1 /* 2 * net/core/netprio_cgroup.c Priority Control Group 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 7 * 2 of the License, or (at your option) any later version. 8 * 9 * Authors: Neil Horman <nhorman@tuxdriver.com> 10 */ 11 12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 13 14 #include <linux/slab.h> 15 #include <linux/types.h> 16 #include <linux/module.h> 17 #include <linux/string.h> 18 #include <linux/errno.h> 19 #include <linux/skbuff.h> 20 #include <linux/cgroup.h> 21 #include <linux/rcupdate.h> 22 #include <linux/atomic.h> 23 #include <linux/sched/task.h> 24 25 #include <net/rtnetlink.h> 26 #include <net/pkt_cls.h> 27 #include <net/sock.h> 28 #include <net/netprio_cgroup.h> 29 30 #include <linux/fdtable.h> 31 32 /* 33 * netprio allocates per-net_device priomap array which is indexed by 34 * css->id. Limiting css ID to 16bits doesn't lose anything. 35 */ 36 #define NETPRIO_ID_MAX USHRT_MAX 37 38 #define PRIOMAP_MIN_SZ 128 39 40 /* 41 * Extend @dev->priomap so that it's large enough to accommodate 42 * @target_idx. @dev->priomap.priomap_len > @target_idx after successful 43 * return. Must be called under rtnl lock. 44 */ 45 static int extend_netdev_table(struct net_device *dev, u32 target_idx) 46 { 47 struct netprio_map *old, *new; 48 size_t new_sz, new_len; 49 50 /* is the existing priomap large enough? */ 51 old = rtnl_dereference(dev->priomap); 52 if (old && old->priomap_len > target_idx) 53 return 0; 54 55 /* 56 * Determine the new size. Let's keep it power-of-two. We start 57 * from PRIOMAP_MIN_SZ and double it until it's large enough to 58 * accommodate @target_idx. 59 */ 60 new_sz = PRIOMAP_MIN_SZ; 61 while (true) { 62 new_len = (new_sz - offsetof(struct netprio_map, priomap)) / 63 sizeof(new->priomap[0]); 64 if (new_len > target_idx) 65 break; 66 new_sz *= 2; 67 /* overflowed? */ 68 if (WARN_ON(new_sz < PRIOMAP_MIN_SZ)) 69 return -ENOSPC; 70 } 71 72 /* allocate & copy */ 73 new = kzalloc(new_sz, GFP_KERNEL); 74 if (!new) 75 return -ENOMEM; 76 77 if (old) 78 memcpy(new->priomap, old->priomap, 79 old->priomap_len * sizeof(old->priomap[0])); 80 81 new->priomap_len = new_len; 82 83 /* install the new priomap */ 84 rcu_assign_pointer(dev->priomap, new); 85 if (old) 86 kfree_rcu(old, rcu); 87 return 0; 88 } 89 90 /** 91 * netprio_prio - return the effective netprio of a cgroup-net_device pair 92 * @css: css part of the target pair 93 * @dev: net_device part of the target pair 94 * 95 * Should be called under RCU read or rtnl lock. 96 */ 97 static u32 netprio_prio(struct cgroup_subsys_state *css, struct net_device *dev) 98 { 99 struct netprio_map *map = rcu_dereference_rtnl(dev->priomap); 100 int id = css->cgroup->id; 101 102 if (map && id < map->priomap_len) 103 return map->priomap[id]; 104 return 0; 105 } 106 107 /** 108 * netprio_set_prio - set netprio on a cgroup-net_device pair 109 * @css: css part of the target pair 110 * @dev: net_device part of the target pair 111 * @prio: prio to set 112 * 113 * Set netprio to @prio on @css-@dev pair. Should be called under rtnl 114 * lock and may fail under memory pressure for non-zero @prio. 115 */ 116 static int netprio_set_prio(struct cgroup_subsys_state *css, 117 struct net_device *dev, u32 prio) 118 { 119 struct netprio_map *map; 120 int id = css->cgroup->id; 121 int ret; 122 123 /* avoid extending priomap for zero writes */ 124 map = rtnl_dereference(dev->priomap); 125 if (!prio && (!map || map->priomap_len <= id)) 126 return 0; 127 128 ret = extend_netdev_table(dev, id); 129 if (ret) 130 return ret; 131 132 map = rtnl_dereference(dev->priomap); 133 map->priomap[id] = prio; 134 return 0; 135 } 136 137 static struct cgroup_subsys_state * 138 cgrp_css_alloc(struct cgroup_subsys_state *parent_css) 139 { 140 struct cgroup_subsys_state *css; 141 142 css = kzalloc(sizeof(*css), GFP_KERNEL); 143 if (!css) 144 return ERR_PTR(-ENOMEM); 145 146 return css; 147 } 148 149 static int cgrp_css_online(struct cgroup_subsys_state *css) 150 { 151 struct cgroup_subsys_state *parent_css = css->parent; 152 struct net_device *dev; 153 int ret = 0; 154 155 if (css->id > NETPRIO_ID_MAX) 156 return -ENOSPC; 157 158 if (!parent_css) 159 return 0; 160 161 rtnl_lock(); 162 /* 163 * Inherit prios from the parent. As all prios are set during 164 * onlining, there is no need to clear them on offline. 165 */ 166 for_each_netdev(&init_net, dev) { 167 u32 prio = netprio_prio(parent_css, dev); 168 169 ret = netprio_set_prio(css, dev, prio); 170 if (ret) 171 break; 172 } 173 rtnl_unlock(); 174 return ret; 175 } 176 177 static void cgrp_css_free(struct cgroup_subsys_state *css) 178 { 179 kfree(css); 180 } 181 182 static u64 read_prioidx(struct cgroup_subsys_state *css, struct cftype *cft) 183 { 184 return css->cgroup->id; 185 } 186 187 static int read_priomap(struct seq_file *sf, void *v) 188 { 189 struct net_device *dev; 190 191 rcu_read_lock(); 192 for_each_netdev_rcu(&init_net, dev) 193 seq_printf(sf, "%s %u\n", dev->name, 194 netprio_prio(seq_css(sf), dev)); 195 rcu_read_unlock(); 196 return 0; 197 } 198 199 static ssize_t write_priomap(struct kernfs_open_file *of, 200 char *buf, size_t nbytes, loff_t off) 201 { 202 char devname[IFNAMSIZ + 1]; 203 struct net_device *dev; 204 u32 prio; 205 int ret; 206 207 if (sscanf(buf, "%"__stringify(IFNAMSIZ)"s %u", devname, &prio) != 2) 208 return -EINVAL; 209 210 dev = dev_get_by_name(&init_net, devname); 211 if (!dev) 212 return -ENODEV; 213 214 cgroup_sk_alloc_disable(); 215 216 rtnl_lock(); 217 218 ret = netprio_set_prio(of_css(of), dev, prio); 219 220 rtnl_unlock(); 221 dev_put(dev); 222 return ret ?: nbytes; 223 } 224 225 static int update_netprio(const void *v, struct file *file, unsigned n) 226 { 227 int err; 228 struct socket *sock = sock_from_file(file, &err); 229 if (sock) { 230 spin_lock(&cgroup_sk_update_lock); 231 sock_cgroup_set_prioidx(&sock->sk->sk_cgrp_data, 232 (unsigned long)v); 233 spin_unlock(&cgroup_sk_update_lock); 234 } 235 return 0; 236 } 237 238 static void net_prio_attach(struct cgroup_taskset *tset) 239 { 240 struct task_struct *p; 241 struct cgroup_subsys_state *css; 242 243 cgroup_taskset_for_each(p, css, tset) { 244 void *v = (void *)(unsigned long)css->cgroup->id; 245 246 task_lock(p); 247 iterate_fd(p->files, 0, update_netprio, v); 248 task_unlock(p); 249 } 250 } 251 252 static struct cftype ss_files[] = { 253 { 254 .name = "prioidx", 255 .read_u64 = read_prioidx, 256 }, 257 { 258 .name = "ifpriomap", 259 .seq_show = read_priomap, 260 .write = write_priomap, 261 }, 262 { } /* terminate */ 263 }; 264 265 struct cgroup_subsys net_prio_cgrp_subsys = { 266 .css_alloc = cgrp_css_alloc, 267 .css_online = cgrp_css_online, 268 .css_free = cgrp_css_free, 269 .attach = net_prio_attach, 270 .legacy_cftypes = ss_files, 271 }; 272 273 static int netprio_device_event(struct notifier_block *unused, 274 unsigned long event, void *ptr) 275 { 276 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 277 struct netprio_map *old; 278 279 /* 280 * Note this is called with rtnl_lock held so we have update side 281 * protection on our rcu assignments 282 */ 283 284 switch (event) { 285 case NETDEV_UNREGISTER: 286 old = rtnl_dereference(dev->priomap); 287 RCU_INIT_POINTER(dev->priomap, NULL); 288 if (old) 289 kfree_rcu(old, rcu); 290 break; 291 } 292 return NOTIFY_DONE; 293 } 294 295 static struct notifier_block netprio_device_notifier = { 296 .notifier_call = netprio_device_event 297 }; 298 299 static int __init init_cgroup_netprio(void) 300 { 301 register_netdevice_notifier(&netprio_device_notifier); 302 return 0; 303 } 304 305 subsys_initcall(init_cgroup_netprio); 306 MODULE_LICENSE("GPL v2"); 307