227a89cf50
bpf_cgroup_ancestor() allows BPF programs to access the ancestor of a struct cgroup *. This patch adds selftests that validate its expected behavior. Signed-off-by: David Vernet <void@manifault.com> Link: https://lore.kernel.org/r/20221122055458.173143-5-void@manifault.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
72 lines
1.7 KiB
C
72 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
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#ifndef _CGRP_KFUNC_COMMON_H
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#define _CGRP_KFUNC_COMMON_H
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#include <errno.h>
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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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struct __cgrps_kfunc_map_value {
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struct cgroup __kptr_ref * cgrp;
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};
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struct hash_map {
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__uint(type, BPF_MAP_TYPE_HASH);
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__type(key, int);
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__type(value, struct __cgrps_kfunc_map_value);
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__uint(max_entries, 1);
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} __cgrps_kfunc_map SEC(".maps");
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struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;
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struct cgroup *bpf_cgroup_kptr_get(struct cgroup **pp) __ksym;
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void bpf_cgroup_release(struct cgroup *p) __ksym;
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struct cgroup *bpf_cgroup_ancestor(struct cgroup *cgrp, int level) __ksym;
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static inline struct __cgrps_kfunc_map_value *cgrps_kfunc_map_value_lookup(struct cgroup *cgrp)
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{
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s32 id;
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long status;
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status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
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if (status)
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return NULL;
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return bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
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}
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static inline int cgrps_kfunc_map_insert(struct cgroup *cgrp)
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{
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struct __cgrps_kfunc_map_value local, *v;
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long status;
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struct cgroup *acquired, *old;
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s32 id;
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status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
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if (status)
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return status;
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local.cgrp = NULL;
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status = bpf_map_update_elem(&__cgrps_kfunc_map, &id, &local, BPF_NOEXIST);
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if (status)
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return status;
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v = bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
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if (!v) {
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bpf_map_delete_elem(&__cgrps_kfunc_map, &id);
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return -ENOENT;
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}
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acquired = bpf_cgroup_acquire(cgrp);
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old = bpf_kptr_xchg(&v->cgrp, acquired);
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if (old) {
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bpf_cgroup_release(old);
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return -EEXIST;
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}
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return 0;
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}
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#endif /* _CGRP_KFUNC_COMMON_H */
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