From 755042dec0fcc733d456adc2a74042c529eff039 Mon Sep 17 00:00:00 2001 From: Klement Sekera Date: Wed, 1 Dec 2021 10:14:38 +0000 Subject: ip: reassembly: drop zero length fragments Zero length fragments are invalid and should be dropped. This patch adds that. Type: improvement Change-Id: Ic6466c39ca8bf376efe06bb3b7f5d7f1ae812866 Signed-off-by: Klement Sekera --- src/vnet/ip/ip6_error.h | 1 + src/vnet/ip/reass/ip6_full_reass.c | 8 ++++++++ src/vnet/ip/reass/ip6_sv_reass.c | 8 ++++++++ test/test_reassembly.py | 18 ++++++++++++++++++ 4 files changed, 35 insertions(+) diff --git a/src/vnet/ip/ip6_error.h b/src/vnet/ip/ip6_error.h index 8546b4af8d3..6e5df0ef6ba 100644 --- a/src/vnet/ip/ip6_error.h +++ b/src/vnet/ip/ip6_error.h @@ -89,6 +89,7 @@ _ (REASS_NO_BUF, "out of buffers (drop)") \ _ (REASS_TIMEOUT, "fragments dropped due to reassembly timeout") \ _ (REASS_INTERNAL_ERROR, "drops due to internal reassembly error") \ + _ (REASS_INVALID_FRAG_LEN, "invalid fragment length") \ _ (REASS_UNSUPP_IP_PROTO, "unsupported ip protocol") // clang-format on diff --git a/src/vnet/ip/reass/ip6_full_reass.c b/src/vnet/ip/reass/ip6_full_reass.c index fc7fa180ab0..c9509e3345e 100644 --- a/src/vnet/ip/reass/ip6_full_reass.c +++ b/src/vnet/ip/reass/ip6_full_reass.c @@ -41,6 +41,7 @@ typedef enum IP6_FULL_REASS_RC_TOO_MANY_FRAGMENTS, IP6_FULL_REASS_RC_NO_BUF, IP6_FULL_REASS_RC_HANDOFF, + IP6_FULL_REASS_RC_INVALID_FRAG_LEN, } ip6_full_reass_rc_t; typedef struct @@ -888,6 +889,10 @@ ip6_full_reass_update (vlib_main_t *vm, vlib_node_runtime_t *node, u32 fragment_length = vlib_buffer_length_in_chain (vm, fb) - (fvnb->ip.reass.ip6_frag_hdr_offset + sizeof (*frag_hdr)); + if (0 == fragment_length) + { + return IP6_FULL_REASS_RC_INVALID_FRAG_LEN; + } u32 fragment_last = fvnb->ip.reass.fragment_last = fragment_first + fragment_length - 1; int more_fragments = ip6_frag_hdr_more (frag_hdr); @@ -1207,6 +1212,9 @@ ip6_full_reassembly_inline (vlib_main_t * vm, case IP6_FULL_REASS_RC_INTERNAL_ERROR: counter = IP6_ERROR_REASS_INTERNAL_ERROR; break; + case IP6_FULL_REASS_RC_INVALID_FRAG_LEN: + counter = IP6_ERROR_REASS_INVALID_FRAG_LEN; + break; } if (~0 != counter) { diff --git a/src/vnet/ip/reass/ip6_sv_reass.c b/src/vnet/ip/reass/ip6_sv_reass.c index 3656c5a8f61..58c7d8d8433 100644 --- a/src/vnet/ip/reass/ip6_sv_reass.c +++ b/src/vnet/ip/reass/ip6_sv_reass.c @@ -41,6 +41,7 @@ typedef enum IP6_SV_REASS_RC_TOO_MANY_FRAGMENTS, IP6_SV_REASS_RC_INTERNAL_ERROR, IP6_SV_REASS_RC_UNSUPP_IP_PROTO, + IP6_SV_REASS_RC_INVALID_FRAG_LEN, } ip6_sv_reass_rc_t; typedef struct @@ -400,6 +401,10 @@ ip6_sv_reass_update (vlib_main_t *vm, vlib_node_runtime_t *node, u32 fragment_length = vlib_buffer_length_in_chain (vm, fb) - (fvnb->ip.reass.ip6_frag_hdr_offset + sizeof (*frag_hdr)); + if (0 == fragment_length) + { + return IP6_SV_REASS_RC_INVALID_FRAG_LEN; + } u32 fragment_last = fvnb->ip.reass.fragment_last = fragment_first + fragment_length - 1; fvnb->ip.reass.range_first = fragment_first; @@ -667,6 +672,9 @@ ip6_sv_reassembly_inline (vlib_main_t * vm, case IP6_SV_REASS_RC_INTERNAL_ERROR: counter = IP6_ERROR_REASS_INTERNAL_ERROR; break; + case IP6_SV_REASS_RC_INVALID_FRAG_LEN: + counter = IP6_ERROR_REASS_INVALID_FRAG_LEN; + break; } if (~0 != counter) { diff --git a/test/test_reassembly.py b/test/test_reassembly.py index bd622a94794..faec5f42c30 100644 --- a/test/test_reassembly.py +++ b/test/test_reassembly.py @@ -1392,6 +1392,15 @@ class TestIPv6Reassembly(VppTestCase): self.assertIn(ICMPv6ParamProblem, icmp) self.assert_equal(icmp[ICMPv6ParamProblem].code, 3, "ICMP code") + def test_truncated_fragment(self): + """ truncated fragment """ + pkt = (Ether(src=self.pg0.local_mac, dst=self.pg0.remote_mac) / + IPv6(src=self.pg0.remote_ip6, dst=self.pg0.local_ip6, + nh=44, plen=2) / + IPv6ExtHdrFragment(nh=6)) + + self.send_and_assert_no_replies(self.pg0, [pkt], self.pg0) + def test_invalid_frag_size(self): """ fragment size not a multiple of 8 """ p = (Ether(dst=self.src_if.local_mac, src=self.src_if.remote_mac) / @@ -1917,6 +1926,15 @@ class TestIPv6SVReassembly(VppTestCase): IPv6ExtHdrFragment(id=1)/ICMPv6EchoRequest()) rx = self.send_and_expect(self.src_if, [pkt], self.dst_if) + def test_truncated_fragment(self): + """ truncated fragment """ + pkt = (Ether(src=self.pg0.local_mac, dst=self.pg0.remote_mac) / + IPv6(src=self.pg0.remote_ip6, dst=self.pg0.local_ip6, + nh=44, plen=2) / + IPv6ExtHdrFragment(nh=6)) + + self.send_and_assert_no_replies(self.pg0, [pkt], self.pg0) + class TestIPv4ReassemblyLocalNode(VppTestCase): """ IPv4 Reassembly for packets coming to ip4-local node """ -- cgit 1.2.3-korg