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@xxxxxxxxxxxxxx> --- net/core/sock_map.c | 280 +++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 278 insertions(+), 2 deletions(-) diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 82494810d0ee..e1f05e3fa1d0 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -2,6 +2,7 @@ /* Copyright (c) 2017 - 2018 Covalent IO, Inc. http://covalent.io */ #include <linux/bpf.h> +#include <linux/btf_ids.h> #include <linux/filter.h> #include <linux/errno.h> #include <linux/file.h> @@ -703,6 +704,109 @@ const struct bpf_func_proto bpf_msg_redirect_map_proto = { .arg4_type = ARG_ANYTHING, }; +struct sock_map_seq_info { + struct bpf_map *map; + struct sock *sk; + u32 index; +}; + +struct bpf_iter__sockmap { + __bpf_md_ptr(struct bpf_iter_meta *, meta); + __bpf_md_ptr(struct bpf_map *, map); + __bpf_md_ptr(void *, key); + __bpf_md_ptr(struct sock *, sk); +}; + +DEFINE_BPF_ITER_FUNC(sockmap, struct bpf_iter_meta *meta, + struct bpf_map *map, void *key, + struct sock *sk) + +static void *sock_map_seq_lookup_elem(struct sock_map_seq_info *info) +{ + if (unlikely(info->index >= info->map->max_entries)) + return NULL; + + info->sk = __sock_map_lookup_elem(info->map, info->index); + + /* can't return sk directly, since that might be NULL */ + return info; +} + +static void *sock_map_seq_start(struct seq_file *seq, loff_t *pos) +{ + struct sock_map_seq_info *info = seq->private; + + if (*pos == 0) + ++*pos; + + /* pairs with sock_map_seq_stop */ + rcu_read_lock(); + return sock_map_seq_lookup_elem(info); +} + +static void *sock_map_seq_next(struct seq_file *seq, void *v, loff_t *pos) +{ + struct sock_map_seq_info *info = seq->private; + + ++*pos; + ++info->index; + + return sock_map_seq_lookup_elem(info); +} + +static int sock_map_seq_show(struct seq_file *seq, void *v) +{ + struct sock_map_seq_info *info = seq->private; + struct bpf_iter__sockmap ctx = {}; + struct bpf_iter_meta meta; + struct bpf_prog *prog; + + meta.seq = seq; + prog = bpf_iter_get_info(&meta, !v); + if (!prog) + return 0; + + ctx.meta = &meta; + ctx.map = info->map; + if (v) { + ctx.key = &info->index; + ctx.sk = info->sk; + } + + return bpf_iter_run_prog(prog, &ctx); +} + +static void sock_map_seq_stop(struct seq_file *seq, void *v) +{ + if (!v) + (void)sock_map_seq_show(seq, NULL); + + /* pairs with sock_map_seq_start */ + rcu_read_unlock(); +} + +static const struct seq_operations sock_map_seq_ops = { + .start = sock_map_seq_start, + .next = sock_map_seq_next, + .stop = sock_map_seq_stop, + .show = sock_map_seq_show, +}; + +static int sock_map_init_seq_private(void *priv_data, + struct bpf_iter_aux_info *aux) +{ + struct sock_map_seq_info *info = priv_data; + + info->map = aux->map; + return 0; +} + +static const struct bpf_iter_seq_info sock_map_iter_seq_info = { + .seq_ops = &sock_map_seq_ops, + .init_seq_private = sock_map_init_seq_private, + .seq_priv_size = sizeof(struct sock_map_seq_info), +}; + static int sock_map_btf_id; const struct bpf_map_ops sock_map_ops = { .map_meta_equal = bpf_map_meta_equal, @@ -717,6 +821,7 @@ const struct bpf_map_ops sock_map_ops = { .map_check_btf = map_check_no_btf, .map_btf_name = "bpf_stab", .map_btf_id = &sock_map_btf_id, + .iter_seq_info = &sock_map_iter_seq_info, }; struct bpf_shtab_elem { @@ -953,7 +1058,7 @@ static int sock_hash_get_next_key(struct bpf_map *map, void *key, if (!elem) goto find_first_elem; - elem_next = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&elem->node)), + elem_next = hlist_entry_safe(rcu_dereference(hlist_next_rcu(&elem->node)), struct bpf_shtab_elem, node); if (elem_next) { memcpy(key_next, elem_next->key, key_size); @@ -965,7 +1070,7 @@ static int sock_hash_get_next_key(struct bpf_map *map, void *key, find_first_elem: for (; i < htab->buckets_num; i++) { head = &sock_hash_select_bucket(htab, i)->head; - elem_next = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)), + elem_next = hlist_entry_safe(rcu_dereference(hlist_first_rcu(head)), struct bpf_shtab_elem, node); if (elem_next) { memcpy(key_next, elem_next->key, key_size); @@ -1199,6 +1304,117 @@ const struct bpf_func_proto bpf_msg_redirect_hash_proto = { .arg4_type = ARG_ANYTHING, }; +struct sock_hash_seq_info { + struct bpf_map *map; + struct bpf_shtab *htab; + u32 bucket_id; +}; + +static void *sock_hash_seq_find_next(struct sock_hash_seq_info *info, + struct bpf_shtab_elem *prev_elem) +{ + const struct bpf_shtab *htab = info->htab; + struct bpf_shtab_bucket *bucket; + struct bpf_shtab_elem *elem; + struct hlist_node *node; + + /* try to find next elem in the same bucket */ + if (prev_elem) { + node = rcu_dereference(hlist_next_rcu(&prev_elem->node)); + elem = hlist_entry_safe(node, struct bpf_shtab_elem, node); + if (elem) + return elem; + + /* no more elements, continue in the next bucket */ + info->bucket_id++; + } + + for (; info->bucket_id < htab->buckets_num; info->bucket_id++) { + bucket = &htab->buckets[info->bucket_id]; + node = rcu_dereference(hlist_first_rcu(&bucket->head)); + elem = hlist_entry_safe(node, struct bpf_shtab_elem, node); + if (elem) + return elem; + } + + return NULL; +} + +static void *sock_hash_seq_start(struct seq_file *seq, loff_t *pos) +{ + struct sock_hash_seq_info *info = seq->private; + + if (*pos == 0) + ++*pos; + + /* pairs with sock_hash_seq_stop */ + rcu_read_lock(); + return sock_hash_seq_find_next(info, NULL); +} + +static void *sock_hash_seq_next(struct seq_file *seq, void *v, loff_t *pos) +{ + struct sock_hash_seq_info *info = seq->private; + + ++*pos; + return sock_hash_seq_find_next(info, v); +} + +static int sock_hash_seq_show(struct seq_file *seq, void *v) +{ + struct sock_hash_seq_info *info = seq->private; + struct bpf_iter__sockmap ctx = {}; + struct bpf_shtab_elem *elem = v; + struct bpf_iter_meta meta; + struct bpf_prog *prog; + + meta.seq = seq; + prog = bpf_iter_get_info(&meta, !elem); + if (!prog) + return 0; + + ctx.meta = &meta; + ctx.map = info->map; + if (elem) { + ctx.key = elem->key; + ctx.sk = elem->sk; + } + + return bpf_iter_run_prog(prog, &ctx); +} + +static void sock_hash_seq_stop(struct seq_file *seq, void *v) +{ + if (!v) + (void)sock_hash_seq_show(seq, NULL); + + /* pairs with sock_hash_seq_start */ + rcu_read_unlock(); +} + +static const struct seq_operations sock_hash_seq_ops = { + .start = sock_hash_seq_start, + .next = sock_hash_seq_next, + .stop = sock_hash_seq_stop, + .show = sock_hash_seq_show, +}; + +static int sock_hash_init_seq_private(void *priv_data, + struct bpf_iter_aux_info *aux) +{ + struct sock_hash_seq_info *info = priv_data; + + info->map = aux->map; + info->htab = container_of(aux->map, struct bpf_shtab, map); + return 0; +} + +static const struct bpf_iter_seq_info sock_hash_iter_seq_info = { + .seq_ops = &sock_hash_seq_ops, + .init_seq_private = sock_hash_init_seq_private, + .seq_priv_size = sizeof(struct sock_hash_seq_info), +}; + static int sock_hash_map_btf_id; const struct bpf_map_ops sock_hash_ops = { .map_meta_equal = bpf_map_meta_equal, @@ -1213,6 +1429,7 @@ const struct bpf_map_ops sock_hash_ops = { .map_check_btf = map_check_no_btf, .map_btf_name = "bpf_shtab", .map_btf_id = &sock_hash_map_btf_id, + .iter_seq_info = &sock_hash_iter_seq_info, }; static struct sk_psock_progs *sock_map_progs(struct bpf_map *map) @@ -1323,3 +1540,62 @@ void sock_map_close(struct sock *sk, long timeout) release_sock(sk); saved_close(sk, timeout); } + +static int sock_map_iter_attach_target(struct bpf_prog *prog, + union bpf_iter_link_info *linfo, + struct bpf_iter_aux_info *aux) +{ + struct bpf_map *map; + int err = -EINVAL; + + if (!linfo->map.map_fd) + return -EBADF; + + map = bpf_map_get_with_uref(linfo->map.map_fd); + if (IS_ERR(map)) + return PTR_ERR(map); + + if (map->map_type != BPF_MAP_TYPE_SOCKMAP && + map->map_type != BPF_MAP_TYPE_SOCKHASH) + goto put_map; + + if (prog->aux->max_rdonly_access > map->key_size) { + err = -EACCES; + goto put_map; + } + + aux->map = map; + return 0; + +put_map: + bpf_map_put_with_uref(map); + return err; +} + +static void sock_map_iter_detach_target(struct bpf_iter_aux_info *aux) +{ + bpf_map_put_with_uref(aux->map); +} + +static struct bpf_iter_reg sock_map_iter_reg = { + .target = "sockmap", + .attach_target = sock_map_iter_attach_target, + .detach_target = sock_map_iter_detach_target, + .show_fdinfo = bpf_iter_map_show_fdinfo, + .fill_link_info = bpf_iter_map_fill_link_info, + .ctx_arg_info_size = 2, + .ctx_arg_info = { + { offsetof(struct bpf_iter__sockmap, key), + PTR_TO_RDONLY_BUF_OR_NULL }, + { offsetof(struct bpf_iter__sockmap, sk), + PTR_TO_BTF_ID_OR_NULL }, + }, +}; + +static int __init bpf_sockmap_iter_init(void) +{ + sock_map_iter_reg.ctx_arg_info[1].btf_id = + btf_sock_ids[BTF_SOCK_TYPE_SOCK]; + return bpf_iter_reg_target(&sock_map_iter_reg); +} +late_initcall(bpf_sockmap_iter_init); -- 2.25.1
