selinux: reject setexeccon() on MNT_NOSUID applications with -EACCES
We presently prevent processes from using setexecon() to set the
security label of exec()'d processes when NO_NEW_PRIVS is enabled by
returning an error; however, we silently ignore setexeccon() when
exec()'ing from a nosuid mounted filesystem. This patch makes things
a bit more consistent by returning an error in the setexeccon()/nosuid
case.
Signed-off-by: Paul Moore <pmoore@redhat.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 889cf4c..b03b077 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2123,11 +2123,13 @@
new_tsec->exec_sid = 0;
/*
- * Minimize confusion: if no_new_privs and a transition is
- * explicitly requested, then fail the exec.
+ * Minimize confusion: if no_new_privs or nosuid and a
+ * transition is explicitly requested, then fail the exec.
*/
if (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)
return -EPERM;
+ if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)
+ return -EACCES;
} else {
/* Check for a default transition on this program. */
rc = security_transition_sid(old_tsec->sid, isec->sid,