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pf: Ensure that IP addresses match in ICMP error packets

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States in pf(4) let ICMP and ICMP6 packets pass if they have a
packet in their payload that matches an exiting connection.  It was
not checked whether the outer ICMP packet has the same destination
IP as the source IP of the inner protocol packet.  Enforce that
these addresses match, to prevent ICMP packets that do not make
sense.

Reported by:	Nicolas Collignon, Corentin Bayet, Eloi Vanderbeken, Luca Moro at Synacktiv
Obtained from:	OpenBSD
Security:	CVE-2019-5598
This commit is contained in:
Kristof Provost 2019-03-21 08:09:52 +00:00
parent e77a99c1c1
commit 64af73aade
1 changed files with 22 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
sys/netpfil/pf/pf.c
View File

@ -4594,7 +4594,7 @@ pf_test_state_icmp(struct pf_state **state, int direction, struct pfi_kif *kif,
{
struct pf_addr *saddr = pd->src, *daddr = pd->dst;
u_int16_t icmpid = 0, *icmpsum;
u_int8_t icmptype;
u_int8_t icmptype, icmpcode;
int state_icmp = 0;
struct pf_state_key_cmp key;
@ -4603,6 +4603,7 @@ pf_test_state_icmp(struct pf_state **state, int direction, struct pfi_kif *kif,
#ifdef INET
case IPPROTO_ICMP:
icmptype = pd->hdr.icmp->icmp_type;
icmpcode = pd->hdr.icmp->icmp_code;
icmpid = pd->hdr.icmp->icmp_id;
icmpsum = &pd->hdr.icmp->icmp_cksum;
@ -4617,6 +4618,7 @@ pf_test_state_icmp(struct pf_state **state, int direction, struct pfi_kif *kif,
#ifdef INET6
case IPPROTO_ICMPV6:
icmptype = pd->hdr.icmp6->icmp6_type;
icmpcode = pd->hdr.icmp6->icmp6_code;
icmpid = pd->hdr.icmp6->icmp6_id;
icmpsum = &pd->hdr.icmp6->icmp6_cksum;
@ -4815,6 +4817,23 @@ pf_test_state_icmp(struct pf_state **state, int direction, struct pfi_kif *kif,
#endif /* INET6 */
}
if (PF_ANEQ(pd->dst, pd2.src, pd->af)) {
if (V_pf_status.debug >= PF_DEBUG_MISC) {
printf("pf: BAD ICMP %d:%d outer dst: ",
icmptype, icmpcode);
pf_print_host(pd->src, 0, pd->af);
printf(" -> ");
pf_print_host(pd->dst, 0, pd->af);
printf(" inner src: ");
pf_print_host(pd2.src, 0, pd2.af);
printf(" -> ");
pf_print_host(pd2.dst, 0, pd2.af);
printf("\n");
}
REASON_SET(reason, PFRES_BADSTATE);
return (PF_DROP);
}
switch (pd2.proto) {
case IPPROTO_TCP: {
struct tcphdr th;
@ -4871,7 +4890,7 @@ pf_test_state_icmp(struct pf_state **state, int direction, struct pfi_kif *kif,
!SEQ_GEQ(seq, src->seqlo - (dst->max_win << dws)))) {
if (V_pf_status.debug >= PF_DEBUG_MISC) {
printf("pf: BAD ICMP %d:%d ",
icmptype, pd->hdr.icmp->icmp_code);
icmptype, icmpcode);
pf_print_host(pd->src, 0, pd->af);
printf(" -> ");
pf_print_host(pd->dst, 0, pd->af);
@ -4884,7 +4903,7 @@ pf_test_state_icmp(struct pf_state **state, int direction, struct pfi_kif *kif,
} else {
if (V_pf_status.debug >= PF_DEBUG_MISC) {
printf("pf: OK ICMP %d:%d ",
icmptype, pd->hdr.icmp->icmp_code);
icmptype, icmpcode);
pf_print_host(pd->src, 0, pd->af);
printf(" -> ");
pf_print_host(pd->dst, 0, pd->af);