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