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 17 struct 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 26 static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map) 27 { 28 return container_of(map, struct bpf_queue_stack, map); 29 } 30 31 static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs) 32 { 33 return qs->head == qs->tail; 34 } 35 36 static 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 */ 47 static 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 68 static 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 memset(qs, 0, sizeof(*qs)); 82 83 bpf_map_init_from_attr(&qs->map, attr); 84 85 qs->size = size; 86 87 raw_spin_lock_init(&qs->lock); 88 89 return &qs->map; 90 } 91 92 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */ 93 static void queue_stack_map_free(struct bpf_map *map) 94 { 95 struct bpf_queue_stack *qs = bpf_queue_stack(map); 96 97 bpf_map_area_free(qs); 98 } 99 100 static int __queue_map_get(struct bpf_map *map, void *value, bool delete) 101 { 102 struct bpf_queue_stack *qs = bpf_queue_stack(map); 103 unsigned long flags; 104 int err = 0; 105 void *ptr; 106 107 raw_spin_lock_irqsave(&qs->lock, flags); 108 109 if (queue_stack_map_is_empty(qs)) { 110 memset(value, 0, qs->map.value_size); 111 err = -ENOENT; 112 goto out; 113 } 114 115 ptr = &qs->elements[qs->tail * qs->map.value_size]; 116 memcpy(value, ptr, qs->map.value_size); 117 118 if (delete) { 119 if (unlikely(++qs->tail >= qs->size)) 120 qs->tail = 0; 121 } 122 123 out: 124 raw_spin_unlock_irqrestore(&qs->lock, flags); 125 return err; 126 } 127 128 129 static int __stack_map_get(struct bpf_map *map, void *value, bool delete) 130 { 131 struct bpf_queue_stack *qs = bpf_queue_stack(map); 132 unsigned long flags; 133 int err = 0; 134 void *ptr; 135 u32 index; 136 137 raw_spin_lock_irqsave(&qs->lock, flags); 138 139 if (queue_stack_map_is_empty(qs)) { 140 memset(value, 0, qs->map.value_size); 141 err = -ENOENT; 142 goto out; 143 } 144 145 index = qs->head - 1; 146 if (unlikely(index >= qs->size)) 147 index = qs->size - 1; 148 149 ptr = &qs->elements[index * qs->map.value_size]; 150 memcpy(value, ptr, qs->map.value_size); 151 152 if (delete) 153 qs->head = index; 154 155 out: 156 raw_spin_unlock_irqrestore(&qs->lock, flags); 157 return err; 158 } 159 160 /* Called from syscall or from eBPF program */ 161 static int queue_map_peek_elem(struct bpf_map *map, void *value) 162 { 163 return __queue_map_get(map, value, false); 164 } 165 166 /* Called from syscall or from eBPF program */ 167 static int stack_map_peek_elem(struct bpf_map *map, void *value) 168 { 169 return __stack_map_get(map, value, false); 170 } 171 172 /* Called from syscall or from eBPF program */ 173 static int queue_map_pop_elem(struct bpf_map *map, void *value) 174 { 175 return __queue_map_get(map, value, true); 176 } 177 178 /* Called from syscall or from eBPF program */ 179 static int stack_map_pop_elem(struct bpf_map *map, void *value) 180 { 181 return __stack_map_get(map, value, true); 182 } 183 184 /* Called from syscall or from eBPF program */ 185 static int queue_stack_map_push_elem(struct bpf_map *map, void *value, 186 u64 flags) 187 { 188 struct bpf_queue_stack *qs = bpf_queue_stack(map); 189 unsigned long irq_flags; 190 int err = 0; 191 void *dst; 192 193 /* BPF_EXIST is used to force making room for a new element in case the 194 * map is full 195 */ 196 bool replace = (flags & BPF_EXIST); 197 198 /* Check supported flags for queue and stack maps */ 199 if (flags & BPF_NOEXIST || flags > BPF_EXIST) 200 return -EINVAL; 201 202 raw_spin_lock_irqsave(&qs->lock, irq_flags); 203 204 if (queue_stack_map_is_full(qs)) { 205 if (!replace) { 206 err = -E2BIG; 207 goto out; 208 } 209 /* advance tail pointer to overwrite oldest element */ 210 if (unlikely(++qs->tail >= qs->size)) 211 qs->tail = 0; 212 } 213 214 dst = &qs->elements[qs->head * qs->map.value_size]; 215 memcpy(dst, value, qs->map.value_size); 216 217 if (unlikely(++qs->head >= qs->size)) 218 qs->head = 0; 219 220 out: 221 raw_spin_unlock_irqrestore(&qs->lock, irq_flags); 222 return err; 223 } 224 225 /* Called from syscall or from eBPF program */ 226 static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key) 227 { 228 return NULL; 229 } 230 231 /* Called from syscall or from eBPF program */ 232 static int queue_stack_map_update_elem(struct bpf_map *map, void *key, 233 void *value, u64 flags) 234 { 235 return -EINVAL; 236 } 237 238 /* Called from syscall or from eBPF program */ 239 static int queue_stack_map_delete_elem(struct bpf_map *map, void *key) 240 { 241 return -EINVAL; 242 } 243 244 /* Called from syscall */ 245 static int queue_stack_map_get_next_key(struct bpf_map *map, void *key, 246 void *next_key) 247 { 248 return -EINVAL; 249 } 250 251 BTF_ID_LIST_SINGLE(queue_map_btf_ids, struct, bpf_queue_stack) 252 const struct bpf_map_ops queue_map_ops = { 253 .map_meta_equal = bpf_map_meta_equal, 254 .map_alloc_check = queue_stack_map_alloc_check, 255 .map_alloc = queue_stack_map_alloc, 256 .map_free = queue_stack_map_free, 257 .map_lookup_elem = queue_stack_map_lookup_elem, 258 .map_update_elem = queue_stack_map_update_elem, 259 .map_delete_elem = queue_stack_map_delete_elem, 260 .map_push_elem = queue_stack_map_push_elem, 261 .map_pop_elem = queue_map_pop_elem, 262 .map_peek_elem = queue_map_peek_elem, 263 .map_get_next_key = queue_stack_map_get_next_key, 264 .map_btf_id = &queue_map_btf_ids[0], 265 }; 266 267 const struct bpf_map_ops stack_map_ops = { 268 .map_meta_equal = bpf_map_meta_equal, 269 .map_alloc_check = queue_stack_map_alloc_check, 270 .map_alloc = queue_stack_map_alloc, 271 .map_free = queue_stack_map_free, 272 .map_lookup_elem = queue_stack_map_lookup_elem, 273 .map_update_elem = queue_stack_map_update_elem, 274 .map_delete_elem = queue_stack_map_delete_elem, 275 .map_push_elem = queue_stack_map_push_elem, 276 .map_pop_elem = stack_map_pop_elem, 277 .map_peek_elem = stack_map_peek_elem, 278 .map_get_next_key = queue_stack_map_get_next_key, 279 .map_btf_id = &queue_map_btf_ids[0], 280 }; 281