selftests/bpf: Test for map update access from within EXT programs

This adds further tests to ensure access permissions and restrictions
are applied properly for some map types such as sock-map.
It also adds another negative tests to assert static functions cannot be
replaced. In the 'unreliable' mode it still fails with error 'tracing progs
cannot use bpf_spin_lock yet' with the change in the verifier

Signed-off-by: Udip Pant <udippant@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200825232003.2877030-5-udippant@fb.com

1 files changed, 34 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/freplace_cls_redirect.c b/tools/testing/selftests/bpf/progs/freplace_cls_redirect.c
new file mode 100644
index 000000000000..68a5a9db928a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/freplace_cls_redirect.c
@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2020 Facebook
+
+#include <linux/stddef.h>
+#include <linux/bpf.h>
+#include <linux/pkt_cls.h>
+#include <bpf/bpf_endian.h>
+#include <bpf/bpf_helpers.h>
+
+struct bpf_map_def SEC("maps") sock_map = {
+	.type = BPF_MAP_TYPE_SOCKMAP,
+	.key_size = sizeof(int),
+	.value_size = sizeof(int),
+	.max_entries = 2,
+};
+
+SEC("freplace/cls_redirect")
+int freplace_cls_redirect_test(struct __sk_buff *skb)
+{
+	int ret = 0;
+	const int zero = 0;
+	struct bpf_sock *sk;
+
+	sk = bpf_map_lookup_elem(&sock_map, &zero);
+	if (!sk)
+		return TC_ACT_SHOT;
+
+	ret = bpf_map_update_elem(&sock_map, &zero, sk, 0);
+	bpf_sk_release(sk);
+
+	return ret == 0 ? TC_ACT_OK : TC_ACT_SHOT;
+}
+
+char _license[] SEC("license") = "GPL";