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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Daniel Borkmann](/assets/img/avatar_default.png)
Commita6ed3ea65d
("bpf: restore behavior of bpf_map_update_elem") added an extra per-cpu reserve to the hash table map to restore old behaviour from pre prealloc times. When non-prealloc is in use for a map, then problem is that once a hash table extra element has been linked into the hash-table, and the hash table is destroyed due to refcount dropping to zero, then htab_map_free() -> delete_all_elements() will walk the whole hash table and drop all elements via htab_elem_free(). The problem is that the element from the extra reserve is first fed to the wrong backend allocator and eventually freed twice. Fixes:a6ed3ea65d
("bpf: restore behavior of bpf_map_update_elem") Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
808 lines
19 KiB
C
808 lines
19 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/vmalloc.h>
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#include "percpu_freelist.h"
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struct bucket {
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struct hlist_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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struct pcpu_freelist freelist;
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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_node hash_node;
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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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union {
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struct rcu_head rcu;
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enum extra_elem_state state;
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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 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->map.map_type != BPF_MAP_TYPE_PERCPU_HASH)
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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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vfree(htab->elems);
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}
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static int prealloc_elems_and_freelist(struct bpf_htab *htab)
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{
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int err = -ENOMEM, i;
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htab->elems = vzalloc(htab->elem_size * htab->map.max_entries);
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if (!htab->elems)
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return -ENOMEM;
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if (htab->map.map_type != BPF_MAP_TYPE_PERCPU_HASH)
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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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err = pcpu_freelist_init(&htab->freelist);
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if (err)
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goto free_elems;
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pcpu_freelist_populate(&htab->freelist, htab->elems, htab->elem_size,
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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 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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struct bpf_htab *htab;
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int err, i;
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u64 cost;
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if (attr->map_flags & ~BPF_F_NO_PREALLOC)
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/* reserved bits should not be used */
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return ERR_PTR(-EINVAL);
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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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/* 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 >= (1 << (KMALLOC_SHIFT_MAX - 1)) -
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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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/* 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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htab->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;
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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 = kmalloc_array(htab->n_buckets, sizeof(struct bucket),
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GFP_USER | __GFP_NOWARN);
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if (!htab->buckets) {
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htab->buckets = vmalloc(htab->n_buckets * 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_HEAD(&htab->buckets[i].head);
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raw_spin_lock_init(&htab->buckets[i].lock);
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}
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if (!percpu) {
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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 (!(attr->map_flags & BPF_F_NO_PREALLOC)) {
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err = prealloc_elems_and_freelist(htab);
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if (err)
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goto free_extra_elems;
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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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kvfree(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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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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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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static inline struct hlist_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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static struct htab_elem *lookup_elem_raw(struct hlist_head *head, u32 hash,
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void *key, u32 key_size)
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{
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struct htab_elem *l;
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hlist_for_each_entry_rcu(l, head, hash_node)
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if (l->hash == hash && !memcmp(&l->key, key, key_size))
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return l;
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return NULL;
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}
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/* Called from syscall or from eBPF program */
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static void *__htab_map_lookup_elem(struct bpf_map *map, void *key)
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{
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struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
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struct hlist_head *head;
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struct htab_elem *l;
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u32 hash, key_size;
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/* Must be called with rcu_read_lock. */
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WARN_ON_ONCE(!rcu_read_lock_held());
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key_size = map->key_size;
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hash = htab_map_hash(key, key_size);
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head = select_bucket(htab, hash);
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l = lookup_elem_raw(head, hash, key, key_size);
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return l;
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}
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static void *htab_map_lookup_elem(struct bpf_map *map, void *key)
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{
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struct htab_elem *l = __htab_map_lookup_elem(map, key);
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if (l)
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return l->key + round_up(map->key_size, 8);
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return NULL;
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}
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/* Called from syscall */
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static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
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{
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struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
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struct hlist_head *head;
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struct htab_elem *l, *next_l;
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u32 hash, key_size;
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int i;
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WARN_ON_ONCE(!rcu_read_lock_held());
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key_size = map->key_size;
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hash = htab_map_hash(key, key_size);
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head = select_bucket(htab, hash);
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/* lookup the key */
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l = lookup_elem_raw(head, hash, key, key_size);
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if (!l) {
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i = 0;
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goto find_first_elem;
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}
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/* key was found, get next key in the same bucket */
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next_l = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&l->hash_node)),
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struct htab_elem, hash_node);
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if (next_l) {
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/* if next elem in this hash list is non-zero, just return it */
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memcpy(next_key, next_l->key, key_size);
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return 0;
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}
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/* no more elements in this hash list, go to the next bucket */
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i = hash & (htab->n_buckets - 1);
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i++;
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find_first_elem:
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/* iterate over buckets */
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for (; i < htab->n_buckets; i++) {
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head = select_bucket(htab, i);
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/* pick first element in the bucket */
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next_l = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
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struct htab_elem, hash_node);
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if (next_l) {
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/* if it's not empty, just return it */
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memcpy(next_key, next_l->key, key_size);
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return 0;
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}
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}
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/* iterated over all buckets and all elements */
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return -ENOENT;
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}
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static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
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{
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if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
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free_percpu(htab_elem_get_ptr(l, htab->map.key_size));
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kfree(l);
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}
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static void htab_elem_free_rcu(struct rcu_head *head)
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{
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struct htab_elem *l = container_of(head, struct htab_elem, rcu);
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struct bpf_htab *htab = l->htab;
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/* must increment bpf_prog_active to avoid kprobe+bpf triggering while
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* we're calling kfree, otherwise deadlock is possible if kprobes
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* are placed somewhere inside of slub
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*/
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preempt_disable();
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__this_cpu_inc(bpf_prog_active);
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htab_elem_free(htab, l);
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__this_cpu_dec(bpf_prog_active);
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preempt_enable();
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}
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static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
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{
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if (l->state == HTAB_EXTRA_ELEM_USED) {
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l->state = HTAB_EXTRA_ELEM_FREE;
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return;
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}
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if (!(htab->map.map_flags & BPF_F_NO_PREALLOC)) {
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pcpu_freelist_push(&htab->freelist, &l->fnode);
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} else {
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atomic_dec(&htab->count);
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l->htab = htab;
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call_rcu(&l->rcu, htab_elem_free_rcu);
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}
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}
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static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
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void *value, u32 key_size, u32 hash,
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bool percpu, bool onallcpus,
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bool old_elem_exists)
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{
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u32 size = htab->map.value_size;
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bool prealloc = !(htab->map.map_flags & BPF_F_NO_PREALLOC);
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struct htab_elem *l_new;
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void __percpu *pptr;
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int err = 0;
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if (prealloc) {
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l_new = (struct htab_elem *)pcpu_freelist_pop(&htab->freelist);
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if (!l_new)
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err = -E2BIG;
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} else {
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if (atomic_inc_return(&htab->count) > htab->map.max_entries) {
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atomic_dec(&htab->count);
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err = -E2BIG;
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} else {
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l_new = kmalloc(htab->elem_size,
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GFP_ATOMIC | __GFP_NOWARN);
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if (!l_new)
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return ERR_PTR(-ENOMEM);
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}
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}
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if (err) {
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if (!old_elem_exists)
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return ERR_PTR(err);
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/* if we're updating the existing element and the hash table
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* is full, use per-cpu extra elems
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*/
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l_new = this_cpu_ptr(htab->extra_elems);
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if (l_new->state != HTAB_EXTRA_ELEM_FREE)
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return ERR_PTR(-E2BIG);
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l_new->state = HTAB_EXTRA_ELEM_USED;
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} else {
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l_new->state = HTAB_NOT_AN_EXTRA_ELEM;
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}
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memcpy(l_new->key, key, key_size);
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if (percpu) {
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/* round up value_size to 8 bytes */
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size = round_up(size, 8);
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if (prealloc) {
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pptr = htab_elem_get_ptr(l_new, key_size);
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} else {
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/* alloc_percpu zero-fills */
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pptr = __alloc_percpu_gfp(size, 8,
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GFP_ATOMIC | __GFP_NOWARN);
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if (!pptr) {
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kfree(l_new);
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return ERR_PTR(-ENOMEM);
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}
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}
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if (!onallcpus) {
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/* copy true value_size bytes */
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memcpy(this_cpu_ptr(pptr), value, htab->map.value_size);
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|
} else {
|
|
int off = 0, cpu;
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
bpf_long_memcpy(per_cpu_ptr(pptr, cpu),
|
|
value + off, size);
|
|
off += size;
|
|
}
|
|
}
|
|
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_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_add_head_rcu(&l_new->hash_node, head);
|
|
if (l_old) {
|
|
hlist_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_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_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) {
|
|
void __percpu *pptr = htab_elem_get_ptr(l_old, key_size);
|
|
u32 size = htab->map.value_size;
|
|
|
|
/* per-cpu hash map can update value in-place */
|
|
if (!onallcpus) {
|
|
memcpy(this_cpu_ptr(pptr), value, size);
|
|
} else {
|
|
int off = 0, cpu;
|
|
|
|
size = round_up(size, 8);
|
|
for_each_possible_cpu(cpu) {
|
|
bpf_long_memcpy(per_cpu_ptr(pptr, cpu),
|
|
value + off, size);
|
|
off += size;
|
|
}
|
|
}
|
|
} 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_add_head_rcu(&l_new->hash_node, head);
|
|
}
|
|
ret = 0;
|
|
err:
|
|
raw_spin_unlock_irqrestore(&b->lock, flags);
|
|
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);
|
|
}
|
|
|
|
/* 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_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_del_rcu(&l->hash_node);
|
|
free_htab_elem(htab, l);
|
|
ret = 0;
|
|
}
|
|
|
|
raw_spin_unlock_irqrestore(&b->lock, flags);
|
|
return ret;
|
|
}
|
|
|
|
static void delete_all_elements(struct bpf_htab *htab)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < htab->n_buckets; i++) {
|
|
struct hlist_head *head = select_bucket(htab, i);
|
|
struct hlist_node *n;
|
|
struct htab_elem *l;
|
|
|
|
hlist_for_each_entry_safe(l, n, head, hash_node) {
|
|
hlist_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 {
|
|
htab_free_elems(htab);
|
|
pcpu_freelist_destroy(&htab->freelist);
|
|
}
|
|
free_percpu(htab->extra_elems);
|
|
kvfree(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 __read_mostly = {
|
|
.ops = &htab_ops,
|
|
.type = BPF_MAP_TYPE_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;
|
|
}
|
|
|
|
int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value)
|
|
{
|
|
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;
|
|
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)
|
|
{
|
|
int ret;
|
|
|
|
rcu_read_lock();
|
|
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 __read_mostly = {
|
|
.ops = &htab_percpu_ops,
|
|
.type = BPF_MAP_TYPE_PERCPU_HASH,
|
|
};
|
|
|
|
static int __init register_htab_map(void)
|
|
{
|
|
bpf_register_map_type(&htab_type);
|
|
bpf_register_map_type(&htab_percpu_type);
|
|
return 0;
|
|
}
|
|
late_initcall(register_htab_map);
|