内核网卡参数设置：devinet_ioctl()

4180阅读　0评论2013-08-17　slp195
分类：LINUX

devinet_ioctl() 根据用户空间提供的ifreq参数和cmd操作对网卡进行设置或参数的获取
cmd：大体分为两种，即set和get
p.s. 有意思的是，用户空间的ifreq指针指向的参数需要拷贝到内存空间中，让后函数才能对参数进行解读和分析。
        copy_from_user(&ifr, arg, sizeof(struct ifreq)

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  1. struct ifreq {
  2.     char ifr_name[IFNAMSIZ];
  3.     union
  4.     {
  5.         struct sockaddr ifru_addr;
  6.         struct sockaddr ifru_dstaddr;
  7.         struct sockaddr ifru_broadaddr;
  8.         struct sockaddr ifru_netmask;
  9.         struct sockaddr ifru_hwaddr;
  10.         short int ifru_flags;
  11.         int ifru_ivalue;
  12.         int ifru_mtu;
  13.         struct ifmap ifru_map;
  14.         char ifru_slave[IFNAMSIZ]; /* Just fits the size */
  15.         char ifru_newname[IFNAMSIZ];
  16.         __caddr_t ifru_data;
  17.     } ifr_ifru;
  18. };

  20. int devinet_ioctl(unsigned int cmd, void *arg)
  21. {
  22.     struct ifreq ifr;
  23.     struct sockaddr_in *sin = (struct sockaddr_in *)&ifr.ifr_addr;
  24.     struct in_device *in_dev;
  25.     struct in_ifaddr **ifap = NULL;
  26.     struct in_ifaddr *ifa = NULL;
  27.     struct net_device *dev;
  28.     char *colon;
  29.     int ret = 0;

  31.     /*
  32.      *    Fetch the caller's info block into kernel space
  33.      */

  35.     if (copy_from_user(&ifr, arg, sizeof(struct ifreq)))
  36.         return -EFAULT;
  37.     ifr.ifr_name[IFNAMSIZ-1] = 0;

  39.     colon = strchr(ifr.ifr_name, ':');
  40.     if (colon)
  41.         *colon = 0;

  43. #ifdef CONFIG_KMOD
  44.     dev_load(ifr.ifr_name);
  45. #endif

  47.     switch(cmd) {        //根據cmd對參數進行檢查
  48.     case SIOCGIFADDR:    /* Get interface address */
  49.     case SIOCGIFBRDADDR:    /* Get the broadcast address */
  50.     case SIOCGIFDSTADDR:    /* Get the destination address */
  51.     case SIOCGIFNETMASK:    /* Get the netmask for the interface */
  52.         /* Note that this ioctls will not sleep,
  53.          so that we do not impose a lock.
  54.          One day we will be forced to put shlock here (I mean SMP)
  55.          */
  56.         memset(sin, 0, sizeof(*sin));
  57.         sin->sin_family = AF_INET;
  58.         break;

  60.     case SIOCSIFFLAGS:
  61.         if (!capable(CAP_NET_ADMIN))
  62.             return -EACCES;
  63.         break;
  64.     case SIOCSIFADDR:    /* Set interface address (and family) */
  65.     case SIOCSIFBRDADDR:    /* Set the broadcast address */
  66.     case SIOCSIFDSTADDR:    /* Set the destination address */
  67.     case SIOCSIFNETMASK:     /* Set the netmask for the interface */
  68.         if (!capable(CAP_NET_ADMIN))
  69.             return -EACCES;
  70.         if (sin->sin_family != AF_INET)
  71.             return -EINVAL;
  72.         break;
  73.     default:
  74.         return -EINVAL;
  75.     }
  76.     //鎖
  77.     dev_probe_lock();
  78.     rtnl_lock();
  79.     //獲取設備名對應的設備的數據結構（描述一個設備）
  80.     if ((dev = __dev_get_by_name(ifr.ifr_name)) == NULL) {
  81.         ret = -ENODEV;
  82.         goto done;
  83.     }

  85.     if (colon)
  86.         *colon = ':';

  88.     if ((in_dev=__in_dev_get(dev)) != NULL) {                //查找對應的設備名
  89.         for (ifap=&in_dev->ifa_list; (ifa=*ifap) != NULL; ifap=&ifa->ifa_next)
  90.             if (strcmp(ifr.ifr_name, ifa->ifa_label) == 0)
  91.                 break;
  92.     }

  94.     if (ifa == NULL && cmd != SIOCSIFADDR && cmd != SIOCSIFFLAGS) {
  95.         ret = -EADDRNOTAVAIL;
  96.         goto done;
  97.     }

  99.     switch(cmd) {                                            //在對應的設備上進行操作
  100.         case SIOCGIFADDR:    /* Get interface address */        //獲取IP
  101.             sin->sin_addr.s_addr = ifa->ifa_local;
  102.             goto rarok;

  104.         case SIOCGIFBRDADDR:    /* Get the broadcast address */
  105.             sin->sin_addr.s_addr = ifa->ifa_broadcast;
  106.             goto rarok;

  108.         case SIOCGIFDSTADDR:    /* Get the destination address */
  109.             sin->sin_addr.s_addr = ifa->ifa_address;
  110.             goto rarok;

  112.         case SIOCGIFNETMASK:    /* Get the netmask for the interface */
  113.             sin->sin_addr.s_addr = ifa->ifa_mask;
  114.             goto rarok;

  116.         case SIOCSIFFLAGS:
  117.             if (colon) {
  118.                 if (ifa == NULL) {
  119.                     ret = -EADDRNOTAVAIL;
  120.                     break;
  121.                 }
  122.                 if (!(ifr.ifr_flags&IFF_UP))
  123.                     inet_del_ifa(in_dev, ifap, 1);
  124.                 break;
  125.             }
  126.             ret = dev_change_flags(dev, ifr.ifr_flags);
  127.             break;
  128.     
  129.         case SIOCSIFADDR:    /* Set interface address (and family) */
  130.             if (inet_abc_len(sin->sin_addr.s_addr) < 0) {
  131.                 ret = -EINVAL;
  132.                 break;
  133.             }

  135.             if (!ifa) {
  136.                 if ((ifa = inet_alloc_ifa()) == NULL) {
  137.                     ret = -ENOBUFS;
  138.                     break;
  139.                 }
  140.                 if (colon)
  141.                     memcpy(ifa->ifa_label, ifr.ifr_name, IFNAMSIZ);
  142.                 else
  143.                     memcpy(ifa->ifa_label, dev->name, IFNAMSIZ);
  144.             } else {
  145.                 ret = 0;
  146.                 if (ifa->ifa_local == sin->sin_addr.s_addr)
  147.                     break;
  148.                 inet_del_ifa(in_dev, ifap, 0);
  149.                 ifa->ifa_broadcast = 0;
  150.                 ifa->ifa_anycast = 0;
  151.             }

  153.             ifa->ifa_address =
  154.             ifa->ifa_local = sin->sin_addr.s_addr;            //設置IP

  156.             if (!(dev->flags&IFF_POINTOPOINT)) {
  157.                 ifa->ifa_prefixlen = inet_abc_len(ifa->ifa_address);
  158.                 ifa->ifa_mask = inet_make_mask(ifa->ifa_prefixlen);
  159.                 if ((dev->flags&IFF_BROADCAST) && ifa->ifa_prefixlen < 31)
  160.                     ifa->ifa_broadcast = ifa->ifa_address|~ifa->ifa_mask;
  161.             } else {
  162.                 ifa->ifa_prefixlen = 32;
  163.                 ifa->ifa_mask = inet_make_mask(32);
  164.             }
  165.             ret = inet_set_ifa(dev, ifa);
  166.             break;

  168.         case SIOCSIFBRDADDR:    /* Set the broadcast address */
  169.             if (ifa->ifa_broadcast != sin->sin_addr.s_addr) {
  170.                 inet_del_ifa(in_dev, ifap, 0);
  171.                 ifa->ifa_broadcast = sin->sin_addr.s_addr;
  172.                 inet_insert_ifa(ifa);
  173.             }
  174.             break;
  175.     
  176.         case SIOCSIFDSTADDR:    /* Set the destination address */
  177.             if (ifa->ifa_address != sin->sin_addr.s_addr) {
  178.                 if (inet_abc_len(sin->sin_addr.s_addr) < 0) {
  179.                     ret = -EINVAL;
  180.                     break;
  181.                 }
  182.                 inet_del_ifa(in_dev, ifap, 0);
  183.                 ifa->ifa_address = sin->sin_addr.s_addr;
  184.                 inet_insert_ifa(ifa);
  185.             }
  186.             break;

  188.         case SIOCSIFNETMASK:     /* Set the netmask for the interface */

  190.             /*
  191.              *    The mask we set must be legal.
  192.              */
  193.             if (bad_mask(sin->sin_addr.s_addr, 0)) {
  194.                 ret = -EINVAL;
  195.                 break;
  196.             }

  198.             if (ifa->ifa_mask != sin->sin_addr.s_addr) {
  199.                 inet_del_ifa(in_dev, ifap, 0);
  200.                 ifa->ifa_mask = sin->sin_addr.s_addr;
  201.                 ifa->ifa_prefixlen = inet_mask_len(ifa->ifa_mask);
  202.                 inet_insert_ifa(ifa);
  203.             }
  204.             break;
  205.     }
  206. done:
  207.     rtnl_unlock();
  208.     dev_probe_unlock();
  209.     return ret;

  211. rarok:
  212.     rtnl_unlock();
  213.     dev_probe_unlock();
  214.     if (copy_to_user(arg, &ifr, sizeof(struct ifreq)))
  215.         return -EFAULT;
  216.     return 0;
  217. }



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