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Groups > linux.kernel > #1633360

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

From Andy Lutomirski <luto@kernel.org>
Newsgroups linux.kernel
Subject Re: new ...at() flag: AT_NO_JUMPS
Date 2017-04-30 01:20 +0200
Message-ID <tBJOF-3ZL-1@gated-at.bofh.it> (permalink)
References <tBIIW-3pv-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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 "../.."?

> Right now I have it hooked only for fstatat() and friends; it could be
> easily extended to any ...at() syscalls.  Objections?

I like it, assuming the answers to all the questions above are that
they will be rejected.

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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

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