Differences

This shows you the differences between two versions of the page.

--- ip_up_down [2018/10/04 10:52] – [Sockets and ioctl calls] rpjday
+++ ip_up_down [2018/10/04 11:09] (current) – [__dev_change_flags()] rpjday
@@ Line 407: / Line 407: @@
 <code>
+int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr, bool *need_copyout)
+{
+... snip ...
+	switch (cmd) {
+	/*
+	 *	These ioctl calls:
+	 *	- can be done by all.
+	 *	- atomic and do not require locking.
+	 *	- return a value
+	 */
+	case SIOCGIFFLAGS:
+	case SIOCGIFMETRIC:
+	case SIOCGIFMTU:
+	case SIOCGIFHWADDR:
+	case SIOCGIFSLAVE:
+	case SIOCGIFMAP:
+	case SIOCGIFINDEX:
+	case SIOCGIFTXQLEN:
+		dev_load(net, ifr->ifr_name);
+		rcu_read_lock();
+		ret = dev_ifsioc_locked(net, ifr, cmd);
+		rcu_read_unlock();
+		if (colon)
+			*colon = ':';
+		return ret;
+... snip ...
+	case SIOCSIFFLAGS:
+	case SIOCSIFMETRIC:
+	case SIOCSIFMTU:
+	case SIOCSIFHWADDR:
+	case SIOCSIFSLAVE:
+	case SIOCADDMULTI:
+	case SIOCDELMULTI:
+	case SIOCSIFHWBROADCAST:
+	case SIOCSMIIREG:
+	case SIOCBONDENSLAVE:
+	case SIOCBONDRELEASE:
+	case SIOCBONDSETHWADDR:
+	case SIOCBONDCHANGEACTIVE:
+	case SIOCBRADDIF:
+	case SIOCBRDELIF:
+	case SIOCSHWTSTAMP:
+		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
+			return -EPERM;
+		/* fall through */
+	case SIOCBONDSLAVEINFOQUERY:
+	case SIOCBONDINFOQUERY:
+		dev_load(net, ifr->ifr_name);
+		rtnl_lock();
+		ret = dev_ifsioc(net, ifr, cmd);
+		rtnl_unlock();
+		if (need_copyout)
+			*need_copyout = false;
+		return ret;
 </code>
+==== dev_ifsioc() ====
+<code>
+static int dev_ifsioc(struct net *net, struct ifreq *ifr, unsigned int cmd)
+{
+	int err;
+	struct net_device *dev = __dev_get_by_name(net, ifr->ifr_name);
+	const struct net_device_ops *ops;
+	if (!dev)
+		return -ENODEV;
+	ops = dev->netdev_ops;
+	switch (cmd) {
+	case SIOCSIFFLAGS:	/* Set interface flags */
+		return dev_change_flags(dev, ifr->ifr_flags);
+</code>
+===== net/core/dev.c =====
+==== dev_change_flags() ====
+<code>
+int dev_change_flags(struct net_device *dev, unsigned int flags)
+{
+	int ret;
+	unsigned int changes, old_flags = dev->flags, old_gflags = dev->gflags;
+	ret = __dev_change_flags(dev, flags);
+	if (ret < 0)
+		return ret;
+	changes = (old_flags ^ dev->flags) | (old_gflags ^ dev->gflags);
+	__dev_notify_flags(dev, old_flags, changes);
+	return ret;
+}
+</code>
+==== __dev_change_flags() ====
+<code>
+int __dev_change_flags(struct net_device *dev, unsigned int flags)
+{
+	unsigned int old_flags = dev->flags;
+	int ret;
+	ASSERT_RTNL();
+	/*
+	 *	Set the flags on our device.
+	 */
+	dev->flags = (flags & (IFF_DEBUG | IFF_NOTRAILERS | IFF_NOARP |
+			       IFF_DYNAMIC | IFF_MULTICAST | IFF_PORTSEL |
+			       IFF_AUTOMEDIA)) |
+		     (dev->flags & (IFF_UP | IFF_VOLATILE | IFF_PROMISC |
+				    IFF_ALLMULTI));
+... snip ...
+	ret = 0;
+	if ((old_flags ^ flags) & IFF_UP) {
+		if (old_flags & IFF_UP)
+			__dev_close(dev);
+		else
+			ret = __dev_open(dev);
+	}
+</code>