net/core/netprio_cgroup.c - linux - Git at Google

 // 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_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);
	// 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_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);