1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
3 
4 #ifndef _CGRP_KFUNC_COMMON_H
5 #define _CGRP_KFUNC_COMMON_H
6 
7 #include <errno.h>
8 #include <vmlinux.h>
9 #include <bpf/bpf_helpers.h>
10 #include <bpf/bpf_tracing.h>
11 
12 struct __cgrps_kfunc_map_value {
13 	struct cgroup __kptr * cgrp;
14 };
15 
16 struct hash_map {
17 	__uint(type, BPF_MAP_TYPE_HASH);
18 	__type(key, int);
19 	__type(value, struct __cgrps_kfunc_map_value);
20 	__uint(max_entries, 1);
21 } __cgrps_kfunc_map SEC(".maps");
22 
23 struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;
24 void bpf_cgroup_release(struct cgroup *p) __ksym;
25 struct cgroup *bpf_cgroup_ancestor(struct cgroup *cgrp, int level) __ksym;
26 struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
27 void bpf_rcu_read_lock(void) __ksym;
28 void bpf_rcu_read_unlock(void) __ksym;
29 
30 static inline struct __cgrps_kfunc_map_value *cgrps_kfunc_map_value_lookup(struct cgroup *cgrp)
31 {
32 	s32 id;
33 	long status;
34 
35 	status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
36 	if (status)
37 		return NULL;
38 
39 	return bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
40 }
41 
42 static inline int cgrps_kfunc_map_insert(struct cgroup *cgrp)
43 {
44 	struct __cgrps_kfunc_map_value local, *v;
45 	long status;
46 	struct cgroup *acquired, *old;
47 	s32 id;
48 
49 	status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
50 	if (status)
51 		return status;
52 
53 	local.cgrp = NULL;
54 	status = bpf_map_update_elem(&__cgrps_kfunc_map, &id, &local, BPF_NOEXIST);
55 	if (status)
56 		return status;
57 
58 	v = bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
59 	if (!v) {
60 		bpf_map_delete_elem(&__cgrps_kfunc_map, &id);
61 		return -ENOENT;
62 	}
63 
64 	acquired = bpf_cgroup_acquire(cgrp);
65 	if (!acquired) {
66 		bpf_map_delete_elem(&__cgrps_kfunc_map, &id);
67 		return -ENOENT;
68 	}
69 
70 	old = bpf_kptr_xchg(&v->cgrp, acquired);
71 	if (old) {
72 		bpf_cgroup_release(old);
73 		return -EEXIST;
74 	}
75 
76 	return 0;
77 }
78 
79 #endif /* _CGRP_KFUNC_COMMON_H */
80