1// SPDX-License-Identifier: GPL-2.0
 2// Copyright (c) 2019 Facebook
 3
 4#include <stdint.h>
 5#include <string.h>
 6
 7#include <linux/stddef.h>
 8#include <linux/bpf.h>
 9
10#include <bpf/bpf_helpers.h>
11
12#ifndef ARRAY_SIZE
13#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
14#endif
15
16/* tcp_mem sysctl has only 3 ints, but this test is doing TCP_MEM_LOOPS */
17#define TCP_MEM_LOOPS 20  /* because 30 doesn't fit into 512 bytes of stack */
18#define MAX_ULONG_STR_LEN 7
19#define MAX_VALUE_STR_LEN (TCP_MEM_LOOPS * MAX_ULONG_STR_LEN)
20
 
21static __attribute__((noinline)) int is_tcp_mem(struct bpf_sysctl *ctx)
22{
23	volatile char tcp_mem_name[] = "net/ipv4/tcp_mem/very_very_very_very_long_pointless_string_to_stress_byte_loop";
24	unsigned char i;
25	char name[64];
26	int ret;
27
28	memset(name, 0, sizeof(name));
29	ret = bpf_sysctl_get_name(ctx, name, sizeof(name), 0);
30	if (ret < 0 || ret != sizeof(tcp_mem_name) - 1)
31		return 0;
32
33#pragma clang loop unroll(disable)
34	for (i = 0; i < sizeof(tcp_mem_name); ++i)
35		if (name[i] != tcp_mem_name[i])
36			return 0;
37
38	return 1;
39}
40
41
42SEC("cgroup/sysctl")
43int sysctl_tcp_mem(struct bpf_sysctl *ctx)
44{
45	unsigned long tcp_mem[TCP_MEM_LOOPS] = {};
46	char value[MAX_VALUE_STR_LEN];
47	unsigned char i, off = 0;
48	int ret;
49
50	if (ctx->write)
51		return 0;
52
53	if (!is_tcp_mem(ctx))
54		return 0;
55
56	ret = bpf_sysctl_get_current_value(ctx, value, MAX_VALUE_STR_LEN);
57	if (ret < 0 || ret >= MAX_VALUE_STR_LEN)
58		return 0;
59
60#pragma clang loop unroll(disable)
61	for (i = 0; i < ARRAY_SIZE(tcp_mem); ++i) {
62		ret = bpf_strtoul(value + off, MAX_ULONG_STR_LEN, 0,
63				  tcp_mem + i);
64		if (ret <= 0 || ret > MAX_ULONG_STR_LEN)
65			return 0;
66		off += ret & MAX_ULONG_STR_LEN;
67	}
68
69	return tcp_mem[0] < tcp_mem[1] && tcp_mem[1] < tcp_mem[2];
70}
71
72char _license[] SEC("license") = "GPL";

 1// SPDX-License-Identifier: GPL-2.0
 2// Copyright (c) 2019 Facebook
 3
 4#include <stdint.h>
 5#include <string.h>
 6
 7#include <linux/stddef.h>
 8#include <linux/bpf.h>
 9
10#include <bpf/bpf_helpers.h>
11
12#ifndef ARRAY_SIZE
13#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
14#endif
15
16/* tcp_mem sysctl has only 3 ints, but this test is doing TCP_MEM_LOOPS */
17#define TCP_MEM_LOOPS 20  /* because 30 doesn't fit into 512 bytes of stack */
18#define MAX_ULONG_STR_LEN 7
19#define MAX_VALUE_STR_LEN (TCP_MEM_LOOPS * MAX_ULONG_STR_LEN)
20
21const char tcp_mem_name[] = "net/ipv4/tcp_mem/very_very_very_very_long_pointless_string_to_stress_byte_loop";
22static __attribute__((noinline)) int is_tcp_mem(struct bpf_sysctl *ctx)
23{
 
24	unsigned char i;
25	char name[sizeof(tcp_mem_name)];
26	int ret;
27
28	memset(name, 0, sizeof(name));
29	ret = bpf_sysctl_get_name(ctx, name, sizeof(name), 0);
30	if (ret < 0 || ret != sizeof(tcp_mem_name) - 1)
31		return 0;
32
33#pragma clang loop unroll(disable)
34	for (i = 0; i < sizeof(tcp_mem_name); ++i)
35		if (name[i] != tcp_mem_name[i])
36			return 0;
37
38	return 1;
39}
40
41
42SEC("cgroup/sysctl")
43int sysctl_tcp_mem(struct bpf_sysctl *ctx)
44{
45	unsigned long tcp_mem[TCP_MEM_LOOPS] = {};
46	char value[MAX_VALUE_STR_LEN];
47	unsigned char i, off = 0;
48	int ret;
49
50	if (ctx->write)
51		return 0;
52
53	if (!is_tcp_mem(ctx))
54		return 0;
55
56	ret = bpf_sysctl_get_current_value(ctx, value, MAX_VALUE_STR_LEN);
57	if (ret < 0 || ret >= MAX_VALUE_STR_LEN)
58		return 0;
59
60#pragma clang loop unroll(disable)
61	for (i = 0; i < ARRAY_SIZE(tcp_mem); ++i) {
62		ret = bpf_strtoul(value + off, MAX_ULONG_STR_LEN, 0,
63				  tcp_mem + i);
64		if (ret <= 0 || ret > MAX_ULONG_STR_LEN)
65			return 0;
66		off += ret & MAX_ULONG_STR_LEN;
67	}
68
69	return tcp_mem[0] < tcp_mem[1] && tcp_mem[1] < tcp_mem[2];
70}
71
72char _license[] SEC("license") = "GPL";