Hi,
Le jeudi 25 septembre 2014 à 22:57 +0200, Heinrich Schuchardt a écrit :
> On 24.09.2014 15:11, 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().
>
> I tested on kernel 3.17.0-rc5. I passed O_CLOEXEC in event_f_flags.
> When I called fcnt(event_metadata->fd, F_GETFD) it did not return
> FD_CLOEXEC. So I can confirm your observation that O_CLOEXEC is not
> working as expected.
>
> I found this definition
> #define get_unused_fd() get_unused_fd_flags(0)
>
> So essentially when get_unused_fd() is called for a fanotify event
> O_CLOEXEC is ignored.
>
> This is what your patch fixes.
>
> >
> > More, there's no effective check on event_f_flags value that
> > would catch unknown / unsupported values, unlike the one on
> > f_flags argument of the syscall (see FAN_ALL_INIT_FLAGS in
> > include/uapi/linux/fanotify.h).
>
> The fanotify_init(2) man page describes which flags are allowable in
> event_f_flags.
>
> Could you, please, explain why the following code in fanotify_user.c is
> not to be considered an effective check:
>
> if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS)
> return -EINVAL;
>
> switch (event_f_flags & O_ACCMODE) {
> case O_RDONLY:
> case O_RDWR:
> case O_WRONLY:
> break;
> default:
> return -EINVAL;
> }
>
> I CC Jan Kara as he reviewed the code.
>
I missed the opportunity to update my commit message.
I've sent my initial version of the patch (with the same wording) on
5th, January, 2014:
http://mid.gmane.org/3d9591f81e62a78a726721c8052b3910870db35e.1388952061.git.ydroneaud@xxxxxxxxxx
http://lkml.kernel.org/r/3d9591f81e62a78a726721c8052b3910870db35e.1388952061.git.ydroneaud@xxxxxxxxxx
The patch was sent again on March, 11:
http://lkml.kernel.org/r/baab31b572b216d13f2149bdf07e0f79a1bae660.1394532336.git.ydroneaud@xxxxxxxxxx
http://mid.gmane.org/baab31b572b216d13f2149bdf07e0f79a1bae660.1394532336.git.ydroneaud@xxxxxxxxxx
And another time, on June, 1st:
http://lkml.kernel.org/r/2c6ab28980f0007ea3b9afa7ecd7497806a6a451.1401630396.git.ydroneaud@xxxxxxxxxx
http://mid.gmane.org/2c6ab28980f0007ea3b9afa7ecd7497806a6a451.1401630396.git.ydroneaud@xxxxxxxxxx
So as you can see, my patch predate yours:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=48149e9d3a7e924010a0daab30a6197b7d7b6580
But I have to apologize: I haven't noticed your patch was merged between
my previous submission and the current one. My bad.
I will update the commit message to remove my obsolete comment on the
input parameter check.
Thanks again for review and testing.
Regards.
--
Yann Droneaud
OPTEYA
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