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Message-ID: <20200713161747.3077347-1-yhs@fb.com>
Date: Mon, 13 Jul 2020 09:17:47 -0700
From: Yonghong Song <yhs@...com>
To: <bpf@...r.kernel.org>, <netdev@...r.kernel.org>
CC: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>, <kernel-team@...com>,
Martin KaFai Lau <kafai@...com>
Subject: [PATCH bpf-next 07/13] bpf: implement bpf iterator for sock local storage map
The bpf iterator for bpf sock local storage map
is implemented. User space interacts with sock
local storage map with fd as a key and storage value.
In kernel, passing fd to the bpf program does not
really make sense. In this case, the sock itself is
passed to bpf program.
Signed-off-by: Yonghong Song <yhs@...com>
---
net/core/bpf_sk_storage.c | 203 ++++++++++++++++++++++++++++++++++++++
1 file changed, 203 insertions(+)
diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c
index 6f921c4ddc2c..95638eca5d67 100644
--- a/net/core/bpf_sk_storage.c
+++ b/net/core/bpf_sk_storage.c
@@ -1217,3 +1217,206 @@ int bpf_sk_storage_diag_put(struct bpf_sk_storage_diag *diag,
return err;
}
EXPORT_SYMBOL_GPL(bpf_sk_storage_diag_put);
+
+struct bpf_iter_seq_sk_storage_map_info {
+ struct bpf_map *map;
+ unsigned int bucket_id;
+ unsigned skip_elems;
+};
+
+static struct bpf_sk_storage_elem *
+bpf_sk_storage_map_seq_find_next(struct bpf_iter_seq_sk_storage_map_info *info,
+ struct bpf_sk_storage_elem *prev_selem)
+{
+ struct bpf_sk_storage *sk_storage;
+ struct bpf_sk_storage_elem *selem;
+ u32 skip_elems = info->skip_elems;
+ struct bpf_sk_storage_map *smap;
+ u32 bucket_id = info->bucket_id;
+ u32 i, count, n_buckets;
+ struct bucket *b;
+
+ smap = (struct bpf_sk_storage_map *)info->map;
+ n_buckets = 1U << smap->bucket_log;
+ if (bucket_id >= n_buckets)
+ return NULL;
+
+ /* try to find next selem in the same bucket */
+ selem = prev_selem;
+ count = 0;
+ while (selem) {
+ selem = hlist_entry_safe(selem->map_node.next,
+ struct bpf_sk_storage_elem, map_node);
+ if (!selem) {
+ /* not found, unlock and go to the next bucket */
+ b = &smap->buckets[bucket_id++];
+ raw_spin_unlock_bh(&b->lock);
+ skip_elems = 0;
+ break;
+ }
+ sk_storage = rcu_dereference_raw(selem->sk_storage);
+ if (sk_storage) {
+ info->skip_elems = skip_elems + count;
+ return selem;
+ }
+ count++;
+ }
+
+ for (i = bucket_id; i < (1U << smap->bucket_log); i++) {
+ b = &smap->buckets[i];
+ raw_spin_lock_bh(&b->lock);
+ count = 0;
+ hlist_for_each_entry(selem, &b->list, map_node) {
+ sk_storage = rcu_dereference_raw(selem->sk_storage);
+ if (sk_storage && count >= skip_elems) {
+ info->bucket_id = i;
+ info->skip_elems = count;
+ return selem;
+ }
+ count++;
+ }
+ raw_spin_unlock_bh(&b->lock);
+ skip_elems = 0;
+ }
+
+ info->bucket_id = i;
+ info->skip_elems = 0;
+ return NULL;
+}
+
+static void *bpf_sk_storage_map_seq_start(struct seq_file *seq, loff_t *pos)
+{
+ struct bpf_sk_storage_elem *selem;
+
+ selem = bpf_sk_storage_map_seq_find_next(seq->private, NULL);
+ if (!selem)
+ return NULL;
+
+ if (*pos == 0)
+ ++*pos;
+ return selem;
+}
+
+static void *bpf_sk_storage_map_seq_next(struct seq_file *seq, void *v,
+ loff_t *pos)
+{
+ struct bpf_iter_seq_sk_storage_map_info *info = seq->private;
+
+ ++*pos;
+ ++info->skip_elems;
+ return bpf_sk_storage_map_seq_find_next(seq->private, v);
+}
+
+struct bpf_iter__bpf_sk_storage_map {
+ __bpf_md_ptr(struct bpf_iter_meta *, meta);
+ __bpf_md_ptr(struct bpf_map *, map);
+ __bpf_md_ptr(struct sock *, sk);
+ __bpf_md_ptr(void *, value);
+};
+
+DEFINE_BPF_ITER_FUNC(bpf_sk_storage_map, struct bpf_iter_meta *meta,
+ struct bpf_map *map, struct sock *sk,
+ void *value)
+
+static int __bpf_sk_storage_map_seq_show(struct seq_file *seq,
+ struct bpf_sk_storage_elem *selem)
+{
+ struct bpf_iter_seq_sk_storage_map_info *info = seq->private;
+ struct bpf_iter__bpf_sk_storage_map ctx = {};
+ struct bpf_sk_storage *sk_storage;
+ struct bpf_iter_meta meta;
+ struct bpf_prog *prog;
+ int ret = 0;
+
+ meta.seq = seq;
+ prog = bpf_iter_get_info(&meta, selem == NULL);
+ if (prog) {
+ ctx.meta = &meta;
+ ctx.map = info->map;
+ if (selem) {
+ sk_storage = rcu_dereference_raw(selem->sk_storage);
+ ctx.sk = sk_storage->sk;
+ ctx.value = SDATA(selem)->data;
+ }
+ ret = bpf_iter_run_prog(prog, &ctx);
+ }
+
+ return ret;
+}
+
+static int bpf_sk_storage_map_seq_show(struct seq_file *seq, void *v)
+{
+ return __bpf_sk_storage_map_seq_show(seq, v);
+}
+
+static void bpf_sk_storage_map_seq_stop(struct seq_file *seq, void *v)
+{
+ struct bpf_iter_seq_sk_storage_map_info *info = seq->private;
+ struct bpf_sk_storage_map *smap;
+ struct bucket *b;
+
+ if (!v) {
+ (void)__bpf_sk_storage_map_seq_show(seq, v);
+ } else {
+ smap = (struct bpf_sk_storage_map *)info->map;
+ b = &smap->buckets[info->bucket_id];
+ raw_spin_unlock_bh(&b->lock);
+ }
+}
+
+static int bpf_iter_init_sk_storage_map(void *priv_data,
+ struct bpf_iter_aux_info *aux)
+{
+ struct bpf_iter_seq_sk_storage_map_info *seq_info = priv_data;
+
+ seq_info->map = aux->map;
+ return 0;
+}
+
+static int bpf_iter_check_map(struct bpf_prog *prog,
+ struct bpf_iter_aux_info *aux)
+{
+ struct bpf_map *map = aux->map;
+
+ if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
+ return -EINVAL;
+
+ if (prog->aux->max_rdonly_access[0] > map->value_size)
+ return -EACCES;
+
+ return 0;
+}
+
+static const struct seq_operations bpf_sk_storage_map_seq_ops = {
+ .start = bpf_sk_storage_map_seq_start,
+ .next = bpf_sk_storage_map_seq_next,
+ .stop = bpf_sk_storage_map_seq_stop,
+ .show = bpf_sk_storage_map_seq_show,
+};
+
+static const struct bpf_iter_seq_info iter_seq_info = {
+ .seq_ops = &bpf_sk_storage_map_seq_ops,
+ .init_seq_private = bpf_iter_init_sk_storage_map,
+ .fini_seq_private = NULL,
+ .seq_priv_size = sizeof(struct bpf_iter_seq_sk_storage_map_info),
+};
+
+static const struct bpf_iter_reg bpf_sk_storage_map_reg_info = {
+ .target = "bpf_sk_storage_map",
+ .check_target = bpf_iter_check_map,
+ .link_info = BPF_ITER_LINK_MAP_FD,
+ .ctx_arg_info_size = 2,
+ .ctx_arg_info = {
+ { offsetof(struct bpf_iter__bpf_sk_storage_map, sk),
+ PTR_TO_BTF_ID_OR_NULL },
+ { offsetof(struct bpf_iter__bpf_sk_storage_map, value),
+ PTR_TO_RDONLY_BUF_OR_NULL },
+ },
+ .seq_info = &iter_seq_info,
+};
+
+static int __init bpf_sk_storage_map_iter_init(void)
+{
+ return bpf_iter_reg_target(&bpf_sk_storage_map_reg_info);
+}
+late_initcall(bpf_sk_storage_map_iter_init);
--
2.24.1
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