linux-kernel - [PATCH v2 0/3] Relocate execve() sanity checks

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Date:   Fri,  5 Jun 2020 09:00:10 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Kees Cook <keescook@...omium.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Aleksa Sarai <cyphar@...har.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Eric Biggers <ebiggers3@...il.com>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 0/3] Relocate execve() sanity checks

Hi,

While looking at the code paths for the proposed O_MAYEXEC flag, I saw
some things that looked like they should be fixed up.

  exec: Change uselib(2) IS_SREG() failure to EACCES
	This just regularizes the return code on uselib(2).

  exec: Move S_ISREG() check earlier
	This moves the S_ISREG() check even earlier than it was already.

  exec: Move path_noexec() check earlier
	This adds the path_noexec() check to the same place as the
	S_ISREG() check.

v2:
- move checks into may_open() using acc_mode instead of f_mode to correctly
  compose with other inode file type tests[1].
- drop the FMODE_EXEC f_flags -> f_mode change for now since it remains
  unclear if it's useful (and is not needed any more for this series).
v1: https://lore.kernel.org/linux-api/20200518055457.12302-1-keescook@chromium.org/

Thanks!

-Kees

[1] https://lore.kernel.org/lkml/202006041910.9EF0C602@keescook/

Kees Cook (3):
  exec: Change uselib(2) IS_SREG() failure to EACCES
  exec: Move S_ISREG() check earlier
  exec: Move path_noexec() check earlier

 fs/exec.c  | 23 ++++++++++++++---------
 fs/namei.c | 10 ++++++++--
 fs/open.c  |  6 ------
 3 files changed, 22 insertions(+), 17 deletions(-)

-- 
2.25.1