1 /*
2 * xt_quota2 - enhanced xt_quota that can count upwards and in packets
3 * as a minimal accounting match.
4 * by Jan Engelhardt <jengelh@medozas.de>, 2008
5 *
6 * Originally based on xt_quota.c:
7 * netfilter module to enforce network quotas
8 * Sam Johnston <samj@samj.net>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License; either
12 * version 2 of the License, as published by the Free Software Foundation.
13 */
14 #include <linux/list.h>
15 #include <linux/module.h>
16 #include <linux/proc_fs.h>
17 #include <linux/skbuff.h>
18 #include <linux/spinlock.h>
19 #include <asm/atomic.h>
20 #include <net/netlink.h>
22 #include <linux/netfilter/x_tables.h>
23 #include <linux/netfilter/xt_quota2.h>
24 #ifdef CONFIG_NETFILTER_XT_MATCH_QUOTA2_LOG
25 #include <linux/netfilter_ipv4/ipt_ULOG.h>
26 #endif
28 /**
29 * @lock: lock to protect quota writers from each other
30 */
31 struct xt_quota_counter {
32 u_int64_t quota;
33 spinlock_t lock;
34 struct list_head list;
35 atomic_t ref;
36 char name[sizeof(((struct xt_quota_mtinfo2 *)NULL)->name)];
37 struct proc_dir_entry *procfs_entry;
38 };
40 #ifdef CONFIG_NETFILTER_XT_MATCH_QUOTA2_LOG
41 /* Harald's favorite number +1 :D From ipt_ULOG.C */
42 static int qlog_nl_event = 112;
43 module_param_named(event_num, qlog_nl_event, uint, S_IRUGO | S_IWUSR);
44 MODULE_PARM_DESC(event_num,
45 "Event number for NETLINK_NFLOG message. 0 disables log."
46 "111 is what ipt_ULOG uses.");
47 static struct sock *nflognl;
48 #endif
50 static LIST_HEAD(counter_list);
51 static DEFINE_SPINLOCK(counter_list_lock);
53 static struct proc_dir_entry *proc_xt_quota;
54 static unsigned int quota_list_perms = S_IRUGO | S_IWUSR;
55 static kuid_t quota_list_uid = KUIDT_INIT(0);
56 static kgid_t quota_list_gid = KGIDT_INIT(0);
57 module_param_named(perms, quota_list_perms, uint, S_IRUGO | S_IWUSR);
59 #ifdef CONFIG_NETFILTER_XT_MATCH_QUOTA2_LOG
60 static void quota2_log(unsigned int hooknum,
61 const struct sk_buff *skb,
62 const struct net_device *in,
63 const struct net_device *out,
64 const char *prefix)
65 {
66 ulog_packet_msg_t *pm;
67 struct sk_buff *log_skb;
68 size_t size;
69 struct nlmsghdr *nlh;
71 if (!qlog_nl_event)
72 return;
74 size = NLMSG_SPACE(sizeof(*pm));
75 size = max(size, (size_t)NLMSG_GOODSIZE);
76 log_skb = alloc_skb(size, GFP_ATOMIC);
77 if (!log_skb) {
78 pr_err("xt_quota2: cannot alloc skb for logging\n");
79 return;
80 }
82 nlh = nlmsg_put(log_skb, /*pid*/0, /*seq*/0, qlog_nl_event,
83 sizeof(*pm), 0);
84 if (!nlh) {
85 pr_err("xt_quota2: nlmsg_put failed\n");
86 kfree_skb(log_skb);
87 return;
88 }
89 pm = nlmsg_data(nlh);
90 if (skb->tstamp.tv64 == 0)
91 __net_timestamp((struct sk_buff *)skb);
92 pm->data_len = 0;
93 pm->hook = hooknum;
94 if (prefix != NULL)
95 strlcpy(pm->prefix, prefix, sizeof(pm->prefix));
96 else
97 *(pm->prefix) = '\0';
98 if (in)
99 strlcpy(pm->indev_name, in->name, sizeof(pm->indev_name));
100 else
101 pm->indev_name[0] = '\0';
103 if (out)
104 strlcpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
105 else
106 pm->outdev_name[0] = '\0';
108 NETLINK_CB(log_skb).dst_group = 1;
109 pr_debug("throwing 1 packets to netlink group 1\n");
110 netlink_broadcast(nflognl, log_skb, 0, 1, GFP_ATOMIC);
111 }
112 #else
113 static void quota2_log(unsigned int hooknum,
114 const struct sk_buff *skb,
115 const struct net_device *in,
116 const struct net_device *out,
117 const char *prefix)
118 {
119 }
120 #endif /* if+else CONFIG_NETFILTER_XT_MATCH_QUOTA2_LOG */
122 static ssize_t quota_proc_read(struct file *file, char __user *buf,
123 size_t size, loff_t *ppos)
124 {
125 struct xt_quota_counter *e = PDE_DATA(file_inode(file));
126 char tmp[24];
127 size_t tmp_size;
129 spin_lock_bh(&e->lock);
130 tmp_size = scnprintf(tmp, sizeof(tmp), "%llu\n", e->quota);
131 spin_unlock_bh(&e->lock);
132 return simple_read_from_buffer(buf, size, ppos, tmp, tmp_size);
133 }
135 static ssize_t quota_proc_write(struct file *file, const char __user *input,
136 size_t size, loff_t *ppos)
137 {
138 struct xt_quota_counter *e = PDE_DATA(file_inode(file));
139 char buf[sizeof("18446744073709551616")];
141 if (size > sizeof(buf))
142 size = sizeof(buf);
143 if (copy_from_user(buf, input, size) != 0)
144 return -EFAULT;
145 buf[sizeof(buf)-1] = '\0';
147 spin_lock_bh(&e->lock);
148 e->quota = simple_strtoull(buf, NULL, 0);
149 spin_unlock_bh(&e->lock);
150 return size;
151 }
153 static const struct file_operations q2_counter_fops = {
154 .read = quota_proc_read,
155 .write = quota_proc_write,
156 .llseek = default_llseek,
157 };
159 static struct xt_quota_counter *
160 q2_new_counter(const struct xt_quota_mtinfo2 *q, bool anon)
161 {
162 struct xt_quota_counter *e;
163 unsigned int size;
165 /* Do not need all the procfs things for anonymous counters. */
166 size = anon ? offsetof(typeof(*e), list) : sizeof(*e);
167 e = kmalloc(size, GFP_KERNEL);
168 if (e == NULL)
169 return NULL;
171 e->quota = q->quota;
172 spin_lock_init(&e->lock);
173 if (!anon) {
174 INIT_LIST_HEAD(&e->list);
175 atomic_set(&e->ref, 1);
176 strlcpy(e->name, q->name, sizeof(e->name));
177 }
178 return e;
179 }
181 /**
182 * q2_get_counter - get ref to counter or create new
183 * @name: name of counter
184 */
185 static struct xt_quota_counter *
186 q2_get_counter(const struct xt_quota_mtinfo2 *q)
187 {
188 struct proc_dir_entry *p;
189 struct xt_quota_counter *e = NULL;
190 struct xt_quota_counter *new_e;
192 if (*q->name == '\0')
193 return q2_new_counter(q, true);
195 /* No need to hold a lock while getting a new counter */
196 new_e = q2_new_counter(q, false);
197 if (new_e == NULL)
198 goto out;
200 spin_lock_bh(&counter_list_lock);
201 list_for_each_entry(e, &counter_list, list)
202 if (strcmp(e->name, q->name) == 0) {
203 atomic_inc(&e->ref);
204 spin_unlock_bh(&counter_list_lock);
205 kfree(new_e);
206 pr_debug("xt_quota2: old counter name=%s", e->name);
207 return e;
208 }
209 e = new_e;
210 pr_debug("xt_quota2: new_counter name=%s", e->name);
211 list_add_tail(&e->list, &counter_list);
212 /* The entry having a refcount of 1 is not directly destructible.
213 * This func has not yet returned the new entry, thus iptables
214 * has not references for destroying this entry.
215 * For another rule to try to destroy it, it would 1st need for this
216 * func* to be re-invoked, acquire a new ref for the same named quota.
217 * Nobody will access the e->procfs_entry either.
218 * So release the lock. */
219 spin_unlock_bh(&counter_list_lock);
221 /* create_proc_entry() is not spin_lock happy */
222 p = e->procfs_entry = proc_create_data(e->name, quota_list_perms,
223 proc_xt_quota, &q2_counter_fops, e);
225 if (IS_ERR_OR_NULL(p)) {
226 spin_lock_bh(&counter_list_lock);
227 list_del(&e->list);
228 spin_unlock_bh(&counter_list_lock);
229 goto out;
230 }
231 proc_set_user(p, quota_list_uid, quota_list_gid);
232 return e;
234 out:
235 kfree(e);
236 return NULL;
237 }
239 static int quota_mt2_check(const struct xt_mtchk_param *par)
240 {
241 struct xt_quota_mtinfo2 *q = par->matchinfo;
243 pr_debug("xt_quota2: check() flags=0x%04x", q->flags);
245 if (q->flags & ~XT_QUOTA_MASK)
246 return -EINVAL;
248 q->name[sizeof(q->name)-1] = '\0';
249 if (*q->name == '.' || strchr(q->name, '/') != NULL) {
250 printk(KERN_ERR "xt_quota.3: illegal name\n");
251 return -EINVAL;
252 }
254 q->master = q2_get_counter(q);
255 if (q->master == NULL) {
256 printk(KERN_ERR "xt_quota.3: memory alloc failure\n");
257 return -ENOMEM;
258 }
260 return 0;
261 }
263 static void quota_mt2_destroy(const struct xt_mtdtor_param *par)
264 {
265 struct xt_quota_mtinfo2 *q = par->matchinfo;
266 struct xt_quota_counter *e = q->master;
268 if (*q->name == '\0') {
269 kfree(e);
270 return;
271 }
273 spin_lock_bh(&counter_list_lock);
274 if (!atomic_dec_and_test(&e->ref)) {
275 spin_unlock_bh(&counter_list_lock);
276 return;
277 }
279 list_del(&e->list);
280 remove_proc_entry(e->name, proc_xt_quota);
281 spin_unlock_bh(&counter_list_lock);
282 kfree(e);
283 }
285 static bool
286 quota_mt2(const struct sk_buff *skb, struct xt_action_param *par)
287 {
288 struct xt_quota_mtinfo2 *q = (void *)par->matchinfo;
289 struct xt_quota_counter *e = q->master;
290 bool ret = q->flags & XT_QUOTA_INVERT;
292 spin_lock_bh(&e->lock);
293 if (q->flags & XT_QUOTA_GROW) {
294 /*
295 * While no_change is pointless in "grow" mode, we will
296 * implement it here simply to have a consistent behavior.
297 */
298 if (!(q->flags & XT_QUOTA_NO_CHANGE)) {
299 e->quota += (q->flags & XT_QUOTA_PACKET) ? 1 : skb->len;
300 }
301 ret = true;
302 } else {
303 if (e->quota >= skb->len) {
304 if (!(q->flags & XT_QUOTA_NO_CHANGE))
305 e->quota -= (q->flags & XT_QUOTA_PACKET) ? 1 : skb->len;
306 ret = !ret;
307 } else {
308 /* We are transitioning, log that fact. */
309 if (e->quota) {
310 quota2_log(par->hooknum,
311 skb,
312 par->in,
313 par->out,
314 q->name);
315 }
316 /* we do not allow even small packets from now on */
317 e->quota = 0;
318 }
319 }
320 spin_unlock_bh(&e->lock);
321 return ret;
322 }
324 static struct xt_match quota_mt2_reg[] __read_mostly = {
325 {
326 .name = "quota2",
327 .revision = 3,
328 .family = NFPROTO_IPV4,
329 .checkentry = quota_mt2_check,
330 .match = quota_mt2,
331 .destroy = quota_mt2_destroy,
332 .matchsize = sizeof(struct xt_quota_mtinfo2),
333 .me = THIS_MODULE,
334 },
335 {
336 .name = "quota2",
337 .revision = 3,
338 .family = NFPROTO_IPV6,
339 .checkentry = quota_mt2_check,
340 .match = quota_mt2,
341 .destroy = quota_mt2_destroy,
342 .matchsize = sizeof(struct xt_quota_mtinfo2),
343 .me = THIS_MODULE,
344 },
345 };
347 static int __init quota_mt2_init(void)
348 {
349 int ret;
350 pr_debug("xt_quota2: init()");
352 #ifdef CONFIG_NETFILTER_XT_MATCH_QUOTA2_LOG
353 nflognl = netlink_kernel_create(&init_net, NETLINK_NFLOG, NULL);
354 if (!nflognl)
355 return -ENOMEM;
356 #endif
358 proc_xt_quota = proc_mkdir("xt_quota", init_net.proc_net);
359 if (proc_xt_quota == NULL)
360 return -EACCES;
362 ret = xt_register_matches(quota_mt2_reg, ARRAY_SIZE(quota_mt2_reg));
363 if (ret < 0)
364 remove_proc_entry("xt_quota", init_net.proc_net);
365 pr_debug("xt_quota2: init() %d", ret);
366 return ret;
367 }
369 static void __exit quota_mt2_exit(void)
370 {
371 xt_unregister_matches(quota_mt2_reg, ARRAY_SIZE(quota_mt2_reg));
372 remove_proc_entry("xt_quota", init_net.proc_net);
373 }
375 module_init(quota_mt2_init);
376 module_exit(quota_mt2_exit);
377 MODULE_DESCRIPTION("Xtables: countdown quota match; up counter");
378 MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
379 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
380 MODULE_LICENSE("GPL");
381 MODULE_ALIAS("ipt_quota2");
382 MODULE_ALIAS("ip6t_quota2");