X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=userv-utils.git;a=blobdiff_plain;f=ipif%2Fservice.c;h=eacfc63c1ce4d9782d7823716ec5b71281c55f13;hp=df039269cf19297b2f09dceba9a0866ca88e39d4;hb=f2add8c1b19c46ff78655278643c3c2851db7566;hpb=0324503152d6edb67572b45225745441913ae55e

diff --git a/ipif/service.c b/ipif/service.c
index df03926..eacfc63 100644
--- a/ipif/service.c
+++ b/ipif/service.c
@@ -30,7 +30,7 @@
  *
  *  The remaining arguments are supplied by the (untrusted) caller:
  *
- *  <local-addr>,<peer-addr>,<mtu>,<proto>
+ *  <local-addr>,<peer-addr>,<mtu>[,[<proto>][,[<ifnamepat>]]]
  *
  *      As for slattach.  The only supported protocol is slip.
  *      Alternatively, set to `debug' to print debugging info and
@@ -82,6 +82,9 @@
  *      service program directly (not via userv), without needing to set up
  *      permissions in /etc/userv/ipif-networks.
  *
+ *      Only `*' permits interface name patterns other than the default
+ *      value of `userv%d'.
+ *
  *   #...
  *
  *      Comment.  Blank lines are also ignored.
@@ -125,6 +128,7 @@
 #include <unistd.h>
 #include <stdint.h>
 #include <poll.h>
+#include <stddef.h>
 
 #include <sys/types.h>
 #include <sys/wait.h>
@@ -147,11 +151,13 @@
 static const unsigned long gidmaxval= (unsigned long)((gid_t)-2);
 static const char *const protos_ok[]= { "slip", 0 };
 static const int signals[]= { SIGHUP, SIGINT, SIGTERM, 0 };
+static const char default_ifnamepat[]= "userv%d";
 
 static const char *configstr, *proto;
 static unsigned long localaddr, peeraddr, mtu;
 static int localpming, peerpming;
-static int localallow, peerallow, allallow;
+static int localallow, peerallow, ifnameallow, allallow;
+static char *ifnamepat;
 static int nexroutes;
 static struct exroute {
   unsigned long prefix, mask;
@@ -323,6 +329,34 @@ static void eat_prefixmask(const char **argp, const char *what,
   if (len_r) *len_r= len;
 }
 
+static char *eat_optionalstr(const char **argp,
+			     const char *what,
+			     const char *def) {
+  ptrdiff_t len;
+  const char *start= *argp;
+  if (!start) {
+    len = 0;
+  } else {
+    const char *comma= strchr(start, ',');
+    if (comma) {
+      len= comma - start;
+      *argp= comma + 1;
+    } else {
+      len= strlen(start);
+      *argp= 0;
+    }
+  }
+  if (!len) {
+    start= def;
+    len= strlen(def);
+  }
+  char *r = malloc(len+1);
+  if (!r) sysfatal("malloc for command line string");
+  memcpy(r,start,len);
+  r[len]= 0;
+  return r;
+}
+
 static int addrnet_isin(unsigned long prefix, unsigned long mask,
 			unsigned long mprefix, unsigned long mmask) {
   return  !(~mask & mmask)  &&  (prefix & mmask) == mprefix;
@@ -447,6 +481,7 @@ static void pconfig(const char *configstr, int truncated) {
   case '*':
     permit_begin();
     permit_range(0UL,0UL,1,0);
+    ifnameallow= 1;
     return;
     
   case '#':
@@ -545,15 +580,18 @@ static void parseargs(int argc, const char *const *argv) {
   peeraddr= eat_addr(&carg,"peer-addr", ",",0);
   mtu= eat_number(&carg,"mtu", 576,65536, ",",0);
   localallow= peerallow= 0;
-  
-  if (!strcmp(carg,"debug")) {
+
+  char *protostr= eat_optionalstr(&carg,"protocol","slip");
+  if (!strcmp(protostr,"debug")) {
     proto= 0;
   } else {
     for (cprotop= protos_ok;
-	 (proto= *cprotop) && strcmp(proto,carg);
+	 (proto= *cprotop) && strcmp(proto,protostr);
 	 cprotop++);
     if (!proto) fatal("invalid protocol");
   }
+
+  ifnamepat= eat_optionalstr(&carg,"ifname pattern",default_ifnamepat);
   
   addrnet_mustdiffer("local-addr",localaddr,~0UL, "peer-addr",peeraddr,~0UL);
   
@@ -599,6 +637,14 @@ static void checkpermit(void) {
     sprintf(erwhatbuf, "route#%d", i);
     checkallow(exroutes[i].allow, erwhatbuf, exroutes[i].prefixtxt, exroutes[i].masktxt);
   }
+  if (!strcmp(ifnamepat,default_ifnamepat))
+    ifnameallow= 1;
+  if (!ifnameallow) {
+    fprintf(stderr,
+	    "userv-ipif service: access denied for interface name %s\n",
+	    ifnamepat);
+    allallow= 0;
+  }
   if (!allallow) fatal("access denied");
 }
 
@@ -661,14 +707,13 @@ static int task(const char *desc) {
 }
 
 static void createif(void) {
-  static const char ifnamepat[]= "userv%d";
   struct ifreq ifr;
   int r;
 
   memset(&ifr,0,sizeof(ifr));
   ifr.ifr_flags= IFF_TUN | IFF_NO_PI;
 
-  assert(sizeof(ifr.ifr_name) >= sizeof(ifnamepat));
+  assert(sizeof(ifr.ifr_name) >= strlen(ifnamepat)+1);
   strcpy(ifr.ifr_name, ifnamepat);
 
   tunfd= open("/dev/net/tun", O_RDWR);