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PPP, IPCP: check that the peer is allowed to use the IP address it wants

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This is done in the pppd upstream and was disabled because we don't have
the allowed addresses list required for the auth_ip_addr function.

This is mostly necessary for PPP in server mode to prevent the peer to
use the IP address it wants instead of the one we want, which is
currently allowed.

Rewrite auth_ip_addr in a simple way where we forbid PPP peer to use
loopback net, a multicast address or a reserved class address. Added
to that we consider that PPP in server mode with peer required to
authenticate must provide the peer IP address, reject any IP address
wanted by peer different than the one we wanted. This is actually
an allowed addresses "list" of one entry that follows what is done
in the unused auth_ip_addr function.
This commit is contained in:
Sylvain Rochet 2016-11-06 17:39:59 +01:00
parent b978d17ca0
commit 1e6c4ac017
1 changed files with 20 additions and 2 deletions
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22
src/netif/ppp/ipcp.c
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@ -1939,11 +1939,29 @@ static void ipcp_up(fsm *f) {
}
#endif /* LWIP_DNS */
/* FIXME: check why it fails, just to know */
#if 0 /* Unused */
/*
* Check that the peer is allowed to use the IP address it wants.
*/
if (ho->hisaddr != 0) {
u32_t addr = lwip_ntohl(ho->hisaddr);
if ((addr >> IP_CLASSA_NSHIFT) == IP_LOOPBACKNET
|| IP_MULTICAST(addr) || IP_BADCLASS(addr)
/*
* For now, consider that PPP in server mode with peer required
* to authenticate must provide the peer IP address, reject any
* IP address wanted by peer different than the one we wanted.
*/
#if PPP_SERVER && PPP_AUTH_SUPPORT
|| (pcb->settings.auth_required && wo->hisaddr != ho->hisaddr)
#endif /* PPP_SERVER && PPP_AUTH_SUPPORT */
) {
ppp_error("Peer is not authorized to use remote address %I", ho->hisaddr);
ipcp_close(pcb, "Unauthorized remote IP address");
return;
}
}
#if 0 /* Unused */
/* Upstream checking code */
if (ho->hisaddr != 0 && !auth_ip_addr(f->unit, ho->hisaddr)) {
ppp_error("Peer is not authorized to use remote address %I", ho->hisaddr);
ipcp_close(f->unit, "Unauthorized remote IP address");