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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Jann Horn <jannh@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
	Linux API <linux-api@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	David Drysdale <drysdale@google.com>
Subject: Re: new ...at() flag: AT_NO_JUMPS
Date: Thu, 4 May 2017 20:46:49 -0700	[thread overview]
Message-ID: <CA+55aFy1SokNNUgxBnFLdA1PRyeG13BqyYNg5xVrW-tNGqh2Bg@mail.gmail.com> (raw)
In-Reply-To: <CAG48ez1jzNvxB+bfOBnERFGp=oMM0vHWuLD6EULmne3R6xa53w@mail.gmail.com>

On Thu, May 4, 2017 at 7:47 PM, Jann Horn <jannh@google.com> wrote:
>
> Thread 1 starts an AT_BENEATH path walk using an O_PATH fd
> pointing to /srv/www/example.org/foo; the path given to the syscall is
> "bar/../../../../etc/passwd". The path walk enters the "bar" directory.
> Thread 2 moves /srv/www/example.org/foo/bar to
> /srv/www/example.org/bar.
> Thread 1 processes the rest of the path ("../../../../etc/passwd"), never
> hitting /srv/www/example.org/foo in the process.
>
> I'm not really familiar with the VFS internals, but from a coarse look
> at the patch, it seems like it wouldn't block this?

I think you're right.

I guess it would be safe for the RCU case due to the sequence number
check, but not the non-RCU case.

Al?

                 Linus

  reply	other threads:[~2017-05-05  3:46 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-29 22:04 new ...at() flag: AT_NO_JUMPS Al Viro
     [not found] ` <20170429220414.GT29622-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-04-29 23:17   ` Andy Lutomirski
     [not found]     ` <CALCETrXhOhG0tRDDOROwT9ghvQvKziM2PBN=CX5Soa2m7=0cFw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-29 23:25       ` Al Viro
2017-04-30  1:13         ` Andy Lutomirski
     [not found]         ` <20170429232504.GU29622-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-04-30  4:38           ` Matthew Wilcox
     [not found]             ` <20170430043822.GE27790-PfSpb0PWhxZc2C7mugBRk2EX/6BAtgUQ@public.gmane.org>
2017-04-30 16:10               ` Al Viro
2017-05-01  4:52                 ` Andy Lutomirski
     [not found]                   ` <CALCETrX0dx3d6OQQ+1GJ_xgSz3iNVeRn+8o6b-+3f7awVOWdQg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-01  5:15                     ` Al Viro
2017-05-01 17:36 ` Jann Horn
2017-05-01 19:37   ` Andy Lutomirski
     [not found]   ` <CAG48ez0wccvQ5i+XN_Q_yA9_ZwSaGb-W+zky0KQb_GU=9G+MSw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-05  0:30     ` Al Viro
2017-05-05  0:44       ` Andy Lutomirski
2017-05-05  1:06         ` Al Viro
     [not found]       ` <20170505003030.GM29622-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-05  1:27         ` Linus Torvalds
     [not found]           ` <CA+55aFyOKM7DW7+0sdDFKdZFXgptb5r1id9=Wvhd8AgSP7qjwQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-05  3:00             ` Al Viro
2017-05-05  4:01               ` Linus Torvalds
2017-05-05  4:31                 ` Andy Lutomirski
2017-05-05  2:47       ` Jann Horn
2017-05-05  3:46         ` Linus Torvalds [this message]
     [not found]           ` <CA+55aFy1SokNNUgxBnFLdA1PRyeG13BqyYNg5xVrW-tNGqh2Bg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-05  4:39             ` Al Viro
2017-05-05  4:44               ` Andy Lutomirski
     [not found]                 ` <CALCETrVQ2fwDZOsGSoLyRb6Qjp4nszfDjOPSYi0kzqt23Aw1NA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-05 20:04                   ` Eric W. Biederman
2017-05-05 20:28               ` Eric W. Biederman
     [not found]                 ` <8737cj6oao.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-05-08 19:34                   ` Mickaël Salaün
2017-05-18  8:50       ` David Drysdale

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