forked from Minki/linux
4fe8435909
when all map elements are pre-allocated one cpu can delete and reuse htab_elem
while another cpu is still walking the hlist. In such case the lookup may
miss the element. Convert hlist to hlist_nulls to avoid such scenario.
When bucket lock is taken there is no need to take such precautions,
so only convert map_lookup and map_get_next to nulls.
The race window is extremely small and only reproducible with explicit
udelay() inside lookup_nulls_elem_raw()
Similar to hlist add hlist_nulls_for_each_entry_safe() and
hlist_nulls_entry_safe() helpers.
Fixes: 6c90598174
("bpf: pre-allocate hash map elements")
Reported-by: Jonathan Perry <jonperry@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
1196 lines
30 KiB
C
1196 lines
30 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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* Copyright (c) 2016 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/bpf.h>
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#include <linux/jhash.h>
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#include <linux/filter.h>
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#include <linux/rculist_nulls.h>
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#include "percpu_freelist.h"
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#include "bpf_lru_list.h"
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struct bucket {
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struct hlist_nulls_head head;
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raw_spinlock_t lock;
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};
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struct bpf_htab {
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struct bpf_map map;
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struct bucket *buckets;
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void *elems;
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union {
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struct pcpu_freelist freelist;
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struct bpf_lru lru;
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};
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void __percpu *extra_elems;
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atomic_t count; /* number of elements in this hashtable */
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u32 n_buckets; /* number of hash buckets */
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u32 elem_size; /* size of each element in bytes */
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};
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enum extra_elem_state {
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HTAB_NOT_AN_EXTRA_ELEM = 0,
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HTAB_EXTRA_ELEM_FREE,
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HTAB_EXTRA_ELEM_USED
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};
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/* each htab element is struct htab_elem + key + value */
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struct htab_elem {
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union {
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struct hlist_nulls_node hash_node;
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struct {
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void *padding;
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union {
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struct bpf_htab *htab;
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struct pcpu_freelist_node fnode;
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};
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};
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};
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union {
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struct rcu_head rcu;
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enum extra_elem_state state;
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struct bpf_lru_node lru_node;
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};
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u32 hash;
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char key[0] __aligned(8);
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};
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static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node);
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static bool htab_is_lru(const struct bpf_htab *htab)
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{
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return htab->map.map_type == BPF_MAP_TYPE_LRU_HASH ||
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htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
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}
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static bool htab_is_percpu(const struct bpf_htab *htab)
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{
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return htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH ||
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htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
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}
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static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size,
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void __percpu *pptr)
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{
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*(void __percpu **)(l->key + key_size) = pptr;
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}
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static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size)
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{
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return *(void __percpu **)(l->key + key_size);
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}
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static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i)
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{
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return (struct htab_elem *) (htab->elems + i * htab->elem_size);
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}
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static void htab_free_elems(struct bpf_htab *htab)
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{
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int i;
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if (!htab_is_percpu(htab))
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goto free_elems;
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for (i = 0; i < htab->map.max_entries; i++) {
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void __percpu *pptr;
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pptr = htab_elem_get_ptr(get_htab_elem(htab, i),
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htab->map.key_size);
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free_percpu(pptr);
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}
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free_elems:
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bpf_map_area_free(htab->elems);
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}
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static struct htab_elem *prealloc_lru_pop(struct bpf_htab *htab, void *key,
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u32 hash)
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{
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struct bpf_lru_node *node = bpf_lru_pop_free(&htab->lru, hash);
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struct htab_elem *l;
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if (node) {
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l = container_of(node, struct htab_elem, lru_node);
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memcpy(l->key, key, htab->map.key_size);
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return l;
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}
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return NULL;
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}
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static int prealloc_init(struct bpf_htab *htab)
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{
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int err = -ENOMEM, i;
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htab->elems = bpf_map_area_alloc(htab->elem_size *
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htab->map.max_entries);
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if (!htab->elems)
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return -ENOMEM;
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if (!htab_is_percpu(htab))
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goto skip_percpu_elems;
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for (i = 0; i < htab->map.max_entries; i++) {
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u32 size = round_up(htab->map.value_size, 8);
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void __percpu *pptr;
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pptr = __alloc_percpu_gfp(size, 8, GFP_USER | __GFP_NOWARN);
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if (!pptr)
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goto free_elems;
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htab_elem_set_ptr(get_htab_elem(htab, i), htab->map.key_size,
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pptr);
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}
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skip_percpu_elems:
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if (htab_is_lru(htab))
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err = bpf_lru_init(&htab->lru,
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htab->map.map_flags & BPF_F_NO_COMMON_LRU,
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offsetof(struct htab_elem, hash) -
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offsetof(struct htab_elem, lru_node),
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htab_lru_map_delete_node,
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htab);
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else
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err = pcpu_freelist_init(&htab->freelist);
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if (err)
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goto free_elems;
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if (htab_is_lru(htab))
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bpf_lru_populate(&htab->lru, htab->elems,
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offsetof(struct htab_elem, lru_node),
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htab->elem_size, htab->map.max_entries);
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else
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pcpu_freelist_populate(&htab->freelist,
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htab->elems + offsetof(struct htab_elem, fnode),
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htab->elem_size, htab->map.max_entries);
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return 0;
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free_elems:
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htab_free_elems(htab);
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return err;
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}
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static void prealloc_destroy(struct bpf_htab *htab)
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{
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htab_free_elems(htab);
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if (htab_is_lru(htab))
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bpf_lru_destroy(&htab->lru);
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else
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pcpu_freelist_destroy(&htab->freelist);
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}
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static int alloc_extra_elems(struct bpf_htab *htab)
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{
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void __percpu *pptr;
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int cpu;
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pptr = __alloc_percpu_gfp(htab->elem_size, 8, GFP_USER | __GFP_NOWARN);
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if (!pptr)
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return -ENOMEM;
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for_each_possible_cpu(cpu) {
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((struct htab_elem *)per_cpu_ptr(pptr, cpu))->state =
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HTAB_EXTRA_ELEM_FREE;
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}
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htab->extra_elems = pptr;
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return 0;
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}
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/* Called from syscall */
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static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
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{
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bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
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attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
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bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
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attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
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/* percpu_lru means each cpu has its own LRU list.
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* it is different from BPF_MAP_TYPE_PERCPU_HASH where
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* the map's value itself is percpu. percpu_lru has
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* nothing to do with the map's value.
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*/
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bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
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bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
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struct bpf_htab *htab;
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int err, i;
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u64 cost;
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BUILD_BUG_ON(offsetof(struct htab_elem, htab) !=
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offsetof(struct htab_elem, hash_node.pprev));
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BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) !=
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offsetof(struct htab_elem, hash_node.pprev));
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if (lru && !capable(CAP_SYS_ADMIN))
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/* LRU implementation is much complicated than other
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* maps. Hence, limit to CAP_SYS_ADMIN for now.
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*/
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return ERR_PTR(-EPERM);
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if (attr->map_flags & ~(BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU))
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/* reserved bits should not be used */
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return ERR_PTR(-EINVAL);
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if (!lru && percpu_lru)
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return ERR_PTR(-EINVAL);
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if (lru && !prealloc)
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return ERR_PTR(-ENOTSUPP);
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htab = kzalloc(sizeof(*htab), GFP_USER);
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if (!htab)
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return ERR_PTR(-ENOMEM);
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/* mandatory map attributes */
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htab->map.map_type = attr->map_type;
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htab->map.key_size = attr->key_size;
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htab->map.value_size = attr->value_size;
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htab->map.max_entries = attr->max_entries;
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htab->map.map_flags = attr->map_flags;
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/* check sanity of attributes.
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* value_size == 0 may be allowed in the future to use map as a set
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*/
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err = -EINVAL;
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if (htab->map.max_entries == 0 || htab->map.key_size == 0 ||
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htab->map.value_size == 0)
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goto free_htab;
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if (percpu_lru) {
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/* ensure each CPU's lru list has >=1 elements.
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* since we are at it, make each lru list has the same
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* number of elements.
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*/
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htab->map.max_entries = roundup(attr->max_entries,
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num_possible_cpus());
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if (htab->map.max_entries < attr->max_entries)
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htab->map.max_entries = rounddown(attr->max_entries,
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num_possible_cpus());
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}
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/* hash table size must be power of 2 */
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htab->n_buckets = roundup_pow_of_two(htab->map.max_entries);
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err = -E2BIG;
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if (htab->map.key_size > MAX_BPF_STACK)
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/* eBPF programs initialize keys on stack, so they cannot be
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* larger than max stack size
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*/
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goto free_htab;
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if (htab->map.value_size >= KMALLOC_MAX_SIZE -
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MAX_BPF_STACK - sizeof(struct htab_elem))
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/* if value_size is bigger, the user space won't be able to
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* access the elements via bpf syscall. This check also makes
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* sure that the elem_size doesn't overflow and it's
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* kmalloc-able later in htab_map_update_elem()
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*/
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goto free_htab;
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if (percpu && round_up(htab->map.value_size, 8) > PCPU_MIN_UNIT_SIZE)
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/* make sure the size for pcpu_alloc() is reasonable */
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goto free_htab;
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htab->elem_size = sizeof(struct htab_elem) +
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round_up(htab->map.key_size, 8);
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if (percpu)
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htab->elem_size += sizeof(void *);
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else
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htab->elem_size += round_up(htab->map.value_size, 8);
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|
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/* prevent zero size kmalloc and check for u32 overflow */
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if (htab->n_buckets == 0 ||
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htab->n_buckets > U32_MAX / sizeof(struct bucket))
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goto free_htab;
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cost = (u64) htab->n_buckets * sizeof(struct bucket) +
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(u64) htab->elem_size * htab->map.max_entries;
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if (percpu)
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cost += (u64) round_up(htab->map.value_size, 8) *
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num_possible_cpus() * htab->map.max_entries;
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else
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cost += (u64) htab->elem_size * num_possible_cpus();
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if (cost >= U32_MAX - PAGE_SIZE)
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/* make sure page count doesn't overflow */
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goto free_htab;
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|
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htab->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;
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|
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/* if map size is larger than memlock limit, reject it early */
|
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err = bpf_map_precharge_memlock(htab->map.pages);
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if (err)
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goto free_htab;
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err = -ENOMEM;
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htab->buckets = bpf_map_area_alloc(htab->n_buckets *
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sizeof(struct bucket));
|
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if (!htab->buckets)
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goto free_htab;
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|
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for (i = 0; i < htab->n_buckets; i++) {
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INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i);
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raw_spin_lock_init(&htab->buckets[i].lock);
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}
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|
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if (!percpu && !lru) {
|
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/* lru itself can remove the least used element, so
|
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* there is no need for an extra elem during map_update.
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*/
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err = alloc_extra_elems(htab);
|
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if (err)
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goto free_buckets;
|
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}
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|
|
if (prealloc) {
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err = prealloc_init(htab);
|
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if (err)
|
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goto free_extra_elems;
|
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}
|
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|
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return &htab->map;
|
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|
|
free_extra_elems:
|
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free_percpu(htab->extra_elems);
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free_buckets:
|
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bpf_map_area_free(htab->buckets);
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free_htab:
|
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kfree(htab);
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return ERR_PTR(err);
|
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}
|
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|
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static inline u32 htab_map_hash(const void *key, u32 key_len)
|
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{
|
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return jhash(key, key_len, 0);
|
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}
|
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|
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static inline struct bucket *__select_bucket(struct bpf_htab *htab, u32 hash)
|
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{
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return &htab->buckets[hash & (htab->n_buckets - 1)];
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}
|
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|
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static inline struct hlist_nulls_head *select_bucket(struct bpf_htab *htab, u32 hash)
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{
|
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return &__select_bucket(htab, hash)->head;
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}
|
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|
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/* this lookup function can only be called with bucket lock taken */
|
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static struct htab_elem *lookup_elem_raw(struct hlist_nulls_head *head, u32 hash,
|
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void *key, u32 key_size)
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{
|
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struct hlist_nulls_node *n;
|
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struct htab_elem *l;
|
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|
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hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
|
|
if (l->hash == hash && !memcmp(&l->key, key, key_size))
|
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return l;
|
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|
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return NULL;
|
|
}
|
|
|
|
/* can be called without bucket lock. it will repeat the loop in
|
|
* the unlikely event when elements moved from one bucket into another
|
|
* while link list is being walked
|
|
*/
|
|
static struct htab_elem *lookup_nulls_elem_raw(struct hlist_nulls_head *head,
|
|
u32 hash, void *key,
|
|
u32 key_size, u32 n_buckets)
|
|
{
|
|
struct hlist_nulls_node *n;
|
|
struct htab_elem *l;
|
|
|
|
again:
|
|
hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
|
|
if (l->hash == hash && !memcmp(&l->key, key, key_size))
|
|
return l;
|
|
|
|
if (unlikely(get_nulls_value(n) != (hash & (n_buckets - 1))))
|
|
goto again;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/* Called from syscall or from eBPF program */
|
|
static void *__htab_map_lookup_elem(struct bpf_map *map, void *key)
|
|
{
|
|
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
|
|
struct hlist_nulls_head *head;
|
|
struct htab_elem *l;
|
|
u32 hash, key_size;
|
|
|
|
/* Must be called with rcu_read_lock. */
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
key_size = map->key_size;
|
|
|
|
hash = htab_map_hash(key, key_size);
|
|
|
|
head = select_bucket(htab, hash);
|
|
|
|
l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
|
|
|
|
return l;
|
|
}
|
|
|
|
static void *htab_map_lookup_elem(struct bpf_map *map, void *key)
|
|
{
|
|
struct htab_elem *l = __htab_map_lookup_elem(map, key);
|
|
|
|
if (l)
|
|
return l->key + round_up(map->key_size, 8);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void *htab_lru_map_lookup_elem(struct bpf_map *map, void *key)
|
|
{
|
|
struct htab_elem *l = __htab_map_lookup_elem(map, key);
|
|
|
|
if (l) {
|
|
bpf_lru_node_set_ref(&l->lru_node);
|
|
return l->key + round_up(map->key_size, 8);
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/* It is called from the bpf_lru_list when the LRU needs to delete
|
|
* older elements from the htab.
|
|
*/
|
|
static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node)
|
|
{
|
|
struct bpf_htab *htab = (struct bpf_htab *)arg;
|
|
struct htab_elem *l = NULL, *tgt_l;
|
|
struct hlist_nulls_head *head;
|
|
struct hlist_nulls_node *n;
|
|
unsigned long flags;
|
|
struct bucket *b;
|
|
|
|
tgt_l = container_of(node, struct htab_elem, lru_node);
|
|
b = __select_bucket(htab, tgt_l->hash);
|
|
head = &b->head;
|
|
|
|
raw_spin_lock_irqsave(&b->lock, flags);
|
|
|
|
hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
|
|
if (l == tgt_l) {
|
|
hlist_nulls_del_rcu(&l->hash_node);
|
|
break;
|
|
}
|
|
|
|
raw_spin_unlock_irqrestore(&b->lock, flags);
|
|
|
|
return l == tgt_l;
|
|
}
|
|
|
|
/* Called from syscall */
|
|
static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
|
|
{
|
|
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
|
|
struct hlist_nulls_head *head;
|
|
struct htab_elem *l, *next_l;
|
|
u32 hash, key_size;
|
|
int i;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
key_size = map->key_size;
|
|
|
|
hash = htab_map_hash(key, key_size);
|
|
|
|
head = select_bucket(htab, hash);
|
|
|
|
/* lookup the key */
|
|
l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
|
|
|
|
if (!l) {
|
|
i = 0;
|
|
goto find_first_elem;
|
|
}
|
|
|
|
/* key was found, get next key in the same bucket */
|
|
next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_next_rcu(&l->hash_node)),
|
|
struct htab_elem, hash_node);
|
|
|
|
if (next_l) {
|
|
/* if next elem in this hash list is non-zero, just return it */
|
|
memcpy(next_key, next_l->key, key_size);
|
|
return 0;
|
|
}
|
|
|
|
/* no more elements in this hash list, go to the next bucket */
|
|
i = hash & (htab->n_buckets - 1);
|
|
i++;
|
|
|
|
find_first_elem:
|
|
/* iterate over buckets */
|
|
for (; i < htab->n_buckets; i++) {
|
|
head = select_bucket(htab, i);
|
|
|
|
/* pick first element in the bucket */
|
|
next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_first_rcu(head)),
|
|
struct htab_elem, hash_node);
|
|
if (next_l) {
|
|
/* if it's not empty, just return it */
|
|
memcpy(next_key, next_l->key, key_size);
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/* iterated over all buckets and all elements */
|
|
return -ENOENT;
|
|
}
|
|
|
|
static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
|
|
{
|
|
if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
|
|
free_percpu(htab_elem_get_ptr(l, htab->map.key_size));
|
|
kfree(l);
|
|
}
|
|
|
|
static void htab_elem_free_rcu(struct rcu_head *head)
|
|
{
|
|
struct htab_elem *l = container_of(head, struct htab_elem, rcu);
|
|
struct bpf_htab *htab = l->htab;
|
|
|
|
/* must increment bpf_prog_active to avoid kprobe+bpf triggering while
|
|
* we're calling kfree, otherwise deadlock is possible if kprobes
|
|
* are placed somewhere inside of slub
|
|
*/
|
|
preempt_disable();
|
|
__this_cpu_inc(bpf_prog_active);
|
|
htab_elem_free(htab, l);
|
|
__this_cpu_dec(bpf_prog_active);
|
|
preempt_enable();
|
|
}
|
|
|
|
static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
|
|
{
|
|
if (l->state == HTAB_EXTRA_ELEM_USED) {
|
|
l->state = HTAB_EXTRA_ELEM_FREE;
|
|
return;
|
|
}
|
|
|
|
if (!(htab->map.map_flags & BPF_F_NO_PREALLOC)) {
|
|
pcpu_freelist_push(&htab->freelist, &l->fnode);
|
|
} else {
|
|
atomic_dec(&htab->count);
|
|
l->htab = htab;
|
|
call_rcu(&l->rcu, htab_elem_free_rcu);
|
|
}
|
|
}
|
|
|
|
static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr,
|
|
void *value, bool onallcpus)
|
|
{
|
|
if (!onallcpus) {
|
|
/* copy true value_size bytes */
|
|
memcpy(this_cpu_ptr(pptr), value, htab->map.value_size);
|
|
} else {
|
|
u32 size = round_up(htab->map.value_size, 8);
|
|
int off = 0, cpu;
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
bpf_long_memcpy(per_cpu_ptr(pptr, cpu),
|
|
value + off, size);
|
|
off += size;
|
|
}
|
|
}
|
|
}
|
|
|
|
static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
|
|
void *value, u32 key_size, u32 hash,
|
|
bool percpu, bool onallcpus,
|
|
bool old_elem_exists)
|
|
{
|
|
u32 size = htab->map.value_size;
|
|
bool prealloc = !(htab->map.map_flags & BPF_F_NO_PREALLOC);
|
|
struct htab_elem *l_new;
|
|
void __percpu *pptr;
|
|
int err = 0;
|
|
|
|
if (prealloc) {
|
|
struct pcpu_freelist_node *l;
|
|
|
|
l = pcpu_freelist_pop(&htab->freelist);
|
|
if (!l)
|
|
err = -E2BIG;
|
|
else
|
|
l_new = container_of(l, struct htab_elem, fnode);
|
|
} else {
|
|
if (atomic_inc_return(&htab->count) > htab->map.max_entries) {
|
|
atomic_dec(&htab->count);
|
|
err = -E2BIG;
|
|
} else {
|
|
l_new = kmalloc(htab->elem_size,
|
|
GFP_ATOMIC | __GFP_NOWARN);
|
|
if (!l_new)
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
}
|
|
|
|
if (err) {
|
|
if (!old_elem_exists)
|
|
return ERR_PTR(err);
|
|
|
|
/* if we're updating the existing element and the hash table
|
|
* is full, use per-cpu extra elems
|
|
*/
|
|
l_new = this_cpu_ptr(htab->extra_elems);
|
|
if (l_new->state != HTAB_EXTRA_ELEM_FREE)
|
|
return ERR_PTR(-E2BIG);
|
|
l_new->state = HTAB_EXTRA_ELEM_USED;
|
|
} else {
|
|
l_new->state = HTAB_NOT_AN_EXTRA_ELEM;
|
|
}
|
|
|
|
memcpy(l_new->key, key, key_size);
|
|
if (percpu) {
|
|
/* round up value_size to 8 bytes */
|
|
size = round_up(size, 8);
|
|
|
|
if (prealloc) {
|
|
pptr = htab_elem_get_ptr(l_new, key_size);
|
|
} else {
|
|
/* alloc_percpu zero-fills */
|
|
pptr = __alloc_percpu_gfp(size, 8,
|
|
GFP_ATOMIC | __GFP_NOWARN);
|
|
if (!pptr) {
|
|
kfree(l_new);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
}
|
|
|
|
pcpu_copy_value(htab, pptr, value, onallcpus);
|
|
|
|
if (!prealloc)
|
|
htab_elem_set_ptr(l_new, key_size, pptr);
|
|
} else {
|
|
memcpy(l_new->key + round_up(key_size, 8), value, size);
|
|
}
|
|
|
|
l_new->hash = hash;
|
|
return l_new;
|
|
}
|
|
|
|
static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,
|
|
u64 map_flags)
|
|
{
|
|
if (l_old && map_flags == BPF_NOEXIST)
|
|
/* elem already exists */
|
|
return -EEXIST;
|
|
|
|
if (!l_old && map_flags == BPF_EXIST)
|
|
/* elem doesn't exist, cannot update it */
|
|
return -ENOENT;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Called from syscall or from eBPF program */
|
|
static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
|
|
u64 map_flags)
|
|
{
|
|
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
|
|
struct htab_elem *l_new = NULL, *l_old;
|
|
struct hlist_nulls_head *head;
|
|
unsigned long flags;
|
|
struct bucket *b;
|
|
u32 key_size, hash;
|
|
int ret;
|
|
|
|
if (unlikely(map_flags > BPF_EXIST))
|
|
/* unknown flags */
|
|
return -EINVAL;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
key_size = map->key_size;
|
|
|
|
hash = htab_map_hash(key, key_size);
|
|
|
|
b = __select_bucket(htab, hash);
|
|
head = &b->head;
|
|
|
|
/* bpf_map_update_elem() can be called in_irq() */
|
|
raw_spin_lock_irqsave(&b->lock, flags);
|
|
|
|
l_old = lookup_elem_raw(head, hash, key, key_size);
|
|
|
|
ret = check_flags(htab, l_old, map_flags);
|
|
if (ret)
|
|
goto err;
|
|
|
|
l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false,
|
|
!!l_old);
|
|
if (IS_ERR(l_new)) {
|
|
/* all pre-allocated elements are in use or memory exhausted */
|
|
ret = PTR_ERR(l_new);
|
|
goto err;
|
|
}
|
|
|
|
/* add new element to the head of the list, so that
|
|
* concurrent search will find it before old elem
|
|
*/
|
|
hlist_nulls_add_head_rcu(&l_new->hash_node, head);
|
|
if (l_old) {
|
|
hlist_nulls_del_rcu(&l_old->hash_node);
|
|
free_htab_elem(htab, l_old);
|
|
}
|
|
ret = 0;
|
|
err:
|
|
raw_spin_unlock_irqrestore(&b->lock, flags);
|
|
return ret;
|
|
}
|
|
|
|
static int htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value,
|
|
u64 map_flags)
|
|
{
|
|
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
|
|
struct htab_elem *l_new, *l_old = NULL;
|
|
struct hlist_nulls_head *head;
|
|
unsigned long flags;
|
|
struct bucket *b;
|
|
u32 key_size, hash;
|
|
int ret;
|
|
|
|
if (unlikely(map_flags > BPF_EXIST))
|
|
/* unknown flags */
|
|
return -EINVAL;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
key_size = map->key_size;
|
|
|
|
hash = htab_map_hash(key, key_size);
|
|
|
|
b = __select_bucket(htab, hash);
|
|
head = &b->head;
|
|
|
|
/* For LRU, we need to alloc before taking bucket's
|
|
* spinlock because getting free nodes from LRU may need
|
|
* to remove older elements from htab and this removal
|
|
* operation will need a bucket lock.
|
|
*/
|
|
l_new = prealloc_lru_pop(htab, key, hash);
|
|
if (!l_new)
|
|
return -ENOMEM;
|
|
memcpy(l_new->key + round_up(map->key_size, 8), value, map->value_size);
|
|
|
|
/* bpf_map_update_elem() can be called in_irq() */
|
|
raw_spin_lock_irqsave(&b->lock, flags);
|
|
|
|
l_old = lookup_elem_raw(head, hash, key, key_size);
|
|
|
|
ret = check_flags(htab, l_old, map_flags);
|
|
if (ret)
|
|
goto err;
|
|
|
|
/* add new element to the head of the list, so that
|
|
* concurrent search will find it before old elem
|
|
*/
|
|
hlist_nulls_add_head_rcu(&l_new->hash_node, head);
|
|
if (l_old) {
|
|
bpf_lru_node_set_ref(&l_new->lru_node);
|
|
hlist_nulls_del_rcu(&l_old->hash_node);
|
|
}
|
|
ret = 0;
|
|
|
|
err:
|
|
raw_spin_unlock_irqrestore(&b->lock, flags);
|
|
|
|
if (ret)
|
|
bpf_lru_push_free(&htab->lru, &l_new->lru_node);
|
|
else if (l_old)
|
|
bpf_lru_push_free(&htab->lru, &l_old->lru_node);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
|
|
void *value, u64 map_flags,
|
|
bool onallcpus)
|
|
{
|
|
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
|
|
struct htab_elem *l_new = NULL, *l_old;
|
|
struct hlist_nulls_head *head;
|
|
unsigned long flags;
|
|
struct bucket *b;
|
|
u32 key_size, hash;
|
|
int ret;
|
|
|
|
if (unlikely(map_flags > BPF_EXIST))
|
|
/* unknown flags */
|
|
return -EINVAL;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
key_size = map->key_size;
|
|
|
|
hash = htab_map_hash(key, key_size);
|
|
|
|
b = __select_bucket(htab, hash);
|
|
head = &b->head;
|
|
|
|
/* bpf_map_update_elem() can be called in_irq() */
|
|
raw_spin_lock_irqsave(&b->lock, flags);
|
|
|
|
l_old = lookup_elem_raw(head, hash, key, key_size);
|
|
|
|
ret = check_flags(htab, l_old, map_flags);
|
|
if (ret)
|
|
goto err;
|
|
|
|
if (l_old) {
|
|
/* per-cpu hash map can update value in-place */
|
|
pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
|
|
value, onallcpus);
|
|
} else {
|
|
l_new = alloc_htab_elem(htab, key, value, key_size,
|
|
hash, true, onallcpus, false);
|
|
if (IS_ERR(l_new)) {
|
|
ret = PTR_ERR(l_new);
|
|
goto err;
|
|
}
|
|
hlist_nulls_add_head_rcu(&l_new->hash_node, head);
|
|
}
|
|
ret = 0;
|
|
err:
|
|
raw_spin_unlock_irqrestore(&b->lock, flags);
|
|
return ret;
|
|
}
|
|
|
|
static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
|
|
void *value, u64 map_flags,
|
|
bool onallcpus)
|
|
{
|
|
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
|
|
struct htab_elem *l_new = NULL, *l_old;
|
|
struct hlist_nulls_head *head;
|
|
unsigned long flags;
|
|
struct bucket *b;
|
|
u32 key_size, hash;
|
|
int ret;
|
|
|
|
if (unlikely(map_flags > BPF_EXIST))
|
|
/* unknown flags */
|
|
return -EINVAL;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
key_size = map->key_size;
|
|
|
|
hash = htab_map_hash(key, key_size);
|
|
|
|
b = __select_bucket(htab, hash);
|
|
head = &b->head;
|
|
|
|
/* For LRU, we need to alloc before taking bucket's
|
|
* spinlock because LRU's elem alloc may need
|
|
* to remove older elem from htab and this removal
|
|
* operation will need a bucket lock.
|
|
*/
|
|
if (map_flags != BPF_EXIST) {
|
|
l_new = prealloc_lru_pop(htab, key, hash);
|
|
if (!l_new)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* bpf_map_update_elem() can be called in_irq() */
|
|
raw_spin_lock_irqsave(&b->lock, flags);
|
|
|
|
l_old = lookup_elem_raw(head, hash, key, key_size);
|
|
|
|
ret = check_flags(htab, l_old, map_flags);
|
|
if (ret)
|
|
goto err;
|
|
|
|
if (l_old) {
|
|
bpf_lru_node_set_ref(&l_old->lru_node);
|
|
|
|
/* per-cpu hash map can update value in-place */
|
|
pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
|
|
value, onallcpus);
|
|
} else {
|
|
pcpu_copy_value(htab, htab_elem_get_ptr(l_new, key_size),
|
|
value, onallcpus);
|
|
hlist_nulls_add_head_rcu(&l_new->hash_node, head);
|
|
l_new = NULL;
|
|
}
|
|
ret = 0;
|
|
err:
|
|
raw_spin_unlock_irqrestore(&b->lock, flags);
|
|
if (l_new)
|
|
bpf_lru_push_free(&htab->lru, &l_new->lru_node);
|
|
return ret;
|
|
}
|
|
|
|
static int htab_percpu_map_update_elem(struct bpf_map *map, void *key,
|
|
void *value, u64 map_flags)
|
|
{
|
|
return __htab_percpu_map_update_elem(map, key, value, map_flags, false);
|
|
}
|
|
|
|
static int htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
|
|
void *value, u64 map_flags)
|
|
{
|
|
return __htab_lru_percpu_map_update_elem(map, key, value, map_flags,
|
|
false);
|
|
}
|
|
|
|
/* Called from syscall or from eBPF program */
|
|
static int htab_map_delete_elem(struct bpf_map *map, void *key)
|
|
{
|
|
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
|
|
struct hlist_nulls_head *head;
|
|
struct bucket *b;
|
|
struct htab_elem *l;
|
|
unsigned long flags;
|
|
u32 hash, key_size;
|
|
int ret = -ENOENT;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
key_size = map->key_size;
|
|
|
|
hash = htab_map_hash(key, key_size);
|
|
b = __select_bucket(htab, hash);
|
|
head = &b->head;
|
|
|
|
raw_spin_lock_irqsave(&b->lock, flags);
|
|
|
|
l = lookup_elem_raw(head, hash, key, key_size);
|
|
|
|
if (l) {
|
|
hlist_nulls_del_rcu(&l->hash_node);
|
|
free_htab_elem(htab, l);
|
|
ret = 0;
|
|
}
|
|
|
|
raw_spin_unlock_irqrestore(&b->lock, flags);
|
|
return ret;
|
|
}
|
|
|
|
static int htab_lru_map_delete_elem(struct bpf_map *map, void *key)
|
|
{
|
|
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
|
|
struct hlist_nulls_head *head;
|
|
struct bucket *b;
|
|
struct htab_elem *l;
|
|
unsigned long flags;
|
|
u32 hash, key_size;
|
|
int ret = -ENOENT;
|
|
|
|
WARN_ON_ONCE(!rcu_read_lock_held());
|
|
|
|
key_size = map->key_size;
|
|
|
|
hash = htab_map_hash(key, key_size);
|
|
b = __select_bucket(htab, hash);
|
|
head = &b->head;
|
|
|
|
raw_spin_lock_irqsave(&b->lock, flags);
|
|
|
|
l = lookup_elem_raw(head, hash, key, key_size);
|
|
|
|
if (l) {
|
|
hlist_nulls_del_rcu(&l->hash_node);
|
|
ret = 0;
|
|
}
|
|
|
|
raw_spin_unlock_irqrestore(&b->lock, flags);
|
|
if (l)
|
|
bpf_lru_push_free(&htab->lru, &l->lru_node);
|
|
return ret;
|
|
}
|
|
|
|
static void delete_all_elements(struct bpf_htab *htab)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < htab->n_buckets; i++) {
|
|
struct hlist_nulls_head *head = select_bucket(htab, i);
|
|
struct hlist_nulls_node *n;
|
|
struct htab_elem *l;
|
|
|
|
hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
|
|
hlist_nulls_del_rcu(&l->hash_node);
|
|
if (l->state != HTAB_EXTRA_ELEM_USED)
|
|
htab_elem_free(htab, l);
|
|
}
|
|
}
|
|
}
|
|
/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
|
|
static void htab_map_free(struct bpf_map *map)
|
|
{
|
|
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
|
|
|
|
/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
|
|
* so the programs (can be more than one that used this map) were
|
|
* disconnected from events. Wait for outstanding critical sections in
|
|
* these programs to complete
|
|
*/
|
|
synchronize_rcu();
|
|
|
|
/* some of free_htab_elem() callbacks for elements of this map may
|
|
* not have executed. Wait for them.
|
|
*/
|
|
rcu_barrier();
|
|
if (htab->map.map_flags & BPF_F_NO_PREALLOC)
|
|
delete_all_elements(htab);
|
|
else
|
|
prealloc_destroy(htab);
|
|
|
|
free_percpu(htab->extra_elems);
|
|
bpf_map_area_free(htab->buckets);
|
|
kfree(htab);
|
|
}
|
|
|
|
static const struct bpf_map_ops htab_ops = {
|
|
.map_alloc = htab_map_alloc,
|
|
.map_free = htab_map_free,
|
|
.map_get_next_key = htab_map_get_next_key,
|
|
.map_lookup_elem = htab_map_lookup_elem,
|
|
.map_update_elem = htab_map_update_elem,
|
|
.map_delete_elem = htab_map_delete_elem,
|
|
};
|
|
|
|
static struct bpf_map_type_list htab_type __ro_after_init = {
|
|
.ops = &htab_ops,
|
|
.type = BPF_MAP_TYPE_HASH,
|
|
};
|
|
|
|
static const struct bpf_map_ops htab_lru_ops = {
|
|
.map_alloc = htab_map_alloc,
|
|
.map_free = htab_map_free,
|
|
.map_get_next_key = htab_map_get_next_key,
|
|
.map_lookup_elem = htab_lru_map_lookup_elem,
|
|
.map_update_elem = htab_lru_map_update_elem,
|
|
.map_delete_elem = htab_lru_map_delete_elem,
|
|
};
|
|
|
|
static struct bpf_map_type_list htab_lru_type __ro_after_init = {
|
|
.ops = &htab_lru_ops,
|
|
.type = BPF_MAP_TYPE_LRU_HASH,
|
|
};
|
|
|
|
/* Called from eBPF program */
|
|
static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key)
|
|
{
|
|
struct htab_elem *l = __htab_map_lookup_elem(map, key);
|
|
|
|
if (l)
|
|
return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
|
|
else
|
|
return NULL;
|
|
}
|
|
|
|
static void *htab_lru_percpu_map_lookup_elem(struct bpf_map *map, void *key)
|
|
{
|
|
struct htab_elem *l = __htab_map_lookup_elem(map, key);
|
|
|
|
if (l) {
|
|
bpf_lru_node_set_ref(&l->lru_node);
|
|
return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value)
|
|
{
|
|
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
|
|
struct htab_elem *l;
|
|
void __percpu *pptr;
|
|
int ret = -ENOENT;
|
|
int cpu, off = 0;
|
|
u32 size;
|
|
|
|
/* per_cpu areas are zero-filled and bpf programs can only
|
|
* access 'value_size' of them, so copying rounded areas
|
|
* will not leak any kernel data
|
|
*/
|
|
size = round_up(map->value_size, 8);
|
|
rcu_read_lock();
|
|
l = __htab_map_lookup_elem(map, key);
|
|
if (!l)
|
|
goto out;
|
|
if (htab_is_lru(htab))
|
|
bpf_lru_node_set_ref(&l->lru_node);
|
|
pptr = htab_elem_get_ptr(l, map->key_size);
|
|
for_each_possible_cpu(cpu) {
|
|
bpf_long_memcpy(value + off,
|
|
per_cpu_ptr(pptr, cpu), size);
|
|
off += size;
|
|
}
|
|
ret = 0;
|
|
out:
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
|
|
int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
|
|
u64 map_flags)
|
|
{
|
|
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
|
|
int ret;
|
|
|
|
rcu_read_lock();
|
|
if (htab_is_lru(htab))
|
|
ret = __htab_lru_percpu_map_update_elem(map, key, value,
|
|
map_flags, true);
|
|
else
|
|
ret = __htab_percpu_map_update_elem(map, key, value, map_flags,
|
|
true);
|
|
rcu_read_unlock();
|
|
|
|
return ret;
|
|
}
|
|
|
|
static const struct bpf_map_ops htab_percpu_ops = {
|
|
.map_alloc = htab_map_alloc,
|
|
.map_free = htab_map_free,
|
|
.map_get_next_key = htab_map_get_next_key,
|
|
.map_lookup_elem = htab_percpu_map_lookup_elem,
|
|
.map_update_elem = htab_percpu_map_update_elem,
|
|
.map_delete_elem = htab_map_delete_elem,
|
|
};
|
|
|
|
static struct bpf_map_type_list htab_percpu_type __ro_after_init = {
|
|
.ops = &htab_percpu_ops,
|
|
.type = BPF_MAP_TYPE_PERCPU_HASH,
|
|
};
|
|
|
|
static const struct bpf_map_ops htab_lru_percpu_ops = {
|
|
.map_alloc = htab_map_alloc,
|
|
.map_free = htab_map_free,
|
|
.map_get_next_key = htab_map_get_next_key,
|
|
.map_lookup_elem = htab_lru_percpu_map_lookup_elem,
|
|
.map_update_elem = htab_lru_percpu_map_update_elem,
|
|
.map_delete_elem = htab_lru_map_delete_elem,
|
|
};
|
|
|
|
static struct bpf_map_type_list htab_lru_percpu_type __ro_after_init = {
|
|
.ops = &htab_lru_percpu_ops,
|
|
.type = BPF_MAP_TYPE_LRU_PERCPU_HASH,
|
|
};
|
|
|
|
static int __init register_htab_map(void)
|
|
{
|
|
bpf_register_map_type(&htab_type);
|
|
bpf_register_map_type(&htab_percpu_type);
|
|
bpf_register_map_type(&htab_lru_type);
|
|
bpf_register_map_type(&htab_lru_percpu_type);
|
|
return 0;
|
|
}
|
|
late_initcall(register_htab_map);
|