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 16 struct 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 25 static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map) 26 { 27 return container_of(map, struct bpf_queue_stack, map); 28 } 29 30 static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs) 31 { 32 return qs->head == qs->tail; 33 } 34 35 static 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 */ 46 static 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 64 static 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 */ 87 static 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 94 static 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 } 121 122 out: 123 raw_spin_unlock_irqrestore(&qs->lock, flags); 124 return err; 125 } 126 127 128 static 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; 158 159 out: 160 raw_spin_unlock_irqrestore(&qs->lock, flags); 161 return err; 162 } 163 164 /* Called from syscall or from eBPF program */ 165 static 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 */ 171 static 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 */ 177 static 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 */ 183 static 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 */ 189 static 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; 228 229 out: 230 raw_spin_unlock_irqrestore(&qs->lock, irq_flags); 231 return err; 232 } 233 234 /* Called from syscall or from eBPF program */ 235 static 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 */ 241 static 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 */ 248 static long queue_stack_map_delete_elem(struct bpf_map *map, void *key) 249 { 250 return -EINVAL; 251 } 252 253 /* Called from syscall */ 254 static int queue_stack_map_get_next_key(struct bpf_map *map, void *key, 255 void *next_key) 256 { 257 return -EINVAL; 258 } 259 260 static 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 } 267 268 BTF_ID_LIST_SINGLE(queue_map_btf_ids, struct, bpf_queue_stack) 269 const 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 }; 284 285 const 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 }; 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