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dnsmasq: Backport some security updates

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This fixes the following security problems in dnsmasq:
* CVE-2020-25681:
  Dnsmasq versions before 2.83 is susceptible to a heap-based buffer
  overflow in sort_rrset() when DNSSEC is used. This can allow a remote
  attacker to write arbitrary data into target device's memory that can
  lead to memory corruption and other unexpected behaviors on the target
  device.
* CVE-2020-25682:
  Dnsmasq versions before 2.83 is susceptible to buffer overflow in
  extract_name() function due to missing length check, when DNSSEC is
  enabled. This can allow a remote attacker to cause memory corruption
  on the target device.
* CVE-2020-25683:
  Dnsmasq version before 2.83 is susceptible to a heap-based buffer
  overflow when DNSSEC is enabled. A remote attacker, who can create
  valid DNS replies, could use this flaw to cause an overflow in a heap-
  allocated memory. This flaw is caused by the lack of length checks in
  rtc1035.c:extract_name(), which could be abused to make the code
  execute memcpy() with a negative size in get_rdata() and cause a crash
  in Dnsmasq, resulting in a Denial of Service.
* CVE-2020-25684:
  A lack of proper address/port check implemented in Dnsmasq version <
  2.83 reply_query function makes forging replies easier to an off-path
  attacker.
* CVE-2020-25685:
  A lack of query resource name (RRNAME) checks implemented in Dnsmasq's
  versions before 2.83 reply_query function allows remote attackers to
  spoof DNS traffic that can lead to DNS cache poisoning.
* CVE-2020-25686:
  Multiple DNS query requests for the same resource name (RRNAME) by
  Dnsmasq versions before 2.83 allows for remote attackers to spoof DNS
  traffic, using a birthday attack (RFC 5452), that can lead to DNS
  cache poisoning.
* CVE-2020-25687:
  Dnsmasq versions before 2.83 is vulnerable to a heap-based buffer
  overflow with large memcpy in sort_rrset() when DNSSEC is enabled. A
  remote attacker, who can create valid DNS replies, could use this flaw
  to cause an overflow in a heap-allocated memory. This flaw is caused
  by the lack of length checks in rtc1035.c:extract_name(), which could
  be abused to make the code execute memcpy() with a negative size in
  sort_rrset() and cause a crash in dnsmasq, resulting in a Denial of
  Service.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
This commit is contained in:
Hauke Mehrtens 2021-01-11 01:03:03 +01:00
parent 733e62a8e1
commit 8055e38794
14 changed files with 2280 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
package/network/services/dnsmasq/Makefile
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@ -10,7 +10,7 @@ include $(TOPDIR)/rules.mk
PKG_NAME:=dnsmasq
PKG_UPSTREAM_VERSION:=2.80
PKG_VERSION:=$(subst test,~~test,$(subst rc,~rc,$(PKG_UPSTREAM_VERSION)))
PKG_RELEASE:=16.1
PKG_RELEASE:=16.2
PKG_SOURCE:=$(PKG_NAME)-$(PKG_UPSTREAM_VERSION).tar.xz
PKG_SOURCE_URL:=http://thekelleys.org.uk/dnsmasq

375
package/network/services/dnsmasq/patches/0102-Fix-remote-buffer-overflow-CERT-VU-434904.patch Normal file
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@ -0,0 +1,375 @@
From 4e96a4be685c9e4445f6ee79ad0b36b9119b502a Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Wed, 11 Nov 2020 23:25:04 +0000
Subject: Fix remote buffer overflow CERT VU#434904
The problem is in the sort_rrset() function and allows a remote
attacker to overwrite memory. Any dnsmasq instance with DNSSEC
enabled is vulnerable.
---
CHANGELOG | 7 +-
src/dnssec.c | 273 ++++++++++++++++++++++++++++-----------------------
2 files changed, 158 insertions(+), 122 deletions(-)
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,9 @@
+ Fix a remote buffer overflow problem in the DNSSEC code. Any
+ dnsmasq with DNSSEC compiled in and enabled is vulnerable to this,
+ referenced by CERT VU#434904.
+
+
+>>>>>>> Fix remote buffer overflow CERT VU#434904
version 2.81
Impove cache behaviour for TCP connections. For ease of
implementaion, dnsmasq has always forked a new process to handle
--- a/src/dnssec.c
+++ b/src/dnssec.c
@@ -222,138 +222,147 @@ static int check_date_range(u32 date_sta
&& serial_compare_32(curtime, date_end) == SERIAL_LT;
}
-/* Return bytes of canonicalised rdata, when the return value is zero, the remaining
- data, pointed to by *p, should be used raw. */
-static int get_rdata(struct dns_header *header, size_t plen, unsigned char *end, char *buff, int bufflen,
- unsigned char **p, u16 **desc)
+/* Return bytes of canonicalised rrdata one by one.
+ Init state->ip with the RR, and state->end with the end of same.
+ Init state->op to NULL.
+ Init state->desc to RR descriptor.
+ Init state->buff with a MAXDNAME * 2 buffer.
+
+ After each call which returns 1, state->op points to the next byte of data.
+ On returning 0, the end has been reached.
+*/
+struct rdata_state {
+ u16 *desc;
+ size_t c;
+ unsigned char *end, *ip, *op;
+ char *buff;
+};
+
+static int get_rdata(struct dns_header *header, size_t plen, struct rdata_state *state)
{
- int d = **desc;
+ int d;
- /* No more data needs mangling */
- if (d == (u16)-1)
+ if (state->op && state->c != 1)
{
- /* If there's more data than we have space for, just return what fits,
- we'll get called again for more chunks */
- if (end - *p > bufflen)
- {
- memcpy(buff, *p, bufflen);
- *p += bufflen;
- return bufflen;
- }
-
- return 0;
+ state->op++;
+ state->c--;
+ return 1;
}
-
- (*desc)++;
-
- if (d == 0 && extract_name(header, plen, p, buff, 1, 0))
- /* domain-name, canonicalise */
- return to_wire(buff);
- else
- {
- /* plain data preceding a domain-name, don't run off the end of the data */
- if ((end - *p) < d)
- d = end - *p;
+
+ while (1)
+ {
+ d = *(state->desc);
- if (d != 0)
+ if (d == (u16)-1)
{
- memcpy(buff, *p, d);
- *p += d;
+ /* all the bytes to the end. */
+ if ((state->c = state->end - state->ip) != 0)
+ {
+ state->op = state->ip;
+ state->ip = state->end;;
+ }
+ else
+ return 0;
+ }
+ else
+ {
+ state->desc++;
+
+ if (d == (u16)0)
+ {
+ /* domain-name, canonicalise */
+ int len;
+
+ if (!extract_name(header, plen, &state->ip, state->buff, 1, 0) ||
+ (len = to_wire(state->buff)) == 0)
+ continue;
+
+ state->c = len;
+ state->op = (unsigned char *)state->buff;
+ }
+ else
+ {
+ /* plain data preceding a domain-name, don't run off the end of the data */
+ if ((state->end - state->ip) < d)
+ d = state->end - state->ip;
+
+ if (d == 0)
+ continue;
+
+ state->op = state->ip;
+ state->c = d;
+ state->ip += d;
+ }
}
- return d;
+ return 1;
}
}
-/* Bubble sort the RRset into the canonical order.
- Note that the byte-streams from two RRs may get unsynced: consider
- RRs which have two domain-names at the start and then other data.
- The domain-names may have different lengths in each RR, but sort equal
-
- ------------
- |abcde|fghi|
- ------------
- |abcd|efghi|
- ------------
-
- leaving the following bytes as deciding the order. Hence the nasty left1 and left2 variables.
-*/
+/* Bubble sort the RRset into the canonical order. */
static int sort_rrset(struct dns_header *header, size_t plen, u16 *rr_desc, int rrsetidx,
unsigned char **rrset, char *buff1, char *buff2)
{
- int swap, quit, i, j;
+ int swap, i, j;
do
{
for (swap = 0, i = 0; i < rrsetidx-1; i++)
{
- int rdlen1, rdlen2, left1, left2, len1, len2, len, rc;
- u16 *dp1, *dp2;
- unsigned char *end1, *end2;
+ int rdlen1, rdlen2;
+ struct rdata_state state1, state2;
+
/* Note that these have been determined to be OK previously,
so we don't need to check for NULL return here. */
- unsigned char *p1 = skip_name(rrset[i], header, plen, 10);
- unsigned char *p2 = skip_name(rrset[i+1], header, plen, 10);
-
- p1 += 8; /* skip class, type, ttl */
- GETSHORT(rdlen1, p1);
- end1 = p1 + rdlen1;
-
- p2 += 8; /* skip class, type, ttl */
- GETSHORT(rdlen2, p2);
- end2 = p2 + rdlen2;
-
- dp1 = dp2 = rr_desc;
-
- for (quit = 0, left1 = 0, left2 = 0, len1 = 0, len2 = 0; !quit;)
+ state1.ip = skip_name(rrset[i], header, plen, 10);
+ state2.ip = skip_name(rrset[i+1], header, plen, 10);
+ state1.op = state2.op = NULL;
+ state1.buff = buff1;
+ state2.buff = buff2;
+ state1.desc = state2.desc = rr_desc;
+
+ state1.ip += 8; /* skip class, type, ttl */
+ GETSHORT(rdlen1, state1.ip);
+ if (!CHECK_LEN(header, state1.ip, plen, rdlen1))
+ return rrsetidx; /* short packet */
+ state1.end = state1.ip + rdlen1;
+
+ state2.ip += 8; /* skip class, type, ttl */
+ GETSHORT(rdlen2, state2.ip);
+ if (!CHECK_LEN(header, state2.ip, plen, rdlen2))
+ return rrsetidx; /* short packet */
+ state2.end = state2.ip + rdlen2;
+
+ while (1)
{
- if (left1 != 0)
- memmove(buff1, buff1 + len1 - left1, left1);
-
- if ((len1 = get_rdata(header, plen, end1, buff1 + left1, (MAXDNAME * 2) - left1, &p1, &dp1)) == 0)
- {
- quit = 1;
- len1 = end1 - p1;
- memcpy(buff1 + left1, p1, len1);
- }
- len1 += left1;
-
- if (left2 != 0)
- memmove(buff2, buff2 + len2 - left2, left2);
-
- if ((len2 = get_rdata(header, plen, end2, buff2 + left2, (MAXDNAME *2) - left2, &p2, &dp2)) == 0)
- {
- quit = 1;
- len2 = end2 - p2;
- memcpy(buff2 + left2, p2, len2);
- }
- len2 += left2;
-
- if (len1 > len2)
- left1 = len1 - len2, left2 = 0, len = len2;
- else
- left2 = len2 - len1, left1 = 0, len = len1;
+ int ok1, ok2;
- rc = (len == 0) ? 0 : memcmp(buff1, buff2, len);
-
- if (rc > 0 || (rc == 0 && quit && len1 > len2))
- {
- unsigned char *tmp = rrset[i+1];
- rrset[i+1] = rrset[i];
- rrset[i] = tmp;
- swap = quit = 1;
- }
- else if (rc == 0 && quit && len1 == len2)
+ ok1 = get_rdata(header, plen, &state1);
+ ok2 = get_rdata(header, plen, &state2);
+
+ if (!ok1 && !ok2)
{
/* Two RRs are equal, remove one copy. RFC 4034, para 6.3 */
for (j = i+1; j < rrsetidx-1; j++)
rrset[j] = rrset[j+1];
rrsetidx--;
i--;
+ break;
+ }
+ else if (ok1 && (!ok2 || *state1.op > *state2.op))
+ {
+ unsigned char *tmp = rrset[i+1];
+ rrset[i+1] = rrset[i];
+ rrset[i] = tmp;
+ swap = 1;
+ break;
}
- else if (rc < 0)
- quit = 1;
+ else if (ok2 && (!ok1 || *state2.op > *state1.op))
+ break;
+
+ /* arrive here when bytes are equal, go round the loop again
+ and compare the next ones. */
}
}
} while (swap);
@@ -549,15 +558,18 @@ static int validate_rrset(time_t now, st
wire_len = to_wire(keyname);
hash->update(ctx, (unsigned int)wire_len, (unsigned char*)keyname);
from_wire(keyname);
+
+#define RRBUFLEN 300 /* Most RRs are smaller than this. */
for (i = 0; i < rrsetidx; ++i)
{
- int seg;
- unsigned char *end, *cp;
- u16 len, *dp;
+ int j;
+ struct rdata_state state;
+ u16 len;
+ unsigned char rrbuf[RRBUFLEN];
p = rrset[i];
-
+
if (!extract_name(header, plen, &p, name, 1, 10))
return STAT_BOGUS;
@@ -566,12 +578,11 @@ static int validate_rrset(time_t now, st
/* if more labels than in RRsig name, hash *.<no labels in rrsig labels field> 4035 5.3.2 */
if (labels < name_labels)
{
- int k;
- for (k = name_labels - labels; k != 0; k--)
+ for (j = name_labels - labels; j != 0; j--)
{
while (*name_start != '.' && *name_start != 0)
name_start++;
- if (k != 1 && *name_start == '.')
+ if (j != 1 && *name_start == '.')
name_start++;
}
@@ -592,24 +603,44 @@ static int validate_rrset(time_t now, st
if (!CHECK_LEN(header, p, plen, rdlen))
return STAT_BOGUS;
- end = p + rdlen;
-
- /* canonicalise rdata and calculate length of same, use name buffer as workspace.
- Note that name buffer is twice MAXDNAME long in DNSSEC mode. */
- cp = p;
- dp = rr_desc;
- for (len = 0; (seg = get_rdata(header, plen, end, name, MAXDNAME * 2, &cp, &dp)) != 0; len += seg);
- len += end - cp;
- len = htons(len);
+ /* canonicalise rdata and calculate length of same, use
+ name buffer as workspace for get_rdata. */
+ state.ip = p;
+ state.op = NULL;
+ state.desc = rr_desc;
+ state.buff = name;
+ state.end = p + rdlen;
+
+ for (j = 0; get_rdata(header, plen, &state); j++)
+ if (j < RRBUFLEN)
+ rrbuf[j] = *state.op;
+
+ len = htons((u16)j);
hash->update(ctx, 2, (unsigned char *)&len);
+
+ /* If the RR is shorter than RRBUFLEN (most of them, in practice)
+ then we can just digest it now. If it exceeds RRBUFLEN we have to
+ go back to the start and do it in chunks. */
+ if (j >= RRBUFLEN)
+ {
+ state.ip = p;
+ state.op = NULL;
+ state.desc = rr_desc;
+
+ for (j = 0; get_rdata(header, plen, &state); j++)
+ {
+ rrbuf[j] = *state.op;
+
+ if (j == RRBUFLEN - 1)
+ {
+ hash->update(ctx, RRBUFLEN, rrbuf);
+ j = -1;
+ }
+ }
+ }
- /* Now canonicalise again and digest. */
- cp = p;
- dp = rr_desc;
- while ((seg = get_rdata(header, plen, end, name, MAXDNAME * 2, &cp, &dp)))
- hash->update(ctx, seg, (unsigned char *)name);
- if (cp != end)
- hash->update(ctx, end - cp, cp);
+ if (j != 0)
+ hash->update(ctx, j, rrbuf);
}
hash->digest(ctx, hash->digest_size, digest);

106
package/network/services/dnsmasq/patches/0103-Check-destination-of-DNS-UDP-query-replies.patch Normal file
View File

@ -0,0 +1,106 @@
From 257ac0c5f7732cbc6aa96fdd3b06602234593aca Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Thu, 12 Nov 2020 18:49:23 +0000
Subject: Check destination of DNS UDP query replies.
At any time, dnsmasq will have a set of sockets open, bound to
random ports, on which it sends queries to upstream nameservers.
This patch fixes the existing problem that a reply for ANY in-flight
query would be accepted via ANY open port, which increases the
chances of an attacker flooding answers "in the blind" in an
attempt to poison the DNS cache. CERT VU#434904 refers.
---
CHANGELOG | 6 +++++-
src/forward.c | 37 ++++++++++++++++++++++++++++---------
2 files changed, 33 insertions(+), 10 deletions(-)
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -2,8 +2,12 @@
dnsmasq with DNSSEC compiled in and enabled is vulnerable to this,
referenced by CERT VU#434904.
+ Be sure to only accept UDP DNS query replies at the address
+ from which the query was originated. This keeps as much entropy
+ in the {query-ID, random-port} tuple as possible, help defeat
+ cache poisoning attacks. Refer: CERT VU#434904.
+
->>>>>>> Fix remote buffer overflow CERT VU#434904
version 2.81
Impove cache behaviour for TCP connections. For ease of
implementaion, dnsmasq has always forked a new process to handle
--- a/src/forward.c
+++ b/src/forward.c
@@ -16,7 +16,7 @@
#include "dnsmasq.h"
-static struct frec *lookup_frec(unsigned short id, void *hash);
+static struct frec *lookup_frec(unsigned short id, int fd, int family, void *hash);
static struct frec *lookup_frec_by_sender(unsigned short id,
union mysockaddr *addr,
void *hash);
@@ -797,7 +797,7 @@ void reply_query(int fd, int family, tim
crc = questions_crc(header, n, daemon->namebuff);
#endif
- if (!(forward = lookup_frec(ntohs(header->id), hash)))
+ if (!(forward = lookup_frec(ntohs(header->id), fd, family, hash)))
return;
#ifdef HAVE_DUMPFILE
@@ -2289,14 +2289,25 @@ struct frec *get_new_frec(time_t now, in
}
/* crc is all-ones if not known. */
-static struct frec *lookup_frec(unsigned short id, void *hash)
+static struct frec *lookup_frec(unsigned short id, int fd, int family, void *hash)
{
struct frec *f;
for(f = daemon->frec_list; f; f = f->next)
if (f->sentto && f->new_id == id &&
(!hash || memcmp(hash, f->hash, HASH_SIZE) == 0))
- return f;
+ {
+ /* sent from random port */
+ if (family == AF_INET && f->rfd4 && f->rfd4->fd == fd)
+ return f;
+
+ if (family == AF_INET6 && f->rfd6 && f->rfd6->fd == fd)
+ return f;
+
+ /* sent to upstream from bound socket. */
+ if (f->sentto->sfd && f->sentto->sfd->fd == fd)
+ return f;
+ }
return NULL;
}
@@ -2357,12 +2368,20 @@ void server_gone(struct server *server)
static unsigned short get_id(void)
{
unsigned short ret = 0;
+ struct frec *f;
- do
- ret = rand16();
- while (lookup_frec(ret, NULL));
-
- return ret;
+ while (1)
+ {
+ ret = rand16();
+
+ /* ensure id is unique. */
+ for (f = daemon->frec_list; f; f = f->next)
+ if (f->sentto && f->new_id == ret)
+ break;
+
+ if (!f)
+ return ret;
+ }
}

581
package/network/services/dnsmasq/patches/0104-Use-SHA-256-to-provide-security-against-DNS-cache-po.patch Normal file
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@ -0,0 +1,581 @@
From 2d765867c597db18be9d876c9c17e2c0fe1953cd Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Thu, 12 Nov 2020 22:06:07 +0000
Subject: Use SHA-256 to provide security against DNS cache poisoning.
Use the SHA-256 hash function to verify that DNS answers
received are for the questions originally asked. This replaces
the slightly insecure SHA-1 (when compiled with DNSSEC) or
the very insecure CRC32 (otherwise). Refer: CERT VU#434904.
---
CHANGELOG | 5 +
Makefile | 3 +-
bld/Android.mk | 2 +-
src/dnsmasq.h | 11 +-
src/dnssec.c | 31 -----
src/forward.c | 43 ++-----
src/hash_questions.c | 281 +++++++++++++++++++++++++++++++++++++++++++
src/rfc1035.c | 49 --------
8 files changed, 301 insertions(+), 124 deletions(-)
create mode 100644 src/hash_questions.c
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -7,6 +7,11 @@
in the {query-ID, random-port} tuple as possible, help defeat
cache poisoning attacks. Refer: CERT VU#434904.
+ Use the SHA-256 hash function to verify that DNS answers
+ received are for the questions originally asked. This replaces
+ the slightly insecure SHA-1 (when compiled with DNSSEC) or
+ the very insecure CRC32 (otherwise). Refer: CERT VU#434904.
+
version 2.81
Impove cache behaviour for TCP connections. For ease of
--- a/Makefile
+++ b/Makefile
@@ -77,7 +77,8 @@ objs = cache.o rfc1035.o util.o option.o
helper.o tftp.o log.o conntrack.o dhcp6.o rfc3315.o \
dhcp-common.o outpacket.o radv.o slaac.o auth.o ipset.o \
domain.o dnssec.o blockdata.o tables.o loop.o inotify.o \
- poll.o rrfilter.o edns0.o arp.o crypto.o dump.o ubus.o metrics.o
+ poll.o rrfilter.o edns0.o arp.o crypto.o dump.o ubus.o \
+ metrics.o hash_questions.o
hdrs = dnsmasq.h config.h dhcp-protocol.h dhcp6-protocol.h \
dns-protocol.h radv-protocol.h ip6addr.h metrics.h
--- a/bld/Android.mk
+++ b/bld/Android.mk
@@ -11,7 +11,7 @@ LOCAL_SRC_FILES := bpf.c cache.c dbus.c
radv.c slaac.c auth.c ipset.c domain.c \
dnssec.c dnssec-openssl.c blockdata.c tables.c \
loop.c inotify.c poll.c rrfilter.c edns0.c arp.c \
- crypto.c dump.c ubus.c
+ crypto.c dump.c ubus.c metrics.c hash_questions.c
LOCAL_MODULE := dnsmasq
--- a/src/dnsmasq.h
+++ b/src/dnsmasq.h
@@ -644,11 +644,7 @@ struct hostsfile {
#define FREC_TEST_PKTSZ 256
#define FREC_HAS_EXTRADATA 512
-#ifdef HAVE_DNSSEC
-#define HASH_SIZE 20 /* SHA-1 digest size */
-#else
-#define HASH_SIZE sizeof(int)
-#endif
+#define HASH_SIZE 32 /* SHA-256 digest size */
struct frec {
union mysockaddr source;
@@ -1199,7 +1195,6 @@ int check_for_bogus_wildcard(struct dns_
struct bogus_addr *baddr, time_t now);
int check_for_ignored_address(struct dns_header *header, size_t qlen, struct bogus_addr *baddr);
int check_for_local_domain(char *name, time_t now);
-unsigned int questions_crc(struct dns_header *header, size_t plen, char *name);
size_t resize_packet(struct dns_header *header, size_t plen,
unsigned char *pheader, size_t hlen);
int add_resource_record(struct dns_header *header, char *limit, int *truncp,
@@ -1227,9 +1222,11 @@ int dnssec_validate_reply(time_t now, st
int check_unsigned, int *neganswer, int *nons);
int dnskey_keytag(int alg, int flags, unsigned char *key, int keylen);
size_t filter_rrsigs(struct dns_header *header, size_t plen);
-unsigned char* hash_questions(struct dns_header *header, size_t plen, char *name);
int setup_timestamp(void);
+/* hash_questions.c */
+unsigned char *hash_questions(struct dns_header *header, size_t plen, char *name);
+
/* crypto.c */
const struct nettle_hash *hash_find(char *name);
int hash_init(const struct nettle_hash *hash, void **ctxp, unsigned char **digestp);
--- a/src/dnssec.c
+++ b/src/dnssec.c
@@ -2082,35 +2082,4 @@ size_t dnssec_generate_query(struct dns_
return ret;
}
-unsigned char* hash_questions(struct dns_header *header, size_t plen, char *name)
-{
- int q;
- unsigned int len;
- unsigned char *p = (unsigned char *)(header+1);
- const struct nettle_hash *hash;
- void *ctx;
- unsigned char *digest;
-
- if (!(hash = hash_find("sha1")) || !hash_init(hash, &ctx, &digest))
- return NULL;
-
- for (q = ntohs(header->qdcount); q != 0; q--)
- {
- if (!extract_name(header, plen, &p, name, 1, 4))
- break; /* bad packet */
-
- len = to_wire(name);
- hash->update(ctx, len, (unsigned char *)name);
- /* CRC the class and type as well */
- hash->update(ctx, 4, p);
-
- p += 4;
- if (!CHECK_LEN(header, p, plen, 0))
- break; /* bad packet */
- }
-
- hash->digest(ctx, hash->digest_size, digest);
- return digest;
-}
-
#endif /* HAVE_DNSSEC */
--- a/src/forward.c
+++ b/src/forward.c
@@ -248,19 +248,16 @@ static int forward_query(int udpfd, unio
union all_addr *addrp = NULL;
unsigned int flags = 0;
struct server *start = NULL;
-#ifdef HAVE_DNSSEC
void *hash = hash_questions(header, plen, daemon->namebuff);
+#ifdef HAVE_DNSSEC
int do_dnssec = 0;
-#else
- unsigned int crc = questions_crc(header, plen, daemon->namebuff);
- void *hash = &crc;
#endif
unsigned int gotname = extract_request(header, plen, daemon->namebuff, NULL);
unsigned char *oph = find_pseudoheader(header, plen, NULL, NULL, NULL, NULL);
(void)do_bit;
/* may be no servers available. */
- if (forward || (hash && (forward = lookup_frec_by_sender(ntohs(header->id), udpaddr, hash))))
+ if (forward || (forward = lookup_frec_by_sender(ntohs(header->id), udpaddr, hash)))
{
/* If we didn't get an answer advertising a maximal packet in EDNS,
fall back to 1280, which should work everywhere on IPv6.
@@ -761,9 +758,6 @@ void reply_query(int fd, int family, tim
size_t nn;
struct server *server;
void *hash;
-#ifndef HAVE_DNSSEC
- unsigned int crc;
-#endif
/* packet buffer overwritten */
daemon->srv_save = NULL;
@@ -790,12 +784,7 @@ void reply_query(int fd, int family, tim
if (difftime(now, server->pktsz_reduced) > UDP_TEST_TIME)
server->edns_pktsz = daemon->edns_pktsz;
-#ifdef HAVE_DNSSEC
hash = hash_questions(header, n, daemon->namebuff);
-#else
- hash = &crc;
- crc = questions_crc(header, n, daemon->namebuff);
-#endif
if (!(forward = lookup_frec(ntohs(header->id), fd, family, hash)))
return;
@@ -1100,8 +1089,7 @@ void reply_query(int fd, int family, tim
log_query(F_NOEXTRA | F_DNSSEC | F_IPV6, daemon->keyname, (union all_addr *)&(server->addr.in6.sin6_addr),
querystr("dnssec-query", querytype));
- if ((hash = hash_questions(header, nn, daemon->namebuff)))
- memcpy(new->hash, hash, HASH_SIZE);
+ memcpy(new->hash, hash_questions(header, nn, daemon->namebuff), HASH_SIZE);
new->new_id = get_id();
header->id = htons(new->new_id);
/* Save query for retransmission */
@@ -1937,15 +1925,9 @@ unsigned char *tcp_request(int confd, ti
if (!flags && last_server)
{
struct server *firstsendto = NULL;
-#ifdef HAVE_DNSSEC
- unsigned char *newhash, hash[HASH_SIZE];
- if ((newhash = hash_questions(header, (unsigned int)size, daemon->namebuff)))
- memcpy(hash, newhash, HASH_SIZE);
- else
- memset(hash, 0, HASH_SIZE);
-#else
- unsigned int crc = questions_crc(header, (unsigned int)size, daemon->namebuff);
-#endif
+ unsigned char hash[HASH_SIZE];
+ memcpy(hash, hash_questions(header, (unsigned int)size, daemon->namebuff), HASH_SIZE);
+
/* Loop round available servers until we succeed in connecting to one.
Note that this code subtly ensures that consecutive queries on this connection
which can go to the same server, do so. */
@@ -2068,20 +2050,11 @@ unsigned char *tcp_request(int confd, ti
/* If the crc of the question section doesn't match the crc we sent, then
someone might be attempting to insert bogus values into the cache by
sending replies containing questions and bogus answers. */
-#ifdef HAVE_DNSSEC
- newhash = hash_questions(header, (unsigned int)m, daemon->namebuff);
- if (!newhash || memcmp(hash, newhash, HASH_SIZE) != 0)
+ if (memcmp(hash, hash_questions(header, (unsigned int)m, daemon->namebuff), HASH_SIZE) != 0)
{
m = 0;
break;
}
-#else
- if (crc != questions_crc(header, (unsigned int)m, daemon->namebuff))
- {
- m = 0;
- break;
- }
-#endif
m = process_reply(header, now, last_server, (unsigned int)m,
option_bool(OPT_NO_REBIND) && !norebind, no_cache_dnssec, cache_secure, bogusanswer,
@@ -2295,7 +2268,7 @@ static struct frec *lookup_frec(unsigned
for(f = daemon->frec_list; f; f = f->next)
if (f->sentto && f->new_id == id &&
- (!hash || memcmp(hash, f->hash, HASH_SIZE) == 0))
+ (memcmp(hash, f->hash, HASH_SIZE) == 0))
{
/* sent from random port */
if (family == AF_INET && f->rfd4 && f->rfd4->fd == fd)
--- /dev/null
+++ b/src/hash_questions.c
@@ -0,0 +1,281 @@
+/* Copyright (c) 2012-2020 Simon Kelley
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; version 2 dated June, 1991, or
+ (at your option) version 3 dated 29 June, 2007.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+
+/* Hash the question section. This is used to safely detect query
+ retransmission and to detect answers to questions we didn't ask, which
+ might be poisoning attacks. Note that we decode the name rather
+ than CRC the raw bytes, since replies might be compressed differently.
+ We ignore case in the names for the same reason.
+
+ The hash used is SHA-256. If we're building with DNSSEC support,
+ we use the Nettle cypto library. If not, we prefer not to
+ add a dependency on Nettle, and use a stand-alone implementaion.
+*/
+
+#include "dnsmasq.h"
+
+#ifdef HAVE_DNSSEC
+unsigned char *hash_questions(struct dns_header *header, size_t plen, char *name)
+{
+ int q;
+ unsigned char *p = (unsigned char *)(header+1);
+ const struct nettle_hash *hash;
+ void *ctx;
+ unsigned char *digest;
+
+ if (!(hash = hash_find("sha256")) || !hash_init(hash, &ctx, &digest))
+ {
+ /* don't think this can ever happen. */
+ static unsigned char dummy[HASH_SIZE];
+ static int warned = 0;
+
+ if (warned)
+ my_syslog(LOG_ERR, _("Failed to create SHA-256 hash object"));
+ warned = 1;
+
+ return dummy;
+ }
+
+ for (q = ntohs(header->qdcount); q != 0; q--)
+ {
+ char *cp, c;
+
+ if (!extract_name(header, plen, &p, name, 1, 4))
+ break; /* bad packet */
+
+ for (cp = name; (c = *cp); cp++)
+ if (c >= 'A' && c <= 'Z')
+ *cp += 'a' - 'A';
+
+ hash->update(ctx, cp - name, (unsigned char *)name);
+ /* CRC the class and type as well */
+ hash->update(ctx, 4, p);
+
+ p += 4;
+ if (!CHECK_LEN(header, p, plen, 0))
+ break; /* bad packet */
+ }
+
+ hash->digest(ctx, hash->digest_size, digest);
+ return digest;
+}
+
+#else /* HAVE_DNSSEC */
+
+#define SHA256_BLOCK_SIZE 32 // SHA256 outputs a 32 byte digest
+typedef unsigned char BYTE; // 8-bit byte
+typedef unsigned int WORD; // 32-bit word, change to "long" for 16-bit machines
+
+typedef struct {
+ BYTE data[64];
+ WORD datalen;
+ unsigned long long bitlen;
+ WORD state[8];
+} SHA256_CTX;
+
+static void sha256_init(SHA256_CTX *ctx);
+static void sha256_update(SHA256_CTX *ctx, const BYTE data[], size_t len);
+static void sha256_final(SHA256_CTX *ctx, BYTE hash[]);
+
+
+unsigned char *hash_questions(struct dns_header *header, size_t plen, char *name)
+{
+ int q;
+ unsigned char *p = (unsigned char *)(header+1);
+ SHA256_CTX ctx;
+ static BYTE digest[SHA256_BLOCK_SIZE];
+
+ sha256_init(&ctx);
+
+ for (q = ntohs(header->qdcount); q != 0; q--)
+ {
+ char *cp, c;
+
+ if (!extract_name(header, plen, &p, name, 1, 4))
+ break; /* bad packet */
+
+ for (cp = name; (c = *cp); cp++)
+ if (c >= 'A' && c <= 'Z')
+ *cp += 'a' - 'A';
+
+ sha256_update(&ctx, (BYTE *)name, cp - name);
+ /* CRC the class and type as well */
+ sha256_update(&ctx, (BYTE *)p, 4);
+
+ p += 4;
+ if (!CHECK_LEN(header, p, plen, 0))
+ break; /* bad packet */
+ }
+
+ sha256_final(&ctx, digest);
+ return (unsigned char *)digest;
+}
+
+/* Code from here onwards comes from https://github.com/B-Con/crypto-algorithms
+ and was written by Brad Conte (brad@bradconte.com), to whom all credit is given.
+
+ This code is in the public domain, and the copyright notice at the head of this
+ file does not apply to it.
+*/
+
+
+/****************************** MACROS ******************************/
+#define ROTLEFT(a,b) (((a) << (b)) | ((a) >> (32-(b))))
+#define ROTRIGHT(a,b) (((a) >> (b)) | ((a) << (32-(b))))
+
+#define CH(x,y,z) (((x) & (y)) ^ (~(x) & (z)))
+#define MAJ(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
+#define EP0(x) (ROTRIGHT(x,2) ^ ROTRIGHT(x,13) ^ ROTRIGHT(x,22))
+#define EP1(x) (ROTRIGHT(x,6) ^ ROTRIGHT(x,11) ^ ROTRIGHT(x,25))
+#define SIG0(x) (ROTRIGHT(x,7) ^ ROTRIGHT(x,18) ^ ((x) >> 3))
+#define SIG1(x) (ROTRIGHT(x,17) ^ ROTRIGHT(x,19) ^ ((x) >> 10))
+
+/**************************** VARIABLES *****************************/
+static const WORD k[64] = {
+ 0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5,
+ 0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174,
+ 0xe49b69c1,0xefbe4786,0x0fc19dc6,0x240ca1cc,0x2de92c6f,0x4a7484aa,0x5cb0a9dc,0x76f988da,
+ 0x983e5152,0xa831c66d,0xb00327c8,0xbf597fc7,0xc6e00bf3,0xd5a79147,0x06ca6351,0x14292967,
+ 0x27b70a85,0x2e1b2138,0x4d2c6dfc,0x53380d13,0x650a7354,0x766a0abb,0x81c2c92e,0x92722c85,
+ 0xa2bfe8a1,0xa81a664b,0xc24b8b70,0xc76c51a3,0xd192e819,0xd6990624,0xf40e3585,0x106aa070,
+ 0x19a4c116,0x1e376c08,0x2748774c,0x34b0bcb5,0x391c0cb3,0x4ed8aa4a,0x5b9cca4f,0x682e6ff3,
+ 0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208,0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2
+};
+
+/*********************** FUNCTION DEFINITIONS ***********************/
+static void sha256_transform(SHA256_CTX *ctx, const BYTE data[])
+{
+ WORD a, b, c, d, e, f, g, h, i, j, t1, t2, m[64];
+
+ for (i = 0, j = 0; i < 16; ++i, j += 4)
+ m[i] = (data[j] << 24) | (data[j + 1] << 16) | (data[j + 2] << 8) | (data[j + 3]);
+ for ( ; i < 64; ++i)
+ m[i] = SIG1(m[i - 2]) + m[i - 7] + SIG0(m[i - 15]) + m[i - 16];
+
+ a = ctx->state[0];
+ b = ctx->state[1];
+ c = ctx->state[2];
+ d = ctx->state[3];
+ e = ctx->state[4];
+ f = ctx->state[5];
+ g = ctx->state[6];
+ h = ctx->state[7];
+
+ for (i = 0; i < 64; ++i)
+ {
+ t1 = h + EP1(e) + CH(e,f,g) + k[i] + m[i];
+ t2 = EP0(a) + MAJ(a,b,c);
+ h = g;
+ g = f;
+ f = e;
+ e = d + t1;
+ d = c;
+ c = b;
+ b = a;
+ a = t1 + t2;
+ }
+
+ ctx->state[0] += a;
+ ctx->state[1] += b;
+ ctx->state[2] += c;
+ ctx->state[3] += d;
+ ctx->state[4] += e;
+ ctx->state[5] += f;
+ ctx->state[6] += g;
+ ctx->state[7] += h;
+}
+
+static void sha256_init(SHA256_CTX *ctx)
+{
+ ctx->datalen = 0;
+ ctx->bitlen = 0;
+ ctx->state[0] = 0x6a09e667;
+ ctx->state[1] = 0xbb67ae85;
+ ctx->state[2] = 0x3c6ef372;
+ ctx->state[3] = 0xa54ff53a;
+ ctx->state[4] = 0x510e527f;
+ ctx->state[5] = 0x9b05688c;
+ ctx->state[6] = 0x1f83d9ab;
+ ctx->state[7] = 0x5be0cd19;
+}
+
+static void sha256_update(SHA256_CTX *ctx, const BYTE data[], size_t len)
+{
+ WORD i;
+
+ for (i = 0; i < len; ++i)
+ {
+ ctx->data[ctx->datalen] = data[i];
+ ctx->datalen++;
+ if (ctx->datalen == 64) {
+ sha256_transform(ctx, ctx->data);
+ ctx->bitlen += 512;
+ ctx->datalen = 0;
+ }
+ }
+}
+
+static void sha256_final(SHA256_CTX *ctx, BYTE hash[])
+{
+ WORD i;
+
+ i = ctx->datalen;
+
+ // Pad whatever data is left in the buffer.
+ if (ctx->datalen < 56)
+ {
+ ctx->data[i++] = 0x80;
+ while (i < 56)
+ ctx->data[i++] = 0x00;
+ }
+ else
+ {
+ ctx->data[i++] = 0x80;
+ while (i < 64)
+ ctx->data[i++] = 0x00;
+ sha256_transform(ctx, ctx->data);
+ memset(ctx->data, 0, 56);
+ }
+
+ // Append to the padding the total message's length in bits and transform.
+ ctx->bitlen += ctx->datalen * 8;
+ ctx->data[63] = ctx->bitlen;
+ ctx->data[62] = ctx->bitlen >> 8;
+ ctx->data[61] = ctx->bitlen >> 16;
+ ctx->data[60] = ctx->bitlen >> 24;
+ ctx->data[59] = ctx->bitlen >> 32;
+ ctx->data[58] = ctx->bitlen >> 40;
+ ctx->data[57] = ctx->bitlen >> 48;
+ ctx->data[56] = ctx->bitlen >> 56;
+ sha256_transform(ctx, ctx->data);
+
+ // Since this implementation uses little endian byte ordering and SHA uses big endian,
+ // reverse all the bytes when copying the final state to the output hash.
+ for (i = 0; i < 4; ++i)
+ {
+ hash[i] = (ctx->state[0] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 4] = (ctx->state[1] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 8] = (ctx->state[2] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 12] = (ctx->state[3] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 16] = (ctx->state[4] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 20] = (ctx->state[5] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 24] = (ctx->state[6] >> (24 - i * 8)) & 0x000000ff;
+ hash[i + 28] = (ctx->state[7] >> (24 - i * 8)) & 0x000000ff;
+ }
+}
+
+#endif
--- a/src/rfc1035.c
+++ b/src/rfc1035.c
@@ -333,55 +333,6 @@ unsigned char *skip_section(unsigned cha
return ansp;
}
-/* CRC the question section. This is used to safely detect query
- retransmission and to detect answers to questions we didn't ask, which
- might be poisoning attacks. Note that we decode the name rather
- than CRC the raw bytes, since replies might be compressed differently.
- We ignore case in the names for the same reason. Return all-ones
- if there is not question section. */
-#ifndef HAVE_DNSSEC
-unsigned int questions_crc(struct dns_header *header, size_t plen, char *name)
-{
- int q;
- unsigned int crc = 0xffffffff;
- unsigned char *p1, *p = (unsigned char *)(header+1);
-
- for (q = ntohs(header->qdcount); q != 0; q--)
- {
- if (!extract_name(header, plen, &p, name, 1, 4))
- return crc; /* bad packet */
-
- for (p1 = (unsigned char *)name; *p1; p1++)
- {
- int i = 8;
- char c = *p1;
-
- if (c >= 'A' && c <= 'Z')
- c += 'a' - 'A';
-
- crc ^= c << 24;
- while (i--)
- crc = crc & 0x80000000 ? (crc << 1) ^ 0x04c11db7 : crc << 1;
- }
-
- /* CRC the class and type as well */
- for (p1 = p; p1 < p+4; p1++)
- {
- int i = 8;
- crc ^= *p1 << 24;
- while (i--)
- crc = crc & 0x80000000 ? (crc << 1) ^ 0x04c11db7 : crc << 1;
- }
-
- p += 4;
- if (!CHECK_LEN(header, p, plen, 0))
- return crc; /* bad packet */
- }
-
- return crc;
-}
-#endif
-
size_t resize_packet(struct dns_header *header, size_t plen, unsigned char *pheader, size_t hlen)
{
unsigned char *ansp = skip_questions(header, plen);

122
package/network/services/dnsmasq/patches/0105-Optimse-RR-digest-calculation-in-DNSSEC.patch Normal file
View File

@ -0,0 +1,122 @@
From 059aded0700309308dafd9720b0313ce52f6e189 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Thu, 12 Nov 2020 23:09:15 +0000
Subject: Optimse RR digest calculation in DNSSEC.
If an RR is of a type which doesn't need canonicalisation,
bypass the relatively slow canonicalisation code, and insert
it direct into the digest.
---
src/dnssec.c | 82 +++++++++++++++++++++++++++++++---------------------
1 file changed, 49 insertions(+), 33 deletions(-)
--- a/src/dnssec.c
+++ b/src/dnssec.c
@@ -559,7 +559,7 @@ static int validate_rrset(time_t now, st
hash->update(ctx, (unsigned int)wire_len, (unsigned char*)keyname);
from_wire(keyname);
-#define RRBUFLEN 300 /* Most RRs are smaller than this. */
+#define RRBUFLEN 128 /* Most RRs are smaller than this. */
for (i = 0; i < rrsetidx; ++i)
{
@@ -597,50 +597,66 @@ static int validate_rrset(time_t now, st
hash->update(ctx, (unsigned int)wire_len, (unsigned char *)name_start);
hash->update(ctx, 4, p); /* class and type */
hash->update(ctx, 4, (unsigned char *)&nsigttl);
-
- p += 8; /* skip class, type, ttl */
+
+ p += 8; /* skip type, class, ttl */
GETSHORT(rdlen, p);
if (!CHECK_LEN(header, p, plen, rdlen))
return STAT_BOGUS;
-
- /* canonicalise rdata and calculate length of same, use
- name buffer as workspace for get_rdata. */
- state.ip = p;
- state.op = NULL;
- state.desc = rr_desc;
- state.buff = name;
- state.end = p + rdlen;
-
- for (j = 0; get_rdata(header, plen, &state); j++)
- if (j < RRBUFLEN)
- rrbuf[j] = *state.op;
- len = htons((u16)j);
- hash->update(ctx, 2, (unsigned char *)&len);
-
- /* If the RR is shorter than RRBUFLEN (most of them, in practice)
- then we can just digest it now. If it exceeds RRBUFLEN we have to
- go back to the start and do it in chunks. */
- if (j >= RRBUFLEN)
+ /* Optimisation for RR types which need no cannonicalisation.
+ This includes DNSKEY DS NSEC and NSEC3, which are also long, so
+ it saves lots of calls to get_rdata, and avoids the pessimal
+ segmented insertion, even with a small rrbuf[].
+
+ If canonicalisation is not needed, a simple insertion into the hash works.
+ */
+ if (*rr_desc == (u16)-1)
+ {
+ len = htons(rdlen);
+ hash->update(ctx, 2, (unsigned char *)&len);
+ hash->update(ctx, rdlen, p);
+ }
+ else
{
+ /* canonicalise rdata and calculate length of same, use
+ name buffer as workspace for get_rdata. */
state.ip = p;
state.op = NULL;
state.desc = rr_desc;
-
+ state.buff = name;
+ state.end = p + rdlen;
+
for (j = 0; get_rdata(header, plen, &state); j++)
+ if (j < RRBUFLEN)
+ rrbuf[j] = *state.op;
+
+ len = htons((u16)j);
+ hash->update(ctx, 2, (unsigned char *)&len);
+
+ /* If the RR is shorter than RRBUFLEN (most of them, in practice)
+ then we can just digest it now. If it exceeds RRBUFLEN we have to
+ go back to the start and do it in chunks. */
+ if (j >= RRBUFLEN)
{
- rrbuf[j] = *state.op;
-
- if (j == RRBUFLEN - 1)
- {
- hash->update(ctx, RRBUFLEN, rrbuf);
- j = -1;
- }
+ state.ip = p;
+ state.op = NULL;
+ state.desc = rr_desc;
+
+ for (j = 0; get_rdata(header, plen, &state); j++)
+ {
+ rrbuf[j] = *state.op;
+
+ if (j == RRBUFLEN - 1)
+ {
+ hash->update(ctx, RRBUFLEN, rrbuf);
+ j = -1;
+ }
+ }
}
+
+ if (j != 0)
+ hash->update(ctx, j, rrbuf);
}
-
- if (j != 0)
- hash->update(ctx, j, rrbuf);
}
hash->digest(ctx, hash->digest_size, digest);

64
package/network/services/dnsmasq/patches/0107-Add-missing-check-for-NULL-return-from-allocate_rfd.patch Normal file
View File

@ -0,0 +1,64 @@
From 824461192ca5098043f9ca4ddeba7df1f65b30ba Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Sun, 15 Nov 2020 22:13:25 +0000
Subject: Add missing check for NULL return from allocate_rfd().
---
src/forward.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
--- a/src/forward.c
+++ b/src/forward.c
@@ -815,7 +815,6 @@ void reply_query(int fd, int family, tim
int is_sign;
#ifdef HAVE_DNSSEC
- /* For DNSSEC originated queries, just retry the query to the same server. */
if (forward->flags & (FREC_DNSKEY_QUERY | FREC_DS_QUERY))
{
struct server *start;
@@ -841,6 +840,8 @@ void reply_query(int fd, int family, tim
}
+ fd = -1;
+
if (start->sfd)
fd = start->sfd->fd;
else
@@ -848,19 +849,21 @@ void reply_query(int fd, int family, tim
if (start->addr.sa.sa_family == AF_INET6)
{
/* may have changed family */
- if (!forward->rfd6)
- forward->rfd6 = allocate_rfd(AF_INET6);
- fd = forward->rfd6->fd;
+ if (forward->rfd6 || (forward->rfd6 = allocate_rfd(AF_INET6)))
+ fd = forward->rfd6->fd;
}
else
{
/* may have changed family */
- if (!forward->rfd4)
- forward->rfd4 = allocate_rfd(AF_INET);
- fd = forward->rfd4->fd;
+ if (forward->rfd4 || (forward->rfd4 = allocate_rfd(AF_INET)))
+ fd = forward->rfd4->fd;
}
}
+ /* Can't get socket. */
+ if (fd == -1)
+ return;
+
while (retry_send(sendto(fd, (char *)header, plen, 0,
&start->addr.sa,
sa_len(&start->addr))));
@@ -2261,7 +2264,6 @@ struct frec *get_new_frec(time_t now, in
return f; /* OK if malloc fails and this is NULL */
}
-/* crc is all-ones if not known. */
static struct frec *lookup_frec(unsigned short id, int fd, int family, void *hash)
{
struct frec *f;

352
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@ -0,0 +1,352 @@
From 15b60ddf935a531269bb8c68198de012a4967156 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Wed, 18 Nov 2020 18:34:55 +0000
Subject: Handle multiple identical near simultaneous DNS queries better.
Previously, such queries would all be forwarded
independently. This is, in theory, inefficent but in practise
not a problem, _except_ that is means that an answer for any
of the forwarded queries will be accepted and cached.
An attacker can send a query multiple times, and for each repeat,
another {port, ID} becomes capable of accepting the answer he is
sending in the blind, to random IDs and ports. The chance of a
succesful attack is therefore multiplied by the number of repeats
of the query. The new behaviour detects repeated queries and
merely stores the clients sending repeats so that when the
first query completes, the answer can be sent to all the
clients who asked. Refer: CERT VU#434904.
---
CHANGELOG | 16 +++++-
src/dnsmasq.h | 19 ++++---
src/forward.c | 142 ++++++++++++++++++++++++++++++++++++++++++--------
3 files changed, 147 insertions(+), 30 deletions(-)
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -4,13 +4,27 @@
Be sure to only accept UDP DNS query replies at the address
from which the query was originated. This keeps as much entropy
- in the {query-ID, random-port} tuple as possible, help defeat
+ in the {query-ID, random-port} tuple as possible, to help defeat
cache poisoning attacks. Refer: CERT VU#434904.
Use the SHA-256 hash function to verify that DNS answers
received are for the questions originally asked. This replaces
the slightly insecure SHA-1 (when compiled with DNSSEC) or
the very insecure CRC32 (otherwise). Refer: CERT VU#434904.
+
+ Handle multiple identical near simultaneous DNS queries better.
+ Previously, such queries would all be forwarded
+ independently. This is, in theory, inefficent but in practise
+ not a problem, _except_ that is means that an answer for any
+ of the forwarded queries will be accepted and cached.
+ An attacker can send a query multiple times, and for each repeat,
+ another {port, ID} becomes capable of accepting the answer he is
+ sending in the blind, to random IDs and ports. The chance of a
+ succesful attack is therefore multiplied by the number of repeats
+ of the query. The new behaviour detects repeated queries and
+ merely stores the clients sending repeats so that when the
+ first query completes, the answer can be sent to all the
+ clients who asked. Refer: CERT VU#434904.
version 2.81
--- a/src/dnsmasq.h
+++ b/src/dnsmasq.h
@@ -642,19 +642,24 @@ struct hostsfile {
#define FREC_DO_QUESTION 64
#define FREC_ADDED_PHEADER 128
#define FREC_TEST_PKTSZ 256
-#define FREC_HAS_EXTRADATA 512
+#define FREC_HAS_EXTRADATA 512
+#define FREC_HAS_PHEADER 1024
#define HASH_SIZE 32 /* SHA-256 digest size */
struct frec {
- union mysockaddr source;
- union all_addr dest;
+ struct frec_src {
+ union mysockaddr source;
+ union all_addr dest;
+ unsigned int iface, log_id;
+ unsigned short orig_id;
+ struct frec_src *next;
+ } frec_src;
struct server *sentto; /* NULL means free */
struct randfd *rfd4;
struct randfd *rfd6;
- unsigned int iface;
- unsigned short orig_id, new_id;
- int log_id, fd, forwardall, flags;
+ unsigned short new_id;
+ int fd, forwardall, flags;
time_t time;
unsigned char *hash[HASH_SIZE];
#ifdef HAVE_DNSSEC
@@ -1069,6 +1074,8 @@ extern struct daemon {
int back_to_the_future;
#endif
struct frec *frec_list;
+ struct frec_src *free_frec_src;
+ int frec_src_count;
struct serverfd *sfds;
struct irec *interfaces;
struct listener *listeners;
--- a/src/forward.c
+++ b/src/forward.c
@@ -20,6 +20,8 @@ static struct frec *lookup_frec(unsigned
static struct frec *lookup_frec_by_sender(unsigned short id,
union mysockaddr *addr,
void *hash);
+static struct frec *lookup_frec_by_query(void *hash, unsigned int flags);
+
static unsigned short get_id(void);
static void free_frec(struct frec *f);
@@ -247,6 +249,7 @@ static int forward_query(int udpfd, unio
int type = SERV_DO_DNSSEC, norebind = 0;
union all_addr *addrp = NULL;
unsigned int flags = 0;
+ unsigned int fwd_flags = 0;
struct server *start = NULL;
void *hash = hash_questions(header, plen, daemon->namebuff);
#ifdef HAVE_DNSSEC
@@ -255,7 +258,18 @@ static int forward_query(int udpfd, unio
unsigned int gotname = extract_request(header, plen, daemon->namebuff, NULL);
unsigned char *oph = find_pseudoheader(header, plen, NULL, NULL, NULL, NULL);
(void)do_bit;
-
+
+ if (header->hb4 & HB4_CD)
+ fwd_flags |= FREC_CHECKING_DISABLED;
+ if (ad_reqd)
+ fwd_flags |= FREC_AD_QUESTION;
+ if (oph)
+ fwd_flags |= FREC_HAS_PHEADER;
+#ifdef HAVE_DNSSEC
+ if (do_bit)
+ fwd_flags |= FREC_DO_QUESTION;
+#endif
+
/* may be no servers available. */
if (forward || (forward = lookup_frec_by_sender(ntohs(header->id), udpaddr, hash)))
{
@@ -328,6 +342,39 @@ static int forward_query(int udpfd, unio
}
else
{
+ /* Query from new source, but the same query may be in progress
+ from another source. If so, just add this client to the
+ list that will get the reply.
+
+ Note that is the EDNS client subnet option is in use, we can't do this,
+ as the clients (and therefore query EDNS options) will be different
+ for each query. The EDNS subnet code has checks to avoid
+ attacks in this case. */
+ if (!option_bool(OPT_CLIENT_SUBNET) && (forward = lookup_frec_by_query(hash, fwd_flags)))
+ {
+ /* Note whine_malloc() zeros memory. */
+ if (!daemon->free_frec_src &&
+ daemon->frec_src_count < daemon->ftabsize &&
+ (daemon->free_frec_src = whine_malloc(sizeof(struct frec_src))))
+ daemon->frec_src_count++;
+
+ /* If we've been spammed with many duplicates, just drop the query. */
+ if (daemon->free_frec_src)
+ {
+ struct frec_src *new = daemon->free_frec_src;
+ daemon->free_frec_src = new->next;
+ new->next = forward->frec_src.next;
+ forward->frec_src.next = new;
+ new->orig_id = ntohs(header->id);
+ new->source = *udpaddr;
+ new->dest = *dst_addr;
+ new->log_id = daemon->log_id;
+ new->iface = dst_iface;
+ }
+
+ return 1;
+ }
+
if (gotname)
flags = search_servers(now, &addrp, gotname, daemon->namebuff, &type, &domain, &norebind);
@@ -335,22 +382,22 @@ static int forward_query(int udpfd, unio
do_dnssec = type & SERV_DO_DNSSEC;
#endif
type &= ~SERV_DO_DNSSEC;
-
+
if (daemon->servers && !flags)
forward = get_new_frec(now, NULL, 0);
/* table full - flags == 0, return REFUSED */
if (forward)
{
- forward->source = *udpaddr;
- forward->dest = *dst_addr;
- forward->iface = dst_iface;
- forward->orig_id = ntohs(header->id);
+ forward->frec_src.source = *udpaddr;
+ forward->frec_src.orig_id = ntohs(header->id);
+ forward->frec_src.dest = *dst_addr;
+ forward->frec_src.iface = dst_iface;
forward->new_id = get_id();
forward->fd = udpfd;
memcpy(forward->hash, hash, HASH_SIZE);
forward->forwardall = 0;
- forward->flags = 0;
+ forward->flags = fwd_flags;
if (norebind)
forward->flags |= FREC_NOREBIND;
if (header->hb4 & HB4_CD)
@@ -405,9 +452,9 @@ static int forward_query(int udpfd, unio
unsigned char *pheader;
/* If a query is retried, use the log_id for the retry when logging the answer. */
- forward->log_id = daemon->log_id;
+ forward->frec_src.log_id = daemon->log_id;
- plen = add_edns0_config(header, plen, ((unsigned char *)header) + PACKETSZ, &forward->source, now, &subnet);
+ plen = add_edns0_config(header, plen, ((unsigned char *)header) + PACKETSZ, &forward->frec_src.source, now, &subnet);
if (subnet)
forward->flags |= FREC_HAS_SUBNET;
@@ -544,7 +591,7 @@ static int forward_query(int udpfd, unio
return 1;
/* could not send on, prepare to return */
- header->id = htons(forward->orig_id);
+ header->id = htons(forward->frec_src.orig_id);
free_frec(forward); /* cancel */
}
@@ -796,8 +843,8 @@ void reply_query(int fd, int family, tim
/* log_query gets called indirectly all over the place, so
pass these in global variables - sorry. */
- daemon->log_display_id = forward->log_id;
- daemon->log_source_addr = &forward->source;
+ daemon->log_display_id = forward->frec_src.log_id;
+ daemon->log_source_addr = &forward->frec_src.source;
if (daemon->ignore_addr && RCODE(header) == NOERROR &&
check_for_ignored_address(header, n, daemon->ignore_addr))
@@ -1065,6 +1112,7 @@ void reply_query(int fd, int family, tim
new->sentto = server;
new->rfd4 = NULL;
new->rfd6 = NULL;
+ new->frec_src.next = NULL;
new->flags &= ~(FREC_DNSKEY_QUERY | FREC_DS_QUERY | FREC_HAS_EXTRADATA);
new->forwardall = 0;
@@ -1199,9 +1247,11 @@ void reply_query(int fd, int family, tim
if ((nn = process_reply(header, now, forward->sentto, (size_t)n, check_rebind, no_cache_dnssec, cache_secure, bogusanswer,
forward->flags & FREC_AD_QUESTION, forward->flags & FREC_DO_QUESTION,
- forward->flags & FREC_ADDED_PHEADER, forward->flags & FREC_HAS_SUBNET, &forward->source)))
+ forward->flags & FREC_ADDED_PHEADER, forward->flags & FREC_HAS_SUBNET, &forward->frec_src.source)))
{
- header->id = htons(forward->orig_id);
+ struct frec_src *src;
+
+ header->id = htons(forward->frec_src.orig_id);
header->hb4 |= HB4_RA; /* recursion if available */
#ifdef HAVE_DNSSEC
/* We added an EDNSO header for the purpose of getting DNSSEC RRs, and set the value of the UDP payload size
@@ -1217,13 +1267,26 @@ void reply_query(int fd, int family, tim
}
#endif
+ for (src = &forward->frec_src; src; src = src->next)
+ {
+ header->id = htons(src->orig_id);
+
#ifdef HAVE_DUMPFILE
- dump_packet(DUMP_REPLY, daemon->packet, (size_t)nn, NULL, &forward->source);
+ dump_packet(DUMP_REPLY, daemon->packet, (size_t)nn, NULL, &src->source);
#endif
-
- send_from(forward->fd, option_bool(OPT_NOWILD) || option_bool (OPT_CLEVERBIND), daemon->packet, nn,
- &forward->source, &forward->dest, forward->iface);
+
+ send_from(forward->fd, option_bool(OPT_NOWILD) || option_bool (OPT_CLEVERBIND), daemon->packet, nn,
+ &src->source, &src->dest, src->iface);
+
+ if (option_bool(OPT_EXTRALOG) && src != &forward->frec_src)
+ {
+ daemon->log_display_id = src->log_id;
+ daemon->log_source_addr = &src->source;
+ log_query(F_UPSTREAM, "query", NULL, "duplicate");
+ }
+ }
}
+
free_frec(forward); /* cancel */
}
}
@@ -2153,6 +2216,17 @@ void free_rfd(struct randfd *rfd)
static void free_frec(struct frec *f)
{
+ struct frec_src *src, *tmp;
+
+ /* add back to freelist of not the record builtin to every frec. */
+ for (src = f->frec_src.next; src; src = tmp)
+ {
+ tmp = src->next;
+ src->next = daemon->free_frec_src;
+ daemon->free_frec_src = src;
+ }
+
+ f->frec_src.next = NULL;
free_rfd(f->rfd4);
f->rfd4 = NULL;
f->sentto = NULL;
@@ -2292,17 +2366,39 @@ static struct frec *lookup_frec_by_sende
void *hash)
{
struct frec *f;
+ struct frec_src *src;
+
+ for (f = daemon->frec_list; f; f = f->next)
+ if (f->sentto &&
+ !(f->flags & (FREC_DNSKEY_QUERY | FREC_DS_QUERY)) &&
+ memcmp(hash, f->hash, HASH_SIZE) == 0)
+ for (src = &f->frec_src; src; src = src->next)
+ if (src->orig_id == id &&
+ sockaddr_isequal(&src->source, addr))
+ return f;
+
+ return NULL;
+}
+
+static struct frec *lookup_frec_by_query(void *hash, unsigned int flags)
+{
+ struct frec *f;
+
+ /* FREC_DNSKEY and FREC_DS_QUERY are never set in flags, so the test below
+ ensures that no frec created for internal DNSSEC query can be returned here. */
+
+#define FLAGMASK (FREC_CHECKING_DISABLED | FREC_AD_QUESTION | FREC_DO_QUESTION \
+ | FREC_HAS_PHEADER | FREC_DNSKEY_QUERY | FREC_DS_QUERY)
for(f = daemon->frec_list; f; f = f->next)
if (f->sentto &&
- f->orig_id == id &&
- memcmp(hash, f->hash, HASH_SIZE) == 0 &&
- sockaddr_isequal(&f->source, addr))
+ (f->flags & FLAGMASK) == flags &&
+ memcmp(hash, f->hash, HASH_SIZE) == 0)
return f;
-
+
return NULL;
}
-
+
/* Send query packet again, if we can. */
void resend_query()
{

350
package/network/services/dnsmasq/patches/0109-Handle-caching-with-EDNS-options-better.patch Normal file
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@ -0,0 +1,350 @@
From 25e63f1e56f5acdcf91893a1b92ad1e0f2f552d8 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Wed, 25 Nov 2020 21:17:52 +0000
Subject: Handle caching with EDNS options better.
If we add the EDNS client subnet option, or the client's
MAC address, then the reply we get back may very depending on
that. Since the cache is ignorant of such things, it's not safe to
cache such replies. This patch determines when a dangerous EDNS
option is being added and disables caching.
Note that for much the same reason, we can't combine multiple
queries for the same question when dangerous EDNS options are
being added, and the code now handles that in the same way. This
query combining is required for security against cache poisoning,
so disabling the cache has a security function as well as a
correctness one.
---
man/dnsmasq.8 | 4 +--
src/dnsmasq.h | 3 ++-
src/edns0.c | 75 ++++++++++++++++++++++++++++++++-------------------
src/forward.c | 41 ++++++++++++++++++----------
4 files changed, 78 insertions(+), 45 deletions(-)
--- a/man/dnsmasq.8
+++ b/man/dnsmasq.8
@@ -690,8 +690,8 @@ still marks the request so that no upstr
address information either. The default is zero for both IPv4 and
IPv6. Note that upstream nameservers may be configured to return
different results based on this information, but the dnsmasq cache
-does not take account. If a dnsmasq instance is configured such that
-different results may be encountered, caching should be disabled.
+does not take account. Caching is therefore disabled for such replies,
+unless the subnet address being added is constant.
For example,
.B --add-subnet=24,96
--- a/src/dnsmasq.h
+++ b/src/dnsmasq.h
@@ -644,6 +644,7 @@ struct hostsfile {
#define FREC_TEST_PKTSZ 256
#define FREC_HAS_EXTRADATA 512
#define FREC_HAS_PHEADER 1024
+#define FREC_NO_CACHE 2048
#define HASH_SIZE 32 /* SHA-256 digest size */
@@ -1628,7 +1629,7 @@ size_t add_pseudoheader(struct dns_heade
unsigned short udp_sz, int optno, unsigned char *opt, size_t optlen, int set_do, int replace);
size_t add_do_bit(struct dns_header *header, size_t plen, unsigned char *limit);
size_t add_edns0_config(struct dns_header *header, size_t plen, unsigned char *limit,
- union mysockaddr *source, time_t now, int *check_subnet);
+ union mysockaddr *source, time_t now, int *check_subnet, int *cacheable);
int check_source(struct dns_header *header, size_t plen, unsigned char *pseudoheader, union mysockaddr *peer);
/* arp.c */
--- a/src/edns0.c
+++ b/src/edns0.c
@@ -264,7 +264,8 @@ static void encoder(unsigned char *in, c
out[3] = char64(in[2]);
}
-static size_t add_dns_client(struct dns_header *header, size_t plen, unsigned char *limit, union mysockaddr *l3, time_t now)
+static size_t add_dns_client(struct dns_header *header, size_t plen, unsigned char *limit,
+ union mysockaddr *l3, time_t now, int *cacheablep)
{
int maclen, replace = 2; /* can't get mac address, just delete any incoming. */
unsigned char mac[DHCP_CHADDR_MAX];
@@ -273,6 +274,7 @@ static size_t add_dns_client(struct dns_
if ((maclen = find_mac(l3, mac, 1, now)) == 6)
{
replace = 1;
+ *cacheablep = 0;
if (option_bool(OPT_MAC_HEX))
print_mac(encode, mac, maclen);
@@ -288,14 +290,18 @@ static size_t add_dns_client(struct dns_
}
-static size_t add_mac(struct dns_header *header, size_t plen, unsigned char *limit, union mysockaddr *l3, time_t now)
+static size_t add_mac(struct dns_header *header, size_t plen, unsigned char *limit,
+ union mysockaddr *l3, time_t now, int *cacheablep)
{
int maclen;
unsigned char mac[DHCP_CHADDR_MAX];
if ((maclen = find_mac(l3, mac, 1, now)) != 0)
- plen = add_pseudoheader(header, plen, limit, PACKETSZ, EDNS0_OPTION_MAC, mac, maclen, 0, 0);
-
+ {
+ *cacheablep = 0;
+ plen = add_pseudoheader(header, plen, limit, PACKETSZ, EDNS0_OPTION_MAC, mac, maclen, 0, 0);
+ }
+
return plen;
}
@@ -313,17 +319,18 @@ static void *get_addrp(union mysockaddr
return &addr->in.sin_addr;
}
-static size_t calc_subnet_opt(struct subnet_opt *opt, union mysockaddr *source)
+static size_t calc_subnet_opt(struct subnet_opt *opt, union mysockaddr *source, int *cacheablep)
{
/* http://tools.ietf.org/html/draft-vandergaast-edns-client-subnet-02 */
int len;
void *addrp = NULL;
int sa_family = source->sa.sa_family;
-
+ int cacheable = 0;
+
opt->source_netmask = 0;
opt->scope_netmask = 0;
-
+
if (source->sa.sa_family == AF_INET6 && daemon->add_subnet6)
{
opt->source_netmask = daemon->add_subnet6->mask;
@@ -331,6 +338,7 @@ static size_t calc_subnet_opt(struct sub
{
sa_family = daemon->add_subnet6->addr.sa.sa_family;
addrp = get_addrp(&daemon->add_subnet6->addr, sa_family);
+ cacheable = 1;
}
else
addrp = &source->in6.sin6_addr;
@@ -343,6 +351,7 @@ static size_t calc_subnet_opt(struct sub
{
sa_family = daemon->add_subnet4->addr.sa.sa_family;
addrp = get_addrp(&daemon->add_subnet4->addr, sa_family);
+ cacheable = 1; /* Address is constant */
}
else
addrp = &source->in.sin_addr;
@@ -350,8 +359,6 @@ static size_t calc_subnet_opt(struct sub
opt->family = htons(sa_family == AF_INET6 ? 2 : 1);
- len = 0;
-
if (addrp && opt->source_netmask != 0)
{
len = ((opt->source_netmask - 1) >> 3) + 1;
@@ -359,18 +366,26 @@ static size_t calc_subnet_opt(struct sub
if (opt->source_netmask & 7)
opt->addr[len-1] &= 0xff << (8 - (opt->source_netmask & 7));
}
+ else
+ {
+ cacheable = 1; /* No address ever supplied. */
+ len = 0;
+ }
+
+ if (cacheablep)
+ *cacheablep = cacheable;
return len + 4;
}
-static size_t add_source_addr(struct dns_header *header, size_t plen, unsigned char *limit, union mysockaddr *source)
+static size_t add_source_addr(struct dns_header *header, size_t plen, unsigned char *limit, union mysockaddr *source, int *cacheable)
{
/* http://tools.ietf.org/html/draft-vandergaast-edns-client-subnet-02 */
int len;
struct subnet_opt opt;
- len = calc_subnet_opt(&opt, source);
+ len = calc_subnet_opt(&opt, source, cacheable);
return add_pseudoheader(header, plen, (unsigned char *)limit, PACKETSZ, EDNS0_OPTION_CLIENT_SUBNET, (unsigned char *)&opt, len, 0, 0);
}
@@ -383,18 +398,18 @@ int check_source(struct dns_header *head
unsigned char *p;
int code, i, rdlen;
- calc_len = calc_subnet_opt(&opt, peer);
-
- if (!(p = skip_name(pseudoheader, header, plen, 10)))
- return 1;
-
- p += 8; /* skip UDP length and RCODE */
+ calc_len = calc_subnet_opt(&opt, peer, NULL);
- GETSHORT(rdlen, p);
- if (!CHECK_LEN(header, p, plen, rdlen))
- return 1; /* bad packet */
-
- /* check if option there */
+ if (!(p = skip_name(pseudoheader, header, plen, 10)))
+ return 1;
+
+ p += 8; /* skip UDP length and RCODE */
+
+ GETSHORT(rdlen, p);
+ if (!CHECK_LEN(header, p, plen, rdlen))
+ return 1; /* bad packet */
+
+ /* check if option there */
for (i = 0; i + 4 < rdlen; i += len + 4)
{
GETSHORT(code, p);
@@ -412,24 +427,28 @@ int check_source(struct dns_header *head
return 1;
}
+/* Set *check_subnet if we add a client subnet option, which needs to checked
+ in the reply. Set *cacheable to zero if we add an option which the answer
+ may depend on. */
size_t add_edns0_config(struct dns_header *header, size_t plen, unsigned char *limit,
- union mysockaddr *source, time_t now, int *check_subnet)
+ union mysockaddr *source, time_t now, int *check_subnet, int *cacheable)
{
*check_subnet = 0;
-
+ *cacheable = 1;
+
if (option_bool(OPT_ADD_MAC))
- plen = add_mac(header, plen, limit, source, now);
+ plen = add_mac(header, plen, limit, source, now, cacheable);
if (option_bool(OPT_MAC_B64) || option_bool(OPT_MAC_HEX))
- plen = add_dns_client(header, plen, limit, source, now);
-
+ plen = add_dns_client(header, plen, limit, source, now, cacheable);
+
if (daemon->dns_client_id)
plen = add_pseudoheader(header, plen, limit, PACKETSZ, EDNS0_OPTION_NOMCPEID,
(unsigned char *)daemon->dns_client_id, strlen(daemon->dns_client_id), 0, 1);
if (option_bool(OPT_CLIENT_SUBNET))
{
- plen = add_source_addr(header, plen, limit, source);
+ plen = add_source_addr(header, plen, limit, source, cacheable);
*check_subnet = 1;
}
--- a/src/forward.c
+++ b/src/forward.c
@@ -344,13 +344,10 @@ static int forward_query(int udpfd, unio
{
/* Query from new source, but the same query may be in progress
from another source. If so, just add this client to the
- list that will get the reply.
+ list that will get the reply.*/
- Note that is the EDNS client subnet option is in use, we can't do this,
- as the clients (and therefore query EDNS options) will be different
- for each query. The EDNS subnet code has checks to avoid
- attacks in this case. */
- if (!option_bool(OPT_CLIENT_SUBNET) && (forward = lookup_frec_by_query(hash, fwd_flags)))
+ if (!option_bool(OPT_ADD_MAC) && !option_bool(OPT_MAC_B64) &&
+ (forward = lookup_frec_by_query(hash, fwd_flags)))
{
/* Note whine_malloc() zeros memory. */
if (!daemon->free_frec_src &&
@@ -447,18 +444,21 @@ static int forward_query(int udpfd, unio
if (!flags && forward)
{
struct server *firstsentto = start;
- int subnet, forwarded = 0;
+ int subnet, cacheable, forwarded = 0;
size_t edns0_len;
unsigned char *pheader;
/* If a query is retried, use the log_id for the retry when logging the answer. */
forward->frec_src.log_id = daemon->log_id;
- plen = add_edns0_config(header, plen, ((unsigned char *)header) + PACKETSZ, &forward->frec_src.source, now, &subnet);
+ plen = add_edns0_config(header, plen, ((unsigned char *)header) + PACKETSZ, &forward->frec_src.source, now, &subnet, &cacheable);
if (subnet)
forward->flags |= FREC_HAS_SUBNET;
-
+
+ if (!cacheable)
+ forward->flags |= FREC_NO_CACHE;
+
#ifdef HAVE_DNSSEC
if (option_bool(OPT_DNSSEC_VALID) && do_dnssec)
{
@@ -642,7 +642,7 @@ static size_t process_reply(struct dns_h
}
}
#endif
-
+
if ((pheader = find_pseudoheader(header, n, &plen, &sizep, &is_sign, NULL)))
{
/* Get extended RCODE. */
@@ -1244,6 +1244,11 @@ void reply_query(int fd, int family, tim
header->hb4 |= HB4_CD;
else
header->hb4 &= ~HB4_CD;
+
+ /* Never cache answers which are contingent on the source or MAC address EDSN0 option,
+ since the cache is ignorant of such things. */
+ if (forward->flags & FREC_NO_CACHE)
+ no_cache_dnssec = 1;
if ((nn = process_reply(header, now, forward->sentto, (size_t)n, check_rebind, no_cache_dnssec, cache_secure, bogusanswer,
forward->flags & FREC_AD_QUESTION, forward->flags & FREC_DO_QUESTION,
@@ -1788,7 +1793,7 @@ unsigned char *tcp_request(int confd, ti
int local_auth = 0;
#endif
int checking_disabled, do_bit, added_pheader = 0, have_pseudoheader = 0;
- int check_subnet, no_cache_dnssec = 0, cache_secure = 0, bogusanswer = 0;
+ int check_subnet, cacheable, no_cache_dnssec = 0, cache_secure = 0, bogusanswer = 0;
size_t m;
unsigned short qtype;
unsigned int gotname;
@@ -1959,7 +1964,7 @@ unsigned char *tcp_request(int confd, ti
char *domain = NULL;
unsigned char *oph = find_pseudoheader(header, size, NULL, NULL, NULL, NULL);
- size = add_edns0_config(header, size, ((unsigned char *) header) + 65536, &peer_addr, now, &check_subnet);
+ size = add_edns0_config(header, size, ((unsigned char *) header) + 65536, &peer_addr, now, &check_subnet, &cacheable);
if (gotname)
flags = search_servers(now, &addrp, gotname, daemon->namebuff, &type, &domain, &norebind);
@@ -2122,6 +2127,11 @@ unsigned char *tcp_request(int confd, ti
break;
}
+ /* Never cache answers which are contingent on the source or MAC address EDSN0 option,
+ since the cache is ignorant of such things. */
+ if (!cacheable)
+ no_cache_dnssec = 1;
+
m = process_reply(header, now, last_server, (unsigned int)m,
option_bool(OPT_NO_REBIND) && !norebind, no_cache_dnssec, cache_secure, bogusanswer,
ad_reqd, do_bit, added_pheader, check_subnet, &peer_addr);
@@ -2385,10 +2395,13 @@ static struct frec *lookup_frec_by_query
struct frec *f;
/* FREC_DNSKEY and FREC_DS_QUERY are never set in flags, so the test below
- ensures that no frec created for internal DNSSEC query can be returned here. */
+ ensures that no frec created for internal DNSSEC query can be returned here.
+
+ Similarly FREC_NO_CACHE is never set in flags, so a query which is
+ contigent on a particular source address EDNS0 option will never be matched. */
#define FLAGMASK (FREC_CHECKING_DISABLED | FREC_AD_QUESTION | FREC_DO_QUESTION \
- | FREC_HAS_PHEADER | FREC_DNSKEY_QUERY | FREC_DS_QUERY)
+ | FREC_HAS_PHEADER | FREC_DNSKEY_QUERY | FREC_DS_QUERY | FREC_NO_CACHE)
for(f = daemon->frec_list; f; f = f->next)
if (f->sentto &&

181
package/network/services/dnsmasq/patches/0110-Support-hash-function-from-nettle-only.patch Normal file
View File

@ -0,0 +1,181 @@
From 2024f9729713fd657d65e64c2e4e471baa0a3e5b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20Men=C5=A1=C3=ADk?= <pemensik@redhat.com>
Date: Wed, 25 Nov 2020 17:18:55 +0100
Subject: Support hash function from nettle (only)
Unlike COPTS=-DHAVE_DNSSEC, allow usage of just sha256 function from
nettle, but keep DNSSEC disabled at build time. Skips use of internal
hash implementation without support for validation built-in.
---
Makefile | 8 +++++---
bld/pkg-wrapper | 41 ++++++++++++++++++++++-------------------
src/config.h | 8 ++++++++
src/crypto.c | 7 +++++++
src/dnsmasq.h | 2 +-
src/hash_questions.c | 2 +-
6 files changed, 44 insertions(+), 24 deletions(-)
--- a/Makefile
+++ b/Makefile
@@ -53,7 +53,7 @@ top?=$(CURDIR)
dbus_cflags = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_DBUS $(PKG_CONFIG) --cflags dbus-1`
dbus_libs = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_DBUS $(PKG_CONFIG) --libs dbus-1`
-ubus_libs = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_UBUS "" --copy -lubox -lubus`
+ubus_libs = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_UBUS "" --copy '-lubox -lubus'`
idn_cflags = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_IDN $(PKG_CONFIG) --cflags libidn`
idn_libs = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_IDN $(PKG_CONFIG) --libs libidn`
idn2_cflags = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_LIBIDN2 $(PKG_CONFIG) --cflags libidn2`
@@ -62,8 +62,10 @@ ct_cflags = `echo $(COPTS) | $(top)/
ct_libs = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_CONNTRACK $(PKG_CONFIG) --libs libnetfilter_conntrack`
lua_cflags = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_LUASCRIPT $(PKG_CONFIG) --cflags lua5.2`
lua_libs = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_LUASCRIPT $(PKG_CONFIG) --libs lua5.2`
-nettle_cflags = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_DNSSEC $(PKG_CONFIG) --cflags nettle hogweed`
-nettle_libs = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_DNSSEC $(PKG_CONFIG) --libs nettle hogweed`
+nettle_cflags = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_DNSSEC $(PKG_CONFIG) --cflags 'nettle hogweed' \
+ HAVE_NETTLEHASH $(PKG_CONFIG) --cflags nettle`
+nettle_libs = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_DNSSEC $(PKG_CONFIG) --libs 'nettle hogweed' \
+ HAVE_NETTLEHASH $(PKG_CONFIG) --libs nettle`
gmp_libs = `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_DNSSEC NO_GMP --copy -lgmp`
sunos_libs = `if uname | grep SunOS >/dev/null 2>&1; then echo -lsocket -lnsl -lposix4; fi`
version = -DVERSION='\"`$(top)/bld/get-version $(top)`\"'
--- a/bld/pkg-wrapper
+++ b/bld/pkg-wrapper
@@ -1,35 +1,37 @@
#!/bin/sh
-search=$1
-shift
-pkg=$1
-shift
-op=$1
-shift
-
in=`cat`
-if grep "^\#[[:space:]]*define[[:space:]]*$search" config.h >/dev/null 2>&1 || \
- echo $in | grep $search >/dev/null 2>&1; then
+search()
+{
+ grep "^\#[[:space:]]*define[[:space:]]*$1" config.h >/dev/null 2>&1 || \
+ echo $in | grep $1 >/dev/null 2>&1
+}
+
+while [ "$#" -gt 0 ]; do
+ search=$1
+ pkg=$2
+ op=$3
+ lib=$4
+ shift 4
+if search "$search"; then
+
# Nasty, nasty, in --copy, arg 2 (if non-empty) is another config to search for, used with NO_GMP
if [ $op = "--copy" ]; then
if [ -z "$pkg" ]; then
- pkg="$*"
- elif grep "^\#[[:space:]]*define[[:space:]]*$pkg" config.h >/dev/null 2>&1 || \
- echo $in | grep $pkg >/dev/null 2>&1; then
+ pkg="$lib"
+ elif search "$pkg"; then
pkg=""
else
- pkg="$*"
+ pkg="$lib"
fi
- elif grep "^\#[[:space:]]*define[[:space:]]*${search}_STATIC" config.h >/dev/null 2>&1 || \
- echo $in | grep ${search}_STATIC >/dev/null 2>&1; then
- pkg=`$pkg --static $op $*`
+ elif search "${search}_STATIC"; then
+ pkg=`$pkg --static $op $lib`
else
- pkg=`$pkg $op $*`
+ pkg=`$pkg $op $lib`
fi
- if grep "^\#[[:space:]]*define[[:space:]]*${search}_STATIC" config.h >/dev/null 2>&1 || \
- echo $in | grep ${search}_STATIC >/dev/null 2>&1; then
+ if search "${search}_STATIC"; then
if [ $op = "--libs" ] || [ $op = "--copy" ]; then
echo "-Wl,-Bstatic $pkg -Wl,-Bdynamic"
else
@@ -40,3 +42,4 @@ if grep "^\#[[:space:]]*define[[:space:]
fi
fi
+done
--- a/src/config.h
+++ b/src/config.h
@@ -117,6 +117,9 @@ HAVE_AUTH
define this to include the facility to act as an authoritative DNS
server for one or more zones.
+HAVE_NETTLEHASH
+ include just hash function from nettle, but no DNSSEC.
+
HAVE_DNSSEC
include DNSSEC validator.
@@ -184,6 +187,7 @@ RESOLVFILE
/* #define HAVE_IDN */
/* #define HAVE_LIBIDN2 */
/* #define HAVE_CONNTRACK */
+/* #define HAVE_NETTLEHASH */
/* #define HAVE_DNSSEC */
@@ -408,6 +412,10 @@ static char *compile_opts =
"no-"
#endif
"auth "
+#if !defined(HAVE_NETTLEHASH) && !defined(HAVE_DNSSEC)
+"no-"
+#endif
+"nettlehash "
#ifndef HAVE_DNSSEC
"no-"
#endif
--- a/src/crypto.c
+++ b/src/crypto.c
@@ -23,6 +23,9 @@
#include <nettle/ecdsa.h>
#include <nettle/ecc-curve.h>
#include <nettle/eddsa.h>
+#endif
+
+#if defined(HAVE_DNSSEC) || defined(HAVE_NETTLEHASH)
#include <nettle/nettle-meta.h>
#include <nettle/bignum.h>
@@ -165,6 +168,10 @@ int hash_init(const struct nettle_hash *
return 1;
}
+
+#endif
+
+#ifdef HAVE_DNSSEC
static int dnsmasq_rsa_verify(struct blockdata *key_data, unsigned int key_len, unsigned char *sig, size_t sig_len,
unsigned char *digest, size_t digest_len, int algo)
--- a/src/dnsmasq.h
+++ b/src/dnsmasq.h
@@ -150,7 +150,7 @@ extern int capget(cap_user_header_t head
#include <priv.h>
#endif
-#ifdef HAVE_DNSSEC
+#if defined(HAVE_DNSSEC) || defined(HAVE_NETTLEHASH)
# include <nettle/nettle-meta.h>
#endif
--- a/src/hash_questions.c
+++ b/src/hash_questions.c
@@ -28,7 +28,7 @@
#include "dnsmasq.h"
-#ifdef HAVE_DNSSEC
+#if defined(HAVE_DNSSEC) || defined(HAVE_NETTLEHASH)
unsigned char *hash_questions(struct dns_header *header, size_t plen, char *name)
{
int q;

56
package/network/services/dnsmasq/patches/0111-Small-cleanups-in-frec_src-datastucture-handling.patch Normal file
View File

@ -0,0 +1,56 @@
From 6a6e06fbb0d4690507ceaf2bb6f0d8910f3d4914 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Fri, 4 Dec 2020 18:35:11 +0000
Subject: Small cleanups in frec_src datastucture handling.
---
src/forward.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
--- a/src/forward.c
+++ b/src/forward.c
@@ -353,7 +353,10 @@ static int forward_query(int udpfd, unio
if (!daemon->free_frec_src &&
daemon->frec_src_count < daemon->ftabsize &&
(daemon->free_frec_src = whine_malloc(sizeof(struct frec_src))))
- daemon->frec_src_count++;
+ {
+ daemon->frec_src_count++;
+ daemon->free_frec_src->next = NULL;
+ }
/* If we've been spammed with many duplicates, just drop the query. */
if (daemon->free_frec_src)
@@ -390,6 +393,7 @@ static int forward_query(int udpfd, unio
forward->frec_src.orig_id = ntohs(header->id);
forward->frec_src.dest = *dst_addr;
forward->frec_src.iface = dst_iface;
+ forward->frec_src.next = NULL;
forward->new_id = get_id();
forward->fd = udpfd;
memcpy(forward->hash, hash, HASH_SIZE);
@@ -2226,16 +2230,16 @@ void free_rfd(struct randfd *rfd)
static void free_frec(struct frec *f)
{
- struct frec_src *src, *tmp;
-
- /* add back to freelist of not the record builtin to every frec. */
- for (src = f->frec_src.next; src; src = tmp)
+ struct frec_src *last;
+
+ /* add back to freelist if not the record builtin to every frec. */
+ for (last = f->frec_src.next; last && last->next; last = last->next) ;
+ if (last)
{
- tmp = src->next;
- src->next = daemon->free_frec_src;
- daemon->free_frec_src = src;
+ last->next = daemon->free_frec_src;
+ daemon->free_frec_src = f->frec_src.next;
}
-
+
f->frec_src.next = NULL;
free_rfd(f->rfd4);
f->rfd4 = NULL;

41
package/network/services/dnsmasq/patches/0112-Add-CVE-numbers-to-security-update-descriptions-in-C.patch Normal file
View File

@ -0,0 +1,41 @@
From e01e09c7125b40646aff4a582672e711a18a69a4 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Fri, 8 Jan 2021 22:50:03 +0000
Subject: Add CVE numbers to security update descriptions in CHANGELOG
---
CHANGELOG | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,16 +1,17 @@
Fix a remote buffer overflow problem in the DNSSEC code. Any
dnsmasq with DNSSEC compiled in and enabled is vulnerable to this,
- referenced by CERT VU#434904.
+ referenced by CVE-2020-25681, CVE-2020-25682, CVE-2020-25683
+ CVE-2020-25687.
Be sure to only accept UDP DNS query replies at the address
from which the query was originated. This keeps as much entropy
in the {query-ID, random-port} tuple as possible, to help defeat
- cache poisoning attacks. Refer: CERT VU#434904.
+ cache poisoning attacks. Refer: CVE-2020-25684.
Use the SHA-256 hash function to verify that DNS answers
received are for the questions originally asked. This replaces
the slightly insecure SHA-1 (when compiled with DNSSEC) or
- the very insecure CRC32 (otherwise). Refer: CERT VU#434904.
+ the very insecure CRC32 (otherwise). Refer: CVE-2020-25685.
Handle multiple identical near simultaneous DNS queries better.
Previously, such queries would all be forwarded
@@ -24,7 +25,7 @@
of the query. The new behaviour detects repeated queries and
merely stores the clients sending repeats so that when the
first query completes, the answer can be sent to all the
- clients who asked. Refer: CERT VU#434904.
+ clients who asked. Refer: CVE-2020-25686.
version 2.81

20
package/network/services/dnsmasq/patches/0113-Fix-warning-message-logic.patch Normal file
View File

@ -0,0 +1,20 @@
From 503f68dbc437df20a45aab440e6fad92062af229 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Fri, 15 Jan 2021 21:53:29 +0000
Subject: Fix warning message logic.
---
src/hash_questions.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/src/hash_questions.c
+++ b/src/hash_questions.c
@@ -43,7 +43,7 @@ unsigned char *hash_questions(struct dns
static unsigned char dummy[HASH_SIZE];
static int warned = 0;
- if (warned)
+ if (!warned)
my_syslog(LOG_ERR, _("Failed to create SHA-256 hash object"));
warned = 1;

29
package/network/services/dnsmasq/patches/0115-Update-to-new-struct-frec-fields-in-conntrack-code.patch Normal file
View File

@ -0,0 +1,29 @@
From cc0b4489c782f6b90ca118abb18e716a7a831289 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Fri, 15 Jan 2021 22:21:52 +0000
Subject: Update to new struct frec fields in conntrack code.
---
src/forward.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/src/forward.c
+++ b/src/forward.c
@@ -530,7 +530,7 @@ static int forward_query(int udpfd, unio
if (option_bool(OPT_CONNTRACK))
{
unsigned int mark;
- if (get_incoming_mark(&forward->source, &forward->dest, 0, &mark))
+ if (get_incoming_mark(&forward->frec_src.source, &forward->frec_src.dest, 0, &mark))
setsockopt(fd, SOL_SOCKET, SO_MARK, &mark, sizeof(unsigned int));
}
#endif
@@ -1178,7 +1178,7 @@ void reply_query(int fd, int family, tim
if (option_bool(OPT_CONNTRACK))
{
unsigned int mark;
- if (get_incoming_mark(&orig->source, &orig->dest, 0, &mark))
+ if (get_incoming_mark(&orig->frec_src.source, &orig->frec_src.dest, 0, &mark))
setsockopt(fd, SOL_SOCKET, SO_MARK, &mark, sizeof(unsigned int));
}
#endif

4
package/network/services/dnsmasq/patches/050-crypto-use-nettle-ecc_curve-access-functions.patch
View File

@ -15,7 +15,7 @@ Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>
--- a/src/crypto.c
+++ b/src/crypto.c
@@ -294,7 +294,7 @@ static int dnsmasq_ecdsa_verify(struct b
@@ -301,7 +301,7 @@ static int dnsmasq_ecdsa_verify(struct b
if (!(key_256 = whine_malloc(sizeof(struct ecc_point))))
return 0;
@ -24,7 +24,7 @@ Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>
}
key = key_256;
@@ -307,7 +307,7 @@ static int dnsmasq_ecdsa_verify(struct b
@@ -314,7 +314,7 @@ static int dnsmasq_ecdsa_verify(struct b
if (!(key_384 = whine_malloc(sizeof(struct ecc_point))))
return 0;