selftests/bpf: Tests using bpf_check_mtu BPF-helper input mtu_len param

Add tests that use mtu_len as input parameter in BPF-helper
bpf_check_mtu().

The BPF-helper is avail from both XDP and TC context. Add two tests
per context, one that tests below MTU and one that exceeds the MTU.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/161521556358.3515614.5915221479709358964.stgit@firesoul

diff --git a/tools/testing/selftests/bpf/prog_tests/check_mtu.c b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
index 36af1c1..b62a393 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/check_mtu.c
+++ b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
@@ -128,6 +128,8 @@ static void test_check_mtu_xdp(__u32 mtu, __u32 ifindex)
        test_check_mtu_run_xdp(skel, skel->progs.xdp_use_helper, mtu);
        test_check_mtu_run_xdp(skel, skel->progs.xdp_exceed_mtu, mtu);
        test_check_mtu_run_xdp(skel, skel->progs.xdp_minus_delta, mtu);
+       test_check_mtu_run_xdp(skel, skel->progs.xdp_input_len, mtu);
+       test_check_mtu_run_xdp(skel, skel->progs.xdp_input_len_exceed, mtu);
 
 cleanup:
        test_check_mtu__destroy(skel);
@@ -187,6 +189,8 @@ static void test_check_mtu_tc(__u32 mtu, __u32 ifindex)
        test_check_mtu_run_tc(skel, skel->progs.tc_exceed_mtu, mtu);
        test_check_mtu_run_tc(skel, skel->progs.tc_exceed_mtu_da, mtu);
        test_check_mtu_run_tc(skel, skel->progs.tc_minus_delta, mtu);
+       test_check_mtu_run_tc(skel, skel->progs.tc_input_len, mtu);
+       test_check_mtu_run_tc(skel, skel->progs.tc_input_len_exceed, mtu);
 cleanup:
        test_check_mtu__destroy(skel);
 }

diff --git a/tools/testing/selftests/bpf/progs/test_check_mtu.c b/tools/testing/selftests/bpf/progs/test_check_mtu.c
index b7787b4..c4a9bae 100644 (file)
--- a/tools/testing/selftests/bpf/progs/test_check_mtu.c
+++ b/tools/testing/selftests/bpf/progs/test_check_mtu.c
@@ -105,6 +105,54 @@ int xdp_minus_delta(struct xdp_md *ctx)
        return retval;
 }
 
+SEC("xdp")
+int xdp_input_len(struct xdp_md *ctx)
+{
+       int retval = XDP_PASS; /* Expected retval on successful test */
+       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;
+
+       /* API allow user give length to check as input via mtu_len param,
+        * resulting MTU value is still output in mtu_len param after call.
+        *
+        * Input len is L3, like MTU and iph->tot_len.
+        * Remember XDP data_len is L2.
+        */
+       __u32 mtu_len = data_len - ETH_HLEN;
+
+       if (bpf_check_mtu(ctx, ifindex, &mtu_len, 0, 0))
+               retval = XDP_ABORTED;
+
+       global_bpf_mtu_xdp = mtu_len;
+       return retval;
+}
+
+SEC("xdp")
+int xdp_input_len_exceed(struct xdp_md *ctx)
+{
+       int retval = XDP_ABORTED; /* Fail */
+       __u32 ifindex = GLOBAL_USER_IFINDEX;
+       int err;
+
+       /* API allow user give length to check as input via mtu_len param,
+        * resulting MTU value is still output in mtu_len param after call.
+        *
+        * Input length value is L3 size like MTU.
+        */
+       __u32 mtu_len = GLOBAL_USER_MTU;
+
+       mtu_len += 1; /* Exceed with 1 */
+
+       err = bpf_check_mtu(ctx, ifindex, &mtu_len, 0, 0);
+       if (err == BPF_MTU_CHK_RET_FRAG_NEEDED)
+               retval = XDP_PASS ; /* Success in exceeding MTU check */
+
+       global_bpf_mtu_xdp = mtu_len;
+       return retval;
+}
+
 SEC("classifier")
 int tc_use_helper(struct __sk_buff *ctx)
 {
@@ -196,3 +244,47 @@ int tc_minus_delta(struct __sk_buff *ctx)
        global_bpf_mtu_xdp = mtu_len;
        return retval;
 }
+
+SEC("classifier")
+int tc_input_len(struct __sk_buff *ctx)
+{
+       int retval = BPF_OK; /* Expected retval on successful test */
+       __u32 ifindex = GLOBAL_USER_IFINDEX;
+
+       /* API allow user give length to check as input via mtu_len param,
+        * resulting MTU value is still output in mtu_len param after call.
+        *
+        * Input length value is L3 size.
+        */
+       __u32 mtu_len = GLOBAL_USER_MTU;
+
+       if (bpf_check_mtu(ctx, ifindex, &mtu_len, 0, 0))
+               retval = BPF_DROP;
+
+       global_bpf_mtu_xdp = mtu_len;
+       return retval;
+}
+
+SEC("classifier")
+int tc_input_len_exceed(struct __sk_buff *ctx)
+{
+       int retval = BPF_DROP; /* Fail */
+       __u32 ifindex = GLOBAL_USER_IFINDEX;
+       int err;
+
+       /* API allow user give length to check as input via mtu_len param,
+        * resulting MTU value is still output in mtu_len param after call.
+        *
+        * Input length value is L3 size like MTU.
+        */
+       __u32 mtu_len = GLOBAL_USER_MTU;
+
+       mtu_len += 1; /* Exceed with 1 */
+
+       err = bpf_check_mtu(ctx, ifindex, &mtu_len, 0, 0);
+       if (err == BPF_MTU_CHK_RET_FRAG_NEEDED)
+               retval = BPF_OK; /* Success in exceeding MTU check */
+
+       global_bpf_mtu_xdp = mtu_len;
+       return retval;
+}