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/* drivers/misc/uid_stat.c
*
* Copyright (C) 2008 - 2009 Google, Inc.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <asm/atomic.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/proc_fs.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stat.h>
#include <linux/uid_stat.h>
static DEFINE_SPINLOCK(uid_lock);
static LIST_HEAD(uid_list);
static struct proc_dir_entry *parent;
struct uid_stat {
struct list_head link;
uid_t uid;
atomic_t tcp_rcv;
atomic_t tcp_snd;
};
static struct uid_stat *find_uid_stat(uid_t uid) {
unsigned long flags;
struct uid_stat *entry;
spin_lock_irqsave(&uid_lock, flags);
list_for_each_entry(entry, &uid_list, link) {
if (entry->uid == uid) {
spin_unlock_irqrestore(&uid_lock, flags);
return entry;
}
}
spin_unlock_irqrestore(&uid_lock, flags);
return NULL;
}
static int tcp_snd_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
int len;
unsigned int bytes;
char *p = page;
struct uid_stat *uid_entry = (struct uid_stat *) data;
if (!data)
return 0;
bytes = (unsigned int) (atomic_read(&uid_entry->tcp_snd) + INT_MIN);
p += sprintf(p, "%u\n", bytes);
len = (p - page) - off;
*eof = (len <= count) ? 1 : 0;
*start = page + off;
return len;
}
static int tcp_rcv_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
int len;
unsigned int bytes;
char *p = page;
struct uid_stat *uid_entry = (struct uid_stat *) data;
if (!data)
return 0;
bytes = (unsigned int) (atomic_read(&uid_entry->tcp_rcv) + INT_MIN);
p += sprintf(p, "%u\n", bytes);
len = (p - page) - off;
*eof = (len <= count) ? 1 : 0;
*start = page + off;
return len;
}
/* Create a new entry for tracking the specified uid. */
static struct uid_stat *create_stat(uid_t uid) {
unsigned long flags;
char uid_s[32];
struct uid_stat *new_uid;
struct proc_dir_entry *entry;
/* Create the uid stat struct and append it to the list. */
if ((new_uid = kmalloc(sizeof(struct uid_stat), GFP_KERNEL)) == NULL)
return NULL;
new_uid->uid = uid;
/* Counters start at INT_MIN, so we can track 4GB of network traffic. */
atomic_set(&new_uid->tcp_rcv, INT_MIN);
atomic_set(&new_uid->tcp_snd, INT_MIN);
spin_lock_irqsave(&uid_lock, flags);
list_add_tail(&new_uid->link, &uid_list);
spin_unlock_irqrestore(&uid_lock, flags);
sprintf(uid_s, "%d", uid);
entry = proc_mkdir(uid_s, parent);
/* Keep reference to uid_stat so we know what uid to read stats from. */
create_proc_read_entry("tcp_snd", S_IRUGO, entry , tcp_snd_read_proc,
(void *) new_uid);
create_proc_read_entry("tcp_rcv", S_IRUGO, entry, tcp_rcv_read_proc,
(void *) new_uid);
return new_uid;
}
int update_tcp_snd(uid_t uid, int size) {
struct uid_stat *entry;
if ((entry = find_uid_stat(uid)) == NULL &&
((entry = create_stat(uid)) == NULL)) {
return -1;
}
atomic_add(size, &entry->tcp_snd);
return 0;
}
int update_tcp_rcv(uid_t uid, int size) {
struct uid_stat *entry;
if ((entry = find_uid_stat(uid)) == NULL &&
((entry = create_stat(uid)) == NULL)) {
return -1;
}
atomic_add(size, &entry->tcp_rcv);
return 0;
}
static int __init uid_stat_init(void)
{
parent = proc_mkdir("uid_stat", NULL);
if (!parent) {
pr_err("uid_stat: failed to create proc entry\n");
return -1;
}
return 0;
}
__initcall(uid_stat_init);
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