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1// SPDX-License-Identifier: GPL-2.02/* Copyright (C) 2023 Yafang Shao <laoar.shao@gmail.com> */3 4#include "vmlinux.h"5#include <bpf/bpf_helpers.h>6#include <bpf/bpf_tracing.h>7#include <bpf/bpf_core_read.h>8 9__u32 target_ancestor_level;10__u64 target_ancestor_cgid;11int target_pid, target_hid;12 13struct cgroup *bpf_task_get_cgroup1(struct task_struct *task, int hierarchy_id) __ksym;14struct cgroup *bpf_cgroup_ancestor(struct cgroup *cgrp, int level) __ksym;15void bpf_cgroup_release(struct cgroup *cgrp) __ksym;16 17static int bpf_link_create_verify(int cmd)18{19 struct cgroup *cgrp, *ancestor;20 struct task_struct *task;21 int ret = 0;22 23 if (cmd != BPF_LINK_CREATE)24 return 0;25 26 task = bpf_get_current_task_btf();27 28 /* Then it can run in parallel with others */29 if (task->pid != target_pid)30 return 0;31 32 cgrp = bpf_task_get_cgroup1(task, target_hid);33 if (!cgrp)34 return 0;35 36 /* Refuse it if its cgid or its ancestor's cgid is the target cgid */37 if (cgrp->kn->id == target_ancestor_cgid)38 ret = -1;39 40 ancestor = bpf_cgroup_ancestor(cgrp, target_ancestor_level);41 if (!ancestor)42 goto out;43 44 if (ancestor->kn->id == target_ancestor_cgid)45 ret = -1;46 bpf_cgroup_release(ancestor);47 48out:49 bpf_cgroup_release(cgrp);50 return ret;51}52 53SEC("lsm/bpf")54int BPF_PROG(lsm_run, int cmd, union bpf_attr *attr, unsigned int size)55{56 return bpf_link_create_verify(cmd);57}58 59SEC("lsm.s/bpf")60int BPF_PROG(lsm_s_run, int cmd, union bpf_attr *attr, unsigned int size)61{62 return bpf_link_create_verify(cmd);63}64 65SEC("fentry")66int BPF_PROG(fentry_run)67{68 return 0;69}70 71char _license[] SEC("license") = "GPL";72