bpf, sockmap: Test FIONREAD returns correct bytes in rx buffer with drops

When BPF program drops pkts the sockmap logic 'eats' the packet and
updates copied_seq. In the PASS case where the sk_buff is accepted
we update copied_seq from recvmsg path so we need a new test to
handle the drop case.

Original patch series broke this resulting in

test_sockmap_skb_verdict_fionread:PASS:ioctl(FIONREAD) error 0 nsec
test_sockmap_skb_verdict_fionread:FAIL:ioctl(FIONREAD) unexpected ioctl(FIONREAD): actual 1503041772 != expected 256

After updated patch with fix.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20230523025618.113937-14-john.fastabend@gmail.com

diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
index fe56049..064cc5e 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
@@ -11,6 +11,7 @@
 #include "test_sockmap_skb_verdict_attach.skel.h"
 #include "test_sockmap_progs_query.skel.h"
 #include "test_sockmap_pass_prog.skel.h"
+#include "test_sockmap_drop_prog.skel.h"
 #include "bpf_iter_sockmap.skel.h"
 
 #include "sockmap_helpers.h"
@@ -410,19 +411,31 @@ out:
        test_sockmap_pass_prog__destroy(skel);
 }
 
-static void test_sockmap_skb_verdict_fionread(void)
+static void test_sockmap_skb_verdict_fionread(bool pass_prog)
 {
+       int expected, zero = 0, sent, recvd, avail;
        int err, map, verdict, s, c0, c1, p0, p1;
-       struct test_sockmap_pass_prog *skel;
-       int zero = 0, sent, recvd, avail;
+       struct test_sockmap_pass_prog *pass;
+       struct test_sockmap_drop_prog *drop;
        char buf[256] = "0123456789";
 
-       skel = test_sockmap_pass_prog__open_and_load();
-       if (!ASSERT_OK_PTR(skel, "open_and_load"))
-               return;
+       if (pass_prog) {
+               pass = test_sockmap_pass_prog__open_and_load();
+               if (!ASSERT_OK_PTR(pass, "open_and_load"))
+                       return;
+               verdict = bpf_program__fd(pass->progs.prog_skb_verdict);
+               map = bpf_map__fd(pass->maps.sock_map_rx);
+               expected = sizeof(buf);
+       } else {
+               drop = test_sockmap_drop_prog__open_and_load();
+               if (!ASSERT_OK_PTR(drop, "open_and_load"))
+                       return;
+               verdict = bpf_program__fd(drop->progs.prog_skb_verdict);
+               map = bpf_map__fd(drop->maps.sock_map_rx);
+               /* On drop data is consumed immediately and copied_seq inc'd */
+               expected = 0;
+       }
 
-       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"))
@@ -443,9 +456,12 @@ static void test_sockmap_skb_verdict_fionread(void)
        ASSERT_EQ(sent, sizeof(buf), "xsend(p0)");
        err = ioctl(c1, FIONREAD, &avail);
        ASSERT_OK(err, "ioctl(FIONREAD) error");
-       ASSERT_EQ(avail, sizeof(buf), "ioctl(FIONREAD)");
-       recvd = recv_timeout(c1, &buf, sizeof(buf), SOCK_NONBLOCK, IO_TIMEOUT_SEC);
-       ASSERT_EQ(recvd, sizeof(buf), "recv_timeout(c0)");
+       ASSERT_EQ(avail, expected, "ioctl(FIONREAD)");
+       /* On DROP test there will be no data to read */
+       if (pass_prog) {
+               recvd = recv_timeout(c1, &buf, sizeof(buf), SOCK_NONBLOCK, IO_TIMEOUT_SEC);
+               ASSERT_EQ(recvd, sizeof(buf), "recv_timeout(c0)");
+       }
 
 out_close:
        close(c0);
@@ -453,7 +469,10 @@ out_close:
        close(c1);
        close(p1);
 out:
-       test_sockmap_pass_prog__destroy(skel);
+       if (pass_prog)
+               test_sockmap_pass_prog__destroy(pass);
+       else
+               test_sockmap_drop_prog__destroy(drop);
 }
 
 void test_sockmap_basic(void)
@@ -493,5 +512,7 @@ void test_sockmap_basic(void)
        if (test__start_subtest("sockmap skb_verdict shutdown"))
                test_sockmap_skb_verdict_shutdown();
        if (test__start_subtest("sockmap skb_verdict fionread"))
-               test_sockmap_skb_verdict_fionread();
+               test_sockmap_skb_verdict_fionread(true);
+       if (test__start_subtest("sockmap skb_verdict fionread on drop"))
+               test_sockmap_skb_verdict_fionread(false);
 }

diff --git a/tools/testing/selftests/bpf/progs/test_sockmap_drop_prog.c b/tools/testing/selftests/bpf/progs/test_sockmap_drop_prog.c
new file mode 100644 (file)
index 0000000..2931480
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_sockmap_drop_prog.c
@@ -0,0 +1,32 @@
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+
+struct {
+       __uint(type, BPF_MAP_TYPE_SOCKMAP);
+       __uint(max_entries, 20);
+       __type(key, int);
+       __type(value, int);
+} sock_map_rx SEC(".maps");
+
+struct {
+       __uint(type, BPF_MAP_TYPE_SOCKMAP);
+       __uint(max_entries, 20);
+       __type(key, int);
+       __type(value, int);
+} sock_map_tx SEC(".maps");
+
+struct {
+       __uint(type, BPF_MAP_TYPE_SOCKMAP);
+       __uint(max_entries, 20);
+       __type(key, int);
+       __type(value, int);
+} sock_map_msg SEC(".maps");
+
+SEC("sk_skb")
+int prog_skb_verdict(struct __sk_buff *skb)
+{
+       return SK_DROP;
+}
+
+char _license[] SEC("license") = "GPL";