All of lore.kernel.org
 help / color / mirror / Atom feed
From: Jan Kara <jack@suse.cz>
To: Yann Droneaud <ydroneaud@opteya.com>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Eric Paris <eparis@redhat.com>,
	Richard Guy Briggs <rgb@redhat.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	stable@vger.kernel.org, linux-api@vger.kernel.org,
	Jan Kara <jack@suse.cz>, Lino Sanfilippo <LinoSanfilippo@gmx.de>,
	Valdis Kletnieks <Valdis.Kletnieks@vt.edu>,
	Michael Kerrisk-manpages <mtk.manpages@gmail.com>
Subject: Re: [PATCHv8.1] fanotify: enable close-on-exec on events' fd when requested in fanotify_init()
Date: Mon, 29 Sep 2014 13:50:23 +0200	[thread overview]
Message-ID: <20140929115023.GB6328@quack.suse.cz> (raw)
In-Reply-To: <1411980555-10818-1-git-send-email-ydroneaud@opteya.com>

On Mon 29-09-14 10:49:15, Yann Droneaud wrote:
> According to commit 80af258867648 ('fanotify: groups can specify
> their f_flags for new fd'), file descriptors created as part of
> file access notification events inherit flags from the
> event_f_flags argument passed to syscall fanotify_init(2).
> 
> So while it is legal for userspace to call fanotify_init() with
> O_CLOEXEC as part of its second argument, O_CLOEXEC is currently
> silently ignored.
> 
> Indeed event_f_flags are only given to dentry_open(), which only
> seems to care about O_ACCMODE and O_PATH in do_dentry_open(),
> O_DIRECT in open_check_o_direct() and O_LARGEFILE in
> generic_file_open().
> 
> But it seems logical to set close-on-exec flag on the file
> descriptor if userspace is allowed to request it with O_CLOEXEC.
> 
> In fact, according to some lookup on http://codesearch.debian.net/
> and various search engine, there's already some userspace code
> requesting it:
> 
> - in systemd's readahead[2]:
> 
>     fanotify_fd = fanotify_init(FAN_CLOEXEC|FAN_NONBLOCK, O_RDONLY|O_LARGEFILE|O_CLOEXEC|O_NOATIME);
> 
> - in clsync[3]:
> 
>     #define FANOTIFY_EVFLAGS (O_LARGEFILE|O_RDONLY|O_CLOEXEC)
> 
>     int fanotify_d = fanotify_init(FANOTIFY_FLAGS, FANOTIFY_EVFLAGS);
> 
> - in examples [4] from "Filesystem monitoring in the Linux
>   kernel" article[5] by Aleksander Morgado:
> 
>     if ((fanotify_fd = fanotify_init (FAN_CLOEXEC,
>                                       O_RDONLY | O_CLOEXEC | O_LARGEFILE)) < 0)
> 
> Lookup also returned some wrong usage of the syscall:
> 
> - in Gonk HAL from Mozilla Firefox OS sources[6]:
> 
>     mFd = fanotify_init(FAN_CLASS_NOTIF, FAN_CLOEXEC);
> 
> Adding support for O_CLOEXEC in fanotify_init() won't magically
> enable it for Gonk since FAN_CLOEXEC is defined as 0x1, which
> is likely equal to O_WRONLY when used in open flag context. In
> the other hand, it won't hurt it either.
> 
> So this patch replaces call to macro get_unused_fd() by a call
> to function get_unused_fd_flags() with event_f_flags value as
> argument. This way O_CLOEXEC flag in the second argument of
> fanotify_init(2) syscall is interpreted so that close-on-exec
> get enabled when requested.
> 
> [1] http://blog.ffwll.ch/2013/11/botching-up-ioctls.html
> [2] http://cgit.freedesktop.org/systemd/systemd/tree/src/readahead/readahead-collect.c?id=v208#n294
> [3] https://github.com/xaionaro/clsync/blob/v0.2.1/sync.c#L1631
>     https://github.com/xaionaro/clsync/blob/v0.2.1/configuration.h#L38
> [4] http://www.lanedo.com/~aleksander/fanotify/fanotify-example.c
> [5] http://www.lanedo.com/2013/filesystem-monitoring-linux-kernel/
> [6] http://hg.mozilla.org/mozilla-central/file/325c74addeba/hal/gonk/GonkDiskSpaceWatcher.cpp#l167
> 
> Link: http://lkml.kernel.org/r/cover.1394532336.git.ydroneaud@opteya.com
> Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
> Cc: Michael Kerrisk-manpages <mtk.manpages@gmail.com>
> Cc: Lino Sanfilippo <LinoSanfilippo@gmx.de>
> Cc: Richard Guy Briggs <rgb@redhat.com>
> Cc: Eric Paris <eparis@redhat.com>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: stable@vger.kernel.org
> Cc: linux-api@vger.kernel.org
> Reviewed by: Heinrich Schuchardt <xypron.glpk@gmx.de>
> Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
  The patch looks good. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
> Hi Andrew and Henrich,
> 
> Please find an updated patch with a commit message fixed regarding
> the obsolote comments on code which is now updated, thanks to
> Heinrich's patch.
> 
> Changes from v8:
> - fixed commit message
> - added Reviewed-by:
> 
> Regards.
> 
> Yann Droneaud,
> OPTEYA
> 
>  fs/notify/fanotify/fanotify_user.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index b13992a41bd9..c991616acca9 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -78,7 +78,7 @@ static int create_fd(struct fsnotify_group *group,
>  
>  	pr_debug("%s: group=%p event=%p\n", __func__, group, event);
>  
> -	client_fd = get_unused_fd();
> +	client_fd = get_unused_fd_flags(group->fanotify_data.f_flags);
>  	if (client_fd < 0)
>  		return client_fd;
>  
> -- 
> 1.9.3
> 
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

  reply	other threads:[~2014-09-29 11:51 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-24 13:11 [PATCHv8 0/6] Getting rid of get_unused_fd() / enable close-on-exec Yann Droneaud
2014-09-24 13:11 ` Yann Droneaud
2014-09-24 13:11 ` Yann Droneaud
2014-09-24 13:11 ` [PATCHv8 1/6] fanotify: enable close-on-exec on events' fd when requested in fanotify_init() Yann Droneaud
2014-09-25 20:57   ` Heinrich Schuchardt
2014-09-25 20:57     ` Heinrich Schuchardt
2014-09-26  8:58     ` Yann Droneaud
2014-09-27  7:26       ` Heinrich Schuchardt
2014-09-29  8:49         ` [PATCHv8.1] " Yann Droneaud
2014-09-29 11:50           ` Jan Kara [this message]
2014-10-01 22:36           ` Andrew Morton
2014-10-01 22:36             ` Andrew Morton
2014-10-02  6:20             ` Yann Droneaud
2014-10-02  6:50               ` Mihai Donțu
2014-10-02  7:52               ` [PATCH] fanotify: add a flag to allow setting O_CLOEXEC on event fd Yann Droneaud
2014-10-02  9:13                 ` Pádraig Brady
2014-10-02  9:13                   ` Pádraig Brady
2014-10-02  9:13                   ` Pádraig Brady
2014-10-02 11:55                   ` Michael Kerrisk (man-pages)
2014-10-02 14:44                   ` Yann Droneaud
2014-10-02 14:44                     ` Yann Droneaud
2014-10-02 10:44             ` [PATCHv8.1] fanotify: enable close-on-exec on events' fd when requested in fanotify_init() Jan Kara
2014-10-02 10:44               ` Jan Kara
2014-10-02 19:46               ` Andrew Morton
2014-10-02 19:46                 ` Andrew Morton
2014-10-03  8:39                 ` [PATCHv8.2] " Yann Droneaud
2014-10-03  8:39                   ` Yann Droneaud
2014-09-24 13:11 ` [PATCHv8 2/6] ia64: trivial: replace get_unused_fd() by get_unused_fd_flags(0) Yann Droneaud
2014-09-24 13:11 ` [PATCHv8 3/6] ppc/cell: " Yann Droneaud
2014-09-24 13:11   ` Yann Droneaud
2014-09-24 13:11 ` [PATCHv8 4/6] binfmt_misc: " Yann Droneaud
2014-09-24 13:11 ` [PATCHv8 5/6] file: " Yann Droneaud
2014-09-24 13:11 ` [PATCHv8 6/6] file: remove get_unused_fd() macro Yann Droneaud

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=20140929115023.GB6328@quack.suse.cz \
    --to=jack@suse.cz \
    --cc=LinoSanfilippo@gmx.de \
    --cc=Valdis.Kletnieks@vt.edu \
    --cc=akpm@linux-foundation.org \
    --cc=eparis@redhat.com \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mtk.manpages@gmail.com \
    --cc=rgb@redhat.com \
    --cc=stable@vger.kernel.org \
    --cc=viro@zeniv.linux.org.uk \
    --cc=xypron.glpk@gmx.de \
    --cc=ydroneaud@opteya.com \
    --subject='Re: [PATCHv8.1] fanotify: enable close-on-exec on events'\'' fd when requested in fanotify_init()' \
    /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

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.