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*/
1 /*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * PACKET - implements raw packet sockets.
7 *
8 * Version: @(#)packet.c 1.0.6 05/25/93
9 *
10 * Authors: Ross Biro, <bir7@leland.Stanford.Edu>
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 * Alan Cox, <gw4pts@gw4pts.ampr.org>
13 *
14 * Fixes:
15 * Alan Cox : verify_area() now used correctly
16 * Alan Cox : new skbuff lists, look ma no backlogs!
17 * Alan Cox : tidied skbuff lists.
18 * Alan Cox : Now uses generic datagram routines I
19 * added. Also fixed the peek/read crash
20 * from all old Linux datagram code.
21 * Alan Cox : Uses the improved datagram code.
22 * Alan Cox : Added NULL's for socket options.
23 * Alan Cox : Re-commented the code.
24 * Alan Cox : Use new kernel side addressing
25 * Rob Janssen : Correct MTU usage.
26 * Dave Platt : Counter leaks caused by incorrect
27 * interrupt locking and some slightly
28 * dubious gcc output. Can you read
29 * compiler: it said _VOLATILE_
30 * Richard Kooijman : Timestamp fixes.
31 * Alan Cox : New buffers. Use sk->mac.raw.
32 * Alan Cox : sendmsg/recvmsg support.
33 *
34 * This program is free software; you can redistribute it and/or
35 * modify it under the terms of the GNU General Public License
36 * as published by the Free Software Foundation; either version
37 * 2 of the License, or (at your option) any later version.
38 *
39 */
40
41 #include <linux/types.h>
42 #include <linux/sched.h>
43 #include <linux/mm.h>
44 #include <linux/fcntl.h>
45 #include <linux/socket.h>
46 #include <linux/in.h>
47 #include <linux/inet.h>
48 #include <linux/netdevice.h>
49 #include <net/ip.h>
50 #include <net/protocol.h>
51 #include <linux/skbuff.h>
52 #include <net/sock.h>
53 #include <linux/errno.h>
54 #include <linux/timer.h>
55 #include <asm/system.h>
56 #include <asm/segment.h>
57
58 /*
59 * We really ought to have a single public _inline_ min function!
60 */
61
62 static unsigned long min(unsigned long a, unsigned long b)
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*/
63 {
64 if (a < b)
65 return(a);
66 return(b);
67 }
68
69
70 /*
71 * This should be the easiest of all, all we do is copy it into a buffer.
72 */
73
74 int packet_rcv(struct sk_buff *skb, struct device *dev, struct packet_type *pt)
/* ![[previous]](../icons/left.png)
*/
75 {
76 struct sock *sk;
77
78 /*
79 * When we registered the protocol we saved the socket in the data
80 * field for just this event.
81 */
82
83 sk = (struct sock *) pt->data;
84
85 /*
86 * Yank back the headers [hope the device set this
87 * right or kerboom...]
88 */
89
90 skb_push(skb,skb->data-skb->mac.raw);
91
92 /*
93 * The SOCK_PACKET socket receives _all_ frames.
94 */
95
96 skb->dev = dev;
97
98 /*
99 * Charge the memory to the socket. This is done specifically
100 * to prevent sockets using all the memory up.
101 */
102
103 if(sock_queue_rcv_skb(sk,skb)<0)
104 {
105 skb->sk = NULL;
106 kfree_skb(skb, FREE_READ);
107 release_sock(sk);
108 return 0;
109 }
110 /*
111 * Processing complete.
112 */
113
114 return(0);
115 }
116
117
118 /*
119 * Output a raw packet to a device layer. This bypasses all the other
120 * protocol layers and you must therefore supply it with a complete frame
121 */
122
123 static int packet_sendmsg(struct sock *sk, struct msghdr *msg, int len,
/* */
124 int noblock, int flags)
125 {
126 struct sk_buff *skb;
127 struct device *dev;
128 struct sockaddr *saddr=(struct sockaddr *)msg->msg_name;
129
130 /*
131 * Check the flags.
132 */
133
134 if (flags)
135 return(-EINVAL);
136
137 /*
138 * Get and verify the address.
139 */
140
141 if (saddr)
142 {
143 if (msg->msg_namelen < sizeof(*saddr))
144 return(-EINVAL);
145 }
146 else
147 return(-ENOTCONN); /* SOCK_PACKET must be sent giving an address */
148
149 /*
150 * Find the device first to size check it
151 */
152
153 saddr->sa_data[13] = 0;
154 dev = dev_get(saddr->sa_data);
155 if (dev == NULL)
156 {
157 return(-ENODEV);
158 }
159
160 /*
161 * You may not queue a frame bigger than the mtu. This is the lowest level
162 * raw protocol and you must do your own fragmentation at this level.
163 */
164
165 if(len>dev->mtu+dev->hard_header_len)
166 return -EMSGSIZE;
167
168 skb = sock_wmalloc(sk, len, 0, GFP_KERNEL);
169
170 /*
171 * If the write buffer is full, then tough. At this level the user gets to
172 * deal with the problem - do your own algorithmic backoffs. Thats far
173 * more flexible.
174 */
175
176 if (skb == NULL)
177 {
178 return(-ENOBUFS);
179 }
180
181 /*
182 * Fill it in
183 */
184
185 skb->sk = sk;
186 skb->free = 1;
187 memcpy_fromiovec(skb_put(skb,len), msg->msg_iov, len);
188 skb->arp = 1; /* No ARP needs doing on this (complete) frame */
189
190 /*
191 * Now send it
192 */
193
194 if (dev->flags & IFF_UP)
195 dev_queue_xmit(skb, dev, sk->priority);
196 else
197 kfree_skb(skb, FREE_WRITE);
198 return(len);
199 }
200
201 static int packet_sendto(struct sock *sk, const unsigned char *from, int len,
/* */
202 int noblock, unsigned flags, struct sockaddr_in *usin,
203 int addr_len)
204 {
205 struct iovec iov;
206 struct msghdr msg;
207
208 iov.iov_base = (void *)from;
209 iov.iov_len = len;
210
211 msg.msg_name = (void *)usin;
212 msg.msg_namelen = addr_len;
213 msg.msg_accrights = NULL;
214 msg.msg_iov = &iov;
215 msg.msg_iovlen = 1;
216
217 return packet_sendmsg(sk, &msg, len, noblock, flags);
218 }
219
220
221 /*
222 * A write to a SOCK_PACKET can't actually do anything useful and will
223 * always fail but we include it for completeness and future expansion.
224 */
225
226 static int packet_write(struct sock *sk, const unsigned char *buff,
/* */
227 int len, int noblock, unsigned flags)
228 {
229 return(packet_sendto(sk, buff, len, noblock, flags, NULL, 0));
230 }
231
232 /*
233 * Close a SOCK_PACKET socket. This is fairly simple. We immediately go
234 * to 'closed' state and remove our protocol entry in the device list.
235 * The release_sock() will destroy the socket if a user has closed the
236 * file side of the object.
237 */
238
239 static void packet_close(struct sock *sk, int timeout)
/* */
240 {
241 sk->inuse = 1;
242 sk->state = TCP_CLOSE;
243 dev_remove_pack((struct packet_type *)sk->pair);
244 kfree_s((void *)sk->pair, sizeof(struct packet_type));
245 sk->pair = NULL;
246 release_sock(sk);
247 }
248
249 /*
250 * Create a packet of type SOCK_PACKET. We do one slightly irregular
251 * thing here that wants tidying up. We borrow the 'pair' pointer in
252 * the socket object so we can find the packet_type entry in the
253 * device list. The reverse is easy as we use the data field of the
254 * packet type to point to our socket.
255 */
256
257 static int packet_init(struct sock *sk)
/* */
258 {
259 struct packet_type *p;
260
261 p = (struct packet_type *) kmalloc(sizeof(*p), GFP_KERNEL);
262 if (p == NULL)
263 return(-ENOMEM);
264
265 p->func = packet_rcv;
266 p->type = sk->num;
267 p->data = (void *)sk;
268 p->dev = NULL;
269 dev_add_pack(p);
270
271 /*
272 * We need to remember this somewhere.
273 */
274
275 sk->pair = (struct sock *)p;
276
277 return(0);
278 }
279
280
281 /*
282 * Pull a packet from our receive queue and hand it to the user.
283 * If necessary we block.
284 */
285
286 int packet_recvmsg(struct sock *sk, struct msghdr *msg, int len,
/* */
287 int noblock, int flags,int *addr_len)
288 {
289 int copied=0;
290 struct sk_buff *skb;
291 struct sockaddr *saddr=(struct sockaddr *)msg->msg_name;
292 int err;
293
294 if (sk->shutdown & RCV_SHUTDOWN)
295 return(0);
296
297 /*
298 * If the address length field is there to be filled in, we fill
299 * it in now.
300 */
301
302 if (addr_len)
303 *addr_len=sizeof(*saddr);
304
305 /*
306 * Call the generic datagram receiver. This handles all sorts
307 * of horrible races and re-entrancy so we can forget about it
308 * in the protocol layers.
309 */
310
311 skb=skb_recv_datagram(sk,flags,noblock,&err);
312
313 /*
314 * An error occurred so return it. Because skb_recv_datagram()
315 * handles the blocking we don't see and worry about blocking
316 * retries.
317 */
318
319 if(skb==NULL)
320 return err;
321
322 /*
323 * You lose any data beyond the buffer you gave. If it worries a
324 * user program they can ask the device for its MTU anyway.
325 */
326
327 copied = min(len, skb->len);
328
329 memcpy_toiovec(msg->msg_iov, skb->data, copied); /* We can't use skb_copy_datagram here */
330 sk->stamp=skb->stamp;
331
332 /*
333 * Copy the address.
334 */
335
336 if (saddr)
337 {
338 saddr->sa_family = skb->dev->type;
339 memcpy(saddr->sa_data,skb->dev->name, 14);
340 }
341
342 /*
343 * Free or return the buffer as appropriate. Again this hides all the
344 * races and re-entrancy issues from us.
345 */
346
347 skb_free_datagram(skb);
348
349 /*
350 * We are done.
351 */
352
353 release_sock(sk);
354 return(copied);
355 }
356
357 static int packet_recvfrom(struct sock *sk, unsigned char *ubuf, int size, int noblock, unsigned flags,
/* */
358 struct sockaddr_in *sa, int *addr_len)
359 {
360 struct iovec iov;
361 struct msghdr msg;
362
363 iov.iov_base = ubuf;
364 iov.iov_len = size;
365
366 msg.msg_name = (void *)sa;
367 msg.msg_namelen = 0;
368 if (addr_len)
369 msg.msg_namelen = *addr_len;
370 msg.msg_accrights = NULL;
371 msg.msg_iov = &iov;
372 msg.msg_iovlen = 1;
373
374 return packet_recvmsg(sk, &msg, size, noblock, flags, addr_len);
375 }
376
377
378
379 /*
380 * A packet read can succeed and is just the same as a recvfrom but without the
381 * addresses being recorded.
382 */
383
384 int packet_read(struct sock *sk, unsigned char *buff,
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*/
385 int len, int noblock, unsigned flags)
386 {
387 return(packet_recvfrom(sk, buff, len, noblock, flags, NULL, NULL));
388 }
389
390
391 /*
392 * This structure declares to the lower layer socket subsystem currently
393 * incorrectly embedded in the IP code how to behave. This interface needs
394 * a lot of work and will change.
395 */
396
397 struct proto packet_prot =
398 {
399 packet_close,
400 packet_read,
401 packet_write,
402 packet_sendto,
403 packet_recvfrom,
404 ip_build_header, /* Not actually used */
405 NULL,
406 NULL,
407 ip_queue_xmit, /* These two are not actually used */
408 NULL,
409 NULL,
410 NULL,
411 NULL,
412 datagram_select,
413 NULL, /* No ioctl */
414 packet_init,
415 NULL,
416 NULL, /* No set/get socket options */
417 NULL,
418 packet_sendmsg, /* Sendmsg */
419 packet_recvmsg, /* Recvmsg */
420 128,
421 0,
422 "PACKET",
423 0, 0
424 };
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*/