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@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200723184116.590602-1-yhs@fb.com
This commit is contained in:
Yonghong Song
Alexei Starovoitov
parent
d3cc2ab546
commit
5ce6e77c7e
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@ -6,6 +6,7 @@
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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 <net/bpf_sk_storage.h>
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#include <net/sock.h>
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#include <uapi/linux/sock_diag.h>
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@ -1217,3 +1218,208 @@ int bpf_sk_storage_diag_put(struct bpf_sk_storage_diag *diag,
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return err;
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}
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EXPORT_SYMBOL_GPL(bpf_sk_storage_diag_put);
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struct bpf_iter_seq_sk_storage_map_info {
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struct bpf_map *map;
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unsigned int bucket_id;
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unsigned skip_elems;
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};
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static struct bpf_sk_storage_elem *
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bpf_sk_storage_map_seq_find_next(struct bpf_iter_seq_sk_storage_map_info *info,
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struct bpf_sk_storage_elem *prev_selem)
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{
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struct bpf_sk_storage *sk_storage;
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struct bpf_sk_storage_elem *selem;
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u32 skip_elems = info->skip_elems;
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struct bpf_sk_storage_map *smap;
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u32 bucket_id = info->bucket_id;
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u32 i, count, n_buckets;
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struct bucket *b;
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smap = (struct bpf_sk_storage_map *)info->map;
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n_buckets = 1U << smap->bucket_log;
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if (bucket_id >= n_buckets)
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return NULL;
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/* try to find next selem in the same bucket */
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selem = prev_selem;
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count = 0;
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while (selem) {
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selem = hlist_entry_safe(selem->map_node.next,
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struct bpf_sk_storage_elem, map_node);
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if (!selem) {
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/* not found, unlock and go to the next bucket */
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b = &smap->buckets[bucket_id++];
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raw_spin_unlock_bh(&b->lock);
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skip_elems = 0;
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break;
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}
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sk_storage = rcu_dereference_raw(selem->sk_storage);
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if (sk_storage) {
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info->skip_elems = skip_elems + count;
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return selem;
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}
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count++;
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}
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for (i = bucket_id; i < (1U << smap->bucket_log); i++) {
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b = &smap->buckets[i];
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raw_spin_lock_bh(&b->lock);
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count = 0;
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hlist_for_each_entry(selem, &b->list, map_node) {
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sk_storage = rcu_dereference_raw(selem->sk_storage);
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if (sk_storage && count >= skip_elems) {
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info->bucket_id = i;
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info->skip_elems = count;
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return selem;
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}
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count++;
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}
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raw_spin_unlock_bh(&b->lock);
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skip_elems = 0;
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}
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info->bucket_id = i;
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info->skip_elems = 0;
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return NULL;
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}
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static void *bpf_sk_storage_map_seq_start(struct seq_file *seq, loff_t *pos)
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{
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struct bpf_sk_storage_elem *selem;
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selem = bpf_sk_storage_map_seq_find_next(seq->private, NULL);
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if (!selem)
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return NULL;
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if (*pos == 0)
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++*pos;
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return selem;
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}
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static void *bpf_sk_storage_map_seq_next(struct seq_file *seq, void *v,
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loff_t *pos)
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{
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struct bpf_iter_seq_sk_storage_map_info *info = seq->private;
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++*pos;
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++info->skip_elems;
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return bpf_sk_storage_map_seq_find_next(seq->private, v);
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}
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struct bpf_iter__bpf_sk_storage_map {
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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(struct sock *, sk);
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__bpf_md_ptr(void *, value);
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};
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DEFINE_BPF_ITER_FUNC(bpf_sk_storage_map, struct bpf_iter_meta *meta,
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struct bpf_map *map, struct sock *sk,
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void *value)
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static int __bpf_sk_storage_map_seq_show(struct seq_file *seq,
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struct bpf_sk_storage_elem *selem)
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{
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struct bpf_iter_seq_sk_storage_map_info *info = seq->private;
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struct bpf_iter__bpf_sk_storage_map ctx = {};
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struct bpf_sk_storage *sk_storage;
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struct bpf_iter_meta meta;
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struct bpf_prog *prog;
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int ret = 0;
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meta.seq = seq;
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prog = bpf_iter_get_info(&meta, selem == NULL);
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if (prog) {
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ctx.meta = &meta;
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ctx.map = info->map;
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if (selem) {
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sk_storage = rcu_dereference_raw(selem->sk_storage);
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ctx.sk = sk_storage->sk;
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ctx.value = SDATA(selem)->data;
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}
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ret = bpf_iter_run_prog(prog, &ctx);
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}
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return ret;
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}
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static int bpf_sk_storage_map_seq_show(struct seq_file *seq, void *v)
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{
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return __bpf_sk_storage_map_seq_show(seq, v);
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}
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static void bpf_sk_storage_map_seq_stop(struct seq_file *seq, void *v)
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{
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struct bpf_iter_seq_sk_storage_map_info *info = seq->private;
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struct bpf_sk_storage_map *smap;
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struct bucket *b;
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if (!v) {
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(void)__bpf_sk_storage_map_seq_show(seq, v);
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} else {
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smap = (struct bpf_sk_storage_map *)info->map;
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b = &smap->buckets[info->bucket_id];
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raw_spin_unlock_bh(&b->lock);
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}
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}
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static int bpf_iter_init_sk_storage_map(void *priv_data,
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struct bpf_iter_aux_info *aux)
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{
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struct bpf_iter_seq_sk_storage_map_info *seq_info = priv_data;
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seq_info->map = aux->map;
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return 0;
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}
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static int bpf_iter_check_map(struct bpf_prog *prog,
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struct bpf_iter_aux_info *aux)
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{
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struct bpf_map *map = aux->map;
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if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
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return -EINVAL;
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if (prog->aux->max_rdonly_access > map->value_size)
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return -EACCES;
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return 0;
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}
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static const struct seq_operations bpf_sk_storage_map_seq_ops = {
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.start = bpf_sk_storage_map_seq_start,
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.next = bpf_sk_storage_map_seq_next,
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.stop = bpf_sk_storage_map_seq_stop,
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.show = bpf_sk_storage_map_seq_show,
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};
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static const struct bpf_iter_seq_info iter_seq_info = {
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.seq_ops = &bpf_sk_storage_map_seq_ops,
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.init_seq_private = bpf_iter_init_sk_storage_map,
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.fini_seq_private = NULL,
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.seq_priv_size = sizeof(struct bpf_iter_seq_sk_storage_map_info),
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};
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static struct bpf_iter_reg bpf_sk_storage_map_reg_info = {
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.target = "bpf_sk_storage_map",
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.check_target = bpf_iter_check_map,
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.req_linfo = BPF_ITER_LINK_MAP_FD,
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.ctx_arg_info_size = 2,
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.ctx_arg_info = {
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{ offsetof(struct bpf_iter__bpf_sk_storage_map, sk),
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PTR_TO_BTF_ID_OR_NULL },
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{ offsetof(struct bpf_iter__bpf_sk_storage_map, value),
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PTR_TO_RDWR_BUF_OR_NULL },
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},
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.seq_info = &iter_seq_info,
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};
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static int __init bpf_sk_storage_map_iter_init(void)
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{
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bpf_sk_storage_map_reg_info.ctx_arg_info[0].btf_id =
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btf_sock_ids[BTF_SOCK_TYPE_SOCK];
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return bpf_iter_reg_target(&bpf_sk_storage_map_reg_info);
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}
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late_initcall(bpf_sk_storage_map_iter_init);
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