1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * net/core/netprio_cgroup.c Priority Control Group 4 * 5 * Authors: Neil Horman <nhorman@tuxdriver.com> 6 */ 7 8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 9 10#include <linux/module.h> 11#include <linux/slab.h> 12#include <linux/types.h> 13#include <linux/string.h> 14#include <linux/errno.h> 15#include <linux/skbuff.h> 16#include <linux/cgroup.h> 17#include <linux/rcupdate.h> 18#include <linux/atomic.h> 19#include <linux/sched/task.h> 20 21#include <net/rtnetlink.h> 22#include <net/pkt_cls.h> 23#include <net/sock.h> 24#include <net/netprio_cgroup.h> 25 26#include <linux/fdtable.h> 27 28/* 29 * netprio allocates per-net_device priomap array which is indexed by 30 * css->id. Limiting css ID to 16bits doesn't lose anything. 31 */ 32#define NETPRIO_ID_MAX USHRT_MAX 33 34#define PRIOMAP_MIN_SZ 128 35 36/* 37 * Extend @dev->priomap so that it's large enough to accommodate 38 * @target_idx. @dev->priomap.priomap_len > @target_idx after successful 39 * return. Must be called under rtnl lock. 40 */ 41static int extend_netdev_table(struct net_device *dev, u32 target_idx) 42{ 43 struct netprio_map *old, *new; 44 size_t new_sz, new_len; 45 46 /* is the existing priomap large enough? */ 47 old = rtnl_dereference(dev->priomap); 48 if (old && old->priomap_len > target_idx) 49 return 0; 50 51 /* 52 * Determine the new size. Let's keep it power-of-two. We start 53 * from PRIOMAP_MIN_SZ and double it until it's large enough to 54 * accommodate @target_idx. 55 */ 56 new_sz = PRIOMAP_MIN_SZ; 57 while (true) { 58 new_len = (new_sz - offsetof(struct netprio_map, priomap)) / 59 sizeof(new->priomap[0]); 60 if (new_len > target_idx) 61 break; 62 new_sz *= 2; 63 /* overflowed? */ 64 if (WARN_ON(new_sz < PRIOMAP_MIN_SZ)) 65 return -ENOSPC; 66 } 67 68 /* allocate & copy */ 69 new = kzalloc(new_sz, GFP_KERNEL); 70 if (!new) 71 return -ENOMEM; 72 73 if (old) 74 memcpy(new->priomap, old->priomap, 75 old->priomap_len * sizeof(old->priomap[0])); 76 77 new->priomap_len = new_len; 78 79 /* install the new priomap */ 80 rcu_assign_pointer(dev->priomap, new); 81 if (old) 82 kfree_rcu(old, rcu); 83 return 0; 84} 85 86/** 87 * netprio_prio - return the effective netprio of a cgroup-net_device pair 88 * @css: css part of the target pair 89 * @dev: net_device part of the target pair 90 * 91 * Should be called under RCU read or rtnl lock. 92 */ 93static u32 netprio_prio(struct cgroup_subsys_state *css, struct net_device *dev) 94{ 95 struct netprio_map *map = rcu_dereference_rtnl(dev->priomap); 96 int id = css->id; 97 98 if (map && id < map->priomap_len) 99 return map->priomap[id]; 100 return 0; 101} 102 103/** 104 * netprio_set_prio - set netprio on a cgroup-net_device pair 105 * @css: css part of the target pair 106 * @dev: net_device part of the target pair 107 * @prio: prio to set 108 * 109 * Set netprio to @prio on @css-@dev pair. Should be called under rtnl 110 * lock and may fail under memory pressure for non-zero @prio. 111 */ 112static int netprio_set_prio(struct cgroup_subsys_state *css, 113 struct net_device *dev, u32 prio) 114{ 115 struct netprio_map *map; 116 int id = css->id; 117 int ret; 118 119 /* avoid extending priomap for zero writes */ 120 map = rtnl_dereference(dev->priomap); 121 if (!prio && (!map || map->priomap_len <= id)) 122 return 0; 123 124 ret = extend_netdev_table(dev, id); 125 if (ret) 126 return ret; 127 128 map = rtnl_dereference(dev->priomap); 129 map->priomap[id] = prio; 130 return 0; 131} 132 133static struct cgroup_subsys_state * 134cgrp_css_alloc(struct cgroup_subsys_state *parent_css) 135{ 136 struct cgroup_subsys_state *css; 137 138 css = kzalloc(sizeof(*css), GFP_KERNEL); 139 if (!css) 140 return ERR_PTR(-ENOMEM); 141 142 return css; 143} 144 145static int cgrp_css_online(struct cgroup_subsys_state *css) 146{ 147 struct cgroup_subsys_state *parent_css = css->parent; 148 struct net_device *dev; 149 int ret = 0; 150 151 if (css->id > NETPRIO_ID_MAX) 152 return -ENOSPC; 153 154 if (!parent_css) 155 return 0; 156 157 rtnl_lock(); 158 /* 159 * Inherit prios from the parent. As all prios are set during 160 * onlining, there is no need to clear them on offline. 161 */ 162 for_each_netdev(&init_net, dev) { 163 u32 prio = netprio_prio(parent_css, dev); 164 165 ret = netprio_set_prio(css, dev, prio); 166 if (ret) 167 break; 168 } 169 rtnl_unlock(); 170 return ret; 171} 172 173static void cgrp_css_free(struct cgroup_subsys_state *css) 174{ 175 kfree(css); 176} 177 178static u64 read_prioidx(struct cgroup_subsys_state *css, struct cftype *cft) 179{ 180 return css->id; 181} 182 183static int read_priomap(struct seq_file *sf, void *v) 184{ 185 struct net_device *dev; 186 187 rcu_read_lock(); 188 for_each_netdev_rcu(&init_net, dev) 189 seq_printf(sf, "%s %u\n", dev->name, 190 netprio_prio(seq_css(sf), dev)); 191 rcu_read_unlock(); 192 return 0; 193} 194 195static ssize_t write_priomap(struct kernfs_open_file *of, 196 char *buf, size_t nbytes, loff_t off) 197{ 198 char devname[IFNAMSIZ + 1]; 199 struct net_device *dev; 200 u32 prio; 201 int ret; 202 203 if (sscanf(buf, "%"__stringify(IFNAMSIZ)"s %u", devname, &prio) != 2) 204 return -EINVAL; 205 206 dev = dev_get_by_name(&init_net, devname); 207 if (!dev) 208 return -ENODEV; 209 210 rtnl_lock(); 211 212 ret = netprio_set_prio(of_css(of), dev, prio); 213 214 rtnl_unlock(); 215 dev_put(dev); 216 return ret ?: nbytes; 217} 218 219static int update_netprio(const void *v, struct file *file, unsigned n) 220{ 221 struct socket *sock = sock_from_file(file); 222 223 if (sock) 224 sock_cgroup_set_prioidx(&sock->sk->sk_cgrp_data, 225 (unsigned long)v); 226 return 0; 227} 228 229static void net_prio_attach(struct cgroup_taskset *tset) 230{ 231 struct task_struct *p; 232 struct cgroup_subsys_state *css; 233 234 cgroup_taskset_for_each(p, css, tset) { 235 void *v = (void *)(unsigned long)css->id; 236 237 task_lock(p); 238 iterate_fd(p->files, 0, update_netprio, v); 239 task_unlock(p); 240 } 241} 242 243static struct cftype ss_files[] = { 244 { 245 .name = "prioidx", 246 .read_u64 = read_prioidx, 247 }, 248 { 249 .name = "ifpriomap", 250 .seq_show = read_priomap, 251 .write = write_priomap, 252 }, 253 { } /* terminate */ 254}; 255 256struct cgroup_subsys net_prio_cgrp_subsys = { 257 .css_alloc = cgrp_css_alloc, 258 .css_online = cgrp_css_online, 259 .css_free = cgrp_css_free, 260 .attach = net_prio_attach, 261 .legacy_cftypes = ss_files, 262}; 263 264static int netprio_device_event(struct notifier_block *unused, 265 unsigned long event, void *ptr) 266{ 267 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 268 struct netprio_map *old; 269 270 /* 271 * Note this is called with rtnl_lock held so we have update side 272 * protection on our rcu assignments 273 */ 274 275 switch (event) { 276 case NETDEV_UNREGISTER: 277 old = rtnl_dereference(dev->priomap); 278 RCU_INIT_POINTER(dev->priomap, NULL); 279 if (old) 280 kfree_rcu(old, rcu); 281 break; 282 } 283 return NOTIFY_DONE; 284} 285 286static struct notifier_block netprio_device_notifier = { 287 .notifier_call = netprio_device_event 288}; 289 290static int __init init_cgroup_netprio(void) 291{ 292 register_netdevice_notifier(&netprio_device_notifier); 293 return 0; 294} 295subsys_initcall(init_cgroup_netprio); 296