2012-01-26 14:42:24 +00:00
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/*
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* QEMU Bridge Helper
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*
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* Copyright IBM, Corp. 2011
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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* Richa Marwaha <rmarwah@linux.vnet.ibm.com>
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* Corey Bryant <coreyb@linux.vnet.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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2019-06-04 11:52:21 +00:00
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*/
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/*
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* Known shortcomings:
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* - There is no manual page
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* - The syntax of the ACL file is not documented anywhere
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* - parse_acl_file() doesn't report fopen() failure properly, fails
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* to check ferror() after fgets() failure, arbitrarily truncates
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* long lines, handles whitespace inconsistently, error messages
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* don't point to the offending file and line, errors in included
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* files are reported, but otherwise ignored, ...
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2012-01-26 14:42:24 +00:00
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*/
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2016-01-29 17:50:05 +00:00
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#include "qemu/osdep.h"
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2012-01-26 14:42:24 +00:00
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#include <sys/ioctl.h>
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <sys/prctl.h>
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#include <net/if.h>
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#include <linux/sockios.h>
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2012-07-12 13:24:31 +00:00
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#ifndef SIOCBRADDIF
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#include <linux/if_bridge.h>
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#endif
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2012-12-17 17:20:00 +00:00
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#include "qemu/queue.h"
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2012-01-26 14:42:25 +00:00
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2012-01-26 14:42:24 +00:00
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#include "net/tap-linux.h"
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2012-01-26 14:42:26 +00:00
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#ifdef CONFIG_LIBCAP
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#include <cap-ng.h>
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#endif
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2012-01-26 14:42:25 +00:00
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#define DEFAULT_ACL_FILE CONFIG_QEMU_CONFDIR "/bridge.conf"
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enum {
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ACL_ALLOW = 0,
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ACL_ALLOW_ALL,
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ACL_DENY,
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ACL_DENY_ALL,
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};
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typedef struct ACLRule {
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int type;
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char iface[IFNAMSIZ];
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QSIMPLEQ_ENTRY(ACLRule) entry;
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} ACLRule;
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typedef QSIMPLEQ_HEAD(ACLList, ACLRule) ACLList;
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2012-01-26 14:42:24 +00:00
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static void usage(void)
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{
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fprintf(stderr,
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"Usage: qemu-bridge-helper [--use-vnet] --br=bridge --fd=unixfd\n");
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}
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2012-01-26 14:42:25 +00:00
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static int parse_acl_file(const char *filename, ACLList *acl_list)
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{
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FILE *f;
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char line[4096];
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ACLRule *acl_rule;
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f = fopen(filename, "r");
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if (f == NULL) {
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return -1;
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}
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while (fgets(line, sizeof(line), f) != NULL) {
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char *ptr = line;
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char *cmd, *arg, *argend;
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2019-05-14 18:03:06 +00:00
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while (g_ascii_isspace(*ptr)) {
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2012-01-26 14:42:25 +00:00
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ptr++;
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}
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/* skip comments and empty lines */
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if (*ptr == '#' || *ptr == 0) {
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continue;
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}
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cmd = ptr;
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arg = strchr(cmd, ' ');
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if (arg == NULL) {
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arg = strchr(cmd, '\t');
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}
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if (arg == NULL) {
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fprintf(stderr, "Invalid config line:\n %s\n", line);
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fclose(f);
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errno = EINVAL;
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return -1;
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}
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*arg = 0;
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arg++;
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2019-05-14 18:03:06 +00:00
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while (g_ascii_isspace(*arg)) {
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2012-01-26 14:42:25 +00:00
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arg++;
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}
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argend = arg + strlen(arg);
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2019-05-14 18:03:06 +00:00
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while (arg != argend && g_ascii_isspace(*(argend - 1))) {
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2012-01-26 14:42:25 +00:00
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argend--;
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}
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*argend = 0;
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if (strcmp(cmd, "deny") == 0) {
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acl_rule = g_malloc(sizeof(*acl_rule));
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if (strcmp(arg, "all") == 0) {
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acl_rule->type = ACL_DENY_ALL;
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} else {
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acl_rule->type = ACL_DENY;
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snprintf(acl_rule->iface, IFNAMSIZ, "%s", arg);
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}
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QSIMPLEQ_INSERT_TAIL(acl_list, acl_rule, entry);
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} else if (strcmp(cmd, "allow") == 0) {
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acl_rule = g_malloc(sizeof(*acl_rule));
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if (strcmp(arg, "all") == 0) {
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acl_rule->type = ACL_ALLOW_ALL;
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} else {
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acl_rule->type = ACL_ALLOW;
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snprintf(acl_rule->iface, IFNAMSIZ, "%s", arg);
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}
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QSIMPLEQ_INSERT_TAIL(acl_list, acl_rule, entry);
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} else if (strcmp(cmd, "include") == 0) {
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/* ignore errors */
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parse_acl_file(arg, acl_list);
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} else {
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fprintf(stderr, "Unknown command `%s'\n", cmd);
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fclose(f);
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errno = EINVAL;
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return -1;
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}
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}
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fclose(f);
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return 0;
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}
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2012-01-26 14:42:24 +00:00
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static bool has_vnet_hdr(int fd)
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{
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unsigned int features = 0;
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if (ioctl(fd, TUNGETFEATURES, &features) == -1) {
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return false;
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}
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if (!(features & IFF_VNET_HDR)) {
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return false;
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}
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return true;
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}
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static void prep_ifreq(struct ifreq *ifr, const char *ifname)
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{
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memset(ifr, 0, sizeof(*ifr));
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snprintf(ifr->ifr_name, IFNAMSIZ, "%s", ifname);
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}
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static int send_fd(int c, int fd)
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{
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char msgbuf[CMSG_SPACE(sizeof(fd))];
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struct msghdr msg = {
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.msg_control = msgbuf,
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.msg_controllen = sizeof(msgbuf),
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};
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struct cmsghdr *cmsg;
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struct iovec iov;
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char req[1] = { 0x00 };
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cmsg = CMSG_FIRSTHDR(&msg);
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cmsg->cmsg_level = SOL_SOCKET;
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cmsg->cmsg_type = SCM_RIGHTS;
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cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
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msg.msg_controllen = cmsg->cmsg_len;
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iov.iov_base = req;
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iov.iov_len = sizeof(req);
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msg.msg_iov = &iov;
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msg.msg_iovlen = 1;
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memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd));
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return sendmsg(c, &msg, 0);
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}
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2012-01-26 14:42:26 +00:00
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#ifdef CONFIG_LIBCAP
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static int drop_privileges(void)
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{
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/* clear all capabilities */
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capng_clear(CAPNG_SELECT_BOTH);
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if (capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED,
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CAP_NET_ADMIN) < 0) {
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return -1;
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}
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/* change to calling user's real uid and gid, retaining supplemental
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* groups and CAP_NET_ADMIN */
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if (capng_change_id(getuid(), getgid(), CAPNG_CLEAR_BOUNDING)) {
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return -1;
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}
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return 0;
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}
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#endif
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2012-01-26 14:42:24 +00:00
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int main(int argc, char **argv)
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{
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struct ifreq ifr;
|
2012-07-12 13:24:31 +00:00
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#ifndef SIOCBRADDIF
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unsigned long ifargs[4];
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#endif
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int ifindex;
|
2014-06-10 09:20:25 +00:00
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int fd = -1, ctlfd = -1, unixfd = -1;
|
2012-01-26 14:42:24 +00:00
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int use_vnet = 0;
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int mtu;
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const char *bridge = NULL;
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char iface[IFNAMSIZ];
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int index;
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2012-01-26 14:42:25 +00:00
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ACLRule *acl_rule;
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ACLList acl_list;
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int access_allowed, access_denied;
|
2012-01-26 14:42:24 +00:00
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int ret = EXIT_SUCCESS;
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2012-01-26 14:42:26 +00:00
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#ifdef CONFIG_LIBCAP
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/* if we're run from an suid binary, immediately drop privileges preserving
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* cap_net_admin */
|
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if (geteuid() == 0 && getuid() != geteuid()) {
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|
|
if (drop_privileges() == -1) {
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|
fprintf(stderr, "failed to drop privileges\n");
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return 1;
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|
}
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}
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#endif
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2012-01-26 14:42:24 +00:00
|
|
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/* parse arguments */
|
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for (index = 1; index < argc; index++) {
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|
|
if (strcmp(argv[index], "--use-vnet") == 0) {
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use_vnet = 1;
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|
|
} else if (strncmp(argv[index], "--br=", 5) == 0) {
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bridge = &argv[index][5];
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} else if (strncmp(argv[index], "--fd=", 5) == 0) {
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unixfd = atoi(&argv[index][5]);
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|
|
} else {
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|
|
usage();
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|
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return EXIT_FAILURE;
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|
|
}
|
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|
|
}
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|
|
|
|
|
if (bridge == NULL || unixfd == -1) {
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|
|
usage();
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return EXIT_FAILURE;
|
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|
|
}
|
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|
2012-01-26 14:42:25 +00:00
|
|
|
/* parse default acl file */
|
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|
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QSIMPLEQ_INIT(&acl_list);
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|
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if (parse_acl_file(DEFAULT_ACL_FILE, &acl_list) == -1) {
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|
|
fprintf(stderr, "failed to parse default acl file `%s'\n",
|
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|
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DEFAULT_ACL_FILE);
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|
|
ret = EXIT_FAILURE;
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|
|
goto cleanup;
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|
|
}
|
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|
|
|
|
|
|
/* validate bridge against acl -- default policy is to deny
|
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|
|
* according acl policy if we have a deny and allow both
|
|
|
|
* then deny should always win over allow
|
|
|
|
*/
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|
|
access_allowed = 0;
|
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|
|
access_denied = 0;
|
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|
|
QSIMPLEQ_FOREACH(acl_rule, &acl_list, entry) {
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|
|
|
switch (acl_rule->type) {
|
|
|
|
case ACL_ALLOW_ALL:
|
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|
|
access_allowed = 1;
|
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|
|
break;
|
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|
|
case ACL_ALLOW:
|
|
|
|
if (strcmp(bridge, acl_rule->iface) == 0) {
|
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|
|
access_allowed = 1;
|
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|
|
}
|
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|
|
break;
|
|
|
|
case ACL_DENY_ALL:
|
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|
|
access_denied = 1;
|
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|
|
break;
|
|
|
|
case ACL_DENY:
|
|
|
|
if (strcmp(bridge, acl_rule->iface) == 0) {
|
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|
|
access_denied = 1;
|
|
|
|
}
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
if ((access_allowed == 0) || (access_denied == 1)) {
|
|
|
|
fprintf(stderr, "access denied by acl file\n");
|
|
|
|
ret = EXIT_FAILURE;
|
|
|
|
goto cleanup;
|
|
|
|
}
|
|
|
|
|
2012-01-26 14:42:24 +00:00
|
|
|
/* open a socket to use to control the network interfaces */
|
|
|
|
ctlfd = socket(AF_INET, SOCK_STREAM, 0);
|
|
|
|
if (ctlfd == -1) {
|
|
|
|
fprintf(stderr, "failed to open control socket: %s\n", strerror(errno));
|
|
|
|
ret = EXIT_FAILURE;
|
|
|
|
goto cleanup;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* open the tap device */
|
|
|
|
fd = open("/dev/net/tun", O_RDWR);
|
|
|
|
if (fd == -1) {
|
|
|
|
fprintf(stderr, "failed to open /dev/net/tun: %s\n", strerror(errno));
|
|
|
|
ret = EXIT_FAILURE;
|
|
|
|
goto cleanup;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* request a tap device, disable PI, and add vnet header support if
|
|
|
|
* requested and it's available. */
|
|
|
|
prep_ifreq(&ifr, "tap%d");
|
|
|
|
ifr.ifr_flags = IFF_TAP|IFF_NO_PI;
|
|
|
|
if (use_vnet && has_vnet_hdr(fd)) {
|
|
|
|
ifr.ifr_flags |= IFF_VNET_HDR;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (ioctl(fd, TUNSETIFF, &ifr) == -1) {
|
|
|
|
fprintf(stderr, "failed to create tun device: %s\n", strerror(errno));
|
|
|
|
ret = EXIT_FAILURE;
|
|
|
|
goto cleanup;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* save tap device name */
|
|
|
|
snprintf(iface, sizeof(iface), "%s", ifr.ifr_name);
|
|
|
|
|
|
|
|
/* get the mtu of the bridge */
|
|
|
|
prep_ifreq(&ifr, bridge);
|
|
|
|
if (ioctl(ctlfd, SIOCGIFMTU, &ifr) == -1) {
|
|
|
|
fprintf(stderr, "failed to get mtu of bridge `%s': %s\n",
|
|
|
|
bridge, strerror(errno));
|
|
|
|
ret = EXIT_FAILURE;
|
|
|
|
goto cleanup;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* save mtu */
|
|
|
|
mtu = ifr.ifr_mtu;
|
|
|
|
|
|
|
|
/* set the mtu of the interface based on the bridge */
|
|
|
|
prep_ifreq(&ifr, iface);
|
|
|
|
ifr.ifr_mtu = mtu;
|
|
|
|
if (ioctl(ctlfd, SIOCSIFMTU, &ifr) == -1) {
|
|
|
|
fprintf(stderr, "failed to set mtu of device `%s' to %d: %s\n",
|
|
|
|
iface, mtu, strerror(errno));
|
|
|
|
ret = EXIT_FAILURE;
|
|
|
|
goto cleanup;
|
|
|
|
}
|
|
|
|
|
2013-03-22 16:57:48 +00:00
|
|
|
/* Linux uses the lowest enslaved MAC address as the MAC address of
|
|
|
|
* the bridge. Set MAC address to a high value so that it doesn't
|
|
|
|
* affect the MAC address of the bridge.
|
|
|
|
*/
|
|
|
|
if (ioctl(ctlfd, SIOCGIFHWADDR, &ifr) < 0) {
|
|
|
|
fprintf(stderr, "failed to get MAC address of device `%s': %s\n",
|
|
|
|
iface, strerror(errno));
|
|
|
|
ret = EXIT_FAILURE;
|
|
|
|
goto cleanup;
|
|
|
|
}
|
|
|
|
ifr.ifr_hwaddr.sa_data[0] = 0xFE;
|
|
|
|
if (ioctl(ctlfd, SIOCSIFHWADDR, &ifr) < 0) {
|
|
|
|
fprintf(stderr, "failed to set MAC address of device `%s': %s\n",
|
|
|
|
iface, strerror(errno));
|
|
|
|
ret = EXIT_FAILURE;
|
|
|
|
goto cleanup;
|
|
|
|
}
|
|
|
|
|
2012-01-26 14:42:24 +00:00
|
|
|
/* add the interface to the bridge */
|
|
|
|
prep_ifreq(&ifr, bridge);
|
2012-07-12 13:24:31 +00:00
|
|
|
ifindex = if_nametoindex(iface);
|
|
|
|
#ifndef SIOCBRADDIF
|
|
|
|
ifargs[0] = BRCTL_ADD_IF;
|
|
|
|
ifargs[1] = ifindex;
|
|
|
|
ifargs[2] = 0;
|
|
|
|
ifargs[3] = 0;
|
|
|
|
ifr.ifr_data = (void *)ifargs;
|
|
|
|
ret = ioctl(ctlfd, SIOCDEVPRIVATE, &ifr);
|
|
|
|
#else
|
|
|
|
ifr.ifr_ifindex = ifindex;
|
|
|
|
ret = ioctl(ctlfd, SIOCBRADDIF, &ifr);
|
|
|
|
#endif
|
|
|
|
if (ret == -1) {
|
2012-01-26 14:42:24 +00:00
|
|
|
fprintf(stderr, "failed to add interface `%s' to bridge `%s': %s\n",
|
|
|
|
iface, bridge, strerror(errno));
|
|
|
|
ret = EXIT_FAILURE;
|
|
|
|
goto cleanup;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* bring the interface up */
|
|
|
|
prep_ifreq(&ifr, iface);
|
|
|
|
if (ioctl(ctlfd, SIOCGIFFLAGS, &ifr) == -1) {
|
|
|
|
fprintf(stderr, "failed to get interface flags for `%s': %s\n",
|
|
|
|
iface, strerror(errno));
|
|
|
|
ret = EXIT_FAILURE;
|
|
|
|
goto cleanup;
|
|
|
|
}
|
|
|
|
|
|
|
|
ifr.ifr_flags |= IFF_UP;
|
|
|
|
if (ioctl(ctlfd, SIOCSIFFLAGS, &ifr) == -1) {
|
|
|
|
fprintf(stderr, "failed to bring up interface `%s': %s\n",
|
|
|
|
iface, strerror(errno));
|
|
|
|
ret = EXIT_FAILURE;
|
|
|
|
goto cleanup;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* write fd to the domain socket */
|
|
|
|
if (send_fd(unixfd, fd) == -1) {
|
|
|
|
fprintf(stderr, "failed to write fd to unix socket: %s\n",
|
|
|
|
strerror(errno));
|
|
|
|
ret = EXIT_FAILURE;
|
|
|
|
goto cleanup;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* ... */
|
|
|
|
|
|
|
|
/* profit! */
|
|
|
|
|
|
|
|
cleanup:
|
2014-06-10 09:20:25 +00:00
|
|
|
if (fd >= 0) {
|
|
|
|
close(fd);
|
|
|
|
}
|
|
|
|
if (ctlfd >= 0) {
|
|
|
|
close(ctlfd);
|
|
|
|
}
|
2012-01-26 14:42:25 +00:00
|
|
|
while ((acl_rule = QSIMPLEQ_FIRST(&acl_list)) != NULL) {
|
|
|
|
QSIMPLEQ_REMOVE_HEAD(&acl_list, entry);
|
|
|
|
g_free(acl_rule);
|
|
|
|
}
|
|
|
|
|
2012-01-26 14:42:24 +00:00
|
|
|
return ret;
|
|
|
|
}
|