drivers/misc/uid_stat.c

   1 /* drivers/misc/uid_stat.c
   2  *
   3  * Copyright (C) 2008 - 2009 Google, Inc.
   4  *
   5  * This software is licensed under the terms of the GNU General Public
   6  * License version 2, as published by the Free Software Foundation, and
   7  * may be copied, distributed, and modified under those terms.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  */
  15
  16 #include <asm/atomic.h>
  17
  18 #include <linux/err.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/list.h>
  22 #include <linux/proc_fs.h>
  23 #include <linux/slab.h>
  24 #include <linux/spinlock.h>
  25 #include <linux/stat.h>
  26 #include <linux/uid_stat.h>
  27
  28 static DEFINE_SPINLOCK(uid_lock);
  29 static LIST_HEAD(uid_list);
  30 static struct proc_dir_entry *parent;
  31
  32 struct uid_stat {
  33         struct list_head link;
  34         uid_t uid;
  35         atomic_t tcp_rcv;
  36         atomic_t tcp_snd;
  37 };
  38
  39 static struct uid_stat *find_uid_stat(uid_t uid) {
  40         unsigned long flags;
  41         struct uid_stat *entry;
  42
  43         spin_lock_irqsave(&uid_lock, flags);
  44         list_for_each_entry(entry, &uid_list, link) {
  45                 if (entry->uid == uid) {
  46                         spin_unlock_irqrestore(&uid_lock, flags);
  47                         return entry;
  48                 }
  49         }
  50         spin_unlock_irqrestore(&uid_lock, flags);
  51         return NULL;
  52 }
  53
  54 static int tcp_snd_read_proc(char *page, char **start, off_t off,
  55                                 int count, int *eof, void *data)
  56 {
  57         int len;
  58         unsigned int bytes;
  59         char *p = page;
  60         struct uid_stat *uid_entry = (struct uid_stat *) data;
  61         if (!data)
  62                 return 0;
  63
  64         bytes = (unsigned int) (atomic_read(&uid_entry->tcp_snd) + INT_MIN);
  65         p += sprintf(p, "%u\n", bytes);
  66         len = (p - page) - off;
  67         *eof = (len <= count) ? 1 : 0;
  68         *start = page + off;
  69         return len;
  70 }
  71
  72 static int tcp_rcv_read_proc(char *page, char **start, off_t off,
  73                                 int count, int *eof, void *data)
  74 {
  75         int len;
  76         unsigned int bytes;
  77         char *p = page;
  78         struct uid_stat *uid_entry = (struct uid_stat *) data;
  79         if (!data)
  80                 return 0;
  81
  82         bytes = (unsigned int) (atomic_read(&uid_entry->tcp_rcv) + INT_MIN);
  83         p += sprintf(p, "%u\n", bytes);
  84         len = (p - page) - off;
  85         *eof = (len <= count) ? 1 : 0;
  86         *start = page + off;
  87         return len;
  88 }
  89
  90 /* Create a new entry for tracking the specified uid. */
  91 static struct uid_stat *create_stat(uid_t uid) {
  92         unsigned long flags;
  93         char uid_s[32];
  94         struct uid_stat *new_uid;
  95         struct proc_dir_entry *entry;
  96
  97         /* Create the uid stat struct and append it to the list. */
  98         if ((new_uid = kmalloc(sizeof(struct uid_stat), GFP_KERNEL)) == NULL)
  99                 return NULL;
 100
 101         new_uid->uid = uid;
 102         /* Counters start at INT_MIN, so we can track 4GB of network traffic. */
 103         atomic_set(&new_uid->tcp_rcv, INT_MIN);
 104         atomic_set(&new_uid->tcp_snd, INT_MIN);
 105
 106         spin_lock_irqsave(&uid_lock, flags);
 107         list_add_tail(&new_uid->link, &uid_list);
 108         spin_unlock_irqrestore(&uid_lock, flags);
 109
 110         sprintf(uid_s, "%d", uid);
 111         entry = proc_mkdir(uid_s, parent);
 112
 113         /* Keep reference to uid_stat so we know what uid to read stats from. */
 114         create_proc_read_entry("tcp_snd", S_IRUGO, entry , tcp_snd_read_proc,
 115                 (void *) new_uid);
 116
 117         create_proc_read_entry("tcp_rcv", S_IRUGO, entry, tcp_rcv_read_proc,
 118                 (void *) new_uid);
 119
 120         return new_uid;
 121 }
 122
 123 int update_tcp_snd(uid_t uid, int size) {
 124         struct uid_stat *entry;
 125         if ((entry = find_uid_stat(uid)) == NULL &&
 126                 ((entry = create_stat(uid)) == NULL)) {
 127                         return -1;
 128         }
 129         atomic_add(size, &entry->tcp_snd);
 130         return 0;
 131 }
 132
 133 int update_tcp_rcv(uid_t uid, int size) {
 134         struct uid_stat *entry;
 135         if ((entry = find_uid_stat(uid)) == NULL &&
 136                 ((entry = create_stat(uid)) == NULL)) {
 137                         return -1;
 138         }
 139         atomic_add(size, &entry->tcp_rcv);
 140         return 0;
 141 }
 142
 143 static int __init uid_stat_init(void)
 144 {
 145         parent = proc_mkdir("uid_stat", NULL);
 146         if (!parent) {
 147                 pr_err("uid_stat: failed to create proc entry\n");
 148                 return -1;
 149         }
 150         return 0;
 151 }
 152
 153 __initcall(uid_stat_init);