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authorChris Friesen <cfriesen@nortel.com>2009-05-19 15:31:50 -0700
committerDavid S. Miller <davem@davemloft.net>2009-05-19 15:36:17 -0700
commit9643f4551255ce8b3ef7470aaaf7f435a20f9182 (patch)
tree4c2fe5194a697c2e9c0e61d7a74850760315ba76 /net/ipv4/ipconfig.c
parentnet: use NLMSG_DEFAULT_SIZE in nlmsg_new() allocations (diff)
downloadlinux-dev-9643f4551255ce8b3ef7470aaaf7f435a20f9182.tar.xz
linux-dev-9643f4551255ce8b3ef7470aaaf7f435a20f9182.zip
ipv4: teach ipconfig about the MTU option in DHCP
The DHCP spec allows the server to specify the MTU. This can be useful for netbooting with UDP-based NFS-root on a network using jumbo frames. This patch allows the kernel IP autoconfiguration to handle this option correctly. It would be possible to use initramfs and add a script to set the MTU, but that seems like a complicated solution if no initramfs is otherwise necessary, and would bloat the kernel image more than this code would. This patch was originally submitted to LKML in 2003 by Hans-Peter Jansen. Signed-off-by: Chris Friesen <cfriesen@nortel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ipconfig.c')
-rw-r--r--net/ipv4/ipconfig.c41
1 files changed, 37 insertions, 4 deletions
diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index 88bf051d0cbb..f8d04c256454 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -160,6 +160,9 @@ static char user_dev_name[IFNAMSIZ] __initdata = { 0, };
/* Protocols supported by available interfaces */
static int ic_proto_have_if __initdata = 0;
+/* MTU for boot device */
+static int ic_dev_mtu __initdata = 0;
+
#ifdef IPCONFIG_DYNAMIC
static DEFINE_SPINLOCK(ic_recv_lock);
static volatile int ic_got_reply __initdata = 0; /* Proto(s) that replied */
@@ -286,7 +289,7 @@ set_sockaddr(struct sockaddr_in *sin, __be32 addr, __be16 port)
sin->sin_port = port;
}
-static int __init ic_dev_ioctl(unsigned int cmd, struct ifreq *arg)
+static int __init ic_devinet_ioctl(unsigned int cmd, struct ifreq *arg)
{
int res;
@@ -297,6 +300,17 @@ static int __init ic_dev_ioctl(unsigned int cmd, struct ifreq *arg)
return res;
}
+static int __init ic_dev_ioctl(unsigned int cmd, struct ifreq *arg)
+{
+ int res;
+
+ mm_segment_t oldfs = get_fs();
+ set_fs(get_ds());
+ res = dev_ioctl(&init_net, cmd, (struct ifreq __user *) arg);
+ set_fs(oldfs);
+ return res;
+}
+
static int __init ic_route_ioctl(unsigned int cmd, struct rtentry *arg)
{
int res;
@@ -321,20 +335,31 @@ static int __init ic_setup_if(void)
memset(&ir, 0, sizeof(ir));
strcpy(ir.ifr_ifrn.ifrn_name, ic_dev->name);
set_sockaddr(sin, ic_myaddr, 0);
- if ((err = ic_dev_ioctl(SIOCSIFADDR, &ir)) < 0) {
+ if ((err = ic_devinet_ioctl(SIOCSIFADDR, &ir)) < 0) {
printk(KERN_ERR "IP-Config: Unable to set interface address (%d).\n", err);
return -1;
}
set_sockaddr(sin, ic_netmask, 0);
- if ((err = ic_dev_ioctl(SIOCSIFNETMASK, &ir)) < 0) {
+ if ((err = ic_devinet_ioctl(SIOCSIFNETMASK, &ir)) < 0) {
printk(KERN_ERR "IP-Config: Unable to set interface netmask (%d).\n", err);
return -1;
}
set_sockaddr(sin, ic_myaddr | ~ic_netmask, 0);
- if ((err = ic_dev_ioctl(SIOCSIFBRDADDR, &ir)) < 0) {
+ if ((err = ic_devinet_ioctl(SIOCSIFBRDADDR, &ir)) < 0) {
printk(KERN_ERR "IP-Config: Unable to set interface broadcast address (%d).\n", err);
return -1;
}
+ /* Handle the case where we need non-standard MTU on the boot link (a network
+ * using jumbo frames, for instance). If we can't set the mtu, don't error
+ * out, we'll try to muddle along.
+ */
+ if (ic_dev_mtu != 0) {
+ strcpy(ir.ifr_name, ic_dev->name);
+ ir.ifr_mtu = ic_dev_mtu;
+ if ((err = ic_dev_ioctl(SIOCSIFMTU, &ir)) < 0)
+ printk(KERN_ERR "IP-Config: Unable to set interface mtu to %d (%d).\n",
+ ic_dev_mtu, err);
+ }
return 0;
}
@@ -623,6 +648,7 @@ ic_dhcp_init_options(u8 *options)
12, /* Host name */
15, /* Domain name */
17, /* Boot path */
+ 26, /* MTU */
40, /* NIS domain name */
};
@@ -798,6 +824,7 @@ static void __init ic_do_bootp_ext(u8 *ext)
{
u8 servers;
int i;
+ u16 mtu;
#ifdef IPCONFIG_DEBUG
u8 *c;
@@ -837,6 +864,10 @@ static void __init ic_do_bootp_ext(u8 *ext)
if (!root_server_path[0])
ic_bootp_string(root_server_path, ext+1, *ext, sizeof(root_server_path));
break;
+ case 26: /* Interface MTU */
+ memcpy(&mtu, ext+1, sizeof(mtu));
+ ic_dev_mtu = ntohs(mtu);
+ break;
case 40: /* NIS Domain name (_not_ DNS) */
ic_bootp_string(utsname()->domainname, ext+1, *ext, __NEW_UTS_LEN);
break;
@@ -1403,6 +1434,8 @@ static int __init ip_auto_config(void)
printk(",\n bootserver=%pI4", &ic_servaddr);
printk(", rootserver=%pI4", &root_server_addr);
printk(", rootpath=%s", root_server_path);
+ if (ic_dev_mtu)
+ printk(", mtu=%d", ic_dev_mtu);
printk("\n");
#endif /* !SILENT */