[PATCH bpf v5 12/12] bpf: sockmap, test FIONREAD returns correct bytes in rx buffer with drops

John Fastabend
2023-04-06T01:02:01Z

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
#176/17 sockmap_basic/sockmap skb_verdict fionread on drop:FAIL

After updated patch with fix.

#176/16 sockmap_basic/sockmap skb_verdict fionread:OK
#176/17 sockmap_basic/sockmap skb_verdict fionread on drop:OK

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
---
.../selftests/bpf/prog_tests/sockmap_basic.c | 47 ++++++++++++++-----
.../bpf/progs/test_sockmap_drop_prog.c | 32 +++++++++++++
2 files changed, 66 insertions(+), 13 deletions(-)
create mode 100644 tools/testing/selftests/bpf/progs/test_sockmap_drop_prog.c

diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
index 322b5a135740..10112a1ab443 100644
--- 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"
@@ -416,19 +417,31 @@ static void test_sockmap_skb_verdict_shutdown(void)
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"))
@@ -449,9 +462,12 @@ 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);
@@ -459,7 +475,10 @@ static void test_sockmap_skb_verdict_fionread(void)
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)
@@ -499,5 +518,7 @@ 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
index 000000000000..29314805ce42
--- /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";
--
2.33.0