From: Andy Lutomirski <luto@kernel.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>,
Linux API <linux-api@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>
Subject: Re: new ...at() flag: AT_NO_JUMPS
Date: Sat, 29 Apr 2017 18:13:27 -0700 [thread overview]
Message-ID: <CALCETrVue8VyJDUSgy9Hsw67mxddirwDr703OBM_fWm9Hzvb4A@mail.gmail.com> (raw)
In-Reply-To: <20170429232504.GU29622@ZenIV.linux.org.uk>
On Sat, Apr 29, 2017 at 4:25 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Sat, Apr 29, 2017 at 04:17:18PM -0700, Andy Lutomirski wrote:
>> On Sat, Apr 29, 2017 at 3:04 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
>> > New AT_... flag - AT_NO_JUMPS
>> >
>> > Semantics: pathname resolution must not involve
>> > * traversals of absolute symlinks
>> > * traversals of procfs-style symlinks
>> > * traversals of mountpoints (including bindings, referrals, etc.)
>> > * traversal of .. in the starting point of pathname resolution.
>>
>> Can you clarify this last one? I assume that ".." will be rejected,
>> but what about "a/../.."? How about "b" if b is a symlink to ".."?
>> How about "a/b" if a is a directory and b is a symlink to "../.."?
>
> All of those will be rejected - in each of those cases pathname traversal
> leads back into the starting point with .. being the next component to
> handle.
Sounds good.
Might it make sense to split it into two flags, one to prevent moving
between mounts and one for everything else? I can imagine webservers
and such that are fine with traversing mount points but don't want to
escape their home directory.
--Andy
next prev parent reply other threads:[~2017-04-30 1:13 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 [this message]
[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
[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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