git: e7f9171b6738 - main - pf: Handle m_len < sizeof(struct ether_header) case

The branch main has been updated by kp:

URL: https://cgit.FreeBSD.org/src/commit/?id=e7f9171b6738809ded7250bc5c78368421255b1b

commit e7f9171b6738809ded7250bc5c78368421255b1b
Author:     Igor Ostapenko <pm@igoro.pro>
AuthorDate: 2024-08-21 10:01:34 +0000
Commit:     Kristof Provost <kp@FreeBSD.org>
CommitDate: 2024-08-21 12:10:03 +0000

    pf: Handle m_len < sizeof(struct ether_header) case
    
    Reviewed by:    kp
    Differential Revision:  https://reviews.freebsd.org/D46391
---
 sys/netpfil/pf/pf.c          |  7 +++++
 tests/sys/netpfil/pf/mbuf.sh | 73 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+)

diff --git a/sys/netpfil/pf/pf.c b/sys/netpfil/pf/pf.c
index ad2dc2e707ed..cb69d06b1fe6 100644
--- a/sys/netpfil/pf/pf.c
+++ b/sys/netpfil/pf/pf.c
@@ -4365,6 +4365,13 @@ pf_test_eth_rule(int dir, struct pfi_kkif *kif, struct mbuf **m0)
 	r = TAILQ_FIRST(rules);
 	rm = NULL;
 
+	if (__predict_false(m->m_len < sizeof(struct ether_header)) &&
+	    (m = *m0 = m_pullup(*m0, sizeof(struct ether_header))) == NULL) {
+		DPFPRINTF(PF_DEBUG_URGENT,
+		    ("pf_test_eth_rule: m_len < sizeof(struct ether_header)"
+		     ", pullup failed\n"));
+		return (PF_DROP);
+	}
 	e = mtod(m, struct ether_header *);
 	proto = ntohs(e->ether_type);
 
diff --git a/tests/sys/netpfil/pf/mbuf.sh b/tests/sys/netpfil/pf/mbuf.sh
index 2dffa48ed2f5..a4664718093a 100644
--- a/tests/sys/netpfil/pf/mbuf.sh
+++ b/tests/sys/netpfil/pf/mbuf.sh
@@ -151,8 +151,81 @@ inet6_in_mbuf_len_cleanup()
 	pft_cleanup
 }
 
+atf_test_case "ethernet_in_mbuf_len" "cleanup"
+ethernet_in_mbuf_len_head()
+{
+	atf_set descr 'Test that pf can handle inbound with the first mbuf with m_len < sizeof(struct ether_header)'
+	atf_set require.user root
+}
+ethernet_in_mbuf_len_body()
+{
+	pft_init
+	dummymbuf_init
+
+	epair=$(vnet_mkepair)
+	epair_a_mac=$(ifconfig ${epair}a ether | awk '/ether/ { print $2; }')
+	ifconfig ${epair}a 192.0.2.1/24 up
+
+	# Set up a simple jail with one interface
+	vnet_mkjail alcatraz ${epair}b
+	jexec alcatraz ifconfig ${epair}b 192.0.2.2/24 up
+	epair_b_mac=$(jexec alcatraz ifconfig ${epair}b ether | awk '/ether/ { print $2; }')
+
+	# Sanity check
+	atf_check -s exit:0 -o ignore ping -c1 192.0.2.2
+
+	# Should be denied
+	jexec alcatraz pfctl -e
+	pft_set_rules alcatraz \
+		"ether block" \
+		"pass"
+	atf_check -s not-exit:0 -o ignore ping -c1 -t1 192.0.2.2
+
+	# Should be allowed by from/to addresses
+	echo $epair_a_mac
+	echo $epair_b_mac
+	pft_set_rules alcatraz \
+		"ether block" \
+		"ether pass in  from ${epair_a_mac} to ${epair_b_mac}" \
+		"ether pass out from ${epair_b_mac} to ${epair_a_mac}" \
+		"pass"
+	atf_check -s exit:0 -o ignore ping -c1 192.0.2.2
+
+	# Should still work for m_len=0
+	jexec alcatraz pfilctl link -i dummymbuf:ethernet ethernet
+	jexec alcatraz sysctl net.dummymbuf.rules="ethernet in ${epair}b pull-head 0;"
+	atf_check_equal "0" "$(jexec alcatraz sysctl -n net.dummymbuf.hits)"
+	atf_check -s exit:0 -o ignore ping -c1 192.0.2.2
+	atf_check_equal "1" "$(jexec alcatraz sysctl -n net.dummymbuf.hits)"
+
+	# m_len=1
+	jexec alcatraz sysctl net.dummymbuf.rules="ethernet in ${epair}b pull-head 1;"
+	jexec alcatraz sysctl net.dummymbuf.hits=0
+	atf_check -s exit:0 -o ignore ping -c1 192.0.2.2
+	atf_check_equal "1" "$(jexec alcatraz sysctl -n net.dummymbuf.hits)"
+
+	# m_len=11
+	# for the simplest L2 Ethernet frame it should impact src field
+	jexec alcatraz sysctl net.dummymbuf.rules="ethernet in ${epair}b pull-head 11;"
+	jexec alcatraz sysctl net.dummymbuf.hits=0
+	atf_check -s exit:0 -o ignore ping -c1 192.0.2.2
+	atf_check_equal "1" "$(jexec alcatraz sysctl -n net.dummymbuf.hits)"
+
+	# m_len=13
+	# provided L2 Ethernet simplest header is 14 bytes long, it should impact ethertype field
+	jexec alcatraz sysctl net.dummymbuf.rules="ethernet in ${epair}b pull-head 13;"
+	jexec alcatraz sysctl net.dummymbuf.hits=0
+	atf_check -s exit:0 -o ignore ping -c1 192.0.2.2
+	atf_check_equal "1" "$(jexec alcatraz sysctl -n net.dummymbuf.hits)"
+}
+ethernet_in_mbuf_len_cleanup()
+{
+	pft_cleanup
+}
+
 atf_init_test_cases()
 {
 	atf_add_test_case "inet_in_mbuf_len"
 	atf_add_test_case "inet6_in_mbuf_len"
+	atf_add_test_case "ethernet_in_mbuf_len"
 }