linux-kernel - [PATCH 5.4 24/96] selftests/bpf: Test freeing sockmap/sockhash with a socket in it

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Date:   Thu, 13 Feb 2020 07:20:31 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jakub Sitnicki <jakub@...udflare.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        John Fastabend <john.fastabend@...il.com>
Subject: [PATCH 5.4 24/96] selftests/bpf: Test freeing sockmap/sockhash with a socket in it

From: Jakub Sitnicki <jakub@...udflare.com>

commit 5d3919a953c3c96c02fc7a337f8376cde43ae31f upstream.

Commit 7e81a3530206 ("bpf: Sockmap, ensure sock lock held during tear
down") introduced sleeping issues inside RCU critical sections and while
holding a spinlock on sockmap/sockhash tear-down. There has to be at least
one socket in the map for the problem to surface.

This adds a test that triggers the warnings for broken locking rules. Not a
fix per se, but rather tooling to verify the accompanying fixes. Run on a
VM with 1 vCPU to reproduce the warnings.

Fixes: 7e81a3530206 ("bpf: Sockmap, ensure sock lock held during tear down")
Signed-off-by: Jakub Sitnicki <jakub@...udflare.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Acked-by: John Fastabend <john.fastabend@...il.com>
Link: https://lore.kernel.org/bpf/20200206111652.694507-4-jakub@cloudflare.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 tools/testing/selftests/bpf/prog_tests/sockmap_basic.c |   74 +++++++++++++++++
 1 file changed, 74 insertions(+)

--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2020 Cloudflare
+
+#include "test_progs.h"
+
+static int connected_socket_v4(void)
+{
+	struct sockaddr_in addr = {
+		.sin_family = AF_INET,
+		.sin_port = htons(80),
+		.sin_addr = { inet_addr("127.0.0.1") },
+	};
+	socklen_t len = sizeof(addr);
+	int s, repair, err;
+
+	s = socket(AF_INET, SOCK_STREAM, 0);
+	if (CHECK_FAIL(s == -1))
+		goto error;
+
+	repair = TCP_REPAIR_ON;
+	err = setsockopt(s, SOL_TCP, TCP_REPAIR, &repair, sizeof(repair));
+	if (CHECK_FAIL(err))
+		goto error;
+
+	err = connect(s, (struct sockaddr *)&addr, len);
+	if (CHECK_FAIL(err))
+		goto error;
+
+	repair = TCP_REPAIR_OFF_NO_WP;
+	err = setsockopt(s, SOL_TCP, TCP_REPAIR, &repair, sizeof(repair));
+	if (CHECK_FAIL(err))
+		goto error;
+
+	return s;
+error:
+	perror(__func__);
+	close(s);
+	return -1;
+}
+
+/* Create a map, populate it with one socket, and free the map. */
+static void test_sockmap_create_update_free(enum bpf_map_type map_type)
+{
+	const int zero = 0;
+	int s, map, err;
+
+	s = connected_socket_v4();
+	if (CHECK_FAIL(s == -1))
+		return;
+
+	map = bpf_create_map(map_type, sizeof(int), sizeof(int), 1, 0);
+	if (CHECK_FAIL(map == -1)) {
+		perror("bpf_create_map");
+		goto out;
+	}
+
+	err = bpf_map_update_elem(map, &zero, &s, BPF_NOEXIST);
+	if (CHECK_FAIL(err)) {
+		perror("bpf_map_update");
+		goto out;
+	}
+
+out:
+	close(map);
+	close(s);
+}
+
+void test_sockmap_basic(void)
+{
+	if (test__start_subtest("sockmap create_update_free"))
+		test_sockmap_create_update_free(BPF_MAP_TYPE_SOCKMAP);
+	if (test__start_subtest("sockhash create_update_free"))
+		test_sockmap_create_update_free(BPF_MAP_TYPE_SOCKHASH);
+}