--- /dev/null
+/*
+ * QEMU Bridge Helper
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ * Anthony Liguori <aliguori@us.ibm.com>
+ * Richa Marwaha <rmarwah@linux.vnet.ibm.com>
+ * Corey Bryant <coreyb@linux.vnet.ibm.com>
+ *
+ * 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"
+
+#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 <glib.h>
+
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/prctl.h>
+
+#include <net/if.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 (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 (isspace(*arg)) {
+ arg++;
+ }
+
+ argend = arg + strlen(arg);
+ while (arg != argend && 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;
+
+ if (ioctl(fd, TUNGETFEATURES, &features) == -1) {
+ return false;
+ }
+
+ if (!(features & IFF_VNET_HDR)) {
+ return false;
+ }
+
+ return true;
+}
+
+static void prep_ifreq(struct ifreq *ifr, const char *ifname)
+{
+ memset(ifr, 0, sizeof(*ifr));
+ snprintf(ifr->ifr_name, IFNAMSIZ, "%s", ifname);
+}
+
+static int send_fd(int c, int fd)
+{
+ char msgbuf[CMSG_SPACE(sizeof(fd))];
+ struct msghdr msg = {
+ .msg_control = msgbuf,
+ .msg_controllen = sizeof(msgbuf),
+ };
+ struct cmsghdr *cmsg;
+ struct iovec iov;
+ char req[1] = { 0x00 };
+
+ cmsg = CMSG_FIRSTHDR(&msg);
+ cmsg->cmsg_level = SOL_SOCKET;
+ cmsg->cmsg_type = SCM_RIGHTS;
+ cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
+ msg.msg_controllen = cmsg->cmsg_len;
+
+ iov.iov_base = req;
+ iov.iov_len = sizeof(req);
+
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+ memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd));
+
+ 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;
+#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) {
+ use_vnet = 1;
+ } else if (strncmp(argv[index], "--br=", 5) == 0) {
+ bridge = &argv[index][5];
+ } else if (strncmp(argv[index], "--fd=", 5) == 0) {
+ unixfd = atoi(&argv[index][5]);
+ } else {
+ usage();
+ return EXIT_FAILURE;
+ }
+ }
+
+ if (bridge == NULL || unixfd == -1) {
+ usage();
+ 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) {
+ 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;
+ }
+
+ /* 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);
+ 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;
+ 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:
+ 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;
+}
Code Review / kvmfornfv.git / blobdiff