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/filter.h> |
8 | #include <net/xdp_sock.h> |
9 | #include <linux/slab.h> |
10 | #include <linux/sched.h> |
11 | #include <linux/btf_ids.h> |
12 | |
13 | #include "xsk.h" |
14 | |
15 | static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map, |
16 | struct xdp_sock __rcu **map_entry) |
17 | { |
18 | struct xsk_map_node *node; |
19 | |
20 | node = bpf_map_kzalloc(map: &map->map, size: sizeof(*node), |
21 | GFP_ATOMIC | __GFP_NOWARN); |
22 | if (!node) |
23 | return ERR_PTR(error: -ENOMEM); |
24 | |
25 | bpf_map_inc(map: &map->map); |
26 | atomic_inc(v: &map->count); |
27 | |
28 | node->map = map; |
29 | node->map_entry = map_entry; |
30 | return node; |
31 | } |
32 | |
33 | static void xsk_map_node_free(struct xsk_map_node *node) |
34 | { |
35 | struct xsk_map *map = node->map; |
36 | |
37 | bpf_map_put(map: &node->map->map); |
38 | kfree(objp: node); |
39 | atomic_dec(v: &map->count); |
40 | } |
41 | |
42 | static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node) |
43 | { |
44 | spin_lock_bh(lock: &xs->map_list_lock); |
45 | list_add_tail(new: &node->node, head: &xs->map_list); |
46 | spin_unlock_bh(lock: &xs->map_list_lock); |
47 | } |
48 | |
49 | static void xsk_map_sock_delete(struct xdp_sock *xs, |
50 | struct xdp_sock __rcu **map_entry) |
51 | { |
52 | struct xsk_map_node *n, *tmp; |
53 | |
54 | spin_lock_bh(lock: &xs->map_list_lock); |
55 | list_for_each_entry_safe(n, tmp, &xs->map_list, node) { |
56 | if (map_entry == n->map_entry) { |
57 | list_del(entry: &n->node); |
58 | xsk_map_node_free(node: n); |
59 | } |
60 | } |
61 | spin_unlock_bh(lock: &xs->map_list_lock); |
62 | } |
63 | |
64 | static struct bpf_map *xsk_map_alloc(union bpf_attr *attr) |
65 | { |
66 | struct xsk_map *m; |
67 | int numa_node; |
68 | u64 size; |
69 | |
70 | if (attr->max_entries == 0 || attr->key_size != 4 || |
71 | attr->value_size != 4 || |
72 | attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)) |
73 | return ERR_PTR(error: -EINVAL); |
74 | |
75 | numa_node = bpf_map_attr_numa_node(attr); |
76 | size = struct_size(m, xsk_map, attr->max_entries); |
77 | |
78 | m = bpf_map_area_alloc(size, numa_node); |
79 | if (!m) |
80 | return ERR_PTR(error: -ENOMEM); |
81 | |
82 | bpf_map_init_from_attr(map: &m->map, attr); |
83 | spin_lock_init(&m->lock); |
84 | |
85 | return &m->map; |
86 | } |
87 | |
88 | static u64 xsk_map_mem_usage(const struct bpf_map *map) |
89 | { |
90 | struct xsk_map *m = container_of(map, struct xsk_map, map); |
91 | |
92 | return struct_size(m, xsk_map, map->max_entries) + |
93 | (u64)atomic_read(v: &m->count) * sizeof(struct xsk_map_node); |
94 | } |
95 | |
96 | static void xsk_map_free(struct bpf_map *map) |
97 | { |
98 | struct xsk_map *m = container_of(map, struct xsk_map, map); |
99 | |
100 | synchronize_net(); |
101 | bpf_map_area_free(base: m); |
102 | } |
103 | |
104 | static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key) |
105 | { |
106 | struct xsk_map *m = container_of(map, struct xsk_map, map); |
107 | u32 index = key ? *(u32 *)key : U32_MAX; |
108 | u32 *next = next_key; |
109 | |
110 | if (index >= m->map.max_entries) { |
111 | *next = 0; |
112 | return 0; |
113 | } |
114 | |
115 | if (index == m->map.max_entries - 1) |
116 | return -ENOENT; |
117 | *next = index + 1; |
118 | return 0; |
119 | } |
120 | |
121 | static int xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf) |
122 | { |
123 | const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2; |
124 | struct bpf_insn *insn = insn_buf; |
125 | |
126 | *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0); |
127 | *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5); |
128 | *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *))); |
129 | *insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map)); |
130 | *insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp); |
131 | *insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock *), ret, ret, 0); |
132 | *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1); |
133 | *insn++ = BPF_MOV64_IMM(ret, 0); |
134 | return insn - insn_buf; |
135 | } |
136 | |
137 | /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or |
138 | * by local_bh_disable() (from XDP calls inside NAPI). The |
139 | * rcu_read_lock_bh_held() below makes lockdep accept both. |
140 | */ |
141 | static void *__xsk_map_lookup_elem(struct bpf_map *map, u32 key) |
142 | { |
143 | struct xsk_map *m = container_of(map, struct xsk_map, map); |
144 | |
145 | if (key >= map->max_entries) |
146 | return NULL; |
147 | |
148 | return rcu_dereference_check(m->xsk_map[key], rcu_read_lock_bh_held()); |
149 | } |
150 | |
151 | static void *xsk_map_lookup_elem(struct bpf_map *map, void *key) |
152 | { |
153 | return __xsk_map_lookup_elem(map, key: *(u32 *)key); |
154 | } |
155 | |
156 | static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key) |
157 | { |
158 | return ERR_PTR(error: -EOPNOTSUPP); |
159 | } |
160 | |
161 | static long xsk_map_update_elem(struct bpf_map *map, void *key, void *value, |
162 | u64 map_flags) |
163 | { |
164 | struct xsk_map *m = container_of(map, struct xsk_map, map); |
165 | struct xdp_sock __rcu **map_entry; |
166 | struct xdp_sock *xs, *old_xs; |
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: &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(map: m, map_entry); |
190 | if (IS_ERR(ptr: node)) { |
191 | sockfd_put(sock); |
192 | return PTR_ERR(ptr: node); |
193 | } |
194 | |
195 | spin_lock_bh(lock: &m->lock); |
196 | old_xs = rcu_dereference_protected(*map_entry, lockdep_is_held(&m->lock)); |
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 | rcu_assign_pointer(*map_entry, xs); |
209 | if (old_xs) |
210 | xsk_map_sock_delete(xs: old_xs, map_entry); |
211 | spin_unlock_bh(lock: &m->lock); |
212 | sockfd_put(sock); |
213 | return 0; |
214 | |
215 | out: |
216 | spin_unlock_bh(lock: &m->lock); |
217 | sockfd_put(sock); |
218 | xsk_map_node_free(node); |
219 | return err; |
220 | } |
221 | |
222 | static long 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 __rcu **map_entry; |
226 | struct xdp_sock *old_xs; |
227 | int k = *(u32 *)key; |
228 | |
229 | if (k >= map->max_entries) |
230 | return -EINVAL; |
231 | |
232 | spin_lock_bh(lock: &m->lock); |
233 | map_entry = &m->xsk_map[k]; |
234 | old_xs = unrcu_pointer(xchg(map_entry, NULL)); |
235 | if (old_xs) |
236 | xsk_map_sock_delete(xs: old_xs, map_entry); |
237 | spin_unlock_bh(lock: &m->lock); |
238 | |
239 | return 0; |
240 | } |
241 | |
242 | static long xsk_map_redirect(struct bpf_map *map, u64 index, u64 flags) |
243 | { |
244 | return __bpf_xdp_redirect_map(map, index, flags, flag_mask: 0, |
245 | lookup_elem: __xsk_map_lookup_elem); |
246 | } |
247 | |
248 | void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs, |
249 | struct xdp_sock __rcu **map_entry) |
250 | { |
251 | spin_lock_bh(lock: &map->lock); |
252 | if (rcu_access_pointer(*map_entry) == xs) { |
253 | rcu_assign_pointer(*map_entry, NULL); |
254 | xsk_map_sock_delete(xs, map_entry); |
255 | } |
256 | spin_unlock_bh(lock: &map->lock); |
257 | } |
258 | |
259 | static bool xsk_map_meta_equal(const struct bpf_map *meta0, |
260 | const struct bpf_map *meta1) |
261 | { |
262 | return meta0->max_entries == meta1->max_entries && |
263 | bpf_map_meta_equal(meta0, meta1); |
264 | } |
265 | |
266 | BTF_ID_LIST_SINGLE(xsk_map_btf_ids, struct, xsk_map) |
267 | const struct bpf_map_ops xsk_map_ops = { |
268 | .map_meta_equal = xsk_map_meta_equal, |
269 | .map_alloc = xsk_map_alloc, |
270 | .map_free = xsk_map_free, |
271 | .map_get_next_key = xsk_map_get_next_key, |
272 | .map_lookup_elem = xsk_map_lookup_elem, |
273 | .map_gen_lookup = xsk_map_gen_lookup, |
274 | .map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only, |
275 | .map_update_elem = xsk_map_update_elem, |
276 | .map_delete_elem = xsk_map_delete_elem, |
277 | .map_check_btf = map_check_no_btf, |
278 | .map_mem_usage = xsk_map_mem_usage, |
279 | .map_btf_id = &xsk_map_btf_ids[0], |
280 | .map_redirect = xsk_map_redirect, |
281 | }; |
282 | |