1 files changed, 302 insertions, 0 deletions
diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
new file mode 100644
index 000000000..9bd4cab7d
--- /dev/null
+++ b/net/core/netprio_cgroup.c
@@ -0,0 +1,302 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * net/core/netprio_cgroup.c	Priority Control Group
+ *
+ * Authors:	Neil Horman <nhorman@tuxdriver.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/skbuff.h>
+#include <linux/cgroup.h>
+#include <linux/rcupdate.h>
+#include <linux/atomic.h>
+#include <linux/sched/task.h>
+
+#include <net/rtnetlink.h>
+#include <net/pkt_cls.h>
+#include <net/sock.h>
+#include <net/netprio_cgroup.h>
+
+#include <linux/fdtable.h>
+
+/*
+ * netprio allocates per-net_device priomap array which is indexed by
+ * css->id.  Limiting css ID to 16bits doesn't lose anything.
+ */
+#define NETPRIO_ID_MAX		USHRT_MAX
+
+#define PRIOMAP_MIN_SZ		128
+
+/*
+ * Extend @dev->priomap so that it's large enough to accommodate
+ * @target_idx.  @dev->priomap.priomap_len > @target_idx after successful
+ * return.  Must be called under rtnl lock.
+ */
+static int extend_netdev_table(struct net_device *dev, u32 target_idx)
+{
+	struct netprio_map *old, *new;
+	size_t new_sz, new_len;
+
+	/* is the existing priomap large enough? */
+	old = rtnl_dereference(dev->priomap);
+	if (old && old->priomap_len > target_idx)
+		return 0;
+
+	/*
+	 * Determine the new size.  Let's keep it power-of-two.  We start
+	 * from PRIOMAP_MIN_SZ and double it until it's large enough to
+	 * accommodate @target_idx.
+	 */
+	new_sz = PRIOMAP_MIN_SZ;
+	while (true) {
+		new_len = (new_sz - offsetof(struct netprio_map, priomap)) /
+			sizeof(new->priomap[0]);
+		if (new_len > target_idx)
+			break;
+		new_sz *= 2;
+		/* overflowed? */
+		if (WARN_ON(new_sz < PRIOMAP_MIN_SZ))
+			return -ENOSPC;
+	}
+
+	/* allocate & copy */
+	new = kzalloc(new_sz, GFP_KERNEL);
+	if (!new)
+		return -ENOMEM;
+
+	if (old)
+		memcpy(new->priomap, old->priomap,
+		       old->priomap_len * sizeof(old->priomap[0]));
+
+	new->priomap_len = new_len;
+
+	/* install the new priomap */
+	rcu_assign_pointer(dev->priomap, new);
+	if (old)
+		kfree_rcu(old, rcu);
+	return 0;
+}
+
+/**
+ * netprio_prio - return the effective netprio of a cgroup-net_device pair
+ * @css: css part of the target pair
+ * @dev: net_device part of the target pair
+ *
+ * Should be called under RCU read or rtnl lock.
+ */
+static u32 netprio_prio(struct cgroup_subsys_state *css, struct net_device *dev)
+{
+	struct netprio_map *map = rcu_dereference_rtnl(dev->priomap);
+	int id = css->id;
+
+	if (map && id < map->priomap_len)
+		return map->priomap[id];
+	return 0;
+}
+
+/**
+ * netprio_set_prio - set netprio on a cgroup-net_device pair
+ * @css: css part of the target pair
+ * @dev: net_device part of the target pair
+ * @prio: prio to set
+ *
+ * Set netprio to @prio on @css-@dev pair.  Should be called under rtnl
+ * lock and may fail under memory pressure for non-zero @prio.
+ */
+static int netprio_set_prio(struct cgroup_subsys_state *css,
+			    struct net_device *dev, u32 prio)
+{
+	struct netprio_map *map;
+	int id = css->id;
+	int ret;
+
+	/* avoid extending priomap for zero writes */
+	map = rtnl_dereference(dev->priomap);
+	if (!prio && (!map || map->priomap_len <= id))
+		return 0;
+
+	ret = extend_netdev_table(dev, id);
+	if (ret)
+		return ret;
+
+	map = rtnl_dereference(dev->priomap);
+	map->priomap[id] = prio;
+	return 0;
+}
+
+static struct cgroup_subsys_state *
+cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+	struct cgroup_subsys_state *css;
+
+	css = kzalloc(sizeof(*css), GFP_KERNEL);
+	if (!css)
+		return ERR_PTR(-ENOMEM);
+
+	return css;
+}
+
+static int cgrp_css_online(struct cgroup_subsys_state *css)
+{
+	struct cgroup_subsys_state *parent_css = css->parent;
+	struct net_device *dev;
+	int ret = 0;
+
+	if (css->id > NETPRIO_ID_MAX)
+		return -ENOSPC;
+
+	if (!parent_css)
+		return 0;
+
+	rtnl_lock();
+	/*
+	 * Inherit prios from the parent.  As all prios are set during
+	 * onlining, there is no need to clear them on offline.
+	 */
+	for_each_netdev(&init_net, dev) {
+		u32 prio = netprio_prio(parent_css, dev);
+
+		ret = netprio_set_prio(css, dev, prio);
+		if (ret)
+			break;
+	}
+	rtnl_unlock();
+	return ret;
+}
+
+static void cgrp_css_free(struct cgroup_subsys_state *css)
+{
+	kfree(css);
+}
+
+static u64 read_prioidx(struct cgroup_subsys_state *css, struct cftype *cft)
+{
+	return css->id;
+}
+
+static int read_priomap(struct seq_file *sf, void *v)
+{
+	struct net_device *dev;
+
+	rcu_read_lock();
+	for_each_netdev_rcu(&init_net, dev)
+		seq_printf(sf, "%s %u\n", dev->name,
+			   netprio_prio(seq_css(sf), dev));
+	rcu_read_unlock();
+	return 0;
+}
+
+static ssize_t write_priomap(struct kernfs_open_file *of,
+			     char *buf, size_t nbytes, loff_t off)
+{
+	char devname[IFNAMSIZ + 1];
+	struct net_device *dev;
+	u32 prio;
+	int ret;
+
+	if (sscanf(buf, "%"__stringify(IFNAMSIZ)"s %u", devname, &prio) != 2)
+		return -EINVAL;
+
+	dev = dev_get_by_name(&init_net, devname);
+	if (!dev)
+		return -ENODEV;
+
+	cgroup_sk_alloc_disable();
+
+	rtnl_lock();
+
+	ret = netprio_set_prio(of_css(of), dev, prio);
+
+	rtnl_unlock();
+	dev_put(dev);
+	return ret ?: nbytes;
+}
+
+static int update_netprio(const void *v, struct file *file, unsigned n)
+{
+	int err;
+	struct socket *sock = sock_from_file(file, &err);
+	if (sock) {
+		spin_lock(&cgroup_sk_update_lock);
+		sock_cgroup_set_prioidx(&sock->sk->sk_cgrp_data,
+					(unsigned long)v);
+		spin_unlock(&cgroup_sk_update_lock);
+	}
+	return 0;
+}
+
+static void net_prio_attach(struct cgroup_taskset *tset)
+{
+	struct task_struct *p;
+	struct cgroup_subsys_state *css;
+
+	cgroup_sk_alloc_disable();
+
+	cgroup_taskset_for_each(p, css, tset) {
+		void *v = (void *)(unsigned long)css->id;
+
+		task_lock(p);
+		iterate_fd(p->files, 0, update_netprio, v);
+		task_unlock(p);
+	}
+}
+
+static struct cftype ss_files[] = {
+	{
+		.name = "prioidx",
+		.read_u64 = read_prioidx,
+	},
+	{
+		.name = "ifpriomap",
+		.seq_show = read_priomap,
+		.write = write_priomap,
+	},
+	{ }	/* terminate */
+};
+
+struct cgroup_subsys net_prio_cgrp_subsys = {
+	.css_alloc	= cgrp_css_alloc,
+	.css_online	= cgrp_css_online,
+	.css_free	= cgrp_css_free,
+	.attach		= net_prio_attach,
+	.legacy_cftypes	= ss_files,
+};
+
+static int netprio_device_event(struct notifier_block *unused,
+				unsigned long event, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct netprio_map *old;
+
+	/*
+	 * Note this is called with rtnl_lock held so we have update side
+	 * protection on our rcu assignments
+	 */
+
+	switch (event) {
+	case NETDEV_UNREGISTER:
+		old = rtnl_dereference(dev->priomap);
+		RCU_INIT_POINTER(dev->priomap, NULL);
+		if (old)
+			kfree_rcu(old, rcu);
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block netprio_device_notifier = {
+	.notifier_call = netprio_device_event
+};
+
+static int __init init_cgroup_netprio(void)
+{
+	register_netdevice_notifier(&netprio_device_notifier);
+	return 0;
+}
+subsys_initcall(init_cgroup_netprio);