From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: [Patch v3 3/3] binfmt_misc: add F option description to documentation Date: Thu, 31 Mar 2016 07:57:10 -0700 Message-ID: <1459436230.2958.24.camel@HansenPartnership.com> References: <1459436046.2958.21.camel@HansenPartnership.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1459436046.2958.21.camel-d9PhHud1JfjCXq6kfMZ53/egYHeGw8Jk@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-fsdevel Cc: Jan Kara , Al Viro List-Id: containers.vger.kernel.org Signed-off-by: James Bottomley --- Documentation/binfmt_misc.txt | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/Documentation/binfmt_misc.txt b/Documentation/binfmt_misc.txt index 6b1de70..ec83bbc 100644 --- a/Documentation/binfmt_misc.txt +++ b/Documentation/binfmt_misc.txt @@ -66,6 +66,13 @@ Here is what the fields mean: This feature should be used with care as the interpreter will run with root permissions when a setuid binary owned by root is run with binfmt_misc. + 'F' - fix binary. The usual behaviour of binfmt_misc is to spawn the + binary lazily when the misc format file is invoked. However, + this doesn't work very well in the face of mount namespaces and + changeroots, so the F mode opens the binary as soon as the + emulation is installed and uses the opened image to spawn the + emulator, meaning it is always available once installed, + regardless of how the environment changes. There are some restrictions: -- 2.6.2 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bedivere.hansenpartnership.com ([66.63.167.143]:55106 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757292AbcCaO5L (ORCPT ); Thu, 31 Mar 2016 10:57:11 -0400 Message-ID: <1459436230.2958.24.camel@HansenPartnership.com> Subject: [Patch v3 3/3] binfmt_misc: add F option description to documentation From: James Bottomley To: containers@lists.linux-foundation.org, linux-fsdevel Cc: Al Viro , Jan Kara Date: Thu, 31 Mar 2016 07:57:10 -0700 In-Reply-To: <1459436046.2958.21.camel@HansenPartnership.com> References: <1459436046.2958.21.camel@HansenPartnership.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Signed-off-by: James Bottomley --- Documentation/binfmt_misc.txt | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/Documentation/binfmt_misc.txt b/Documentation/binfmt_misc.txt index 6b1de70..ec83bbc 100644 --- a/Documentation/binfmt_misc.txt +++ b/Documentation/binfmt_misc.txt @@ -66,6 +66,13 @@ Here is what the fields mean: This feature should be used with care as the interpreter will run with root permissions when a setuid binary owned by root is run with binfmt_misc. + 'F' - fix binary. The usual behaviour of binfmt_misc is to spawn the + binary lazily when the misc format file is invoked. However, + this doesn't work very well in the face of mount namespaces and + changeroots, so the F mode opens the binary as soon as the + emulation is installed and uses the opened image to spawn the + emulator, meaning it is always available once installed, + regardless of how the environment changes. There are some restrictions: -- 2.6.2