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 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 */ 91 static 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 98 static 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 } 120 121 out: 122 raw_spin_unlock_irqrestore(&qs->lock, flags); 123 return err; 124 } 125 126 127 static 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; 152 153 out: 154 raw_spin_unlock_irqrestore(&qs->lock, flags); 155 return err; 156 } 157 158 /* Called from syscall or from eBPF program */ 159 static 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 */ 165 static 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 */ 171 static 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 */ 177 static 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 */ 183 static 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; 217 218 out: 219 raw_spin_unlock_irqrestore(&qs->lock, irq_flags); 220 return err; 221 } 222 223 /* Called from syscall or from eBPF program */ 224 static 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 */ 230 static 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 */ 237 static int queue_stack_map_delete_elem(struct bpf_map *map, void *key) 238 { 239 return -EINVAL; 240 } 241 242 /* Called from syscall */ 243 static int queue_stack_map_get_next_key(struct bpf_map *map, void *key, 244 void *next_key) 245 { 246 return -EINVAL; 247 } 248 249 BTF_ID_LIST_SINGLE(queue_map_btf_ids, struct, bpf_queue_stack) 250 const 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 }; 264 265 const 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 }; 279