[PATCH 23/33] ipv4: add ip_sock_set_mtu_discover

Christoph Hellwig
2020-05-20T19:58:37Z

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

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com> [rxrpc bits]
---
include/net/ip.h | 1 +
net/ipv4/ip_sockglue.c | 11 +++++++++++
net/rxrpc/local_object.c | 8 +-------
net/rxrpc/output.c | 14 +++++---------
4 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/include/net/ip.h b/include/net/ip.h
index f063a491b9063..d3649c49dd333 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -766,6 +766,7 @@ static inline bool inetdev_valid_mtu(unsigned int mtu)
}

void ip_sock_set_freebind(struct sock *sk);
+int ip_sock_set_mtu_discover(struct sock *sk, int val);
void ip_sock_set_recverr(struct sock *sk);
void ip_sock_set_tos(struct sock *sk, int val);

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 9a6a65b66f9d3..a3c46ec95a756 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -597,6 +597,17 @@ void ip_sock_set_recverr(struct sock *sk)
}
EXPORT_SYMBOL(ip_sock_set_recverr);

+int ip_sock_set_mtu_discover(struct sock *sk, int val)
+{
+ if (val < IP_PMTUDISC_DONT || val > IP_PMTUDISC_OMIT)
+ return -EINVAL;
+ lock_sock(sk);
+ inet_sk(sk)->pmtudisc = val;
+ release_sock(sk);
+ return 0;
+}
+EXPORT_SYMBOL(ip_sock_set_mtu_discover);
+
/*
* Socket option code for IP. This is the end of the line after any
* TCP,UDP etc options on an IP socket.
diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
index 4c0e8fe5ec1fb..6f4e6b4817cf2 100644
--- a/net/rxrpc/local_object.c
+++ b/net/rxrpc/local_object.c
@@ -174,13 +174,7 @@ static int rxrpc_open_socket(struct rxrpc_local *local, struct net *net)
ip_sock_set_recverr(local->socket->sk);

/* we want to set the don't fragment bit */
- opt = IP_PMTUDISC_DO;
- ret = kernel_setsockopt(local->socket, SOL_IP, IP_MTU_DISCOVER,
- (char *) &opt, sizeof(opt));
- if (ret < 0) {
- _debug("setsockopt failed");
- goto error;
- }
+ ip_sock_set_mtu_discover(local->socket->sk, IP_PMTUDISC_DO);

/* We want receive timestamps. */
sock_enable_timestamps(local->socket->sk);
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index 90e263c6aa69e..ad0234e1e1713 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -321,7 +321,7 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb,
struct kvec iov[2];
rxrpc_serial_t serial;
size_t len;
- int ret, opt;
+ int ret;

_enter(",{%d}", skb->len);

@@ -476,18 +476,14 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb,
switch (conn->params.local->srx.transport.family) {
case AF_INET6:
case AF_INET:
- opt = IP_PMTUDISC_DONT;
- kernel_setsockopt(conn->params.local->socket,
- SOL_IP, IP_MTU_DISCOVER,
- (char *)&opt, sizeof(opt));
+ ip_sock_set_mtu_discover(conn->params.local->socket->sk,
+ IP_PMTUDISC_DONT);
ret = kernel_sendmsg(conn->params.local->socket, &msg,
iov, 2, len);
conn->params.peer->last_tx_at = ktime_get_seconds();

- opt = IP_PMTUDISC_DO;
- kernel_setsockopt(conn->params.local->socket,
- SOL_IP, IP_MTU_DISCOVER,
- (char *)&opt, sizeof(opt));
+ ip_sock_set_mtu_discover(conn->params.local->socket->sk,
+ IP_PMTUDISC_DO);
break;

default:
--
2.26.2