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This test has a BPF program which writes the last known pid to call the sync syscall within a given cgroup to a map. The user mode program creates its own mount namespace, and mounts the cgroupsv2 hierarchy in there, as on all current test systems (Ubuntu 16.04, Debian), the cgroupsv2 vfs is unmounted by default. Once it does this, it proceeds to test. The test checks for positive and negative condition. It ensures that when it's part of a given cgroup, its pid is captured in the map, and that when it leaves the cgroup, this doesn't happen. It populate a cgroups arraymap prior to execution in userspace. This means that the program must be run in the same cgroups namespace as the programs that are being traced. Signed-off-by: Sargun Dhillon <sargun@sargun.me> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Tejun Heo <tj@kernel.org> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
43 lines
1.1 KiB
C
43 lines
1.1 KiB
C
/* Copyright (c) 2016 Sargun Dhillon <sargun@sargun.me>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#include <linux/ptrace.h>
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#include <uapi/linux/bpf.h>
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#include <linux/version.h>
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#include "bpf_helpers.h"
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#include <uapi/linux/utsname.h>
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struct bpf_map_def SEC("maps") cgroup_map = {
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.type = BPF_MAP_TYPE_CGROUP_ARRAY,
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.key_size = sizeof(u32),
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.value_size = sizeof(u32),
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.max_entries = 1,
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};
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struct bpf_map_def SEC("maps") perf_map = {
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.type = BPF_MAP_TYPE_ARRAY,
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.key_size = sizeof(u32),
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.value_size = sizeof(u64),
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.max_entries = 1,
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};
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/* Writes the last PID that called sync to a map at index 0 */
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SEC("kprobe/sys_sync")
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int bpf_prog1(struct pt_regs *ctx)
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{
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u64 pid = bpf_get_current_pid_tgid();
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int idx = 0;
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if (!bpf_current_task_under_cgroup(&cgroup_map, 0))
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return 0;
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bpf_map_update_elem(&perf_map, &idx, &pid, BPF_ANY);
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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u32 _version SEC("version") = LINUX_VERSION_CODE;
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