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1da177e4 LT |
1 | /* |
2 | * netfilter module for userspace bridged Ethernet frames logging daemons | |
3 | * | |
4 | * Authors: | |
5 | * Bart De Schuymer <bdschuym@pandora.be> | |
6 | * | |
7 | * November, 2004 | |
8 | * | |
9 | * Based on ipt_ULOG.c, which is | |
10 | * (C) 2000-2002 by Harald Welte <laforge@netfilter.org> | |
11 | * | |
12 | * This module accepts two parameters: | |
13 | * | |
14 | * nlbufsiz: | |
15 | * The parameter specifies how big the buffer for each netlink multicast | |
16 | * group is. e.g. If you say nlbufsiz=8192, up to eight kb of packets will | |
17 | * get accumulated in the kernel until they are sent to userspace. It is | |
18 | * NOT possible to allocate more than 128kB, and it is strongly discouraged, | |
19 | * because atomically allocating 128kB inside the network rx softirq is not | |
20 | * reliable. Please also keep in mind that this buffer size is allocated for | |
21 | * each nlgroup you are using, so the total kernel memory usage increases | |
22 | * by that factor. | |
23 | * | |
24 | * flushtimeout: | |
25 | * Specify, after how many hundredths of a second the queue should be | |
26 | * flushed even if it is not full yet. | |
27 | * | |
28 | */ | |
29 | ||
30 | #include <linux/module.h> | |
31 | #include <linux/config.h> | |
32 | #include <linux/spinlock.h> | |
33 | #include <linux/socket.h> | |
34 | #include <linux/skbuff.h> | |
35 | #include <linux/kernel.h> | |
36 | #include <linux/timer.h> | |
37 | #include <linux/netlink.h> | |
38 | #include <linux/netdevice.h> | |
39 | #include <linux/module.h> | |
40 | #include <linux/netfilter_bridge/ebtables.h> | |
41 | #include <linux/netfilter_bridge/ebt_ulog.h> | |
42 | #include <net/sock.h> | |
43 | #include "../br_private.h" | |
44 | ||
45 | #define PRINTR(format, args...) do { if (net_ratelimit()) \ | |
46 | printk(format , ## args); } while (0) | |
47 | ||
48 | static unsigned int nlbufsiz = 4096; | |
49 | module_param(nlbufsiz, uint, 0600); | |
50 | MODULE_PARM_DESC(nlbufsiz, "netlink buffer size (number of bytes) " | |
51 | "(defaults to 4096)"); | |
52 | ||
53 | static unsigned int flushtimeout = 10; | |
54 | module_param(flushtimeout, uint, 0600); | |
55 | MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths ofa second) " | |
56 | "(defaults to 10)"); | |
57 | ||
58 | typedef struct { | |
59 | unsigned int qlen; /* number of nlmsgs' in the skb */ | |
60 | struct nlmsghdr *lastnlh; /* netlink header of last msg in skb */ | |
61 | struct sk_buff *skb; /* the pre-allocated skb */ | |
62 | struct timer_list timer; /* the timer function */ | |
63 | spinlock_t lock; /* the per-queue lock */ | |
64 | } ebt_ulog_buff_t; | |
65 | ||
66 | static ebt_ulog_buff_t ulog_buffers[EBT_ULOG_MAXNLGROUPS]; | |
67 | static struct sock *ebtulognl; | |
68 | ||
69 | /* send one ulog_buff_t to userspace */ | |
70 | static void ulog_send(unsigned int nlgroup) | |
71 | { | |
72 | ebt_ulog_buff_t *ub = &ulog_buffers[nlgroup]; | |
73 | ||
74 | if (timer_pending(&ub->timer)) | |
75 | del_timer(&ub->timer); | |
76 | ||
77 | /* last nlmsg needs NLMSG_DONE */ | |
78 | if (ub->qlen > 1) | |
79 | ub->lastnlh->nlmsg_type = NLMSG_DONE; | |
80 | ||
ac6d439d PM |
81 | NETLINK_CB(ub->skb).dst_group = nlgroup + 1; |
82 | netlink_broadcast(ebtulognl, ub->skb, 0, nlgroup + 1, GFP_ATOMIC); | |
1da177e4 LT |
83 | |
84 | ub->qlen = 0; | |
85 | ub->skb = NULL; | |
86 | } | |
87 | ||
88 | /* timer function to flush queue in flushtimeout time */ | |
89 | static void ulog_timer(unsigned long data) | |
90 | { | |
91 | spin_lock_bh(&ulog_buffers[data].lock); | |
92 | if (ulog_buffers[data].skb) | |
93 | ulog_send(data); | |
94 | spin_unlock_bh(&ulog_buffers[data].lock); | |
95 | } | |
96 | ||
97 | static struct sk_buff *ulog_alloc_skb(unsigned int size) | |
98 | { | |
99 | struct sk_buff *skb; | |
100 | ||
101 | skb = alloc_skb(nlbufsiz, GFP_ATOMIC); | |
102 | if (!skb) { | |
103 | PRINTR(KERN_ERR "ebt_ulog: can't alloc whole buffer " | |
104 | "of size %ub!\n", nlbufsiz); | |
105 | if (size < nlbufsiz) { | |
106 | /* try to allocate only as much as we need for | |
107 | * current packet */ | |
108 | skb = alloc_skb(size, GFP_ATOMIC); | |
109 | if (!skb) | |
110 | PRINTR(KERN_ERR "ebt_ulog: can't even allocate " | |
111 | "buffer of size %ub\n", size); | |
112 | } | |
113 | } | |
114 | ||
115 | return skb; | |
116 | } | |
117 | ||
118 | static void ebt_ulog(const struct sk_buff *skb, unsigned int hooknr, | |
119 | const struct net_device *in, const struct net_device *out, | |
120 | const void *data, unsigned int datalen) | |
121 | { | |
122 | ebt_ulog_packet_msg_t *pm; | |
123 | size_t size, copy_len; | |
124 | struct nlmsghdr *nlh; | |
125 | struct ebt_ulog_info *uloginfo = (struct ebt_ulog_info *)data; | |
126 | unsigned int group = uloginfo->nlgroup; | |
127 | ebt_ulog_buff_t *ub = &ulog_buffers[group]; | |
128 | spinlock_t *lock = &ub->lock; | |
129 | ||
130 | if ((uloginfo->cprange == 0) || | |
131 | (uloginfo->cprange > skb->len + ETH_HLEN)) | |
132 | copy_len = skb->len + ETH_HLEN; | |
133 | else | |
134 | copy_len = uloginfo->cprange; | |
135 | ||
136 | size = NLMSG_SPACE(sizeof(*pm) + copy_len); | |
137 | if (size > nlbufsiz) { | |
138 | PRINTR("ebt_ulog: Size %Zd needed, but nlbufsiz=%d\n", | |
139 | size, nlbufsiz); | |
140 | return; | |
141 | } | |
142 | ||
143 | spin_lock_bh(lock); | |
144 | ||
145 | if (!ub->skb) { | |
146 | if (!(ub->skb = ulog_alloc_skb(size))) | |
147 | goto alloc_failure; | |
148 | } else if (size > skb_tailroom(ub->skb)) { | |
149 | ulog_send(group); | |
150 | ||
151 | if (!(ub->skb = ulog_alloc_skb(size))) | |
152 | goto alloc_failure; | |
153 | } | |
154 | ||
155 | nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, 0, | |
156 | size - NLMSG_ALIGN(sizeof(*nlh))); | |
157 | ub->qlen++; | |
158 | ||
159 | pm = NLMSG_DATA(nlh); | |
160 | ||
161 | /* Fill in the ulog data */ | |
162 | pm->version = EBT_ULOG_VERSION; | |
163 | do_gettimeofday(&pm->stamp); | |
164 | if (ub->qlen == 1) | |
a61bbcf2 | 165 | skb_set_timestamp(ub->skb, &pm->stamp); |
1da177e4 LT |
166 | pm->data_len = copy_len; |
167 | pm->mark = skb->nfmark; | |
168 | pm->hook = hooknr; | |
169 | if (uloginfo->prefix != NULL) | |
170 | strcpy(pm->prefix, uloginfo->prefix); | |
171 | else | |
172 | *(pm->prefix) = '\0'; | |
173 | ||
174 | if (in) { | |
175 | strcpy(pm->physindev, in->name); | |
176 | /* If in isn't a bridge, then physindev==indev */ | |
177 | if (in->br_port) | |
178 | strcpy(pm->indev, in->br_port->br->dev->name); | |
179 | else | |
180 | strcpy(pm->indev, in->name); | |
181 | } else | |
182 | pm->indev[0] = pm->physindev[0] = '\0'; | |
183 | ||
184 | if (out) { | |
185 | /* If out exists, then out is a bridge port */ | |
186 | strcpy(pm->physoutdev, out->name); | |
187 | strcpy(pm->outdev, out->br_port->br->dev->name); | |
188 | } else | |
189 | pm->outdev[0] = pm->physoutdev[0] = '\0'; | |
190 | ||
191 | if (skb_copy_bits(skb, -ETH_HLEN, pm->data, copy_len) < 0) | |
192 | BUG(); | |
193 | ||
194 | if (ub->qlen > 1) | |
195 | ub->lastnlh->nlmsg_flags |= NLM_F_MULTI; | |
196 | ||
197 | ub->lastnlh = nlh; | |
198 | ||
199 | if (ub->qlen >= uloginfo->qthreshold) | |
200 | ulog_send(group); | |
201 | else if (!timer_pending(&ub->timer)) { | |
202 | ub->timer.expires = jiffies + flushtimeout * HZ / 100; | |
203 | add_timer(&ub->timer); | |
204 | } | |
205 | ||
206 | unlock: | |
207 | spin_unlock_bh(lock); | |
208 | ||
209 | return; | |
210 | ||
211 | nlmsg_failure: | |
212 | printk(KERN_CRIT "ebt_ulog: error during NLMSG_PUT. This should " | |
213 | "not happen, please report to author.\n"); | |
214 | goto unlock; | |
215 | alloc_failure: | |
216 | goto unlock; | |
217 | } | |
218 | ||
219 | static int ebt_ulog_check(const char *tablename, unsigned int hookmask, | |
220 | const struct ebt_entry *e, void *data, unsigned int datalen) | |
221 | { | |
222 | struct ebt_ulog_info *uloginfo = (struct ebt_ulog_info *)data; | |
223 | ||
224 | if (datalen != EBT_ALIGN(sizeof(struct ebt_ulog_info)) || | |
225 | uloginfo->nlgroup > 31) | |
226 | return -EINVAL; | |
227 | ||
228 | uloginfo->prefix[EBT_ULOG_PREFIX_LEN - 1] = '\0'; | |
229 | ||
230 | if (uloginfo->qthreshold > EBT_ULOG_MAX_QLEN) | |
231 | uloginfo->qthreshold = EBT_ULOG_MAX_QLEN; | |
232 | ||
233 | return 0; | |
234 | } | |
235 | ||
236 | static struct ebt_watcher ulog = { | |
237 | .name = EBT_ULOG_WATCHER, | |
238 | .watcher = ebt_ulog, | |
239 | .check = ebt_ulog_check, | |
240 | .me = THIS_MODULE, | |
241 | }; | |
242 | ||
243 | static int __init init(void) | |
244 | { | |
245 | int i, ret = 0; | |
246 | ||
247 | if (nlbufsiz >= 128*1024) { | |
248 | printk(KERN_NOTICE "ebt_ulog: Netlink buffer has to be <= 128kB," | |
249 | " please try a smaller nlbufsiz parameter.\n"); | |
250 | return -EINVAL; | |
251 | } | |
252 | ||
253 | /* initialize ulog_buffers */ | |
254 | for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) { | |
255 | init_timer(&ulog_buffers[i].timer); | |
256 | ulog_buffers[i].timer.function = ulog_timer; | |
257 | ulog_buffers[i].timer.data = i; | |
258 | spin_lock_init(&ulog_buffers[i].lock); | |
259 | } | |
260 | ||
06628607 PM |
261 | ebtulognl = netlink_kernel_create(NETLINK_NFLOG, EBT_ULOG_MAXNLGROUPS, |
262 | NULL, THIS_MODULE); | |
1da177e4 LT |
263 | if (!ebtulognl) |
264 | ret = -ENOMEM; | |
265 | else if ((ret = ebt_register_watcher(&ulog))) | |
266 | sock_release(ebtulognl->sk_socket); | |
267 | ||
268 | return ret; | |
269 | } | |
270 | ||
271 | static void __exit fini(void) | |
272 | { | |
273 | ebt_ulog_buff_t *ub; | |
274 | int i; | |
275 | ||
276 | ebt_unregister_watcher(&ulog); | |
277 | for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) { | |
278 | ub = &ulog_buffers[i]; | |
279 | if (timer_pending(&ub->timer)) | |
280 | del_timer(&ub->timer); | |
281 | spin_lock_bh(&ub->lock); | |
282 | if (ub->skb) { | |
283 | kfree_skb(ub->skb); | |
284 | ub->skb = NULL; | |
285 | } | |
286 | spin_unlock_bh(&ub->lock); | |
287 | } | |
288 | sock_release(ebtulognl->sk_socket); | |
289 | } | |
290 | ||
291 | module_init(init); | |
292 | module_exit(fini); | |
293 | MODULE_LICENSE("GPL"); | |
294 | MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>"); | |
295 | MODULE_DESCRIPTION("ebtables userspace logging module for bridged Ethernet" | |
296 | " frames"); |