Loading...
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/btf_ids.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[] __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 /* check sanity of attributes */
49 if (attr->max_entries == 0 || attr->key_size != 0 ||
50 attr->value_size == 0 ||
51 attr->map_flags & ~QUEUE_STACK_CREATE_FLAG_MASK ||
52 !bpf_map_flags_access_ok(attr->map_flags))
53 return -EINVAL;
54
55 if (attr->value_size > KMALLOC_MAX_SIZE)
56 /* if value_size is bigger, the user space won't be able to
57 * access the elements.
58 */
59 return -E2BIG;
60
61 return 0;
62}
63
64static struct bpf_map *queue_stack_map_alloc(union bpf_attr *attr)
65{
66 int numa_node = bpf_map_attr_numa_node(attr);
67 struct bpf_queue_stack *qs;
68 u64 size, queue_size;
69
70 size = (u64) attr->max_entries + 1;
71 queue_size = sizeof(*qs) + size * attr->value_size;
72
73 qs = bpf_map_area_alloc(queue_size, numa_node);
74 if (!qs)
75 return ERR_PTR(-ENOMEM);
76
77 bpf_map_init_from_attr(&qs->map, attr);
78
79 qs->size = size;
80
81 raw_spin_lock_init(&qs->lock);
82
83 return &qs->map;
84}
85
86/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
87static void queue_stack_map_free(struct bpf_map *map)
88{
89 struct bpf_queue_stack *qs = bpf_queue_stack(map);
90
91 bpf_map_area_free(qs);
92}
93
94static long __queue_map_get(struct bpf_map *map, void *value, bool delete)
95{
96 struct bpf_queue_stack *qs = bpf_queue_stack(map);
97 unsigned long flags;
98 int err = 0;
99 void *ptr;
100
101 if (in_nmi()) {
102 if (!raw_spin_trylock_irqsave(&qs->lock, flags))
103 return -EBUSY;
104 } else {
105 raw_spin_lock_irqsave(&qs->lock, flags);
106 }
107
108 if (queue_stack_map_is_empty(qs)) {
109 memset(value, 0, qs->map.value_size);
110 err = -ENOENT;
111 goto out;
112 }
113
114 ptr = &qs->elements[qs->tail * qs->map.value_size];
115 memcpy(value, ptr, qs->map.value_size);
116
117 if (delete) {
118 if (unlikely(++qs->tail >= qs->size))
119 qs->tail = 0;
120 }
121
122out:
123 raw_spin_unlock_irqrestore(&qs->lock, flags);
124 return err;
125}
126
127
128static long __stack_map_get(struct bpf_map *map, void *value, bool delete)
129{
130 struct bpf_queue_stack *qs = bpf_queue_stack(map);
131 unsigned long flags;
132 int err = 0;
133 void *ptr;
134 u32 index;
135
136 if (in_nmi()) {
137 if (!raw_spin_trylock_irqsave(&qs->lock, flags))
138 return -EBUSY;
139 } else {
140 raw_spin_lock_irqsave(&qs->lock, flags);
141 }
142
143 if (queue_stack_map_is_empty(qs)) {
144 memset(value, 0, qs->map.value_size);
145 err = -ENOENT;
146 goto out;
147 }
148
149 index = qs->head - 1;
150 if (unlikely(index >= qs->size))
151 index = qs->size - 1;
152
153 ptr = &qs->elements[index * qs->map.value_size];
154 memcpy(value, ptr, qs->map.value_size);
155
156 if (delete)
157 qs->head = index;
158
159out:
160 raw_spin_unlock_irqrestore(&qs->lock, flags);
161 return err;
162}
163
164/* Called from syscall or from eBPF program */
165static long queue_map_peek_elem(struct bpf_map *map, void *value)
166{
167 return __queue_map_get(map, value, false);
168}
169
170/* Called from syscall or from eBPF program */
171static long stack_map_peek_elem(struct bpf_map *map, void *value)
172{
173 return __stack_map_get(map, value, false);
174}
175
176/* Called from syscall or from eBPF program */
177static long queue_map_pop_elem(struct bpf_map *map, void *value)
178{
179 return __queue_map_get(map, value, true);
180}
181
182/* Called from syscall or from eBPF program */
183static long stack_map_pop_elem(struct bpf_map *map, void *value)
184{
185 return __stack_map_get(map, value, true);
186}
187
188/* Called from syscall or from eBPF program */
189static long queue_stack_map_push_elem(struct bpf_map *map, void *value,
190 u64 flags)
191{
192 struct bpf_queue_stack *qs = bpf_queue_stack(map);
193 unsigned long irq_flags;
194 int err = 0;
195 void *dst;
196
197 /* BPF_EXIST is used to force making room for a new element in case the
198 * map is full
199 */
200 bool replace = (flags & BPF_EXIST);
201
202 /* Check supported flags for queue and stack maps */
203 if (flags & BPF_NOEXIST || flags > BPF_EXIST)
204 return -EINVAL;
205
206 if (in_nmi()) {
207 if (!raw_spin_trylock_irqsave(&qs->lock, irq_flags))
208 return -EBUSY;
209 } else {
210 raw_spin_lock_irqsave(&qs->lock, irq_flags);
211 }
212
213 if (queue_stack_map_is_full(qs)) {
214 if (!replace) {
215 err = -E2BIG;
216 goto out;
217 }
218 /* advance tail pointer to overwrite oldest element */
219 if (unlikely(++qs->tail >= qs->size))
220 qs->tail = 0;
221 }
222
223 dst = &qs->elements[qs->head * qs->map.value_size];
224 memcpy(dst, value, qs->map.value_size);
225
226 if (unlikely(++qs->head >= qs->size))
227 qs->head = 0;
228
229out:
230 raw_spin_unlock_irqrestore(&qs->lock, irq_flags);
231 return err;
232}
233
234/* Called from syscall or from eBPF program */
235static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key)
236{
237 return NULL;
238}
239
240/* Called from syscall or from eBPF program */
241static long queue_stack_map_update_elem(struct bpf_map *map, void *key,
242 void *value, u64 flags)
243{
244 return -EINVAL;
245}
246
247/* Called from syscall or from eBPF program */
248static long queue_stack_map_delete_elem(struct bpf_map *map, void *key)
249{
250 return -EINVAL;
251}
252
253/* Called from syscall */
254static int queue_stack_map_get_next_key(struct bpf_map *map, void *key,
255 void *next_key)
256{
257 return -EINVAL;
258}
259
260static u64 queue_stack_map_mem_usage(const struct bpf_map *map)
261{
262 u64 usage = sizeof(struct bpf_queue_stack);
263
264 usage += ((u64)map->max_entries + 1) * map->value_size;
265 return usage;
266}
267
268BTF_ID_LIST_SINGLE(queue_map_btf_ids, struct, bpf_queue_stack)
269const struct bpf_map_ops queue_map_ops = {
270 .map_meta_equal = bpf_map_meta_equal,
271 .map_alloc_check = queue_stack_map_alloc_check,
272 .map_alloc = queue_stack_map_alloc,
273 .map_free = queue_stack_map_free,
274 .map_lookup_elem = queue_stack_map_lookup_elem,
275 .map_update_elem = queue_stack_map_update_elem,
276 .map_delete_elem = queue_stack_map_delete_elem,
277 .map_push_elem = queue_stack_map_push_elem,
278 .map_pop_elem = queue_map_pop_elem,
279 .map_peek_elem = queue_map_peek_elem,
280 .map_get_next_key = queue_stack_map_get_next_key,
281 .map_mem_usage = queue_stack_map_mem_usage,
282 .map_btf_id = &queue_map_btf_ids[0],
283};
284
285const struct bpf_map_ops stack_map_ops = {
286 .map_meta_equal = bpf_map_meta_equal,
287 .map_alloc_check = queue_stack_map_alloc_check,
288 .map_alloc = queue_stack_map_alloc,
289 .map_free = queue_stack_map_free,
290 .map_lookup_elem = queue_stack_map_lookup_elem,
291 .map_update_elem = queue_stack_map_update_elem,
292 .map_delete_elem = queue_stack_map_delete_elem,
293 .map_push_elem = queue_stack_map_push_elem,
294 .map_pop_elem = stack_map_pop_elem,
295 .map_peek_elem = stack_map_peek_elem,
296 .map_get_next_key = queue_stack_map_get_next_key,
297 .map_mem_usage = queue_stack_map_mem_usage,
298 .map_btf_id = &queue_map_btf_ids[0],
299};
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};