net: Allow iterating sockmap and sockhash
Add bpf_iter support for sockmap / sockhash, based on the bpf_sk_storage and hashtable implementation. sockmap and sockhash share the same iteration context: a pointer to an arbitrary key and a pointer to a socket. Both pointers may be NULL, and so BPF has to perform a NULL check before accessing them. Technically it's not possible for sockhash iteration to yield a NULL socket, but we ignore this to be able to use a single iteration point. Iteration will visit all keys that remain unmodified during the lifetime of the iterator. It may or may not visit newly added ones. Switch from using rcu_dereference_raw to plain rcu_dereference, so we gain another guard rail if CONFIG_PROVE_RCU is enabled. Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200909162712.221874-3-lmb@cloudflare.com
This commit is contained in:
Lorenz Bauer
Alexei Starovoitov
Родитель
654785a1af
Коммит
0365351524
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@ -2,6 +2,7 @@
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/* Copyright (c) 2017 - 2018 Covalent IO, Inc. http://covalent.io */
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#include <linux/bpf.h>
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#include <linux/btf_ids.h>
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#include <linux/filter.h>
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#include <linux/errno.h>
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#include <linux/file.h>
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@ -703,6 +704,109 @@ const struct bpf_func_proto bpf_msg_redirect_map_proto = {
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.arg4_type = ARG_ANYTHING,
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};
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struct sock_map_seq_info {
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struct bpf_map *map;
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struct sock *sk;
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u32 index;
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};
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struct bpf_iter__sockmap {
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__bpf_md_ptr(struct bpf_iter_meta *, meta);
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__bpf_md_ptr(struct bpf_map *, map);
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__bpf_md_ptr(void *, key);
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__bpf_md_ptr(struct sock *, sk);
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};
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DEFINE_BPF_ITER_FUNC(sockmap, struct bpf_iter_meta *meta,
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struct bpf_map *map, void *key,
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struct sock *sk)
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static void *sock_map_seq_lookup_elem(struct sock_map_seq_info *info)
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{
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if (unlikely(info->index >= info->map->max_entries))
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return NULL;
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info->sk = __sock_map_lookup_elem(info->map, info->index);
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/* can't return sk directly, since that might be NULL */
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return info;
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}
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static void *sock_map_seq_start(struct seq_file *seq, loff_t *pos)
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{
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struct sock_map_seq_info *info = seq->private;
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if (*pos == 0)
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++*pos;
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/* pairs with sock_map_seq_stop */
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rcu_read_lock();
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return sock_map_seq_lookup_elem(info);
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}
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static void *sock_map_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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struct sock_map_seq_info *info = seq->private;
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++*pos;
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++info->index;
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return sock_map_seq_lookup_elem(info);
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}
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static int sock_map_seq_show(struct seq_file *seq, void *v)
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{
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struct sock_map_seq_info *info = seq->private;
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struct bpf_iter__sockmap ctx = {};
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struct bpf_iter_meta meta;
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struct bpf_prog *prog;
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meta.seq = seq;
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prog = bpf_iter_get_info(&meta, !v);
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if (!prog)
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return 0;
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ctx.meta = &meta;
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ctx.map = info->map;
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if (v) {
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ctx.key = &info->index;
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ctx.sk = info->sk;
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}
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return bpf_iter_run_prog(prog, &ctx);
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}
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static void sock_map_seq_stop(struct seq_file *seq, void *v)
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{
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if (!v)
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(void)sock_map_seq_show(seq, NULL);
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/* pairs with sock_map_seq_start */
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rcu_read_unlock();
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}
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static const struct seq_operations sock_map_seq_ops = {
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.start = sock_map_seq_start,
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.next = sock_map_seq_next,
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.stop = sock_map_seq_stop,
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.show = sock_map_seq_show,
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};
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static int sock_map_init_seq_private(void *priv_data,
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struct bpf_iter_aux_info *aux)
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{
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struct sock_map_seq_info *info = priv_data;
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info->map = aux->map;
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return 0;
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}
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static const struct bpf_iter_seq_info sock_map_iter_seq_info = {
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.seq_ops = &sock_map_seq_ops,
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.init_seq_private = sock_map_init_seq_private,
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.seq_priv_size = sizeof(struct sock_map_seq_info),
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};
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static int sock_map_btf_id;
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const struct bpf_map_ops sock_map_ops = {
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.map_meta_equal = bpf_map_meta_equal,
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@ -717,6 +821,7 @@ const struct bpf_map_ops sock_map_ops = {
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.map_check_btf = map_check_no_btf,
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.map_btf_name = "bpf_stab",
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.map_btf_id = &sock_map_btf_id,
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.iter_seq_info = &sock_map_iter_seq_info,
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};
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struct bpf_shtab_elem {
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@ -953,7 +1058,7 @@ static int sock_hash_get_next_key(struct bpf_map *map, void *key,
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if (!elem)
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goto find_first_elem;
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elem_next = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&elem->node)),
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elem_next = hlist_entry_safe(rcu_dereference(hlist_next_rcu(&elem->node)),
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struct bpf_shtab_elem, node);
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if (elem_next) {
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memcpy(key_next, elem_next->key, key_size);
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@ -965,7 +1070,7 @@ static int sock_hash_get_next_key(struct bpf_map *map, void *key,
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find_first_elem:
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for (; i < htab->buckets_num; i++) {
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head = &sock_hash_select_bucket(htab, i)->head;
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elem_next = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
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elem_next = hlist_entry_safe(rcu_dereference(hlist_first_rcu(head)),
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struct bpf_shtab_elem, node);
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if (elem_next) {
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memcpy(key_next, elem_next->key, key_size);
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@ -1199,6 +1304,117 @@ const struct bpf_func_proto bpf_msg_redirect_hash_proto = {
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.arg4_type = ARG_ANYTHING,
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};
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struct sock_hash_seq_info {
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struct bpf_map *map;
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struct bpf_shtab *htab;
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u32 bucket_id;
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};
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static void *sock_hash_seq_find_next(struct sock_hash_seq_info *info,
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struct bpf_shtab_elem *prev_elem)
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{
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const struct bpf_shtab *htab = info->htab;
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struct bpf_shtab_bucket *bucket;
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struct bpf_shtab_elem *elem;
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struct hlist_node *node;
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/* try to find next elem in the same bucket */
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if (prev_elem) {
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node = rcu_dereference(hlist_next_rcu(&prev_elem->node));
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elem = hlist_entry_safe(node, struct bpf_shtab_elem, node);
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if (elem)
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return elem;
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/* no more elements, continue in the next bucket */
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info->bucket_id++;
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}
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for (; info->bucket_id < htab->buckets_num; info->bucket_id++) {
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bucket = &htab->buckets[info->bucket_id];
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node = rcu_dereference(hlist_first_rcu(&bucket->head));
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elem = hlist_entry_safe(node, struct bpf_shtab_elem, node);
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if (elem)
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return elem;
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}
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return NULL;
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}
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static void *sock_hash_seq_start(struct seq_file *seq, loff_t *pos)
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{
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struct sock_hash_seq_info *info = seq->private;
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if (*pos == 0)
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++*pos;
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/* pairs with sock_hash_seq_stop */
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rcu_read_lock();
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return sock_hash_seq_find_next(info, NULL);
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}
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static void *sock_hash_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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struct sock_hash_seq_info *info = seq->private;
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++*pos;
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return sock_hash_seq_find_next(info, v);
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}
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static int sock_hash_seq_show(struct seq_file *seq, void *v)
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{
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struct sock_hash_seq_info *info = seq->private;
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struct bpf_iter__sockmap ctx = {};
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struct bpf_shtab_elem *elem = v;
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struct bpf_iter_meta meta;
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struct bpf_prog *prog;
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meta.seq = seq;
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prog = bpf_iter_get_info(&meta, !elem);
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if (!prog)
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return 0;
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ctx.meta = &meta;
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ctx.map = info->map;
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if (elem) {
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ctx.key = elem->key;
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ctx.sk = elem->sk;
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}
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return bpf_iter_run_prog(prog, &ctx);
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}
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static void sock_hash_seq_stop(struct seq_file *seq, void *v)
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{
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if (!v)
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(void)sock_hash_seq_show(seq, NULL);
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/* pairs with sock_hash_seq_start */
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rcu_read_unlock();
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}
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static const struct seq_operations sock_hash_seq_ops = {
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.start = sock_hash_seq_start,
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.next = sock_hash_seq_next,
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.stop = sock_hash_seq_stop,
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.show = sock_hash_seq_show,
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};
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static int sock_hash_init_seq_private(void *priv_data,
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struct bpf_iter_aux_info *aux)
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{
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struct sock_hash_seq_info *info = priv_data;
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info->map = aux->map;
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info->htab = container_of(aux->map, struct bpf_shtab, map);
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return 0;
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}
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static const struct bpf_iter_seq_info sock_hash_iter_seq_info = {
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.seq_ops = &sock_hash_seq_ops,
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.init_seq_private = sock_hash_init_seq_private,
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.seq_priv_size = sizeof(struct sock_hash_seq_info),
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};
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static int sock_hash_map_btf_id;
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const struct bpf_map_ops sock_hash_ops = {
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.map_meta_equal = bpf_map_meta_equal,
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@ -1213,6 +1429,7 @@ const struct bpf_map_ops sock_hash_ops = {
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.map_check_btf = map_check_no_btf,
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.map_btf_name = "bpf_shtab",
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.map_btf_id = &sock_hash_map_btf_id,
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.iter_seq_info = &sock_hash_iter_seq_info,
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};
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static struct sk_psock_progs *sock_map_progs(struct bpf_map *map)
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@ -1323,3 +1540,62 @@ void sock_map_close(struct sock *sk, long timeout)
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release_sock(sk);
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saved_close(sk, timeout);
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}
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static int sock_map_iter_attach_target(struct bpf_prog *prog,
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union bpf_iter_link_info *linfo,
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struct bpf_iter_aux_info *aux)
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{
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struct bpf_map *map;
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int err = -EINVAL;
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if (!linfo->map.map_fd)
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return -EBADF;
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map = bpf_map_get_with_uref(linfo->map.map_fd);
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if (IS_ERR(map))
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return PTR_ERR(map);
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if (map->map_type != BPF_MAP_TYPE_SOCKMAP &&
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map->map_type != BPF_MAP_TYPE_SOCKHASH)
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goto put_map;
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if (prog->aux->max_rdonly_access > map->key_size) {
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err = -EACCES;
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goto put_map;
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}
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aux->map = map;
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return 0;
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put_map:
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bpf_map_put_with_uref(map);
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return err;
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}
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static void sock_map_iter_detach_target(struct bpf_iter_aux_info *aux)
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{
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bpf_map_put_with_uref(aux->map);
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}
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static struct bpf_iter_reg sock_map_iter_reg = {
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.target = "sockmap",
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.attach_target = sock_map_iter_attach_target,
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.detach_target = sock_map_iter_detach_target,
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.show_fdinfo = bpf_iter_map_show_fdinfo,
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.fill_link_info = bpf_iter_map_fill_link_info,
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.ctx_arg_info_size = 2,
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.ctx_arg_info = {
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{ offsetof(struct bpf_iter__sockmap, key),
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PTR_TO_RDONLY_BUF_OR_NULL },
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{ offsetof(struct bpf_iter__sockmap, sk),
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PTR_TO_BTF_ID_OR_NULL },
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},
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};
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static int __init bpf_sockmap_iter_init(void)
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{
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sock_map_iter_reg.ctx_arg_info[1].btf_id =
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btf_sock_ids[BTF_SOCK_TYPE_SOCK];
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return bpf_iter_reg_target(&sock_map_iter_reg);
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}
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late_initcall(bpf_sockmap_iter_init);
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