mptcp: only allow set existing scheduler for net.mptcp.scheduler

The current behavior is to accept any strings as inputs, this results in
an inconsistent result where an unexisting scheduler can be set:

  # sysctl -w net.mptcp.scheduler=notdefault
  net.mptcp.scheduler = notdefault

This patch changes this behavior by checking for existing scheduler
before accepting the input.

Fixes: e3b2870b6d22 ("mptcp: add a new sysctl scheduler")
Cc: stable@vger.kernel.org
Signed-off-by: Gregory Detal <gregory.detal@gmail.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Tested-by: Geliang Tang <geliang@kernel.org>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://lore.kernel.org/r/20240506-upstream-net-20240506-mptcp-sched-exist-v1-1-2ed1529e521e@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index 13fe0748dde83804daa160af50827dfc899fc426..2963ba84e2ee4baf55ad06568568c6605f1ba367 100644 (file)
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -96,6 +96,43 @@ static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
 }
 
 #ifdef CONFIG_SYSCTL
+static int mptcp_set_scheduler(const struct net *net, const char *name)
+{
+       struct mptcp_pernet *pernet = mptcp_get_pernet(net);
+       struct mptcp_sched_ops *sched;
+       int ret = 0;
+
+       rcu_read_lock();
+       sched = mptcp_sched_find(name);
+       if (sched)
+               strscpy(pernet->scheduler, name, MPTCP_SCHED_NAME_MAX);
+       else
+               ret = -ENOENT;
+       rcu_read_unlock();
+
+       return ret;
+}
+
+static int proc_scheduler(struct ctl_table *ctl, int write,
+                         void *buffer, size_t *lenp, loff_t *ppos)
+{
+       const struct net *net = current->nsproxy->net_ns;
+       char val[MPTCP_SCHED_NAME_MAX];
+       struct ctl_table tbl = {
+               .data = val,
+               .maxlen = MPTCP_SCHED_NAME_MAX,
+       };
+       int ret;
+
+       strscpy(val, mptcp_get_scheduler(net), MPTCP_SCHED_NAME_MAX);
+
+       ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
+       if (write && ret == 0)
+               ret = mptcp_set_scheduler(net, val);
+
+       return ret;
+}
+
 static struct ctl_table mptcp_sysctl_table[] = {
        {
                .procname = "enabled",
@@ -148,7 +185,7 @@ static struct ctl_table mptcp_sysctl_table[] = {
                .procname = "scheduler",
                .maxlen = MPTCP_SCHED_NAME_MAX,
                .mode = 0644,
-               .proc_handler = proc_dostring,
+               .proc_handler = proc_scheduler,
        },
        {
                .procname = "close_timeout",