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Groups > linux.kernel > #1700518

[PATCH v4 05/15] selinux: Refactor to remove bprm_secureexec hook

From Kees Cook <keescook@chromium.org>
Newsgroups linux.kernel
Subject [PATCH v4 05/15] selinux: Refactor to remove bprm_secureexec hook
Date 2017-08-01 02:00 +0200
Message-ID <u9sLo-4eo-19@gated-at.bofh.it> (permalink)
References <u9sLn-4eo-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

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The SELinux bprm_secureexec hook can be merged with the bprm_set_creds
hook since it's dealing with the same information, and all of the details
are finalized during the first call to the bprm_set_creds hook via
prepare_binprm() (subsequent calls due to binfmt_script, etc, are ignored
via bprm->called_set_creds).

Here, the test can just happen at the end of the bprm_set_creds hook,
and the bprm_secureexec hook can be dropped.

Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Tested-by: Paul Moore <paul@paul-moore.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
---
 security/selinux/hooks.c | 24 +++++-------------------
 1 file changed, 5 insertions(+), 19 deletions(-)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 5d4051541518..edbc1c76964e 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2414,30 +2414,17 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm)
 
 		/* Clear any possibly unsafe personality bits on exec: */
 		bprm->per_clear |= PER_CLEAR_ON_SETID;
-	}
-
-	return 0;
-}
-
-static int selinux_bprm_secureexec(struct linux_binprm *bprm)
-{
-	const struct task_security_struct *tsec = current_security();
-	u32 sid, osid;
-	int atsecure = 0;
-
-	sid = tsec->sid;
-	osid = tsec->osid;
 
-	if (osid != sid) {
 		/* Enable secure mode for SIDs transitions unless
 		   the noatsecure permission is granted between
 		   the two SIDs, i.e. ahp returns 0. */
-		atsecure = avc_has_perm(osid, sid,
-					SECCLASS_PROCESS,
-					PROCESS__NOATSECURE, NULL);
+		rc = avc_has_perm(old_tsec->sid, new_tsec->sid,
+				  SECCLASS_PROCESS, PROCESS__NOATSECURE,
+				  NULL);
+		bprm->secureexec |= !!rc;
 	}
 
-	return !!atsecure;
+	return 0;
 }
 
 static int match_file(const void *p, struct file *file, unsigned fd)
@@ -6152,7 +6139,6 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(bprm_set_creds, selinux_bprm_set_creds),
 	LSM_HOOK_INIT(bprm_committing_creds, selinux_bprm_committing_creds),
 	LSM_HOOK_INIT(bprm_committed_creds, selinux_bprm_committed_creds),
-	LSM_HOOK_INIT(bprm_secureexec, selinux_bprm_secureexec),
 
 	LSM_HOOK_INIT(sb_alloc_security, selinux_sb_alloc_security),
 	LSM_HOOK_INIT(sb_free_security, selinux_sb_free_security),
-- 
2.7.4

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[PATCH v4 00/15] exec: Use sane stack rlimit under secureexec Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
  [PATCH v4 02/15] exec: Correct comments about "point of no return" Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
  [PATCH v4 10/15] exec: Use secureexec for setting dumpability Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
    Re: [PATCH v4 10/15] exec: Use secureexec for setting dumpability James Morris <jmorris@namei.org> - 2017-08-01 02:50 +0200
  [PATCH v4 08/15] commoncap: Move cap_elevated calculation into bprm_set_creds Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
    Re: [PATCH v4 08/15] commoncap: Move cap_elevated calculation into bprm_set_creds Andy Lutomirski <luto@kernel.org> - 2017-08-01 15:50 +0200
  [PATCH v4 11/15] exec: Use secureexec for clearing pdeath_signal Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
  [PATCH v4 05/15] selinux: Refactor to remove bprm_secureexec hook Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
    Re: [PATCH v4 05/15] selinux: Refactor to remove bprm_secureexec  hook James Morris <jmorris@namei.org> - 2017-08-01 02:50 +0200
    Re: [PATCH v4 05/15] selinux: Refactor to remove bprm_secureexec hook Andy Lutomirski <luto@kernel.org> - 2017-08-01 15:30 +0200
  [PATCH v4 09/15] LSM: drop bprm_secureexec hook Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
  [PATCH v4 01/15] exec: Rename bprm->cred_prepared to called_set_creds Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
  [PATCH v4 03/15] binfmt: Introduce secureexec flag Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
    Re: [PATCH v4 03/15] binfmt: Introduce secureexec flag Kees Cook <keescook@chromium.org> - 2017-08-01 02:30 +0200
    Re: [PATCH v4 03/15] binfmt: Introduce secureexec flag James Morris <jmorris@namei.org> - 2017-08-01 02:50 +0200
  [PATCH v4 06/15] smack: Refactor to remove bprm_secureexec hook Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
    Re: [PATCH v4 06/15] smack: Refactor to remove bprm_secureexec  hook James Morris <jmorris@namei.org> - 2017-08-01 02:50 +0200
    Re: [PATCH v4 06/15] smack: Refactor to remove bprm_secureexec hook Casey Schaufler <casey@schaufler-ca.com> - 2017-08-01 17:30 +0200
  [PATCH v4 07/15] commoncap: Refactor to remove bprm_secureexec hook Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
  [PATCH v4 04/15] apparmor: Refactor to remove bprm_secureexec hook Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
  [PATCH v4 13/15] exec: Consolidate dumpability logic Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
  [PATCH v4 12/15] smack: Remove redundant pdeath_signal clearing Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
    Re: [PATCH v4 12/15] smack: Remove redundant pdeath_signal  clearing James Morris <jmorris@namei.org> - 2017-08-01 03:00 +0200
    Re: [PATCH v4 12/15] smack: Remove redundant pdeath_signal clearing Casey Schaufler <casey@schaufler-ca.com> - 2017-08-01 17:30 +0200
  [PATCH v4 15/15] exec: Consolidate pdeath_signal clearing Kees Cook <keescook@chromium.org> - 2017-08-01 02:00 +0200
  Re: [PATCH v4 00/15] exec: Use sane stack rlimit under secureexec Kees Cook <keescook@chromium.org> - 2017-08-01 02:40 +0200
    Re: [PATCH v4 00/15] exec: Use sane stack rlimit under secureexec James Morris <jmorris@namei.org> - 2017-08-01 03:00 +0200
      Re: [PATCH v4 00/15] exec: Use sane stack rlimit under secureexec Kees Cook <keescook@chromium.org> - 2017-08-01 05:10 +0200
        Re: [PATCH v4 00/15] exec: Use sane stack rlimit under secureexec Linus Torvalds <torvalds@linux-foundation.org> - 2017-08-01 07:20 +0200
          Re: [PATCH v4 00/15] exec: Use sane stack rlimit under secureexec Linus Torvalds <torvalds@linux-foundation.org> - 2017-08-01 07:20 +0200
          Re: [PATCH v4 00/15] exec: Use sane stack rlimit under secureexec Kees Cook <keescook@chromium.org> - 2017-08-01 17:10 +0200
            Re: [PATCH v4 00/15] exec: Use sane stack rlimit under secureexec Linus Torvalds <torvalds@linux-foundation.org> - 2017-08-01 22:20 +0200
              Re: [PATCH v4 00/15] exec: Use sane stack rlimit under secureexec Kees Cook <keescook@chromium.org> - 2017-08-01 23:10 +0200

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