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bpf: introduce new bpf AF_XDP map type BPF_MAP_TYPE_XSKMAP
The xskmap is yet another BPF map, very much inspired by dev/cpu/sockmap, and is a holder of AF_XDP sockets. A user application adds AF_XDP sockets into the map, and by using the bpf_redirect_map helper, an XDP program can redirect XDP frames to an AF_XDP socket. Note that a socket that is bound to certain ifindex/queue index will *only* accept XDP frames from that netdev/queue index. If an XDP program tries to redirect from a netdev/queue index other than what the socket is bound to, the frame will not be received on the socket. A socket can reside in multiple maps. v3: Fixed race and simplified code. v2: Removed one indirection in map lookup. Signed-off-by: Björn Töpel <[email protected]> Signed-off-by: Alexei Starovoitov <[email protected]>
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Björn Töpel
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Alexei Starovoitov
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May 3, 2018
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,239 @@ | ||
| // SPDX-License-Identifier: GPL-2.0 | ||
| /* XSKMAP used for AF_XDP sockets | ||
| * Copyright(c) 2018 Intel Corporation. | ||
| * | ||
| * This program is free software; you can redistribute it and/or modify it | ||
| * under the terms and conditions of the GNU General Public License, | ||
| * version 2, as published by the Free Software Foundation. | ||
| * | ||
| * This program is distributed in the hope it will be useful, but WITHOUT | ||
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | ||
| * more details. | ||
| */ | ||
|
|
||
| #include <linux/bpf.h> | ||
| #include <linux/capability.h> | ||
| #include <net/xdp_sock.h> | ||
| #include <linux/slab.h> | ||
| #include <linux/sched.h> | ||
|
|
||
| struct xsk_map { | ||
| struct bpf_map map; | ||
| struct xdp_sock **xsk_map; | ||
| struct list_head __percpu *flush_list; | ||
| }; | ||
|
|
||
| static struct bpf_map *xsk_map_alloc(union bpf_attr *attr) | ||
| { | ||
| int cpu, err = -EINVAL; | ||
| struct xsk_map *m; | ||
| u64 cost; | ||
|
|
||
| if (!capable(CAP_NET_ADMIN)) | ||
| return ERR_PTR(-EPERM); | ||
|
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| if (attr->max_entries == 0 || attr->key_size != 4 || | ||
| attr->value_size != 4 || | ||
| attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)) | ||
| return ERR_PTR(-EINVAL); | ||
|
|
||
| m = kzalloc(sizeof(*m), GFP_USER); | ||
| if (!m) | ||
| return ERR_PTR(-ENOMEM); | ||
|
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| bpf_map_init_from_attr(&m->map, attr); | ||
|
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| cost = (u64)m->map.max_entries * sizeof(struct xdp_sock *); | ||
| cost += sizeof(struct list_head) * num_possible_cpus(); | ||
| if (cost >= U32_MAX - PAGE_SIZE) | ||
| goto free_m; | ||
|
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||
| m->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; | ||
|
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| /* Notice returns -EPERM on if map size is larger than memlock limit */ | ||
| err = bpf_map_precharge_memlock(m->map.pages); | ||
| if (err) | ||
| goto free_m; | ||
|
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| m->flush_list = alloc_percpu(struct list_head); | ||
| if (!m->flush_list) | ||
| goto free_m; | ||
|
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| for_each_possible_cpu(cpu) | ||
| INIT_LIST_HEAD(per_cpu_ptr(m->flush_list, cpu)); | ||
|
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| m->xsk_map = bpf_map_area_alloc(m->map.max_entries * | ||
| sizeof(struct xdp_sock *), | ||
| m->map.numa_node); | ||
| if (!m->xsk_map) | ||
| goto free_percpu; | ||
| return &m->map; | ||
|
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||
| free_percpu: | ||
| free_percpu(m->flush_list); | ||
| free_m: | ||
| kfree(m); | ||
| return ERR_PTR(err); | ||
| } | ||
|
|
||
| static void xsk_map_free(struct bpf_map *map) | ||
| { | ||
| struct xsk_map *m = container_of(map, struct xsk_map, map); | ||
| int i; | ||
|
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| synchronize_net(); | ||
|
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| for (i = 0; i < map->max_entries; i++) { | ||
| struct xdp_sock *xs; | ||
|
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| xs = m->xsk_map[i]; | ||
| if (!xs) | ||
| continue; | ||
|
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| sock_put((struct sock *)xs); | ||
| } | ||
|
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| free_percpu(m->flush_list); | ||
| bpf_map_area_free(m->xsk_map); | ||
| kfree(m); | ||
| } | ||
|
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||
| static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key) | ||
| { | ||
| struct xsk_map *m = container_of(map, struct xsk_map, map); | ||
| u32 index = key ? *(u32 *)key : U32_MAX; | ||
| u32 *next = next_key; | ||
|
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| if (index >= m->map.max_entries) { | ||
| *next = 0; | ||
| return 0; | ||
| } | ||
|
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| if (index == m->map.max_entries - 1) | ||
| return -ENOENT; | ||
| *next = index + 1; | ||
| return 0; | ||
| } | ||
|
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| struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map, u32 key) | ||
| { | ||
| struct xsk_map *m = container_of(map, struct xsk_map, map); | ||
| struct xdp_sock *xs; | ||
|
|
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| if (key >= map->max_entries) | ||
| return NULL; | ||
|
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| xs = READ_ONCE(m->xsk_map[key]); | ||
| return xs; | ||
| } | ||
|
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| int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp, | ||
| struct xdp_sock *xs) | ||
| { | ||
| struct xsk_map *m = container_of(map, struct xsk_map, map); | ||
| struct list_head *flush_list = this_cpu_ptr(m->flush_list); | ||
| int err; | ||
|
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| err = xsk_rcv(xs, xdp); | ||
| if (err) | ||
| return err; | ||
|
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| if (!xs->flush_node.prev) | ||
| list_add(&xs->flush_node, flush_list); | ||
|
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| return 0; | ||
| } | ||
|
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| void __xsk_map_flush(struct bpf_map *map) | ||
| { | ||
| struct xsk_map *m = container_of(map, struct xsk_map, map); | ||
| struct list_head *flush_list = this_cpu_ptr(m->flush_list); | ||
| struct xdp_sock *xs, *tmp; | ||
|
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| list_for_each_entry_safe(xs, tmp, flush_list, flush_node) { | ||
| xsk_flush(xs); | ||
| __list_del(xs->flush_node.prev, xs->flush_node.next); | ||
| xs->flush_node.prev = NULL; | ||
| } | ||
| } | ||
|
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| static void *xsk_map_lookup_elem(struct bpf_map *map, void *key) | ||
| { | ||
| return NULL; | ||
| } | ||
|
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| static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value, | ||
| u64 map_flags) | ||
| { | ||
| struct xsk_map *m = container_of(map, struct xsk_map, map); | ||
| u32 i = *(u32 *)key, fd = *(u32 *)value; | ||
| struct xdp_sock *xs, *old_xs; | ||
| struct socket *sock; | ||
| int err; | ||
|
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| if (unlikely(map_flags > BPF_EXIST)) | ||
| return -EINVAL; | ||
| if (unlikely(i >= m->map.max_entries)) | ||
| return -E2BIG; | ||
| if (unlikely(map_flags == BPF_NOEXIST)) | ||
| return -EEXIST; | ||
|
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| sock = sockfd_lookup(fd, &err); | ||
| if (!sock) | ||
| return err; | ||
|
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| if (sock->sk->sk_family != PF_XDP) { | ||
| sockfd_put(sock); | ||
| return -EOPNOTSUPP; | ||
| } | ||
|
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| xs = (struct xdp_sock *)sock->sk; | ||
|
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| if (!xsk_is_setup_for_bpf_map(xs)) { | ||
| sockfd_put(sock); | ||
| return -EOPNOTSUPP; | ||
| } | ||
|
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| sock_hold(sock->sk); | ||
|
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| old_xs = xchg(&m->xsk_map[i], xs); | ||
| if (old_xs) { | ||
| /* Make sure we've flushed everything. */ | ||
| synchronize_net(); | ||
| sock_put((struct sock *)old_xs); | ||
| } | ||
|
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| sockfd_put(sock); | ||
| return 0; | ||
| } | ||
|
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| static int xsk_map_delete_elem(struct bpf_map *map, void *key) | ||
| { | ||
| struct xsk_map *m = container_of(map, struct xsk_map, map); | ||
| struct xdp_sock *old_xs; | ||
| int k = *(u32 *)key; | ||
|
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| if (k >= map->max_entries) | ||
| return -EINVAL; | ||
|
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| old_xs = xchg(&m->xsk_map[k], NULL); | ||
| if (old_xs) { | ||
| /* Make sure we've flushed everything. */ | ||
| synchronize_net(); | ||
| sock_put((struct sock *)old_xs); | ||
| } | ||
|
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| return 0; | ||
| } | ||
|
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| const struct bpf_map_ops xsk_map_ops = { | ||
| .map_alloc = xsk_map_alloc, | ||
| .map_free = xsk_map_free, | ||
| .map_get_next_key = xsk_map_get_next_key, | ||
| .map_lookup_elem = xsk_map_lookup_elem, | ||
| .map_update_elem = xsk_map_update_elem, | ||
| .map_delete_elem = xsk_map_delete_elem, | ||
| }; | ||
|
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||
|
|
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