Commit | Line | Data |
---|---|---|
ef456144 CG |
1 | /* |
2 | * To speed up listener socket lookup, create an array to store all sockets | |
3 | * listening on the same port. This allows a decision to be made after finding | |
538950a1 CG |
4 | * the first socket. An optional BPF program can also be configured for |
5 | * selecting the socket index from the array of available sockets. | |
ef456144 CG |
6 | */ |
7 | ||
8 | #include <net/sock_reuseport.h> | |
538950a1 | 9 | #include <linux/bpf.h> |
ef456144 CG |
10 | #include <linux/rcupdate.h> |
11 | ||
12 | #define INIT_SOCKS 128 | |
13 | ||
14 | static DEFINE_SPINLOCK(reuseport_lock); | |
15 | ||
16 | static struct sock_reuseport *__reuseport_alloc(u16 max_socks) | |
17 | { | |
18 | size_t size = sizeof(struct sock_reuseport) + | |
19 | sizeof(struct sock *) * max_socks; | |
20 | struct sock_reuseport *reuse = kzalloc(size, GFP_ATOMIC); | |
21 | ||
22 | if (!reuse) | |
23 | return NULL; | |
24 | ||
25 | reuse->max_socks = max_socks; | |
26 | ||
538950a1 | 27 | RCU_INIT_POINTER(reuse->prog, NULL); |
ef456144 CG |
28 | return reuse; |
29 | } | |
30 | ||
31 | int reuseport_alloc(struct sock *sk) | |
32 | { | |
33 | struct sock_reuseport *reuse; | |
34 | ||
35 | /* bh lock used since this function call may precede hlist lock in | |
36 | * soft irq of receive path or setsockopt from process context | |
37 | */ | |
38 | spin_lock_bh(&reuseport_lock); | |
39 | WARN_ONCE(rcu_dereference_protected(sk->sk_reuseport_cb, | |
40 | lockdep_is_held(&reuseport_lock)), | |
41 | "multiple allocations for the same socket"); | |
42 | reuse = __reuseport_alloc(INIT_SOCKS); | |
43 | if (!reuse) { | |
44 | spin_unlock_bh(&reuseport_lock); | |
45 | return -ENOMEM; | |
46 | } | |
47 | ||
48 | reuse->socks[0] = sk; | |
49 | reuse->num_socks = 1; | |
50 | rcu_assign_pointer(sk->sk_reuseport_cb, reuse); | |
51 | ||
52 | spin_unlock_bh(&reuseport_lock); | |
53 | ||
54 | return 0; | |
55 | } | |
56 | EXPORT_SYMBOL(reuseport_alloc); | |
57 | ||
58 | static struct sock_reuseport *reuseport_grow(struct sock_reuseport *reuse) | |
59 | { | |
60 | struct sock_reuseport *more_reuse; | |
61 | u32 more_socks_size, i; | |
62 | ||
63 | more_socks_size = reuse->max_socks * 2U; | |
64 | if (more_socks_size > U16_MAX) | |
65 | return NULL; | |
66 | ||
67 | more_reuse = __reuseport_alloc(more_socks_size); | |
68 | if (!more_reuse) | |
69 | return NULL; | |
70 | ||
71 | more_reuse->max_socks = more_socks_size; | |
72 | more_reuse->num_socks = reuse->num_socks; | |
538950a1 | 73 | more_reuse->prog = reuse->prog; |
ef456144 CG |
74 | |
75 | memcpy(more_reuse->socks, reuse->socks, | |
76 | reuse->num_socks * sizeof(struct sock *)); | |
77 | ||
78 | for (i = 0; i < reuse->num_socks; ++i) | |
79 | rcu_assign_pointer(reuse->socks[i]->sk_reuseport_cb, | |
80 | more_reuse); | |
81 | ||
538950a1 CG |
82 | /* Note: we use kfree_rcu here instead of reuseport_free_rcu so |
83 | * that reuse and more_reuse can temporarily share a reference | |
84 | * to prog. | |
85 | */ | |
ef456144 CG |
86 | kfree_rcu(reuse, rcu); |
87 | return more_reuse; | |
88 | } | |
89 | ||
90 | /** | |
91 | * reuseport_add_sock - Add a socket to the reuseport group of another. | |
92 | * @sk: New socket to add to the group. | |
93 | * @sk2: Socket belonging to the existing reuseport group. | |
94 | * May return ENOMEM and not add socket to group under memory pressure. | |
95 | */ | |
b4ace4f1 | 96 | int reuseport_add_sock(struct sock *sk, struct sock *sk2) |
ef456144 CG |
97 | { |
98 | struct sock_reuseport *reuse; | |
99 | ||
b4ace4f1 CG |
100 | if (!rcu_access_pointer(sk2->sk_reuseport_cb)) { |
101 | int err = reuseport_alloc(sk2); | |
102 | ||
103 | if (err) | |
104 | return err; | |
105 | } | |
106 | ||
ef456144 CG |
107 | spin_lock_bh(&reuseport_lock); |
108 | reuse = rcu_dereference_protected(sk2->sk_reuseport_cb, | |
109 | lockdep_is_held(&reuseport_lock)), | |
110 | WARN_ONCE(rcu_dereference_protected(sk->sk_reuseport_cb, | |
111 | lockdep_is_held(&reuseport_lock)), | |
112 | "socket already in reuseport group"); | |
113 | ||
114 | if (reuse->num_socks == reuse->max_socks) { | |
115 | reuse = reuseport_grow(reuse); | |
116 | if (!reuse) { | |
117 | spin_unlock_bh(&reuseport_lock); | |
118 | return -ENOMEM; | |
119 | } | |
120 | } | |
121 | ||
122 | reuse->socks[reuse->num_socks] = sk; | |
123 | /* paired with smp_rmb() in reuseport_select_sock() */ | |
124 | smp_wmb(); | |
125 | reuse->num_socks++; | |
126 | rcu_assign_pointer(sk->sk_reuseport_cb, reuse); | |
127 | ||
128 | spin_unlock_bh(&reuseport_lock); | |
129 | ||
130 | return 0; | |
131 | } | |
132 | EXPORT_SYMBOL(reuseport_add_sock); | |
133 | ||
538950a1 CG |
134 | static void reuseport_free_rcu(struct rcu_head *head) |
135 | { | |
136 | struct sock_reuseport *reuse; | |
137 | ||
138 | reuse = container_of(head, struct sock_reuseport, rcu); | |
139 | if (reuse->prog) | |
140 | bpf_prog_destroy(reuse->prog); | |
141 | kfree(reuse); | |
142 | } | |
143 | ||
ef456144 CG |
144 | void reuseport_detach_sock(struct sock *sk) |
145 | { | |
146 | struct sock_reuseport *reuse; | |
147 | int i; | |
148 | ||
149 | spin_lock_bh(&reuseport_lock); | |
150 | reuse = rcu_dereference_protected(sk->sk_reuseport_cb, | |
151 | lockdep_is_held(&reuseport_lock)); | |
152 | rcu_assign_pointer(sk->sk_reuseport_cb, NULL); | |
153 | ||
154 | for (i = 0; i < reuse->num_socks; i++) { | |
155 | if (reuse->socks[i] == sk) { | |
156 | reuse->socks[i] = reuse->socks[reuse->num_socks - 1]; | |
157 | reuse->num_socks--; | |
158 | if (reuse->num_socks == 0) | |
538950a1 | 159 | call_rcu(&reuse->rcu, reuseport_free_rcu); |
ef456144 CG |
160 | break; |
161 | } | |
162 | } | |
163 | spin_unlock_bh(&reuseport_lock); | |
164 | } | |
165 | EXPORT_SYMBOL(reuseport_detach_sock); | |
166 | ||
538950a1 CG |
167 | static struct sock *run_bpf(struct sock_reuseport *reuse, u16 socks, |
168 | struct bpf_prog *prog, struct sk_buff *skb, | |
169 | int hdr_len) | |
170 | { | |
171 | struct sk_buff *nskb = NULL; | |
172 | u32 index; | |
173 | ||
174 | if (skb_shared(skb)) { | |
175 | nskb = skb_clone(skb, GFP_ATOMIC); | |
176 | if (!nskb) | |
177 | return NULL; | |
178 | skb = nskb; | |
179 | } | |
180 | ||
181 | /* temporarily advance data past protocol header */ | |
182 | if (!pskb_pull(skb, hdr_len)) { | |
00ce3a15 | 183 | kfree_skb(nskb); |
538950a1 CG |
184 | return NULL; |
185 | } | |
186 | index = bpf_prog_run_save_cb(prog, skb); | |
187 | __skb_push(skb, hdr_len); | |
188 | ||
189 | consume_skb(nskb); | |
190 | ||
191 | if (index >= socks) | |
192 | return NULL; | |
193 | ||
194 | return reuse->socks[index]; | |
195 | } | |
196 | ||
ef456144 CG |
197 | /** |
198 | * reuseport_select_sock - Select a socket from an SO_REUSEPORT group. | |
199 | * @sk: First socket in the group. | |
538950a1 CG |
200 | * @hash: When no BPF filter is available, use this hash to select. |
201 | * @skb: skb to run through BPF filter. | |
202 | * @hdr_len: BPF filter expects skb data pointer at payload data. If | |
203 | * the skb does not yet point at the payload, this parameter represents | |
204 | * how far the pointer needs to advance to reach the payload. | |
ef456144 CG |
205 | * Returns a socket that should receive the packet (or NULL on error). |
206 | */ | |
538950a1 CG |
207 | struct sock *reuseport_select_sock(struct sock *sk, |
208 | u32 hash, | |
209 | struct sk_buff *skb, | |
210 | int hdr_len) | |
ef456144 CG |
211 | { |
212 | struct sock_reuseport *reuse; | |
538950a1 | 213 | struct bpf_prog *prog; |
ef456144 CG |
214 | struct sock *sk2 = NULL; |
215 | u16 socks; | |
216 | ||
217 | rcu_read_lock(); | |
218 | reuse = rcu_dereference(sk->sk_reuseport_cb); | |
219 | ||
220 | /* if memory allocation failed or add call is not yet complete */ | |
221 | if (!reuse) | |
222 | goto out; | |
223 | ||
538950a1 | 224 | prog = rcu_dereference(reuse->prog); |
ef456144 CG |
225 | socks = READ_ONCE(reuse->num_socks); |
226 | if (likely(socks)) { | |
227 | /* paired with smp_wmb() in reuseport_add_sock() */ | |
228 | smp_rmb(); | |
229 | ||
538950a1 CG |
230 | if (prog && skb) |
231 | sk2 = run_bpf(reuse, socks, prog, skb, hdr_len); | |
232 | else | |
233 | sk2 = reuse->socks[reciprocal_scale(hash, socks)]; | |
ef456144 CG |
234 | } |
235 | ||
236 | out: | |
237 | rcu_read_unlock(); | |
238 | return sk2; | |
239 | } | |
240 | EXPORT_SYMBOL(reuseport_select_sock); | |
538950a1 CG |
241 | |
242 | struct bpf_prog * | |
243 | reuseport_attach_prog(struct sock *sk, struct bpf_prog *prog) | |
244 | { | |
245 | struct sock_reuseport *reuse; | |
246 | struct bpf_prog *old_prog; | |
247 | ||
248 | spin_lock_bh(&reuseport_lock); | |
249 | reuse = rcu_dereference_protected(sk->sk_reuseport_cb, | |
250 | lockdep_is_held(&reuseport_lock)); | |
251 | old_prog = rcu_dereference_protected(reuse->prog, | |
252 | lockdep_is_held(&reuseport_lock)); | |
253 | rcu_assign_pointer(reuse->prog, prog); | |
254 | spin_unlock_bh(&reuseport_lock); | |
255 | ||
256 | return old_prog; | |
257 | } | |
258 | EXPORT_SYMBOL(reuseport_attach_prog); |