From: Cong Wang <cong.wang@xxxxxxxxxxxxx>
As requested by Daniel, we need to add a selftest to cover
bpf_skb_change_tail() cases in skb_verdict. Here we test trimming,
growing and error cases, and validate its expected return values.
Cc: John Fastabend <john.fastabend@xxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Zijian Zhang <zijianzhang@xxxxxxxxxxxxx>
Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
---
.../selftests/bpf/prog_tests/sockmap_basic.c | 51 +++++++++++++++++++
.../bpf/progs/test_sockmap_change_tail.c | 40 +++++++++++++++
2 files changed, 91 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/test_sockmap_change_tail.c
diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
index 82bfb266741c..fe735fced836 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
@@ -12,6 +12,7 @@
#include "test_sockmap_progs_query.skel.h"
#include "test_sockmap_pass_prog.skel.h"
#include "test_sockmap_drop_prog.skel.h"
+#include "test_sockmap_change_tail.skel.h"
#include "bpf_iter_sockmap.skel.h"
#include "sockmap_helpers.h"
@@ -562,6 +563,54 @@ static void test_sockmap_skb_verdict_fionread(bool pass_prog)
test_sockmap_drop_prog__destroy(drop);
}
+static void test_sockmap_skb_verdict_change_tail(void)
+{
+ struct test_sockmap_change_tail *skel;
+ int err, map, verdict;
+ int c1, p1, sent, recvd;
+ int zero = 0;
+ char b[3];
+
+ skel = test_sockmap_change_tail__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "open_and_load"))
+ return;
+ verdict = bpf_program__fd(skel->progs.prog_skb_verdict);
+ map = bpf_map__fd(skel->maps.sock_map_rx);
+
+ err = bpf_prog_attach(verdict, map, BPF_SK_SKB_STREAM_VERDICT, 0);
+ if (!ASSERT_OK(err, "bpf_prog_attach"))
+ goto out;
+ err = create_pair(AF_INET, SOCK_STREAM, &c1, &p1);
+ if (!ASSERT_OK(err, "create_pair()"))
+ goto out;
+ err = bpf_map_update_elem(map, &zero, &c1, BPF_NOEXIST);
+ if (!ASSERT_OK(err, "bpf_map_update_elem(c1)"))
+ goto out_close;
+ sent = xsend(p1, "Tr", 2, 0);
+ ASSERT_EQ(sent, 2, "xsend(p1)");
+ recvd = recv(c1, b, 2, 0);
+ ASSERT_EQ(recvd, 1, "recv(c1)");
+ ASSERT_EQ(skel->data->change_tail_ret, 0, "change_tail_ret");
+
+ sent = xsend(p1, "G", 1, 0);
+ ASSERT_EQ(sent, 1, "xsend(p1)");
+ recvd = recv(c1, b, 2, 0);
+ ASSERT_EQ(recvd, 2, "recv(c1)");
+ ASSERT_EQ(skel->data->change_tail_ret, 0, "change_tail_ret");
+
+ sent = xsend(p1, "E", 1, 0);
+ ASSERT_EQ(sent, 1, "xsend(p1)");
+ recvd = recv(c1, b, 1, 0);
+ ASSERT_EQ(recvd, 1, "recv(c1)");
+ ASSERT_EQ(skel->data->change_tail_ret, -EINVAL, "change_tail_ret");
+
+out_close:
+ close(c1);
+ close(p1);
+out:
+ test_sockmap_change_tail__destroy(skel);
+}
+
static void test_sockmap_skb_verdict_peek_helper(int map)
{
int err, c1, p1, zero = 0, sent, recvd, avail;
@@ -927,6 +976,8 @@ void test_sockmap_basic(void)
test_sockmap_skb_verdict_fionread(true);
if (test__start_subtest("sockmap skb_verdict fionread on drop"))
test_sockmap_skb_verdict_fionread(false);
+ if (test__start_subtest("sockmap skb_verdict change tail"))
+ test_sockmap_skb_verdict_change_tail();
if (test__start_subtest("sockmap skb_verdict msg_f_peek"))
test_sockmap_skb_verdict_peek();
if (test__start_subtest("sockmap skb_verdict msg_f_peek with link"))
diff --git a/tools/testing/selftests/bpf/progs/test_sockmap_change_tail.c b/tools/testing/selftests/bpf/progs/test_sockmap_change_tail.c
new file mode 100644
index 000000000000..2796dd8545eb
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_sockmap_change_tail.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 ByteDance */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct {
+ __uint(type, BPF_MAP_TYPE_SOCKMAP);
+ __uint(max_entries, 1);
+ __type(key, int);
+ __type(value, int);
+} sock_map_rx SEC(".maps");
+
+long change_tail_ret = 1;
+
+SEC("sk_skb")
+int prog_skb_verdict(struct __sk_buff *skb)
+{
+ char *data, *data_end;
+
+ bpf_skb_pull_data(skb, 1);
+ data = (char *)(unsigned long)skb->data;
+ data_end = (char *)(unsigned long)skb->data_end;
+
+ if (data + 1 > data_end)
+ return SK_PASS;
+
+ if (data[0] == 'T') { /* Trim the packet */
+ change_tail_ret = bpf_skb_change_tail(skb, skb->len - 1, 0);
+ return SK_PASS;
+ } else if (data[0] == 'G') { /* Grow the packet */
+ change_tail_ret = bpf_skb_change_tail(skb, skb->len + 1, 0);
+ return SK_PASS;
+ } else if (data[0] == 'E') { /* Error */
+ change_tail_ret = bpf_skb_change_tail(skb, 65535, 0);
+ return SK_PASS;
+ }
+ return SK_PASS;
+}
+
+char _license[] SEC("license") = "GPL";
