selftests/bpf: Update sockopt_sk test to the use bpf_set_retval

The tests would break without this patch, because at one point it calls
  getsockopt(fd, SOL_TCP, TCP_ZEROCOPY_RECEIVE, &buf, &optlen)
This getsockopt receives the kernel-set -EINVAL. Prior to this patch
series, the eBPF getsockopt hook's -EPERM would override kernel's
-EINVAL, however, after this patch series, return 0's automatic
-EPERM will not; the eBPF prog has to explicitly bpf_set_retval(-EPERM)
if that is wanted.

I also removed the explicit mentions of EPERM in the comments in the
prog.

Signed-off-by: YiFei Zhu <zhuyifei@google.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/4f20b77cb46812dbc2bdcd7e3fa87c7573bde55e.1639619851.git.zhuyifei@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c b/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
index 4b937e5dbaca..30a99d2ed5c6 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
@@ -173,11 +173,11 @@ static int getsetsockopt(void)
 	}
 
 	memset(&buf, 0, sizeof(buf));
-	buf.zc.address = 12345; /* rejected by BPF */
+	buf.zc.address = 12345; /* Not page aligned. Rejected by tcp_zerocopy_receive() */
 	optlen = sizeof(buf.zc);
 	errno = 0;
 	err = getsockopt(fd, SOL_TCP, TCP_ZEROCOPY_RECEIVE, &buf, &optlen);
-	if (errno != EPERM) {
+	if (errno != EINVAL) {
 		log_err("Unexpected getsockopt(TCP_ZEROCOPY_RECEIVE) err=%d errno=%d",
 			err, errno);
 		goto err;