74 lines
1.6 KiB
C
74 lines
1.6 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2021 Facebook */
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#include <linux/bpf.h>
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#define BPF_NO_GLOBAL_DATA
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#include <bpf/bpf_helpers.h>
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char LICENSE[] SEC("license") = "GPL";
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__type(key, int);
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__type(value, int);
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__uint(max_entries, 1);
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} my_pid_map SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__type(key, int);
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__type(value, int);
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__uint(max_entries, 1);
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} res_map SEC(".maps");
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volatile int my_pid_var = 0;
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volatile int res_var = 0;
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SEC("tp/raw_syscalls/sys_enter")
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int handle_legacy(void *ctx)
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{
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int zero = 0, *my_pid, cur_pid, *my_res;
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my_pid = bpf_map_lookup_elem(&my_pid_map, &zero);
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if (!my_pid)
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return 1;
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cur_pid = bpf_get_current_pid_tgid() >> 32;
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if (cur_pid != *my_pid)
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return 1;
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my_res = bpf_map_lookup_elem(&res_map, &zero);
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if (!my_res)
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return 1;
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if (*my_res == 0)
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/* use bpf_printk() in combination with BPF_NO_GLOBAL_DATA to
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* force .rodata.str1.1 section that previously caused
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* problems on old kernels due to libbpf always tried to
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* create a global data map for it
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*/
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bpf_printk("Legacy-case bpf_printk test, pid %d\n", cur_pid);
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*my_res = 1;
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return *my_res;
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}
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SEC("tp/raw_syscalls/sys_enter")
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int handle_modern(void *ctx)
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{
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int zero = 0, cur_pid;
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cur_pid = bpf_get_current_pid_tgid() >> 32;
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if (cur_pid != my_pid_var)
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return 1;
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if (res_var == 0)
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/* we need bpf_printk() to validate libbpf logic around unused
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* global maps and legacy kernels; see comment in handle_legacy()
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*/
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bpf_printk("Modern-case bpf_printk test, pid %d\n", cur_pid);
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res_var = 1;
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return res_var;
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}
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