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
find_uid_stat(uid_t uid)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
tcp_snd_read_proc(char * page,char ** start,off_t off,int count,int * eof,void * data)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
tcp_rcv_read_proc(char * page,char ** start,off_t off,int count,int * eof,void * data)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. */
create_stat(uid_t 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
update_tcp_snd(uid_t uid,int size)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
update_tcp_rcv(uid_t uid,int size)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
uid_stat_init(void)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);
154