net/core/netclassid_cgroup.c

   1 /*
   2  * net/core/netclassid_cgroup.c Classid Cgroupfs Handling
   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:     Thomas Graf <tgraf@suug.ch>
  10  */
  11
  12 #include <linux/slab.h>
  13 #include <linux/cgroup.h>
  14 #include <linux/fdtable.h>
  15 #include <linux/sched/task.h>
  16
  17 #include <net/cls_cgroup.h>
  18 #include <net/sock.h>
  19
  20 static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css)
  21 {
  22         return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
  23 }
  24
  25 struct cgroup_cls_state *task_cls_state(struct task_struct *p)
  26 {
  27         return css_cls_state(task_css_check(p, net_cls_cgrp_id,
  28                                             rcu_read_lock_bh_held()));
  29 }
  30 EXPORT_SYMBOL_GPL(task_cls_state);
  31
  32 static struct cgroup_subsys_state *
  33 cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
  34 {
  35         struct cgroup_cls_state *cs;
  36
  37         cs = kzalloc(sizeof(*cs), GFP_KERNEL);
  38         if (!cs)
  39                 return ERR_PTR(-ENOMEM);
  40
  41         return &cs->css;
  42 }
  43
  44 static int cgrp_css_online(struct cgroup_subsys_state *css)
  45 {
  46         struct cgroup_cls_state *cs = css_cls_state(css);
  47         struct cgroup_cls_state *parent = css_cls_state(css->parent);
  48
  49         if (parent)
  50                 cs->classid = parent->classid;
  51
  52         return 0;
  53 }
  54
  55 static void cgrp_css_free(struct cgroup_subsys_state *css)
  56 {
  57         kfree(css_cls_state(css));
  58 }
  59
  60 /*
  61  * To avoid freezing of sockets creation for tasks with big number of threads
  62  * and opened sockets lets release file_lock every 1000 iterated descriptors.
  63  * New sockets will already have been created with new classid.
  64  */
  65
  66 struct update_classid_context {
  67         u32 classid;
  68         unsigned int batch;
  69 };
  70
  71 #define UPDATE_CLASSID_BATCH 1000
  72
  73 static int update_classid_sock(const void *v, struct file *file, unsigned n)
  74 {
  75         int err;
  76         struct update_classid_context *ctx = (void *)v;
  77         struct socket *sock = sock_from_file(file, &err);
  78
  79         if (sock) {
  80                 spin_lock(&cgroup_sk_update_lock);
  81                 sock_cgroup_set_classid(&sock->sk->sk_cgrp_data, ctx->classid);
  82                 spin_unlock(&cgroup_sk_update_lock);
  83         }
  84         if (--ctx->batch == 0) {
  85                 ctx->batch = UPDATE_CLASSID_BATCH;
  86                 return n + 1;
  87         }
  88         return 0;
  89 }
  90
  91 static void update_classid_task(struct task_struct *p, u32 classid)
  92 {
  93         struct update_classid_context ctx = {
  94                 .classid = classid,
  95                 .batch = UPDATE_CLASSID_BATCH
  96         };
  97         unsigned int fd = 0;
  98
  99         do {
 100                 task_lock(p);
 101                 fd = iterate_fd(p->files, fd, update_classid_sock, &ctx);
 102                 task_unlock(p);
 103                 cond_resched();
 104         } while (fd);
 105 }
 106
 107 static void cgrp_attach(struct cgroup_taskset *tset)
 108 {
 109         struct cgroup_subsys_state *css;
 110         struct task_struct *p;
 111
 112         cgroup_taskset_for_each(p, css, tset) {
 113                 update_classid_task(p, css_cls_state(css)->classid);
 114         }
 115 }
 116
 117 static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
 118 {
 119         return css_cls_state(css)->classid;
 120 }
 121
 122 static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
 123                          u64 value)
 124 {
 125         struct cgroup_cls_state *cs = css_cls_state(css);
 126         struct css_task_iter it;
 127         struct task_struct *p;
 128
 129         cgroup_sk_alloc_disable();
 130
 131         cs->classid = (u32)value;
 132
 133         css_task_iter_start(css, 0, &it);
 134         while ((p = css_task_iter_next(&it)))
 135                 update_classid_task(p, cs->classid);
 136         css_task_iter_end(&it);
 137
 138         return 0;
 139 }
 140
 141 static struct cftype ss_files[] = {
 142         {
 143                 .name           = "classid",
 144                 .read_u64       = read_classid,
 145                 .write_u64      = write_classid,
 146         },
 147         { }     /* terminate */
 148 };
 149
 150 struct cgroup_subsys net_cls_cgrp_subsys = {
 151         .css_alloc              = cgrp_css_alloc,
 152         .css_online             = cgrp_css_online,
 153         .css_free               = cgrp_css_free,
 154         .attach                 = cgrp_attach,
 155         .legacy_cftypes         = ss_files,
 156 };