Following the recent security advisory, add a comment describing our

invariants and approach for protocol switch methods in protsw_init(),
and also some KASSERT's for non-domain init entries in protocol
switch tables: pru_abort and pru_send must both be implemented.

For now, leave those assertions #if 0'd, since there are a few
protocols that violate them in non-harmful ways.  Whether or not we
should enforce pru_abort being implemented for non-stream protocols
is an interesting question: currently abort is only invoked on stream
sockets in situations where un-accepted sockets must be abruptly
closed (i.e., close() on a listen socket with pending connections),
but in principle it is useful for datagram sockets and most datagram
socket types implement it.

MFC after:	3 weeks
This commit is contained in:
Robert Watson 2008-12-25 11:32:38 +00:00
parent 55d25fa424
commit 9c232f86ca

View File

@ -110,6 +110,28 @@ protosw_init(struct protosw *pr)
pr->pr_domain->dom_name,
(int)(pr - pr->pr_domain->dom_protosw)));
/*
* Protocol switch methods fall into three categories: mandatory,
* mandatory but protosw_init() provides a default, and optional.
*
* For true protocols (i.e., pru_attach != NULL), KASSERT truly
* mandatory methods with no defaults, and initialize defaults for
* other mandatory methods if the protocol hasn't defined an
* implementation (NULL function pointer).
*/
#if 0
if (pu->pru_attach != NULL) {
KASSERT(pu->pru_abort != NULL,
("protosw_init: %ssw[%d] pru_abort NULL",
pr->pr_domain->dom_name,
(int)(pr - pr->pr_domain->dom_protosw)));
KASSERT(pu->pru_send != NULL,
("protosw_init: %ssw[%d] pru_send NULL",
pr->pr_domain->dom_name,
(int)(pr - pr->pr_domain->dom_protosw)));
}
#endif
#define DEFAULT(foo, bar) if ((foo) == NULL) (foo) = (bar)
DEFAULT(pu->pru_accept, pru_accept_notsupp);
DEFAULT(pu->pru_bind, pru_bind_notsupp);