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pf: improve SCTP validation
As per RFC5061 "4.2. New Parameter Types" the add/delete IP address
parameters (0xc001, 0xc002) may not be present in an INIT or INIT-ACK
chunk. They are only allowed to be present in an ASCONF chunk.
This also prevents unbounded recursion while parsing an SCTP packet.
Approved by: so
Security: FreeBSD-SA-26:14.pf
Security: CVE-2026-7164
PR: 294799
Reported by: Igor Gabriel Sousa e Souza
MFC after: 3 days
Sponsored by: Orange Business Services
---
sys/netpfil/pf/pf.c | 18 +++++++++++++-----
tests/sys/netpfil/pf/sctp.py | 23 +++++++++++++++++++++++
2 files changed, 36 insertions(+), 5 deletions(-)
diff --git a/sys/netpfil/pf/pf.c b/sys/netpfil/pf/pf.c
index 38e4cf3a6801..3eab758296a9 100644
--- a/sys/netpfil/pf/pf.c
+++ b/sys/netpfil/pf/pf.c
@@ -6597,7 +6597,7 @@ again:
static int
pf_multihome_scan(struct mbuf *m, int start, int len, struct pf_pdesc *pd,
- struct pfi_kkif *kif, int op)
+ struct pfi_kkif *kif, int op, bool asconf)
{
int off = 0;
struct pf_sctp_multihome_job *job;
@@ -6700,13 +6700,16 @@ pf_multihome_scan(struct mbuf *m, int start, int len, struct pf_pdesc *pd,
int ret;
struct sctp_asconf_paramhdr ah;
+ if (asconf)
+ return (PF_DROP);
+
if (!pf_pull_hdr(m, start + off, &ah, sizeof(ah),
NULL, NULL, pd->af))
return (PF_DROP);
ret = pf_multihome_scan(m, start + off + sizeof(ah),
ntohs(ah.ph.param_length) - sizeof(ah), pd, kif,
- SCTP_ADD_IP_ADDRESS);
+ SCTP_ADD_IP_ADDRESS, true);
if (ret != PF_PASS)
return (ret);
break;
@@ -6715,12 +6718,15 @@ pf_multihome_scan(struct mbuf *m, int start, int len, struct pf_pdesc *pd,
int ret;
struct sctp_asconf_paramhdr ah;
+ if (asconf)
+ return (PF_DROP);
+
if (!pf_pull_hdr(m, start + off, &ah, sizeof(ah),
NULL, NULL, pd->af))
return (PF_DROP);
ret = pf_multihome_scan(m, start + off + sizeof(ah),
ntohs(ah.ph.param_length) - sizeof(ah), pd, kif,
- SCTP_DEL_IP_ADDRESS);
+ SCTP_DEL_IP_ADDRESS, true);
if (ret != PF_PASS)
return (ret);
break;
@@ -6742,7 +6748,8 @@ pf_multihome_scan_init(struct mbuf *m, int start, int len, struct pf_pdesc *pd,
start += sizeof(struct sctp_init_chunk);
len -= sizeof(struct sctp_init_chunk);
- return (pf_multihome_scan(m, start, len, pd, kif, SCTP_ADD_IP_ADDRESS));
+ return (pf_multihome_scan(m, start, len, pd, kif, SCTP_ADD_IP_ADDRESS,
+ false));
}
int
@@ -6752,7 +6759,8 @@ pf_multihome_scan_asconf(struct mbuf *m, int start, int len,
start += sizeof(struct sctp_asconf_chunk);
len -= sizeof(struct sctp_asconf_chunk);
- return (pf_multihome_scan(m, start, len, pd, kif, SCTP_ADD_IP_ADDRESS));
+ return (pf_multihome_scan(m, start, len, pd, kif, SCTP_ADD_IP_ADDRESS,
+ false));
}
int
diff --git a/tests/sys/netpfil/pf/sctp.py b/tests/sys/netpfil/pf/sctp.py
index a871994ee118..30794f04fcc2 100644
--- a/tests/sys/netpfil/pf/sctp.py
+++ b/tests/sys/netpfil/pf/sctp.py
@@ -597,6 +597,29 @@ class TestSCTP_SRV(VnetTestTemplate):
assert r.getlayer(sp.SCTPChunkInitAck)
assert r.getlayer(sp.SCTP).tag == 42
+ @pytest.mark.require_user("root")
+ @pytest.mark.require_progs(["scapy"])
+ def test_too_many_add_ip(self):
+ import scapy.all as sp
+ DEPTH=90
+ params=[]
+ for i in range(0, DEPTH):
+ ch = sp.SCTPChunkParamAddIPAddr(len=(DEPTH - i) * 8)
+ params.append(ch)
+ packet = sp.IP(src="192.0.2.1", dst="192.0.2.2") \
+ / sp.SCTP(sport=4321, dport=1234) \
+ / sp.SCTPChunkInit(init_tag=1, n_in_streams=1, n_out_streams=1, a_rwnd=1500,
+ params=params)
+ packet.show()
+ sp.hexdump(packet)
+ print("len %d" % len(packet))
+
+ r = sp.sr1(packet, timeout=3)
+ # We should not get a reply to this
+ if r:
+ r.show()
+ assert not r
+
class TestSCTPv6(VnetTestTemplate):
REQUIRED_MODULES = ["sctp", "pf"]
TOPOLOGY = {
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