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6#include <linux/bpf.h>
7#include <linux/capability.h>
8#include <net/xdp_sock.h>
9#include <linux/slab.h>
10#include <linux/sched.h>
11
12#include "xsk.h"
13
14int xsk_map_inc(struct xsk_map *map)
15{
16 bpf_map_inc(&map->map);
17 return 0;
18}
19
20void xsk_map_put(struct xsk_map *map)
21{
22 bpf_map_put(&map->map);
23}
24
25static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map,
26 struct xdp_sock **map_entry)
27{
28 struct xsk_map_node *node;
29 int err;
30
31 node = kzalloc(sizeof(*node), GFP_ATOMIC | __GFP_NOWARN);
32 if (!node)
33 return ERR_PTR(-ENOMEM);
34
35 err = xsk_map_inc(map);
36 if (err) {
37 kfree(node);
38 return ERR_PTR(err);
39 }
40
41 node->map = map;
42 node->map_entry = map_entry;
43 return node;
44}
45
46static void xsk_map_node_free(struct xsk_map_node *node)
47{
48 xsk_map_put(node->map);
49 kfree(node);
50}
51
52static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node)
53{
54 spin_lock_bh(&xs->map_list_lock);
55 list_add_tail(&node->node, &xs->map_list);
56 spin_unlock_bh(&xs->map_list_lock);
57}
58
59static void xsk_map_sock_delete(struct xdp_sock *xs,
60 struct xdp_sock **map_entry)
61{
62 struct xsk_map_node *n, *tmp;
63
64 spin_lock_bh(&xs->map_list_lock);
65 list_for_each_entry_safe(n, tmp, &xs->map_list, node) {
66 if (map_entry == n->map_entry) {
67 list_del(&n->node);
68 xsk_map_node_free(n);
69 }
70 }
71 spin_unlock_bh(&xs->map_list_lock);
72}
73
74static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
75{
76 struct bpf_map_memory mem;
77 int err, numa_node;
78 struct xsk_map *m;
79 u64 size;
80
81 if (!capable(CAP_NET_ADMIN))
82 return ERR_PTR(-EPERM);
83
84 if (attr->max_entries == 0 || attr->key_size != 4 ||
85 attr->value_size != 4 ||
86 attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY))
87 return ERR_PTR(-EINVAL);
88
89 numa_node = bpf_map_attr_numa_node(attr);
90 size = struct_size(m, xsk_map, attr->max_entries);
91
92 err = bpf_map_charge_init(&mem, size);
93 if (err < 0)
94 return ERR_PTR(err);
95
96 m = bpf_map_area_alloc(size, numa_node);
97 if (!m) {
98 bpf_map_charge_finish(&mem);
99 return ERR_PTR(-ENOMEM);
100 }
101
102 bpf_map_init_from_attr(&m->map, attr);
103 bpf_map_charge_move(&m->map.memory, &mem);
104 spin_lock_init(&m->lock);
105
106 return &m->map;
107}
108
109static void xsk_map_free(struct bpf_map *map)
110{
111 struct xsk_map *m = container_of(map, struct xsk_map, map);
112
113 bpf_clear_redirect_map(map);
114 synchronize_net();
115 bpf_map_area_free(m);
116}
117
118static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
119{
120 struct xsk_map *m = container_of(map, struct xsk_map, map);
121 u32 index = key ? *(u32 *)key : U32_MAX;
122 u32 *next = next_key;
123
124 if (index >= m->map.max_entries) {
125 *next = 0;
126 return 0;
127 }
128
129 if (index == m->map.max_entries - 1)
130 return -ENOENT;
131 *next = index + 1;
132 return 0;
133}
134
135static u32 xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
136{
137 const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2;
138 struct bpf_insn *insn = insn_buf;
139
140 *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
141 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
142 *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *)));
143 *insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map));
144 *insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp);
145 *insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock *), ret, ret, 0);
146 *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
147 *insn++ = BPF_MOV64_IMM(ret, 0);
148 return insn - insn_buf;
149}
150
151static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
152{
153 WARN_ON_ONCE(!rcu_read_lock_held());
154 return __xsk_map_lookup_elem(map, *(u32 *)key);
155}
156
157static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key)
158{
159 return ERR_PTR(-EOPNOTSUPP);
160}
161
162static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value,
163 u64 map_flags)
164{
165 struct xsk_map *m = container_of(map, struct xsk_map, map);
166 struct xdp_sock *xs, *old_xs, **map_entry;
167 u32 i = *(u32 *)key, fd = *(u32 *)value;
168 struct xsk_map_node *node;
169 struct socket *sock;
170 int err;
171
172 if (unlikely(map_flags > BPF_EXIST))
173 return -EINVAL;
174 if (unlikely(i >= m->map.max_entries))
175 return -E2BIG;
176
177 sock = sockfd_lookup(fd, &err);
178 if (!sock)
179 return err;
180
181 if (sock->sk->sk_family != PF_XDP) {
182 sockfd_put(sock);
183 return -EOPNOTSUPP;
184 }
185
186 xs = (struct xdp_sock *)sock->sk;
187
188 if (!xsk_is_setup_for_bpf_map(xs)) {
189 sockfd_put(sock);
190 return -EOPNOTSUPP;
191 }
192
193 map_entry = &m->xsk_map[i];
194 node = xsk_map_node_alloc(m, map_entry);
195 if (IS_ERR(node)) {
196 sockfd_put(sock);
197 return PTR_ERR(node);
198 }
199
200 spin_lock_bh(&m->lock);
201 old_xs = READ_ONCE(*map_entry);
202 if (old_xs == xs) {
203 err = 0;
204 goto out;
205 } else if (old_xs && map_flags == BPF_NOEXIST) {
206 err = -EEXIST;
207 goto out;
208 } else if (!old_xs && map_flags == BPF_EXIST) {
209 err = -ENOENT;
210 goto out;
211 }
212 xsk_map_sock_add(xs, node);
213 WRITE_ONCE(*map_entry, xs);
214 if (old_xs)
215 xsk_map_sock_delete(old_xs, map_entry);
216 spin_unlock_bh(&m->lock);
217 sockfd_put(sock);
218 return 0;
219
220out:
221 spin_unlock_bh(&m->lock);
222 sockfd_put(sock);
223 xsk_map_node_free(node);
224 return err;
225}
226
227static int xsk_map_delete_elem(struct bpf_map *map, void *key)
228{
229 struct xsk_map *m = container_of(map, struct xsk_map, map);
230 struct xdp_sock *old_xs, **map_entry;
231 int k = *(u32 *)key;
232
233 if (k >= map->max_entries)
234 return -EINVAL;
235
236 spin_lock_bh(&m->lock);
237 map_entry = &m->xsk_map[k];
238 old_xs = xchg(map_entry, NULL);
239 if (old_xs)
240 xsk_map_sock_delete(old_xs, map_entry);
241 spin_unlock_bh(&m->lock);
242
243 return 0;
244}
245
246void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
247 struct xdp_sock **map_entry)
248{
249 spin_lock_bh(&map->lock);
250 if (READ_ONCE(*map_entry) == xs) {
251 WRITE_ONCE(*map_entry, NULL);
252 xsk_map_sock_delete(xs, map_entry);
253 }
254 spin_unlock_bh(&map->lock);
255}
256
257static int xsk_map_btf_id;
258const struct bpf_map_ops xsk_map_ops = {
259 .map_alloc = xsk_map_alloc,
260 .map_free = xsk_map_free,
261 .map_get_next_key = xsk_map_get_next_key,
262 .map_lookup_elem = xsk_map_lookup_elem,
263 .map_gen_lookup = xsk_map_gen_lookup,
264 .map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,
265 .map_update_elem = xsk_map_update_elem,
266 .map_delete_elem = xsk_map_delete_elem,
267 .map_check_btf = map_check_no_btf,
268 .map_btf_name = "xsk_map",
269 .map_btf_id = &xsk_map_btf_id,
270};
271
