sbin/dhclient/privsep.c

   1 /*      $OpenBSD: privsep.c,v 1.7 2004/05/10 18:34:42 deraadt 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 <sys/cdefs.h>
  20 __FBSDID("$FreeBSD$");
  21
  22 #include "dhcpd.h"
  23 #include "privsep.h"
  24
  25 struct buf *
  26 buf_open(size_t len)
  27 {
  28         struct buf      *buf;
  29
  30         if ((buf = calloc(1, sizeof(struct buf))) == NULL)
  31                 return (NULL);
  32         if ((buf->buf = malloc(len)) == NULL) {
  33                 free(buf);
  34                 return (NULL);
  35         }
  36         buf->size = len;
  37
  38         return (buf);
  39 }
  40
  41 int
  42 buf_add(struct buf *buf, void *data, size_t len)
  43 {
  44         if (buf->wpos + len > buf->size)
  45                 return (-1);
  46
  47         memcpy(buf->buf + buf->wpos, data, len);
  48         buf->wpos += len;
  49         return (0);
  50 }
  51
  52 int
  53 buf_close(int sock, struct buf *buf)
  54 {
  55         ssize_t n;
  56
  57         do {
  58                 n = write(sock, buf->buf + buf->rpos, buf->size - buf->rpos);
  59                 if (n != -1)
  60                         buf->rpos += n;
  61                 if (n == 0) {                   /* connection closed */
  62                         errno = 0;
  63                         return (-1);
  64                 }
  65         } while (n == -1 && (errno == EAGAIN || errno == EINTR));
  66
  67         if (buf->rpos < buf->size)
  68                 error("short write: wanted %lu got %ld bytes",
  69                     (unsigned long)buf->size, (long)buf->rpos);
  70
  71         free(buf->buf);
  72         free(buf);
  73         return (n);
  74 }
  75
  76 ssize_t
  77 buf_read(int sock, void *buf, size_t nbytes)
  78 {
  79         ssize_t n, r = 0;
  80         char *p = buf;
  81
  82         do {
  83                 n = read(sock, p, nbytes);
  84                 if (n == 0)
  85                         error("connection closed");
  86                 if (n != -1) {
  87                         r += n;
  88                         p += n;
  89                         nbytes -= n;
  90                 }
  91         } while (n == -1 && (errno == EINTR || errno == EAGAIN));
  92
  93         if (n == -1)
  94                 error("buf_read: %m");
  95
  96         if (r < nbytes)
  97                 error("short read: wanted %lu got %ld bytes",
  98                     (unsigned long)nbytes, (long)r);
  99
 100         return (r);
 101 }
 102
 103 void
 104 dispatch_imsg(struct interface_info *ifi, int fd)
 105 {
 106         struct imsg_hdr          hdr;
 107         char                    *medium, *reason, *filename,
 108                                 *servername, *prefix;
 109         size_t                   medium_len, reason_len, filename_len,
 110                                  servername_len, prefix_len, totlen;
 111         struct client_lease      lease;
 112         int                      ret, i, optlen;
 113         struct buf              *buf;
 114         u_int16_t               mtu;
 115
 116         buf_read(fd, &hdr, sizeof(hdr));
 117
 118         switch (hdr.code) {
 119         case IMSG_SCRIPT_INIT:
 120                 if (hdr.len < sizeof(hdr) + sizeof(size_t))
 121                         error("corrupted message received");
 122                 buf_read(fd, &medium_len, sizeof(medium_len));
 123                 if (hdr.len < medium_len + sizeof(size_t) + sizeof(hdr)
 124                     + sizeof(size_t) || medium_len == SIZE_T_MAX)
 125                         error("corrupted message received");
 126                 if (medium_len > 0) {
 127                         if ((medium = calloc(1, medium_len + 1)) == NULL)
 128                                 error("%m");
 129                         buf_read(fd, medium, medium_len);
 130                 } else
 131                         medium = NULL;
 132
 133                 buf_read(fd, &reason_len, sizeof(reason_len));
 134                 if (hdr.len < medium_len + reason_len + sizeof(hdr) ||
 135                     reason_len == SIZE_T_MAX)
 136                         error("corrupted message received");
 137                 if (reason_len > 0) {
 138                         if ((reason = calloc(1, reason_len + 1)) == NULL)
 139                                 error("%m");
 140                         buf_read(fd, reason, reason_len);
 141                 } else
 142                         reason = NULL;
 143
 144                 priv_script_init(reason, medium);
 145                 free(reason);
 146                 free(medium);
 147                 break;
 148         case IMSG_SCRIPT_WRITE_PARAMS:
 149                 bzero(&lease, sizeof lease);
 150                 totlen = sizeof(hdr) + sizeof(lease) + sizeof(size_t);
 151                 if (hdr.len < totlen)
 152                         error("corrupted message received");
 153                 buf_read(fd, &lease, sizeof(lease));
 154
 155                 buf_read(fd, &filename_len, sizeof(filename_len));
 156                 totlen += filename_len + sizeof(size_t);
 157                 if (hdr.len < totlen || filename_len == SIZE_T_MAX)
 158                         error("corrupted message received");
 159                 if (filename_len > 0) {
 160                         if ((filename = calloc(1, filename_len + 1)) == NULL)
 161                                 error("%m");
 162                         buf_read(fd, filename, filename_len);
 163                 } else
 164                         filename = NULL;
 165
 166                 buf_read(fd, &servername_len, sizeof(servername_len));
 167                 totlen += servername_len + sizeof(size_t);
 168                 if (hdr.len < totlen || servername_len == SIZE_T_MAX)
 169                         error("corrupted message received");
 170                 if (servername_len > 0) {
 171                         if ((servername =
 172                             calloc(1, servername_len + 1)) == NULL)
 173                                 error("%m");
 174                         buf_read(fd, servername, servername_len);
 175                 } else
 176                         servername = NULL;
 177
 178                 buf_read(fd, &prefix_len, sizeof(prefix_len));
 179                 totlen += prefix_len;
 180                 if (hdr.len < totlen || prefix_len == SIZE_T_MAX)
 181                         error("corrupted message received");
 182                 if (prefix_len > 0) {
 183                         if ((prefix = calloc(1, prefix_len + 1)) == NULL)
 184                                 error("%m");
 185                         buf_read(fd, prefix, prefix_len);
 186                 } else
 187                         prefix = NULL;
 188
 189                 for (i = 0; i < 256; i++) {
 190                         totlen += sizeof(optlen);
 191                         if (hdr.len < totlen)
 192                                 error("corrupted message received");
 193                         buf_read(fd, &optlen, sizeof(optlen));
 194                         lease.options[i].data = NULL;
 195                         lease.options[i].len = optlen;
 196                         if (optlen > 0) {
 197                                 totlen += optlen;
 198                                 if (hdr.len < totlen || optlen == SIZE_T_MAX)
 199                                         error("corrupted message received");
 200                                 lease.options[i].data =
 201                                     calloc(1, optlen + 1);
 202                                 if (lease.options[i].data == NULL)
 203                                     error("%m");
 204                                 buf_read(fd, lease.options[i].data, optlen);
 205                         }
 206                 }
 207                 lease.server_name = servername;
 208                 lease.filename = filename;
 209
 210                 priv_script_write_params(prefix, &lease);
 211
 212                 free(servername);
 213                 free(filename);
 214                 free(prefix);
 215                 for (i = 0; i < 256; i++)
 216                         if (lease.options[i].len > 0)
 217                                 free(lease.options[i].data);
 218                 break;
 219         case IMSG_SCRIPT_GO:
 220                 if (hdr.len != sizeof(hdr))
 221                         error("corrupted message received");
 222
 223                 ret = priv_script_go();
 224
 225                 hdr.code = IMSG_SCRIPT_GO_RET;
 226                 hdr.len = sizeof(struct imsg_hdr) + sizeof(int);
 227                 if ((buf = buf_open(hdr.len)) == NULL)
 228                         error("buf_open: %m");
 229                 if (buf_add(buf, &hdr, sizeof(hdr)))
 230                         error("buf_add: %m");
 231                 if (buf_add(buf, &ret, sizeof(ret)))
 232                         error("buf_add: %m");
 233                 if (buf_close(fd, buf) == -1)
 234                         error("buf_close: %m");
 235                 break;
 236         case IMSG_SEND_PACKET:
 237                 send_packet_priv(ifi, &hdr, fd);
 238                 break;
 239         case IMSG_SET_INTERFACE_MTU:
 240                 if (hdr.len < sizeof(hdr) + sizeof(u_int16_t))
 241                         error("corrupted message received");
 242
 243                 buf_read(fd, &mtu, sizeof(u_int16_t));
 244                 interface_set_mtu_priv(ifi->name, mtu);
 245                 break;
 246         default:
 247                 error("received unknown message, code %d", hdr.code);
 248         }
 249 }