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selftests/bpf: Test freeing sockmap/sockhash with a socket in it 

Commit 7e81a35302 ("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: 7e81a35302 ("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
alistair/sensors
Jakub Sitnicki 2020-02-06 12:16:52 +01:00 committed by Daniel Borkmann
parent 0b2dc83906
commit 5d3919a953
1 changed files with 74 additions and 0 deletions
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74
tools/testing/selftests/bpf/prog_tests/sockmap_basic.c 100644
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@ -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);
}