iter_scrub.c File Reference

#include "config.h"
#include "iterator/iter_scrub.h"
#include "iterator/iterator.h"
#include "iterator/iter_priv.h"
#include "services/cache/rrset.h"
#include "util/log.h"
#include "util/net_help.h"
#include "util/regional.h"
#include "util/config_file.h"
#include "util/module.h"
#include "util/data/msgparse.h"
#include "util/data/dname.h"
#include "util/data/msgreply.h"
#include "util/alloc.h"
#include "sldns/sbuffer.h"

Macros
#define	RRSET_SCRUB_OK   0x80
	RRset flag used during scrubbing. More...

Functions
static void	remove_rrset (const char *str, sldns_buffer *pkt, struct msg_parse *msg, struct rrset_parse *prev, struct rrset_parse **rrset)
	remove rrset, update loop variables
static int	has_additional (uint16_t t)
	return true if rr type has additional names in it
static int	get_additional_name (struct rrset_parse *rrset, struct rr_parse *rr, uint8_t **nm, size_t *nmlen, sldns_buffer *pkt)
	get additional name from rrset RR, return false if no name present
static void	mark_additional_rrset (sldns_buffer *pkt, struct msg_parse *msg, struct rrset_parse *rrset)
	Place mark on rrsets in additional section they are OK.
static int	parse_get_cname_target (struct rrset_parse *rrset, uint8_t **sname, size_t *snamelen, sldns_buffer *pkt)
	Get target name of a CNAME.
static int	synth_cname (uint8_t *qname, size_t qnamelen, struct rrset_parse *dname_rrset, uint8_t *alias, size_t *aliaslen, sldns_buffer *pkt)
	Synthesize CNAME from DNAME, false if too long.
static struct rrset_parse *	synth_cname_rrset (uint8_t **sname, size_t *snamelen, uint8_t *alias, size_t aliaslen, struct regional *region, struct msg_parse *msg, struct rrset_parse *rrset, struct rrset_parse *prev, struct rrset_parse *nx, sldns_buffer *pkt)
	synthesize a CNAME rrset
static int	pkt_strict_sub (sldns_buffer *pkt, uint8_t *sname, uint8_t *dr)
	check if DNAME applies to a name
static int	pkt_sub (sldns_buffer *pkt, uint8_t *comprname, uint8_t *zone)
	check subdomain with decompression
static int	sub_of_pkt (sldns_buffer *pkt, uint8_t *zone, uint8_t *comprname)
	check subdomain with decompression, compressed is parent
static int	soa_in_auth (struct msg_parse *msg)
	Check if there are SOA records in the authority section (negative)
static int	scrub_normalize (sldns_buffer *pkt, struct msg_parse *msg, struct query_info *qinfo, struct regional *region)
	This routine normalizes a response. More...
static void	store_rrset (sldns_buffer *pkt, struct msg_parse *msg, struct module_env *env, struct rrset_parse *rrset)
	Store potential poison in the cache (only if hardening disabled). More...
static int	sanitize_nsec_is_overreach (sldns_buffer *pkt, struct rrset_parse *rrset, uint8_t *zonename)
	Check if right hand name in NSEC is within zone. More...
static int	scrub_sanitize (sldns_buffer *pkt, struct msg_parse *msg, struct query_info *qinfo, uint8_t *zonename, struct module_env *env, struct iter_env *ie)
	Given a response event, remove suspect RRsets from the response. More...
int	scrub_message (sldns_buffer *pkt, struct msg_parse *msg, struct query_info *qinfo, uint8_t *zonename, struct regional *region, struct module_env *env, struct iter_env *ie)
	Cleanup the passed dns message. More...

Detailed Description

This file has routine(s) for cleaning up incoming DNS messages from possible useless or malicious junk in it.

Macro Definition Documentation

RRSET_SCRUB_OK

#define RRSET_SCRUB_OK   0x80

RRset flag used during scrubbing.

The RRset is OK.

Function Documentation

scrub_normalize()

static int scrub_normalize ( sldns_buffer *  pkt, struct msg_parse *  msg, struct query_info *  qinfo, struct regional *  region  )

static

This routine normalizes a response.

This includes removing "irrelevant" records from the answer and additional sections and (re)synthesizing CNAMEs from DNAMEs, if present.

Parameters

pkt	packet.
msg	msg to normalize.
qinfo	original query.
region	where to allocate synthesized CNAMEs.

Returns

0 on error.

References msg_parse::flags, FLAGS_GET_RCODE, query_info::qname, and query_info::qname_len.

store_rrset()

static void store_rrset ( sldns_buffer *  pkt, struct msg_parse *  msg, struct module_env *  env, struct rrset_parse *  rrset  )

static

Store potential poison in the cache (only if hardening disabled).

The rrset is stored in the cache but removed from the message. So that it will be used for infrastructure purposes, but not be returned to the client.

Parameters

pkt	packet
msg	message parsed
env	environment with cache
rrset	to store.

References module_env::alloc, alloc_special_obtain(), alloc_special_release(), lruhash_entry::data, ub_packed_rrset_key::entry, rrset_ref::id, ub_packed_rrset_key::id, rrset_ref::key, module_env::now, packed_rrset_ttl_add(), parse_copy_decompress_rrset(), module_env::rrset_cache, and rrset_cache_update().

sanitize_nsec_is_overreach()

static int sanitize_nsec_is_overreach ( sldns_buffer *  pkt, struct rrset_parse *  rrset, uint8_t *  zonename  )

static

Check if right hand name in NSEC is within zone.

Parameters

pkt	the packet buffer for decompression.
rrset	the NSEC rrset
zonename	the zone name.

Returns

true if BAD.

References log_assert, and rrset_parse::type.

scrub_sanitize()

static int scrub_sanitize ( sldns_buffer *  pkt, struct msg_parse *  msg, struct query_info *  qinfo, uint8_t *  zonename, struct module_env *  env, struct iter_env *  ie  )

static

Given a response event, remove suspect RRsets from the response.

"Suspect" rrsets are potentially poison. Note that this routine expects the response to be in a "normalized" state – that is, all "irrelevant" RRsets have already been removed, CNAMEs are in order, etc.

Parameters

pkt	packet.
msg	msg to normalize.
qinfo	the question originally asked.
zonename	name of server zone.
env	module environment with config and cache.
ie	iterator environment with private address data.

Returns

0 on error.

References LDNS_RR_TYPE_DNAME, msg_parse::rrset_first, rrset_parse::section, and rrset_parse::type.

scrub_message()

int scrub_message	(	struct sldns_buffer *	pkt,
		struct msg_parse *	msg,
		struct query_info *	qinfo,
		uint8_t *	zonename,
		struct regional *	regional,
		struct module_env *	env,
		struct iter_env *	ie
	)

Cleanup the passed dns message.

Parameters

pkt	the packet itself, for resolving name compression pointers. the packet buffer is unaltered.
msg	the parsed packet, this structure is cleaned up.
qinfo	the query info that was sent to the server. Checked.
zonename	the name of the last delegation point. Used to determine out of bailiwick information.
regional	where to allocate (new) parts of the message.
env	module environment with config settings and cache.
ie	iterator module environment data.

Returns

: false if the message is total waste. true if scrubbed with success.

References BIT_AD, BIT_QR, BIT_Z, msg_parse::flags, FLAGS_GET_RCODE, LDNS_RR_TYPE_NS, log_nametypeclass(), query_info::qclass, msg_parse::qdcount, and VERB_ALGO.