sbin/dhclient/privsep.c

   1 /*      $OpenBSD: src/sbin/dhclient/privsep.c,v 1.16 2011/04/04 11:14:52 krw Exp $      */
   2
   3 /*
   4  * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER IN
  15  * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  16  * OF OR IN CONNECTION WITH THE USE, ABUSE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #include "dhcpd.h"
  20 #include "privsep.h"
  21
  22 struct buf *
  23 buf_open(size_t len)
  24 {
  25         struct buf      *buf;
  26
  27         if ((buf = calloc(1, sizeof(struct buf))) == NULL)
  28                 error("buf_open: %m");
  29         if ((buf->buf = malloc(len)) == NULL) {
  30                 free(buf);
  31                 error("buf_open: %m");
  32         }
  33         buf->size = len;
  34
  35         return (buf);
  36 }
  37
  38 void
  39 buf_add(struct buf *buf, void *data, size_t len)
  40 {
  41         if (len == 0)
  42                 return;
  43
  44         if (buf->wpos + len > buf->size)
  45                 error("buf_add: %m");
  46
  47         memcpy(buf->buf + buf->wpos, data, len);
  48         buf->wpos += len;
  49 }
  50
  51 void
  52 buf_close(int sock, struct buf *buf)
  53 {
  54         ssize_t n;
  55
  56         do {
  57                 n = write(sock, buf->buf + buf->rpos, buf->size - buf->rpos);
  58                 if (n == 0)                     /* connection closed */
  59                         error("buf_close (connection closed)");
  60                 if (n != -1 && n < buf->size - buf->rpos)
  61                         error("buf_close (short write): %m");
  62
  63         } while (n == -1 && (errno == EAGAIN || errno == EINTR));
  64
  65         if (n == -1)
  66                 error("buf_close: %m");
  67
  68         free(buf->buf);
  69         free(buf);
  70 }
  71
  72 void
  73 buf_read(int sock, void *buf, size_t nbytes)
  74 {
  75         ssize_t n;
  76
  77         do {
  78                 n = read(sock, buf, nbytes);
  79                 if (n == 0) {                   /* connection closed */
  80 #ifdef DEBUG
  81                         debug("buf_read (connection closed)");
  82 #endif
  83                         exit(1);
  84                 }
  85                 if (n != -1 && n < nbytes)
  86                         error("buf_read (short read): %m");
  87         } while (n == -1 && (errno == EINTR || errno == EAGAIN));
  88
  89         if (n == -1)
  90                 error("buf_read: %m");
  91 }
  92
  93 void
  94 dispatch_imsg(int fd)
  95 {
  96         struct imsg_hdr          hdr;
  97         char                    *reason, *filename,
  98                                 *servername, *prefix;
  99         size_t                   reason_len, filename_len,
 100                                  servername_len, prefix_len, totlen;
 101         struct client_lease      lease;
 102         int                      ret, i, optlen;
 103         struct buf              *buf;
 104
 105         buf_read(fd, &hdr, sizeof(hdr));
 106
 107         switch (hdr.code) {
 108         case IMSG_SCRIPT_INIT:
 109                 if (hdr.len < sizeof(hdr) + sizeof(size_t))
 110                         error("corrupted message received");
 111                 buf_read(fd, &reason_len, sizeof(reason_len));
 112                 if (hdr.len < reason_len + sizeof(hdr) + sizeof(size_t) ||
 113                     reason_len == SIZE_T_MAX)
 114                         error("corrupted message received");
 115                 if (reason_len > 0) {
 116                         if ((reason = calloc(1, reason_len + 1)) == NULL)
 117                                 error("%m");
 118                         buf_read(fd, reason, reason_len);
 119                 } else
 120                         reason = NULL;
 121
 122                 priv_script_init(reason);
 123                 free(reason);
 124                 break;
 125         case IMSG_SCRIPT_WRITE_PARAMS:
 126                 bzero(&lease, sizeof lease);
 127                 totlen = sizeof(hdr) + sizeof(lease) + sizeof(size_t);
 128                 if (hdr.len < totlen)
 129                         error("corrupted message received");
 130                 buf_read(fd, &lease, sizeof(lease));
 131
 132                 buf_read(fd, &filename_len, sizeof(filename_len));
 133                 totlen += filename_len + sizeof(size_t);
 134                 if (hdr.len < totlen || filename_len == SIZE_T_MAX)
 135                         error("corrupted message received");
 136                 if (filename_len > 0) {
 137                         if ((filename = calloc(1, filename_len + 1)) == NULL)
 138                                 error("%m");
 139                         buf_read(fd, filename, filename_len);
 140                 } else
 141                         filename = NULL;
 142
 143                 buf_read(fd, &servername_len, sizeof(servername_len));
 144                 totlen += servername_len + sizeof(size_t);
 145                 if (hdr.len < totlen || servername_len == SIZE_T_MAX)
 146                         error("corrupted message received");
 147                 if (servername_len > 0) {
 148                         if ((servername =
 149                             calloc(1, servername_len + 1)) == NULL)
 150                                 error("%m");
 151                         buf_read(fd, servername, servername_len);
 152                 } else
 153                         servername = NULL;
 154
 155                 buf_read(fd, &prefix_len, sizeof(prefix_len));
 156                 totlen += prefix_len;
 157                 if (hdr.len < totlen || prefix_len == SIZE_T_MAX)
 158                         error("corrupted message received");
 159                 if (prefix_len > 0) {
 160                         if ((prefix = calloc(1, prefix_len + 1)) == NULL)
 161                                 error("%m");
 162                         buf_read(fd, prefix, prefix_len);
 163                 } else
 164                         prefix = NULL;
 165
 166                 for (i = 0; i < 256; i++) {
 167                         totlen += sizeof(optlen);
 168                         if (hdr.len < totlen)
 169                                 error("corrupted message received");
 170                         buf_read(fd, &optlen, sizeof(optlen));
 171                         lease.options[i].data = NULL;
 172                         lease.options[i].len = optlen;
 173                         if (optlen > 0) {
 174                                 totlen += optlen;
 175                                 if (hdr.len < totlen || optlen == SIZE_T_MAX)
 176                                         error("corrupted message received");
 177                                 lease.options[i].data =
 178                                     calloc(1, optlen + 1);
 179                                 if (lease.options[i].data == NULL)
 180                                     error("%m");
 181                                 buf_read(fd, lease.options[i].data, optlen);
 182                         }
 183                 }
 184                 lease.server_name = servername;
 185                 lease.filename = filename;
 186
 187                 priv_script_write_params(prefix, &lease);
 188
 189                 free(servername);
 190                 free(filename);
 191                 free(prefix);
 192                 for (i = 0; i < 256; i++)
 193                         if (lease.options[i].len > 0)
 194                                 free(lease.options[i].data);
 195                 break;
 196         case IMSG_SCRIPT_GO:
 197                 if (hdr.len != sizeof(hdr))
 198                         error("corrupted message received");
 199
 200                 ret = priv_script_go();
 201
 202                 hdr.code = IMSG_SCRIPT_GO_RET;
 203                 hdr.len = sizeof(struct imsg_hdr) + sizeof(int);
 204                 if ((buf = buf_open(hdr.len)) == NULL)
 205                         error("buf_open: %m");
 206                 buf_add(buf, &hdr, sizeof(hdr));
 207                 buf_add(buf, &ret, sizeof(ret));
 208                 buf_close(fd, buf);
 209                 break;
 210         default:
 211                 error("received unknown message, code %d", hdr.code);
 212         }
 213 }