diff options
| -rw-r--r-- | sys/net/pf.c | 80 |
1 files changed, 79 insertions, 1 deletions
diff --git a/sys/net/pf.c b/sys/net/pf.c index d47e8283987..91125fceaf4 100644 --- a/sys/net/pf.c +++ b/sys/net/pf.c @@ -1,4 +1,4 @@ -/* $OpenBSD: pf.c,v 1.508 2005/11/14 09:18:55 pascoe Exp $ */ +/* $OpenBSD: pf.c,v 1.509 2006/01/31 03:40:31 frantzen Exp $ */ /* * Copyright (c) 2001 Daniel Hartmeier @@ -127,6 +127,8 @@ int pf_check_threshold(struct pf_threshold *); void pf_change_ap(struct pf_addr *, u_int16_t *, u_int16_t *, u_int16_t *, struct pf_addr *, u_int16_t, u_int8_t, sa_family_t); +int pf_modulate_sack(struct mbuf *, int, struct pf_pdesc *, + struct tcphdr *, struct pf_state_peer *); #ifdef INET6 void pf_change_a6(struct pf_addr *, u_int16_t *, struct pf_addr *, u_int8_t); @@ -1492,6 +1494,63 @@ pf_change_icmp(struct pf_addr *ia, u_int16_t *ip, struct pf_addr *oa, } } + +/* + * Need to modulate the sequence numbers in the TCP SACK option + */ +int +pf_modulate_sack(struct mbuf *m, int off, struct pf_pdesc *pd, + struct tcphdr *th, struct pf_state_peer *dst) +{ + int hlen = (th->th_off << 2) - sizeof(*th), thoptlen = hlen; + u_int8_t opts[MAX_TCPOPTLEN], *opt = opts; + int copyback = 0, i, olen; + struct sackblk sack; + +#define TCPOLEN_SACKLEN (TCPOLEN_SACK + 2) + if (hlen < TCPOLEN_SACKLEN || + !pf_pull_hdr(m, off + sizeof(*th), opts, hlen, NULL, NULL, pd->af)) + return 0; + + while (hlen >= TCPOLEN_SACKLEN) { + olen = opt[1]; + switch (*opt) { + case TCPOPT_EOL: /* FALLTHROUGH */ + case TCPOPT_NOP: + opt++; + hlen--; + break; + case TCPOPT_SACK: + if (olen > hlen) + olen = hlen; + if (olen >= TCPOLEN_SACKLEN) { + for (i = 2; i + TCPOLEN_SACK <= olen; + i += TCPOLEN_SACK) { + memcpy(&sack, &opt[i], sizeof(sack)); + pf_change_a(&sack.start, &th->th_sum, + htonl(ntohl(sack.start) - + dst->seqdiff), 0); + pf_change_a(&sack.end, &th->th_sum, + htonl(ntohl(sack.end) - + dst->seqdiff), 0); + memcpy(&opt[i], &sack, sizeof(sack)); + } + copyback = 1; + } + /* FALLTHROUGH */ + default: + if (olen < 2) + olen = 2; + hlen -= olen; + opt += olen; + } + } + + if (copyback) + m_copyback(m, off + sizeof(*th), thoptlen, opts); + return (copyback); +} + void pf_send_tcp(const struct pf_rule *r, sa_family_t af, const struct pf_addr *saddr, const struct pf_addr *daddr, @@ -4280,6 +4339,25 @@ pf_test_state_tcp(struct pf_state **state, int direction, struct pfi_kif *kif, ackskew = dst->seqlo - ack; + + /* + * Need to demodulate the sequence numbers in any TCP SACK options + * (Selective ACK). We could optionally validate the SACK values + * against the current ACK window, either forwards or backwards, but + * I'm not confident that SACK has been implemented properly + * everywhere. It wouldn't surprise me if several stacks accidently + * SACK too far backwards of previously ACKed data. There really aren't + * any security implications of bad SACKing unless the target stack + * doesn't validate the option length correctly. Someone trying to + * spoof into a TCP connection won't bother blindly sending SACK + * options anyway. + */ + if (dst->seqdiff && (th->th_off << 2) > sizeof(struct tcphdr)) { + if (pf_modulate_sack(m, off, pd, th, dst)) + copyback = 1; + } + + #define MAXACKWINDOW (0xffff + 1500) /* 1500 is an arbitrary fudge factor */ if (SEQ_GEQ(src->seqhi, end) && /* Last octet inside other's window space */ |