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 accommodate
  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;
 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_subsys_state *css, struct cftype *cft)
 172 {
 173         return css->cgroup->id;
 174 }
 175
 176 static int read_priomap(struct seq_file *sf, void *v)
 177 {
 178         struct net_device *dev;
 179
 180         rcu_read_lock();
 181         for_each_netdev_rcu(&init_net, dev)
 182                 seq_printf(sf, "%s %u\n", dev->name,
 183                            netprio_prio(seq_css(sf), dev));
 184         rcu_read_unlock();
 185         return 0;
 186 }
 187
 188 static ssize_t write_priomap(struct kernfs_open_file *of,
 189                              char *buf, size_t nbytes, loff_t off)
 190 {
 191         char devname[IFNAMSIZ + 1];
 192         struct net_device *dev;
 193         u32 prio;
 194         int ret;
 195
 196         if (sscanf(buf, "%"__stringify(IFNAMSIZ)"s %u", devname, &prio) != 2)
 197                 return -EINVAL;
 198
 199         dev = dev_get_by_name(&init_net, devname);
 200         if (!dev)
 201                 return -ENODEV;
 202
 203         rtnl_lock();
 204
 205         ret = netprio_set_prio(of_css(of), dev, prio);
 206
 207         rtnl_unlock();
 208         dev_put(dev);
 209         return ret ?: nbytes;
 210 }
 211
 212 static int update_netprio(const void *v, struct file *file, unsigned n)
 213 {
 214         int err;
 215         struct socket *sock = sock_from_file(file, &err);
 216         if (sock)
 217                 sock->sk->sk_cgrp_prioidx = (u32)(unsigned long)v;
 218         return 0;
 219 }
 220
 221 static void net_prio_attach(struct cgroup_taskset *tset)
 222 {
 223         struct task_struct *p;
 224         struct cgroup_subsys_state *css;
 225
 226         cgroup_taskset_for_each(p, css, tset) {
 227                 void *v = (void *)(unsigned long)css->cgroup->id;
 228
 229                 task_lock(p);
 230                 iterate_fd(p->files, 0, update_netprio, v);
 231                 task_unlock(p);
 232         }
 233 }
 234
 235 static struct cftype ss_files[] = {
 236         {
 237                 .name = "prioidx",
 238                 .read_u64 = read_prioidx,
 239         },
 240         {
 241                 .name = "ifpriomap",
 242                 .seq_show = read_priomap,
 243                 .write = write_priomap,
 244         },
 245         { }     /* terminate */
 246 };
 247
 248 struct cgroup_subsys net_prio_cgrp_subsys = {
 249         .css_alloc      = cgrp_css_alloc,
 250         .css_online     = cgrp_css_online,
 251         .css_free       = cgrp_css_free,
 252         .attach         = net_prio_attach,
 253         .legacy_cftypes = ss_files,
 254 };
 255
 256 static int netprio_device_event(struct notifier_block *unused,
 257                                 unsigned long event, void *ptr)
 258 {
 259         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 260         struct netprio_map *old;
 261
 262         /*
 263          * Note this is called with rtnl_lock held so we have update side
 264          * protection on our rcu assignments
 265          */
 266
 267         switch (event) {
 268         case NETDEV_UNREGISTER:
 269                 old = rtnl_dereference(dev->priomap);
 270                 RCU_INIT_POINTER(dev->priomap, NULL);
 271                 if (old)
 272                         kfree_rcu(old, rcu);
 273                 break;
 274         }
 275         return NOTIFY_DONE;
 276 }
 277
 278 static struct notifier_block netprio_device_notifier = {
 279         .notifier_call = netprio_device_event
 280 };
 281
 282 static int __init init_cgroup_netprio(void)
 283 {
 284         register_netdevice_notifier(&netprio_device_notifier);
 285         return 0;
 286 }
 287
 288 subsys_initcall(init_cgroup_netprio);
 289 MODULE_LICENSE("GPL v2");