xsk: Move xskmap.c to net/xdp/
The XSKMAP is partly implemented by net/xdp/xsk.c. Move xskmap.c from
kernel/bpf/ to net/xdp/, which is the logical place for AF_XDP related
code. Also, move AF_XDP struct definitions, and function declarations
only used by AF_XDP internals into net/xdp/xsk.h.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200520192103.355233-3-bjorn.topel@gmail.com
diff --git a/net/xdp/xskmap.c b/net/xdp/xskmap.c
new file mode 100644
index 0000000..1dc7208
--- /dev/null
+++ b/net/xdp/xskmap.c
@@ -0,0 +1,267 @@
+// SPDX-License-Identifier: GPL-2.0
+/* XSKMAP used for AF_XDP sockets
+ * Copyright(c) 2018 Intel Corporation.
+ */
+
+#include <linux/bpf.h>
+#include <linux/capability.h>
+#include <net/xdp_sock.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+
+#include "xsk.h"
+
+int xsk_map_inc(struct xsk_map *map)
+{
+ bpf_map_inc(&map->map);
+ return 0;
+}
+
+void xsk_map_put(struct xsk_map *map)
+{
+ bpf_map_put(&map->map);
+}
+
+static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map,
+ struct xdp_sock **map_entry)
+{
+ struct xsk_map_node *node;
+ int err;
+
+ node = kzalloc(sizeof(*node), GFP_ATOMIC | __GFP_NOWARN);
+ if (!node)
+ return ERR_PTR(-ENOMEM);
+
+ err = xsk_map_inc(map);
+ if (err) {
+ kfree(node);
+ return ERR_PTR(err);
+ }
+
+ node->map = map;
+ node->map_entry = map_entry;
+ return node;
+}
+
+static void xsk_map_node_free(struct xsk_map_node *node)
+{
+ xsk_map_put(node->map);
+ kfree(node);
+}
+
+static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node)
+{
+ spin_lock_bh(&xs->map_list_lock);
+ list_add_tail(&node->node, &xs->map_list);
+ spin_unlock_bh(&xs->map_list_lock);
+}
+
+static void xsk_map_sock_delete(struct xdp_sock *xs,
+ struct xdp_sock **map_entry)
+{
+ struct xsk_map_node *n, *tmp;
+
+ spin_lock_bh(&xs->map_list_lock);
+ list_for_each_entry_safe(n, tmp, &xs->map_list, node) {
+ if (map_entry == n->map_entry) {
+ list_del(&n->node);
+ xsk_map_node_free(n);
+ }
+ }
+ spin_unlock_bh(&xs->map_list_lock);
+}
+
+static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
+{
+ struct bpf_map_memory mem;
+ int err, numa_node;
+ struct xsk_map *m;
+ u64 size;
+
+ if (!capable(CAP_NET_ADMIN))
+ return ERR_PTR(-EPERM);
+
+ 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);
+
+ numa_node = bpf_map_attr_numa_node(attr);
+ size = struct_size(m, xsk_map, attr->max_entries);
+
+ err = bpf_map_charge_init(&mem, size);
+ if (err < 0)
+ return ERR_PTR(err);
+
+ m = bpf_map_area_alloc(size, numa_node);
+ if (!m) {
+ bpf_map_charge_finish(&mem);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ bpf_map_init_from_attr(&m->map, attr);
+ bpf_map_charge_move(&m->map.memory, &mem);
+ spin_lock_init(&m->lock);
+
+ return &m->map;
+}
+
+static void xsk_map_free(struct bpf_map *map)
+{
+ struct xsk_map *m = container_of(map, struct xsk_map, map);
+
+ bpf_clear_redirect_map(map);
+ synchronize_net();
+ bpf_map_area_free(m);
+}
+
+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;
+
+ if (index >= m->map.max_entries) {
+ *next = 0;
+ return 0;
+ }
+
+ if (index == m->map.max_entries - 1)
+ return -ENOENT;
+ *next = index + 1;
+ return 0;
+}
+
+static u32 xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
+{
+ const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2;
+ struct bpf_insn *insn = insn_buf;
+
+ *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
+ *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
+ *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *)));
+ *insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map));
+ *insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp);
+ *insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock *), ret, ret, 0);
+ *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
+ *insn++ = BPF_MOV64_IMM(ret, 0);
+ return insn - insn_buf;
+}
+
+static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
+{
+ WARN_ON_ONCE(!rcu_read_lock_held());
+ return __xsk_map_lookup_elem(map, *(u32 *)key);
+}
+
+static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key)
+{
+ return ERR_PTR(-EOPNOTSUPP);
+}
+
+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);
+ struct xdp_sock *xs, *old_xs, **map_entry;
+ u32 i = *(u32 *)key, fd = *(u32 *)value;
+ struct xsk_map_node *node;
+ struct socket *sock;
+ int err;
+
+ if (unlikely(map_flags > BPF_EXIST))
+ return -EINVAL;
+ if (unlikely(i >= m->map.max_entries))
+ return -E2BIG;
+
+ sock = sockfd_lookup(fd, &err);
+ if (!sock)
+ return err;
+
+ if (sock->sk->sk_family != PF_XDP) {
+ sockfd_put(sock);
+ return -EOPNOTSUPP;
+ }
+
+ xs = (struct xdp_sock *)sock->sk;
+
+ if (!xsk_is_setup_for_bpf_map(xs)) {
+ sockfd_put(sock);
+ return -EOPNOTSUPP;
+ }
+
+ map_entry = &m->xsk_map[i];
+ node = xsk_map_node_alloc(m, map_entry);
+ if (IS_ERR(node)) {
+ sockfd_put(sock);
+ return PTR_ERR(node);
+ }
+
+ spin_lock_bh(&m->lock);
+ old_xs = READ_ONCE(*map_entry);
+ if (old_xs == xs) {
+ err = 0;
+ goto out;
+ } else if (old_xs && map_flags == BPF_NOEXIST) {
+ err = -EEXIST;
+ goto out;
+ } else if (!old_xs && map_flags == BPF_EXIST) {
+ err = -ENOENT;
+ goto out;
+ }
+ xsk_map_sock_add(xs, node);
+ WRITE_ONCE(*map_entry, xs);
+ if (old_xs)
+ xsk_map_sock_delete(old_xs, map_entry);
+ spin_unlock_bh(&m->lock);
+ sockfd_put(sock);
+ return 0;
+
+out:
+ spin_unlock_bh(&m->lock);
+ sockfd_put(sock);
+ xsk_map_node_free(node);
+ return err;
+}
+
+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, **map_entry;
+ int k = *(u32 *)key;
+
+ if (k >= map->max_entries)
+ return -EINVAL;
+
+ spin_lock_bh(&m->lock);
+ map_entry = &m->xsk_map[k];
+ old_xs = xchg(map_entry, NULL);
+ if (old_xs)
+ xsk_map_sock_delete(old_xs, map_entry);
+ spin_unlock_bh(&m->lock);
+
+ return 0;
+}
+
+void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
+ struct xdp_sock **map_entry)
+{
+ spin_lock_bh(&map->lock);
+ if (READ_ONCE(*map_entry) == xs) {
+ WRITE_ONCE(*map_entry, NULL);
+ xsk_map_sock_delete(xs, map_entry);
+ }
+ spin_unlock_bh(&map->lock);
+}
+
+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_gen_lookup = xsk_map_gen_lookup,
+ .map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,
+ .map_update_elem = xsk_map_update_elem,
+ .map_delete_elem = xsk_map_delete_elem,
+ .map_check_btf = map_check_no_btf,
+};