798 lines
23 KiB
C
798 lines
23 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2019 Facebook */
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#include <linux/rculist.h>
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#include <linux/list.h>
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#include <linux/hash.h>
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#include <linux/types.h>
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#include <linux/spinlock.h>
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#include <linux/bpf.h>
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#include <linux/btf_ids.h>
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#include <linux/bpf_local_storage.h>
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#include <net/sock.h>
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#include <uapi/linux/sock_diag.h>
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#include <uapi/linux/btf.h>
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#include <linux/rcupdate.h>
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#include <linux/rcupdate_trace.h>
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#include <linux/rcupdate_wait.h>
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#define BPF_LOCAL_STORAGE_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_CLONE)
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static struct bpf_local_storage_map_bucket *
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select_bucket(struct bpf_local_storage_map *smap,
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struct bpf_local_storage_elem *selem)
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{
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return &smap->buckets[hash_ptr(selem, smap->bucket_log)];
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}
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static int mem_charge(struct bpf_local_storage_map *smap, void *owner, u32 size)
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{
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struct bpf_map *map = &smap->map;
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if (!map->ops->map_local_storage_charge)
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return 0;
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return map->ops->map_local_storage_charge(smap, owner, size);
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}
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static void mem_uncharge(struct bpf_local_storage_map *smap, void *owner,
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u32 size)
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{
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struct bpf_map *map = &smap->map;
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if (map->ops->map_local_storage_uncharge)
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map->ops->map_local_storage_uncharge(smap, owner, size);
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}
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static struct bpf_local_storage __rcu **
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owner_storage(struct bpf_local_storage_map *smap, void *owner)
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{
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struct bpf_map *map = &smap->map;
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return map->ops->map_owner_storage_ptr(owner);
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}
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static bool selem_linked_to_storage_lockless(const struct bpf_local_storage_elem *selem)
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{
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return !hlist_unhashed_lockless(&selem->snode);
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}
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static bool selem_linked_to_storage(const struct bpf_local_storage_elem *selem)
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{
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return !hlist_unhashed(&selem->snode);
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}
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static bool selem_linked_to_map_lockless(const struct bpf_local_storage_elem *selem)
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{
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return !hlist_unhashed_lockless(&selem->map_node);
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}
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static bool selem_linked_to_map(const struct bpf_local_storage_elem *selem)
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{
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return !hlist_unhashed(&selem->map_node);
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}
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struct bpf_local_storage_elem *
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bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner,
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void *value, bool charge_mem, gfp_t gfp_flags)
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{
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struct bpf_local_storage_elem *selem;
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if (charge_mem && mem_charge(smap, owner, smap->elem_size))
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return NULL;
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selem = bpf_map_kzalloc(&smap->map, smap->elem_size,
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gfp_flags | __GFP_NOWARN);
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if (selem) {
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if (value)
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copy_map_value(&smap->map, SDATA(selem)->data, value);
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/* No need to call check_and_init_map_value as memory is zero init */
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return selem;
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}
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if (charge_mem)
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mem_uncharge(smap, owner, smap->elem_size);
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return NULL;
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}
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void bpf_local_storage_free_rcu(struct rcu_head *rcu)
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{
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struct bpf_local_storage *local_storage;
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/* If RCU Tasks Trace grace period implies RCU grace period, do
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* kfree(), else do kfree_rcu().
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*/
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local_storage = container_of(rcu, struct bpf_local_storage, rcu);
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if (rcu_trace_implies_rcu_gp())
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kfree(local_storage);
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else
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kfree_rcu(local_storage, rcu);
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}
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static void bpf_selem_free_fields_rcu(struct rcu_head *rcu)
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{
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struct bpf_local_storage_elem *selem;
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struct bpf_local_storage_map *smap;
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selem = container_of(rcu, struct bpf_local_storage_elem, rcu);
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/* protected by the rcu_barrier*() */
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smap = rcu_dereference_protected(SDATA(selem)->smap, true);
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bpf_obj_free_fields(smap->map.record, SDATA(selem)->data);
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kfree(selem);
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}
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static void bpf_selem_free_fields_trace_rcu(struct rcu_head *rcu)
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{
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/* Free directly if Tasks Trace RCU GP also implies RCU GP */
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if (rcu_trace_implies_rcu_gp())
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bpf_selem_free_fields_rcu(rcu);
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else
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call_rcu(rcu, bpf_selem_free_fields_rcu);
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}
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static void bpf_selem_free_trace_rcu(struct rcu_head *rcu)
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{
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struct bpf_local_storage_elem *selem;
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selem = container_of(rcu, struct bpf_local_storage_elem, rcu);
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if (rcu_trace_implies_rcu_gp())
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kfree(selem);
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else
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kfree_rcu(selem, rcu);
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}
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/* local_storage->lock must be held and selem->local_storage == local_storage.
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* The caller must ensure selem->smap is still valid to be
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* dereferenced for its smap->elem_size and smap->cache_idx.
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*/
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static bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage,
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struct bpf_local_storage_elem *selem,
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bool uncharge_mem, bool use_trace_rcu)
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{
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struct bpf_local_storage_map *smap;
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bool free_local_storage;
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struct btf_record *rec;
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void *owner;
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smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held());
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owner = local_storage->owner;
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/* All uncharging on the owner must be done first.
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* The owner may be freed once the last selem is unlinked
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* from local_storage.
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*/
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if (uncharge_mem)
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mem_uncharge(smap, owner, smap->elem_size);
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free_local_storage = hlist_is_singular_node(&selem->snode,
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&local_storage->list);
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if (free_local_storage) {
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mem_uncharge(smap, owner, sizeof(struct bpf_local_storage));
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local_storage->owner = NULL;
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/* After this RCU_INIT, owner may be freed and cannot be used */
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RCU_INIT_POINTER(*owner_storage(smap, owner), NULL);
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/* local_storage is not freed now. local_storage->lock is
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* still held and raw_spin_unlock_bh(&local_storage->lock)
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* will be done by the caller.
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*
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* Although the unlock will be done under
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* rcu_read_lock(), it is more intuitive to
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* read if the freeing of the storage is done
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* after the raw_spin_unlock_bh(&local_storage->lock).
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*
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* Hence, a "bool free_local_storage" is returned
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* to the caller which then calls then frees the storage after
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* all the RCU grace periods have expired.
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*/
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}
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hlist_del_init_rcu(&selem->snode);
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if (rcu_access_pointer(local_storage->cache[smap->cache_idx]) ==
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SDATA(selem))
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RCU_INIT_POINTER(local_storage->cache[smap->cache_idx], NULL);
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/* A different RCU callback is chosen whenever we need to free
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* additional fields in selem data before freeing selem.
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* bpf_local_storage_map_free only executes rcu_barrier to wait for RCU
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* callbacks when it has special fields, hence we can only conditionally
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* dereference smap, as by this time the map might have already been
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* freed without waiting for our call_rcu callback if it did not have
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* any special fields.
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*/
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rec = smap->map.record;
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if (use_trace_rcu) {
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if (!IS_ERR_OR_NULL(rec))
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call_rcu_tasks_trace(&selem->rcu, bpf_selem_free_fields_trace_rcu);
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else
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call_rcu_tasks_trace(&selem->rcu, bpf_selem_free_trace_rcu);
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} else {
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if (!IS_ERR_OR_NULL(rec))
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call_rcu(&selem->rcu, bpf_selem_free_fields_rcu);
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else
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kfree_rcu(selem, rcu);
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}
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return free_local_storage;
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}
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static void __bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem,
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bool use_trace_rcu)
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{
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struct bpf_local_storage *local_storage;
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bool free_local_storage = false;
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unsigned long flags;
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if (unlikely(!selem_linked_to_storage_lockless(selem)))
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/* selem has already been unlinked from sk */
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return;
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local_storage = rcu_dereference_check(selem->local_storage,
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bpf_rcu_lock_held());
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raw_spin_lock_irqsave(&local_storage->lock, flags);
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if (likely(selem_linked_to_storage(selem)))
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free_local_storage = bpf_selem_unlink_storage_nolock(
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local_storage, selem, true, use_trace_rcu);
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raw_spin_unlock_irqrestore(&local_storage->lock, flags);
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if (free_local_storage) {
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if (use_trace_rcu)
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call_rcu_tasks_trace(&local_storage->rcu,
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bpf_local_storage_free_rcu);
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else
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kfree_rcu(local_storage, rcu);
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}
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}
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void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage,
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struct bpf_local_storage_elem *selem)
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{
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RCU_INIT_POINTER(selem->local_storage, local_storage);
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hlist_add_head_rcu(&selem->snode, &local_storage->list);
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}
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void bpf_selem_unlink_map(struct bpf_local_storage_elem *selem)
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{
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struct bpf_local_storage_map *smap;
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struct bpf_local_storage_map_bucket *b;
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unsigned long flags;
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if (unlikely(!selem_linked_to_map_lockless(selem)))
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/* selem has already be unlinked from smap */
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return;
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smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held());
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b = select_bucket(smap, selem);
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raw_spin_lock_irqsave(&b->lock, flags);
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if (likely(selem_linked_to_map(selem)))
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hlist_del_init_rcu(&selem->map_node);
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raw_spin_unlock_irqrestore(&b->lock, flags);
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}
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void bpf_selem_link_map(struct bpf_local_storage_map *smap,
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struct bpf_local_storage_elem *selem)
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{
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struct bpf_local_storage_map_bucket *b = select_bucket(smap, selem);
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unsigned long flags;
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raw_spin_lock_irqsave(&b->lock, flags);
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RCU_INIT_POINTER(SDATA(selem)->smap, smap);
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hlist_add_head_rcu(&selem->map_node, &b->list);
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raw_spin_unlock_irqrestore(&b->lock, flags);
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}
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void bpf_selem_unlink(struct bpf_local_storage_elem *selem, bool use_trace_rcu)
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{
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/* Always unlink from map before unlinking from local_storage
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* because selem will be freed after successfully unlinked from
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* the local_storage.
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*/
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bpf_selem_unlink_map(selem);
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__bpf_selem_unlink_storage(selem, use_trace_rcu);
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}
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/* If cacheit_lockit is false, this lookup function is lockless */
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struct bpf_local_storage_data *
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bpf_local_storage_lookup(struct bpf_local_storage *local_storage,
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struct bpf_local_storage_map *smap,
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bool cacheit_lockit)
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{
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struct bpf_local_storage_data *sdata;
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struct bpf_local_storage_elem *selem;
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/* Fast path (cache hit) */
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sdata = rcu_dereference_check(local_storage->cache[smap->cache_idx],
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bpf_rcu_lock_held());
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if (sdata && rcu_access_pointer(sdata->smap) == smap)
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return sdata;
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/* Slow path (cache miss) */
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hlist_for_each_entry_rcu(selem, &local_storage->list, snode,
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rcu_read_lock_trace_held())
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if (rcu_access_pointer(SDATA(selem)->smap) == smap)
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break;
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if (!selem)
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return NULL;
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sdata = SDATA(selem);
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if (cacheit_lockit) {
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unsigned long flags;
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/* spinlock is needed to avoid racing with the
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* parallel delete. Otherwise, publishing an already
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* deleted sdata to the cache will become a use-after-free
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* problem in the next bpf_local_storage_lookup().
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*/
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raw_spin_lock_irqsave(&local_storage->lock, flags);
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if (selem_linked_to_storage(selem))
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rcu_assign_pointer(local_storage->cache[smap->cache_idx],
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sdata);
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raw_spin_unlock_irqrestore(&local_storage->lock, flags);
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}
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return sdata;
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}
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static int check_flags(const struct bpf_local_storage_data *old_sdata,
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u64 map_flags)
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{
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if (old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST)
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/* elem already exists */
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return -EEXIST;
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if (!old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_EXIST)
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/* elem doesn't exist, cannot update it */
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return -ENOENT;
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return 0;
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}
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int bpf_local_storage_alloc(void *owner,
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struct bpf_local_storage_map *smap,
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struct bpf_local_storage_elem *first_selem,
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gfp_t gfp_flags)
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{
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struct bpf_local_storage *prev_storage, *storage;
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struct bpf_local_storage **owner_storage_ptr;
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int err;
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err = mem_charge(smap, owner, sizeof(*storage));
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if (err)
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return err;
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storage = bpf_map_kzalloc(&smap->map, sizeof(*storage),
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gfp_flags | __GFP_NOWARN);
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if (!storage) {
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err = -ENOMEM;
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goto uncharge;
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}
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INIT_HLIST_HEAD(&storage->list);
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raw_spin_lock_init(&storage->lock);
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storage->owner = owner;
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bpf_selem_link_storage_nolock(storage, first_selem);
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bpf_selem_link_map(smap, first_selem);
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owner_storage_ptr =
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(struct bpf_local_storage **)owner_storage(smap, owner);
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/* Publish storage to the owner.
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* Instead of using any lock of the kernel object (i.e. owner),
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* cmpxchg will work with any kernel object regardless what
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* the running context is, bh, irq...etc.
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*
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* From now on, the owner->storage pointer (e.g. sk->sk_bpf_storage)
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* is protected by the storage->lock. Hence, when freeing
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* the owner->storage, the storage->lock must be held before
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* setting owner->storage ptr to NULL.
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*/
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prev_storage = cmpxchg(owner_storage_ptr, NULL, storage);
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if (unlikely(prev_storage)) {
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bpf_selem_unlink_map(first_selem);
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err = -EAGAIN;
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goto uncharge;
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/* Note that even first_selem was linked to smap's
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* bucket->list, first_selem can be freed immediately
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* (instead of kfree_rcu) because
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* bpf_local_storage_map_free() does a
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* synchronize_rcu_mult (waiting for both sleepable and
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* normal programs) before walking the bucket->list.
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* Hence, no one is accessing selem from the
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* bucket->list under rcu_read_lock().
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*/
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}
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return 0;
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uncharge:
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kfree(storage);
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mem_uncharge(smap, owner, sizeof(*storage));
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return err;
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}
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/* sk cannot be going away because it is linking new elem
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* to sk->sk_bpf_storage. (i.e. sk->sk_refcnt cannot be 0).
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* Otherwise, it will become a leak (and other memory issues
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* during map destruction).
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*/
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struct bpf_local_storage_data *
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bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
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void *value, u64 map_flags, gfp_t gfp_flags)
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{
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struct bpf_local_storage_data *old_sdata = NULL;
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struct bpf_local_storage_elem *selem = NULL;
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struct bpf_local_storage *local_storage;
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unsigned long flags;
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int err;
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/* BPF_EXIST and BPF_NOEXIST cannot be both set */
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if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST) ||
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/* BPF_F_LOCK can only be used in a value with spin_lock */
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unlikely((map_flags & BPF_F_LOCK) &&
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!btf_record_has_field(smap->map.record, BPF_SPIN_LOCK)))
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return ERR_PTR(-EINVAL);
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if (gfp_flags == GFP_KERNEL && (map_flags & ~BPF_F_LOCK) != BPF_NOEXIST)
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return ERR_PTR(-EINVAL);
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local_storage = rcu_dereference_check(*owner_storage(smap, owner),
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bpf_rcu_lock_held());
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if (!local_storage || hlist_empty(&local_storage->list)) {
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/* Very first elem for the owner */
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err = check_flags(NULL, map_flags);
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if (err)
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return ERR_PTR(err);
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selem = bpf_selem_alloc(smap, owner, value, true, gfp_flags);
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if (!selem)
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return ERR_PTR(-ENOMEM);
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err = bpf_local_storage_alloc(owner, smap, selem, gfp_flags);
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if (err) {
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kfree(selem);
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mem_uncharge(smap, owner, smap->elem_size);
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return ERR_PTR(err);
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}
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return SDATA(selem);
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}
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if ((map_flags & BPF_F_LOCK) && !(map_flags & BPF_NOEXIST)) {
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/* Hoping to find an old_sdata to do inline update
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* such that it can avoid taking the local_storage->lock
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* and changing the lists.
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*/
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old_sdata =
|
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bpf_local_storage_lookup(local_storage, smap, false);
|
|
err = check_flags(old_sdata, map_flags);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
if (old_sdata && selem_linked_to_storage_lockless(SELEM(old_sdata))) {
|
|
copy_map_value_locked(&smap->map, old_sdata->data,
|
|
value, false);
|
|
return old_sdata;
|
|
}
|
|
}
|
|
|
|
if (gfp_flags == GFP_KERNEL) {
|
|
selem = bpf_selem_alloc(smap, owner, value, true, gfp_flags);
|
|
if (!selem)
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
raw_spin_lock_irqsave(&local_storage->lock, flags);
|
|
|
|
/* Recheck local_storage->list under local_storage->lock */
|
|
if (unlikely(hlist_empty(&local_storage->list))) {
|
|
/* A parallel del is happening and local_storage is going
|
|
* away. It has just been checked before, so very
|
|
* unlikely. Return instead of retry to keep things
|
|
* simple.
|
|
*/
|
|
err = -EAGAIN;
|
|
goto unlock_err;
|
|
}
|
|
|
|
old_sdata = bpf_local_storage_lookup(local_storage, smap, false);
|
|
err = check_flags(old_sdata, map_flags);
|
|
if (err)
|
|
goto unlock_err;
|
|
|
|
if (old_sdata && (map_flags & BPF_F_LOCK)) {
|
|
copy_map_value_locked(&smap->map, old_sdata->data, value,
|
|
false);
|
|
selem = SELEM(old_sdata);
|
|
goto unlock;
|
|
}
|
|
|
|
if (gfp_flags != GFP_KERNEL) {
|
|
/* local_storage->lock is held. Hence, we are sure
|
|
* we can unlink and uncharge the old_sdata successfully
|
|
* later. Hence, instead of charging the new selem now
|
|
* and then uncharge the old selem later (which may cause
|
|
* a potential but unnecessary charge failure), avoid taking
|
|
* a charge at all here (the "!old_sdata" check) and the
|
|
* old_sdata will not be uncharged later during
|
|
* bpf_selem_unlink_storage_nolock().
|
|
*/
|
|
selem = bpf_selem_alloc(smap, owner, value, !old_sdata, gfp_flags);
|
|
if (!selem) {
|
|
err = -ENOMEM;
|
|
goto unlock_err;
|
|
}
|
|
}
|
|
|
|
/* First, link the new selem to the map */
|
|
bpf_selem_link_map(smap, selem);
|
|
|
|
/* Second, link (and publish) the new selem to local_storage */
|
|
bpf_selem_link_storage_nolock(local_storage, selem);
|
|
|
|
/* Third, remove old selem, SELEM(old_sdata) */
|
|
if (old_sdata) {
|
|
bpf_selem_unlink_map(SELEM(old_sdata));
|
|
bpf_selem_unlink_storage_nolock(local_storage, SELEM(old_sdata),
|
|
false, true);
|
|
}
|
|
|
|
unlock:
|
|
raw_spin_unlock_irqrestore(&local_storage->lock, flags);
|
|
return SDATA(selem);
|
|
|
|
unlock_err:
|
|
raw_spin_unlock_irqrestore(&local_storage->lock, flags);
|
|
if (selem) {
|
|
mem_uncharge(smap, owner, smap->elem_size);
|
|
kfree(selem);
|
|
}
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
static u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache)
|
|
{
|
|
u64 min_usage = U64_MAX;
|
|
u16 i, res = 0;
|
|
|
|
spin_lock(&cache->idx_lock);
|
|
|
|
for (i = 0; i < BPF_LOCAL_STORAGE_CACHE_SIZE; i++) {
|
|
if (cache->idx_usage_counts[i] < min_usage) {
|
|
min_usage = cache->idx_usage_counts[i];
|
|
res = i;
|
|
|
|
/* Found a free cache_idx */
|
|
if (!min_usage)
|
|
break;
|
|
}
|
|
}
|
|
cache->idx_usage_counts[res]++;
|
|
|
|
spin_unlock(&cache->idx_lock);
|
|
|
|
return res;
|
|
}
|
|
|
|
static void bpf_local_storage_cache_idx_free(struct bpf_local_storage_cache *cache,
|
|
u16 idx)
|
|
{
|
|
spin_lock(&cache->idx_lock);
|
|
cache->idx_usage_counts[idx]--;
|
|
spin_unlock(&cache->idx_lock);
|
|
}
|
|
|
|
int bpf_local_storage_map_alloc_check(union bpf_attr *attr)
|
|
{
|
|
if (attr->map_flags & ~BPF_LOCAL_STORAGE_CREATE_FLAG_MASK ||
|
|
!(attr->map_flags & BPF_F_NO_PREALLOC) ||
|
|
attr->max_entries ||
|
|
attr->key_size != sizeof(int) || !attr->value_size ||
|
|
/* Enforce BTF for userspace sk dumping */
|
|
!attr->btf_key_type_id || !attr->btf_value_type_id)
|
|
return -EINVAL;
|
|
|
|
if (!bpf_capable())
|
|
return -EPERM;
|
|
|
|
if (attr->value_size > BPF_LOCAL_STORAGE_MAX_VALUE_SIZE)
|
|
return -E2BIG;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct bpf_local_storage_map *__bpf_local_storage_map_alloc(union bpf_attr *attr)
|
|
{
|
|
struct bpf_local_storage_map *smap;
|
|
unsigned int i;
|
|
u32 nbuckets;
|
|
|
|
smap = bpf_map_area_alloc(sizeof(*smap), NUMA_NO_NODE);
|
|
if (!smap)
|
|
return ERR_PTR(-ENOMEM);
|
|
bpf_map_init_from_attr(&smap->map, attr);
|
|
|
|
nbuckets = roundup_pow_of_two(num_possible_cpus());
|
|
/* Use at least 2 buckets, select_bucket() is undefined behavior with 1 bucket */
|
|
nbuckets = max_t(u32, 2, nbuckets);
|
|
smap->bucket_log = ilog2(nbuckets);
|
|
|
|
smap->buckets = bpf_map_kvcalloc(&smap->map, sizeof(*smap->buckets),
|
|
nbuckets, GFP_USER | __GFP_NOWARN);
|
|
if (!smap->buckets) {
|
|
bpf_map_area_free(smap);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
for (i = 0; i < nbuckets; i++) {
|
|
INIT_HLIST_HEAD(&smap->buckets[i].list);
|
|
raw_spin_lock_init(&smap->buckets[i].lock);
|
|
}
|
|
|
|
smap->elem_size = offsetof(struct bpf_local_storage_elem,
|
|
sdata.data[attr->value_size]);
|
|
|
|
return smap;
|
|
}
|
|
|
|
int bpf_local_storage_map_check_btf(const struct bpf_map *map,
|
|
const struct btf *btf,
|
|
const struct btf_type *key_type,
|
|
const struct btf_type *value_type)
|
|
{
|
|
u32 int_data;
|
|
|
|
if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
|
|
return -EINVAL;
|
|
|
|
int_data = *(u32 *)(key_type + 1);
|
|
if (BTF_INT_BITS(int_data) != 32 || BTF_INT_OFFSET(int_data))
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
bool bpf_local_storage_unlink_nolock(struct bpf_local_storage *local_storage)
|
|
{
|
|
struct bpf_local_storage_elem *selem;
|
|
bool free_storage = false;
|
|
struct hlist_node *n;
|
|
|
|
/* Neither the bpf_prog nor the bpf_map's syscall
|
|
* could be modifying the local_storage->list now.
|
|
* Thus, no elem can be added to or deleted from the
|
|
* local_storage->list by the bpf_prog or by the bpf_map's syscall.
|
|
*
|
|
* It is racing with bpf_local_storage_map_free() alone
|
|
* when unlinking elem from the local_storage->list and
|
|
* the map's bucket->list.
|
|
*/
|
|
hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) {
|
|
/* Always unlink from map before unlinking from
|
|
* local_storage.
|
|
*/
|
|
bpf_selem_unlink_map(selem);
|
|
/* If local_storage list has only one element, the
|
|
* bpf_selem_unlink_storage_nolock() will return true.
|
|
* Otherwise, it will return false. The current loop iteration
|
|
* intends to remove all local storage. So the last iteration
|
|
* of the loop will set the free_cgroup_storage to true.
|
|
*/
|
|
free_storage = bpf_selem_unlink_storage_nolock(
|
|
local_storage, selem, false, false);
|
|
}
|
|
|
|
return free_storage;
|
|
}
|
|
|
|
u64 bpf_local_storage_map_mem_usage(const struct bpf_map *map)
|
|
{
|
|
struct bpf_local_storage_map *smap = (struct bpf_local_storage_map *)map;
|
|
u64 usage = sizeof(*smap);
|
|
|
|
/* The dynamically callocated selems are not counted currently. */
|
|
usage += sizeof(*smap->buckets) * (1ULL << smap->bucket_log);
|
|
return usage;
|
|
}
|
|
|
|
struct bpf_map *
|
|
bpf_local_storage_map_alloc(union bpf_attr *attr,
|
|
struct bpf_local_storage_cache *cache)
|
|
{
|
|
struct bpf_local_storage_map *smap;
|
|
|
|
smap = __bpf_local_storage_map_alloc(attr);
|
|
if (IS_ERR(smap))
|
|
return ERR_CAST(smap);
|
|
|
|
smap->cache_idx = bpf_local_storage_cache_idx_get(cache);
|
|
return &smap->map;
|
|
}
|
|
|
|
void bpf_local_storage_map_free(struct bpf_map *map,
|
|
struct bpf_local_storage_cache *cache,
|
|
int __percpu *busy_counter)
|
|
{
|
|
struct bpf_local_storage_map_bucket *b;
|
|
struct bpf_local_storage_elem *selem;
|
|
struct bpf_local_storage_map *smap;
|
|
unsigned int i;
|
|
|
|
smap = (struct bpf_local_storage_map *)map;
|
|
bpf_local_storage_cache_idx_free(cache, smap->cache_idx);
|
|
|
|
/* Note that this map might be concurrently cloned from
|
|
* bpf_sk_storage_clone. Wait for any existing bpf_sk_storage_clone
|
|
* RCU read section to finish before proceeding. New RCU
|
|
* read sections should be prevented via bpf_map_inc_not_zero.
|
|
*/
|
|
synchronize_rcu();
|
|
|
|
/* bpf prog and the userspace can no longer access this map
|
|
* now. No new selem (of this map) can be added
|
|
* to the owner->storage or to the map bucket's list.
|
|
*
|
|
* The elem of this map can be cleaned up here
|
|
* or when the storage is freed e.g.
|
|
* by bpf_sk_storage_free() during __sk_destruct().
|
|
*/
|
|
for (i = 0; i < (1U << smap->bucket_log); i++) {
|
|
b = &smap->buckets[i];
|
|
|
|
rcu_read_lock();
|
|
/* No one is adding to b->list now */
|
|
while ((selem = hlist_entry_safe(
|
|
rcu_dereference_raw(hlist_first_rcu(&b->list)),
|
|
struct bpf_local_storage_elem, map_node))) {
|
|
if (busy_counter) {
|
|
migrate_disable();
|
|
this_cpu_inc(*busy_counter);
|
|
}
|
|
bpf_selem_unlink(selem, false);
|
|
if (busy_counter) {
|
|
this_cpu_dec(*busy_counter);
|
|
migrate_enable();
|
|
}
|
|
cond_resched_rcu();
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/* While freeing the storage we may still need to access the map.
|
|
*
|
|
* e.g. when bpf_sk_storage_free() has unlinked selem from the map
|
|
* which then made the above while((selem = ...)) loop
|
|
* exit immediately.
|
|
*
|
|
* However, while freeing the storage one still needs to access the
|
|
* smap->elem_size to do the uncharging in
|
|
* bpf_selem_unlink_storage_nolock().
|
|
*
|
|
* Hence, wait another rcu grace period for the storage to be freed.
|
|
*/
|
|
synchronize_rcu();
|
|
|
|
/* Only delay freeing of smap, buckets are not needed anymore */
|
|
kvfree(smap->buckets);
|
|
|
|
/* When local storage has special fields, callbacks for
|
|
* bpf_selem_free_fields_rcu and bpf_selem_free_fields_trace_rcu will
|
|
* keep using the map BTF record, we need to execute an RCU barrier to
|
|
* wait for them as the record will be freed right after our map_free
|
|
* callback.
|
|
*/
|
|
if (!IS_ERR_OR_NULL(smap->map.record)) {
|
|
rcu_barrier_tasks_trace();
|
|
/* We cannot skip rcu_barrier() when rcu_trace_implies_rcu_gp()
|
|
* is true, because while call_rcu invocation is skipped in that
|
|
* case in bpf_selem_free_fields_trace_rcu (and all local
|
|
* storage maps pass use_trace_rcu = true), there can be
|
|
* call_rcu callbacks based on use_trace_rcu = false in the
|
|
* while ((selem = ...)) loop above or when owner's free path
|
|
* calls bpf_local_storage_unlink_nolock.
|
|
*/
|
|
rcu_barrier();
|
|
}
|
|
bpf_map_area_free(smap);
|
|
}
|