linux-kernel - [PATCH 0/2] avoid prepare_creds in faccessat when possible

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Date:	Mon,  9 Mar 2015 21:35:45 +0100
From:	Mateusz Guzik <mguzik@...hat.com>
To:	Alexander Viro <viro@...iv.linux.org.uk>,
	Serge Hallyn <serge.hallyn@...onical.com>
Cc:	Paul Moore <pmoore@...hat.com>, Eric Paris <eparis@...hat.com>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org
Subject: [PATCH 0/2] avoid prepare_creds in faccessat when possible

Sometimes faccessat needs to modify current thread's credentials, but
calls prepare_creds unconditionally.

However, typically resulting credentials are identical to original ones
and in that case newcredentials are unnecessary. We can detect this before
allocating anything.

This patch series adds a helper which allows comparing capability sets and
modifies faccessat to use it.

Mateusz Guzik (2):
  CAPABILITIES: add cap_isequal helper
  fs: avoid unnecessary prepare_creds in faccessat

 fs/open.c                  | 53 ++++++++++++++++++++++++++++++----------------
 include/linux/capability.h | 10 +++++++++
 2 files changed, 45 insertions(+), 18 deletions(-)

-- 
1.8.3.1

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