126 lines
2.7 KiB
C
126 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
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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_misc.h"
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char _license[] SEC("license") = "GPL";
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struct {
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__uint(type, BPF_MAP_TYPE_CGRP_STORAGE);
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__uint(map_flags, BPF_F_NO_PREALLOC);
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__type(key, int);
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__type(value, long);
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} map_a SEC(".maps");
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__s32 target_pid;
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__u64 cgroup_id;
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int target_hid;
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bool is_cgroup1;
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struct cgroup *bpf_task_get_cgroup1(struct task_struct *task, int hierarchy_id) __ksym;
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void bpf_cgroup_release(struct cgroup *cgrp) __ksym;
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void bpf_rcu_read_lock(void) __ksym;
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void bpf_rcu_read_unlock(void) __ksym;
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SEC("?iter.s/cgroup")
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int cgroup_iter(struct bpf_iter__cgroup *ctx)
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{
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struct cgroup *cgrp = ctx->cgroup;
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long *ptr;
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if (cgrp == NULL)
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return 0;
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ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,
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BPF_LOCAL_STORAGE_GET_F_CREATE);
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if (ptr)
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cgroup_id = cgrp->kn->id;
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return 0;
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}
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static void __no_rcu_lock(struct cgroup *cgrp)
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{
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long *ptr;
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/* Note that trace rcu is held in sleepable prog, so we can use
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* bpf_cgrp_storage_get() in sleepable prog.
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*/
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ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0,
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BPF_LOCAL_STORAGE_GET_F_CREATE);
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if (ptr)
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cgroup_id = cgrp->kn->id;
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}
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SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
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int cgrp1_no_rcu_lock(void *ctx)
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{
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struct task_struct *task;
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struct cgroup *cgrp;
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task = bpf_get_current_task_btf();
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if (task->pid != target_pid)
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return 0;
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/* bpf_task_get_cgroup1 can work in sleepable prog */
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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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__no_rcu_lock(cgrp);
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bpf_cgroup_release(cgrp);
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return 0;
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}
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SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
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int no_rcu_lock(void *ctx)
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{
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struct task_struct *task;
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task = bpf_get_current_task_btf();
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if (task->pid != target_pid)
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return 0;
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/* task->cgroups is untrusted in sleepable prog outside of RCU CS */
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__no_rcu_lock(task->cgroups->dfl_cgrp);
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return 0;
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}
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SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
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int yes_rcu_lock(void *ctx)
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{
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struct task_struct *task;
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struct cgroup *cgrp;
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long *ptr;
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task = bpf_get_current_task_btf();
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if (task->pid != target_pid)
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return 0;
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if (is_cgroup1) {
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bpf_rcu_read_lock();
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cgrp = bpf_task_get_cgroup1(task, target_hid);
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if (!cgrp) {
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bpf_rcu_read_unlock();
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return 0;
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}
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ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE);
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if (ptr)
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cgroup_id = cgrp->kn->id;
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bpf_cgroup_release(cgrp);
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bpf_rcu_read_unlock();
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return 0;
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}
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bpf_rcu_read_lock();
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cgrp = task->cgroups->dfl_cgrp;
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/* cgrp is trusted under RCU CS */
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ptr = bpf_cgrp_storage_get(&map_a, cgrp, 0, BPF_LOCAL_STORAGE_GET_F_CREATE);
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if (ptr)
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cgroup_id = cgrp->kn->id;
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bpf_rcu_read_unlock();
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return 0;
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}
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