linux-kernel - [PATCH GHAK16 V5 00/10] capabilities: do not audit log BPRM

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Date:   Wed, 11 Oct 2017 20:57:04 -0400
From:   Richard Guy Briggs <rgb@...hat.com>
To:     linux-security-module@...r.kernel.org, linux-audit@...hat.com,
        linux-kernel@...r.kernel.org
Cc:     Richard Guy Briggs <rgb@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Andy Lutomirski <luto@...nel.org>,
        "Serge E . Hallyn" <serge.hallyn@...ntu.com>,
        James Morris <james.l.morris@...cle.com>,
        Paul Moore <pmoore@...hat.com>,
        Steve Grubb <sgrubb@...hat.com>, Eric Paris <eparis@...hat.com>
Subject: [PATCH GHAK16 V5 00/10] capabilities: do not audit log BPRM_FCAPS on set*id

The audit subsystem is adding a BPRM_FCAPS record when auditing setuid
application execution (SYSCALL execve). This is not expected as it was
supposed to be limited to when the file system actually had capabilities
in an extended attribute.  It lists all capabilities making the event
really ugly to parse what is happening.  The PATH record correctly
records the setuid bit and owner.  Suppress the BPRM_FCAPS record on
set*id.

See: https://github.com/linux-audit/audit-kernel/issues/16

The first to eighth patches just massage the logic to make it easier to
understand.  Some of them could be squashed together.

The patch that resolves this issue is the ninth.  

It would be possible to address the original issue with a change of
	"!uid_eq(new->euid, root_uid) || !uid_eq(new->uid, root_uid)"
to
	"!(uid_eq(new->euid, root_uid) || uid_eq(new->uid, root_uid))"
but it took me long enough to understand this logic that I don't think
I'd be doing any favours by leaving it this difficult to understand.

The final patch attempts to address all the conditions that need logging
based on mailing list conversations, recoginizing there is probably some
duplication in the logic.

Passes: (ltp 20170516)
	./runltp -f syscalls -s cap
	./runltp -f securebits
	./runltp -f cap_bounds
	./runltp -f filecaps
	make TARGETS=capabilities kselftest (when run locally, fails over nfs)

Since this is mostly capabilities related rather than audit, could this go
through the capabilites (Serge) or security (James) trees please?  Thanks!

v5
  rebase on linux-security/next 4.14-rc2
  added comment block header to handle_privileged_root()
  moved comment in handle_privileged_root()
  moved root_privileged() check back into handle_privileged_root()

v4
  rebase on kees' 4.13 commoncap changes
  minor local func renames

v3
  refactor into several sub-functions
  convert most macros to inline funcs

v2
  use macros to clarify intent of calculations
  fix original logic error
  address additional audit logging conditions

Richard Guy Briggs (10):
  capabilities: factor out cap_bprm_set_creds privileged root
  capabilities: intuitive names for cap gain status
  capabilities: rename has_cap to has_fcap
  capabilities: use root_priveleged inline to clarify logic
  capabilities: use intuitive names for id changes
  capabilities: move audit log decision to function
  capabilities: remove a layer of conditional logic
  capabilities: invert logic for clarity
  capabilities: fix logic for effective root or real root
  capabilities: audit log other surprising conditions

 security/commoncap.c | 193 ++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 128 insertions(+), 65 deletions(-)

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1.8.3.1