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Subject[PATCH 5.4 24/96] selftests/bpf: Test freeing sockmap/sockhash with a socket in it
Date
From: Jakub Sitnicki <jakub@cloudflare.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@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200206111652.694507-4-jakub@cloudflare.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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);
+}

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