1 // SPDX-License-Identifier: GPL-2.0
2 /* XSKMAP used for AF_XDP sockets
3 * Copyright(c) 2018 Intel Corporation.
4 */
5
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
xsk_map_inc(struct xsk_map * map)14 int xsk_map_inc(struct xsk_map *map)
15 {
16 bpf_map_inc(&map->map);
17 return 0;
18 }
19
xsk_map_put(struct xsk_map * map)20 void xsk_map_put(struct xsk_map *map)
21 {
22 bpf_map_put(&map->map);
23 }
24
xsk_map_node_alloc(struct xsk_map * map,struct xdp_sock ** map_entry)25 static 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
xsk_map_node_free(struct xsk_map_node * node)46 static void xsk_map_node_free(struct xsk_map_node *node)
47 {
48 xsk_map_put(node->map);
49 kfree(node);
50 }
51
xsk_map_sock_add(struct xdp_sock * xs,struct xsk_map_node * node)52 static 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
xsk_map_sock_delete(struct xdp_sock * xs,struct xdp_sock ** map_entry)59 static 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
xsk_map_alloc(union bpf_attr * attr)74 static 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
xsk_map_free(struct bpf_map * map)109 static 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
xsk_map_get_next_key(struct bpf_map * map,void * key,void * next_key)118 static 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
xsk_map_gen_lookup(struct bpf_map * map,struct bpf_insn * insn_buf)135 static int 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
xsk_map_lookup_elem(struct bpf_map * map,void * key)151 static 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
xsk_map_lookup_elem_sys_only(struct bpf_map * map,void * key)157 static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key)
158 {
159 return ERR_PTR(-EOPNOTSUPP);
160 }
161
xsk_map_update_elem(struct bpf_map * map,void * key,void * value,u64 map_flags)162 static 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 map_entry = &m->xsk_map[i];
189 node = xsk_map_node_alloc(m, map_entry);
190 if (IS_ERR(node)) {
191 sockfd_put(sock);
192 return PTR_ERR(node);
193 }
194
195 spin_lock_bh(&m->lock);
196 old_xs = READ_ONCE(*map_entry);
197 if (old_xs == xs) {
198 err = 0;
199 goto out;
200 } else if (old_xs && map_flags == BPF_NOEXIST) {
201 err = -EEXIST;
202 goto out;
203 } else if (!old_xs && map_flags == BPF_EXIST) {
204 err = -ENOENT;
205 goto out;
206 }
207 xsk_map_sock_add(xs, node);
208 WRITE_ONCE(*map_entry, xs);
209 if (old_xs)
210 xsk_map_sock_delete(old_xs, map_entry);
211 spin_unlock_bh(&m->lock);
212 sockfd_put(sock);
213 return 0;
214
215 out:
216 spin_unlock_bh(&m->lock);
217 sockfd_put(sock);
218 xsk_map_node_free(node);
219 return err;
220 }
221
xsk_map_delete_elem(struct bpf_map * map,void * key)222 static int xsk_map_delete_elem(struct bpf_map *map, void *key)
223 {
224 struct xsk_map *m = container_of(map, struct xsk_map, map);
225 struct xdp_sock *old_xs, **map_entry;
226 int k = *(u32 *)key;
227
228 if (k >= map->max_entries)
229 return -EINVAL;
230
231 spin_lock_bh(&m->lock);
232 map_entry = &m->xsk_map[k];
233 old_xs = xchg(map_entry, NULL);
234 if (old_xs)
235 xsk_map_sock_delete(old_xs, map_entry);
236 spin_unlock_bh(&m->lock);
237
238 return 0;
239 }
240
xsk_map_try_sock_delete(struct xsk_map * map,struct xdp_sock * xs,struct xdp_sock ** map_entry)241 void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
242 struct xdp_sock **map_entry)
243 {
244 spin_lock_bh(&map->lock);
245 if (READ_ONCE(*map_entry) == xs) {
246 WRITE_ONCE(*map_entry, NULL);
247 xsk_map_sock_delete(xs, map_entry);
248 }
249 spin_unlock_bh(&map->lock);
250 }
251
xsk_map_meta_equal(const struct bpf_map * meta0,const struct bpf_map * meta1)252 static bool xsk_map_meta_equal(const struct bpf_map *meta0,
253 const struct bpf_map *meta1)
254 {
255 return meta0->max_entries == meta1->max_entries &&
256 bpf_map_meta_equal(meta0, meta1);
257 }
258
259 static int xsk_map_btf_id;
260 const struct bpf_map_ops xsk_map_ops = {
261 .map_meta_equal = xsk_map_meta_equal,
262 .map_alloc = xsk_map_alloc,
263 .map_free = xsk_map_free,
264 .map_get_next_key = xsk_map_get_next_key,
265 .map_lookup_elem = xsk_map_lookup_elem,
266 .map_gen_lookup = xsk_map_gen_lookup,
267 .map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,
268 .map_update_elem = xsk_map_update_elem,
269 .map_delete_elem = xsk_map_delete_elem,
270 .map_check_btf = map_check_no_btf,
271 .map_btf_name = "xsk_map",
272 .map_btf_id = &xsk_map_btf_id,
273 };
274