On Tue, Jul 18, 2017 at 6:25 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> 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: Paul Moore <paul@xxxxxxxxxxxxxx>
> Cc: Stephen Smalley <sds@xxxxxxxxxxxxx>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
> security/selinux/hooks.c | 24 +++++-------------------
> 1 file changed, 5 insertions(+), 19 deletions(-)
This seems reasonable in the context of the other changes.
Stephen just posted an AT_SECURE test for the selinux-testsuite on the
SELinux mailing list, it would be nice to ensure that this patchset
doesn't run afoul of that.
Acked-by: Paul Moore <paul@xxxxxxxxxxxxxx>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 0f1450a06b02..18038f73a2f7 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -2413,30 +2413,17 @@ 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)
> @@ -6151,7 +6138,6 @@ 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
--
paul moore
www.paul-moore.com
