CVE-2016-10739: getaddrinfo: Fully parse IPv4 address strings [BZ #20018]

Some tests in original commit are not included because they depend on headers that
are not present in GRTEv5 branch.

The IPv4 address parser in the getaddrinfo function is changed so that
it does not ignore trailing whitespace and all characters after it.
For backwards compatibility, the getaddrinfo function still recognizes
legacy name syntax, such as 192.000.002.010 interpreted as 192.0.2.8
(octal).

This commit does not change the behavior of inet_addr and inet_aton.
gethostbyname already had additional sanity checks (but is switched
over to the new __inet_aton_exact function for completeness as well).

To avoid sending the problematic query names over DNS, commit
6ca53a2453 ("resolv: Do not send queries
for non-host-names in nss_dns [BZ #24112]") is needed.

ChangeLog

@@ -1,3 +1,36 @@
+2019-01-21  Florian Weimer  <fweimer@redhat.com>
+
+	[BZ #20018]
+	CVE-2016-10739
+	resolv: Reject trailing characters in host names
+	* include/arpa/inet.h (__inet_aton_exact): Declare.
+	(inet_aton): Remove hidden prototype.  No longer used internally.
+	* nscd/gai.c (__inet_aton): Do not define.
+	* nscd/gethstbynm3_r.c (__inet_aton): Likewise.
+	* nss/digits_dots.c (__inet_aton): Likewise.
+	(__nss_hostname_digits_dots_context): Call __inet_aton_exact.
+	* resolv/Makefile (tests-internal): Add tst-inet_aton_exact.
+	(tests): Add tst-resolv-nondecimal, tst-resolv-trailing.
+	(tst-resolv-nondecimal): Link with libresolv.so and libpthread.
+	(tst-resolv-trailing): Likewise.
+	* resolv/Versions (GLIBC_PRIVATE): Export __inet_aton_exact from
+	libc.
+	* resolv/inet_addr.c (inet_aton_end): Remame from __inet_aton.
+	Make static.  Add endp parameter.
+	(__inet_aton_exact): New function.
+	(__inet_aton_ignore_trailing): New function, aliased to inet_aton.
+	(__inet_addr): Call inet_aton_end.
+	* resolv/res_init.c (res_vinit_1): Truncate nameserver for IPv4,
+	not just IPv6.  Call __inet_aton_exact.
+	* resolv/tst-aton.c: Switch to <support/test-driver.c>.
+	(tests): Make const.  Add additional test cases with trailing
+	characters.
+	(do_test): Use array_length.
+	* resolv/tst-inet_aton_exact.c: New file.
+	* resolv/tst-resolv-trailing.c: Likewise.
+	* resolv/tst-resolv-nondecimal.c: Likewise.
+	* sysdeps/posix/getaddrinfo.c (gaih_inet): Call __inet_aton_exact.
+
 2018-05-18  Joseph Myers  <joseph@codesourcery.com>
 
 	[BZ #22639]

NEWS

@@ -28,6 +28,10 @@ Deprecated and removed features, and other changes affecting compatibility:
 
 Security related changes:
 
+  CVE-2016-10739: The getaddrinfo function could successfully parse IPv4
+  addresses with arbitrary trailing characters, potentially leading to data
+  or command injection issues in applications.
+
   CVE-2017-18269: An SSE2-based memmove implementation for the i386
   architecture could corrupt memory.  Reported by Max Horn.
 

include/arpa/inet.h

@@ -1,10 +1,10 @@
 #include <inet/arpa/inet.h>
 
 #ifndef _ISOMAC
-extern int __inet_aton (const char *__cp, struct in_addr *__inp);
+/* Variant of inet_aton which rejects trailing garbage.  */
-libc_hidden_proto (__inet_aton)
+extern int __inet_aton_exact (const char *__cp, struct in_addr *__inp);
+libc_hidden_proto (__inet_aton_exact)
 
-libc_hidden_proto (inet_aton)
 libc_hidden_proto (inet_ntop)
 libc_hidden_proto (inet_pton)
 extern __typeof (inet_pton) __inet_pton;

nscd/gai.c

@@ -19,7 +19,6 @@
 
 /* This file uses the getaddrinfo code but it compiles it without NSCD
    support.  We just need a few symbol renames.  */
-#define __inet_aton inet_aton
 #define __ioctl ioctl
 #define __getsockname getsockname
 #define __socket socket

nscd/gethstbynm3_r.c

@@ -38,8 +38,6 @@
 #define HAVE_LOOKUP_BUFFER	1
 #define HAVE_AF			1
 
-#define __inet_aton inet_aton
-
 /* We are nscd, so we don't want to be talking to ourselves.  */
 #undef	USE_NSCD
 

nss/digits_dots.c

@@ -29,7 +29,6 @@
 #include "nsswitch.h"
 
 #ifdef USE_NSCD
-# define inet_aton __inet_aton
 # include <nscd/nscd_proto.h>
 #endif
 
@@ -160,7 +159,7 @@ __nss_hostname_digits_dots_context (struct resolv_context *ctx,
 		     255.255.255.255?  The test below will succeed
 		     spuriously... ???  */
 		  if (af == AF_INET)
-		    ok = __inet_aton (name, (struct in_addr *) host_addr);
+		    ok = __inet_aton_exact (name, (struct in_addr *) host_addr);
 		  else
 		    {
 		      assert (af == AF_INET6);

resolv/Versions

@@ -27,6 +27,7 @@ libc {
     __h_errno; __resp;
 
     __res_iclose;
+    __inet_aton_exact;
     __inet_pton_length;
     __resolv_context_get;
     __resolv_context_get_preinit;

resolv/inet_addr.c

@@ -78,29 +78,14 @@
 #include <limits.h>
 #include <errno.h>
 
-/*
+/* Check whether "cp" is a valid ASCII representation of an IPv4
- * Ascii internet address interpretation routine.
+   Internet address and convert it to a binary address.  Returns 1 if
- * The value returned is in network order.
+   the address is valid, 0 if not.  This replaces inet_addr, the
- */
+   return value from which cannot distinguish between failure and a
-in_addr_t
+   local broadcast address.  Write a pointer to the first
-__inet_addr(const char *cp) {
+   non-converted character to *endp.  */
-	struct in_addr val;
+static int
-
+inet_aton_end (const char *cp, struct in_addr *addr, const char **endp)
-	if (__inet_aton(cp, &val))
-		return (val.s_addr);
-	return (INADDR_NONE);
-}
-weak_alias (__inet_addr, inet_addr)
-
-/*
- * Check whether "cp" is a valid ascii representation
- * of an Internet address and convert to a binary address.
- * Returns 1 if the address is valid, 0 if not.
- * This replaces inet_addr, the return value from which
- * cannot distinguish between failure and a local broadcast address.
- */
-int
-__inet_aton(const char *cp, struct in_addr *addr)
 {
 	static const in_addr_t max[4] = { 0xffffffff, 0xffffff, 0xffff, 0xff };
 	in_addr_t val;
@@ -170,6 +155,7 @@ __inet_aton(const char *cp, struct in_addr *addr)
 
 	if (addr != NULL)
 		addr->s_addr = res.word | htonl (val);
+	*endp = cp;
 
 	__set_errno (saved_errno);
 	return (1);
@@ -178,6 +164,41 @@ ret_0:
 	__set_errno (saved_errno);
 	return (0);
 }
-weak_alias (__inet_aton, inet_aton)
+
-libc_hidden_def (__inet_aton)
+int
-libc_hidden_weak (inet_aton)
+__inet_aton_exact (const char *cp, struct in_addr *addr)
+{
+  struct in_addr val;
+  const char *endp;
+  /* Check that inet_aton_end parsed the entire string.  */
+  if (inet_aton_end (cp, &val, &endp) != 0 && *endp == 0)
+    {
+      *addr = val;
+      return 1;
+    }
+  else
+    return 0;
+}
+libc_hidden_def (__inet_aton_exact)
+
+/* inet_aton ignores trailing garbage.  */
+int
+__inet_aton_ignore_trailing (const char *cp, struct in_addr *addr)
+{
+  const char *endp;
+  return  inet_aton_end (cp, addr, &endp);
+}
+weak_alias (__inet_aton_ignore_trailing, inet_aton)
+
+/* ASCII IPv4 Internet address interpretation routine.  The value
+   returned is in network order.  */
+in_addr_t
+__inet_addr (const char *cp)
+{
+  struct in_addr val;
+  const char *endp;
+  if (inet_aton_end (cp, &val, &endp))
+    return val.s_addr;
+  return INADDR_NONE;
+}
+weak_alias (__inet_addr, inet_addr)

resolv/res_init.c

@@ -399,8 +399,16 @@ res_vinit_1 (FILE *fp, struct resolv_conf_parser *parser)
               cp = parser->buffer + sizeof ("nameserver") - 1;
               while (*cp == ' ' || *cp == '\t')
                 cp++;
+
+              /* Ignore trailing contents on the name server line.  */
+              {
+                char *el;
+                if ((el = strpbrk (cp, " \t\n")) != NULL)
+                  *el = '\0';
+              }
+
               struct sockaddr *sa;
-              if ((*cp != '\0') && (*cp != '\n') && __inet_aton (cp, &a))
+              if ((*cp != '\0') && (*cp != '\n') && __inet_aton_exact (cp, &a))
                 {
                   sa = allocate_address_v4 (a, NAMESERVER_PORT);
                   if (sa == NULL)
@@ -410,9 +418,6 @@ res_vinit_1 (FILE *fp, struct resolv_conf_parser *parser)
                 {
                   struct in6_addr a6;
                   char *el;
-
-                  if ((el = strpbrk (cp, " \t\n")) != NULL)
-                    *el = '\0';
                   if ((el = strchr (cp, SCOPE_DELIMITER)) != NULL)
                     *el = '\0';
                   if ((*cp != '\0') && (__inet_pton (AF_INET6, cp, &a6) > 0))
@@ -472,7 +477,7 @@ res_vinit_1 (FILE *fp, struct resolv_conf_parser *parser)
                   char separator = *cp;
                   *cp = 0;
                   struct resolv_sortlist_entry e;
-                  if (__inet_aton (net, &a))
+                  if (__inet_aton_exact (net, &a))
                     {
                       e.addr = a;
                       if (is_sort_mask (separator))
@@ -484,7 +489,7 @@ res_vinit_1 (FILE *fp, struct resolv_conf_parser *parser)
                             cp++;
                           separator = *cp;
                           *cp = 0;
-                          if (__inet_aton (net, &a))
+                          if (__inet_aton_exact (net, &a))
                             e.mask = a.s_addr;
                           else
                             e.mask = net_mask (e.addr);

resolv/tst-aton.c

@@ -1,11 +1,29 @@
+/* Test legacy IPv4 text-to-address function inet_aton.
+   Copyright (C) 1998-2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 
-
+static const struct tests
-static struct tests
 {
   const char *input;
   int valid;
@@ -16,6 +34,7 @@ static struct tests
   { "-1", 0, 0 },
   { "256", 1, 0x00000100 },
   { "256.", 0, 0 },
+  { "255a", 0, 0 },
   { "256a", 0, 0 },
   { "0x100", 1, 0x00000100 },
   { "0200.0x123456", 1, 0x80123456 },
@@ -40,7 +59,12 @@ static struct tests
   { "1.2.256.4", 0, 0 },
   { "1.2.3.0x100", 0, 0 },
   { "323543357756889", 0, 0 },
-  { "10.1.2.3.4", 0, 0},
+  { "10.1.2.3.4", 0, 0 },
+  { "192.0.2.1", 1, 0xc0000201 },
+  { "192.0.2.2\nX", 1, 0xc0000202 },
+  { "192.0.2.3 Y", 1, 0xc0000203 },
+  { "192.0.2.3Z", 0, 0 },
+  { "192.000.002.010", 1, 0xc0000208 },
 };
 
 
@@ -50,7 +74,7 @@ do_test (void)
   int result = 0;
   size_t cnt;
 
-  for (cnt = 0; cnt < sizeof (tests) / sizeof (tests[0]); ++cnt)
+  for (cnt = 0; cnt < array_length (tests); ++cnt)
     {
       struct in_addr addr;
 
@@ -73,5 +97,4 @@ do_test (void)
   return result;
 }
 
-#define TEST_FUNCTION do_test ()
+#include <support/test-driver.c>
-#include "../test-skeleton.c"

resolv/tst-inet_aton_exact.c

@@ -0,0 +1,47 @@
+/* Test internal legacy IPv4 text-to-address function __inet_aton_exact.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <arpa/inet.h>
+#include <support/check.h>
+
+static int
+do_test (void)
+{
+  struct in_addr addr = { };
+
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.1", &addr), 1);
+  TEST_COMPARE (ntohl (addr.s_addr), 0xC0000201);
+
+  TEST_COMPARE (__inet_aton_exact ("192.000.002.010", &addr), 1);
+  TEST_COMPARE (ntohl (addr.s_addr), 0xC0000208);
+  TEST_COMPARE (__inet_aton_exact ("0xC0000234", &addr), 1);
+  TEST_COMPARE (ntohl (addr.s_addr), 0xC0000234);
+
+  /* Trailing content is not accepted.  */
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.2X", &addr), 0);
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.3 Y", &addr), 0);
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.4\nZ", &addr), 0);
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.5\tT", &addr), 0);
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.6 Y", &addr), 0);
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.7\n", &addr), 0);
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.8\t", &addr), 0);
+
+  return 0;
+}
+
+#include <support/test-driver.c>

sysdeps/posix/getaddrinfo.c

@@ -504,7 +504,7 @@ gaih_inet (const char *name, const struct gaih_service *service,
 	}
 #endif
 
-      if (__inet_aton (name, (struct in_addr *) at->addr) != 0)
+      if (__inet_aton_exact (name, (struct in_addr *) at->addr) != 0)
 	{
 	  if (req->ai_family == AF_UNSPEC || req->ai_family == AF_INET)
 	    at->family = AF_INET;