From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman)
To: Al Viro <viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
Cc: Greg Kroah-Hartman
<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
Kay Sievers <kay.sievers-tD+1rO4QERM@public.gmane.org>,
Dave Hansen <haveblue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Andy Whitcroft <apw-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>,
sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org,
Linus Torvalds
<torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
Alan Cox <alan-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
Subject: Re: [PATCH 3/4] devpts: Make the newinstance option historical
Date: Sun, 23 Sep 2012 00:00:19 -0700 [thread overview]
Message-ID: <87pq5d441o.fsf@xmission.com> (raw)
In-Reply-To: <20120923063445.GA26640-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org> (Al Viro's message of "Sun, 23 Sep 2012 07:34:45 +0100")
Al Viro <viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org> writes:
> On Sun, Sep 23, 2012 at 07:30:38AM +0100, Al Viro wrote:
>> On Sat, Sep 22, 2012 at 10:59:04PM -0700, Eric W. Biederman wrote:
>>
>> > The test:
>> > >> + if (filp->f_vfsmnt->mnt_root == filp->f_dentry)
>> > kicks in and no redirection is performed.
>>
>> Umm... OK, after the first round of recursion. Unless you bind /something/pts
>> on /something.
>
> Other way round, of course... E.g.
> mount --bind /dev /dev/pts
> mount --bind /dev /dev/pts/pts
> etc. enough times to overflow the kernel stack on recursion.
Except of course I gave the wrong explanation.
I did the open with O_PATH. Since O_PATH never calls open recursion
is impossible.
Eric
WARNING: multiple messages have this Message-ID (diff)
From: ebiederm@xmission.com (Eric W. Biederman)
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Kay Sievers <kay.sievers@vrfy.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
containers@lists.linux-foundation.org,
Dave Hansen <haveblue@us.ibm.com>,
linux-kernel@vger.kernel.org, Andy Whitcroft <apw@canonical.com>,
sukadev@linux.vnet.ibm.com,
Linus Torvalds <torvalds@linux-foundation.org>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
Serge Hallyn <serge.hallyn@canonical.com>
Subject: Re: [PATCH 3/4] devpts: Make the newinstance option historical
Date: Sun, 23 Sep 2012 00:00:19 -0700 [thread overview]
Message-ID: <87pq5d441o.fsf@xmission.com> (raw)
In-Reply-To: <20120923063445.GA26640@ZenIV.linux.org.uk> (Al Viro's message of "Sun, 23 Sep 2012 07:34:45 +0100")
Al Viro <viro@ZenIV.linux.org.uk> writes:
> On Sun, Sep 23, 2012 at 07:30:38AM +0100, Al Viro wrote:
>> On Sat, Sep 22, 2012 at 10:59:04PM -0700, Eric W. Biederman wrote:
>>
>> > The test:
>> > >> + if (filp->f_vfsmnt->mnt_root == filp->f_dentry)
>> > kicks in and no redirection is performed.
>>
>> Umm... OK, after the first round of recursion. Unless you bind /something/pts
>> on /something.
>
> Other way round, of course... E.g.
> mount --bind /dev /dev/pts
> mount --bind /dev /dev/pts/pts
> etc. enough times to overflow the kernel stack on recursion.
Except of course I gave the wrong explanation.
I did the open with O_PATH. Since O_PATH never calls open recursion
is impossible.
Eric
next prev parent reply other threads:[~2012-09-23 7:00 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-24 0:05 [RFC] fix devpts mount behavior Serge Hallyn
2012-01-24 0:05 ` Serge Hallyn
2012-01-24 0:13 ` Linus Torvalds
2012-01-24 0:13 ` Linus Torvalds
[not found] ` <CA+55aFz9ofF+Ey8VCDS8UEf2XSw36kj2RhkHfFScuzLXMeNrkA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-01-24 0:25 ` Serge Hallyn
2012-01-24 0:25 ` Serge Hallyn
2012-01-24 0:41 ` Linus Torvalds
2012-01-24 0:41 ` Linus Torvalds
[not found] ` <CA+55aFzwOU137V6wtyBjessx05NJo2G4KV0rvTKWvC79A+o9iQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-01-24 1:07 ` Al Viro
2012-01-24 1:07 ` Al Viro
[not found] ` <20120124010758.GJ23916-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2012-01-24 18:21 ` Serge E. Hallyn
2012-01-24 18:21 ` Serge E. Hallyn
2012-01-24 20:16 ` Sukadev Bhattiprolu
[not found] ` <20120124201600.GB20039-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2012-01-24 20:53 ` Serge E. Hallyn
2012-01-24 20:53 ` Serge E. Hallyn
[not found] ` <20120124182116.GA11715-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>
2012-01-24 20:16 ` Sukadev Bhattiprolu
2012-01-24 20:24 ` Eric W. Biederman
2012-01-24 20:24 ` Eric W. Biederman
[not found] ` <m1k44gj1cu.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2012-01-24 22:02 ` Serge E. Hallyn
2012-01-24 22:02 ` Serge E. Hallyn
[not found] ` <20120124220247.GA26353-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>
2012-01-24 22:54 ` Kay Sievers
2012-01-24 22:54 ` Kay Sievers
[not found] ` <CAPXgP13_gczQmG_USAp0p2AuTfxkzAvzHvjbZY_rbbLH-4rDyg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-01-24 23:16 ` Serge Hallyn
2012-01-24 23:16 ` Serge Hallyn
2012-01-24 23:25 ` Sukadev Bhattiprolu
2012-01-24 23:25 ` Sukadev Bhattiprolu
[not found] ` <20120124232502.GA22218-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2012-01-24 23:29 ` Serge E. Hallyn
2012-01-24 23:29 ` Serge E. Hallyn
2012-01-24 23:27 ` Kay Sievers
2012-01-24 23:27 ` Kay Sievers
[not found] ` <CAPXgP12REAwmDORzdGJhsxZKU8nhiauCxoVdKa8Eifw4MWWtgA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-01-28 19:51 ` Serge Hallyn
2012-01-28 19:51 ` Serge Hallyn
2012-01-28 20:52 ` Eric W. Biederman
2012-01-28 20:52 ` Eric W. Biederman
[not found] ` <m139azpn2n.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2012-01-28 21:32 ` Kay Sievers
2012-01-28 21:32 ` Kay Sievers
2012-09-23 3:47 ` [PATCH 0/4] devpts: " Eric W. Biederman
2012-09-23 3:47 ` Eric W. Biederman
[not found] ` <87txup763i.fsf_-_-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2012-09-23 3:48 ` [PATCH 1/4] devpts: Remove CONFIG_DEVPTS_MULTIPLE_INSTANCES Eric W. Biederman
2012-09-23 3:48 ` Eric W. Biederman
2012-09-23 3:49 ` [PATCH 2/4] devpts: Set the default permissions of /dev/pts/ptmx and /dev/ptmx to 0666 Eric W. Biederman
2012-09-23 3:49 ` Eric W. Biederman
2012-09-23 3:50 ` [PATCH 3/4] devpts: Make the newinstance option historical Eric W. Biederman
2012-09-23 3:50 ` Eric W. Biederman
[not found] ` <87d31d75yj.fsf_-_-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2012-09-23 4:19 ` Al Viro
2012-09-23 4:19 ` Al Viro
[not found] ` <20120923041906.GM13973-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2012-09-23 4:46 ` Al Viro
2012-09-23 4:46 ` Al Viro
2012-09-23 5:59 ` Eric W. Biederman
2012-09-23 5:59 ` Eric W. Biederman
[not found] ` <87bogx5lg7.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2012-09-23 6:30 ` Al Viro
2012-09-23 6:30 ` Al Viro
[not found] ` <20120923063038.GO13973-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2012-09-23 6:34 ` Al Viro
2012-09-23 6:34 ` Al Viro
[not found] ` <20120923063445.GA26640-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2012-09-23 7:00 ` Eric W. Biederman [this message]
2012-09-23 7:00 ` Eric W. Biederman
2012-09-23 3:51 ` [PATCH 4/4] devpts: Update the documentation Eric W. Biederman
2012-09-23 3:51 ` Eric W. Biederman
2012-09-23 16:48 ` [PATCH 0/4] devpts: fix devpts mount behavior H. Peter Anvin
2012-09-23 16:48 ` H. Peter Anvin
[not found] ` <505F3D48.7080103-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
2012-09-23 17:42 ` Eric W. Biederman
2012-09-23 17:42 ` Eric W. Biederman
[not found] ` <87txuo3abb.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2012-09-23 17:44 ` H. Peter Anvin
2012-09-23 17:44 ` H. Peter Anvin
2012-01-24 23:35 ` [RFC] " Eric W. Biederman
2012-01-24 23:35 ` Eric W. Biederman
2012-01-24 20:55 ` Sukadev Bhattiprolu
2012-01-24 20:55 ` Sukadev Bhattiprolu
[not found] ` <20120124205502.GC20039-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2012-01-24 21:19 ` Nick Bowler
2012-01-24 21:19 ` Nick Bowler
2012-01-24 0:26 ` Al Viro
2012-01-24 0:26 ` Al Viro
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