72 lines
1.5 KiB
C
72 lines
1.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (C) 2023 Yafang Shao <laoar.shao@gmail.com> */
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#include "vmlinux.h"
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include <bpf/bpf_core_read.h>
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__u32 target_ancestor_level;
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__u64 target_ancestor_cgid;
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int target_pid, target_hid;
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struct cgroup *bpf_task_get_cgroup1(struct task_struct *task, int hierarchy_id) __ksym;
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struct cgroup *bpf_cgroup_ancestor(struct cgroup *cgrp, int level) __ksym;
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void bpf_cgroup_release(struct cgroup *cgrp) __ksym;
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static int bpf_link_create_verify(int cmd)
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{
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struct cgroup *cgrp, *ancestor;
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struct task_struct *task;
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int ret = 0;
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if (cmd != BPF_LINK_CREATE)
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return 0;
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task = bpf_get_current_task_btf();
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/* Then it can run in parallel with others */
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if (task->pid != target_pid)
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return 0;
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cgrp = bpf_task_get_cgroup1(task, target_hid);
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if (!cgrp)
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return 0;
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/* Refuse it if its cgid or its ancestor's cgid is the target cgid */
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if (cgrp->kn->id == target_ancestor_cgid)
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ret = -1;
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ancestor = bpf_cgroup_ancestor(cgrp, target_ancestor_level);
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if (!ancestor)
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goto out;
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if (ancestor->kn->id == target_ancestor_cgid)
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ret = -1;
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bpf_cgroup_release(ancestor);
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out:
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bpf_cgroup_release(cgrp);
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return ret;
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}
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SEC("lsm/bpf")
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int BPF_PROG(lsm_run, int cmd, union bpf_attr *attr, unsigned int size)
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{
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return bpf_link_create_verify(cmd);
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}
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SEC("lsm.s/bpf")
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int BPF_PROG(lsm_s_run, int cmd, union bpf_attr *attr, unsigned int size)
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{
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return bpf_link_create_verify(cmd);
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}
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SEC("fentry")
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int BPF_PROG(fentry_run)
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{
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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