git: 8de7f8ed5eef - main - pf: reduce IPv6 header parsing code duplication
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Date: Thu, 10 Oct 2024 12:37:12 UTC
The branch main has been updated by kp:
URL: https://cgit.FreeBSD.org/src/commit/?id=8de7f8ed5eefe85b4df068c54059656e12539c4b
commit 8de7f8ed5eefe85b4df068c54059656e12539c4b
Author: Kristof Provost <kp@FreeBSD.org>
AuthorDate: 2024-09-21 16:00:13 +0000
Commit: Kristof Provost <kp@FreeBSD.org>
CommitDate: 2024-10-10 12:10:39 +0000
pf: reduce IPv6 header parsing code duplication
There were two loops in pf_setup_pdesc() and pf_normalize_ip6()
walking over the IPv6 header chain. Merge them into one loop,
adjust some length checks and fix IPv6 jumbo option handling. Also
allow strange but legal IPv6 packets with plen=0 passing through
pf. IPv6 jumbo packets still get dropped.
testing dhill@; ok mcbride@ henning@
Obtained from: OpenBSD, bluhm <bluhm@openbsd.org>, d68283bbf0
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D46925
---
sys/net/pfvar.h | 6 +-
sys/netpfil/pf/pf.c | 261 ++++++++++++++++++++++++++++++++++-------------
sys/netpfil/pf/pf_norm.c | 145 ++++++--------------------
3 files changed, 225 insertions(+), 187 deletions(-)
diff --git a/sys/net/pfvar.h b/sys/net/pfvar.h
index b5d56ab45ce7..1e28693b960d 100644
--- a/sys/net/pfvar.h
+++ b/sys/net/pfvar.h
@@ -2361,8 +2361,10 @@ int pf_normalize_ip(struct mbuf **, struct pfi_kkif *, u_short *,
#endif /* INET */
#ifdef INET6
-int pf_normalize_ip6(struct mbuf **, struct pfi_kkif *, u_short *,
- struct pf_pdesc *);
+int pf_walk_header6(struct mbuf *, uint8_t *, int *, int *, uint32_t *,
+ u_short *);
+int pf_normalize_ip6(struct mbuf **, struct pfi_kkif *, int,
+ u_short *, struct pf_pdesc *);
void pf_poolmask(struct pf_addr *, struct pf_addr*,
struct pf_addr *, struct pf_addr *, sa_family_t);
void pf_addr_inc(struct pf_addr *, sa_family_t);
diff --git a/sys/netpfil/pf/pf.c b/sys/netpfil/pf/pf.c
index 7edf65ae4a09..a482e08dd6ac 100644
--- a/sys/netpfil/pf/pf.c
+++ b/sys/netpfil/pf/pf.c
@@ -363,6 +363,8 @@ static u_int16_t pf_calc_mss(struct pf_addr *, sa_family_t,
int, u_int16_t);
static int pf_check_proto_cksum(struct mbuf *, int, int,
u_int8_t, sa_family_t);
+static int pf_walk_option6(struct mbuf *, int, int, uint32_t *,
+ u_short *);
static void pf_print_state_parts(struct pf_kstate *,
struct pf_state_key *, struct pf_state_key *);
static void pf_patch_8(struct mbuf *, u_int16_t *, u_int8_t *, u_int8_t,
@@ -8460,6 +8462,144 @@ pf_dummynet_route(struct pf_pdesc *pd, struct pf_kstate *s,
return (0);
}
+#ifdef INET6
+static int
+pf_walk_option6(struct mbuf *m, int off, int end, uint32_t *jumbolen,
+ u_short *reason)
+{
+ struct ip6_opt opt;
+ struct ip6_opt_jumbo jumbo;
+ struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
+
+ while (off < end) {
+ if (!pf_pull_hdr(m, off, &opt.ip6o_type, sizeof(opt.ip6o_type),
+ NULL, reason, AF_INET6)) {
+ DPFPRINTF(PF_DEBUG_MISC, ("IPv6 short opt type"));
+ return (PF_DROP);
+ }
+ if (opt.ip6o_type == IP6OPT_PAD1) {
+ off++;
+ continue;
+ }
+ if (!pf_pull_hdr(m, off, &opt, sizeof(opt), NULL, reason,
+ AF_INET6)) {
+ DPFPRINTF(PF_DEBUG_MISC, ("IPv6 short opt"));
+ return (PF_DROP);
+ }
+ if (off + sizeof(opt) + opt.ip6o_len > end) {
+ DPFPRINTF(PF_DEBUG_MISC, ("IPv6 long opt"));
+ REASON_SET(reason, PFRES_IPOPTIONS);
+ return (PF_DROP);
+ }
+ switch (opt.ip6o_type) {
+ case IP6OPT_JUMBO:
+ if (*jumbolen != 0) {
+ DPFPRINTF(PF_DEBUG_MISC, ("IPv6 multiple jumbo"));
+ REASON_SET(reason, PFRES_IPOPTIONS);
+ return (PF_DROP);
+ }
+ if (ntohs(h->ip6_plen) != 0) {
+ DPFPRINTF(PF_DEBUG_MISC, ("IPv6 bad jumbo plen"));
+ REASON_SET(reason, PFRES_IPOPTIONS);
+ return (PF_DROP);
+ }
+ if (!pf_pull_hdr(m, off, &jumbo, sizeof(jumbo), NULL,
+ reason, AF_INET6)) {
+ DPFPRINTF(PF_DEBUG_MISC, ("IPv6 short jumbo"));
+ return (PF_DROP);
+ }
+ memcpy(jumbolen, jumbo.ip6oj_jumbo_len,
+ sizeof(*jumbolen));
+ *jumbolen = ntohl(*jumbolen);
+ if (*jumbolen < IPV6_MAXPACKET) {
+ DPFPRINTF(PF_DEBUG_MISC, ("IPv6 short jumbolen"));
+ REASON_SET(reason, PFRES_IPOPTIONS);
+ return (PF_DROP);
+ }
+ break;
+ default:
+ break;
+ }
+ off += sizeof(opt) + opt.ip6o_len;
+ }
+
+ return (PF_PASS);
+}
+
+int
+pf_walk_header6(struct mbuf *m, uint8_t *nxt, int *off, int *extoff,
+ uint32_t *jumbolen, u_short *reason)
+{
+ struct ip6_ext ext;
+ struct ip6_rthdr rthdr;
+ struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
+ int rthdr_cnt = 0;
+
+ *nxt = h->ip6_nxt;
+ *off = sizeof(struct ip6_hdr);
+ *extoff = 0;
+ *jumbolen = 0;
+ for (;;) {
+ switch (*nxt) {
+ case IPPROTO_FRAGMENT:
+ /* jumbo payload packets cannot be fragmented */
+ if (*jumbolen != 0) {
+ DPFPRINTF(PF_DEBUG_MISC, ("IPv6 fragmented jumbo"));
+ REASON_SET(reason, PFRES_FRAG);
+ return (PF_DROP);
+ }
+ return (PF_PASS);
+ case IPPROTO_ROUTING:
+ if (rthdr_cnt++) {
+ DPFPRINTF(PF_DEBUG_MISC, ("IPv6 multiple rthdr"));
+ REASON_SET(reason, PFRES_IPOPTIONS);
+ return (PF_DROP);
+ }
+ if (!pf_pull_hdr(m, *off, &rthdr, sizeof(rthdr), NULL,
+ reason, AF_INET6)) {
+ DPFPRINTF(PF_DEBUG_MISC, ("IPv6 short rthdr"));
+ return (PF_DROP);
+ }
+ if (rthdr.ip6r_type == IPV6_RTHDR_TYPE_0) {
+ DPFPRINTF(PF_DEBUG_MISC, ("IPv6 rthdr0"));
+ REASON_SET(reason, PFRES_IPOPTIONS);
+ return (PF_DROP);
+ }
+ /* FALLTHROUGH */
+ case IPPROTO_AH:
+ case IPPROTO_HOPOPTS:
+ case IPPROTO_DSTOPTS:
+ if (!pf_pull_hdr(m, *off, &ext, sizeof(ext), NULL,
+ reason, AF_INET6)) {
+ DPFPRINTF(PF_DEBUG_MISC, ("IPv6 short exthdr"));
+ return (PF_DROP);
+ }
+ *extoff = *off;
+ if (*nxt == IPPROTO_HOPOPTS) {
+ if (pf_walk_option6(m, *off + sizeof(ext),
+ *off + (ext.ip6e_len + 1) * 8, jumbolen,
+ reason) != PF_PASS)
+ return (PF_DROP);
+ if (ntohs(h->ip6_plen) == 0 && *jumbolen != 0) {
+ DPFPRINTF(PF_DEBUG_MISC,
+ ("IPv6 missing jumbo"));
+ REASON_SET(reason, PFRES_IPOPTIONS);
+ return (PF_DROP);
+ }
+ }
+ if (*nxt == IPPROTO_AH)
+ *off += (ext.ip6e_len + 2) * 4;
+ else
+ *off += (ext.ip6e_len + 1) * 8;
+ *nxt = ext.ip6e_nxt;
+ break;
+ default:
+ return (PF_PASS);
+ }
+ }
+}
+#endif
+
static void
pf_init_pdesc(struct pf_pdesc *pd, struct mbuf *m)
{
@@ -8554,7 +8694,9 @@ pf_setup_pdesc(sa_family_t af, int dir, struct pf_pdesc *pd, struct mbuf **m0,
#ifdef INET6
case AF_INET6: {
struct ip6_hdr *h;
- int terminal = 0;
+ int extoff;
+ uint32_t jumbolen;
+ uint8_t nxt;
if (__predict_false(m->m_len < sizeof(struct ip6_hdr)) &&
(m = *m0 = m_pullup(*m0, sizeof(struct ip6_hdr))) == NULL) {
@@ -8566,12 +8708,11 @@ pf_setup_pdesc(sa_family_t af, int dir, struct pf_pdesc *pd, struct mbuf **m0,
return (-1);
}
- /* We do IP header normalization and packet reassembly here */
- if (pf_normalize_ip6(m0, kif, reason, pd) != PF_PASS) {
+ if (pf_walk_header6(m, &nxt, off, &extoff, &jumbolen, reason)
+ != PF_PASS) {
*action = PF_DROP;
return (-1);
}
- m = *m0;
h = mtod(m, struct ip6_hdr *);
pd->src = (struct pf_addr *)&h->ip6_src;
@@ -8584,76 +8725,51 @@ pf_setup_pdesc(sa_family_t af, int dir, struct pf_pdesc *pd, struct mbuf **m0,
pd->didx = (dir == PF_IN) ? 1 : 0;
pd->tos = IPV6_DSCP(h);
pd->tot_len = ntohs(h->ip6_plen) + sizeof(struct ip6_hdr);
- *off = ((caddr_t)h - m->m_data) + sizeof(struct ip6_hdr);
pd->virtual_proto = pd->proto = h->ip6_nxt;
pd->act.rtableid = -1;
- do {
- switch (pd->proto) {
- case IPPROTO_FRAGMENT:
- pd->virtual_proto = PF_VPROTO_FRAGMENT;
- if (kif == NULL || r == NULL) /* pflog */
- *action = PF_DROP;
- else
- *action = pf_test_rule(r, s, kif, m, *off,
- pd, a, ruleset, inp,
- *hdrlen);
- if (*action == PF_DROP)
- REASON_SET(reason, PFRES_FRAG);
- return (-1);
- case IPPROTO_ROUTING: {
- struct ip6_rthdr rthdr;
+ /* We do IP header normalization and packet reassembly here */
+ if (pf_normalize_ip6(m0, kif, *off, reason, pd) !=
+ PF_PASS) {
+ *action = PF_DROP;
+ return (-1);
+ }
+ m = *m0;
+ if (m == NULL) {
+ /* packet sits in reassembly queue, no error */
+ *action = PF_PASS;
+ return (-1);
+ }
- if (pd->badopts++) {
- DPFPRINTF(PF_DEBUG_MISC,
- ("pf: IPv6 more than one rthdr"));
- *action = PF_DROP;
- REASON_SET(reason, PFRES_IPOPTIONS);
- return (-1);
- }
- if (!pf_pull_hdr(m, *off, &rthdr, sizeof(rthdr),
- NULL, reason, pd->af)) {
- DPFPRINTF(PF_DEBUG_MISC,
- ("pf: IPv6 short rthdr"));
- *action = PF_DROP;
- REASON_SET(reason, PFRES_SHORT);
- return (-1);
- }
- if (rthdr.ip6r_type == IPV6_RTHDR_TYPE_0) {
- DPFPRINTF(PF_DEBUG_MISC,
- ("pf: IPv6 rthdr0"));
- *action = PF_DROP;
- REASON_SET(reason, PFRES_IPOPTIONS);
- return (-1);
- }
- /* FALLTHROUGH */
- }
- case IPPROTO_AH:
- case IPPROTO_HOPOPTS:
- case IPPROTO_DSTOPTS: {
- /* get next header and header length */
- struct ip6_ext opt6;
-
- if (!pf_pull_hdr(m, *off, &opt6, sizeof(opt6),
- NULL, reason, pd->af)) {
- DPFPRINTF(PF_DEBUG_MISC,
- ("pf: IPv6 short opt"));
- *action = PF_DROP;
- return (-1);
- }
- if (pd->proto == IPPROTO_AH)
- *off += (opt6.ip6e_len + 2) * 4;
- else
- *off += (opt6.ip6e_len + 1) * 8;
- pd->virtual_proto = pd->proto = opt6.ip6e_nxt;
- /* goto the next header */
- break;
- }
- default:
- terminal++;
- break;
- }
- } while (!terminal);
+ /*
+ * Reassembly may have changed the next protocol from fragment
+ * to something else, so update.
+ */
+ h = mtod(m, struct ip6_hdr *);
+ pd->virtual_proto = pd->proto = h->ip6_nxt;
+
+ /* recalc offset, refetch header, then update pd */
+ if (pf_walk_header6(m, &nxt, off, &extoff, &jumbolen, reason) !=
+ PF_PASS) {
+ *action = PF_DROP;
+ return (-1);
+ }
+
+ if (pd->proto == IPPROTO_FRAGMENT) {
+ /*
+ * handle fragments that aren't reassembled by
+ * normalization
+ */
+ pd->virtual_proto = PF_VPROTO_FRAGMENT;
+ if (kif == NULL || r == NULL) /* pflog */
+ *action = PF_DROP;
+ else
+ *action = pf_test_rule(r, s, kif, m, *off,
+ pd, a, ruleset, NULL /* XXX TODO */, *hdrlen);
+ if (*action != PF_PASS)
+ REASON_SET(reason, PFRES_FRAG);
+ return (-1);
+ }
break;
}
@@ -9160,8 +9276,12 @@ pf_test(sa_family_t af, int dir, int pflags, struct ifnet *ifp, struct mbuf **m0
}
done:
+ m = *m0;
PF_RULES_RUNLOCK();
+ if (m == NULL)
+ goto eat_pkt;
+
if (action == PF_PASS && pd.badopts &&
!((s && s->state_flags & PFSTATE_ALLOWOPTS) || r->allow_opts)) {
action = PF_DROP;
@@ -9355,6 +9475,7 @@ done:
break;
}
+eat_pkt:
SDT_PROBE4(pf, ip, test, done, action, reason, r, s);
if (s && action != PF_DROP) {
diff --git a/sys/netpfil/pf/pf_norm.c b/sys/netpfil/pf/pf_norm.c
index 18a9cff2a5c2..a159528c1756 100644
--- a/sys/netpfil/pf/pf_norm.c
+++ b/sys/netpfil/pf/pf_norm.c
@@ -1210,25 +1210,25 @@ pf_normalize_ip(struct mbuf **m0, struct pfi_kkif *kif, u_short *reason,
#ifdef INET6
int
pf_normalize_ip6(struct mbuf **m0, struct pfi_kkif *kif,
- u_short *reason, struct pf_pdesc *pd)
+ int off, u_short *reason, struct pf_pdesc *pd)
{
- struct mbuf *m = *m0;
+ struct mbuf *m;
struct pf_krule *r;
- struct ip6_hdr *h = mtod(m, struct ip6_hdr *);
- int extoff;
- int off;
- struct ip6_ext ext;
- struct ip6_opt opt;
struct ip6_frag frag;
- u_int32_t plen;
- int optend;
- int ooff;
- u_int8_t proto;
- int terminal;
+ int extoff;
+ uint32_t jumbolen;
+ uint8_t nxt;
bool scrub_compat;
PF_RULES_RASSERT();
+again:
+ m = *m0;
+
+ if (pf_walk_header6(m, &nxt, &off, &extoff, &jumbolen, reason)
+ != PF_PASS)
+ return (PF_DROP);
+
r = TAILQ_FIRST(pf_main_ruleset.rules[PF_RULESET_SCRUB].active.ptr);
/*
* Check if there are any scrub rules, matching or not.
@@ -1247,16 +1247,14 @@ pf_normalize_ip6(struct mbuf **m0, struct pfi_kkif *kif,
r = r->skip[PF_SKIP_DIR];
else if (r->af && r->af != AF_INET6)
r = r->skip[PF_SKIP_AF];
-#if 0 /* header chain! */
- else if (r->proto && r->proto != h->ip6_nxt)
+ else if (r->proto && r->proto != pd->proto)
r = r->skip[PF_SKIP_PROTO];
-#endif
else if (PF_MISMATCHAW(&r->src.addr,
- (struct pf_addr *)&h->ip6_src, AF_INET6,
+ (struct pf_addr *)&pd->src, AF_INET6,
r->src.neg, kif, M_GETFIB(m)))
r = r->skip[PF_SKIP_SRC_ADDR];
else if (PF_MISMATCHAW(&r->dst.addr,
- (struct pf_addr *)&h->ip6_dst, AF_INET6,
+ (struct pf_addr *)&pd->dst, AF_INET6,
r->dst.neg, NULL, M_GETFIB(m)))
r = r->skip[PF_SKIP_DST_ADDR];
else
@@ -1276,112 +1274,29 @@ pf_normalize_ip6(struct mbuf **m0, struct pfi_kkif *kif,
pf_rule_to_actions(r, &pd->act);
}
- /* Check for illegal packets */
- if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len)
- goto drop;
-
-again:
- h = mtod(m, struct ip6_hdr *);
- plen = ntohs(h->ip6_plen);
- /* jumbo payload option not supported */
- if (plen == 0)
- goto drop;
-
- extoff = 0;
- off = sizeof(struct ip6_hdr);
- proto = h->ip6_nxt;
- terminal = 0;
- do {
- switch (proto) {
- case IPPROTO_FRAGMENT:
- goto fragment;
- break;
- case IPPROTO_AH:
- case IPPROTO_ROUTING:
- case IPPROTO_DSTOPTS:
- if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
- NULL, AF_INET6))
- goto shortpkt;
- extoff = off;
- if (proto == IPPROTO_AH)
- off += (ext.ip6e_len + 2) * 4;
- else
- off += (ext.ip6e_len + 1) * 8;
- proto = ext.ip6e_nxt;
- break;
- case IPPROTO_HOPOPTS:
- if (!pf_pull_hdr(m, off, &ext, sizeof(ext), NULL,
- NULL, AF_INET6))
- goto shortpkt;
- extoff = off;
- optend = off + (ext.ip6e_len + 1) * 8;
- ooff = off + sizeof(ext);
- do {
- if (!pf_pull_hdr(m, ooff, &opt.ip6o_type,
- sizeof(opt.ip6o_type), NULL, NULL,
- AF_INET6))
- goto shortpkt;
- if (opt.ip6o_type == IP6OPT_PAD1) {
- ooff++;
- continue;
- }
- if (!pf_pull_hdr(m, ooff, &opt, sizeof(opt),
- NULL, NULL, AF_INET6))
- goto shortpkt;
- if (ooff + sizeof(opt) + opt.ip6o_len > optend)
- goto drop;
- if (opt.ip6o_type == IP6OPT_JUMBO)
- goto drop;
- ooff += sizeof(opt) + opt.ip6o_len;
- } while (ooff < optend);
-
- off = optend;
- proto = ext.ip6e_nxt;
- break;
- default:
- terminal = 1;
- break;
- }
- } while (!terminal);
-
- if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
- goto shortpkt;
-
- return (PF_PASS);
-
- fragment:
- if (pd->flags & PFDESC_IP_REAS)
+ if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, reason, AF_INET6))
return (PF_DROP);
- if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len)
- goto shortpkt;
-
- if (!pf_pull_hdr(m, off, &frag, sizeof(frag), NULL, NULL, AF_INET6))
- goto shortpkt;
/* Offset now points to data portion. */
off += sizeof(frag);
- /* Returns PF_DROP or *m0 is NULL or completely reassembled mbuf. */
- if (pf_reassemble6(m0, &frag, off, extoff, reason) != PF_PASS)
- return (PF_DROP);
- m = *m0;
- if (m == NULL)
- return (PF_DROP);
+ if (nxt == IPPROTO_FRAGMENT) {
+ if (pd->flags & PFDESC_IP_REAS)
+ return (PF_DROP);
- pd->flags |= PFDESC_IP_REAS;
- goto again;
+ /* Returns PF_DROP or *m0 is NULL or completely reassembled
+ * mbuf. */
+ if (pf_reassemble6(m0, &frag, off, extoff, reason) != PF_PASS)
+ return (PF_DROP);
- shortpkt:
- REASON_SET(reason, PFRES_SHORT);
- if (r != NULL && r->log)
- PFLOG_PACKET(kif, m, PF_DROP, *reason, r, NULL, NULL, pd, 1);
- return (PF_DROP);
+ pd->flags |= PFDESC_IP_REAS;
+ m = *m0;
+ if (m == NULL)
+ return (PF_DROP);
+ goto again;
+ }
- drop:
- REASON_SET(reason, PFRES_NORM);
- if (r != NULL && r->log)
- PFLOG_PACKET(kif, m, PF_DROP, *reason, r, NULL, NULL, pd, 1);
- return (PF_DROP);
+ return (PF_PASS);
}
#endif /* INET6 */