tunctl: Added an tunctl which supports TUNSETGROUP

TUNSETGROUP is needed in order to preconfigure a set of tap devices
that can be used by non-root users.  The requirement is that the qemu
users be members of whatever group the tap devices are assigned to.

Include tunctl in the qemu-helper package, and add a -native version.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Scott Garman <scott.a.garman@intel.com>

1 files changed, 156 insertions, 0 deletions

diff --git a/meta/packages/qemu/qemu-helper/tunctl.c b/meta/packages/qemu/qemu-helper/tunctl.c
new file mode 100644
index 0000000000..16e24a2add
--- /dev/null
+++ b/meta/packages/qemu/qemu-helper/tunctl.c
@@ -0,0 +1,156 @@
+/* Copyright 2002 Jeff Dike
+ * Licensed under the GPL
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <pwd.h>
+#include <grp.h>
+#include <net/if.h>
+#include <sys/ioctl.h>
+#include <linux/if_tun.h>
+
+/* TUNSETGROUP appeared in 2.6.23 */
+#ifndef TUNSETGROUP
+#define TUNSETGROUP   _IOW('T', 206, int)
+#endif
+
+static void Usage(char *name)
+{
+  fprintf(stderr, "Create: %s [-b] [-u owner] [-g group] [-t device-name] "
+          "[-f tun-clone-device]\n", name);
+  fprintf(stderr, "Delete: %s -d device-name [-f tun-clone-device]\n\n",
+          name);
+  fprintf(stderr, "The default tun clone device is /dev/net/tun - some systems"
+          " use\n/dev/misc/net/tun instead\n\n");
+  fprintf(stderr, "-b will result in brief output (just the device name)\n");
+  exit(1);
+}
+
+int main(int argc, char **argv)
+{
+  struct ifreq ifr;
+  struct passwd *pw;
+  struct group *gr;
+  uid_t owner = -1;
+  gid_t group = -1;
+  int tap_fd, opt, delete = 0, brief = 0;
+  char *tun = "", *file = "/dev/net/tun", *name = argv[0], *end;
+
+  while((opt = getopt(argc, argv, "bd:f:t:u:g:")) > 0){
+    switch(opt) {
+      case 'b':
+        brief = 1;
+        break;
+      case 'd':
+        delete = 1;
+        tun = optarg;
+        break;
+      case 'f':
+        file = optarg;
+        break;
+      case 'u':
+        pw = getpwnam(optarg);
+        if(pw != NULL){
+          owner = pw->pw_uid;
+          break;
+        }
+        owner = strtol(optarg, &end, 0);
+        if(*end != '\0'){
+          fprintf(stderr, "'%s' is neither a username nor a numeric uid.\n",
+                  optarg);
+          Usage(name);
+        }
+        break;
+      case 'g':
+        gr = getgrnam(optarg);
+        if(gr != NULL){
+          group = gr->gr_gid;
+          break;
+        }
+        group = strtol(optarg, &end, 0);
+        if(*end != '\0'){
+          fprintf(stderr, "'%s' is neither a groupname nor a numeric group.\n",
+                  optarg);
+          Usage(name);
+        }
+        break;
+
+      case 't':
+        tun = optarg;
+        break;
+      case 'h':
+      default:
+        Usage(name);
+    }
+  }
+
+  argv += optind;
+  argc -= optind;
+
+  if(argc > 0)
+    Usage(name);
+
+  if((tap_fd = open(file, O_RDWR)) < 0){
+    fprintf(stderr, "Failed to open '%s' : ", file);
+    perror("");
+    exit(1);
+  }
+
+  memset(&ifr, 0, sizeof(ifr));
+
+  ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
+  strncpy(ifr.ifr_name, tun, sizeof(ifr.ifr_name) - 1);
+  if(ioctl(tap_fd, TUNSETIFF, (void *) &ifr) < 0){
+    perror("TUNSETIFF");
+    exit(1);
+  }
+
+  if(delete){
+    if(ioctl(tap_fd, TUNSETPERSIST, 0) < 0){
+      perror("disabling TUNSETPERSIST");
+      exit(1);
+    }
+    printf("Set '%s' nonpersistent\n", ifr.ifr_name);
+  }
+  else {
+    /* emulate behaviour prior to TUNSETGROUP */
+    if(owner == -1 && group == -1) {
+      owner = geteuid();
+    }
+
+    if(owner != -1) {
+      if(ioctl(tap_fd, TUNSETOWNER, owner) < 0){
+        perror("TUNSETOWNER");
+        exit(1);
+      }
+    }
+    if(group != -1) {
+      if(ioctl(tap_fd, TUNSETGROUP, group) < 0){
+        perror("TUNSETGROUP");
+        exit(1);
+      }
+    }
+
+    if(ioctl(tap_fd, TUNSETPERSIST, 1) < 0){
+      perror("enabling TUNSETPERSIST");
+      exit(1);
+    }
+
+    if(brief)
+      printf("%s\n", ifr.ifr_name);
+    else {
+      printf("Set '%s' persistent and owned by", ifr.ifr_name);
+      if(owner != -1)
+          printf(" uid %d", owner);
+      if(group != -1)
+          printf(" gid %d", group);
+      printf("\n");
+    }
+  }
+  return(0);
+}