diff mbox series

[bpf,2/2] selftests/bpf: Add a BPF selftest for bpf_skb_change_tail()

Message ID 20241107034141.250815-2-xiyou.wangcong@gmail.com (mailing list archive)
State Needs ACK
Delegated to: BPF
Headers show
Series [bpf,1/2] bpf: check negative offsets in __bpf_skb_min_len() | expand

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Commit Message

Cong Wang Nov. 7, 2024, 3:41 a.m. UTC 
From: Cong Wang <cong.wang@bytedance.com>

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@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Zijian Zhang <zijianzhang@bytedance.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
---
 .../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

Comments

Zijian Zhang Nov. 8, 2024, 12:02 a.m. UTC | #1 
On 11/6/24 7:41 PM, Cong Wang wrote:
> From: Cong Wang <cong.wang@bytedance.com>
> 
> 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@gmail.com>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> Cc: Zijian Zhang <zijianzhang@bytedance.com>
> Signed-off-by: Cong Wang <cong.wang@bytedance.com>
> ---
>   .../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";

LGTM!

I think it will be better if the test could also cover the case you
indicated in the first patch, where skb_transport_offset is a negative
value.

Thanks,
Zijian
diff mbox series

Patch

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";