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/* |
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qemu-start.c - Part of qemu-start, a package to start qemu nicely. |
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Copyright (c) 2006 Frodo Looijaard <frodo@frodo.looijaard.name> |
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|
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This program is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 2 of the License, or |
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(at your option) any later version. |
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|
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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|
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You should have received a copy of the GNU General Public License |
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along with this program; if not, write to the Free Software |
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
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*/ |
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|
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#define _GNU_SOURCE /* asprintf */ |
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#include <stdio.h> |
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#include <string.h> |
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#include <sys/types.h> |
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#include <pwd.h> |
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#include <grp.h> |
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#include <sys/stat.h> |
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#include <sys/ioctl.h> |
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#include <fcntl.h> |
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#include <unistd.h> |
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#include <stdlib.h> |
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#include <net/if.h> |
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#include <linux/if_tun.h> |
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|
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#define QEMU "/usr/bin/qemu" |
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#define USER "qemu" |
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|
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/* Tiny code to open tap/tun device, and hand the fd to qemu. |
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Run as root, drops to given user. */ |
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int main(int argc, char *argv[]) |
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{ |
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struct ifreq ifr; |
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struct passwd *userdata; |
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char *newargs[argc + 2]; |
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int i,fd,vlan,tapnr; |
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char *ptr; |
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char *command; |
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char *display; |
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char *xauthfile; |
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|
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/* Check parameters */ |
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if (argc < 4) { |
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fprintf(stderr, "Usage: qemu-start TAPDEVNR VLAN SYSTEM <qemu options>...\n"); |
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fprintf(stderr, " A device tapTAPDEVNR must have been configured.\n"); |
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fprintf(stderr, " VLAN is the Virtual LAN number (just use 0 if unsure).\n"); |
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fprintf(stderr, " SYSTEM is the system to emulate. Use \"\" for the current architecture\n"); |
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fprintf(stderr, " (uses /usr/bin/qemm); else a binary /usr/bin/qemu-system-SYSTEM is used.\n"); |
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exit(1); |
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} |
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|
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/* First parameter: TAPDEVNR */ |
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tapnr = strtol(argv[1],&ptr,0); |
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if (*ptr) { |
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fprintf(stderr, "Invalid value for TAPDEVNR parameter (use a number!)\n"); |
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exit(1); |
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} |
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|
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/* Second parameter: VLAN */ |
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vlan = strtol(argv[2],&ptr,0); |
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if (*ptr) { |
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fprintf(stderr, "Invalid value for VLAN parameter (use a number!)\n"); |
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exit(1); |
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} |
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|
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/* Open /dev/net/tun */ |
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fd = open("/dev/net/tun", O_RDWR); |
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if (fd < 0) { |
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perror("Could not open /dev/net/tun"); |
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exit(1); |
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} |
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|
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/* Bind to the right tap device */ |
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memset(&ifr, 0, sizeof(ifr)); |
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ifr.ifr_flags = IFF_TAP | IFF_NO_PI; |
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snprintf(ifr.ifr_name,IFNAMSIZ,"tap%d",tapnr); |
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|
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if (ioctl(fd, TUNSETIFF, (void *) &ifr) != 0) { |
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perror("Could not get tap device"); |
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exit(1); |
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} |
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|
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/* Fix X-display */ |
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userdata = getpwuid(getuid()); |
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if (! (xauthfile = getenv("XAUTHORITY"))) |
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asprintf(&xauthfile,"~%s/.Xauthority",userdata->pw_name); |
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setuid(0); |
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setgid(0); |
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asprintf(&command,"xauth -f %s extract - $(echo $DISPLAY|sed \"s,^localhost,$(hostname)/unix,\") | xauth -f ~%s/.Xauthority merge -; chown %s: ~%s/.Xauthority",xauthfile,USER,USER,USER); |
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fprintf(stderr,"%s\n",command); |
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system(command); |
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|
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/* Set correct userid. */ |
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userdata = getpwnam(USER); |
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if (!userdata) { |
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fprintf(stderr, "No user '%s'\n", USER); |
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exit(1); |
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} |
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setgroups(0, NULL); |
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setgid(userdata->pw_gid); |
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if (setuid(userdata->pw_uid) != 0) { |
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perror("setting uid"); |
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exit(1); |
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} |
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|
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/* Clean the environment */ |
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display=getenv("DISPLAY"); |
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clearenv(); |
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setenv("HOME",userdata->pw_dir,1); |
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setenv("DISPLAY",display,1); |
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setenv("PATH","/usr/bin:/bin:/usr/local/bin",1); |
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setenv("LOGNAME",userdata->pw_name,1); |
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setenv("USER",userdata->pw_name,1); |
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|
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/* Create the right qemu invocation */ |
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if (!strlen(argv[3])) |
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newargs[0] = QEMU; |
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else |
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asprintf(&newargs[0],"%s-system-%s",QEMU,argv[3]); |
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newargs[1] = "-net"; |
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asprintf(&newargs[2],"nic,vlan=%d",vlan); |
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newargs[3] = "-net"; |
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asprintf(&newargs[4],"tap,fd=%d,vlan=%d",fd,vlan); |
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for (i = 4; i <= argc; i++) |
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newargs[i+1] = argv[i]; |
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|
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execvp(newargs[0], newargs); |
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exit(1); |
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} |
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