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 numa_node = bpf_map_attr_numa_node(attr); 70 struct bpf_queue_stack *qs; 71 u64 size, queue_size; 72 73 size = (u64) attr->max_entries + 1; 74 queue_size = sizeof(*qs) + size * attr->value_size; 75 76 qs = bpf_map_area_alloc(queue_size, numa_node); 77 if (!qs) 78 return ERR_PTR(-ENOMEM); 79 80 memset(qs, 0, sizeof(*qs)); 81 82 bpf_map_init_from_attr(&qs->map, attr); 83 84 qs->size = size; 85 86 raw_spin_lock_init(&qs->lock); 87 88 return &qs->map; 89 } 90 91 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */ 92 static void queue_stack_map_free(struct bpf_map *map) 93 { 94 struct bpf_queue_stack *qs = bpf_queue_stack(map); 95 96 bpf_map_area_free(qs); 97 } 98 99 static int __queue_map_get(struct bpf_map *map, void *value, bool delete) 100 { 101 struct bpf_queue_stack *qs = bpf_queue_stack(map); 102 unsigned long flags; 103 int err = 0; 104 void *ptr; 105 106 raw_spin_lock_irqsave(&qs->lock, flags); 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 int __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 raw_spin_lock_irqsave(&qs->lock, flags); 137 138 if (queue_stack_map_is_empty(qs)) { 139 memset(value, 0, qs->map.value_size); 140 err = -ENOENT; 141 goto out; 142 } 143 144 index = qs->head - 1; 145 if (unlikely(index >= qs->size)) 146 index = qs->size - 1; 147 148 ptr = &qs->elements[index * qs->map.value_size]; 149 memcpy(value, ptr, qs->map.value_size); 150 151 if (delete) 152 qs->head = index; 153 154 out: 155 raw_spin_unlock_irqrestore(&qs->lock, flags); 156 return err; 157 } 158 159 /* Called from syscall or from eBPF program */ 160 static int queue_map_peek_elem(struct bpf_map *map, void *value) 161 { 162 return __queue_map_get(map, value, false); 163 } 164 165 /* Called from syscall or from eBPF program */ 166 static int stack_map_peek_elem(struct bpf_map *map, void *value) 167 { 168 return __stack_map_get(map, value, false); 169 } 170 171 /* Called from syscall or from eBPF program */ 172 static int queue_map_pop_elem(struct bpf_map *map, void *value) 173 { 174 return __queue_map_get(map, value, true); 175 } 176 177 /* Called from syscall or from eBPF program */ 178 static int stack_map_pop_elem(struct bpf_map *map, void *value) 179 { 180 return __stack_map_get(map, value, true); 181 } 182 183 /* Called from syscall or from eBPF program */ 184 static int queue_stack_map_push_elem(struct bpf_map *map, void *value, 185 u64 flags) 186 { 187 struct bpf_queue_stack *qs = bpf_queue_stack(map); 188 unsigned long irq_flags; 189 int err = 0; 190 void *dst; 191 192 /* BPF_EXIST is used to force making room for a new element in case the 193 * map is full 194 */ 195 bool replace = (flags & BPF_EXIST); 196 197 /* Check supported flags for queue and stack maps */ 198 if (flags & BPF_NOEXIST || flags > BPF_EXIST) 199 return -EINVAL; 200 201 raw_spin_lock_irqsave(&qs->lock, irq_flags); 202 203 if (queue_stack_map_is_full(qs)) { 204 if (!replace) { 205 err = -E2BIG; 206 goto out; 207 } 208 /* advance tail pointer to overwrite oldest element */ 209 if (unlikely(++qs->tail >= qs->size)) 210 qs->tail = 0; 211 } 212 213 dst = &qs->elements[qs->head * qs->map.value_size]; 214 memcpy(dst, value, qs->map.value_size); 215 216 if (unlikely(++qs->head >= qs->size)) 217 qs->head = 0; 218 219 out: 220 raw_spin_unlock_irqrestore(&qs->lock, irq_flags); 221 return err; 222 } 223 224 /* Called from syscall or from eBPF program */ 225 static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key) 226 { 227 return NULL; 228 } 229 230 /* Called from syscall or from eBPF program */ 231 static int queue_stack_map_update_elem(struct bpf_map *map, void *key, 232 void *value, u64 flags) 233 { 234 return -EINVAL; 235 } 236 237 /* Called from syscall or from eBPF program */ 238 static int queue_stack_map_delete_elem(struct bpf_map *map, void *key) 239 { 240 return -EINVAL; 241 } 242 243 /* Called from syscall */ 244 static int queue_stack_map_get_next_key(struct bpf_map *map, void *key, 245 void *next_key) 246 { 247 return -EINVAL; 248 } 249 250 static int queue_map_btf_id; 251 const struct bpf_map_ops queue_map_ops = { 252 .map_meta_equal = bpf_map_meta_equal, 253 .map_alloc_check = queue_stack_map_alloc_check, 254 .map_alloc = queue_stack_map_alloc, 255 .map_free = queue_stack_map_free, 256 .map_lookup_elem = queue_stack_map_lookup_elem, 257 .map_update_elem = queue_stack_map_update_elem, 258 .map_delete_elem = queue_stack_map_delete_elem, 259 .map_push_elem = queue_stack_map_push_elem, 260 .map_pop_elem = queue_map_pop_elem, 261 .map_peek_elem = queue_map_peek_elem, 262 .map_get_next_key = queue_stack_map_get_next_key, 263 .map_btf_name = "bpf_queue_stack", 264 .map_btf_id = &queue_map_btf_id, 265 }; 266 267 static int stack_map_btf_id; 268 const struct bpf_map_ops stack_map_ops = { 269 .map_meta_equal = bpf_map_meta_equal, 270 .map_alloc_check = queue_stack_map_alloc_check, 271 .map_alloc = queue_stack_map_alloc, 272 .map_free = queue_stack_map_free, 273 .map_lookup_elem = queue_stack_map_lookup_elem, 274 .map_update_elem = queue_stack_map_update_elem, 275 .map_delete_elem = queue_stack_map_delete_elem, 276 .map_push_elem = queue_stack_map_push_elem, 277 .map_pop_elem = stack_map_pop_elem, 278 .map_peek_elem = stack_map_peek_elem, 279 .map_get_next_key = queue_stack_map_get_next_key, 280 .map_btf_name = "bpf_queue_stack", 281 .map_btf_id = &stack_map_btf_id, 282 }; 283