Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1636113

Re: new ...at() flag: AT_NO_JUMPS

Show all headers | View raw

On Thu, May 4, 2017 at 5:30 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> As for mountpoint crossing...  it might make sense to split those.
> O_BENEATH allowed it, and if we want AT_BENEATH to match that - let's
> do it.  Then this one would become AT_BENEATH | AT_XDEV (the latter named
> after find(1) option, obviously).

So I would still like to split that NO_JUMP flag even more.

I like the AT_BENEATH | AT_XDEV split, but I think XDEV should be
split further, and I think the symlink avoidance should be split more
too.

As mentioned last time, at least for the git usage, even relative
symlinks are a no-no - not because they'd escape, but simply because
git wants to see the *unique* name, and resolve relative symlinks to
either the symlink, or to the actual file it points to.

So I think that we'd want an additional flag that says "no symlinks at all".

And I think the "no mountpoint" traversal might be splittable too.

Yes, sometimes you'd probably want to say "stay exactly inside this
filesystem" (like find -xdev). So no arguments against AT_XDEV that
refuses any mount traversal (kind of like my "no symlink traversal"
thing).

But at other points you might want to just guarantee that the walk
stays below a certain starting point and doesn't escape.

That could still allow crossing mount-points, but only if they are
non-bind mounts and cannot let us escape.

I'm not sure if that's testable, though.

                  Linus

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

new ...at() flag: AT_NO_JUMPS Al Viro <viro@ZenIV.linux.org.uk> - 2017-04-30 00:10 +0200
  Re: new ...at() flag: AT_NO_JUMPS Andy Lutomirski <luto@kernel.org> - 2017-04-30 01:20 +0200
    Re: new ...at() flag: AT_NO_JUMPS Al Viro <viro@ZenIV.linux.org.uk> - 2017-04-30 01:30 +0200
      Re: new ...at() flag: AT_NO_JUMPS Andy Lutomirski <luto@kernel.org> - 2017-04-30 03:20 +0200
      Re: new ...at() flag: AT_NO_JUMPS Matthew Wilcox <willy@infradead.org> - 2017-04-30 06:40 +0200
        Re: new ...at() flag: AT_NO_JUMPS Al Viro <viro@ZenIV.linux.org.uk> - 2017-04-30 18:20 +0200
          Re: new ...at() flag: AT_NO_JUMPS Andy Lutomirski <luto@kernel.org> - 2017-05-01 07:00 +0200
            Re: new ...at() flag: AT_NO_JUMPS Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-01 07:20 +0200
  Re: new ...at() flag: AT_NO_JUMPS Jann Horn <jannh@google.com> - 2017-05-01 19:40 +0200
    Re: new ...at() flag: AT_NO_JUMPS Andy Lutomirski <luto@kernel.org> - 2017-05-01 21:40 +0200
    Re: new ...at() flag: AT_NO_JUMPS Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-05 02:40 +0200
      Re: new ...at() flag: AT_NO_JUMPS Andy Lutomirski <luto@kernel.org> - 2017-05-05 02:50 +0200
        Re: new ...at() flag: AT_NO_JUMPS Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-05 03:10 +0200
      Re: new ...at() flag: AT_NO_JUMPS Linus Torvalds <torvalds@linux-foundation.org> - 2017-05-05 03:30 +0200
        Re: new ...at() flag: AT_NO_JUMPS Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-05 05:10 +0200
          Re: new ...at() flag: AT_NO_JUMPS Linus Torvalds <torvalds@linux-foundation.org> - 2017-05-05 06:10 +0200
            Re: new ...at() flag: AT_NO_JUMPS Andy Lutomirski <luto@kernel.org> - 2017-05-05 06:40 +0200
      Re: new ...at() flag: AT_NO_JUMPS Jann Horn <jannh@google.com> - 2017-05-05 04:50 +0200
        Re: new ...at() flag: AT_NO_JUMPS Linus Torvalds <torvalds@linux-foundation.org> - 2017-05-05 05:50 +0200
          Re: new ...at() flag: AT_NO_JUMPS Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-05 06:40 +0200
            Re: new ...at() flag: AT_NO_JUMPS Andy Lutomirski <luto@kernel.org> - 2017-05-05 06:50 +0200
              Re: new ...at() flag: AT_NO_JUMPS ebiederm@xmission.com (Eric W. Biederman) - 2017-05-05 22:20 +0200
            Re: new ...at() flag: AT_NO_JUMPS ebiederm@xmission.com (Eric W. Biederman) - 2017-05-05 22:40 +0200
              Re: new ...at() flag: AT_NO_JUMPS Mickaël Salaün <mic@digikod.net> - 2017-05-08 21:40 +0200

csiph-web