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 PRIOIDX_SZ 128
  31
  32 static unsigned long prioidx_map[PRIOIDX_SZ];
  33 static DEFINE_SPINLOCK(prioidx_map_lock);
  34 static atomic_t max_prioidx = ATOMIC_INIT(0);
  35
  36 static inline struct cgroup_netprio_state *cgrp_netprio_state(struct cgroup *cgrp)
  37 {
  38         return container_of(cgroup_subsys_state(cgrp, net_prio_subsys_id),
  39                             struct cgroup_netprio_state, css);
  40 }
  41
  42 static int get_prioidx(u32 *prio)
  43 {
  44         unsigned long flags;
  45         u32 prioidx;
  46
  47         spin_lock_irqsave(&prioidx_map_lock, flags);
  48         prioidx = find_first_zero_bit(prioidx_map, sizeof(unsigned long) * PRIOIDX_SZ);
  49         if (prioidx == sizeof(unsigned long) * PRIOIDX_SZ) {
  50                 spin_unlock_irqrestore(&prioidx_map_lock, flags);
  51                 return -ENOSPC;
  52         }
  53         set_bit(prioidx, prioidx_map);
  54         if (atomic_read(&max_prioidx) < prioidx)
  55                 atomic_set(&max_prioidx, prioidx);
  56         spin_unlock_irqrestore(&prioidx_map_lock, flags);
  57         *prio = prioidx;
  58         return 0;
  59 }
  60
  61 static void put_prioidx(u32 idx)
  62 {
  63         unsigned long flags;
  64
  65         spin_lock_irqsave(&prioidx_map_lock, flags);
  66         clear_bit(idx, prioidx_map);
  67         spin_unlock_irqrestore(&prioidx_map_lock, flags);
  68 }
  69
  70 static int extend_netdev_table(struct net_device *dev, u32 new_len)
  71 {
  72         size_t new_size = sizeof(struct netprio_map) +
  73                            ((sizeof(u32) * new_len));
  74         struct netprio_map *new_priomap = kzalloc(new_size, GFP_KERNEL);
  75         struct netprio_map *old_priomap;
  76
  77         old_priomap  = rtnl_dereference(dev->priomap);
  78
  79         if (!new_priomap) {
  80                 pr_warn("Unable to alloc new priomap!\n");
  81                 return -ENOMEM;
  82         }
  83
  84         if (old_priomap)
  85                 memcpy(new_priomap->priomap, old_priomap->priomap,
  86                        old_priomap->priomap_len *
  87                        sizeof(old_priomap->priomap[0]));
  88
  89         new_priomap->priomap_len = new_len;
  90
  91         rcu_assign_pointer(dev->priomap, new_priomap);
  92         if (old_priomap)
  93                 kfree_rcu(old_priomap, rcu);
  94         return 0;
  95 }
  96
  97 static int write_update_netdev_table(struct net_device *dev)
  98 {
  99         int ret = 0;
 100         u32 max_len;
 101         struct netprio_map *map;
 102
 103         max_len = atomic_read(&max_prioidx) + 1;
 104         map = rtnl_dereference(dev->priomap);
 105         if (!map || map->priomap_len < max_len)
 106                 ret = extend_netdev_table(dev, max_len);
 107
 108         return ret;
 109 }
 110
 111 static struct cgroup_subsys_state *cgrp_create(struct cgroup *cgrp)
 112 {
 113         struct cgroup_netprio_state *cs;
 114         int ret = -EINVAL;
 115
 116         cs = kzalloc(sizeof(*cs), GFP_KERNEL);
 117         if (!cs)
 118                 return ERR_PTR(-ENOMEM);
 119
 120         if (cgrp->parent && cgrp_netprio_state(cgrp->parent)->prioidx)
 121                 goto out;
 122
 123         ret = get_prioidx(&cs->prioidx);
 124         if (ret < 0) {
 125                 pr_warn("No space in priority index array\n");
 126                 goto out;
 127         }
 128
 129         return &cs->css;
 130 out:
 131         kfree(cs);
 132         return ERR_PTR(ret);
 133 }
 134
 135 static void cgrp_destroy(struct cgroup *cgrp)
 136 {
 137         struct cgroup_netprio_state *cs;
 138         struct net_device *dev;
 139         struct netprio_map *map;
 140
 141         cs = cgrp_netprio_state(cgrp);
 142         rtnl_lock();
 143         for_each_netdev(&init_net, dev) {
 144                 map = rtnl_dereference(dev->priomap);
 145                 if (map && cs->prioidx < map->priomap_len)
 146                         map->priomap[cs->prioidx] = 0;
 147         }
 148         rtnl_unlock();
 149         put_prioidx(cs->prioidx);
 150         kfree(cs);
 151 }
 152
 153 static u64 read_prioidx(struct cgroup *cgrp, struct cftype *cft)
 154 {
 155         return (u64)cgrp_netprio_state(cgrp)->prioidx;
 156 }
 157
 158 static int read_priomap(struct cgroup *cont, struct cftype *cft,
 159                         struct cgroup_map_cb *cb)
 160 {
 161         struct net_device *dev;
 162         u32 prioidx = cgrp_netprio_state(cont)->prioidx;
 163         u32 priority;
 164         struct netprio_map *map;
 165
 166         rcu_read_lock();
 167         for_each_netdev_rcu(&init_net, dev) {
 168                 map = rcu_dereference(dev->priomap);
 169                 priority = (map && prioidx < map->priomap_len) ? map->priomap[prioidx] : 0;
 170                 cb->fill(cb, dev->name, priority);
 171         }
 172         rcu_read_unlock();
 173         return 0;
 174 }
 175
 176 static int write_priomap(struct cgroup *cgrp, struct cftype *cft,
 177                          const char *buffer)
 178 {
 179         char *devname = kstrdup(buffer, GFP_KERNEL);
 180         int ret = -EINVAL;
 181         u32 prioidx = cgrp_netprio_state(cgrp)->prioidx;
 182         unsigned long priority;
 183         char *priostr;
 184         struct net_device *dev;
 185         struct netprio_map *map;
 186
 187         if (!devname)
 188                 return -ENOMEM;
 189
 190         /*
 191          * Minimally sized valid priomap string
 192          */
 193         if (strlen(devname) < 3)
 194                 goto out_free_devname;
 195
 196         priostr = strstr(devname, " ");
 197         if (!priostr)
 198                 goto out_free_devname;
 199
 200         /*
 201          *Separate the devname from the associated priority
 202          *and advance the priostr pointer to the priority value
 203          */
 204         *priostr = '\0';
 205         priostr++;
 206
 207         /*
 208          * If the priostr points to NULL, we're at the end of the passed
 209          * in string, and its not a valid write
 210          */
 211         if (*priostr == '\0')
 212                 goto out_free_devname;
 213
 214         ret = kstrtoul(priostr, 10, &priority);
 215         if (ret < 0)
 216                 goto out_free_devname;
 217
 218         ret = -ENODEV;
 219
 220         dev = dev_get_by_name(&init_net, devname);
 221         if (!dev)
 222                 goto out_free_devname;
 223
 224         rtnl_lock();
 225         ret = write_update_netdev_table(dev);
 226         if (ret < 0)
 227                 goto out_put_dev;
 228
 229         map = rtnl_dereference(dev->priomap);
 230         if (map)
 231                 map->priomap[prioidx] = priority;
 232
 233 out_put_dev:
 234         rtnl_unlock();
 235         dev_put(dev);
 236
 237 out_free_devname:
 238         kfree(devname);
 239         return ret;
 240 }
 241
 242 static int update_netprio(const void *v, struct file *file, unsigned n)
 243 {
 244         int err;
 245         struct socket *sock = sock_from_file(file, &err);
 246         if (sock)
 247                 sock->sk->sk_cgrp_prioidx = (u32)(unsigned long)v;
 248         return 0;
 249 }
 250
 251 static void net_prio_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 252 {
 253         struct task_struct *p;
 254         void *v;
 255
 256         cgroup_taskset_for_each(p, cgrp, tset) {
 257                 task_lock(p);
 258                 v = (void *)(unsigned long)task_netprioidx(p);
 259                 iterate_fd(p->files, 0, update_netprio, v);
 260                 task_unlock(p);
 261         }
 262 }
 263
 264 static struct cftype ss_files[] = {
 265         {
 266                 .name = "prioidx",
 267                 .read_u64 = read_prioidx,
 268         },
 269         {
 270                 .name = "ifpriomap",
 271                 .read_map = read_priomap,
 272                 .write_string = write_priomap,
 273         },
 274         { }     /* terminate */
 275 };
 276
 277 struct cgroup_subsys net_prio_subsys = {
 278         .name           = "net_prio",
 279         .create         = cgrp_create,
 280         .destroy        = cgrp_destroy,
 281         .attach         = net_prio_attach,
 282         .subsys_id      = net_prio_subsys_id,
 283         .base_cftypes   = ss_files,
 284         .module         = THIS_MODULE,
 285
 286         /*
 287          * net_prio has artificial limit on the number of cgroups and
 288          * disallows nesting making it impossible to co-mount it with other
 289          * hierarchical subsystems.  Remove the artificially low PRIOIDX_SZ
 290          * limit and properly nest configuration such that children follow
 291          * their parents' configurations by default and are allowed to
 292          * override and remove the following.
 293          */
 294         .broken_hierarchy = true,
 295 };
 296
 297 static int netprio_device_event(struct notifier_block *unused,
 298                                 unsigned long event, void *ptr)
 299 {
 300         struct net_device *dev = ptr;
 301         struct netprio_map *old;
 302
 303         /*
 304          * Note this is called with rtnl_lock held so we have update side
 305          * protection on our rcu assignments
 306          */
 307
 308         switch (event) {
 309         case NETDEV_UNREGISTER:
 310                 old = rtnl_dereference(dev->priomap);
 311                 RCU_INIT_POINTER(dev->priomap, NULL);
 312                 if (old)
 313                         kfree_rcu(old, rcu);
 314                 break;
 315         }
 316         return NOTIFY_DONE;
 317 }
 318
 319 static struct notifier_block netprio_device_notifier = {
 320         .notifier_call = netprio_device_event
 321 };
 322
 323 static int __init init_cgroup_netprio(void)
 324 {
 325         int ret;
 326
 327         ret = cgroup_load_subsys(&net_prio_subsys);
 328         if (ret)
 329                 goto out;
 330
 331         register_netdevice_notifier(&netprio_device_notifier);
 332
 333 out:
 334         return ret;
 335 }
 336
 337 static void __exit exit_cgroup_netprio(void)
 338 {
 339         struct netprio_map *old;
 340         struct net_device *dev;
 341
 342         unregister_netdevice_notifier(&netprio_device_notifier);
 343
 344         cgroup_unload_subsys(&net_prio_subsys);
 345
 346         rtnl_lock();
 347         for_each_netdev(&init_net, dev) {
 348                 old = rtnl_dereference(dev->priomap);
 349                 RCU_INIT_POINTER(dev->priomap, NULL);
 350                 if (old)
 351                         kfree_rcu(old, rcu);
 352         }
 353         rtnl_unlock();
 354 }
 355
 356 module_init(init_cgroup_netprio);
 357 module_exit(exit_cgroup_netprio);
 358 MODULE_LICENSE("GPL v2");