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