From 5ce6e77c7edf7310a0ff9532fd6b9693c082ab32 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 23 Jul 2020 11:41:16 -0700 Subject: [PATCH] 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 Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200723184116.590602-1-yhs@fb.com --- net/core/bpf_sk_storage.c | 206 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 206 insertions(+) diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c index 6f921c4..eafcd15 100644 --- a/net/core/bpf_sk_storage.c +++ b/net/core/bpf_sk_storage.c @@ -6,6 +6,7 @@ #include #include #include +#include #include #include #include @@ -1217,3 +1218,208 @@ 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 > 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 struct bpf_iter_reg bpf_sk_storage_map_reg_info = { + .target = "bpf_sk_storage_map", + .check_target = bpf_iter_check_map, + .req_linfo = 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_RDWR_BUF_OR_NULL }, + }, + .seq_info = &iter_seq_info, +}; + +static int __init bpf_sk_storage_map_iter_init(void) +{ + bpf_sk_storage_map_reg_info.ctx_arg_info[0].btf_id = + btf_sock_ids[BTF_SOCK_TYPE_SOCK]; + return bpf_iter_reg_target(&bpf_sk_storage_map_reg_info); +} +late_initcall(bpf_sk_storage_map_iter_init); -- 2.7.4