netdev - [PATCH net-next 7/7] mptcp: restrict values of 'enabled' sysctl

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Message-Id: <20210527235430.183465-8-mathew.j.martineau@linux.intel.com>
Date:   Thu, 27 May 2021 16:54:30 -0700
From:   Mat Martineau <mathew.j.martineau@...ux.intel.com>
To:     netdev@...r.kernel.org
Cc:     Matthieu Baerts <matthieu.baerts@...sares.net>,
        davem@...emloft.net, kuba@...nel.org, mptcp@...ts.linux.dev,
        Florian Westphal <fw@...len.de>,
        Mat Martineau <mathew.j.martineau@...ux.intel.com>
Subject: [PATCH net-next 7/7] mptcp: restrict values of 'enabled' sysctl

From: Matthieu Baerts <matthieu.baerts@...sares.net>

To avoid confusions, it seems better to parse this sysctl parameter as a
boolean. We use it as a boolean, no need to parse an integer and bring
confusions if we see a value different from 0 and 1, especially with
this parameter name: enabled.

It seems fine to do this modification because the default value is 1
(enabled). Then the only other interesting value to set is 0 (disabled).
All other values would not have changed the default behaviour.

Suggested-by: Florian Westphal <fw@...len.de>
Acked-by: Florian Westphal <fw@...len.de>
Signed-off-by: Matthieu Baerts <matthieu.baerts@...sares.net>
Signed-off-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
---
 Documentation/networking/mptcp-sysctl.rst | 8 ++++----
 net/mptcp/ctrl.c                          | 8 +++++---
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst
index 6af0196c4297..3b352e5f6300 100644
--- a/Documentation/networking/mptcp-sysctl.rst
+++ b/Documentation/networking/mptcp-sysctl.rst
@@ -7,13 +7,13 @@ MPTCP Sysfs variables
 /proc/sys/net/mptcp/* Variables
 ===============================
 
-enabled - INTEGER
+enabled - BOOLEAN
 	Control whether MPTCP sockets can be created.
 
-	MPTCP sockets can be created if the value is nonzero. This is
-	a per-namespace sysctl.
+	MPTCP sockets can be created if the value is 1. This is a
+	per-namespace sysctl.
 
-	Default: 1
+	Default: 1 (enabled)
 
 add_addr_timeout - INTEGER (seconds)
 	Set the timeout after which an ADD_ADDR control message will be
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index a3b15ed60b77..1ec4d36a39f0 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -21,7 +21,7 @@ struct mptcp_pernet {
 	struct ctl_table_header *ctl_table_hdr;
 #endif
 
-	int mptcp_enabled;
+	u8 mptcp_enabled;
 	unsigned int add_addr_timeout;
 };
 
@@ -50,12 +50,14 @@ static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
 static struct ctl_table mptcp_sysctl_table[] = {
 	{
 		.procname = "enabled",
-		.maxlen = sizeof(int),
+		.maxlen = sizeof(u8),
 		.mode = 0644,
 		/* users with CAP_NET_ADMIN or root (not and) can change this
 		 * value, same as other sysctl or the 'net' tree.
 		 */
-		.proc_handler = proc_dointvec,
+		.proc_handler = proc_dou8vec_minmax,
+		.extra1       = SYSCTL_ZERO,
+		.extra2       = SYSCTL_ONE
 	},
 	{
 		.procname = "add_addr_timeout",
-- 
2.31.1