net/core/netprio_cgroup.c

   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/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 <net/rtnetlink.h>
  24 #include <net/pkt_cls.h>
  25 #include <net/sock.h>
  26 #include <net/netprio_cgroup.h>
  27
  28 #include <linux/fdtable.h>
  29
  30 #define PRIOMAP_MIN_SZ          128
  31
  32 /*
  33  * Extend @dev->priomap so that it's large enough to accomodate
  34  * @target_idx.  @dev->priomap.priomap_len > @target_idx after successful
  35  * return.  Must be called under rtnl lock.
  36  */
  37 static int extend_netdev_table(struct net_device *dev, u32 target_idx)
  38 {
  39         struct netprio_map *old, *new;
  40         size_t new_sz, new_len;
  41
  42         /* is the existing priomap large enough? */
  43         old = rtnl_dereference(dev->priomap);
  44         if (old && old->priomap_len > target_idx)
  45                 return 0;
  46
  47         /*
  48          * Determine the new size.  Let's keep it power-of-two.  We start
  49          * from PRIOMAP_MIN_SZ and double it until it's large enough to
  50          * accommodate @target_idx.
  51          */
  52         new_sz = PRIOMAP_MIN_SZ;
  53         while (true) {
  54                 new_len = (new_sz - offsetof(struct netprio_map, priomap)) /
  55                         sizeof(new->priomap[0]);
  56                 if (new_len > target_idx)
  57                         break;
  58                 new_sz *= 2;
  59                 /* overflowed? */
  60                 if (WARN_ON(new_sz < PRIOMAP_MIN_SZ))
  61                         return -ENOSPC;
  62         }
  63
  64         /* allocate & copy */
  65         new = kzalloc(new_sz, GFP_KERNEL);
  66         if (!new)
  67                 return -ENOMEM;
  68
  69         if (old)
  70                 memcpy(new->priomap, old->priomap,
  71                        old->priomap_len * sizeof(old->priomap[0]));
  72
  73         new->priomap_len = new_len;
  74
  75         /* install the new priomap */
  76         rcu_assign_pointer(dev->priomap, new);
  77         if (old)
  78                 kfree_rcu(old, rcu);
  79         return 0;
  80 }
  81
  82 /**
  83  * netprio_prio - return the effective netprio of a cgroup-net_device pair
  84  * @css: css part of the target pair
  85  * @dev: net_device part of the target pair
  86  *
  87  * Should be called under RCU read or rtnl lock.
  88  */
  89 static u32 netprio_prio(struct cgroup_subsys_state *css, struct net_device *dev)
  90 {
  91         struct netprio_map *map = rcu_dereference_rtnl(dev->priomap);
  92         int id = css->cgroup->id;
  93
  94         if (map && id < map->priomap_len)
  95                 return map->priomap[id];
  96         return 0;
  97 }
  98
  99 /**
 100  * netprio_set_prio - set netprio on a cgroup-net_device pair
 101  * @css: css part of the target pair
 102  * @dev: net_device part of the target pair
 103  * @prio: prio to set
 104  *
 105  * Set netprio to @prio on @css-@dev pair.  Should be called under rtnl
 106  * lock and may fail under memory pressure for non-zero @prio.
 107  */
 108 static int netprio_set_prio(struct cgroup_subsys_state *css,
 109                             struct net_device *dev, u32 prio)
 110 {
 111         struct netprio_map *map;
 112         int id = css->cgroup->id;
 113         int ret;
 114
 115         /* avoid extending priomap for zero writes */
 116         map = rtnl_dereference(dev->priomap);
 117         if (!prio && (!map || map->priomap_len <= id))
 118                 return 0;
 119
 120         ret = extend_netdev_table(dev, id);
 121         if (ret)
 122                 return ret;
 123
 124         map = rtnl_dereference(dev->priomap);
 125         map->priomap[id] = prio;
 126         return 0;
 127 }
 128
 129 static struct cgroup_subsys_state *
 130 cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
 131 {
 132         struct cgroup_subsys_state *css;
 133
 134         css = kzalloc(sizeof(*css), GFP_KERNEL);
 135         if (!css)
 136                 return ERR_PTR(-ENOMEM);
 137
 138         return css;
 139 }
 140
 141 static int cgrp_css_online(struct cgroup_subsys_state *css)
 142 {
 143         struct cgroup_subsys_state *parent_css = css_parent(css);
 144         struct net_device *dev;
 145         int ret = 0;
 146
 147         if (!parent_css)
 148                 return 0;
 149
 150         rtnl_lock();
 151         /*
 152          * Inherit prios from the parent.  As all prios are set during
 153          * onlining, there is no need to clear them on offline.
 154          */
 155         for_each_netdev(&init_net, dev) {
 156                 u32 prio = netprio_prio(parent_css, dev);
 157
 158                 ret = netprio_set_prio(css, dev, prio);
 159                 if (ret)
 160                         break;
 161         }
 162         rtnl_unlock();
 163         return ret;
 164 }
 165
 166 static void cgrp_css_free(struct cgroup_subsys_state *css)
 167 {
 168         kfree(css);
 169 }
 170
 171 static u64 read_prioidx(struct cgroup *cgrp, struct cftype *cft)
 172 {
 173         return cgrp->id;
 174 }
 175
 176 static int read_priomap(struct cgroup *cont, struct cftype *cft,
 177                         struct cgroup_map_cb *cb)
 178 {
 179         struct cgroup_subsys_state *css = cgroup_css(cont, net_prio_subsys_id);
 180         struct net_device *dev;
 181
 182         rcu_read_lock();
 183         for_each_netdev_rcu(&init_net, dev)
 184                 cb->fill(cb, dev->name, netprio_prio(css, dev));
 185         rcu_read_unlock();
 186         return 0;
 187 }
 188
 189 static int write_priomap(struct cgroup *cgrp, struct cftype *cft,
 190                          const char *buffer)
 191 {
 192         struct cgroup_subsys_state *css = cgroup_css(cgrp, net_prio_subsys_id);
 193         char devname[IFNAMSIZ + 1];
 194         struct net_device *dev;
 195         u32 prio;
 196         int ret;
 197
 198         if (sscanf(buffer, "%"__stringify(IFNAMSIZ)"s %u", devname, &prio) != 2)
 199                 return -EINVAL;
 200
 201         dev = dev_get_by_name(&init_net, devname);
 202         if (!dev)
 203                 return -ENODEV;
 204
 205         rtnl_lock();
 206
 207         ret = netprio_set_prio(css, dev, prio);
 208
 209         rtnl_unlock();
 210         dev_put(dev);
 211         return ret;
 212 }
 213
 214 static int update_netprio(const void *v, struct file *file, unsigned n)
 215 {
 216         int err;
 217         struct socket *sock = sock_from_file(file, &err);
 218         if (sock)
 219                 sock->sk->sk_cgrp_prioidx = (u32)(unsigned long)v;
 220         return 0;
 221 }
 222
 223 static void net_prio_attach(struct cgroup_subsys_state *css,
 224                             struct cgroup_taskset *tset)
 225 {
 226         struct task_struct *p;
 227         void *v;
 228
 229         cgroup_taskset_for_each(p, css->cgroup, tset) {
 230                 task_lock(p);
 231                 v = (void *)(unsigned long)task_netprioidx(p);
 232                 iterate_fd(p->files, 0, update_netprio, v);
 233                 task_unlock(p);
 234         }
 235 }
 236
 237 static struct cftype ss_files[] = {
 238         {
 239                 .name = "prioidx",
 240                 .read_u64 = read_prioidx,
 241         },
 242         {
 243                 .name = "ifpriomap",
 244                 .read_map = read_priomap,
 245                 .write_string = write_priomap,
 246         },
 247         { }     /* terminate */
 248 };
 249
 250 struct cgroup_subsys net_prio_subsys = {
 251         .name           = "net_prio",
 252         .css_alloc      = cgrp_css_alloc,
 253         .css_online     = cgrp_css_online,
 254         .css_free       = cgrp_css_free,
 255         .attach         = net_prio_attach,
 256         .subsys_id      = net_prio_subsys_id,
 257         .base_cftypes   = ss_files,
 258         .module         = THIS_MODULE,
 259 };
 260
 261 static int netprio_device_event(struct notifier_block *unused,
 262                                 unsigned long event, void *ptr)
 263 {
 264         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 265         struct netprio_map *old;
 266
 267         /*
 268          * Note this is called with rtnl_lock held so we have update side
 269          * protection on our rcu assignments
 270          */
 271
 272         switch (event) {
 273         case NETDEV_UNREGISTER:
 274                 old = rtnl_dereference(dev->priomap);
 275                 RCU_INIT_POINTER(dev->priomap, NULL);
 276                 if (old)
 277                         kfree_rcu(old, rcu);
 278                 break;
 279         }
 280         return NOTIFY_DONE;
 281 }
 282
 283 static struct notifier_block netprio_device_notifier = {
 284         .notifier_call = netprio_device_event
 285 };
 286
 287 static int __init init_cgroup_netprio(void)
 288 {
 289         int ret;
 290
 291         ret = cgroup_load_subsys(&net_prio_subsys);
 292         if (ret)
 293                 goto out;
 294
 295         register_netdevice_notifier(&netprio_device_notifier);
 296
 297 out:
 298         return ret;
 299 }
 300
 301 static void __exit exit_cgroup_netprio(void)
 302 {
 303         struct netprio_map *old;
 304         struct net_device *dev;
 305
 306         unregister_netdevice_notifier(&netprio_device_notifier);
 307
 308         cgroup_unload_subsys(&net_prio_subsys);
 309
 310         rtnl_lock();
 311         for_each_netdev(&init_net, dev) {
 312                 old = rtnl_dereference(dev->priomap);
 313                 RCU_INIT_POINTER(dev->priomap, NULL);
 314                 if (old)
 315                         kfree_rcu(old, rcu);
 316         }
 317         rtnl_unlock();
 318 }
 319
 320 module_init(init_cgroup_netprio);
 321 module_exit(exit_cgroup_netprio);
 322 MODULE_LICENSE("GPL v2");