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udhcpc: sanitize hostnames in incoming packets. Closes 3979.

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The following options are replaced with string "bad" if they
contain malformed hostname:
HOST_NAME, DOMAIN_NAME, NIS_DOMAIN, TFTP_SERVER_NAME

function                                             old     new   delta
xmalloc_optname_optval                               850     888     +38
attach_option                                        440     443      +3
len_of_option_as_string                               13      14      +1
dhcp_option_lengths                                   13      14      +1
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/0 up/down: 43/0)               Total: 43 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
2011-12-08 16:41:05 +01:00
parent 53782d9221
commit 7280d2017d
3 changed files with 73 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
networking/udhcp/common.c
View File

@@ -29,9 +29,9 @@ const struct dhcp_optflag dhcp_optflags[] = {
// { OPTION_IP | OPTION_LIST , 0x07 }, /* DHCP_LOG_SERVER */
// { OPTION_IP | OPTION_LIST , 0x08 }, /* DHCP_COOKIE_SERVER */
{ OPTION_IP | OPTION_LIST , 0x09 }, /* DHCP_LPR_SERVER */
{ OPTION_STRING | OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME */
{ OPTION_STRING_HOST | OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME */
{ OPTION_U16 , 0x0d }, /* DHCP_BOOT_SIZE */
{ OPTION_STRING | OPTION_REQ, 0x0f }, /* DHCP_DOMAIN_NAME */
{ OPTION_STRING_HOST | OPTION_REQ, 0x0f }, /* DHCP_DOMAIN_NAME */
{ OPTION_IP , 0x10 }, /* DHCP_SWAP_SERVER */
{ OPTION_STRING , 0x11 }, /* DHCP_ROOT_PATH */
{ OPTION_U8 , 0x17 }, /* DHCP_IP_TTL */
@@ -41,7 +41,7 @@ const struct dhcp_optflag dhcp_optflags[] = {
//server would let us know anyway?
{ OPTION_IP | OPTION_REQ, 0x1c }, /* DHCP_BROADCAST */
{ OPTION_IP_PAIR | OPTION_LIST , 0x21 }, /* DHCP_ROUTES */
{ OPTION_STRING , 0x28 }, /* DHCP_NIS_DOMAIN */
{ OPTION_STRING_HOST , 0x28 }, /* DHCP_NIS_DOMAIN */
{ OPTION_IP | OPTION_LIST , 0x29 }, /* DHCP_NIS_SERVER */
{ OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2a }, /* DHCP_NTP_SERVER */
{ OPTION_IP | OPTION_LIST , 0x2c }, /* DHCP_WINS_SERVER */
@@ -49,7 +49,7 @@ const struct dhcp_optflag dhcp_optflags[] = {
{ OPTION_IP , 0x36 }, /* DHCP_SERVER_ID */
{ OPTION_STRING , 0x38 }, /* DHCP_ERR_MESSAGE */
//TODO: must be combined with 'sname' and 'file' handling:
{ OPTION_STRING , 0x42 }, /* DHCP_TFTP_SERVER_NAME */
{ OPTION_STRING_HOST , 0x42 }, /* DHCP_TFTP_SERVER_NAME */
{ OPTION_STRING , 0x43 }, /* DHCP_BOOT_FILE */
//TODO: not a string, but a set of LASCII strings:
// { OPTION_STRING , 0x4D }, /* DHCP_USER_CLASS */
@@ -148,6 +148,7 @@ const uint8_t dhcp_option_lengths[] ALIGN1 = {
[OPTION_IP_PAIR] = 8,
// [OPTION_BOOLEAN] = 1,
[OPTION_STRING] = 1, /* ignored by udhcp_str2optset */
[OPTION_STRING_HOST] = 1, /* ignored by udhcp_str2optset */
#if ENABLE_FEATURE_UDHCP_RFC3397
[OPTION_DNS_STRING] = 1, /* ignored by both udhcp_str2optset and xmalloc_optname_optval */
[OPTION_SIP_SERVERS] = 1,
@@ -417,7 +418,9 @@ static NOINLINE void attach_option(
/* actually 255 is ok too, but adding a space can overlow it */
existing->data = xrealloc(existing->data, OPT_DATA + 1 + old_len + length);
if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING) {
if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING
|| (optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING_HOST
) {
/* add space separator between STRING options in a list */
existing->data[OPT_DATA + old_len] = ' ';
old_len++;
@@ -481,6 +484,7 @@ int FAST_FUNC udhcp_str2optset(const char *const_str, void *arg)
retval = udhcp_str2nip(val, buffer + 4);
break;
case OPTION_STRING:
case OPTION_STRING_HOST:
#if ENABLE_FEATURE_UDHCP_RFC3397
case OPTION_DNS_STRING:
#endif