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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 *
25 *
26 * This program is free software; you can redistribute it and/or
27 * modify it under the terms of the GNU General Public License
28 * as published by the Free Software Foundation; either version
29 * 2 of the License, or (at your option) any later version.
30 *
31 */
32
33 #include <linux/types.h>
34 #include <linux/sched.h>
35 #include <linux/fcntl.h>
36 #include <linux/socket.h>
37 #include <linux/in.h>
38 #include <linux/inet.h>
39 #include <linux/netdevice.h>
40 #include "ip.h"
41 #include "protocol.h"
42 #include <linux/skbuff.h>
43 #include "sock.h"
44 #include <linux/errno.h>
45 #include <linux/timer.h>
46 #include <asm/system.h>
47 #include <asm/segment.h>
48
49 /*
50 * We really ought to have a single public _inline_ min function!
51 */
52
53 static unsigned long min(unsigned long a, unsigned long b)
/* ![[next]](../icons/right.png)
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*/
54 {
55 if (a < b)
56 return(a);
57 return(b);
58 }
59
60
61 /*
62 * This should be the easiest of all, all we do is copy it into a buffer.
63 */
64
65 int packet_rcv(struct sk_buff *skb, struct device *dev, struct packet_type *pt)
/* ![[previous]](../icons/left.png)
*/
66 {
67 struct sock *sk;
68
69 /*
70 * When we registered the protcol we saved the socket in the data
71 * field for just this event.
72 */
73
74 sk = (struct sock *) pt->data;
75
76 /*
77 * The SOCK_PACKET socket receives _all_ frames, and as such
78 * therefore needs to put the header back onto the buffer.
79 * (it was removed by inet_bh()).
80 */
81
82 skb->dev = dev;
83 skb->len += dev->hard_header_len;
84
85 skb->sk = sk;
86
87 /*
88 * Charge the memory to the socket. This is done specificially
89 * to prevent sockets using all the memory up.
90 */
91
92 if (sk->rmem_alloc + skb->mem_len >= sk->rcvbuf)
93 {
94 skb->sk = NULL;
95 kfree_skb(skb, FREE_READ);
96 return(0);
97 }
98 sk->rmem_alloc += skb->mem_len;
99
100 /*
101 * Queue the packet up, and wake anyone waiting for it.
102 */
103
104 skb_queue_tail(&sk->receive_queue,skb);
105 wake_up_interruptible(sk->sleep);
106
107 /*
108 * Processing complete.
109 */
110
111 release_sock(sk); /* This is now effectively surplus in this layer */
112 return(0);
113 }
114
115
116 /*
117 * Output a raw packet to a device layer. This bypasses all the other
118 * protocol layers and you must therefore supply it with a complete frame
119 */
120
121 static int packet_sendto(struct sock *sk, unsigned char *from, int len,
/* */
122 int noblock, unsigned flags, struct sockaddr_in *usin,
123 int addr_len)
124 {
125 struct sk_buff *skb;
126 struct device *dev;
127 struct sockaddr saddr;
128 int err;
129
130 /*
131 * Check the flags.
132 */
133
134 if (flags)
135 return(-EINVAL);
136 if (len < 0)
137 return(-EINVAL);
138
139 /*
140 * Get and verify the address.
141 */
142
143 if (usin)
144 {
145 if (addr_len < sizeof(saddr))
146 return(-EINVAL);
147 err=verify_area(VERIFY_READ, usin, sizeof(saddr));
148 if(err)
149 return err;
150 memcpy_fromfs(&saddr, usin, sizeof(saddr));
151 }
152 else
153 return(-EINVAL); /* SOCK_PACKET must be sent giving an address */
154
155
156 /*
157 * Check the buffer is readable.
158 */
159
160 err=verify_area(VERIFY_READ,from,len);
161 if(err)
162 return(err);
163
164 /*
165 * Find the device first to size check it
166 */
167
168 saddr.sa_data[13] = 0;
169 dev = dev_get(saddr.sa_data);
170 if (dev == NULL)
171 {
172 return(-ENXIO);
173 }
174
175 /*
176 * You may not queue a frame bigger than the mtu. This is the lowest level
177 * raw protocol and you must do your own fragmentation at this level.
178 */
179
180 if(len>dev->mtu)
181 return -EMSGSIZE;
182
183 /*
184 * Now allocate the buffer, knowing 4K pagelimits wont break this line.
185 */
186
187 skb = sk->prot->wmalloc(sk, len, 0, GFP_KERNEL);
188
189 /*
190 * If the write buffer is full, then tough. At this level the user gets to
191 * deal with the problem.
192 */
193
194 if (skb == NULL)
195 {
196 return(-ENOBUFS);
197 }
198
199 /*
200 * Fill it in
201 */
202
203 skb->sk = sk;
204 skb->free = 1;
205 memcpy_fromfs(skb->data, from, len);
206 skb->len = len;
207 skb->arp = 1; /* No ARP needs doing on this (complete) frame */
208
209 /*
210 * Now send it
211 */
212
213 if (dev->flags & IFF_UP)
214 dev_queue_xmit(skb, dev, sk->priority);
215 else
216 kfree_skb(skb, FREE_WRITE);
217 return(len);
218 }
219
220 /*
221 * A write to a SOCK_PACKET can't actually do anything useful and will
222 * always fail but we include it for completeness and future expansion.
223 */
224
225 static int packet_write(struct sock *sk, unsigned char *buff,
/* */
226 int len, int noblock, unsigned flags)
227 {
228 return(packet_sendto(sk, buff, len, noblock, flags, NULL, 0));
229 }
230
231 /*
232 * Close a SOCK_PACKET socket. This is fairly simple. We immediately go
233 * to 'closed' state and remove our protocol entry in the device list.
234 * The release_sock() will destroy the socket if a user has closed the
235 * file side of the object.
236 */
237
238 static void packet_close(struct sock *sk, int timeout)
/* */
239 {
240 sk->inuse = 1;
241 sk->state = TCP_CLOSE;
242 dev_remove_pack((struct packet_type *)sk->pair);
243 kfree_s((void *)sk->pair, sizeof(struct packet_type));
244 sk->pair = NULL;
245 release_sock(sk);
246 }
247
248 /*
249 * Create a packet of type SOCK_PACKET. We do one slightly irregular
250 * thing here that wants tidying up. We borrow the 'pair' pointer in
251 * the socket object so we can find the packet_type entry in the
252 * device list. The reverse is easy as we use the data field of the
253 * packet type to point to our socket.
254 */
255
256 static int packet_init(struct sock *sk)
/* */
257 {
258 struct packet_type *p;
259
260 p = (struct packet_type *) kmalloc(sizeof(*p), GFP_KERNEL);
261 if (p == NULL)
262 return(-ENOMEM);
263
264 p->func = packet_rcv;
265 p->type = sk->num;
266 p->data = (void *)sk;
267 dev_add_pack(p);
268
269 /*
270 * We need to remember this somewhere.
271 */
272
273 sk->pair = (struct sock *)p;
274
275 return(0);
276 }
277
278
279 /*
280 * Pull a packet from our receive queue and hand it to the user.
281 * If neccessary we block.
282 */
283
284 int packet_recvfrom(struct sock *sk, unsigned char *to, int len,
/* */
285 int noblock, unsigned flags, struct sockaddr_in *sin,
286 int *addr_len)
287 {
288 int copied=0;
289 struct sk_buff *skb;
290 struct sockaddr *saddr;
291 int err;
292
293 saddr = (struct sockaddr *)sin;
294 if (len == 0)
295 return(0);
296 if (len < 0)
297 return(-EINVAL);
298
299 if (sk->shutdown & RCV_SHUTDOWN)
300 return(0);
301
302 /*
303 * If the address length field is there to be filled in, we fill
304 * it in now.
305 */
306
307 if (addr_len)
308 {
309 err=verify_area(VERIFY_WRITE, addr_len, sizeof(*addr_len));
310 if(err)
311 return err;
312 put_fs_long(sizeof(*saddr), addr_len);
313 }
314
315 if(saddr)
316 {
317 err=verify_area(VERIFY_WRITE, saddr, sizeof(*saddr));
318 if(err)
319 return err;
320 }
321
322 /*
323 * Check the user given area can be written to.
324 */
325
326 err=verify_area(VERIFY_WRITE,to,len);
327 if(err)
328 return err;
329
330 /*
331 * Call the generic datagram receiver. This handles all sorts
332 * of horrible races and re-entrancy so we can forget about it
333 * in the protocol layers.
334 */
335
336 skb=skb_recv_datagram(sk,flags,noblock,&err);
337
338 /*
339 * An error occured so return it. Because skb_recv_datagram()
340 * handles the blocking we don't see and worry about blocking
341 * retries.
342 */
343
344 if(skb==NULL)
345 return err;
346
347 /*
348 * You lose any data beyond the buffer you gave. If it worries a
349 * user program they can ask the device for its MTU anyway.
350 */
351
352 copied = min(len, skb->len);
353
354 memcpy_tofs(to, skb->data, copied); /* We can't use skb_copy_datagram here */
355
356 /*
357 * Copy the address.
358 */
359
360 if (saddr)
361 {
362 struct sockaddr addr;
363
364 addr.sa_family = skb->dev->type;
365 memcpy(addr.sa_data,skb->dev->name, 14);
366 memcpy_tofs(saddr, &addr, sizeof(*saddr));
367 }
368
369 /*
370 * Free or return the buffer as appropriate. Again this hides all the
371 * races and re-entrancy issues from us.
372 */
373
374 skb_free_datagram(skb);
375
376 /*
377 * We are done.
378 */
379
380 release_sock(sk);
381 return(copied);
382 }
383
384
385 /*
386 * A packet read can succeed and is just the same as a recvfrom but without the
387 * addresses being recorded.
388 */
389
390 int packet_read(struct sock *sk, unsigned char *buff,
/* ![[last]](../icons/n_last.png)
*/
391 int len, int noblock, unsigned flags)
392 {
393 return(packet_recvfrom(sk, buff, len, noblock, flags, NULL, NULL));
394 }
395
396
397 /*
398 * This structure declares to the lower layer socket subsystem currently
399 * incorrectly embedded in the IP code how to behave. This interface needs
400 * a lot of work and will change.
401 */
402
403 struct proto packet_prot =
404 {
405 sock_wmalloc,
406 sock_rmalloc,
407 sock_wfree,
408 sock_rfree,
409 sock_rspace,
410 sock_wspace,
411 packet_close,
412 packet_read,
413 packet_write,
414 packet_sendto,
415 packet_recvfrom,
416 ip_build_header, /* Not actually used */
417 NULL,
418 NULL,
419 ip_queue_xmit, /* These two are not actually used */
420 ip_retransmit,
421 NULL,
422 NULL,
423 NULL,
424 datagram_select,
425 NULL,
426 packet_init,
427 NULL,
428 NULL, /* No set/get socket options */
429 NULL,
430 128,
431 0,
432 {NULL,},
433 "PACKET"
434 };
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*/