81 lines
1.7 KiB
C
81 lines
1.7 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
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#include "bpf_iter.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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__u32 target_pid;
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__u64 cgroup_id;
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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 seq_file *seq = ctx->meta->seq;
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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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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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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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/* ptr_to_btf_id semantics. should work. */
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cgrp = task->cgroups->dfl_cgrp;
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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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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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bpf_rcu_read_lock();
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cgrp = task->cgroups->dfl_cgrp;
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/* cgrp is untrusted and cannot pass to bpf_cgrp_storage_get() helper. */
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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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