoph Hellwig <hch@infradead.org> wrote:
> >
> > Needs a Cc to linux-api and linux-man.
> >
> > On Tue, May 05, 2020 at 11:59:08AM +0200, Miklos Szeredi wrote:
> > > This allows xattr ops on symlink/special files referenced by an O_PATH
> > > descriptor without having to play games with /proc/self/fd/NN (which
> > > doesn't work for symlinks anyway).
> >
> > Do we even intent to support xattrs on say links?  They never wire up
> > ->listxattr and would only get them through s_xattr.  I'm defintively
> > worried that this could break things without a very careful audit.
>
> Why do you think listxattr is not wired up for symlinks?
>
> Xfs and ext4 definitely do have it, and it seems most others too:
>
> $ git grep -A10  "struct inode_operations.*symlink" | grep listxattr | wc -l
> 29

In any case, I'm dropping this patch for now.   The comment about
/proc/self/fd/NN not working is actually wrong; it does work despite
the target being a symlink: LOOKUP_FOLLOW only follows the magic
symlink in this case, not the symlink that is the target.  So it's
possible to get (set, remove, list) the xattr on an O_PATH descriptor
using

sprintf("/proc/self/fd/%i", procpath, sizeof(procpath));
getxattr(procpath, ...);

Thanks,
Miklos


  reply	other threads:[~2020-05-14 13:01 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-05  9:59 [PATCH 00/12] vfs patch queue Miklos Szeredi
2020-05-05  9:59 ` [PATCH 01/12] vfs: allow unprivileged whiteout creation Miklos Szeredi
2020-05-13 19:12   ` Al Viro
2020-05-05  9:59 ` [PATCH 02/12] aio: fix async fsync creds Miklos Szeredi
2020-05-13 10:01   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 03/12] proc/mounts: add cursor Miklos Szeredi
2020-05-13 19:33   ` Al Viro
2020-05-05  9:59 ` [PATCH 04/12] utimensat: AT_EMPTY_PATH support Miklos Szeredi
2020-05-13 10:02   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 05/12] f*xattr: allow O_PATH descriptors Miklos Szeredi
2020-05-13 10:04   ` Christoph Hellwig
2020-05-14  8:02     ` Miklos Szeredi
2020-05-14 13:01       ` Miklos Szeredi [this message]
2020-05-05  9:59 ` [PATCH 06/12] uapi: deprecate STATX_ALL Miklos Szeredi
2020-05-13 10:04   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 07/12] statx: don't clear STATX_ATIME on SB_RDONLY Miklos Szeredi
2020-05-13 10:04   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 08/12] statx: add mount ID Miklos Szeredi
2020-05-13 10:05   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 09/12] statx: add mount_root Miklos Szeredi
2020-05-05 14:24   ` J . Bruce Fields
2020-05-13 10:05   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 10/12] vfs: don't parse forbidden flags Miklos Szeredi
2020-05-13 10:06   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 11/12] vfs: don't parse "posixacl" option Miklos Szeredi
2020-05-13 10:07   ` Christoph Hellwig
2020-05-05  9:59 ` [PATCH 12/12] vfs: don't parse "silent" option Miklos Szeredi
2020-05-13 10:07   ` Christoph Hellwig
2020-05-13  7:45 ` [13/12 PATCH] vfs: add faccessat2 syscall Miklos Szeredi
2020-05-13 10:09   ` Christoph Hellwig
2020-05-13  7:47 ` [PATCH 00/12] vfs patch queue Miklos Szeredi
2020-05-13 19:48   ` Al Viro
2020-05-14 11:46     ` Miklos Szeredi
2020-05-14 14:55     ` Miklos Szeredi
2020-05-14 15:10       ` Al Viro

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