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git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - net/core/sock_reuseport.c
1 // SPDX-License-Identifier: GPL-2.0
3 * To speed up listener socket lookup, create an array to store all sockets
4 * listening on the same port. This allows a decision to be made after finding
5 * the first socket. An optional BPF program can also be configured for
6 * selecting the socket index from the array of available sockets.
9 #include <net/sock_reuseport.h>
10 #include <linux/bpf.h>
11 #include <linux/rcupdate.h>
13 #define INIT_SOCKS 128
15 static DEFINE_SPINLOCK(reuseport_lock
);
17 static struct sock_reuseport
*__reuseport_alloc(unsigned int max_socks
)
19 unsigned int size
= sizeof(struct sock_reuseport
) +
20 sizeof(struct sock
*) * max_socks
;
21 struct sock_reuseport
*reuse
= kzalloc(size
, GFP_ATOMIC
);
26 reuse
->max_socks
= max_socks
;
28 RCU_INIT_POINTER(reuse
->prog
, NULL
);
32 int reuseport_alloc(struct sock
*sk
)
34 struct sock_reuseport
*reuse
;
36 /* bh lock used since this function call may precede hlist lock in
37 * soft irq of receive path or setsockopt from process context
39 spin_lock_bh(&reuseport_lock
);
41 /* Allocation attempts can occur concurrently via the setsockopt path
42 * and the bind/hash path. Nothing to do when we lose the race.
44 if (rcu_dereference_protected(sk
->sk_reuseport_cb
,
45 lockdep_is_held(&reuseport_lock
)))
48 reuse
= __reuseport_alloc(INIT_SOCKS
);
50 spin_unlock_bh(&reuseport_lock
);
56 rcu_assign_pointer(sk
->sk_reuseport_cb
, reuse
);
59 spin_unlock_bh(&reuseport_lock
);
63 EXPORT_SYMBOL(reuseport_alloc
);
65 static struct sock_reuseport
*reuseport_grow(struct sock_reuseport
*reuse
)
67 struct sock_reuseport
*more_reuse
;
68 u32 more_socks_size
, i
;
70 more_socks_size
= reuse
->max_socks
* 2U;
71 if (more_socks_size
> U16_MAX
)
74 more_reuse
= __reuseport_alloc(more_socks_size
);
78 more_reuse
->max_socks
= more_socks_size
;
79 more_reuse
->num_socks
= reuse
->num_socks
;
80 more_reuse
->prog
= reuse
->prog
;
82 memcpy(more_reuse
->socks
, reuse
->socks
,
83 reuse
->num_socks
* sizeof(struct sock
*));
85 for (i
= 0; i
< reuse
->num_socks
; ++i
)
86 rcu_assign_pointer(reuse
->socks
[i
]->sk_reuseport_cb
,
89 /* Note: we use kfree_rcu here instead of reuseport_free_rcu so
90 * that reuse and more_reuse can temporarily share a reference
93 kfree_rcu(reuse
, rcu
);
98 * reuseport_add_sock - Add a socket to the reuseport group of another.
99 * @sk: New socket to add to the group.
100 * @sk2: Socket belonging to the existing reuseport group.
101 * May return ENOMEM and not add socket to group under memory pressure.
103 int reuseport_add_sock(struct sock
*sk
, struct sock
*sk2
)
105 struct sock_reuseport
*reuse
;
107 if (!rcu_access_pointer(sk2
->sk_reuseport_cb
)) {
108 int err
= reuseport_alloc(sk2
);
114 spin_lock_bh(&reuseport_lock
);
115 reuse
= rcu_dereference_protected(sk2
->sk_reuseport_cb
,
116 lockdep_is_held(&reuseport_lock
)),
117 WARN_ONCE(rcu_dereference_protected(sk
->sk_reuseport_cb
,
118 lockdep_is_held(&reuseport_lock
)),
119 "socket already in reuseport group");
121 if (reuse
->num_socks
== reuse
->max_socks
) {
122 reuse
= reuseport_grow(reuse
);
124 spin_unlock_bh(&reuseport_lock
);
129 reuse
->socks
[reuse
->num_socks
] = sk
;
130 /* paired with smp_rmb() in reuseport_select_sock() */
133 rcu_assign_pointer(sk
->sk_reuseport_cb
, reuse
);
135 spin_unlock_bh(&reuseport_lock
);
140 static void reuseport_free_rcu(struct rcu_head
*head
)
142 struct sock_reuseport
*reuse
;
144 reuse
= container_of(head
, struct sock_reuseport
, rcu
);
146 bpf_prog_destroy(reuse
->prog
);
150 void reuseport_detach_sock(struct sock
*sk
)
152 struct sock_reuseport
*reuse
;
155 spin_lock_bh(&reuseport_lock
);
156 reuse
= rcu_dereference_protected(sk
->sk_reuseport_cb
,
157 lockdep_is_held(&reuseport_lock
));
158 rcu_assign_pointer(sk
->sk_reuseport_cb
, NULL
);
160 for (i
= 0; i
< reuse
->num_socks
; i
++) {
161 if (reuse
->socks
[i
] == sk
) {
162 reuse
->socks
[i
] = reuse
->socks
[reuse
->num_socks
- 1];
164 if (reuse
->num_socks
== 0)
165 call_rcu(&reuse
->rcu
, reuseport_free_rcu
);
169 spin_unlock_bh(&reuseport_lock
);
171 EXPORT_SYMBOL(reuseport_detach_sock
);
173 static struct sock
*run_bpf(struct sock_reuseport
*reuse
, u16 socks
,
174 struct bpf_prog
*prog
, struct sk_buff
*skb
,
177 struct sk_buff
*nskb
= NULL
;
180 if (skb_shared(skb
)) {
181 nskb
= skb_clone(skb
, GFP_ATOMIC
);
187 /* temporarily advance data past protocol header */
188 if (!pskb_pull(skb
, hdr_len
)) {
192 index
= bpf_prog_run_save_cb(prog
, skb
);
193 __skb_push(skb
, hdr_len
);
200 return reuse
->socks
[index
];
204 * reuseport_select_sock - Select a socket from an SO_REUSEPORT group.
205 * @sk: First socket in the group.
206 * @hash: When no BPF filter is available, use this hash to select.
207 * @skb: skb to run through BPF filter.
208 * @hdr_len: BPF filter expects skb data pointer at payload data. If
209 * the skb does not yet point at the payload, this parameter represents
210 * how far the pointer needs to advance to reach the payload.
211 * Returns a socket that should receive the packet (or NULL on error).
213 struct sock
*reuseport_select_sock(struct sock
*sk
,
218 struct sock_reuseport
*reuse
;
219 struct bpf_prog
*prog
;
220 struct sock
*sk2
= NULL
;
224 reuse
= rcu_dereference(sk
->sk_reuseport_cb
);
226 /* if memory allocation failed or add call is not yet complete */
230 prog
= rcu_dereference(reuse
->prog
);
231 socks
= READ_ONCE(reuse
->num_socks
);
233 /* paired with smp_wmb() in reuseport_add_sock() */
237 sk2
= run_bpf(reuse
, socks
, prog
, skb
, hdr_len
);
239 sk2
= reuse
->socks
[reciprocal_scale(hash
, socks
)];
246 EXPORT_SYMBOL(reuseport_select_sock
);
249 reuseport_attach_prog(struct sock
*sk
, struct bpf_prog
*prog
)
251 struct sock_reuseport
*reuse
;
252 struct bpf_prog
*old_prog
;
254 spin_lock_bh(&reuseport_lock
);
255 reuse
= rcu_dereference_protected(sk
->sk_reuseport_cb
,
256 lockdep_is_held(&reuseport_lock
));
257 old_prog
= rcu_dereference_protected(reuse
->prog
,
258 lockdep_is_held(&reuseport_lock
));
259 rcu_assign_pointer(reuse
->prog
, prog
);
260 spin_unlock_bh(&reuseport_lock
);
264 EXPORT_SYMBOL(reuseport_attach_prog
);