Enable support for kptrs in local storage maps by wiring up the freeing
of these kptrs from map value.
Cc: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
Cc: KP Singh <kpsingh@xxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
---
kernel/bpf/bpf_local_storage.c | 35 ++++++++++++++++++++++++++++++----
kernel/bpf/syscall.c | 6 +++++-
kernel/bpf/verifier.c | 12 ++++++++----
3 files changed, 44 insertions(+), 9 deletions(-)
diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c
index 35f4138a54dc..4521d53d7d4d 100644
--- a/kernel/bpf/bpf_local_storage.c
+++ b/kernel/bpf/bpf_local_storage.c
@@ -75,6 +75,7 @@ bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner,
if (selem) {
if (value)
copy_map_value(&smap->map, SDATA(selem)->data, value);
+ /* No need to call check_and_init_map_value as memory is zero init */
return selem;
}
@@ -103,10 +104,17 @@ static void bpf_selem_free_rcu(struct rcu_head *rcu)
struct bpf_local_storage_elem *selem;
selem = container_of(rcu, struct bpf_local_storage_elem, rcu);
+ bpf_obj_free_fields(SDATA(selem)->smap->map.record, SDATA(selem));
+ kfree(selem);
+}
+
+static void bpf_selem_free_tasks_trace_rcu(struct rcu_head *rcu)
+{
+ /* Free directly if Tasks Trace RCU GP also implies RCU GP */
if (rcu_trace_implies_rcu_gp())
- kfree(selem);
+ bpf_selem_free_rcu(rcu);
else
- kfree_rcu(selem, rcu);
+ call_rcu(rcu, bpf_selem_free_rcu);
}
/* local_storage->lock must be held and selem->local_storage == local_storage.
@@ -160,9 +168,9 @@ static bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_stor
RCU_INIT_POINTER(local_storage->cache[smap->cache_idx], NULL);
if (use_trace_rcu)
- call_rcu_tasks_trace(&selem->rcu, bpf_selem_free_rcu);
+ call_rcu_tasks_trace(&selem->rcu, bpf_selem_free_tasks_trace_rcu);
else
- kfree_rcu(selem, rcu);
+ call_rcu(&selem->rcu, bpf_selem_free_rcu);
return free_local_storage;
}
@@ -713,6 +721,25 @@ void bpf_local_storage_map_free(struct bpf_map *map,
*/
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_rcu and bpf_selem_free_tasks_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_tasks_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 earlier while
+ * ((selem = ...)) loop or from bpf_local_storage_unlink_nolock
+ * called from owner's free path.
+ */
+ rcu_barrier();
+ }
bpf_map_area_free(smap);
}
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index da117a2a83b2..eb50025b03c1 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1063,7 +1063,11 @@ static int map_check_btf(struct bpf_map *map, const struct btf *btf,
map->map_type != BPF_MAP_TYPE_LRU_HASH &&
map->map_type != BPF_MAP_TYPE_LRU_PERCPU_HASH &&
map->map_type != BPF_MAP_TYPE_ARRAY &&
- map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY) {
+ map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY &&
+ map->map_type != BPF_MAP_TYPE_SK_STORAGE &&
+ map->map_type != BPF_MAP_TYPE_INODE_STORAGE &&
+ map->map_type != BPF_MAP_TYPE_TASK_STORAGE &&
+ map->map_type != BPF_MAP_TYPE_CGRP_STORAGE) {
ret = -EOPNOTSUPP;
goto free_map_tab;
}
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 272563a0b770..9a4e7efaf28f 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7126,22 +7126,26 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
break;
case BPF_MAP_TYPE_SK_STORAGE:
if (func_id != BPF_FUNC_sk_storage_get &&
- func_id != BPF_FUNC_sk_storage_delete)
+ func_id != BPF_FUNC_sk_storage_delete &&
+ func_id != BPF_FUNC_kptr_xchg)
goto error;
break;
case BPF_MAP_TYPE_INODE_STORAGE:
if (func_id != BPF_FUNC_inode_storage_get &&
- func_id != BPF_FUNC_inode_storage_delete)
+ func_id != BPF_FUNC_inode_storage_delete &&
+ func_id != BPF_FUNC_kptr_xchg)
goto error;
break;
case BPF_MAP_TYPE_TASK_STORAGE:
if (func_id != BPF_FUNC_task_storage_get &&
- func_id != BPF_FUNC_task_storage_delete)
+ func_id != BPF_FUNC_task_storage_delete &&
+ func_id != BPF_FUNC_kptr_xchg)
goto error;
break;
case BPF_MAP_TYPE_CGRP_STORAGE:
if (func_id != BPF_FUNC_cgrp_storage_get &&
- func_id != BPF_FUNC_cgrp_storage_delete)
+ func_id != BPF_FUNC_cgrp_storage_delete &&
+ func_id != BPF_FUNC_kptr_xchg)
goto error;
break;
case BPF_MAP_TYPE_BLOOM_FILTER:
--
2.39.2
