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![Martin KaFai Lau](/assets/img/avatar_default.png)
The commitc83597fa5d
("bpf: Refactor some inode/task/sk storage functions for reuse"), refactored the bpf_{sk,task,inode}_storage_free() into bpf_local_storage_unlink_nolock() which then later renamed to bpf_local_storage_destroy(). The commit accidentally passed the "bool uncharge_mem = false" argument to bpf_selem_unlink_storage_nolock() which then stopped the uncharge from happening to the sk->sk_omem_alloc. This missing uncharge only happens when the sk is going away (during __sk_destruct). This patch fixes it by always passing "uncharge_mem = true". It is a noop to the task/inode/cgroup storage because they do not have the map_local_storage_(un)charge enabled in the map_ops. A followup patch will be done in bpf-next to remove the uncharge_mem argument. A selftest is added in the next patch. Fixes:c83597fa5d
("bpf: Refactor some inode/task/sk storage functions for reuse") Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20230901231129.578493-3-martin.lau@linux.dev
917 lines
26 KiB
C
917 lines
26 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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if (smap->bpf_ma) {
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migrate_disable();
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selem = bpf_mem_cache_alloc_flags(&smap->selem_ma, gfp_flags);
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migrate_enable();
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if (selem)
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/* Keep the original bpf_map_kzalloc behavior
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* before started using the bpf_mem_cache_alloc.
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*
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* No need to use zero_map_value. The bpf_selem_free()
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* only does bpf_mem_cache_free when there is
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* no other bpf prog is using the selem.
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*/
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memset(SDATA(selem)->data, 0, smap->map.value_size);
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} else {
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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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}
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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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/* rcu tasks trace callback for bpf_ma == false */
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static void __bpf_local_storage_free_trace_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_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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local_storage = container_of(rcu, struct bpf_local_storage, rcu);
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bpf_mem_cache_raw_free(local_storage);
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}
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static void bpf_local_storage_free_trace_rcu(struct rcu_head *rcu)
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{
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if (rcu_trace_implies_rcu_gp())
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bpf_local_storage_free_rcu(rcu);
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else
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call_rcu(rcu, bpf_local_storage_free_rcu);
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}
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/* Handle bpf_ma == false */
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static void __bpf_local_storage_free(struct bpf_local_storage *local_storage,
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bool vanilla_rcu)
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{
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if (vanilla_rcu)
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kfree_rcu(local_storage, rcu);
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else
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call_rcu_tasks_trace(&local_storage->rcu,
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__bpf_local_storage_free_trace_rcu);
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}
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static void bpf_local_storage_free(struct bpf_local_storage *local_storage,
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struct bpf_local_storage_map *smap,
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bool bpf_ma, bool reuse_now)
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{
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if (!local_storage)
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return;
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if (!bpf_ma) {
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__bpf_local_storage_free(local_storage, reuse_now);
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return;
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}
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if (!reuse_now) {
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call_rcu_tasks_trace(&local_storage->rcu,
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bpf_local_storage_free_trace_rcu);
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return;
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}
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if (smap) {
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migrate_disable();
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bpf_mem_cache_free(&smap->storage_ma, local_storage);
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migrate_enable();
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} else {
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/* smap could be NULL if the selem that triggered
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* this 'local_storage' creation had been long gone.
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* In this case, directly do call_rcu().
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*/
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call_rcu(&local_storage->rcu, bpf_local_storage_free_rcu);
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}
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}
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/* rcu tasks trace callback for bpf_ma == false */
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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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/* Handle bpf_ma == false */
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static void __bpf_selem_free(struct bpf_local_storage_elem *selem,
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bool vanilla_rcu)
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{
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if (vanilla_rcu)
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kfree_rcu(selem, 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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}
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static void bpf_selem_free_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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bpf_mem_cache_raw_free(selem);
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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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if (rcu_trace_implies_rcu_gp())
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bpf_selem_free_rcu(rcu);
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else
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call_rcu(rcu, bpf_selem_free_rcu);
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}
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void bpf_selem_free(struct bpf_local_storage_elem *selem,
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struct bpf_local_storage_map *smap,
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bool reuse_now)
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{
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bpf_obj_free_fields(smap->map.record, SDATA(selem)->data);
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if (!smap->bpf_ma) {
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__bpf_selem_free(selem, reuse_now);
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return;
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}
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if (!reuse_now) {
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call_rcu_tasks_trace(&selem->rcu, bpf_selem_free_trace_rcu);
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} else {
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/* Instead of using the vanilla call_rcu(),
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* bpf_mem_cache_free will be able to reuse selem
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* immediately.
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*/
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migrate_disable();
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bpf_mem_cache_free(&smap->selem_ma, selem);
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migrate_enable();
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}
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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 reuse_now)
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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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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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bpf_selem_free(selem, smap, reuse_now);
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if (rcu_access_pointer(local_storage->smap) == smap)
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RCU_INIT_POINTER(local_storage->smap, NULL);
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return free_local_storage;
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}
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static bool check_storage_bpf_ma(struct bpf_local_storage *local_storage,
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struct bpf_local_storage_map *storage_smap,
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struct bpf_local_storage_elem *selem)
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{
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struct bpf_local_storage_map *selem_smap;
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/* local_storage->smap may be NULL. If it is, get the bpf_ma
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* from any selem in the local_storage->list. The bpf_ma of all
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* local_storage and selem should have the same value
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* for the same map type.
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*
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* If the local_storage->list is already empty, the caller will not
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* care about the bpf_ma value also because the caller is not
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* responsibile to free the local_storage.
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*/
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if (storage_smap)
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return storage_smap->bpf_ma;
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if (!selem) {
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struct hlist_node *n;
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n = rcu_dereference_check(hlist_first_rcu(&local_storage->list),
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bpf_rcu_lock_held());
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if (!n)
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return false;
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selem = hlist_entry(n, struct bpf_local_storage_elem, snode);
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}
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selem_smap = rcu_dereference_check(SDATA(selem)->smap, bpf_rcu_lock_held());
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return selem_smap->bpf_ma;
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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 reuse_now)
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{
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struct bpf_local_storage_map *storage_smap;
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struct bpf_local_storage *local_storage;
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bool bpf_ma, 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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storage_smap = rcu_dereference_check(local_storage->smap,
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bpf_rcu_lock_held());
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bpf_ma = check_storage_bpf_ma(local_storage, storage_smap, selem);
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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, reuse_now);
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raw_spin_unlock_irqrestore(&local_storage->lock, flags);
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if (free_local_storage)
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bpf_local_storage_free(local_storage, storage_smap, bpf_ma, reuse_now);
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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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static 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 reuse_now)
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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, reuse_now);
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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))
|
|
rcu_assign_pointer(local_storage->cache[smap->cache_idx],
|
|
sdata);
|
|
raw_spin_unlock_irqrestore(&local_storage->lock, flags);
|
|
}
|
|
|
|
return sdata;
|
|
}
|
|
|
|
static int check_flags(const struct bpf_local_storage_data *old_sdata,
|
|
u64 map_flags)
|
|
{
|
|
if (old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST)
|
|
/* elem already exists */
|
|
return -EEXIST;
|
|
|
|
if (!old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_EXIST)
|
|
/* elem doesn't exist, cannot update it */
|
|
return -ENOENT;
|
|
|
|
return 0;
|
|
}
|
|
|
|
int bpf_local_storage_alloc(void *owner,
|
|
struct bpf_local_storage_map *smap,
|
|
struct bpf_local_storage_elem *first_selem,
|
|
gfp_t gfp_flags)
|
|
{
|
|
struct bpf_local_storage *prev_storage, *storage;
|
|
struct bpf_local_storage **owner_storage_ptr;
|
|
int err;
|
|
|
|
err = mem_charge(smap, owner, sizeof(*storage));
|
|
if (err)
|
|
return err;
|
|
|
|
if (smap->bpf_ma) {
|
|
migrate_disable();
|
|
storage = bpf_mem_cache_alloc_flags(&smap->storage_ma, gfp_flags);
|
|
migrate_enable();
|
|
} else {
|
|
storage = bpf_map_kzalloc(&smap->map, sizeof(*storage),
|
|
gfp_flags | __GFP_NOWARN);
|
|
}
|
|
|
|
if (!storage) {
|
|
err = -ENOMEM;
|
|
goto uncharge;
|
|
}
|
|
|
|
RCU_INIT_POINTER(storage->smap, smap);
|
|
INIT_HLIST_HEAD(&storage->list);
|
|
raw_spin_lock_init(&storage->lock);
|
|
storage->owner = owner;
|
|
|
|
bpf_selem_link_storage_nolock(storage, first_selem);
|
|
bpf_selem_link_map(smap, first_selem);
|
|
|
|
owner_storage_ptr =
|
|
(struct bpf_local_storage **)owner_storage(smap, owner);
|
|
/* Publish storage to the owner.
|
|
* Instead of using any lock of the kernel object (i.e. owner),
|
|
* cmpxchg will work with any kernel object regardless what
|
|
* the running context is, bh, irq...etc.
|
|
*
|
|
* From now on, the owner->storage pointer (e.g. sk->sk_bpf_storage)
|
|
* is protected by the storage->lock. Hence, when freeing
|
|
* the owner->storage, the storage->lock must be held before
|
|
* setting owner->storage ptr to NULL.
|
|
*/
|
|
prev_storage = cmpxchg(owner_storage_ptr, NULL, storage);
|
|
if (unlikely(prev_storage)) {
|
|
bpf_selem_unlink_map(first_selem);
|
|
err = -EAGAIN;
|
|
goto uncharge;
|
|
|
|
/* Note that even first_selem was linked to smap's
|
|
* bucket->list, first_selem can be freed immediately
|
|
* (instead of kfree_rcu) because
|
|
* bpf_local_storage_map_free() does a
|
|
* synchronize_rcu_mult (waiting for both sleepable and
|
|
* normal programs) before walking the bucket->list.
|
|
* Hence, no one is accessing selem from the
|
|
* bucket->list under rcu_read_lock().
|
|
*/
|
|
}
|
|
|
|
return 0;
|
|
|
|
uncharge:
|
|
bpf_local_storage_free(storage, smap, smap->bpf_ma, true);
|
|
mem_uncharge(smap, owner, sizeof(*storage));
|
|
return err;
|
|
}
|
|
|
|
/* sk cannot be going away because it is linking new elem
|
|
* to sk->sk_bpf_storage. (i.e. sk->sk_refcnt cannot be 0).
|
|
* Otherwise, it will become a leak (and other memory issues
|
|
* during map destruction).
|
|
*/
|
|
struct bpf_local_storage_data *
|
|
bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
|
|
void *value, u64 map_flags, gfp_t gfp_flags)
|
|
{
|
|
struct bpf_local_storage_data *old_sdata = NULL;
|
|
struct bpf_local_storage_elem *alloc_selem, *selem = NULL;
|
|
struct bpf_local_storage *local_storage;
|
|
unsigned long flags;
|
|
int err;
|
|
|
|
/* BPF_EXIST and BPF_NOEXIST cannot be both set */
|
|
if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST) ||
|
|
/* BPF_F_LOCK can only be used in a value with spin_lock */
|
|
unlikely((map_flags & BPF_F_LOCK) &&
|
|
!btf_record_has_field(smap->map.record, BPF_SPIN_LOCK)))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
if (gfp_flags == GFP_KERNEL && (map_flags & ~BPF_F_LOCK) != BPF_NOEXIST)
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
local_storage = rcu_dereference_check(*owner_storage(smap, owner),
|
|
bpf_rcu_lock_held());
|
|
if (!local_storage || hlist_empty(&local_storage->list)) {
|
|
/* Very first elem for the owner */
|
|
err = check_flags(NULL, map_flags);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
selem = bpf_selem_alloc(smap, owner, value, true, gfp_flags);
|
|
if (!selem)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
err = bpf_local_storage_alloc(owner, smap, selem, gfp_flags);
|
|
if (err) {
|
|
bpf_selem_free(selem, smap, true);
|
|
mem_uncharge(smap, owner, smap->elem_size);
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
return SDATA(selem);
|
|
}
|
|
|
|
if ((map_flags & BPF_F_LOCK) && !(map_flags & BPF_NOEXIST)) {
|
|
/* Hoping to find an old_sdata to do inline update
|
|
* such that it can avoid taking the local_storage->lock
|
|
* and changing the lists.
|
|
*/
|
|
old_sdata =
|
|
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;
|
|
}
|
|
}
|
|
|
|
/* A lookup has just been done before and concluded a new selem is
|
|
* needed. The chance of an unnecessary alloc is unlikely.
|
|
*/
|
|
alloc_selem = selem = bpf_selem_alloc(smap, owner, value, true, gfp_flags);
|
|
if (!alloc_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;
|
|
}
|
|
|
|
old_sdata = bpf_local_storage_lookup(local_storage, smap, false);
|
|
err = check_flags(old_sdata, map_flags);
|
|
if (err)
|
|
goto unlock;
|
|
|
|
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;
|
|
}
|
|
|
|
alloc_selem = NULL;
|
|
/* 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),
|
|
true, false);
|
|
}
|
|
|
|
unlock:
|
|
raw_spin_unlock_irqrestore(&local_storage->lock, flags);
|
|
if (alloc_selem) {
|
|
mem_uncharge(smap, owner, smap->elem_size);
|
|
bpf_selem_free(alloc_selem, smap, true);
|
|
}
|
|
return err ? ERR_PTR(err) : SDATA(selem);
|
|
}
|
|
|
|
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 (attr->value_size > BPF_LOCAL_STORAGE_MAX_VALUE_SIZE)
|
|
return -E2BIG;
|
|
|
|
return 0;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
void bpf_local_storage_destroy(struct bpf_local_storage *local_storage)
|
|
{
|
|
struct bpf_local_storage_map *storage_smap;
|
|
struct bpf_local_storage_elem *selem;
|
|
bool bpf_ma, free_storage = false;
|
|
struct hlist_node *n;
|
|
unsigned long flags;
|
|
|
|
storage_smap = rcu_dereference_check(local_storage->smap, bpf_rcu_lock_held());
|
|
bpf_ma = check_storage_bpf_ma(local_storage, storage_smap, NULL);
|
|
|
|
/* 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.
|
|
*/
|
|
raw_spin_lock_irqsave(&local_storage->lock, flags);
|
|
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, true, true);
|
|
}
|
|
raw_spin_unlock_irqrestore(&local_storage->lock, flags);
|
|
|
|
if (free_storage)
|
|
bpf_local_storage_free(local_storage, storage_smap, bpf_ma, true);
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
/* When bpf_ma == true, the bpf_mem_alloc is used to allocate and free memory.
|
|
* A deadlock free allocator is useful for storage that the bpf prog can easily
|
|
* get a hold of the owner PTR_TO_BTF_ID in any context. eg. bpf_get_current_task_btf.
|
|
* The task and cgroup storage fall into this case. The bpf_mem_alloc reuses
|
|
* memory immediately. To be reuse-immediate safe, the owner destruction
|
|
* code path needs to go through a rcu grace period before calling
|
|
* bpf_local_storage_destroy().
|
|
*
|
|
* When bpf_ma == false, the kmalloc and kfree are used.
|
|
*/
|
|
struct bpf_map *
|
|
bpf_local_storage_map_alloc(union bpf_attr *attr,
|
|
struct bpf_local_storage_cache *cache,
|
|
bool bpf_ma)
|
|
{
|
|
struct bpf_local_storage_map *smap;
|
|
unsigned int i;
|
|
u32 nbuckets;
|
|
int err;
|
|
|
|
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) {
|
|
err = -ENOMEM;
|
|
goto free_smap;
|
|
}
|
|
|
|
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]);
|
|
|
|
smap->bpf_ma = bpf_ma;
|
|
if (bpf_ma) {
|
|
err = bpf_mem_alloc_init(&smap->selem_ma, smap->elem_size, false);
|
|
if (err)
|
|
goto free_smap;
|
|
|
|
err = bpf_mem_alloc_init(&smap->storage_ma, sizeof(struct bpf_local_storage), false);
|
|
if (err) {
|
|
bpf_mem_alloc_destroy(&smap->selem_ma);
|
|
goto free_smap;
|
|
}
|
|
}
|
|
|
|
smap->cache_idx = bpf_local_storage_cache_idx_get(cache);
|
|
return &smap->map;
|
|
|
|
free_smap:
|
|
kvfree(smap->buckets);
|
|
bpf_map_area_free(smap);
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
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, true);
|
|
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();
|
|
|
|
if (smap->bpf_ma) {
|
|
bpf_mem_alloc_destroy(&smap->selem_ma);
|
|
bpf_mem_alloc_destroy(&smap->storage_ma);
|
|
}
|
|
kvfree(smap->buckets);
|
|
bpf_map_area_free(smap);
|
|
}
|