mdw@git.distorted.org.uk Git - secnet/blob - random.c

   1 /*
   2  * This file is part of secnet.
   3  * See README for full list of copyright holders.
   4  *
   5  * secnet is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version d of the License, or
   8  * (at your option) any later version.
   9  *
  10  * secnet is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * version 3 along with secnet; if not, see
  17  * https://www.gnu.org/licenses/gpl.html.
  18  */
  19
  20 #include "secnet.h"
  21 #include <stdio.h>
  22 #include <fcntl.h>
  23 #include <string.h>
  24 #include <sys/stat.h>
  25 #include <unistd.h>
  26 #include <assert.h>
  27
  28 struct rgen_data {
  29     closure_t cl;
  30     struct random_if ops;
  31     struct cloc loc;
  32     int fd;
  33 };
  34
  35 static random_fn random_generate;
  36 static bool_t random_generate(void *data, int32_t bytes, uint8_t *buff)
  37 {
  38     struct rgen_data *st=data;
  39     int r;
  40
  41     r= read(st->fd,buff,bytes);
  42
  43     assert(r == bytes);
  44     /* This is totally crap error checking, but AFAICT many callers of
  45      * this function do not check the return value.  This is a minimal
  46      * change to make the code not fail silently-but-insecurely.
  47      *
  48      * A proper fix requires either:
  49      *  - Declare all random number generation failures as fatal
  50      *    errors, and make this return void, and fix all callers,
  51      *    and make this call some appropriate function if it fails.
  52      *  - Make this have proper error checking (and reporting!)
  53      *    and make all callers check the error (and report!);
  54      *    this will be tricky, I think, because you have to report
  55      *    the errno somewhere.
  56      *
  57      * There's also the issue that this is only one possible
  58      * implementation of a random number source; others may not rely
  59      * on reading from a file descriptor, and may not produce
  60      * appropriate settings of errno.
  61      */
  62
  63     return True;
  64 }
  65
  66 static list_t *random_apply(closure_t *self, struct cloc loc,
  67                             dict_t *context, list_t *args)
  68 {
  69     struct rgen_data *st;
  70     item_t *arg1, *arg2;
  71     string_t filename=NULL;
  72
  73     NEW(st);
  74
  75     st->cl.description="randomsource";
  76     st->cl.type=CL_RANDOMSRC;
  77     st->cl.apply=NULL;
  78     st->cl.interface=&st->ops;
  79     st->ops.st=st;
  80     st->ops.blocking=False;
  81     st->ops.generate=random_generate;
  82     st->loc=loc;
  83
  84     arg1=list_elem(args,0);
  85     arg2=list_elem(args,1);
  86
  87     if (!arg1) {
  88         cfgfatal(loc,"randomsource","requires a filename\n");
  89     }
  90     if (arg1->type != t_string) {
  91         cfgfatal(arg1->loc,"randomsource",
  92                  "filename (arg1) must be a string\n");
  93     }
  94     filename=arg1->data.string;
  95
  96     if (arg2) {
  97         if (arg2->type != t_bool) {
  98             cfgfatal(arg2->loc,"randomsource",
  99                      "blocking parameter (arg2) must be bool\n");
 100         }
 101         st->ops.blocking=arg2->data.bool;
 102     }
 103
 104     if (!filename) {
 105         cfgfatal(loc,"randomsource","requires a filename\n");
 106     }
 107     st->fd=open(filename,O_RDONLY);
 108     if (st->fd<0) {
 109         fatal_perror("randomsource (%s:%d): cannot open %s",arg1->loc.file,
 110                      arg1->loc.line,filename);
 111     }
 112     return new_closure(&st->cl);
 113 }
 114
 115 void random_module(dict_t *d)
 116 {
 117     add_closure(d,"randomfile",random_apply);
 118 }