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/module.h> 15 #include <linux/slab.h> 16 #include <linux/types.h> 17 #include <linux/module.h> 18 #include <linux/string.h> 19 #include <linux/errno.h> 20 #include <linux/skbuff.h> 21 #include <linux/cgroup.h> 22 #include <linux/rcupdate.h> 23 #include <linux/atomic.h> 24 #include <linux/sched/task.h> 25 26 #include <net/rtnetlink.h> 27 #include <net/pkt_cls.h> 28 #include <net/sock.h> 29 #include <net/netprio_cgroup.h> 30 31 #include <linux/fdtable.h> 32 33 /* 34 * netprio allocates per-net_device priomap array which is indexed by 35 * css->id. Limiting css ID to 16bits doesn't lose anything. 36 */ 37 #define NETPRIO_ID_MAX USHRT_MAX 38 39 #define PRIOMAP_MIN_SZ 128 40 41 /* 42 * Extend @dev->priomap so that it's large enough to accommodate 43 * @target_idx. @dev->priomap.priomap_len > @target_idx after successful 44 * return. Must be called under rtnl lock. 45 */ 46 static int extend_netdev_table(struct net_device *dev, u32 target_idx) 47 { 48 struct netprio_map *old, *new; 49 size_t new_sz, new_len; 50 51 /* is the existing priomap large enough? */ 52 old = rtnl_dereference(dev->priomap); 53 if (old && old->priomap_len > target_idx) 54 return 0; 55 56 /* 57 * Determine the new size. Let's keep it power-of-two. We start 58 * from PRIOMAP_MIN_SZ and double it until it's large enough to 59 * accommodate @target_idx. 60 */ 61 new_sz = PRIOMAP_MIN_SZ; 62 while (true) { 63 new_len = (new_sz - offsetof(struct netprio_map, priomap)) / 64 sizeof(new->priomap[0]); 65 if (new_len > target_idx) 66 break; 67 new_sz *= 2; 68 /* overflowed? */ 69 if (WARN_ON(new_sz < PRIOMAP_MIN_SZ)) 70 return -ENOSPC; 71 } 72 73 /* allocate & copy */ 74 new = kzalloc(new_sz, GFP_KERNEL); 75 if (!new) 76 return -ENOMEM; 77 78 if (old) 79 memcpy(new->priomap, old->priomap, 80 old->priomap_len * sizeof(old->priomap[0])); 81 82 new->priomap_len = new_len; 83 84 /* install the new priomap */ 85 rcu_assign_pointer(dev->priomap, new); 86 if (old) 87 kfree_rcu(old, rcu); 88 return 0; 89 } 90 91 /** 92 * netprio_prio - return the effective netprio of a cgroup-net_device pair 93 * @css: css part of the target pair 94 * @dev: net_device part of the target pair 95 * 96 * Should be called under RCU read or rtnl lock. 97 */ 98 static u32 netprio_prio(struct cgroup_subsys_state *css, struct net_device *dev) 99 { 100 struct netprio_map *map = rcu_dereference_rtnl(dev->priomap); 101 int id = css->cgroup->id; 102 103 if (map && id < map->priomap_len) 104 return map->priomap[id]; 105 return 0; 106 } 107 108 /** 109 * netprio_set_prio - set netprio on a cgroup-net_device pair 110 * @css: css part of the target pair 111 * @dev: net_device part of the target pair 112 * @prio: prio to set 113 * 114 * Set netprio to @prio on @css-@dev pair. Should be called under rtnl 115 * lock and may fail under memory pressure for non-zero @prio. 116 */ 117 static int netprio_set_prio(struct cgroup_subsys_state *css, 118 struct net_device *dev, u32 prio) 119 { 120 struct netprio_map *map; 121 int id = css->cgroup->id; 122 int ret; 123 124 /* avoid extending priomap for zero writes */ 125 map = rtnl_dereference(dev->priomap); 126 if (!prio && (!map || map->priomap_len <= id)) 127 return 0; 128 129 ret = extend_netdev_table(dev, id); 130 if (ret) 131 return ret; 132 133 map = rtnl_dereference(dev->priomap); 134 map->priomap[id] = prio; 135 return 0; 136 } 137 138 static struct cgroup_subsys_state * 139 cgrp_css_alloc(struct cgroup_subsys_state *parent_css) 140 { 141 struct cgroup_subsys_state *css; 142 143 css = kzalloc(sizeof(*css), GFP_KERNEL); 144 if (!css) 145 return ERR_PTR(-ENOMEM); 146 147 return css; 148 } 149 150 static int cgrp_css_online(struct cgroup_subsys_state *css) 151 { 152 struct cgroup_subsys_state *parent_css = css->parent; 153 struct net_device *dev; 154 int ret = 0; 155 156 if (css->id > NETPRIO_ID_MAX) 157 return -ENOSPC; 158 159 if (!parent_css) 160 return 0; 161 162 rtnl_lock(); 163 /* 164 * Inherit prios from the parent. As all prios are set during 165 * onlining, there is no need to clear them on offline. 166 */ 167 for_each_netdev(&init_net, dev) { 168 u32 prio = netprio_prio(parent_css, dev); 169 170 ret = netprio_set_prio(css, dev, prio); 171 if (ret) 172 break; 173 } 174 rtnl_unlock(); 175 return ret; 176 } 177 178 static void cgrp_css_free(struct cgroup_subsys_state *css) 179 { 180 kfree(css); 181 } 182 183 static u64 read_prioidx(struct cgroup_subsys_state *css, struct cftype *cft) 184 { 185 return css->cgroup->id; 186 } 187 188 static int read_priomap(struct seq_file *sf, void *v) 189 { 190 struct net_device *dev; 191 192 rcu_read_lock(); 193 for_each_netdev_rcu(&init_net, dev) 194 seq_printf(sf, "%s %u\n", dev->name, 195 netprio_prio(seq_css(sf), dev)); 196 rcu_read_unlock(); 197 return 0; 198 } 199 200 static ssize_t write_priomap(struct kernfs_open_file *of, 201 char *buf, size_t nbytes, loff_t off) 202 { 203 char devname[IFNAMSIZ + 1]; 204 struct net_device *dev; 205 u32 prio; 206 int ret; 207 208 if (sscanf(buf, "%"__stringify(IFNAMSIZ)"s %u", devname, &prio) != 2) 209 return -EINVAL; 210 211 dev = dev_get_by_name(&init_net, devname); 212 if (!dev) 213 return -ENODEV; 214 215 cgroup_sk_alloc_disable(); 216 217 rtnl_lock(); 218 219 ret = netprio_set_prio(of_css(of), dev, prio); 220 221 rtnl_unlock(); 222 dev_put(dev); 223 return ret ?: nbytes; 224 } 225 226 static int update_netprio(const void *v, struct file *file, unsigned n) 227 { 228 int err; 229 struct socket *sock = sock_from_file(file, &err); 230 if (sock) { 231 spin_lock(&cgroup_sk_update_lock); 232 sock_cgroup_set_prioidx(&sock->sk->sk_cgrp_data, 233 (unsigned long)v); 234 spin_unlock(&cgroup_sk_update_lock); 235 } 236 return 0; 237 } 238 239 static void net_prio_attach(struct cgroup_taskset *tset) 240 { 241 struct task_struct *p; 242 struct cgroup_subsys_state *css; 243 244 cgroup_taskset_for_each(p, css, tset) { 245 void *v = (void *)(unsigned long)css->cgroup->id; 246 247 task_lock(p); 248 iterate_fd(p->files, 0, update_netprio, v); 249 task_unlock(p); 250 } 251 } 252 253 static struct cftype ss_files[] = { 254 { 255 .name = "prioidx", 256 .read_u64 = read_prioidx, 257 }, 258 { 259 .name = "ifpriomap", 260 .seq_show = read_priomap, 261 .write = write_priomap, 262 }, 263 { } /* terminate */ 264 }; 265 266 struct cgroup_subsys net_prio_cgrp_subsys = { 267 .css_alloc = cgrp_css_alloc, 268 .css_online = cgrp_css_online, 269 .css_free = cgrp_css_free, 270 .attach = net_prio_attach, 271 .legacy_cftypes = ss_files, 272 }; 273 274 static int netprio_device_event(struct notifier_block *unused, 275 unsigned long event, void *ptr) 276 { 277 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 278 struct netprio_map *old; 279 280 /* 281 * Note this is called with rtnl_lock held so we have update side 282 * protection on our rcu assignments 283 */ 284 285 switch (event) { 286 case NETDEV_UNREGISTER: 287 old = rtnl_dereference(dev->priomap); 288 RCU_INIT_POINTER(dev->priomap, NULL); 289 if (old) 290 kfree_rcu(old, rcu); 291 break; 292 } 293 return NOTIFY_DONE; 294 } 295 296 static struct notifier_block netprio_device_notifier = { 297 .notifier_call = netprio_device_event 298 }; 299 300 static int __init init_cgroup_netprio(void) 301 { 302 register_netdevice_notifier(&netprio_device_notifier); 303 return 0; 304 } 305 306 subsys_initcall(init_cgroup_netprio); 307 MODULE_LICENSE("GPL v2"); 308