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-rw-r--r--tools/testing/selftests/bpf/progs/test_sysctl_prog.c70
1 files changed, 70 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/test_sysctl_prog.c b/tools/testing/selftests/bpf/progs/test_sysctl_prog.c
new file mode 100644
index 000000000000..a295cad805d7
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_sysctl_prog.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+
+#include <stdint.h>
+#include <string.h>
+
+#include <linux/stddef.h>
+#include <linux/bpf.h>
+
+#include "bpf_helpers.h"
+#include "bpf_util.h"
+
+/* Max supported length of a string with unsigned long in base 10 (pow2 - 1). */
+#define MAX_ULONG_STR_LEN 0xF
+
+/* Max supported length of sysctl value string (pow2). */
+#define MAX_VALUE_STR_LEN 0x40
+
+static __always_inline int is_tcp_mem(struct bpf_sysctl *ctx)
+{
+ char tcp_mem_name[] = "net/ipv4/tcp_mem";
+ unsigned char i;
+ char name[64];
+ int ret;
+
+ memset(name, 0, sizeof(name));
+ ret = bpf_sysctl_get_name(ctx, name, sizeof(name), 0);
+ if (ret < 0 || ret != sizeof(tcp_mem_name) - 1)
+ return 0;
+
+#pragma clang loop unroll(full)
+ for (i = 0; i < sizeof(tcp_mem_name); ++i)
+ if (name[i] != tcp_mem_name[i])
+ return 0;
+
+ return 1;
+}
+
+SEC("cgroup/sysctl")
+int sysctl_tcp_mem(struct bpf_sysctl *ctx)
+{
+ unsigned long tcp_mem[3] = {0, 0, 0};
+ char value[MAX_VALUE_STR_LEN];
+ unsigned char i, off = 0;
+ int ret;
+
+ if (ctx->write)
+ return 0;
+
+ if (!is_tcp_mem(ctx))
+ return 0;
+
+ ret = bpf_sysctl_get_current_value(ctx, value, MAX_VALUE_STR_LEN);
+ if (ret < 0 || ret >= MAX_VALUE_STR_LEN)
+ return 0;
+
+#pragma clang loop unroll(full)
+ for (i = 0; i < ARRAY_SIZE(tcp_mem); ++i) {
+ ret = bpf_strtoul(value + off, MAX_ULONG_STR_LEN, 0,
+ tcp_mem + i);
+ if (ret <= 0 || ret > MAX_ULONG_STR_LEN)
+ return 0;
+ off += ret & MAX_ULONG_STR_LEN;
+ }
+
+
+ return tcp_mem[0] < tcp_mem[1] && tcp_mem[1] < tcp_mem[2];
+}
+
+char _license[] SEC("license") = "GPL";