lsm_audit,selinux: pass IB device name by reference

While trying to address a Coverity warning that the dev_name string
might end up unterminated when strcpy'ing it in
selinux_ib_endport_manage_subnet(), I realized that it is possible (and
simpler) to just pass the dev_name pointer directly, rather than copying
the string to a buffer.

The ibendport variable goes out of scope at the end of the function
anyway, so the lifetime of the dev_name pointer will never be shorter
than that of ibendport, thus we can safely just pass the dev_name
pointer and be done with it.
Signed-off-by: NOndrej Mosnacek <omosnace@redhat.com>
Acked-by: NRichard Guy Briggs <rgb@redhat.com>
Signed-off-by: NPaul Moore <paul@paul-moore.com>

include/linux/lsm_audit.h

@@ -53,7 +53,7 @@ struct lsm_ibpkey_audit {
 };
 
 struct lsm_ibendport_audit {
-	char	dev_name[IB_DEVICE_NAME_MAX];
+	const char *dev_name;
 	u8 port;
 };
 

security/selinux/hooks.c

@@ -6850,7 +6850,7 @@ static int selinux_ib_endport_manage_subnet(void *ib_sec, const char *dev_name,
 		return err;
 
 	ad.type = LSM_AUDIT_DATA_IBENDPORT;
-	strncpy(ibendport.dev_name, dev_name, sizeof(ibendport.dev_name));
+	ibendport.dev_name = dev_name;
 	ibendport.port = port_num;
 	ad.u.ibendport = &ibendport;
 	return avc_has_perm(&selinux_state,