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Re: [Qemu-devel] [patch] Linux TUN/TAP driver updates
From: |
Jean-Christian de Rivaz |
Subject: |
Re: [Qemu-devel] [patch] Linux TUN/TAP driver updates |
Date: |
Sat, 16 Apr 2005 00:40:38 +0200 |
User-agent: |
Mozilla Thunderbird 1.0 (X11/20050116) |
Hi,
This is a good idea. I haved posted a similar patch to this mailing list
the 13 feb 2005 but I have see no reaction at all at this time. Maybe
you can find something usefull in the attached patch to improve the
support of static TUN/TAP. The patch is outdated now, but I can update
it to the current CVS if there is any interrest. Just tell me.
Static TUN is good in the situation where you have a superuser that
manage the interfaces. It set them and assign them to each users. it can
also setup a DHCP server to distribute IP addresses. Users just lunch
quemu with there static TUN in the option and magicaly get a working
network without any need to sudo, setuid or whatever that can have any
security risk.
You can also imagine a virtual machine manager application that setup
the network interfaces and lunch the qemu instances. This is the
direction I like the most.
Have a good day,
--
Henrik Nordstrom a écrit :
The attached patch updates the Linux TUN/TAP interface
- Allow use of static/persistent TUN/TAP devices, eleminating the need
to run anything as root when starting qemu.
- A minor bugfix in filedescriptor based TUN/TAP devices to allow more
than one filedescriptor (was colliding on the qemu internal device name).
- Added the interface index as argument to the ifup script to simplify
integration.
A small howto use persistent TUN/TAP devices:
1. Grab the tunctl tool from UML.
<url:http://www.user-mode-linux.org/cvs/tools/tunctl/>
<url:http://www.fifi.org/cgi-bin/man2html/usr/share/man/man1/tunctl.1.gz>
this small tools allows you to create persistent TAP devices with a
fixed name on the host. A persistent tap device stays until it is
manually deleted with tunctl.
2. Configure the host side of the created TAP devices using your normal
network setup tools, or the network configuration tools provided by your
distribution vendor if preferred.
3. When starting qemu, specify the TAP device names with the new
-tun-dev qemu command line option.
-tun-dev name use this already created tun device
-tun-dev can be specified multiple times if you want qemu to connect to
more than one device.
Regards
Henrik
--
Jean-Christian de Rivaz
Index: qemu-doc.texi
===================================================================
RCS file: /cvsroot/qemu/qemu/qemu-doc.texi,v
retrieving revision 1.55
diff -u -r1.55 qemu-doc.texi
--- qemu-doc.texi 10 Feb 2005 21:46:47 -0000 1.55
+++ qemu-doc.texi 13 Feb 2005 01:59:04 -0000
@@ -212,6 +212,22 @@
aa:bb:cc:dd:ee:ff in hexa). The mac address is incremented for each
new network interface.
address@hidden -tun devname
+Try to use @var{devname} while opening a tap/tun host network interface and use
+it. If it work, the network init script is not executed for this
+interface. If it don't work, the interface will use the name assigned
+by the operating system and the network init script is executed.
+
+This option permit the use of preconfigured interface. For example, as
+root you can assign a tun interface to a user and configure it like this:
address@hidden
+tunctl -u bob -t tun2
+ifconfig tun2 192.168.2.1
address@hidden example
+Then bob can use this interface with the option "-tun tun2". Note that
+option permit the use of a DHCP server on the host to configure the
+guest interface.
+
@item -tun-fd fd
Assumes @var{fd} talks to a tap/tun host network interface and use
it. Read @url{http://bellard.org/qemu/tetrinet.html} to have an
Index: vl.c
===================================================================
RCS file: /cvsroot/qemu/qemu/vl.c,v
retrieving revision 1.120
diff -u -r1.120 vl.c
--- vl.c 10 Feb 2005 22:00:06 -0000 1.120
+++ vl.c 13 Feb 2005 01:59:05 -0000
@@ -1600,7 +1600,7 @@
}
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
- pstrcpy(ifr.ifr_name, IFNAMSIZ, "tun%d");
+ pstrcpy(ifr.ifr_name, IFNAMSIZ, (ifname && *ifname) ? ifname : "tun%d");
ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
if (ret != 0) {
fprintf(stderr, "warning: could not configure /dev/net/tun: no virtual
network emulation\n");
@@ -1626,7 +1626,7 @@
qemu_add_fd_read_handler(nd->fd, fd_can_read, fd_read, opaque);
}
-static int net_tun_init(NetDriverState *nd)
+static int net_tun_init(NetDriverState *nd, int script)
{
int pid, status;
char *args[3];
@@ -1637,7 +1637,7 @@
return -1;
/* try to launch network init script */
- pid = fork();
+ pid = script ? fork() : -1;
if (pid >= 0) {
if (pid == 0) {
parg = args;
@@ -2731,6 +2731,7 @@
"-nics n simulate 'n' network cards [default=1]\n"
"-macaddr addr set the mac address of the first interface\n"
"-n script set tap/tun network init script [default=%s]\n"
+ "-tun devname try to use devname while opening tap/tun
interface\n"
"-tun-fd fd use this fd as already opened tap/tun interface\n"
#ifdef CONFIG_SLIRP
"-user-net use user mode network stack [default if no tap/tun
script]\n"
@@ -2819,6 +2820,7 @@
QEMU_OPTION_nics,
QEMU_OPTION_macaddr,
QEMU_OPTION_n,
+ QEMU_OPTION_tun,
QEMU_OPTION_tun_fd,
QEMU_OPTION_user_net,
QEMU_OPTION_tftp,
@@ -2880,6 +2882,7 @@
{ "nics", HAS_ARG, QEMU_OPTION_nics},
{ "macaddr", HAS_ARG, QEMU_OPTION_macaddr},
{ "n", HAS_ARG, QEMU_OPTION_n },
+ { "tun", HAS_ARG, QEMU_OPTION_tun },
{ "tun-fd", HAS_ARG, QEMU_OPTION_tun_fd },
#ifdef CONFIG_SLIRP
{ "user-net", 0, QEMU_OPTION_user_net },
@@ -2990,7 +2993,7 @@
int cyls, heads, secs, translation;
int start_emulation = 1;
uint8_t macaddr[6];
- int net_if_type, nb_tun_fds, tun_fds[MAX_NICS];
+ int net_if_type, nb_tun, nb_tun_fds, cnt_tun_fds, tun_fds[MAX_NICS];
int optind;
const char *r, *optarg;
CharDriverState *monitor_hd;
@@ -3037,7 +3040,12 @@
parallel_devices[i][0] = '\0';
parallel_device_index = 0;
+ for(i = 0; i < MAX_NICS; i++) {
+ nd_table[i].ifname[0] = '\0';
+ }
+ nb_tun = 0;
nb_tun_fds = 0;
+ cnt_tun_fds = 0;
net_if_type = -1;
nb_nics = 1;
/* default mac address of the first network interface */
@@ -3141,18 +3149,25 @@
case QEMU_OPTION_append:
kernel_cmdline = optarg;
break;
+ case QEMU_OPTION_tun:
+ net_if_type = NET_IF_TUN;
+ if (nb_tun+nb_tun_fds < MAX_NICS) {
+ pstrcpy(nd_table[nb_tun++].ifname, IFNAMSIZ, optarg);
+ }
+ break;
case QEMU_OPTION_tun_fd:
{
const char *p;
int fd;
net_if_type = NET_IF_TUN;
- if (nb_tun_fds < MAX_NICS) {
+ if (nb_tun+nb_tun_fds < MAX_NICS) {
fd = strtol(optarg, (char **)&p, 0);
if (*p != '\0') {
fprintf(stderr, "qemu: invalid fd for network
interface %d\n", nb_tun_fds);
exit(1);
}
tun_fds[nb_tun_fds++] = fd;
+ nb_tun++;
}
}
break;
@@ -3426,12 +3441,20 @@
#endif
#if !defined(_WIN32)
case NET_IF_TUN:
- if (i < nb_tun_fds) {
- net_fd_init(nd, tun_fds[i]);
- } else {
- if (net_tun_init(nd) < 0)
- net_dummy_init(nd);
- }
+ if (nd->ifname && *(nd->ifname)) {
+ if (net_tun_init(nd, 0) < 0) {
+ nd->ifname[0] = '\0';
+ if (net_tun_init(nd, 1) < 0)
+ net_dummy_init(nd);
+ }
+ } else {
+ if (cnt_tun_fds < nb_tun_fds) {
+ net_fd_init(nd, tun_fds[cnt_tun_fds++]);
+ } else {
+ if (net_tun_init(nd, 1) < 0)
+ net_dummy_init(nd);
+ }
+ }
break;
#endif
case NET_IF_DUMMY: