Re: [PATCH bpf-next v3 2/3] selftests/bpf: make xdp_cpumap_attach keep redirect prog attached

On 10/9/24 3:12 AM, Alexis Lothoré (eBPF Foundation) wrote:

Current test only checks attach/detach on cpu map type program, and so does not check that it can be properly executed, neither that it redirects correctly.

Update the existing test to extend its coverage:

• keep the redirected program loaded
• try to execute it through bpf_prog_test_run_opts with some dummy context

While at it, bring the following minor improvements:

• isolate test interface in its own namespace
• replicate the test on a veth pair

Signed-off-by: Alexis Lothoré (eBPF Foundation) alexis.lothore@bootlin.com

This change is based on the similar update brought to xdp_devmap_attach ([1]) and then realigns xdp_cpumap_attach with it

[1] https://lore.kernel.org/bpf/20240911-devel-koalo-fix-ingress-ifindex-v4-2-5c...

Changes in v3:

• new patch

---

.../selftests/bpf/prog_tests/xdp_cpumap_attach.c | 124 +++++++++++++++++++-- 1 file changed, 117 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_cpumap_attach.c b/tools/testing/selftests/bpf/prog_tests/xdp_cpumap_attach.c index 481626a875d1c3db9c7bfe92c3cca6e967a6d45c..31c225f0239613f6b5adad36b5b0e6e85eeddd9a 100644 --- a/tools/testing/selftests/bpf/prog_tests/xdp_cpumap_attach.c +++ b/tools/testing/selftests/bpf/prog_tests/xdp_cpumap_attach.c @@ -2,35 +2,41 @@ #include <uapi/linux/bpf.h> #include <linux/if_link.h> #include <test_progs.h> +#include <network_helpers.h> #include "test_xdp_with_cpumap_frags_helpers.skel.h" #include "test_xdp_with_cpumap_helpers.skel.h" #define IFINDEX_LO 1 +#define TEST_NS "cpu_attach_ns" static void test_xdp_with_cpumap_helpers(void) {

• struct test_xdp_with_cpumap_helpers *skel;

• struct test_xdp_with_cpumap_helpers *skel = NULL; struct bpf_prog_info info = {}; __u32 len = sizeof(info); struct bpf_cpumap_val val = { .qsize = 192, };

• int err, prog_fd, map_fd;

• int err, prog_fd, prog_redir_fd, map_fd;
• struct nstoken *nstoken = NULL; __u32 idx = 0;

• SYS(out_close, "ip netns add %s", TEST_NS);
• nstoken = open_netns(TEST_NS);
• if (!ASSERT_OK_PTR(nstoken, "open_netns"))

• goto out_close;
  

• SYS(out_close, "ip link set dev lo up");

There is easier helper netns_{new,free} to do all these: netns_obj = netns_new(TEST_NS, true);

Only fyi for your future work.

• skel = test_xdp_with_cpumap_helpers__open_and_load(); if (!ASSERT_OK_PTR(skel, "test_xdp_with_cpumap_helpers__open_and_load")) return;

• prog_fd = bpf_program__fd(skel->progs.xdp_redir_prog);
• err = bpf_xdp_attach(IFINDEX_LO, prog_fd, XDP_FLAGS_SKB_MODE, NULL);

• prog_redir_fd = bpf_program__fd(skel->progs.xdp_redir_prog);
• err = bpf_xdp_attach(IFINDEX_LO, prog_redir_fd, XDP_FLAGS_SKB_MODE, NULL); if (!ASSERT_OK(err, "Generic attach of program with 8-byte CPUMAP")) goto out_close;

• err = bpf_xdp_detach(IFINDEX_LO, XDP_FLAGS_SKB_MODE, NULL);
• ASSERT_OK(err, "XDP program detach");
• prog_fd = bpf_program__fd(skel->progs.xdp_dummy_cm); map_fd = bpf_map__fd(skel->maps.cpu_map); err = bpf_prog_get_info_by_fd(prog_fd, &info, &len);

@@ -45,6 +51,23 @@ static void test_xdp_with_cpumap_helpers(void) ASSERT_OK(err, "Read cpumap entry"); ASSERT_EQ(info.id, val.bpf_prog.id, "Match program id to cpumap 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(prog_redir_fd, &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_CPUMAP program to a device */ err = bpf_xdp_attach(IFINDEX_LO, prog_fd, XDP_FLAGS_SKB_MODE, NULL); if (!ASSERT_NEQ(err, 0, "Attach of BPF_XDP_CPUMAP program"))

@@ -65,6 +88,8 @@ static void test_xdp_with_cpumap_helpers(void) ASSERT_NEQ(err, 0, "Add BPF_XDP program with frags to cpumap entry"); out_close:

• close_netns(nstoken);
• SYS_NOFAIL("ip netns del %s", TEST_NS); test_xdp_with_cpumap_helpers__destroy(skel); }

@@ -111,6 +136,88 @@ static void test_xdp_with_cpumap_frags_helpers(void) test_xdp_with_cpumap_frags_helpers__destroy(skel); } +static void test_xdp_with_cpumap_helpers_veth(void)

Unlike the devmap redirect, cpumap redirects pkt to another cpu instead of another veth dev. veth test is not very useful here for cpumap, so I take the veth test out.

+{

• int err, cm_fd, cm_fd_redir, map_fd, ifindex_dst, ifindex_src;
• struct test_xdp_with_cpumap_helpers *skel = NULL;
• struct bpf_prog_info info = {};
• struct bpf_cpumap_val val = {

• .qsize = 192
  

• };
• struct nstoken *nstoken = NULL;
• __u32 len = sizeof(info);
• __u32 idx = 0;
• SYS(out_close, "ip netns add %s", TEST_NS);
• nstoken = open_netns(TEST_NS);
• if (!ASSERT_OK_PTR(nstoken, "open_netns"))

• 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");
• ifindex_src = if_nametoindex("veth_src");
• ifindex_dst = if_nametoindex("veth_dst");
• if (!ASSERT_NEQ(ifindex_src, 0, "val.ifindex") ||

•    !ASSERT_NEQ(ifindex_dst, 0, "ifindex_dst"))
  

• goto out_close;
  

• skel = test_xdp_with_cpumap_helpers__open_and_load();
• if (!ASSERT_OK_PTR(skel, "test_xdp_with_cpumap_helpers__open_and_load"))

• goto out_close;
  

• cm_fd_redir = bpf_program__fd(skel->progs.xdp_redir_prog);
• err = bpf_xdp_attach(ifindex_src, cm_fd_redir, XDP_FLAGS_DRV_MODE, NULL);
• if (!ASSERT_OK(err, "Attach of program with 8-byte cpumap"))

• goto out_close;
  

• cm_fd = bpf_program__fd(skel->progs.xdp_dummy_cm);
• map_fd = bpf_map__fd(skel->maps.cpu_map);
• err = bpf_prog_get_info_by_fd(cm_fd, &info, &len);
• if (!ASSERT_OK(err, "bpf_prog_get_info_by_fd"))

• goto out_close;
  

• val.bpf_prog.fd = cm_fd;
• err = bpf_map_update_elem(map_fd, &idx, &val, 0);
• ASSERT_OK(err, "Add program to cpumap entry");
• err = bpf_map_lookup_elem(map_fd, &idx, &val);
• ASSERT_OK(err, "Read cpumap entry");
• ASSERT_EQ(info.id, val.bpf_prog.id, "Match program id to cpumap entry prog_id");
• /* attach dummy to other side to enable reception */
• cm_fd = bpf_program__fd(skel->progs.xdp_dummy_prog);
• err = bpf_xdp_attach(ifindex_dst, cm_fd, XDP_FLAGS_DRV_MODE, NULL);
• if (!ASSERT_OK(err, "Attach of dummy XDP"))

• goto out_close;
  

• /* 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(cm_fd_redir, &opts);
• ASSERT_OK(err, "XDP test run");
• /* wait for the packets to be flushed */
• kern_sync_rcu();
• err = bpf_xdp_detach(ifindex_src, XDP_FLAGS_DRV_MODE, NULL);
• ASSERT_OK(err, "XDP program detach");
• err = bpf_xdp_detach(ifindex_dst, XDP_FLAGS_DRV_MODE, NULL);
• ASSERT_OK(err, "XDP program detach");

+out_close:

• close_netns(nstoken);
• SYS_NOFAIL("ip netns del %s", TEST_NS);
• test_xdp_with_cpumap_helpers__destroy(skel);

+}

• void serial_test_xdp_cpumap_attach(void)

Thanks for improving the existing test by running in its netns, I also removed the "serial_". Applied. Thanks.

{ if (test__start_subtest("CPUMAP with programs in entries")) @@ -118,4 +225,7 @@ void serial_test_xdp_cpumap_attach(void) if (test__start_subtest("CPUMAP with frags programs in entries")) test_xdp_with_cpumap_frags_helpers();

• if (test__start_subtest("CPUMAP attach with programs in entries on veth"))

• test_xdp_with_cpumap_helpers_veth();
  

  }