Commit ab238f14 authored by Luiz Otavio O Souza's avatar Luiz Otavio O Souza Committed by Kristof Provost
Browse files

pf: ensure we have the correct source/destination IP address in ICMP errors

When we route-to a packet that later turns out to not fit in the
outbound interface MTU we generate an ICMP error.
However, if we've already changed those (i.e. we've passed through a NAT
rule) we have to undo the transformation first.

Obtained from:	pfSense
MFC after:	3 weeks
Sponsored by:	Rubicon Communications, LLC ("Netgate")
Differential Revision:	https://reviews.freebsd.org/D32571
parent cfd8fda1
......@@ -320,6 +320,8 @@ static u_int pf_purge_expired_states(u_int, int);
static void pf_purge_unlinked_rules(void);
static int pf_mtag_uminit(void *, int, int);
static void pf_mtag_free(struct m_tag *);
static void pf_packet_rework_nat(struct mbuf *, struct pf_pdesc *,
int, struct pf_state_key *);
#ifdef INET
static void pf_route(struct mbuf **, struct pf_krule *, int,
struct ifnet *, struct pf_kstate *,
......@@ -341,6 +343,16 @@ extern struct proc *pf_purge_proc;
VNET_DEFINE(struct pf_limit, pf_limits[PF_LIMIT_MAX]);
#define PACKET_UNDO_NAT(_m, _pd, _off, _s, _dir) \
do { \
struct pf_state_key *nk; \
if ((_dir) == PF_OUT) \
nk = (_s)->key[PF_SK_STACK]; \
else \
nk = (_s)->key[PF_SK_WIRE]; \
pf_packet_rework_nat(_m, _pd, _off, nk); \
} while (0)
#define PACKET_LOOPED(pd) ((pd)->pf_mtag && \
(pd)->pf_mtag->flags & PF_PACKET_LOOPED)
......@@ -446,6 +458,83 @@ pf_addr_cmp(struct pf_addr *a, struct pf_addr *b, sa_family_t af)
return (0);
}
static void
pf_packet_rework_nat(struct mbuf *m, struct pf_pdesc *pd, int off,
struct pf_state_key *nk)
{
switch (pd->proto) {
case IPPROTO_TCP: {
struct tcphdr *th = &pd->hdr.tcp;
if (PF_ANEQ(pd->src, &nk->addr[pd->sidx], pd->af))
pf_change_ap(m, pd->src, &th->th_sport, pd->ip_sum,
&th->th_sum, &nk->addr[pd->sidx],
nk->port[pd->sidx], 0, pd->af);
if (PF_ANEQ(pd->dst, &nk->addr[pd->didx], pd->af))
pf_change_ap(m, pd->dst, &th->th_dport, pd->ip_sum,
&th->th_sum, &nk->addr[pd->didx],
nk->port[pd->didx], 0, pd->af);
m_copyback(m, off, sizeof(*th), (caddr_t)th);
break;
}
case IPPROTO_UDP: {
struct udphdr *uh = &pd->hdr.udp;
if (PF_ANEQ(pd->src, &nk->addr[pd->sidx], pd->af))
pf_change_ap(m, pd->src, &uh->uh_sport, pd->ip_sum,
&uh->uh_sum, &nk->addr[pd->sidx],
nk->port[pd->sidx], 1, pd->af);
if (PF_ANEQ(pd->dst, &nk->addr[pd->didx], pd->af))
pf_change_ap(m, pd->dst, &uh->uh_dport, pd->ip_sum,
&uh->uh_sum, &nk->addr[pd->didx],
nk->port[pd->didx], 1, pd->af);
m_copyback(m, off, sizeof(*uh), (caddr_t)uh);
break;
}
case IPPROTO_ICMP: {
struct icmp *ih = &pd->hdr.icmp;
if (nk->port[pd->sidx] != ih->icmp_id) {
pd->hdr.icmp.icmp_cksum = pf_cksum_fixup(
ih->icmp_cksum, ih->icmp_id,
nk->port[pd->sidx], 0);
ih->icmp_id = nk->port[pd->sidx];
pd->sport = &ih->icmp_id;
m_copyback(m, off, ICMP_MINLEN, (caddr_t)ih);
}
/* FALLTHROUGH */
}
default:
if (PF_ANEQ(pd->src, &nk->addr[pd->sidx], pd->af)) {
switch (pd->af) {
case AF_INET:
pf_change_a(&pd->src->v4.s_addr,
pd->ip_sum, nk->addr[pd->sidx].v4.s_addr,
0);
break;
case AF_INET6:
PF_ACPY(pd->src, &nk->addr[pd->sidx], pd->af);
break;
}
}
if (PF_ANEQ(pd->dst, &nk->addr[pd->didx], pd->af)) {
switch (pd->af) {
case AF_INET:
pf_change_a(&pd->dst->v4.s_addr,
pd->ip_sum, nk->addr[pd->didx].v4.s_addr,
0);
break;
case AF_INET6:
PF_ACPY(pd->dst, &nk->addr[pd->didx], pd->af);
break;
}
}
break;
}
}
static __inline uint32_t
pf_hashkey(struct pf_state_key *sk)
{
......@@ -5937,6 +6026,11 @@ pf_route(struct mbuf **m, struct pf_krule *r, int dir, struct ifnet *oifp,
error = EMSGSIZE;
KMOD_IPSTAT_INC(ips_cantfrag);
if (r->rt != PF_DUPTO) {
if (s && pd->nat_rule != NULL)
PACKET_UNDO_NAT(m0, pd,
(ip->ip_hl << 2) + (ip_off & IP_OFFMASK),
s, dir);
icmp_error(m0, ICMP_UNREACH, ICMP_UNREACH_NEEDFRAG, 0,
ifp->if_mtu);
goto done;
......@@ -6104,9 +6198,14 @@ pf_route6(struct mbuf **m, struct pf_krule *r, int dir, struct ifnet *oifp,
nd6_output_ifp(ifp, ifp, m0, &dst, NULL);
else {
in6_ifstat_inc(ifp, ifs6_in_toobig);
if (r->rt != PF_DUPTO)
if (r->rt != PF_DUPTO) {
if (s && pd->nat_rule != NULL)
PACKET_UNDO_NAT(m0, pd,
((caddr_t)ip6 - m0->m_data) +
sizeof(struct ip6_hdr), s, dir);
icmp6_error(m0, ICMP6_PACKET_TOO_BIG, 0, ifp->if_mtu);
else
} else
goto bad;
}
......
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