netdev - Re: [PATCH net v3 2/2] bpf: selftests: send packet to devmap redirect XDP

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Message-ID: <87seu8dkfs.fsf@toke.dk>
Date: Tue, 10 Sep 2024 09:41:59 +0200
From: Toke Høiland-Jørgensen <toke@...hat.com>
To: Florian Kauer <florian.kauer@...utronix.de>, Alexei Starovoitov
 <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, "David S.
 Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Jesper
 Dangaard Brouer <hawk@...nel.org>, John Fastabend
 <john.fastabend@...il.com>, Andrii Nakryiko <andrii@...nel.org>, Martin
 KaFai Lau <martin.lau@...ux.dev>, Eduard Zingerman <eddyz87@...il.com>,
 Song Liu <song@...nel.org>, Yonghong Song <yonghong.song@...ux.dev>, KP
 Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, Hao Luo
 <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>, David Ahern
 <dsahern@...nel.org>, Hangbin Liu <liuhangbin@...il.com>, Mykola Lysenko
 <mykolal@...com>, Shuah Khan <shuah@...nel.org>
Cc: netdev@...r.kernel.org, bpf@...r.kernel.org,
 linux-kernel@...r.kernel.org, Jesper Dangaard Brouer <brouer@...hat.com>,
 linux-kselftest@...r.kernel.org, Florian Kauer
 <florian.kauer@...utronix.de>
Subject: Re: [PATCH net v3 2/2] bpf: selftests: send packet to devmap
 redirect XDP

Florian Kauer <florian.kauer@...utronix.de> writes:

> The current xdp_devmap_attach test attaches a program
> that redirects to another program via devmap.
>
> It is, however, never executed, so do that to catch
> any bugs that might occur during execution.
>
> Also, execute the same for a veth pair so that we
> also cover the non-generic path.
>
> Warning: Running this without the bugfix in this series
> will likely crash your system.
>
> Signed-off-by: Florian Kauer <florian.kauer@...utronix.de>
> ---
>  .../selftests/bpf/prog_tests/xdp_devmap_attach.c   | 114 +++++++++++++++++++--
>  1 file changed, 108 insertions(+), 6 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c b/tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c
> index ce6812558287..3da45f719736 100644
> --- a/tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c
> +++ b/tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c
> @@ -1,6 +1,9 @@
>  // SPDX-License-Identifier: GPL-2.0
> +#include <arpa/inet.h>
>  #include <uapi/linux/bpf.h>
>  #include <linux/if_link.h>
> +#include <network_helpers.h>
> +#include <net/if.h>
>  #include <test_progs.h>
>  
>  #include "test_xdp_devmap_helpers.skel.h"
> @@ -17,7 +20,7 @@ static void test_xdp_with_devmap_helpers(void)
>  		.ifindex = IFINDEX_LO,
>  	};
>  	__u32 len = sizeof(info);
> -	int err, dm_fd, map_fd;
> +	int err, dm_fd, dm_fd_redir, map_fd;
>  	__u32 idx = 0;
>  
>  
> @@ -25,14 +28,11 @@ static void test_xdp_with_devmap_helpers(void)
>  	if (!ASSERT_OK_PTR(skel, "test_xdp_with_devmap_helpers__open_and_load"))
>  		return;
>  
> -	dm_fd = bpf_program__fd(skel->progs.xdp_redir_prog);
> -	err = bpf_xdp_attach(IFINDEX_LO, dm_fd, XDP_FLAGS_SKB_MODE, NULL);
> +	dm_fd_redir = bpf_program__fd(skel->progs.xdp_redir_prog);
> +	err = bpf_xdp_attach(IFINDEX_LO, dm_fd_redir, XDP_FLAGS_SKB_MODE, NULL);
>  	if (!ASSERT_OK(err, "Generic attach of program with 8-byte devmap"))
>  		goto out_close;
>  
> -	err = bpf_xdp_detach(IFINDEX_LO, XDP_FLAGS_SKB_MODE, NULL);
> -	ASSERT_OK(err, "XDP program detach");
> -
>  	dm_fd = bpf_program__fd(skel->progs.xdp_dummy_dm);
>  	map_fd = bpf_map__fd(skel->maps.dm_ports);
>  	err = bpf_prog_get_info_by_fd(dm_fd, &info, &len);
> @@ -47,6 +47,23 @@ static void test_xdp_with_devmap_helpers(void)
>  	ASSERT_OK(err, "Read devmap entry");
>  	ASSERT_EQ(info.id, val.bpf_prog.id, "Match program id to devmap entry prog_id");
>  
> +	/* send a packet to trigger any potential bugs in there */
> +	char data[10] = {};
> +	DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
> +			    .data_in = &data,
> +			    .data_size_in = 10,
> +			    .flags = BPF_F_TEST_XDP_LIVE_FRAMES,
> +			    .repeat = 1,
> +		);
> +	err = bpf_prog_test_run_opts(dm_fd_redir, &opts);
> +	ASSERT_OK(err, "XDP test run");
> +
> +	/* wait for the packets to be flushed */
> +	kern_sync_rcu();
> +
> +	err = bpf_xdp_detach(IFINDEX_LO, XDP_FLAGS_SKB_MODE, NULL);
> +	ASSERT_OK(err, "XDP program detach");
> +
>  	/* can not attach BPF_XDP_DEVMAP program to a device */
>  	err = bpf_xdp_attach(IFINDEX_LO, dm_fd, XDP_FLAGS_SKB_MODE, NULL);
>  	if (!ASSERT_NEQ(err, 0, "Attach of BPF_XDP_DEVMAP program"))
> @@ -124,6 +141,88 @@ static void test_xdp_with_devmap_frags_helpers(void)
>  	test_xdp_with_devmap_frags_helpers__destroy(skel);
>  }
>  
> +static void test_xdp_with_devmap_helpers_veth(void)
> +{
> +	struct test_xdp_with_devmap_helpers *skel = NULL;
> +	struct bpf_prog_info info = {};
> +	struct bpf_devmap_val val = {};
> +	struct nstoken *nstoken = NULL;
> +	__u32 len = sizeof(info);
> +	int err, dm_fd, dm_fd_redir, map_fd, ifindex_dst;
> +	__u32 idx = 0;
> +
> +	SYS(out_close, "ip netns add testns");
> +	nstoken = open_netns("testns");
> +	if (!ASSERT_OK_PTR(nstoken, "setns"))
> +		goto out_close;
> +
> +	SYS(out_close, "ip link add veth_src type veth peer name veth_dst");
> +	SYS(out_close, "ip link set dev veth_src up");
> +	SYS(out_close, "ip link set dev veth_dst up");
> +
> +	val.ifindex = if_nametoindex("veth_src");
> +	ifindex_dst = if_nametoindex("veth_dst");
> +	if (!ASSERT_NEQ(val.ifindex, 0, "val.ifindex") ||
> +	    !ASSERT_NEQ(ifindex_dst, 0, "ifindex_dst"))
> +		goto out_close;
> +
> +	skel = test_xdp_with_devmap_helpers__open_and_load();
> +	if (!ASSERT_OK_PTR(skel, "test_xdp_with_devmap_helpers__open_and_load"))
> +		return;

This should be 'goto out_close'.

-Toke