From: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
When the bpf_skb_adjust_room() shrinks the skb such that
its csum_start is invalid, the skb->ip_summed should
be reset from CHECKSUM_PARTIAL to CHECKSUM_NONE.
This patch adds a test to ensure the skb->ip_summed changed
from CHECKSUM_PARTIAL to CHECKSUM_NONE after bpf_skb_adjust_room().
Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
---
.../selftests/bpf/prog_tests/decap_sanity.c | 83 +++++++++++++++++++
.../selftests/bpf/progs/bpf_tracing_net.h | 6 ++
.../selftests/bpf/progs/decap_sanity.c | 68 +++++++++++++++
3 files changed, 157 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/decap_sanity.c
create mode 100644 tools/testing/selftests/bpf/progs/decap_sanity.c
diff --git a/tools/testing/selftests/bpf/prog_tests/decap_sanity.c b/tools/testing/selftests/bpf/prog_tests/decap_sanity.c
new file mode 100644
index 000000000000..2fbb3017b740
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/decap_sanity.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <net/if.h>
+#include <linux/in6.h>
+
+#include "test_progs.h"
+#include "network_helpers.h"
+#include "decap_sanity.skel.h"
+
+#define SYS(fmt, ...) \
+ ({ \
+ char cmd[1024]; \
+ snprintf(cmd, sizeof(cmd), fmt, ##__VA_ARGS__); \
+ if (!ASSERT_OK(system(cmd), cmd)) \
+ goto fail; \
+ })
+
+#define NS_TEST "decap_sanity_ns"
+#define IPV6_IFACE_ADDR "face::1"
+#define UDP_TEST_PORT 7777
+
+void test_decap_sanity(void)
+{
+ LIBBPF_OPTS(bpf_tc_hook, qdisc_hook, .attach_point = BPF_TC_EGRESS);
+ LIBBPF_OPTS(bpf_tc_opts, tc_attach);
+ struct nstoken *nstoken = NULL;
+ struct decap_sanity *skel;
+ struct sockaddr_in6 addr;
+ socklen_t addrlen;
+ char buf[128] = {};
+ int sockfd, err;
+
+ skel = decap_sanity__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel open_and_load"))
+ return;
+
+ SYS("ip netns add %s", NS_TEST);
+ SYS("ip -net %s -6 addr add %s/128 dev lo nodad", NS_TEST, IPV6_IFACE_ADDR);
+ SYS("ip -net %s link set dev lo up", NS_TEST);
+
+ nstoken = open_netns(NS_TEST);
+ if (!ASSERT_OK_PTR(nstoken, "open_netns"))
+ goto fail;
+
+ qdisc_hook.ifindex = if_nametoindex("lo");
+ if (!ASSERT_GT(qdisc_hook.ifindex, 0, "if_nametoindex lo"))
+ goto fail;
+
+ err = bpf_tc_hook_create(&qdisc_hook);
+ if (!ASSERT_OK(err, "create qdisc hook"))
+ goto fail;
+
+ tc_attach.prog_fd = bpf_program__fd(skel->progs.decap_sanity);
+ err = bpf_tc_attach(&qdisc_hook, &tc_attach);
+ if (!ASSERT_OK(err, "attach filter"))
+ goto fail;
+
+ addrlen = sizeof(addr);
+ err = make_sockaddr(AF_INET6, IPV6_IFACE_ADDR, UDP_TEST_PORT,
+ (void *)&addr, &addrlen);
+ if (!ASSERT_OK(err, "make_sockaddr"))
+ goto fail;
+ sockfd = socket(AF_INET6, SOCK_DGRAM, 0);
+ if (!ASSERT_NEQ(sockfd, -1, "socket"))
+ goto fail;
+ err = sendto(sockfd, buf, sizeof(buf), 0, (void *)&addr, addrlen);
+ close(sockfd);
+ if (!ASSERT_EQ(err, sizeof(buf), "send"))
+ goto fail;
+
+ ASSERT_EQ(skel->bss->init_csum_partial, true, "init_csum_partial");
+ ASSERT_EQ(skel->bss->final_csum_none, true, "final_csum_none");
+ ASSERT_EQ(skel->bss->broken_csum_start, false, "broken_csum_start");
+
+fail:
+ if (nstoken)
+ close_netns(nstoken);
+ system("ip netns del " NS_TEST " >& /dev/null");
+ decap_sanity__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/bpf_tracing_net.h b/tools/testing/selftests/bpf/progs/bpf_tracing_net.h
index b394817126cf..cfed4df490f3 100644
--- a/tools/testing/selftests/bpf/progs/bpf_tracing_net.h
+++ b/tools/testing/selftests/bpf/progs/bpf_tracing_net.h
@@ -50,6 +50,12 @@
#define ICSK_TIME_LOSS_PROBE 5
#define ICSK_TIME_REO_TIMEOUT 6
+#define ETH_HLEN 14
+#define ETH_P_IPV6 0x86DD
+
+#define CHECKSUM_NONE 0
+#define CHECKSUM_PARTIAL 3
+
#define IFNAMSIZ 16
#define RTF_GATEWAY 0x0002
diff --git a/tools/testing/selftests/bpf/progs/decap_sanity.c b/tools/testing/selftests/bpf/progs/decap_sanity.c
new file mode 100644
index 000000000000..b85113554cbf
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/decap_sanity.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+
+#include "vmlinux.h"
+#include "bpf_tracing_net.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+
+#define UDP_TEST_PORT 7777
+
+void *bpf_cast_to_kern_ctx(void *) __ksym;
+bool init_csum_partial = false;
+bool final_csum_none = false;
+bool broken_csum_start = false;
+
+static inline unsigned int skb_headlen(const struct sk_buff *skb)
+{
+ return skb->len - skb->data_len;
+}
+
+static unsigned int skb_headroom(const struct sk_buff *skb)
+{
+ return skb->data - skb->head;
+}
+
+static int skb_checksum_start_offset(const struct sk_buff *skb)
+{
+ return skb->csum_start - skb_headroom(skb);
+}
+
+SEC("tc")
+int decap_sanity(struct __sk_buff *skb)
+{
+ struct sk_buff *kskb;
+ struct ipv6hdr ip6h;
+ struct udphdr udph;
+ int err;
+
+ if (skb->protocol != __bpf_constant_htons(ETH_P_IPV6))
+ return TC_ACT_SHOT;
+
+ if (bpf_skb_load_bytes(skb, ETH_HLEN, &ip6h, sizeof(ip6h)))
+ return TC_ACT_SHOT;
+
+ if (ip6h.nexthdr != IPPROTO_UDP)
+ return TC_ACT_SHOT;
+
+ if (bpf_skb_load_bytes(skb, ETH_HLEN + sizeof(ip6h), &udph, sizeof(udph)))
+ return TC_ACT_SHOT;
+
+ if (udph.dest != __bpf_constant_htons(UDP_TEST_PORT))
+ return TC_ACT_SHOT;
+
+ kskb = bpf_cast_to_kern_ctx(skb);
+ init_csum_partial = (kskb->ip_summed == CHECKSUM_PARTIAL);
+ err = bpf_skb_adjust_room(skb, -(s32)(ETH_HLEN + sizeof(ip6h) + sizeof(udph)),
+ 1, BPF_F_ADJ_ROOM_FIXED_GSO);
+ if (err)
+ return TC_ACT_SHOT;
+ final_csum_none = (kskb->ip_summed == CHECKSUM_NONE);
+ if (kskb->ip_summed == CHECKSUM_PARTIAL &&
+ (unsigned int)skb_checksum_start_offset(kskb) >= skb_headlen(kskb))
+ broken_csum_start = true;
+
+ return TC_ACT_SHOT;
+}
+
+char __license[] SEC("license") = "GPL";
--
2.30.2
