// SPDX-License-Identifier: GPL-2.0 /* * queue_stack_maps.c: BPF queue and stack maps * * Copyright (c) 2018 Politecnico di Torino */ #include <linux/bpf.h> #include <linux/list.h> #include <linux/slab.h> #include <linux/capability.h> #include <linux/btf_ids.h> #include "percpu_freelist.h" #define QUEUE_STACK_CREATE_FLAG_MASK \ (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK) struct bpf_queue_stack { struct bpf_map map; raw_spinlock_t lock; u32 head, tail; u32 size; /* max_entries + 1 */ char elements[] __aligned(8); }; static struct bpf_queue_stack *bpf_queue_stack(struct bpf_map *map) { return container_of(map, struct bpf_queue_stack, map); } static bool queue_stack_map_is_empty(struct bpf_queue_stack *qs) { return qs->head == qs->tail; } static bool queue_stack_map_is_full(struct bpf_queue_stack *qs) { u32 head = qs->head + 1; if (unlikely(head >= qs->size)) head = 0; return head == qs->tail; } /* Called from syscall */ static int queue_stack_map_alloc_check(union bpf_attr *attr) { if (!bpf_capable()) return -EPERM; /* check sanity of attributes */ if (attr->max_entries == 0 || attr->key_size != 0 || attr->value_size == 0 || attr->map_flags & ~QUEUE_STACK_CREATE_FLAG_MASK || !bpf_map_flags_access_ok(attr->map_flags)) return -EINVAL; if (attr->value_size > KMALLOC_MAX_SIZE) /* if value_size is bigger, the user space won't be able to * access the elements. */ return -E2BIG; return 0; } static struct bpf_map *queue_stack_map_alloc(union bpf_attr *attr) { int numa_node = bpf_map_attr_numa_node(attr); struct bpf_queue_stack *qs; u64 size, queue_size; size = (u64) attr->max_entries + 1; queue_size = sizeof(*qs) + size * attr->value_size; qs = bpf_map_area_alloc(queue_size, numa_node); if (!qs) return ERR_PTR(-ENOMEM); bpf_map_init_from_attr(&qs->map, attr); qs->size = size; raw_spin_lock_init(&qs->lock); return &qs->map; } /* Called when map->refcnt goes to zero, either from workqueue or from syscall */ static void queue_stack_map_free(struct bpf_map *map) { struct bpf_queue_stack *qs = bpf_queue_stack(map); bpf_map_area_free(qs); } static int __queue_map_get(struct bpf_map *map, void *value, bool delete) { struct bpf_queue_stack *qs = bpf_queue_stack(map); unsigned long flags; int err = 0; void *ptr; raw_spin_lock_irqsave(&qs->lock, flags); if (queue_stack_map_is_empty(qs)) { memset(value, 0, qs->map.value_size); err = -ENOENT; goto out; } ptr = &qs->elements[qs->tail * qs->map.value_size]; memcpy(value, ptr, qs->map.value_size); if (delete) { if (unlikely(++qs->tail >= qs->size)) qs->tail = 0; } out: raw_spin_unlock_irqrestore(&qs->lock, flags); return err; } static int __stack_map_get(struct bpf_map *map, void *value, bool delete) { struct bpf_queue_stack *qs = bpf_queue_stack(map); unsigned long flags; int err = 0; void *ptr; u32 index; raw_spin_lock_irqsave(&qs->lock, flags); if (queue_stack_map_is_empty(qs)) { memset(value, 0, qs->map.value_size); err = -ENOENT; goto out; } index = qs->head - 1; if (unlikely(index >= qs->size)) index = qs->size - 1; ptr = &qs->elements[index * qs->map.value_size]; memcpy(value, ptr, qs->map.value_size); if (delete) qs->head = index; out: raw_spin_unlock_irqrestore(&qs->lock, flags); return err; } /* Called from syscall or from eBPF program */ static int queue_map_peek_elem(struct bpf_map *map, void *value) { return __queue_map_get(map, value, false); } /* Called from syscall or from eBPF program */ static int stack_map_peek_elem(struct bpf_map *map, void *value) { return __stack_map_get(map, value, false); } /* Called from syscall or from eBPF program */ static int queue_map_pop_elem(struct bpf_map *map, void *value) { return __queue_map_get(map, value, true); } /* Called from syscall or from eBPF program */ static int stack_map_pop_elem(struct bpf_map *map, void *value) { return __stack_map_get(map, value, true); } /* Called from syscall or from eBPF program */ static int queue_stack_map_push_elem(struct bpf_map *map, void *value, u64 flags) { struct bpf_queue_stack *qs = bpf_queue_stack(map); unsigned long irq_flags; int err = 0; void *dst; /* BPF_EXIST is used to force making room for a new element in case the * map is full */ bool replace = (flags & BPF_EXIST); /* Check supported flags for queue and stack maps */ if (flags & BPF_NOEXIST || flags > BPF_EXIST) return -EINVAL; raw_spin_lock_irqsave(&qs->lock, irq_flags); if (queue_stack_map_is_full(qs)) { if (!replace) { err = -E2BIG; goto out; } /* advance tail pointer to overwrite oldest element */ if (unlikely(++qs->tail >= qs->size)) qs->tail = 0; } dst = &qs->elements[qs->head * qs->map.value_size]; memcpy(dst, value, qs->map.value_size); if (unlikely(++qs->head >= qs->size)) qs->head = 0; out: raw_spin_unlock_irqrestore(&qs->lock, irq_flags); return err; } /* Called from syscall or from eBPF program */ static void *queue_stack_map_lookup_elem(struct bpf_map *map, void *key) { return NULL; } /* Called from syscall or from eBPF program */ static int queue_stack_map_update_elem(struct bpf_map *map, void *key, void *value, u64 flags) { return -EINVAL; } /* Called from syscall or from eBPF program */ static int queue_stack_map_delete_elem(struct bpf_map *map, void *key) { return -EINVAL; } /* Called from syscall */ static int queue_stack_map_get_next_key(struct bpf_map *map, void *key, void *next_key) { return -EINVAL; } BTF_ID_LIST_SINGLE(queue_map_btf_ids, struct, bpf_queue_stack) const struct bpf_map_ops queue_map_ops = { .map_meta_equal = bpf_map_meta_equal, .map_alloc_check = queue_stack_map_alloc_check, .map_alloc = queue_stack_map_alloc, .map_free = queue_stack_map_free, .map_lookup_elem = queue_stack_map_lookup_elem, .map_update_elem = queue_stack_map_update_elem, .map_delete_elem = queue_stack_map_delete_elem, .map_push_elem = queue_stack_map_push_elem, .map_pop_elem = queue_map_pop_elem, .map_peek_elem = queue_map_peek_elem, .map_get_next_key = queue_stack_map_get_next_key, .map_btf_id = &queue_map_btf_ids[0], }; const struct bpf_map_ops stack_map_ops = { .map_meta_equal = bpf_map_meta_equal, .map_alloc_check = queue_stack_map_alloc_check, .map_alloc = queue_stack_map_alloc, .map_free = queue_stack_map_free, .map_lookup_elem = queue_stack_map_lookup_elem, .map_update_elem = queue_stack_map_update_elem, .map_delete_elem = queue_stack_map_delete_elem, .map_push_elem = queue_stack_map_push_elem, .map_pop_elem = stack_map_pop_elem, .map_peek_elem = stack_map_peek_elem, .map_get_next_key = queue_stack_map_get_next_key, .map_btf_id = &queue_map_btf_ids[0], };