[PATCH v3 00/15] exec: Use sane stack rlimit under secureexec

From	Kees Cook <keescook@chromium.org>
Newsgroups	linux.kernel
Subject	[PATCH v3 00/15] exec: Use sane stack rlimit under secureexec
Date	2017-07-19 00:30 +0200
Message-ID	<u4Ja9-8f4-3@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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This series has grown... :P

As discussed with Linus and Andy, we need to reset the stack rlimit
before we do memory layouts when execing a privilege-gaining (e.g.
setuid) program. To do this, we need to know the results of the
bprm_secureexec hook before memory layouts. As it turns out, this
can be made _mostly_ trivial by collapsing bprm_secureexec into
bprm_set_creds.

The LSMs using bprm_secureexec nearly always save state between
bprm_set_creds and bprm_secureexec. In the face of multiple calls to
bprm_set_creds (via prepare_binprm() calls from binfmt_script, etc),
all LSMs except commoncap only pay attention to the first call, so
that aligns well with collapsing bprm_secureexec into bprm_set_creds.
The commoncaps, though, needs to check the _last_ bprm_set_creds, so
this series just swaps one bprm flag for another (cap_effective is no
longer needed to save state between bprm_set_creds and bprm_secureexec,
but we do need to keep a separate state, so we add the cap_elevated flag).

Once secureexec is available to setup_new_exec() before the memory
layout, we can add an rlimit sanity-check for setuid execs. (With no
need to clean up since we're past the point of no return.)

Along the way, this fixes comments, renames a variable, and consolidates
dumpability and pdeath_signal clearing, which includes some commit log
archeology to examine the subtle differences between what we had and
what we need.

I'd appreciate some extra eyes on this to make sure this isn't broken
in some special way. Looking at the diffstat, even after all my long
comments, this is a net reduction in lines. :)

Given this crosses a bunch of areas, I think this is likely best to
go via the -mm tree, which is where nearly all of my prior exec work
has lived too.

Thanks!

-Kees
----------------------------------------------------------------
Kees Cook (15):
      binfmt: Introduce secureexec flag
      exec: Rename bprm->cred_prepared to called_set_creds
      apparmor: Refactor to remove bprm_secureexec hook
      selinux: Refactor to remove bprm_secureexec hook
      smack: Refactor to remove bprm_secureexec hook
      commoncap: Refactor to remove bprm_secureexec hook
      commoncap: Move cap_elevated calculation into bprm_set_creds
      LSM: drop bprm_secureexec hook
      exec: Correct comments about "point of no return"
      exec: Use secureexec for setting dumpability
      exec: Use secureexec for clearing pdeath_signal
      smack: Remove redundant pdeath_signal clearing
      exec: Consolidate dumpability logic
      exec: Use sane stack rlimit under secureexec
      exec: Consolidate pdeath_signal clearing

 fs/binfmt_elf.c                    |  2 +-
 fs/binfmt_elf_fdpic.c              |  2 +-
 fs/binfmt_flat.c                   |  2 +-
 fs/exec.c                          | 56 ++++++++++++++++++++++++++++----------
 include/linux/binfmts.h            | 24 ++++++++++++----
 include/linux/lsm_hooks.h          | 14 ++++------
 include/linux/security.h           |  7 -----
 security/apparmor/domain.c         | 24 ++--------------
 security/apparmor/include/domain.h |  1 -
 security/apparmor/include/file.h   |  3 --
 security/apparmor/lsm.c            |  1 -
 security/commoncap.c               | 50 ++++++++--------------------------
 security/security.c                |  5 ----
 security/selinux/hooks.c           | 26 ++++--------------
 security/smack/smack_lsm.c         | 34 ++---------------------
 security/tomoyo/tomoyo.c           |  2 +-
 16 files changed, 91 insertions(+), 162 deletions(-)

v3:
- collapse brpm_secureexec into bprm_set_creds; ebiederm.
- continue to improve various comments

v2:
- fix missed current_security() uses in LSMs.
- research/consolidate dumpability setting logic
- research/consolidate pdeath_signal clearing logic
- split up logical steps a little more for easier review (and bisection)
- fix some old broken comments

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[PATCH v3 00/15] exec: Use sane stack rlimit under secureexec Kees Cook <keescook@chromium.org> - 2017-07-19 00:30 +0200
  [PATCH v3 05/15] smack: Refactor to remove bprm_secureexec hook Kees Cook <keescook@chromium.org> - 2017-07-19 00:30 +0200
    Re: [PATCH v3 05/15] smack: Refactor to remove bprm_secureexec hook Kees Cook <keescook@chromium.org> - 2017-07-26 06:00 +0200
      Re: [PATCH v3 05/15] smack: Refactor to remove bprm_secureexec hook Casey Schaufler <casey@schaufler-ca.com> - 2017-07-26 20:00 +0200
  [PATCH v3 12/15] smack: Remove redundant pdeath_signal clearing Kees Cook <keescook@chromium.org> - 2017-07-19 00:30 +0200
  [PATCH v3 14/15] exec: Use sane stack rlimit under secureexec Kees Cook <keescook@chromium.org> - 2017-07-19 00:30 +0200
    Re: [PATCH v3 14/15] exec: Use sane stack rlimit under secureexec James Morris <jmorris@namei.org> - 2017-07-19 11:50 +0200
  [PATCH v3 11/15] exec: Use secureexec for clearing pdeath_signal Kees Cook <keescook@chromium.org> - 2017-07-19 00:30 +0200
  [PATCH v3 06/15] commoncap: Refactor to remove bprm_secureexec hook Kees Cook <keescook@chromium.org> - 2017-07-19 00:30 +0200
    Re: [PATCH v3 06/15] commoncap: Refactor to remove bprm_secureexec hook Andy Lutomirski <luto@kernel.org> - 2017-07-19 03:20 +0200
      Re: [PATCH v3 06/15] commoncap: Refactor to remove bprm_secureexec hook Kees Cook <keescook@chromium.org> - 2017-07-19 06:50 +0200
      Re: [PATCH v3 06/15] commoncap: Refactor to remove bprm_secureexec hook Andy Lutomirski <luto@kernel.org> - 2017-07-20 07:00 +0200
    Re: [PATCH v3 06/15] commoncap: Refactor to remove bprm_secureexec  hook James Morris <jmorris@namei.org> - 2017-07-19 11:30 +0200
  [PATCH v3 01/15] binfmt: Introduce secureexec flag Kees Cook <keescook@chromium.org> - 2017-07-19 00:30 +0200
    Re: [PATCH v3 01/15] binfmt: Introduce secureexec flag John Johansen <john.johansen@canonical.com> - 2017-07-19 02:10 +0200
    Re: [PATCH v3 01/15] binfmt: Introduce secureexec flag Andy Lutomirski <luto@kernel.org> - 2017-07-19 03:10 +0200
  [PATCH v3 15/15] exec: Consolidate pdeath_signal clearing Kees Cook <keescook@chromium.org> - 2017-07-19 00:30 +0200
  [PATCH v3 13/15] exec: Consolidate dumpability logic Kees Cook <keescook@chromium.org> - 2017-07-19 00:30 +0200
  [PATCH v3 07/15] commoncap: Move cap_elevated calculation into bprm_set_creds Kees Cook <keescook@chromium.org> - 2017-07-19 00:30 +0200
    Re: [PATCH v3 07/15] commoncap: Move cap_elevated calculation into bprm_set_creds Andy Lutomirski <luto@kernel.org> - 2017-07-19 04:00 +0200
    Re: [PATCH v3 07/15] commoncap: Move cap_elevated calculation into  bprm_set_creds James Morris <jmorris@namei.org> - 2017-07-19 11:30 +0200
  [PATCH v3 10/15] exec: Use secureexec for setting dumpability Kees Cook <keescook@chromium.org> - 2017-07-19 00:30 +0200
    Re: [PATCH v3 10/15] exec: Use secureexec for setting dumpability Kees Cook <keescook@chromium.org> - 2017-07-26 06:00 +0200
  [PATCH v3 04/15] selinux: Refactor to remove bprm_secureexec hook Kees Cook <keescook@chromium.org> - 2017-07-19 00:40 +0200
    Re: [PATCH v3 04/15] selinux: Refactor to remove bprm_secureexec hook Paul Moore <paul@paul-moore.com> - 2017-07-20 02:10 +0200
      Re: [PATCH v3 04/15] selinux: Refactor to remove bprm_secureexec hook Paul Moore <paul@paul-moore.com> - 2017-07-20 02:20 +0200
        Re: [PATCH v3 04/15] selinux: Refactor to remove bprm_secureexec hook Kees Cook <keescook@chromium.org> - 2017-07-20 03:40 +0200
          Re: [PATCH v3 04/15] selinux: Refactor to remove bprm_secureexec hook Paul Moore <paul@paul-moore.com> - 2017-07-20 15:50 +0200
            Re: [PATCH v3 04/15] selinux: Refactor to remove bprm_secureexec hook Kees Cook <keescook@chromium.org> - 2017-07-20 19:10 +0200
              Re: [PATCH v3 04/15] selinux: Refactor to remove bprm_secureexec hook Paul Moore <paul@paul-moore.com> - 2017-07-20 22:50 +0200
                Re: [PATCH v3 04/15] selinux: Refactor to remove bprm_secureexec hook Paul Moore <paul@paul-moore.com> - 2017-07-21 17:50 +0200
                Re: [PATCH v3 04/15] selinux: Refactor to remove bprm_secureexec hook Kees Cook <keescook@chromium.org> - 2017-07-21 19:40 +0200
                Re: [PATCH v3 04/15] selinux: Refactor to remove bprm_secureexec hook Paul Moore <paul@paul-moore.com> - 2017-07-21 21:20 +0200
  [PATCH v3 02/15] exec: Rename bprm->cred_prepared to called_set_creds Kees Cook <keescook@chromium.org> - 2017-07-19 00:40 +0200
    Re: [PATCH v3 02/15] exec: Rename bprm->cred_prepared to  called_set_creds John Johansen <john.johansen@canonical.com> - 2017-07-19 02:10 +0200
    Re: [PATCH v3 02/15] exec: Rename bprm->cred_prepared to called_set_creds Andy Lutomirski <luto@kernel.org> - 2017-07-19 03:10 +0200
      Re: [PATCH v3 02/15] exec: Rename bprm->cred_prepared to called_set_creds Kees Cook <keescook@chromium.org> - 2017-07-19 06:50 +0200
    Re: [PATCH v3 02/15] exec: Rename bprm->cred_prepared to  called_set_creds James Morris <jmorris@namei.org> - 2017-07-19 11:30 +0200
    Re: [PATCH v3 02/15] exec: Rename bprm->cred_prepared to called_set_creds Paul Moore <paul@paul-moore.com> - 2017-07-20 02:00 +0200
  Re: [PATCH v3 00/15] exec: Use sane stack rlimit under secureexec Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-19 01:10 +0200
  Re: [PATCH v3 00/15] exec: Use sane stack rlimit under secureexec "Serge E. Hallyn" <serge@hallyn.com> - 2017-07-19 05:30 +0200
    Re: [PATCH v3 00/15] exec: Use sane stack rlimit under secureexec Kees Cook <keescook@chromium.org> - 2017-07-19 07:30 +0200

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