Re: [PATCH bpf-next V10 7/7] bpf/selftests: tests using bpf_check_mtu BPF-helper
From: Andrii Nakryiko <hidden>
Date: 2020-12-22 18:59:05
Also in:
bpf
On Tue, Dec 22, 2020 at 8:23 AM Jesper Dangaard Brouer [off-list ref] wrote:
Adding selftest for BPF-helper bpf_check_mtu(). Making sure it can be used from both XDP and TC. V10: - Remove errno non-zero test in CHECK_ATTR() - Addresse comments from Andrii Nakryiko Signed-off-by: Jesper Dangaard Brouer <redacted> ---
Looks good, few minor nits below, feel free to address if you end up with another revision. Acked-by: Andrii Nakryiko <andrii@kernel.org>
quoted hunk ↗ jump to hunk
tools/testing/selftests/bpf/prog_tests/check_mtu.c | 218 ++++++++++++++++++++ tools/testing/selftests/bpf/progs/test_check_mtu.c | 199 ++++++++++++++++++ 2 files changed, 417 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/check_mtu.c create mode 100644 tools/testing/selftests/bpf/progs/test_check_mtu.cdiff --git a/tools/testing/selftests/bpf/prog_tests/check_mtu.c b/tools/testing/selftests/bpf/prog_tests/check_mtu.c new file mode 100644 index 000000000000..63f01c9e08d8 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/check_mtu.c@@ -0,0 +1,218 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2020 Jesper Dangaard Brouer */ + +#include <linux/if_link.h> /* before test_progs.h, avoid bpf_util.h redefines */ + +#include <test_progs.h> +#include "test_check_mtu.skel.h" +#include <network_helpers.h>
bit: test_progs and network_helpers should be included with "", not <>
+
+#include <stdlib.h>
+#include <inttypes.h>
+
+#define IFINDEX_LO 1
+
+static __u32 duration; /* Hint: needed for CHECK macro */
+
+static int read_mtu_device_lo(void)
+{
+ const char *filename = "/sys/class/net/lo/mtu";
+ char buf[11] = {};
+ int value;
+ int fd;
+
+ fd = open(filename, 0, O_RDONLY);
+ if (fd == -1)
+ return -1;
+
+ if (read(fd, buf, sizeof(buf)) == -1) {
+ close(fd);
+ return -2;
+ }
+ close(fd);nit: imo, simpler to write: err = read(...); close(fd); if (err == -1) return -2; This way you don't need to close twice. But it's very minor.
+ + value = strtoimax(buf, NULL, 10); + if (errno == ERANGE) + return -3; + + return value; +} +
[...]
+ CHECK(link_info.type != BPF_LINK_TYPE_XDP, "link_type", + "got %u != exp %u\n", link_info.type, BPF_LINK_TYPE_XDP); + CHECK(link_info.xdp.ifindex != IFINDEX_LO, "link_ifindex", + "got %u != exp %u\n", link_info.xdp.ifindex, IFINDEX_LO); + + err = bpf_link__detach(link); + CHECK(err, "link_detach", "failed %d\n", err); +
unless you explicitly want to test this force-detach, destroying the link (through destroying skeleton) would detach the program just fine.
+out: + test_check_mtu__destroy(skel); +} +
[...]
+
+SEC("xdp")
+int xdp_exceed_mtu(struct xdp_md *ctx)
+{
+ void *data_end = (void *)(long)ctx->data_end;
+ void *data = (void *)(long)ctx->data;
+ __u32 ifindex = GLOBAL_USER_IFINDEX;
+ __u32 data_len = data_end - data;
+ int retval = XDP_ABORTED; /* Fail */
+ __u32 mtu_len = 0;
+nit: unnecessary empty line inside variable declaration block
+ int delta;
+ int err;
+
+ /* Exceed MTU with 1 via delta adjust */
+ delta = GLOBAL_USER_MTU - (data_len - ETH_HLEN) + 1;
+
+ err = bpf_check_mtu(ctx, ifindex, &mtu_len, delta, 0);
+ if (err) {
+ retval = XDP_PASS; /* Success in exceeding MTU check */
+ if (err != BPF_MTU_CHK_RET_FRAG_NEEDED)
+ retval = XDP_DROP;
+ }
+
+ global_bpf_mtu_xdp = mtu_len;
+ return retval;
+}
+[...]