Try to autoload ebtables kernel module when needed.

diff --git a/ebtables.c b/ebtables.c
index dddb623..061ed4d 100644 (file)
--- a/ebtables.c
+++ b/ebtables.c
@@ -34,11 +34,22 @@
 #include <netinet/ether.h>
 #include <asm/types.h>
 #include "include/ebtables_u.h"
+#include <dlfcn.h>
+#include <ctype.h>
+#include <stdarg.h>
+#include <limits.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/wait.h>
 
 // here are the number-name correspondences kept for the ethernet
 // frame type field
 #define PROTOCOLFILE "/etc/ethertypes"
 
+#ifndef PROC_SYS_MODPROBE
+#define PROC_SYS_MODPROBE "/proc/sys/kernel/modprobe"
+#endif
+
 #define DATABASEHOOKNR NF_BR_NUMHOOKS
 #define DATABASEHOOKNAME "DB"
 
@@ -79,6 +90,7 @@ static struct option ebt_original_options[] = {
        { "destination"   , required_argument, 0, 'd' },
        { "dst"           , required_argument, 0, 'd' },
        { "table"         , required_argument, 0, 't' },
+       { "modprobe"      , required_argument, 0, 'M' },
        { 0 }
 };
 
@@ -326,6 +338,69 @@ void register_table(struct ebt_u_table *t)
        tables = t;
 }
 
+// blatently stolen (again) from iptables.c userspace program
+// find out where the modprobe utility is located
+static char *get_modprobe(void)
+{
+       int procfile;
+       char *ret;
+
+       procfile = open(PROC_SYS_MODPROBE, O_RDONLY);
+       if (procfile < 0)
+               return NULL;
+
+       ret = malloc(1024);
+       if (ret) {
+               switch (read(procfile, ret, 1024)) {
+               case -1: goto fail;
+               case 1024: goto fail; /* Partial read.  Wierd */
+               }
+               if (ret[strlen(ret)-1]=='\n')
+                       ret[strlen(ret)-1]=0;
+               close(procfile);
+               return ret;
+       }
+ fail:
+       free(ret);
+       close(procfile);
+       return NULL;
+}
+
+// I hate stealing, really... Lets call it a tribute.
+int ebtables_insmod(const char *modname, const char *modprobe)
+{
+       char *buf = NULL;
+       char *argv[3];
+
+       /* If they don't explicitly set it, read out of kernel */
+       if (!modprobe) {
+               buf = get_modprobe();
+               if (!buf)
+                       return -1;
+               modprobe = buf;
+       }
+
+       switch (fork()) {
+       case 0:
+               argv[0] = (char *)modprobe;
+               argv[1] = (char *)modname;
+               argv[2] = NULL;
+               execv(argv[0], argv);
+
+               /* not usually reached */
+               exit(0);
+       case -1:
+               return -1;
+
+       default: /* parent */
+               wait(NULL);
+       }
+
+       free(buf);
+       return 0;
+}
+
+
 // used to parse /etc/etherproto
 int disregard_whitespace(char *buffer, FILE *ifp)
 {
@@ -631,6 +706,7 @@ void print_help()
 "--out-if -o [!] name          : network output interface name\n"
 "--logical-in  [!] name        : logical bridge input interface name\n"
 "--logical-out [!] name        : logical bridge output interface name\n"
+"--modprobe -M                 : try to insert modules using this command\n"
 "--version -V                  : print package version\n"
 "\n" ,
        prog_name,
@@ -1206,6 +1282,7 @@ int main(int argc, char *argv[])
        struct ebt_u_watcher *w;
        struct ebt_u_match_list *m_l;
        struct ebt_u_watcher_list *w_l;
+       const char *modprobe = NULL;
 
        // initialize the table name, OPT_ flags, selected hook and command
        strcpy(replace.name, "filter");
@@ -1221,7 +1298,7 @@ int main(int argc, char *argv[])
 
        // getopt saves the day
        while ((c = getopt_long(argc, argv,
-          "-A:D:I:L::Z::F::P:Vhi:o:j:p:b:s:d:t:", ebt_options, NULL)) != -1) {
+          "-A:D:I:L::Z::F::P:Vhi:o:j:p:b:s:d:t:M:", ebt_options, NULL)) != -1) {
                switch (c) {
 
                case 'A': // add a rule
@@ -1312,6 +1389,10 @@ int main(int argc, char *argv[])
                        printf("%s, %s\n", prog_name, prog_version);
                        exit(0);
 
+               case 'M': // modprobe
+                       modprobe = optarg;
+                       break;
+
                case 'h': // help
                        if (replace.flags & OPT_COMMAND)
                                print_error("Multiple commands not allowed");
@@ -1600,7 +1681,12 @@ int main(int argc, char *argv[])
        new_entry->ethproto = htons(new_entry->ethproto);
 
        // get the kernel's information
-       get_table(&replace);
+       if (get_table(&replace)) {
+               ebtables_insmod("ebtables", modprobe);
+               if (get_table(&replace))
+                       print_error("can't initialize ebtables table %s",
+                       replace.name);
+       }
        // check if selected_hook is a valid_hook
        if (replace.selected_hook >= 0 &&
           !(replace.valid_hooks & (1 << replace.selected_hook)))