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193 lines · 4.9 KiB

1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
4 */
5
6#include <linux/types.h>
7#include <linux/bpf.h>
8#include <linux/bpf_local_storage.h>
9#include <uapi/linux/btf.h>
10#include <linux/btf_ids.h>
11
12DEFINE_BPF_STORAGE_CACHE(cgroup_cache);
13
14static struct bpf_local_storage __rcu **cgroup_storage_ptr(void *owner)
15{
16 struct cgroup *cg = owner;
17
18 return &cg->bpf_cgrp_storage;
19}
20
21void bpf_cgrp_storage_free(struct cgroup *cgroup)
22{
23 struct bpf_local_storage *local_storage;
24
25 rcu_read_lock();
26 local_storage = rcu_dereference(cgroup->bpf_cgrp_storage);
27 if (!local_storage)
28 goto out;
29
30 bpf_local_storage_destroy(local_storage);
31out:
32 rcu_read_unlock();
33}
34
35static struct bpf_local_storage_data *
36cgroup_storage_lookup(struct cgroup *cgroup, struct bpf_map *map, bool cacheit_lockit)
37{
38 struct bpf_local_storage *cgroup_storage;
39 struct bpf_local_storage_map *smap;
40
41 cgroup_storage = rcu_dereference_check(cgroup->bpf_cgrp_storage,
42 bpf_rcu_lock_held());
43 if (!cgroup_storage)
44 return NULL;
45
46 smap = (struct bpf_local_storage_map *)map;
47 return bpf_local_storage_lookup(cgroup_storage, smap, cacheit_lockit);
48}
49
50static void *bpf_cgrp_storage_lookup_elem(struct bpf_map *map, void *key)
51{
52 struct bpf_local_storage_data *sdata;
53 struct cgroup *cgroup;
54 int fd;
55
56 fd = *(int *)key;
57 cgroup = cgroup_v1v2_get_from_fd(fd);
58 if (IS_ERR(cgroup))
59 return ERR_CAST(cgroup);
60
61 sdata = cgroup_storage_lookup(cgroup, map, true);
62 cgroup_put(cgroup);
63 return sdata ? sdata->data : NULL;
64}
65
66static long bpf_cgrp_storage_update_elem(struct bpf_map *map, void *key,
67 void *value, u64 map_flags)
68{
69 struct bpf_local_storage_data *sdata;
70 struct cgroup *cgroup;
71 int fd;
72
73 fd = *(int *)key;
74 cgroup = cgroup_v1v2_get_from_fd(fd);
75 if (IS_ERR(cgroup))
76 return PTR_ERR(cgroup);
77
78 sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map,
79 value, map_flags, false);
80 cgroup_put(cgroup);
81 return PTR_ERR_OR_ZERO(sdata);
82}
83
84static int cgroup_storage_delete(struct cgroup *cgroup, struct bpf_map *map)
85{
86 struct bpf_local_storage_data *sdata;
87
88 sdata = cgroup_storage_lookup(cgroup, map, false);
89 if (!sdata)
90 return -ENOENT;
91
92 return bpf_selem_unlink(SELEM(sdata));
93}
94
95static long bpf_cgrp_storage_delete_elem(struct bpf_map *map, void *key)
96{
97 struct cgroup *cgroup;
98 int err, fd;
99
100 fd = *(int *)key;
101 cgroup = cgroup_v1v2_get_from_fd(fd);
102 if (IS_ERR(cgroup))
103 return PTR_ERR(cgroup);
104
105 err = cgroup_storage_delete(cgroup, map);
106 cgroup_put(cgroup);
107 return err;
108}
109
110static int notsupp_get_next_key(struct bpf_map *map, void *key, void *next_key)
111{
112 return -ENOTSUPP;
113}
114
115static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr)
116{
117 return bpf_local_storage_map_alloc(attr, &cgroup_cache);
118}
119
120static void cgroup_storage_map_free(struct bpf_map *map)
121{
122 bpf_local_storage_map_free(map, &cgroup_cache);
123}
124
125BPF_CALL_4(bpf_cgrp_storage_get, struct bpf_map *, map, struct cgroup *, cgroup,
126 void *, value, u64, flags)
127{
128 struct bpf_local_storage_data *sdata;
129
130 WARN_ON_ONCE(!bpf_rcu_lock_held());
131 if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
132 return (unsigned long)NULL;
133
134 if (!cgroup)
135 return (unsigned long)NULL;
136
137 sdata = cgroup_storage_lookup(cgroup, map, true);
138 if (sdata)
139 goto out;
140
141 /* only allocate new storage, when the cgroup is refcounted */
142 if (!percpu_ref_is_dying(&cgroup->self.refcnt) &&
143 (flags & BPF_LOCAL_STORAGE_GET_F_CREATE))
144 sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map,
145 value, BPF_NOEXIST, false);
146
147out:
148 return IS_ERR_OR_NULL(sdata) ? (unsigned long)NULL : (unsigned long)sdata->data;
149}
150
151BPF_CALL_2(bpf_cgrp_storage_delete, struct bpf_map *, map, struct cgroup *, cgroup)
152{
153 WARN_ON_ONCE(!bpf_rcu_lock_held());
154 if (!cgroup)
155 return -EINVAL;
156
157 return cgroup_storage_delete(cgroup, map);
158}
159
160const struct bpf_map_ops cgrp_storage_map_ops = {
161 .map_meta_equal = bpf_map_meta_equal,
162 .map_alloc_check = bpf_local_storage_map_alloc_check,
163 .map_alloc = cgroup_storage_map_alloc,
164 .map_free = cgroup_storage_map_free,
165 .map_get_next_key = notsupp_get_next_key,
166 .map_lookup_elem = bpf_cgrp_storage_lookup_elem,
167 .map_update_elem = bpf_cgrp_storage_update_elem,
168 .map_delete_elem = bpf_cgrp_storage_delete_elem,
169 .map_check_btf = bpf_local_storage_map_check_btf,
170 .map_mem_usage = bpf_local_storage_map_mem_usage,
171 .map_btf_id = &bpf_local_storage_map_btf_id[0],
172 .map_owner_storage_ptr = cgroup_storage_ptr,
173};
174
175const struct bpf_func_proto bpf_cgrp_storage_get_proto = {
176 .func = bpf_cgrp_storage_get,
177 .gpl_only = false,
178 .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
179 .arg1_type = ARG_CONST_MAP_PTR,
180 .arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL,
181 .arg2_btf_id = &bpf_cgroup_btf_id[0],
182 .arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,
183 .arg4_type = ARG_ANYTHING,
184};
185
186const struct bpf_func_proto bpf_cgrp_storage_delete_proto = {
187 .func = bpf_cgrp_storage_delete,
188 .gpl_only = false,
189 .ret_type = RET_INTEGER,
190 .arg1_type = ARG_CONST_MAP_PTR,
191 .arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL,
192 .arg2_btf_id = &bpf_cgroup_btf_id[0],
193};