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2603c29e6c
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
59 lines
1.5 KiB
C
59 lines
1.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _SOCK_REUSEPORT_H
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#define _SOCK_REUSEPORT_H
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#include <linux/filter.h>
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#include <linux/skbuff.h>
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#include <linux/types.h>
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#include <linux/spinlock.h>
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#include <net/sock.h>
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extern spinlock_t reuseport_lock;
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struct sock_reuseport {
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struct rcu_head rcu;
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u16 max_socks; /* length of socks */
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u16 num_socks; /* elements in socks */
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/* The last synq overflow event timestamp of this
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* reuse->socks[] group.
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*/
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unsigned int synq_overflow_ts;
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/* ID stays the same even after the size of socks[] grows. */
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unsigned int reuseport_id;
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unsigned int bind_inany:1;
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unsigned int has_conns:1;
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struct bpf_prog __rcu *prog; /* optional BPF sock selector */
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struct sock *socks[]; /* array of sock pointers */
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};
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extern int reuseport_alloc(struct sock *sk, bool bind_inany);
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extern int reuseport_add_sock(struct sock *sk, struct sock *sk2,
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bool bind_inany);
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extern void reuseport_detach_sock(struct sock *sk);
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extern struct sock *reuseport_select_sock(struct sock *sk,
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u32 hash,
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struct sk_buff *skb,
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int hdr_len);
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extern int reuseport_attach_prog(struct sock *sk, struct bpf_prog *prog);
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extern int reuseport_detach_prog(struct sock *sk);
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static inline bool reuseport_has_conns(struct sock *sk, bool set)
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{
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struct sock_reuseport *reuse;
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bool ret = false;
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rcu_read_lock();
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reuse = rcu_dereference(sk->sk_reuseport_cb);
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if (reuse) {
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if (set)
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reuse->has_conns = 1;
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ret = reuse->has_conns;
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}
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rcu_read_unlock();
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return ret;
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}
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#endif /* _SOCK_REUSEPORT_H */
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