#include "iterator/iter_scrub.h"
#include "util/log.h"
#include "util/net_help.h"
+#include "util/region-allocator.h"
#include "util/data/msgparse.h"
#include "util/data/dname.h"
#include "util/data/msgreply.h"
+/** RRset flag used during scrubbing. The RRset is OK. */
+#define RRSET_SCRUB_OK 0x80
+
+/** remove rrset, update loop variables */
+static void
+remove_rrset(const char* str, ldns_buffer* pkt, struct msg_parse* msg,
+ struct rrset_parse* prev, struct rrset_parse** rrset)
+{
+ if(verbosity >= VERB_ALGO
+ && (*rrset)->dname_len <= LDNS_MAX_DOMAINLEN) {
+ uint8_t buf[LDNS_MAX_DOMAINLEN+1];
+ dname_pkt_copy(pkt, buf, (*rrset)->dname);
+ log_nametypeclass(str, buf,
+ (*rrset)->type, ntohs((*rrset)->rrset_class));
+ }
+ if(prev)
+ prev->rrset_all_next = (*rrset)->rrset_all_next;
+ else msg->rrset_first = (*rrset)->rrset_all_next;
+ if(msg->rrset_last == *rrset)
+ msg->rrset_last = prev;
+ msg->rrset_count --;
+ switch((*rrset)->section) {
+ case LDNS_SECTION_ANSWER: msg->an_rrsets--; break;
+ case LDNS_SECTION_AUTHORITY: msg->ns_rrsets--; break;
+ case LDNS_SECTION_ADDITIONAL: msg->ar_rrsets--; break;
+ default: log_assert(0);
+ }
+ msgparse_bucket_remove(msg, *rrset);
+ *rrset = (*rrset)->rrset_all_next;
+}
+
+/** return true if rr type has additional names in it */
+static int
+has_additional(uint16_t t)
+{
+ switch(t) {
+ case LDNS_RR_TYPE_MB:
+ case LDNS_RR_TYPE_MD:
+ case LDNS_RR_TYPE_MF:
+ case LDNS_RR_TYPE_NS:
+ case LDNS_RR_TYPE_MX:
+ case LDNS_RR_TYPE_KX:
+ case LDNS_RR_TYPE_SRV:
+ return 1;
+ case LDNS_RR_TYPE_NAPTR:
+ /* TODO: NAPTR not supported, glue stripped off */
+ return 0;
+ default:
+ return 0;
+ }
+ return 0;
+}
+
+/** get additional name from rrset RR, return false if no name present */
+static int
+get_additional_name(struct rrset_parse* rrset, struct rr_parse* rr,
+ uint8_t** nm, size_t* nmlen, ldns_buffer* pkt)
+{
+ size_t offset = 0;
+ size_t len, oldpos;
+ switch(rrset->type) {
+ case LDNS_RR_TYPE_MB:
+ case LDNS_RR_TYPE_MD:
+ case LDNS_RR_TYPE_MF:
+ case LDNS_RR_TYPE_NS:
+ offset = 0;
+ break;
+ case LDNS_RR_TYPE_MX:
+ case LDNS_RR_TYPE_KX:
+ offset = 2;
+ break;
+ case LDNS_RR_TYPE_SRV:
+ offset = 6;
+ break;
+ case LDNS_RR_TYPE_NAPTR:
+ /* TODO: NAPTR not supported, glue stripped off */
+ return 0;
+ default:
+ return 0;
+ }
+ len = ldns_read_uint16(rr->ttl_data+sizeof(uint32_t));
+ if(len < offset+1)
+ return 0; /* rdata field too small */
+ *nm = rr->ttl_data+sizeof(uint32_t)+sizeof(uint16_t)+offset;
+ oldpos = ldns_buffer_position(pkt);
+ ldns_buffer_set_position(pkt, (size_t)(*nm - ldns_buffer_begin(pkt)));
+ *nmlen = pkt_dname_len(pkt);
+ ldns_buffer_set_position(pkt, oldpos);
+ if(*nmlen == 0)
+ return 0;
+ return 1;
+}
+
+/** Place mark on rrsets in additional section they are OK */
+static void
+mark_additional_rrset(ldns_buffer* pkt, struct msg_parse* msg,
+ struct rrset_parse* rrset)
+{
+ /* Mark A and AAAA for NS as appropriate additional section info. */
+ uint8_t* nm = NULL;
+ size_t nmlen = 0;
+ struct rr_parse* rr;
+
+ if(!has_additional(rrset->type))
+ return;
+ for(rr = rrset->rr_first; rr; rr = rr->next) {
+ if(get_additional_name(rrset, rr, &nm, &nmlen, pkt)) {
+ /* mark A */
+ hashvalue_t h = pkt_hash_rrset(pkt, nm, LDNS_RR_TYPE_A,
+ rrset->rrset_class, 0);
+ struct rrset_parse* r = msgparse_hashtable_lookup(
+ msg, pkt, h, 0, nm, nmlen,
+ LDNS_RR_TYPE_A, rrset->rrset_class);
+ if(r && r->section == LDNS_SECTION_ADDITIONAL) {
+ r->flags |= RRSET_SCRUB_OK;
+ }
+
+ /* mark AAAA */
+ h = pkt_hash_rrset(pkt, nm, LDNS_RR_TYPE_AAAA,
+ rrset->rrset_class, 0);
+ r = msgparse_hashtable_lookup(msg, pkt, h, 0, nm,
+ nmlen, LDNS_RR_TYPE_AAAA, rrset->rrset_class);
+ if(r && r->section == LDNS_SECTION_ADDITIONAL) {
+ r->flags |= RRSET_SCRUB_OK;
+ }
+ }
+ }
+}
+
+/** Get target name of a CNAME */
+static int
+parse_get_cname_target(struct rrset_parse* rrset, uint8_t** sname,
+ size_t* snamelen)
+{
+ if(rrset->rr_count != 1) {
+ verbose(VERB_ALGO, "Found CNAME rrset with "
+ "size > 1: %d", rrset->rr_count);
+ return 0;
+ }
+ if(rrset->rr_first->size < sizeof(uint16_t)+1)
+ return 0; /* CNAME rdata too small */
+ *sname = rrset->rr_first->ttl_data + sizeof(uint32_t)
+ + sizeof(uint16_t); /* skip ttl, rdatalen */
+ *snamelen = rrset->rr_first->size - sizeof(uint16_t);
+ return 1;
+}
+
+/** Synthesize CNAME from DNAME, false if too long */
+static int
+synth_cname(uint8_t* qname, size_t qnamelen, struct rrset_parse* dname_rrset,
+ uint8_t* alias, size_t* aliaslen, ldns_buffer* pkt)
+{
+ /* we already know that sname is a strict subdomain of DNAME owner */
+ uint8_t* dtarg = NULL;
+ size_t dtarglen;
+ if(!parse_get_cname_target(dname_rrset, &dtarg, &dtarglen))
+ return 0;
+ log_assert(qnamelen > dname_rrset->dname_len);
+ /* DNAME from com. to net. with qname example.com. -> example.net. */
+ /* so: \3com\0 to \3net\0 and qname \7example\3com\0 */
+ *aliaslen = qnamelen + dtarglen - dname_rrset->dname_len;
+ if(*aliaslen > LDNS_MAX_DOMAINLEN)
+ return 0; /* should have been RCODE YXDOMAIN */
+ /* decompress dnames into buffer, we know it fits */
+ dname_pkt_copy(pkt, alias, qname);
+ dname_pkt_copy(pkt, alias+(qnamelen-dname_rrset->dname_len), dtarg);
+ return 1;
+}
+
+/** synthesize a CNAME rrset */
+static struct rrset_parse*
+synth_cname_rrset(uint8_t** sname, size_t* snamelen, uint8_t* alias,
+ size_t aliaslen, struct region* region, struct msg_parse* msg,
+ struct rrset_parse* rrset, struct rrset_parse* prev,
+ struct rrset_parse* nx, ldns_buffer* pkt)
+{
+ struct rrset_parse* cn = (struct rrset_parse*)region_alloc(region,
+ sizeof(struct rrset_parse));
+ if(!cn)
+ return NULL;
+ memset(cn, 0, sizeof(*cn));
+ cn->rr_first = (struct rr_parse*)region_alloc(region,
+ sizeof(struct rr_parse));
+ if(!cn->rr_first)
+ return NULL;
+ cn->rr_last = cn->rr_first;
+ /* CNAME from sname to alias */
+ cn->dname = (uint8_t*)region_alloc_init(region, *sname, *snamelen);
+ cn->dname_len = *snamelen;
+ cn->type = LDNS_RR_TYPE_CNAME;
+ cn->section = rrset->section;
+ cn->rrset_class = rrset->rrset_class;
+ cn->rr_count = 1;
+ cn->size = sizeof(uint16_t) + aliaslen;
+ cn->hash=pkt_hash_rrset(pkt, cn->dname, cn->type, cn->rrset_class, 0);
+ /* allocate TTL + rdatalen + uncompressed dname */
+ memset(cn->rr_first, 0, sizeof(struct rr_parse));
+ cn->rr_first->ttl_data = (uint8_t*)region_alloc(region,
+ sizeof(uint32_t)+sizeof(uint16_t)+aliaslen);
+ if(!cn->rr_first->ttl_data)
+ return NULL;
+ ldns_write_uint32(cn->rr_first->ttl_data, 0); /* TTL = 0 */
+ ldns_write_uint16(cn->rr_first->ttl_data+4, aliaslen);
+ memmove(cn->rr_first->ttl_data+6, alias, aliaslen);
+ cn->rr_first->size = sizeof(uint16_t)+aliaslen;
+
+ /* link it in */
+ cn->rrset_all_next = nx;
+ if(prev)
+ prev->rrset_all_next = cn;
+ else msg->rrset_first = cn;
+ if(nx == NULL)
+ msg->rrset_last = cn;
+ msg->rrset_count ++;
+ msg->an_rrsets++;
+ /* it is not inserted in the msg hashtable. */
+
+ *sname = cn->rr_first->ttl_data + sizeof(uint32_t)+sizeof(uint16_t);
+ *snamelen = aliaslen;
+ return cn;
+}
+
+/** check if DNAME applies to a name */
+static int
+pkt_strict_sub(ldns_buffer* pkt, uint8_t* sname, uint8_t* dr)
+{
+ uint8_t buf[LDNS_MAX_DOMAINLEN+1];
+ /* decompress DNAME name */
+ dname_pkt_copy(pkt, buf, dr);
+ return dname_strict_subdomain_c(sname, buf);
+}
+
+/** check subdomain with decompression */
+static int
+pkt_sub(ldns_buffer* pkt, uint8_t* sname, uint8_t* dr)
+{
+ uint8_t buf[LDNS_MAX_DOMAINLEN+1];
+ /* decompress DNAME name */
+ dname_pkt_copy(pkt, buf, dr);
+ return dname_subdomain_c(sname, buf);
+}
+
/**
* This routine normalizes a response. This includes removing "irrelevant"
* records from the answer and additional sections and (re)synthesizing
{
uint8_t* sname = qinfo->qname;
size_t snamelen = qinfo->qname_len;
- struct rrset_parse* rrset, *prev=NULL;
+ struct rrset_parse* rrset, *prev;
if(FLAGS_GET_RCODE(msg->flags) != LDNS_RCODE_NOERROR &&
FLAGS_GET_RCODE(msg->flags) != LDNS_RCODE_NXDOMAIN)
* synthesized CNAMEs from DNAMEs
* This will strip out-of-order CNAMEs as well. */
- for(rrset = msg->rrset_first; rrset; (prev=rrset),(rrset=rrset->rrset_all_next))
- {
- if(rrset->section != LDNS_SECTION_ANSWER)
- continue;
+ /* walk through the parse packet rrset list, keep track of previous
+ * for insert and delete ease, and examine every RRset */
+ prev = NULL;
+ rrset = msg->rrset_first;
+ while(rrset && rrset->section == LDNS_SECTION_ANSWER) {
if(rrset->type == LDNS_RR_TYPE_DNAME &&
- dname_strict_subdomain_c(sname, rrset->dname)) {
+ pkt_strict_sub(pkt, sname, rrset->dname)) {
+ /* check if next rrset is correct CNAME. else,
+ * synthesize a CNAME */
+ struct rrset_parse* nx = rrset->rrset_all_next;
+ uint8_t alias[LDNS_MAX_DOMAINLEN+1];
+ size_t aliaslen = 0;
if(rrset->rr_count != 1) {
verbose(VERB_ALGO, "Found DNAME rrset with "
"size > 1: %d", rrset->rr_count);
return 0;
}
- /* check if next rrset is correct CNAME. else,
- * synthesize a CNAME */
- /* if nametoolong, return 0 (should been YXDOMAIN) */
+ if(!synth_cname(sname, snamelen, rrset, alias,
+ &aliaslen, pkt)) {
+ verbose(VERB_ALGO, "synthesized CNAME "
+ "too long");
+ return 0;
+ }
+ if(nx && nx->type == LDNS_RR_TYPE_CNAME &&
+ dname_pkt_compare(pkt, sname, nx->dname) == 0) {
+ /* check next cname */
+ uint8_t* t = NULL;
+ size_t tlen = 0;
+ if(!parse_get_cname_target(rrset, &t, &tlen))
+ return 0;
+ if(dname_pkt_compare(pkt, alias, t) == 0) {
+ /* it's OK and better capitalized */
+ prev = rrset;
+ rrset = nx;
+ continue;
+ }
+ /* synth ourselves */
+ }
+ /* synth a CNAME rrset */
+ prev = synth_cname_rrset(&sname, &snamelen, alias,
+ aliaslen, region, msg, rrset, prev, nx, pkt);
+ if(!prev) {
+ log_err("out of memory synthesizing CNAME");
+ return 0;
+ }
+ /* FIXME: resolve the conflict between synthesized
+ * CNAME ttls and the cache. */
+ rrset = nx;
continue;
+
}
/* The only records in the ANSWER section not allowed to */
if(dname_pkt_compare(pkt, sname, rrset->dname) != 0) {
- /* TODO remove_rrset(pkt, msg, prev, rrset); */
+ remove_rrset("normalize: removing irrelevant RRset:",
+ pkt, msg, prev, &rrset);
continue;
}
/* Follow the CNAME chain. */
if(rrset->type == LDNS_RR_TYPE_CNAME) {
- if(rrset->rr_count != 1) {
- verbose(VERB_ALGO, "Found CNAME rrset with "
- "size > 1: %d", rrset->rr_count);
+ if(!parse_get_cname_target(rrset, &sname, &snamelen))
return 0;
- }
- if(rrset->rr_first->size < sizeof(uint16_t)+1)
- return 0; /* CNAME rdata too small */
- sname = rrset->rr_first->ttl_data + sizeof(uint32_t)
- + sizeof(uint16_t); /* skip ttl, rdatalen */
- snamelen = rrset->rr_first->size - sizeof(uint16_t);
+ prev = rrset;
+ rrset = rrset->rrset_all_next;
+ continue;
}
/* Otherwise, make sure that the RRset matches the qtype. */
if(qinfo->qtype != LDNS_RR_TYPE_ANY &&
qinfo->qtype != rrset->type) {
- /*TODO: remove_rrset(); */
+ remove_rrset("normalize: removing irrelevant RRset:",
+ pkt, msg, prev, &rrset);
+ continue;
}
- /* Otherwise, fetch the additional names from the
- * relevant rrset. */
- /* store additional names from rrset rdata */
+ /* Mark the additional names from relevant rrset as OK. */
+ mark_additional_rrset(pkt, msg, rrset);
+
+ prev = rrset;
+ rrset = rrset->rrset_all_next;
}
- /* Get additional names from AUTHORITY */
- /* go through authority section, store add. names from rrdat rdata */
+ /* Mark additional names from AUTHORITY */
+ while(rrset && rrset->section == LDNS_SECTION_AUTHORITY) {
+ mark_additional_rrset(pkt, msg, rrset);
+ prev = rrset;
+ rrset = rrset->rrset_all_next;
+ }
/* For each record in the additional section, remove it if it is an
* address record and not in the collection of additional names
* found in ANSWER and AUTHORITY. */
+ /* These records have not been marked OK previously */
+ while(rrset && rrset->section == LDNS_SECTION_ADDITIONAL) {
+ /* FIXME: what about other types? */
+ if(rrset->type==LDNS_RR_TYPE_A ||
+ rrset->type==LDNS_RR_TYPE_AAAA)
+ {
+ if((rrset->flags & RRSET_SCRUB_OK)) {
+ /* remove flag to clean up flags variable */
+ rrset->flags &= ~RRSET_SCRUB_OK;
+ } else {
+ remove_rrset("normalize: removing irrelevant "
+ "RRset:", pkt, msg, prev, &rrset);
+ continue;
+ }
+ }
+ prev = rrset;
+ rrset = rrset->rrset_all_next;
+ }
- /* FIXME: what about other types? */
+ return 1;
+}
+
+/**
+ * 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.
+ *
+ * @param pkt: packet.
+ * @param msg: msg to normalize.
+ * @param zonename: name of server zone.
+ * @return 0 on error.
+ */
+static int
+scrub_sanitize(ldns_buffer* pkt, struct msg_parse* msg, uint8_t* zonename)
+{
+ struct rrset_parse* rrset, *prev;
+ prev = NULL;
+ rrset = msg->rrset_first;
+
+ /* At this point, we brutally remove ALL rrsets that aren't
+ * children of the originating zone. The idea here is that,
+ * as far as we know, the server that we contacted is ONLY
+ * authoritative for the originating zone. It, of course, MAY
+ * be authoriative for any other zones, and of course, MAY
+ * NOT be authoritative for some subdomains of the originating
+ * zone. */
+ while(rrset) {
+
+ /* skip DNAME records -- they will always be followed by a
+ * synthesized CNAME, which will be relevant.
+ * FIXME: should this do something differently with DNAME
+ * rrsets NOT in Section.ANSWER? */
+ /* But since DNAME records are also subdomains of the zone,
+ * same check can be used */
+
+ if(!pkt_sub(pkt, rrset->dname, zonename)) {
+ remove_rrset("sanitize: removing potential poison "
+ "RRset:", pkt, msg, prev, &rrset);
+ continue;
+ }
+ prev = rrset;
+ rrset = rrset->rrset_all_next;
+ }
return 1;
}
int
scrub_message(ldns_buffer* pkt, struct msg_parse* msg,
- struct query_info* qinfo, uint8_t* zonename, size_t zonelen,
- struct region* region)
+ struct query_info* qinfo, uint8_t* zonename, struct region* region)
{
/* things to check:
* if qdcount > 0 : qinfo.
return 0;
}
- /* normalize the response */
+ /* normalize the response, this cleans up the additional. */
if(!scrub_normalize(pkt, msg, qinfo, region))
return 0;
+ /* delete all out-of-zone information */
+ if(!scrub_sanitize(pkt, msg, zonename))
+ return 0;
return 1;
}
return f;
}
-/** Calculate hash value for rrset in packet. */
-static hashvalue_t
+hashvalue_t
pkt_hash_rrset(ldns_buffer* pkt, uint8_t* dname, uint16_t type,
uint16_t dclass, uint32_t rrset_flags)
{
}
-/**
- * Lookup in msg hashtable to find a rrset
- */
-static struct rrset_parse*
-hashtable_lookup(struct msg_parse* msg, ldns_buffer* pkt, hashvalue_t h,
- uint32_t rrset_flags, uint8_t* dname, size_t dnamelen,
+struct rrset_parse*
+msgparse_hashtable_lookup(struct msg_parse* msg, ldns_buffer* pkt,
+ hashvalue_t h, uint32_t rrset_flags, uint8_t* dname, size_t dnamelen,
uint16_t type, uint16_t dclass)
{
struct rrset_parse* p = msg->hashtable[h & (PARSE_TABLE_SIZE-1)];
return 0;
}
-/** remove rrset from hash list */
-static void
-bucket_remove(struct msg_parse* msg, struct rrset_parse* rrset)
+void
+msgparse_bucket_remove(struct msg_parse* msg, struct rrset_parse* rrset)
{
struct rrset_parse** p;
p = &msg->hashtable[ rrset->hash & (PARSE_TABLE_SIZE-1) ];
return dataset;
}
/* changeover the type of the rrset to data set */
- bucket_remove(msg, dataset);
+ msgparse_bucket_remove(msg, dataset);
/* insert into new hash bucket */
dataset->rrset_bucket_next = msg->hashtable[hash&(PARSE_TABLE_SIZE-1)];
msg->hashtable[hash&(PARSE_TABLE_SIZE-1)] = dataset;
ldns_buffer_current(pkt), &covtype)) {
*hash = pkt_hash_rrset(pkt, dname, covtype, dclass,
*rrset_flags);
- *rrset_prev = hashtable_lookup(msg, pkt, *hash, *rrset_flags,
- dname, dnamelen, covtype, dclass);
+ *rrset_prev = msgparse_hashtable_lookup(msg, pkt, *hash,
+ *rrset_flags, dname, dnamelen, covtype, dclass);
if(!*rrset_prev && covtype == LDNS_RR_TYPE_NSEC) {
/* if NSEC try with NSEC apex bit twiddled */
*rrset_flags ^= PACKED_RRSET_NSEC_AT_APEX;
*hash = pkt_hash_rrset(pkt, dname, covtype, dclass,
*rrset_flags);
- *rrset_prev = hashtable_lookup(msg, pkt, *hash,
- *rrset_flags, dname, dnamelen, covtype, dclass);
+ *rrset_prev = msgparse_hashtable_lookup(msg, pkt,
+ *hash, *rrset_flags, dname, dnamelen, covtype,
+ dclass);
}
if(*rrset_prev) {
*prev_dname_first = (*rrset_prev)->dname;
/* find matching rrsig */
*hash = pkt_hash_rrset(pkt, dname, LDNS_RR_TYPE_RRSIG,
dclass, *rrset_flags);
- *rrset_prev = hashtable_lookup(msg, pkt, *hash, *rrset_flags,
- dname, dnamelen, LDNS_RR_TYPE_RRSIG, dclass);
+ *rrset_prev = msgparse_hashtable_lookup(msg, pkt, *hash,
+ *rrset_flags, dname, dnamelen, LDNS_RR_TYPE_RRSIG,
+ dclass);
if(*rrset_prev && rrset_has_sigover(pkt, *rrset_prev, type,
&hasother)) {
/* yes! */
}
*hash = pkt_hash_rrset(pkt, dname, type, dclass, *rrset_flags);
- *rrset_prev = hashtable_lookup(msg, pkt, *hash, *rrset_flags,
+ *rrset_prev = msgparse_hashtable_lookup(msg, pkt, *hash, *rrset_flags,
dname, dnamelen, type, dclass);
if(*rrset_prev)
*prev_dname_first = (*rrset_prev)->dname;
projects / thirdparty / unbound.git / commitdiff
