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net: add sock_set_rcvbuf

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Add a helper to directly set the SO_RCVBUFFORCE sockopt from kernel space
without going through a fake uaccess.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Christoph Hellwig
2020-05-28 07:12:16 +02:00
committed by David S. Miller
parent ce3d9544ce
commit 26cfabf9cd
3 changed files with 34 additions and 33 deletions
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59
net/core/sock.c
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@ -789,6 +789,35 @@ void sock_set_keepalive(struct sock *sk)
}
EXPORT_SYMBOL(sock_set_keepalive);
static void __sock_set_rcvbuf(struct sock *sk, int val)
{
/* Ensure val * 2 fits into an int, to prevent max_t() from treating it
* as a negative value.
*/
val = min_t(int, val, INT_MAX / 2);
sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
/* We double it on the way in to account for "struct sk_buff" etc.
* overhead. Applications assume that the SO_RCVBUF setting they make
* will allow that much actual data to be received on that socket.
*
* Applications are unaware that "struct sk_buff" and other overheads
* allocate from the receive buffer during socket buffer allocation.
*
* And after considering the possible alternatives, returning the value
* we actually used in getsockopt is the most desirable behavior.
*/
WRITE_ONCE(sk->sk_rcvbuf, max_t(int, val * 2, SOCK_MIN_RCVBUF));
}
void sock_set_rcvbuf(struct sock *sk, int val)
{
lock_sock(sk);
__sock_set_rcvbuf(sk, val);
release_sock(sk);
}
EXPORT_SYMBOL(sock_set_rcvbuf);
/*
* This is meant for all protocols to use and covers goings on
* at the socket level. Everything here is generic.
@ -885,30 +914,7 @@ set_sndbuf:
* play 'guess the biggest size' games. RCVBUF/SNDBUF
* are treated in BSD as hints
*/
val = min_t(u32, val, sysctl_rmem_max);
set_rcvbuf:
/* Ensure val * 2 fits into an int, to prevent max_t()
* from treating it as a negative value.
*/
val = min_t(int, val, INT_MAX / 2);
sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
/*
* We double it on the way in to account for
* "struct sk_buff" etc. overhead. Applications
* assume that the SO_RCVBUF setting they make will
* allow that much actual data to be received on that
* socket.
*
* Applications are unaware that "struct sk_buff" and
* other overheads allocate from the receive buffer
* during socket buffer allocation.
*
* And after considering the possible alternatives,
* returning the value we actually used in getsockopt
* is the most desirable behavior.
*/
WRITE_ONCE(sk->sk_rcvbuf,
max_t(int, val * 2, SOCK_MIN_RCVBUF));
__sock_set_rcvbuf(sk, min_t(u32, val, sysctl_rmem_max));
break;
case SO_RCVBUFFORCE:
@ -920,9 +926,8 @@ set_rcvbuf:
/* No negative values (to prevent underflow, as val will be
* multiplied by 2).
*/
if (val < 0)
val = 0;
goto set_rcvbuf;
__sock_set_rcvbuf(sk, max(val, 0));
break;
case SO_KEEPALIVE:
if (sk->sk_prot->keepalive)