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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * queue_stack_maps.c: BPF queue and stack maps
4 *
5 * Copyright (c) 2018 Politecnico di Torino
6 */
7#include <linux/bpf.h>
8#include <linux/list.h>
9#include <linux/slab.h>
10#include <linux/capability.h>
11#include <linux/btf_ids.h>
12#include "percpu_freelist.h"
13
14#define QUEUE_STACK_CREATE_FLAG_MASK \
15 (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK)
16
17struct bpf_queue_stack {
18 struct bpf_map map;
19 raw_spinlock_t lock;
20 u32 head, tail;
21 u32 size; /* max_entries + 1 */
22
23 char elements[] __aligned(8);
24};
25
26static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map)
27{
28 return container_of(map, struct bpf_queue_stack, map);
29}
30
31static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs)
32{
33 return qs->head == qs->tail;
34}
35
36static bool queue_stack_map_is_full(struct bpf_queue_stack *qs)
37{
38 u32 head = qs->head + 1;
39
40 if (unlikely(head >= qs->size))
41 head = 0;
42
43 return head == qs->tail;
44}
45
46/* Called from syscall */
47static int queue_stack_map_alloc_check(union bpf_attr *attr)
48{
49 if (!bpf_capable())
50 return -EPERM;
51
52 /* check sanity of attributes */
53 if (attr->max_entries == 0 || attr->key_size != 0 ||
54 attr->value_size == 0 ||
55 attr->map_flags & ~QUEUE_STACK_CREATE_FLAG_MASK ||
56 !bpf_map_flags_access_ok(attr->map_flags))
57 return -EINVAL;
58
59 if (attr->value_size > KMALLOC_MAX_SIZE)
60 /* if value_size is bigger, the user space won't be able to
61 * access the elements.
62 */
63 return -E2BIG;
64
65 return 0;
66}
67
68static struct bpf_map *queue_stack_map_alloc(union bpf_attr *attr)
69{
70 int numa_node = bpf_map_attr_numa_node(attr);
71 struct bpf_queue_stack *qs;
72 u64 size, queue_size;
73
74 size = (u64) attr->max_entries + 1;
75 queue_size = sizeof(*qs) + size * attr->value_size;
76
77 qs = bpf_map_area_alloc(queue_size, numa_node);
78 if (!qs)
79 return ERR_PTR(-ENOMEM);
80
81 bpf_map_init_from_attr(&qs->map, attr);
82
83 qs->size = size;
84
85 raw_spin_lock_init(&qs->lock);
86
87 return &qs->map;
88}
89
90/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
91static void queue_stack_map_free(struct bpf_map *map)
92{
93 struct bpf_queue_stack *qs = bpf_queue_stack(map);
94
95 bpf_map_area_free(qs);
96}
97
98static int __queue_map_get(struct bpf_map *map, void *value, bool delete)
99{
100 struct bpf_queue_stack *qs = bpf_queue_stack(map);
101 unsigned long flags;
102 int err = 0;
103 void *ptr;
104
105 raw_spin_lock_irqsave(&qs->lock, flags);
106
107 if (queue_stack_map_is_empty(qs)) {
108 memset(value, 0, qs->map.value_size);
109 err = -ENOENT;
110 goto out;
111 }
112
113 ptr = &qs->elements[qs->tail * qs->map.value_size];
114 memcpy(value, ptr, qs->map.value_size);
115
116 if (delete) {
117 if (unlikely(++qs->tail >= qs->size))
118 qs->tail = 0;
119 }
120
121out:
122 raw_spin_unlock_irqrestore(&qs->lock, flags);
123 return err;
124}
125
126
127static int __stack_map_get(struct bpf_map *map, void *value, bool delete)
128{
129 struct bpf_queue_stack *qs = bpf_queue_stack(map);
130 unsigned long flags;
131 int err = 0;
132 void *ptr;
133 u32 index;
134
135 raw_spin_lock_irqsave(&qs->lock, flags);
136
137 if (queue_stack_map_is_empty(qs)) {
138 memset(value, 0, qs->map.value_size);
139 err = -ENOENT;
140 goto out;
141 }
142
143 index = qs->head - 1;
144 if (unlikely(index >= qs->size))
145 index = qs->size - 1;
146
147 ptr = &qs->elements[index * qs->map.value_size];
148 memcpy(value, ptr, qs->map.value_size);
149
150 if (delete)
151 qs->head = index;
152
153out:
154 raw_spin_unlock_irqrestore(&qs->lock, flags);
155 return err;
156}
157
158/* Called from syscall or from eBPF program */
159static int queue_map_peek_elem(struct bpf_map *map, void *value)
160{
161 return __queue_map_get(map, value, false);
162}
163
164/* Called from syscall or from eBPF program */
165static int stack_map_peek_elem(struct bpf_map *map, void *value)
166{
167 return __stack_map_get(map, value, false);
168}
169
170/* Called from syscall or from eBPF program */
171static int queue_map_pop_elem(struct bpf_map *map, void *value)
172{
173 return __queue_map_get(map, value, true);
174}
175
176/* Called from syscall or from eBPF program */
177static int stack_map_pop_elem(struct bpf_map *map, void *value)
178{
179 return __stack_map_get(map, value, true);
180}
181
182/* Called from syscall or from eBPF program */
183static int queue_stack_map_push_elem(struct bpf_map *map, void *value,
184 u64 flags)
185{
186 struct bpf_queue_stack *qs = bpf_queue_stack(map);
187 unsigned long irq_flags;
188 int err = 0;
189 void *dst;
190
191 /* BPF_EXIST is used to force making room for a new element in case the
192 * map is full
193 */
194 bool replace = (flags & BPF_EXIST);
195
196 /* Check supported flags for queue and stack maps */
197 if (flags & BPF_NOEXIST || flags > BPF_EXIST)
198 return -EINVAL;
199
200 raw_spin_lock_irqsave(&qs->lock, irq_flags);
201
202 if (queue_stack_map_is_full(qs)) {
203 if (!replace) {
204 err = -E2BIG;
205 goto out;
206 }
207 /* advance tail pointer to overwrite oldest element */
208 if (unlikely(++qs->tail >= qs->size))
209 qs->tail = 0;
210 }
211
212 dst = &qs->elements[qs->head * qs->map.value_size];
213 memcpy(dst, value, qs->map.value_size);
214
215 if (unlikely(++qs->head >= qs->size))
216 qs->head = 0;
217
218out:
219 raw_spin_unlock_irqrestore(&qs->lock, irq_flags);
220 return err;
221}
222
223/* Called from syscall or from eBPF program */
224static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key)
225{
226 return NULL;
227}
228
229/* Called from syscall or from eBPF program */
230static int queue_stack_map_update_elem(struct bpf_map *map, void *key,
231 void *value, u64 flags)
232{
233 return -EINVAL;
234}
235
236/* Called from syscall or from eBPF program */
237static int queue_stack_map_delete_elem(struct bpf_map *map, void *key)
238{
239 return -EINVAL;
240}
241
242/* Called from syscall */
243static int queue_stack_map_get_next_key(struct bpf_map *map, void *key,
244 void *next_key)
245{
246 return -EINVAL;
247}
248
249BTF_ID_LIST_SINGLE(queue_map_btf_ids, struct, bpf_queue_stack)
250const struct bpf_map_ops queue_map_ops = {
251 .map_meta_equal = bpf_map_meta_equal,
252 .map_alloc_check = queue_stack_map_alloc_check,
253 .map_alloc = queue_stack_map_alloc,
254 .map_free = queue_stack_map_free,
255 .map_lookup_elem = queue_stack_map_lookup_elem,
256 .map_update_elem = queue_stack_map_update_elem,
257 .map_delete_elem = queue_stack_map_delete_elem,
258 .map_push_elem = queue_stack_map_push_elem,
259 .map_pop_elem = queue_map_pop_elem,
260 .map_peek_elem = queue_map_peek_elem,
261 .map_get_next_key = queue_stack_map_get_next_key,
262 .map_btf_id = &queue_map_btf_ids[0],
263};
264
265const struct bpf_map_ops stack_map_ops = {
266 .map_meta_equal = bpf_map_meta_equal,
267 .map_alloc_check = queue_stack_map_alloc_check,
268 .map_alloc = queue_stack_map_alloc,
269 .map_free = queue_stack_map_free,
270 .map_lookup_elem = queue_stack_map_lookup_elem,
271 .map_update_elem = queue_stack_map_update_elem,
272 .map_delete_elem = queue_stack_map_delete_elem,
273 .map_push_elem = queue_stack_map_push_elem,
274 .map_pop_elem = stack_map_pop_elem,
275 .map_peek_elem = stack_map_peek_elem,
276 .map_get_next_key = queue_stack_map_get_next_key,
277 .map_btf_id = &queue_map_btf_ids[0],
278};
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * queue_stack_maps.c: BPF queue and stack maps
4 *
5 * Copyright (c) 2018 Politecnico di Torino
6 */
7#include <linux/bpf.h>
8#include <linux/list.h>
9#include <linux/slab.h>
10#include <linux/capability.h>
11#include "percpu_freelist.h"
12
13#define QUEUE_STACK_CREATE_FLAG_MASK \
14 (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK)
15
16struct bpf_queue_stack {
17 struct bpf_map map;
18 raw_spinlock_t lock;
19 u32 head, tail;
20 u32 size; /* max_entries + 1 */
21
22 char elements[0] __aligned(8);
23};
24
25static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map)
26{
27 return container_of(map, struct bpf_queue_stack, map);
28}
29
30static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs)
31{
32 return qs->head == qs->tail;
33}
34
35static bool queue_stack_map_is_full(struct bpf_queue_stack *qs)
36{
37 u32 head = qs->head + 1;
38
39 if (unlikely(head >= qs->size))
40 head = 0;
41
42 return head == qs->tail;
43}
44
45/* Called from syscall */
46static int queue_stack_map_alloc_check(union bpf_attr *attr)
47{
48 if (!capable(CAP_SYS_ADMIN))
49 return -EPERM;
50
51 /* check sanity of attributes */
52 if (attr->max_entries == 0 || attr->key_size != 0 ||
53 attr->value_size == 0 ||
54 attr->map_flags & ~QUEUE_STACK_CREATE_FLAG_MASK ||
55 !bpf_map_flags_access_ok(attr->map_flags))
56 return -EINVAL;
57
58 if (attr->value_size > KMALLOC_MAX_SIZE)
59 /* if value_size is bigger, the user space won't be able to
60 * access the elements.
61 */
62 return -E2BIG;
63
64 return 0;
65}
66
67static struct bpf_map *queue_stack_map_alloc(union bpf_attr *attr)
68{
69 int ret, numa_node = bpf_map_attr_numa_node(attr);
70 struct bpf_map_memory mem = {0};
71 struct bpf_queue_stack *qs;
72 u64 size, queue_size, cost;
73
74 size = (u64) attr->max_entries + 1;
75 cost = queue_size = sizeof(*qs) + size * attr->value_size;
76
77 ret = bpf_map_charge_init(&mem, cost);
78 if (ret < 0)
79 return ERR_PTR(ret);
80
81 qs = bpf_map_area_alloc(queue_size, numa_node);
82 if (!qs) {
83 bpf_map_charge_finish(&mem);
84 return ERR_PTR(-ENOMEM);
85 }
86
87 memset(qs, 0, sizeof(*qs));
88
89 bpf_map_init_from_attr(&qs->map, attr);
90
91 bpf_map_charge_move(&qs->map.memory, &mem);
92 qs->size = size;
93
94 raw_spin_lock_init(&qs->lock);
95
96 return &qs->map;
97}
98
99/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
100static void queue_stack_map_free(struct bpf_map *map)
101{
102 struct bpf_queue_stack *qs = bpf_queue_stack(map);
103
104 /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
105 * so the programs (can be more than one that used this map) were
106 * disconnected from events. Wait for outstanding critical sections in
107 * these programs to complete
108 */
109 synchronize_rcu();
110
111 bpf_map_area_free(qs);
112}
113
114static int __queue_map_get(struct bpf_map *map, void *value, bool delete)
115{
116 struct bpf_queue_stack *qs = bpf_queue_stack(map);
117 unsigned long flags;
118 int err = 0;
119 void *ptr;
120
121 raw_spin_lock_irqsave(&qs->lock, flags);
122
123 if (queue_stack_map_is_empty(qs)) {
124 memset(value, 0, qs->map.value_size);
125 err = -ENOENT;
126 goto out;
127 }
128
129 ptr = &qs->elements[qs->tail * qs->map.value_size];
130 memcpy(value, ptr, qs->map.value_size);
131
132 if (delete) {
133 if (unlikely(++qs->tail >= qs->size))
134 qs->tail = 0;
135 }
136
137out:
138 raw_spin_unlock_irqrestore(&qs->lock, flags);
139 return err;
140}
141
142
143static int __stack_map_get(struct bpf_map *map, void *value, bool delete)
144{
145 struct bpf_queue_stack *qs = bpf_queue_stack(map);
146 unsigned long flags;
147 int err = 0;
148 void *ptr;
149 u32 index;
150
151 raw_spin_lock_irqsave(&qs->lock, flags);
152
153 if (queue_stack_map_is_empty(qs)) {
154 memset(value, 0, qs->map.value_size);
155 err = -ENOENT;
156 goto out;
157 }
158
159 index = qs->head - 1;
160 if (unlikely(index >= qs->size))
161 index = qs->size - 1;
162
163 ptr = &qs->elements[index * qs->map.value_size];
164 memcpy(value, ptr, qs->map.value_size);
165
166 if (delete)
167 qs->head = index;
168
169out:
170 raw_spin_unlock_irqrestore(&qs->lock, flags);
171 return err;
172}
173
174/* Called from syscall or from eBPF program */
175static int queue_map_peek_elem(struct bpf_map *map, void *value)
176{
177 return __queue_map_get(map, value, false);
178}
179
180/* Called from syscall or from eBPF program */
181static int stack_map_peek_elem(struct bpf_map *map, void *value)
182{
183 return __stack_map_get(map, value, false);
184}
185
186/* Called from syscall or from eBPF program */
187static int queue_map_pop_elem(struct bpf_map *map, void *value)
188{
189 return __queue_map_get(map, value, true);
190}
191
192/* Called from syscall or from eBPF program */
193static int stack_map_pop_elem(struct bpf_map *map, void *value)
194{
195 return __stack_map_get(map, value, true);
196}
197
198/* Called from syscall or from eBPF program */
199static int queue_stack_map_push_elem(struct bpf_map *map, void *value,
200 u64 flags)
201{
202 struct bpf_queue_stack *qs = bpf_queue_stack(map);
203 unsigned long irq_flags;
204 int err = 0;
205 void *dst;
206
207 /* BPF_EXIST is used to force making room for a new element in case the
208 * map is full
209 */
210 bool replace = (flags & BPF_EXIST);
211
212 /* Check supported flags for queue and stack maps */
213 if (flags & BPF_NOEXIST || flags > BPF_EXIST)
214 return -EINVAL;
215
216 raw_spin_lock_irqsave(&qs->lock, irq_flags);
217
218 if (queue_stack_map_is_full(qs)) {
219 if (!replace) {
220 err = -E2BIG;
221 goto out;
222 }
223 /* advance tail pointer to overwrite oldest element */
224 if (unlikely(++qs->tail >= qs->size))
225 qs->tail = 0;
226 }
227
228 dst = &qs->elements[qs->head * qs->map.value_size];
229 memcpy(dst, value, qs->map.value_size);
230
231 if (unlikely(++qs->head >= qs->size))
232 qs->head = 0;
233
234out:
235 raw_spin_unlock_irqrestore(&qs->lock, irq_flags);
236 return err;
237}
238
239/* Called from syscall or from eBPF program */
240static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key)
241{
242 return NULL;
243}
244
245/* Called from syscall or from eBPF program */
246static int queue_stack_map_update_elem(struct bpf_map *map, void *key,
247 void *value, u64 flags)
248{
249 return -EINVAL;
250}
251
252/* Called from syscall or from eBPF program */
253static int queue_stack_map_delete_elem(struct bpf_map *map, void *key)
254{
255 return -EINVAL;
256}
257
258/* Called from syscall */
259static int queue_stack_map_get_next_key(struct bpf_map *map, void *key,
260 void *next_key)
261{
262 return -EINVAL;
263}
264
265const struct bpf_map_ops queue_map_ops = {
266 .map_alloc_check = queue_stack_map_alloc_check,
267 .map_alloc = queue_stack_map_alloc,
268 .map_free = queue_stack_map_free,
269 .map_lookup_elem = queue_stack_map_lookup_elem,
270 .map_update_elem = queue_stack_map_update_elem,
271 .map_delete_elem = queue_stack_map_delete_elem,
272 .map_push_elem = queue_stack_map_push_elem,
273 .map_pop_elem = queue_map_pop_elem,
274 .map_peek_elem = queue_map_peek_elem,
275 .map_get_next_key = queue_stack_map_get_next_key,
276};
277
278const struct bpf_map_ops stack_map_ops = {
279 .map_alloc_check = queue_stack_map_alloc_check,
280 .map_alloc = queue_stack_map_alloc,
281 .map_free = queue_stack_map_free,
282 .map_lookup_elem = queue_stack_map_lookup_elem,
283 .map_update_elem = queue_stack_map_update_elem,
284 .map_delete_elem = queue_stack_map_delete_elem,
285 .map_push_elem = queue_stack_map_push_elem,
286 .map_pop_elem = stack_map_pop_elem,
287 .map_peek_elem = stack_map_peek_elem,
288 .map_get_next_key = queue_stack_map_get_next_key,
289};