root/net/ipv4/packet.c

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DEFINITIONS

This source file includes following definitions.
  1. min
  2. packet_rcv
  3. packet_sendto
  4. packet_write
  5. packet_close
  6. packet_init
  7. packet_recvfrom
  8. packet_read

   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  *
  32  *              This program is free software; you can redistribute it and/or
  33  *              modify it under the terms of the GNU General Public License
  34  *              as published by the Free Software Foundation; either version
  35  *              2 of the License, or (at your option) any later version.
  36  *
  37  */
  38  
  39 #include <linux/types.h>
  40 #include <linux/sched.h>
  41 #include <linux/mm.h>
  42 #include <linux/fcntl.h>
  43 #include <linux/socket.h>
  44 #include <linux/in.h>
  45 #include <linux/inet.h>
  46 #include <linux/netdevice.h>
  47 #include <net/ip.h>
  48 #include <net/protocol.h>
  49 #include <linux/skbuff.h>
  50 #include <net/sock.h>
  51 #include <linux/errno.h>
  52 #include <linux/timer.h>
  53 #include <asm/system.h>
  54 #include <asm/segment.h>
  55 
  56 /*
  57  *      We really ought to have a single public _inline_ min function!
  58  */
  59 
  60 static unsigned long min(unsigned long a, unsigned long b)
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  61 {
  62         if (a < b) 
  63                 return(a);
  64         return(b);
  65 }
  66 
  67 
  68 /*
  69  *      This should be the easiest of all, all we do is copy it into a buffer. 
  70  */
  71  
  72 int packet_rcv(struct sk_buff *skb, struct device *dev,  struct packet_type *pt)
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  73 {
  74         struct sock *sk;
  75         unsigned long flags;
  76         
  77         /*
  78          *      When we registered the protocol we saved the socket in the data
  79          *      field for just this event.
  80          */
  81 
  82         sk = (struct sock *) pt->data;  
  83 
  84         /*
  85          *      The SOCK_PACKET socket receives _all_ frames, and as such 
  86          *      therefore needs to put the header back onto the buffer.
  87          *      (it was removed by inet_bh()).
  88          */
  89          
  90         skb->dev = dev;
  91         skb->len += dev->hard_header_len;
  92 
  93         /*
  94          *      Charge the memory to the socket. This is done specifically
  95          *      to prevent sockets using all the memory up.
  96          */
  97          
  98         if (sk->rmem_alloc & 0xFF000000) {
  99                 printk("packet_rcv: sk->rmem_alloc = %ld\n", sk->rmem_alloc);
 100                 sk->rmem_alloc = 0;
 101         }
 102 
 103         if (sk->rmem_alloc + skb->mem_len >= sk->rcvbuf) 
 104         {
 105 /*              printk("packet_rcv: drop, %d+%d>%d\n", sk->rmem_alloc, skb->mem_len, sk->rcvbuf); */
 106                 skb->sk = NULL;
 107                 kfree_skb(skb, FREE_READ);
 108                 return(0);
 109         }
 110 
 111         save_flags(flags);
 112         cli();
 113 
 114         skb->sk = sk;
 115         sk->rmem_alloc += skb->mem_len; 
 116 
 117         /*
 118          *      Queue the packet up, and wake anyone waiting for it.
 119          */
 120 
 121         skb_queue_tail(&sk->receive_queue,skb);
 122         if(!sk->dead)
 123                 sk->data_ready(sk,skb->len);
 124                 
 125         restore_flags(flags);
 126 
 127         /*
 128          *      Processing complete.
 129          */
 130          
 131         return(0);
 132 }
 133 
 134 
 135 /*
 136  *      Output a raw packet to a device layer. This bypasses all the other
 137  *      protocol layers and you must therefore supply it with a complete frame
 138  */
 139  
 140 static int packet_sendto(struct sock *sk, unsigned char *from, int len,
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 141               int noblock, unsigned flags, struct sockaddr_in *usin,
 142               int addr_len)
 143 {
 144         struct sk_buff *skb;
 145         struct device *dev;
 146         struct sockaddr *saddr=(struct sockaddr *)usin;
 147 
 148         /*
 149          *      Check the flags. 
 150          */
 151 
 152         if (flags) 
 153                 return(-EINVAL);
 154 
 155         /*
 156          *      Get and verify the address. 
 157          */
 158          
 159         if (usin) 
 160         {
 161                 if (addr_len < sizeof(*saddr)) 
 162                         return(-EINVAL);
 163         } 
 164         else
 165                 return(-EINVAL);        /* SOCK_PACKET must be sent giving an address */
 166         
 167         /*
 168          *      Find the device first to size check it 
 169          */
 170 
 171         saddr->sa_data[13] = 0;
 172         dev = dev_get(saddr->sa_data);
 173         if (dev == NULL) 
 174         {
 175                 return(-ENXIO);
 176         }
 177         
 178         /*
 179          *      You may not queue a frame bigger than the mtu. This is the lowest level
 180          *      raw protocol and you must do your own fragmentation at this level.
 181          */
 182          
 183         if(len>dev->mtu+dev->hard_header_len)
 184                 return -EMSGSIZE;
 185 
 186         skb = sk->prot->wmalloc(sk, len, 0, GFP_KERNEL);
 187 
 188         /*
 189          *      If the write buffer is full, then tough. At this level the user gets to
 190          *      deal with the problem - do your own algorithmic backoffs.
 191          */
 192          
 193         if (skb == NULL) 
 194         {
 195                 return(-ENOBUFS);
 196         }
 197         
 198         /*
 199          *      Fill it in 
 200          */
 201          
 202         skb->sk = sk;
 203         skb->free = 1;
 204         memcpy_fromfs(skb->data, from, len);
 205         skb->len = len;
 206         skb->arp = 1;           /* No ARP needs doing on this (complete) frame */
 207 
 208         /*
 209          *      Now send it
 210          */
 211 
 212         if (dev->flags & IFF_UP) 
 213                 dev_queue_xmit(skb, dev, sk->priority);
 214         else
 215                 kfree_skb(skb, FREE_WRITE);
 216         return(len);
 217 }
 218 
 219 /*
 220  *      A write to a SOCK_PACKET can't actually do anything useful and will
 221  *      always fail but we include it for completeness and future expansion.
 222  */
 223 
 224 static int packet_write(struct sock *sk, unsigned char *buff, 
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 225              int len, int noblock,  unsigned flags)
 226 {
 227         return(packet_sendto(sk, buff, len, noblock, flags, NULL, 0));
 228 }
 229 
 230 /*
 231  *      Close a SOCK_PACKET socket. This is fairly simple. We immediately go
 232  *      to 'closed' state and remove our protocol entry in the device list.
 233  *      The release_sock() will destroy the socket if a user has closed the
 234  *      file side of the object.
 235  */
 236 
 237 static void packet_close(struct sock *sk, int timeout)
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 238 {
 239         sk->inuse = 1;
 240         sk->state = TCP_CLOSE;
 241         dev_remove_pack((struct packet_type *)sk->pair);
 242         kfree_s((void *)sk->pair, sizeof(struct packet_type));
 243         sk->pair = NULL;
 244         release_sock(sk);
 245 }
 246 
 247 /*
 248  *      Create a packet of type SOCK_PACKET. We do one slightly irregular
 249  *      thing here that wants tidying up. We borrow the 'pair' pointer in
 250  *      the socket object so we can find the packet_type entry in the
 251  *      device list. The reverse is easy as we use the data field of the
 252  *      packet type to point to our socket.
 253  */
 254 
 255 static int packet_init(struct sock *sk)
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 256 {
 257         struct packet_type *p;
 258 
 259         p = (struct packet_type *) kmalloc(sizeof(*p), GFP_KERNEL);
 260         if (p == NULL) 
 261                 return(-ENOMEM);
 262 
 263         p->func = packet_rcv;
 264         p->type = sk->num;
 265         p->data = (void *)sk;
 266         p->dev = NULL;
 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 necessary we block.
 282  */
 283  
 284 int packet_recvfrom(struct sock *sk, unsigned char *to, int len,
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 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         int truesize;
 293 
 294         saddr = (struct sockaddr *)sin;
 295 
 296         if (sk->shutdown & RCV_SHUTDOWN) 
 297                 return(0);
 298                 
 299         /*
 300          *      If the address length field is there to be filled in, we fill
 301          *      it in now.
 302          */
 303 
 304         if (addr_len) 
 305                 *addr_len=sizeof(*saddr);
 306         
 307         /*
 308          *      Call the generic datagram receiver. This handles all sorts
 309          *      of horrible races and re-entrancy so we can forget about it
 310          *      in the protocol layers.
 311          */
 312          
 313         skb=skb_recv_datagram(sk,flags,noblock,&err);
 314         
 315         /*
 316          *      An error occurred so return it. Because skb_recv_datagram() 
 317          *      handles the blocking we don't see and worry about blocking
 318          *      retries.
 319          */
 320          
 321         if(skb==NULL)
 322                 return err;
 323                 
 324         /*
 325          *      You lose any data beyond the buffer you gave. If it worries a
 326          *      user program they can ask the device for its MTU anyway.
 327          */
 328          
 329         truesize = skb->len;
 330         copied = min(len, truesize);
 331 
 332         memcpy_tofs(to, skb->data, copied);     /* We can't use skb_copy_datagram here */
 333         sk->stamp=skb->stamp;
 334 
 335         /*
 336          *      Copy the address. 
 337          */
 338          
 339         if (saddr) 
 340         {
 341                 saddr->sa_family = skb->dev->type;
 342                 memcpy(saddr->sa_data,skb->dev->name, 14);
 343         }
 344         
 345         /*
 346          *      Free or return the buffer as appropriate. Again this hides all the
 347          *      races and re-entrancy issues from us.
 348          */
 349 
 350         skb_free_datagram(skb);
 351 
 352         /*
 353          *      We are done.
 354          */
 355          
 356         release_sock(sk);
 357         return(truesize);
 358 }
 359 
 360 
 361 /*
 362  *      A packet read can succeed and is just the same as a recvfrom but without the
 363  *      addresses being recorded.
 364  */
 365 
 366 int packet_read(struct sock *sk, unsigned char *buff,
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 367             int len, int noblock, unsigned flags)
 368 {
 369         return(packet_recvfrom(sk, buff, len, noblock, flags, NULL, NULL));
 370 }
 371 
 372 
 373 /*
 374  *      This structure declares to the lower layer socket subsystem currently
 375  *      incorrectly embedded in the IP code how to behave. This interface needs
 376  *      a lot of work and will change.
 377  */
 378  
 379 struct proto packet_prot = 
 380 {
 381         sock_wmalloc,
 382         sock_rmalloc,
 383         sock_wfree,
 384         sock_rfree,
 385         sock_rspace,
 386         sock_wspace,
 387         packet_close,
 388         packet_read,
 389         packet_write,
 390         packet_sendto,
 391         packet_recvfrom,
 392         ip_build_header,        /* Not actually used */
 393         NULL,
 394         NULL,
 395         ip_queue_xmit,          /* These two are not actually used */
 396         NULL,
 397         NULL,
 398         NULL,
 399         NULL, 
 400         datagram_select,
 401         NULL,
 402         packet_init,
 403         NULL,
 404         NULL,                   /* No set/get socket options */
 405         NULL,
 406         128,
 407         0,
 408         "PACKET",
 409         0, 0
 410 };

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