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 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 if (!bpf_capable()) 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 67 static 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 */ 100 static void queue_stack_map_free(struct bpf_map *map) 101 { 102 struct bpf_queue_stack *qs = bpf_queue_stack(map); 103 104 bpf_map_area_free(qs); 105 } 106 107 static int __queue_map_get(struct bpf_map *map, void *value, bool delete) 108 { 109 struct bpf_queue_stack *qs = bpf_queue_stack(map); 110 unsigned long flags; 111 int err = 0; 112 void *ptr; 113 114 raw_spin_lock_irqsave(&qs->lock, flags); 115 116 if (queue_stack_map_is_empty(qs)) { 117 memset(value, 0, qs->map.value_size); 118 err = -ENOENT; 119 goto out; 120 } 121 122 ptr = &qs->elements[qs->tail * qs->map.value_size]; 123 memcpy(value, ptr, qs->map.value_size); 124 125 if (delete) { 126 if (unlikely(++qs->tail >= qs->size)) 127 qs->tail = 0; 128 } 129 130 out: 131 raw_spin_unlock_irqrestore(&qs->lock, flags); 132 return err; 133 } 134 135 136 static int __stack_map_get(struct bpf_map *map, void *value, bool delete) 137 { 138 struct bpf_queue_stack *qs = bpf_queue_stack(map); 139 unsigned long flags; 140 int err = 0; 141 void *ptr; 142 u32 index; 143 144 raw_spin_lock_irqsave(&qs->lock, flags); 145 146 if (queue_stack_map_is_empty(qs)) { 147 memset(value, 0, qs->map.value_size); 148 err = -ENOENT; 149 goto out; 150 } 151 152 index = qs->head - 1; 153 if (unlikely(index >= qs->size)) 154 index = qs->size - 1; 155 156 ptr = &qs->elements[index * qs->map.value_size]; 157 memcpy(value, ptr, qs->map.value_size); 158 159 if (delete) 160 qs->head = index; 161 162 out: 163 raw_spin_unlock_irqrestore(&qs->lock, flags); 164 return err; 165 } 166 167 /* Called from syscall or from eBPF program */ 168 static int queue_map_peek_elem(struct bpf_map *map, void *value) 169 { 170 return __queue_map_get(map, value, false); 171 } 172 173 /* Called from syscall or from eBPF program */ 174 static int stack_map_peek_elem(struct bpf_map *map, void *value) 175 { 176 return __stack_map_get(map, value, false); 177 } 178 179 /* Called from syscall or from eBPF program */ 180 static int queue_map_pop_elem(struct bpf_map *map, void *value) 181 { 182 return __queue_map_get(map, value, true); 183 } 184 185 /* Called from syscall or from eBPF program */ 186 static int stack_map_pop_elem(struct bpf_map *map, void *value) 187 { 188 return __stack_map_get(map, value, true); 189 } 190 191 /* Called from syscall or from eBPF program */ 192 static int queue_stack_map_push_elem(struct bpf_map *map, void *value, 193 u64 flags) 194 { 195 struct bpf_queue_stack *qs = bpf_queue_stack(map); 196 unsigned long irq_flags; 197 int err = 0; 198 void *dst; 199 200 /* BPF_EXIST is used to force making room for a new element in case the 201 * map is full 202 */ 203 bool replace = (flags & BPF_EXIST); 204 205 /* Check supported flags for queue and stack maps */ 206 if (flags & BPF_NOEXIST || flags > BPF_EXIST) 207 return -EINVAL; 208 209 raw_spin_lock_irqsave(&qs->lock, irq_flags); 210 211 if (queue_stack_map_is_full(qs)) { 212 if (!replace) { 213 err = -E2BIG; 214 goto out; 215 } 216 /* advance tail pointer to overwrite oldest element */ 217 if (unlikely(++qs->tail >= qs->size)) 218 qs->tail = 0; 219 } 220 221 dst = &qs->elements[qs->head * qs->map.value_size]; 222 memcpy(dst, value, qs->map.value_size); 223 224 if (unlikely(++qs->head >= qs->size)) 225 qs->head = 0; 226 227 out: 228 raw_spin_unlock_irqrestore(&qs->lock, irq_flags); 229 return err; 230 } 231 232 /* Called from syscall or from eBPF program */ 233 static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key) 234 { 235 return NULL; 236 } 237 238 /* Called from syscall or from eBPF program */ 239 static int queue_stack_map_update_elem(struct bpf_map *map, void *key, 240 void *value, u64 flags) 241 { 242 return -EINVAL; 243 } 244 245 /* Called from syscall or from eBPF program */ 246 static int queue_stack_map_delete_elem(struct bpf_map *map, void *key) 247 { 248 return -EINVAL; 249 } 250 251 /* Called from syscall */ 252 static int queue_stack_map_get_next_key(struct bpf_map *map, void *key, 253 void *next_key) 254 { 255 return -EINVAL; 256 } 257 258 static int queue_map_btf_id; 259 const struct bpf_map_ops queue_map_ops = { 260 .map_alloc_check = queue_stack_map_alloc_check, 261 .map_alloc = queue_stack_map_alloc, 262 .map_free = queue_stack_map_free, 263 .map_lookup_elem = queue_stack_map_lookup_elem, 264 .map_update_elem = queue_stack_map_update_elem, 265 .map_delete_elem = queue_stack_map_delete_elem, 266 .map_push_elem = queue_stack_map_push_elem, 267 .map_pop_elem = queue_map_pop_elem, 268 .map_peek_elem = queue_map_peek_elem, 269 .map_get_next_key = queue_stack_map_get_next_key, 270 .map_btf_name = "bpf_queue_stack", 271 .map_btf_id = &queue_map_btf_id, 272 }; 273 274 static int stack_map_btf_id; 275 const struct bpf_map_ops stack_map_ops = { 276 .map_alloc_check = queue_stack_map_alloc_check, 277 .map_alloc = queue_stack_map_alloc, 278 .map_free = queue_stack_map_free, 279 .map_lookup_elem = queue_stack_map_lookup_elem, 280 .map_update_elem = queue_stack_map_update_elem, 281 .map_delete_elem = queue_stack_map_delete_elem, 282 .map_push_elem = queue_stack_map_push_elem, 283 .map_pop_elem = stack_map_pop_elem, 284 .map_peek_elem = stack_map_peek_elem, 285 .map_get_next_key = queue_stack_map_get_next_key, 286 .map_btf_name = "bpf_queue_stack", 287 .map_btf_id = &stack_map_btf_id, 288 }; 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