Add --nftset option, like --ipset but for the newer nftables.

Thanks to Chen Zhenge for the original patch, which I've
reworked. Any bugs down to SRK.

CHANGELOG

@@ -5,6 +5,9 @@ version 2.87
 	Replace --address=/#/..... functionality which got
 	missed in the 2.86 domain search rewrite.
 
+	Add --nftset option, like --ipset but for the newer nftables.
+	Thanks to Chen Zhenge for the patch.
+	
 	
 version 2.86
 	Handle DHCPREBIND requests in the DHCPv6 server code.
@@ -100,6 +103,9 @@ version 2.86
 	of filename). Thanks to Ed Wildgoose for the initial patch
 	and motivation for this.
 
+	Allow adding IP address to nftables set in addition to
+	ipset.
+
 	
 version 2.85
         Fix problem with DNS retries in 2.83/2.84.

Makefile

@@ -70,6 +70,7 @@ nettle_libs =   `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_DNSSEC     $(PKG_CO
                                                         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`
+nft_libs =     `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_NFTSET $(PKG_CONFIG) --libs libnftables` 
 version =     -DVERSION='\"`$(top)/bld/get-version $(top)`\"'
 
 sum?=$(shell $(CC) -DDNSMASQ_COMPILE_OPTS $(COPTS) -E $(top)/$(SRC)/dnsmasq.h | ( md5sum 2>/dev/null || md5 ) | cut -f 1 -d ' ')
@@ -82,7 +83,7 @@ objs = cache.o rfc1035.o util.o option.o forward.o network.o \
        dhcp-common.o outpacket.o radv.o slaac.o auth.o ipset.o pattern.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 hash-questions.o domain-match.o
+       metrics.o hash-questions.o domain-match.o nftset.o
 
 hdrs = dnsmasq.h config.h dhcp-protocol.h dhcp6-protocol.h \
        dns-protocol.h radv-protocol.h ip6addr.h metrics.h
@@ -91,7 +92,7 @@ all : $(BUILDDIR)
 	@cd $(BUILDDIR) && $(MAKE) \
  top="$(top)" \
  build_cflags="$(version) $(dbus_cflags) $(idn2_cflags) $(idn_cflags) $(ct_cflags) $(lua_cflags) $(nettle_cflags)" \
- build_libs="$(dbus_libs) $(idn2_libs) $(idn_libs) $(ct_libs) $(lua_libs) $(sunos_libs) $(nettle_libs) $(gmp_libs) $(ubus_libs)" \
+ build_libs="$(dbus_libs) $(idn2_libs) $(idn_libs) $(ct_libs) $(lua_libs) $(sunos_libs) $(nettle_libs) $(gmp_libs) $(ubus_libs) $(nft_libs)" \
  -f $(top)/Makefile dnsmasq 
 
 mostly_clean :
@@ -116,7 +117,7 @@ all-i18n : $(BUILDDIR)
  top="$(top)" \
  i18n=-DLOCALEDIR=\'\"$(LOCALEDIR)\"\' \
  build_cflags="$(version) $(dbus_cflags) $(idn2_cflags) $(idn_cflags) $(ct_cflags) $(lua_cflags) $(nettle_cflags)" \
- build_libs="$(dbus_libs) $(idn2_libs) $(idn_libs) $(ct_libs) $(lua_libs) $(sunos_libs) $(nettle_libs) $(gmp_libs) $(ubus_libs)"  \
+ build_libs="$(dbus_libs) $(idn2_libs) $(idn_libs) $(ct_libs) $(lua_libs) $(sunos_libs) $(nettle_libs) $(gmp_libs) $(ubus_libs) $(nft_libs)"  \
  -f $(top)/Makefile dnsmasq
 	for f in `cd $(PO); echo *.po`; do \
 		cd $(top) && cd $(BUILDDIR) && $(MAKE) top="$(top)" -f $(top)/Makefile $${f%.po}.mo; \

dnsmasq.conf.example

@@ -85,6 +85,16 @@
 # subdomains to the vpn and search ipsets:
 #ipset=/yahoo.com/google.com/vpn,search
 
+# Add the IPs of all queries to yahoo.com, google.com, and their
+# subdomains to netfilters sets, which is equivalent to
+# 'nft add element ip test vpn { ... }; nft add element ip test search { ... }'
+#nftset=/yahoo.com/google.com/ip#test#vpn,ip#test#search
+
+# Use netfilters sets for both IPv4 and IPv6:
+# This adds all addresses in *.yahoo.com to vpn4 and vpn6 for IPv4 and IPv6 addresses.
+#nftset=/yahoo.com/4#ip#test#vpn4
+#nftset=/yahoo.com/6#ip#test#vpn6
+
 # You can control how dnsmasq talks to a server: this forces
 # queries to 10.1.2.3 to be routed via eth1
 # server=10.1.2.3@eth1

man/dnsmasq.8

@@ -550,6 +550,15 @@ These IP sets must already exist. See
 .BR ipset (8)
 for more details.
 .TP
+.B --nftset=/<domain>[/<domain>...]/[(6|4)#[<family>#]<table>#<set>[,[(6|4)#[<family>#]<table>#<set>]...]
+Similar to the \fB--ipset\fP option, but accepts one or more nftables 
+sets to add IP addresses into.
+These sets must already exist. See
+.BR nft (8)
+for more details. The family, table and set are passed directly to the nft. If the spec starts with 4# or 6# then
+only A or AAAA records respectively are added to the set. Since an nftset can hold only IPv4 or IPv6 addresses, this
+avoids errors being logged for addresses of the wrong type.
+.TP
 .B --connmark-allowlist-enable[=<mask>]
 Enables filtering of incoming DNS queries with associated Linux connection track marks
 according to individual allowlists configured via a series of \fB--connmark-allowlist\fP

src/cache.c

@@ -2060,7 +2060,7 @@ void log_query(unsigned int flags, char *name, union all_addr *addr, char *arg,
     }
   else if (flags & F_IPSET)
     {
-      source = "ipset add";
+      source = type ? "ipset add" : "nftset add";
       dest = name;
       name = arg;
       verb = daemon->addrbuff;

src/config.h

@@ -115,6 +115,10 @@ HAVE_IPSET
     define this to include the ability to selectively add resolved ip addresses
     to given ipsets.
 
+HAVE_NFTSET
+    define this to include the ability to selectively add resolved ip addresses
+    to given nftables sets.
+
 HAVE_AUTH
    define this to include the facility to act as an authoritative DNS
    server for one or more zones.
@@ -192,7 +196,7 @@ RESOLVFILE
 /* #define HAVE_CONNTRACK */
 /* #define HAVE_CRYPTOHASH */
 /* #define HAVE_DNSSEC */
-
+/* #define HAVE_NFTSET */
 
 /* Default locations for important system files. */
 
@@ -420,6 +424,10 @@ static char *compile_opts =
 "no-"
 #endif
 "ipset "
+#ifndef HAVE_NFTSET
+"no-"
+#endif
+"nftset "
 #ifndef HAVE_AUTH
 "no-"
 #endif

src/dnsmasq.c

@@ -346,6 +346,16 @@ int main (int argc, char **argv)
     }
 #endif
 
+#ifdef HAVE_NFTSET
+  if (daemon->nftsets)
+    {
+      nftset_init();
+#  ifdef HAVE_LINUX_NETWORK
+      need_cap_net_admin = 1;
+#  endif
+    }
+#endif
+
 #if  defined(HAVE_LINUX_NETWORK)
   netlink_warn = netlink_init();
 #elif defined(HAVE_BSD_NETWORK)

src/dnsmasq.h

@@ -1114,7 +1114,7 @@ extern struct daemon {
   struct rebind_domain *no_rebind;
   int server_has_wildcard;
   int serverarraysz, serverarrayhwm;
-  struct ipsets *ipsets;
+  struct ipsets *ipsets, *nftsets;
   u32 allowlist_mask;
   struct allowlist *allowlists;
   int log_fac; /* log facility */
@@ -1303,8 +1303,8 @@ unsigned int extract_request(struct dns_header *header, size_t qlen,
 			       char *name, unsigned short *typep);
 void setup_reply(struct dns_header *header, unsigned int flags, int ede);
 int extract_addresses(struct dns_header *header, size_t qlen, char *name,
-		      time_t now, char **ipsets, int is_sign, int check_rebind,
-		      int no_cache_dnssec, int secure, int *doctored);
+		      time_t now, struct ipsets *ipsets, struct ipsets *nftsets, int is_sign,
+                      int check_rebind, int no_cache_dnssec, int secure, int *doctored);
 #if defined(HAVE_CONNTRACK) && defined(HAVE_UBUS)
 void report_addresses(struct dns_header *header, size_t len, u32 mark);
 #endif
@@ -1588,6 +1588,12 @@ void ipset_init(void);
 int add_to_ipset(const char *setname, const union all_addr *ipaddr, int flags, int remove);
 #endif
 
+/* nftset.c */
+#ifdef HAVE_NFTSET
+void nftset_init(void);
+int add_to_nftset(const char *setpath, const union all_addr *ipaddr, int flags, int remove);
+#endif
+
 /* pattern.c */
 #ifdef HAVE_CONNTRACK
 int is_valid_dns_name(const char *value);

src/forward.c

@@ -556,12 +556,33 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
   return 0;
 }
 
+static struct ipsets *domain_find_sets(struct ipsets *setlist, const char *domain) {
+  /* Similar algorithm to search_servers. */
+  struct ipsets *ipset_pos, *ret = NULL;
+  unsigned int namelen = strlen(domain);
+  unsigned int matchlen = 0;
+  for (ipset_pos = setlist; ipset_pos; ipset_pos = ipset_pos->next) 
+    {
+      unsigned int domainlen = strlen(ipset_pos->domain);
+      const char *matchstart = domain + namelen - domainlen;
+      if (namelen >= domainlen && hostname_isequal(matchstart, ipset_pos->domain) &&
+          (domainlen == 0 || namelen == domainlen || *(matchstart - 1) == '.' ) &&
+          domainlen >= matchlen) 
+        {
+          matchlen = domainlen;
+          ret = ipset_pos;
+        }
+    }
+
+  return ret;
+}
+
 static size_t process_reply(struct dns_header *header, time_t now, struct server *server, size_t n, int check_rebind, 
 			    int no_cache, int cache_secure, int bogusanswer, int ad_reqd, int do_bit, int added_pheader, 
 			    int check_subnet, union mysockaddr *query_source, unsigned char *limit, int ede)
 {
   unsigned char *pheader, *sizep;
-  char **sets = 0;
+  struct ipsets *ipsets = NULL, *nftsets = NULL;
   int munged = 0, is_sign;
   unsigned int rcode = RCODE(header);
   size_t plen; 
@@ -572,24 +593,12 @@ static size_t process_reply(struct dns_header *header, time_t now, struct server
 
 #ifdef HAVE_IPSET
   if (daemon->ipsets && extract_request(header, n, daemon->namebuff, NULL))
-    {
-      /* Similar algorithm to search_servers. */
-      struct ipsets *ipset_pos;
-      unsigned int namelen = strlen(daemon->namebuff);
-      unsigned int matchlen = 0;
-      for (ipset_pos = daemon->ipsets; ipset_pos; ipset_pos = ipset_pos->next) 
-	{
-	  unsigned int domainlen = strlen(ipset_pos->domain);
-	  char *matchstart = daemon->namebuff + namelen - domainlen;
-	  if (namelen >= domainlen && hostname_isequal(matchstart, ipset_pos->domain) &&
-	      (domainlen == 0 || namelen == domainlen || *(matchstart - 1) == '.' ) &&
-	      domainlen >= matchlen) 
-	    {
-	      matchlen = domainlen;
-	      sets = ipset_pos->sets;
-	    }
-	}
-    }
+    ipsets = domain_find_sets(daemon->ipsets, daemon->namebuff);
+#endif
+
+#ifdef HAVE_NFTSET
+  if (daemon->nftsets && extract_request(header, n, daemon->namebuff, NULL))
+    nftsets = domain_find_sets(daemon->nftsets, daemon->namebuff);
 #endif
 
   if ((pheader = find_pseudoheader(header, n, &plen, &sizep, &is_sign, NULL)))
@@ -698,7 +707,7 @@ static size_t process_reply(struct dns_header *header, time_t now, struct server
 	    }
 	}
       
-      if (extract_addresses(header, n, daemon->namebuff, now, sets, is_sign, check_rebind, no_cache, cache_secure, &doctored))
+      if (extract_addresses(header, n, daemon->namebuff, now, ipsets, nftsets, is_sign, check_rebind, no_cache, cache_secure, &doctored))
 	{
 	  my_syslog(LOG_WARNING, _("possible DNS-rebind attack detected: %s"), daemon->namebuff);
 	  munged = 1;

src/nftset.c

@@ -0,0 +1,94 @@
+/* dnsmasq is Copyright (c) 2000-2021 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/>.
+*/
+
+
+#include "dnsmasq.h"
+
+#if defined (HAVE_NFTSET) && defined (HAVE_LINUX_NETWORK)
+
+#include <nftables/libnftables.h>
+
+#include <string.h>
+#include <arpa/inet.h>
+
+static struct nft_ctx *ctx = NULL;
+static const char *cmd_add = "add element %s { %s }";
+static const char *cmd_del = "delete element %s { %s }";
+
+void nftset_init()
+{
+  ctx = nft_ctx_new(NFT_CTX_DEFAULT);
+  if (ctx == NULL)
+    die(_("failed to create nftset context"), NULL, EC_MISC);
+
+  /* disable libnftables output */
+  nft_ctx_buffer_error(ctx);
+}
+
+int add_to_nftset(const char *setname, const union all_addr *ipaddr, int flags, int remove)
+{
+  const char *cmd = remove ? cmd_del : cmd_add;
+  int ret, af = (flags & F_IPV4) ? AF_INET : AF_INET6;
+  size_t new_sz;
+  char *new, *err, *nl;
+  static char *cmd_buf = NULL;
+  static size_t cmd_buf_sz = 0;
+
+  inet_ntop(af, ipaddr, daemon->addrbuff, ADDRSTRLEN);
+
+  if (setname[1] == ' ' && (setname[0] == '4' || setname[0] == '6'))
+    {
+      if (setname[0] == '4' && !(flags & F_IPV4))
+	return -1;
+
+      if (setname[0] == '6' && !(flags & F_IPV6))
+	return -1;
+
+      setname += 2;
+    }
+  
+  if (cmd_buf_sz == 0)
+    new_sz = 150; /* initial allocation */
+  else
+    new_sz = snprintf(cmd_buf, cmd_buf_sz, cmd, setname, daemon->addrbuff);
+  
+  if (new_sz > cmd_buf_sz)
+    {
+      if (!(new = whine_malloc(new_sz + 10)))
+	return 0;
+
+      if (cmd_buf)
+	free(cmd_buf);
+      cmd_buf = new;
+      cmd_buf_sz = new_sz + 10;
+      snprintf(cmd_buf, cmd_buf_sz, cmd, setname, daemon->addrbuff);
+    }
+
+  ret = nft_run_cmd_from_buffer(ctx, cmd_buf);
+  err = (char *)nft_ctx_get_error_buffer(ctx);
+
+  if (ret != 0)
+    {
+      /* Log only first line of error return. */
+      if ((nl = strchr(err, '\n')))
+	*nl = 0;
+      my_syslog(LOG_ERR,  "nftset %s %s", setname, err);
+    }
+  
+  return ret;
+}
+
+#endif

src/option.c

@@ -174,6 +174,7 @@ struct myoption {
 #define LOPT_CMARK_ALST_EN 365
 #define LOPT_CMARK_ALST    366
 #define LOPT_QUIET_TFTP    367
+#define LOPT_NFTSET        368
  
 #ifdef HAVE_GETOPT_LONG
 static const struct option opts[] =  
@@ -327,6 +328,7 @@ static const struct myoption opts[] =
     { "auth-sec-servers", 1, 0, LOPT_AUTHSFS },
     { "auth-peer", 1, 0, LOPT_AUTHPEER }, 
     { "ipset", 1, 0, LOPT_IPSET },
+    { "nftset", 1, 0, LOPT_NFTSET },
     { "connmark-allowlist-enable", 2, 0, LOPT_CMARK_ALST_EN },
     { "connmark-allowlist", 1, 0, LOPT_CMARK_ALST },
     { "synth-domain", 1, 0, LOPT_SYNTH },
@@ -514,6 +516,7 @@ static struct {
   { LOPT_AUTHSFS, ARG_DUP, "<NS>[,<NS>...]", gettext_noop("Secondary authoritative nameservers for forward domains"), NULL },
   { LOPT_AUTHPEER, ARG_DUP, "<ipaddr>[,<ipaddr>...]", gettext_noop("Peers which are allowed to do zone transfer"), NULL },
   { LOPT_IPSET, ARG_DUP, "/<domain>[/<domain>...]/<ipset>...", gettext_noop("Specify ipsets to which matching domains should be added"), NULL },
+  { LOPT_NFTSET, ARG_DUP, "/<domain>[/<domain>...]/<nftset>...", gettext_noop("Specify nftables sets to which matching domains should be added"), NULL },
   { LOPT_CMARK_ALST_EN, ARG_ONE, "[=<mask>]", gettext_noop("Enable filtering of DNS queries with connection-track marks."), NULL },
   { LOPT_CMARK_ALST, ARG_DUP, "<connmark>[/<mask>][,<pattern>[/<pattern>...]]", gettext_noop("Set allowed DNS patterns for a connection-track mark."), NULL },
   { LOPT_SYNTH, ARG_DUP, "<domain>,<range>,[<prefix>]", gettext_noop("Specify a domain and address range for synthesised names"), NULL },
@@ -2850,13 +2853,27 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
       }
 
     case LOPT_IPSET: /* --ipset */
+    case LOPT_NFTSET: /* --nftset */
 #ifndef HAVE_IPSET
-      ret_err(_("recompile with HAVE_IPSET defined to enable ipset directives"));
-      break;
-#else
+      if (option == LOPT_IPSET)
+        {
+          ret_err(_("recompile with HAVE_IPSET defined to enable ipset directives"));
+          break;
+        }
+#endif
+#ifndef HAVE_NFTSET
+      if (option == LOPT_NFTSET)
+        {
+          ret_err(_("recompile with HAVE_NFTSET defined to enable nftset directives"));
+          break;
+        }
+#endif
+
       {
 	 struct ipsets ipsets_head;
 	 struct ipsets *ipsets = &ipsets_head;
+         struct ipsets **daemon_sets =
+           (option == LOPT_IPSET) ? &daemon->ipsets : &daemon->nftsets;
 	 int size;
 	 char *end;
 	 char **sets, **sets_pos;
@@ -2901,19 +2918,24 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 	 sets = sets_pos = opt_malloc(sizeof(char *) * size);
 	 
 	 do {
+	   char *p;
 	   end = split(arg);
-	   *sets_pos++ = opt_string_alloc(arg);
+	   *sets_pos = opt_string_alloc(arg);
+	   /* Use '#' to delimit table and set */
+	   if (option == LOPT_NFTSET)
+	     while ((p = strchr(*sets_pos, '#')))
+	       *p = ' ';
+	   sets_pos++;
 	   arg = end;
 	 } while (end);
 	 *sets_pos = 0;
 	 for (ipsets = &ipsets_head; ipsets->next; ipsets = ipsets->next)
 	   ipsets->next->sets = sets;
-	 ipsets->next = daemon->ipsets;
-	 daemon->ipsets = ipsets_head.next;
+	 ipsets->next = *daemon_sets;
+	 *daemon_sets = ipsets_head.next;
 	 
 	 break;
       }
-#endif
       
     case LOPT_CMARK_ALST_EN: /* --connmark-allowlist-enable */
 #ifndef HAVE_CONNTRACK

src/rfc1035.c

@@ -540,8 +540,8 @@ static int print_txt(struct dns_header *header, const size_t qlen, char *name,
    expired and cleaned out that way. 
    Return 1 if we reject an address because it look like part of dns-rebinding attack. */
 int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t now, 
-		      char **ipsets, int is_sign, int check_rebind, int no_cache_dnssec,
-		      int secure, int *doctored)
+		      struct ipsets *ipsets, struct ipsets *nftsets, int is_sign, int check_rebind,
+		      int no_cache_dnssec, int secure, int *doctored)
 {
   unsigned char *p, *p1, *endrr, *namep;
   int j, qtype, qclass, aqtype, aqclass, ardlen, res, searched_soa = 0;
@@ -551,6 +551,11 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
   char **ipsets_cur;
 #else
   (void)ipsets; /* unused */
+#endif
+#ifdef HAVE_NFTSET
+  char **nftsets_cur;
+#else
+  (void)nftsets; /* unused */
 #endif
   int found = 0, cname_count = CNAME_CHAIN;
   struct crec *cpp = NULL;
@@ -843,14 +848,15 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
 		  
 #ifdef HAVE_IPSET
 		  if (ipsets && (flags & (F_IPV4 | F_IPV6)))
-		    {
-		      ipsets_cur = ipsets;
-		      while (*ipsets_cur)
-			{
-			  log_query((flags & (F_IPV4 | F_IPV6)) | F_IPSET, name, &addr, *ipsets_cur, 0);
-			  add_to_ipset(*ipsets_cur++, &addr, flags, 0);
-			}
-		    }
+		    for (ipsets_cur = ipsets->sets; *ipsets_cur; ipsets_cur++)
+		      if (add_to_ipset(*ipsets_cur, &addr, flags, 0) == 0)
+			log_query((flags & (F_IPV4 | F_IPV6)) | F_IPSET, ipsets->domain, &addr, *ipsets_cur, 1);
+#endif
+#ifdef HAVE_NFTSET
+		  if (nftsets && (flags & (F_IPV4 | F_IPV6)))
+		    for (nftsets_cur = nftsets->sets; *nftsets_cur; nftsets_cur++)
+		      if (add_to_nftset(*nftsets_cur, &addr, flags, 0) == 0)
+			log_query((flags & (F_IPV4 | F_IPV6)) | F_IPSET, nftsets->domain, &addr, *nftsets_cur, 0);
 #endif
 		}