*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
- *
*/
-#include "config-host.h"
+/*
+ * Known shortcomings:
+ * - There is no manual page
+ * - The syntax of the ACL file is not documented anywhere
+ * - parse_acl_file() doesn't report fopen() failure properly, fails
+ * to check ferror() after fgets() failure, arbitrarily truncates
+ * long lines, handles whitespace inconsistently, error messages
+ * don't point to the offending file and line, errors in included
+ * files are reported, but otherwise ignored, ...
+ */
+
+#include "qemu/osdep.h"
-#include <stdio.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <string.h>
-#include <stdlib.h>
-#include <stdbool.h>
-#include <ctype.h>
-#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <linux/sockios.h>
+#ifndef SIOCBRADDIF
+#include <linux/if_bridge.h>
+#endif
+
+#include "qemu/queue.h"
+
#include "net/tap-linux.h"
+#ifdef CONFIG_LIBCAP
+#include <cap-ng.h>
+#endif
+
+#define DEFAULT_ACL_FILE CONFIG_QEMU_CONFDIR "/bridge.conf"
+
+enum {
+ ACL_ALLOW = 0,
+ ACL_ALLOW_ALL,
+ ACL_DENY,
+ ACL_DENY_ALL,
+};
+
+typedef struct ACLRule {
+ int type;
+ char iface[IFNAMSIZ];
+ QSIMPLEQ_ENTRY(ACLRule) entry;
+} ACLRule;
+
+typedef QSIMPLEQ_HEAD(ACLList, ACLRule) ACLList;
+
static void usage(void)
{
fprintf(stderr,
"Usage: qemu-bridge-helper [--use-vnet] --br=bridge --fd=unixfd\n");
}
+static int parse_acl_file(const char *filename, ACLList *acl_list)
+{
+ FILE *f;
+ char line[4096];
+ ACLRule *acl_rule;
+
+ f = fopen(filename, "r");
+ if (f == NULL) {
+ return -1;
+ }
+
+ while (fgets(line, sizeof(line), f) != NULL) {
+ char *ptr = line;
+ char *cmd, *arg, *argend;
+
+ while (g_ascii_isspace(*ptr)) {
+ ptr++;
+ }
+
+ /* skip comments and empty lines */
+ if (*ptr == '#' || *ptr == 0) {
+ continue;
+ }
+
+ cmd = ptr;
+ arg = strchr(cmd, ' ');
+ if (arg == NULL) {
+ arg = strchr(cmd, '\t');
+ }
+
+ if (arg == NULL) {
+ fprintf(stderr, "Invalid config line:\n %s\n", line);
+ fclose(f);
+ errno = EINVAL;
+ return -1;
+ }
+
+ *arg = 0;
+ arg++;
+ while (g_ascii_isspace(*arg)) {
+ arg++;
+ }
+
+ argend = arg + strlen(arg);
+ while (arg != argend && g_ascii_isspace(*(argend - 1))) {
+ argend--;
+ }
+ *argend = 0;
+
+ if (strcmp(cmd, "deny") == 0) {
+ acl_rule = g_malloc(sizeof(*acl_rule));
+ if (strcmp(arg, "all") == 0) {
+ acl_rule->type = ACL_DENY_ALL;
+ } else {
+ acl_rule->type = ACL_DENY;
+ snprintf(acl_rule->iface, IFNAMSIZ, "%s", arg);
+ }
+ QSIMPLEQ_INSERT_TAIL(acl_list, acl_rule, entry);
+ } else if (strcmp(cmd, "allow") == 0) {
+ acl_rule = g_malloc(sizeof(*acl_rule));
+ if (strcmp(arg, "all") == 0) {
+ acl_rule->type = ACL_ALLOW_ALL;
+ } else {
+ acl_rule->type = ACL_ALLOW;
+ snprintf(acl_rule->iface, IFNAMSIZ, "%s", arg);
+ }
+ QSIMPLEQ_INSERT_TAIL(acl_list, acl_rule, entry);
+ } else if (strcmp(cmd, "include") == 0) {
+ /* ignore errors */
+ parse_acl_file(arg, acl_list);
+ } else {
+ fprintf(stderr, "Unknown command `%s'\n", cmd);
+ fclose(f);
+ errno = EINVAL;
+ return -1;
+ }
+ }
+
+ fclose(f);
+
+ return 0;
+}
+
static bool has_vnet_hdr(int fd)
{
unsigned int features = 0;
return sendmsg(c, &msg, 0);
}
+#ifdef CONFIG_LIBCAP
+static int drop_privileges(void)
+{
+ /* clear all capabilities */
+ capng_clear(CAPNG_SELECT_BOTH);
+
+ if (capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED,
+ CAP_NET_ADMIN) < 0) {
+ return -1;
+ }
+
+ /* change to calling user's real uid and gid, retaining supplemental
+ * groups and CAP_NET_ADMIN */
+ if (capng_change_id(getuid(), getgid(), CAPNG_CLEAR_BOUNDING)) {
+ return -1;
+ }
+
+ return 0;
+}
+#endif
+
int main(int argc, char **argv)
{
struct ifreq ifr;
- int fd, ctlfd, unixfd = -1;
+#ifndef SIOCBRADDIF
+ unsigned long ifargs[4];
+#endif
+ int ifindex;
+ int fd = -1, ctlfd = -1, unixfd = -1;
int use_vnet = 0;
int mtu;
const char *bridge = NULL;
char iface[IFNAMSIZ];
int index;
+ ACLRule *acl_rule;
+ ACLList acl_list;
+ int access_allowed, access_denied;
int ret = EXIT_SUCCESS;
+#ifdef CONFIG_LIBCAP
+ /* if we're run from an suid binary, immediately drop privileges preserving
+ * cap_net_admin */
+ if (geteuid() == 0 && getuid() != geteuid()) {
+ if (drop_privileges() == -1) {
+ fprintf(stderr, "failed to drop privileges\n");
+ return 1;
+ }
+ }
+#endif
+
/* parse arguments */
for (index = 1; index < argc; index++) {
if (strcmp(argv[index], "--use-vnet") == 0) {
return EXIT_FAILURE;
}
+ /* parse default acl file */
+ QSIMPLEQ_INIT(&acl_list);
+ if (parse_acl_file(DEFAULT_ACL_FILE, &acl_list) == -1) {
+ fprintf(stderr, "failed to parse default acl file `%s'\n",
+ DEFAULT_ACL_FILE);
+ ret = EXIT_FAILURE;
+ goto cleanup;
+ }
+
+ /* validate bridge against acl -- default policy is to deny
+ * according acl policy if we have a deny and allow both
+ * then deny should always win over allow
+ */
+ access_allowed = 0;
+ access_denied = 0;
+ QSIMPLEQ_FOREACH(acl_rule, &acl_list, entry) {
+ switch (acl_rule->type) {
+ case ACL_ALLOW_ALL:
+ access_allowed = 1;
+ break;
+ case ACL_ALLOW:
+ if (strcmp(bridge, acl_rule->iface) == 0) {
+ access_allowed = 1;
+ }
+ break;
+ case ACL_DENY_ALL:
+ access_denied = 1;
+ break;
+ case ACL_DENY:
+ if (strcmp(bridge, acl_rule->iface) == 0) {
+ access_denied = 1;
+ }
+ break;
+ }
+ }
+
+ if ((access_allowed == 0) || (access_denied == 1)) {
+ fprintf(stderr, "access denied by acl file\n");
+ ret = EXIT_FAILURE;
+ goto cleanup;
+ }
+
/* open a socket to use to control the network interfaces */
ctlfd = socket(AF_INET, SOCK_STREAM, 0);
if (ctlfd == -1) {
goto cleanup;
}
+ /* 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;
+ }
+
/* add the interface to the bridge */
prep_ifreq(&ifr, bridge);
- ifr.ifr_ifindex = if_nametoindex(iface);
-
- if (ioctl(ctlfd, SIOCBRADDIF, &ifr) == -1) {
+ 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) {
fprintf(stderr, "failed to add interface `%s' to bridge `%s': %s\n",
iface, bridge, strerror(errno));
ret = EXIT_FAILURE;
/* profit! */
cleanup:
+ if (fd >= 0) {
+ close(fd);
+ }
+ if (ctlfd >= 0) {
+ close(ctlfd);
+ }
+ while ((acl_rule = QSIMPLEQ_FIRST(&acl_list)) != NULL) {
+ QSIMPLEQ_REMOVE_HEAD(&acl_list, entry);
+ g_free(acl_rule);
+ }
return ret;
}
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