From b3b37f1a5559a7620e31c8053ed1b44f798f2b6d Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Sat, 31 Dec 2016 20:22:09 +0100 Subject: [PATCH] CVE-2015-5180: resolv: Fix crash with internal QTYPE [BZ #18784] Also rename T_UNSPEC because an upcoming public header file update will use that name. (cherry picked from commit fc82b0a2dfe7dbd35671c10510a8da1043d746a5) --- ChangeLog | 14 ++++ NEWS | 6 ++ include/arpa/nameser_compat.h | 6 +- resolv/Makefile | 5 ++ resolv/nss_dns/dns-host.c | 2 +- resolv/res_mkquery.c | 4 + resolv/res_query.c | 6 +- resolv/tst-resolv-qtypes.c | 185 ++++++++++++++++++++++++++++++++++++++++++ 8 files changed, 221 insertions(+), 7 deletions(-) create mode 100644 resolv/tst-resolv-qtypes.c diff --git a/include/arpa/nameser_compat.h b/include/arpa/nameser_compat.h index 2e735ed..7c0deed 100644 --- a/include/arpa/nameser_compat.h +++ b/include/arpa/nameser_compat.h @@ -1,8 +1,8 @@ #ifndef _ARPA_NAMESER_COMPAT_ #include -/* Picksome unused number to represent lookups of IPv4 and IPv6 (i.e., - T_A and T_AAAA). */ -#define T_UNSPEC 62321 +/* The number is outside the 16-bit RR type range and is used + internally by the implementation. */ +#define T_QUERY_A_AND_AAAA 439963904 #endif diff --git a/resolv/Makefile b/resolv/Makefile index 8be41d3..a4c86b9 100644 --- a/resolv/Makefile +++ b/resolv/Makefile @@ -40,6 +40,9 @@ ifeq ($(have-thread-library),yes) extra-libs += libanl routines += gai_sigqueue tests += tst-res_hconf_reorder + +# This test sends millions of packets and is rather slow. +xtests += tst-resolv-qtypes endif extra-libs-others = $(extra-libs) libresolv-routines := gethnamaddr res_comp res_debug \ @@ -117,3 +120,5 @@ tst-leaks2-ENV = MALLOC_TRACE=$(objpfx)tst-leaks2.mtrace $(objpfx)mtrace-tst-leaks2.out: $(objpfx)tst-leaks2.out $(common-objpfx)malloc/mtrace $(objpfx)tst-leaks2.mtrace > $@; \ $(evaluate-test) + +$(objpfx)tst-resolv-qtypes: $(objpfx)libresolv.so $(shared-thread-library) diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c index 5f9e357..d16fa4b 100644 --- a/resolv/nss_dns/dns-host.c +++ b/resolv/nss_dns/dns-host.c @@ -323,7 +323,7 @@ _nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat, int olderr = errno; enum nss_status status; - int n = __libc_res_nsearch (&_res, name, C_IN, T_UNSPEC, + int n = __libc_res_nsearch (&_res, name, C_IN, T_QUERY_A_AND_AAAA, host_buffer.buf->buf, 2048, &host_buffer.ptr, &ans2p, &nans2p, &resplen2, &ans2p_malloced); if (n >= 0) diff --git a/resolv/res_mkquery.c b/resolv/res_mkquery.c index 12f9730..d80b531 100644 --- a/resolv/res_mkquery.c +++ b/resolv/res_mkquery.c @@ -103,6 +103,10 @@ res_nmkquery(res_state statp, int n; u_char *dnptrs[20], **dpp, **lastdnptr; + if (class < 0 || class > 65535 + || type < 0 || type > 65535) + return -1; + #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_nmkquery(%s, %s, %s, %s)\n", diff --git a/resolv/res_query.c b/resolv/res_query.c index 944d1a9..07dc6f6 100644 --- a/resolv/res_query.c +++ b/resolv/res_query.c @@ -122,7 +122,7 @@ __libc_res_nquery(res_state statp, int n, use_malloc = 0; u_int oflags = statp->_flags; - size_t bufsize = (type == T_UNSPEC ? 2 : 1) * QUERYSIZE; + size_t bufsize = (type == T_QUERY_A_AND_AAAA ? 2 : 1) * QUERYSIZE; u_char *buf = alloca (bufsize); u_char *query1 = buf; int nquery1 = -1; @@ -137,7 +137,7 @@ __libc_res_nquery(res_state statp, printf(";; res_query(%s, %d, %d)\n", name, class, type); #endif - if (type == T_UNSPEC) + if (type == T_QUERY_A_AND_AAAA) { n = res_nmkquery(statp, QUERY, name, class, T_A, NULL, 0, NULL, query1, bufsize); @@ -190,7 +190,7 @@ __libc_res_nquery(res_state statp, if (__builtin_expect (n <= 0, 0) && !use_malloc) { /* Retry just in case res_nmkquery failed because of too short buffer. Shouldn't happen. */ - bufsize = (type == T_UNSPEC ? 2 : 1) * MAXPACKET; + bufsize = (type == T_QUERY_A_AND_AAAA ? 2 : 1) * MAXPACKET; buf = malloc (bufsize); if (buf != NULL) { query1 = buf; diff --git a/resolv/tst-resolv-qtypes.c b/resolv/tst-resolv-qtypes.c new file mode 100644 index 0000000..b3e60c6 --- /dev/null +++ b/resolv/tst-resolv-qtypes.c @@ -0,0 +1,185 @@ +/* Exercise low-level query functions with different QTYPEs. + Copyright (C) 2016 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 + . */ + +#include +#include +#include +#include +#include +#include +#include +#include + +/* If ture, the response function will send the actual response packet + over TCP instead of UDP. */ +static volatile bool force_tcp; + +/* Send back a fake resource record matching the QTYPE. */ +static void +response (const struct resolv_response_context *ctx, + struct resolv_response_builder *b, + const char *qname, uint16_t qclass, uint16_t qtype) +{ + if (force_tcp && ctx->tcp) + { + resolv_response_init (b, (struct resolv_response_flags) { .tc = 1 }); + resolv_response_add_question (b, qname, qclass, qtype); + return; + } + + resolv_response_init (b, (struct resolv_response_flags) { }); + resolv_response_add_question (b, qname, qclass, qtype); + resolv_response_section (b, ns_s_an); + resolv_response_open_record (b, qname, qclass, qtype, 0); + resolv_response_add_data (b, &qtype, sizeof (qtype)); + resolv_response_close_record (b); +} + +static const const char *domain = "www.example.com"; + +static int +wrap_res_query (int type, unsigned char *answer, int answer_length) +{ + return res_query (domain, C_IN, type, answer, answer_length); +} + +static int +wrap_res_search (int type, unsigned char *answer, int answer_length) +{ + return res_query (domain, C_IN, type, answer, answer_length); +} + +static int +wrap_res_querydomain (int type, unsigned char *answer, int answer_length) +{ + return res_querydomain ("www", "example.com", C_IN, type, + answer, answer_length); +} + +static int +wrap_res_send (int type, unsigned char *answer, int answer_length) +{ + unsigned char buf[512]; + int ret = res_mkquery (QUERY, domain, C_IN, type, + (const unsigned char *) "", 0, NULL, + buf, sizeof (buf)); + if (type < 0 || type >= 65536) + { + /* res_mkquery fails for out-of-range record types. */ + TEST_VERIFY_EXIT (ret == -1); + return -1; + } + TEST_VERIFY_EXIT (ret > 12); /* DNS header length. */ + return res_send (buf, ret, answer, answer_length); +} + +static int +wrap_res_nquery (int type, unsigned char *answer, int answer_length) +{ + return res_nquery (&_res, domain, C_IN, type, answer, answer_length); +} + +static int +wrap_res_nsearch (int type, unsigned char *answer, int answer_length) +{ + return res_nquery (&_res, domain, C_IN, type, answer, answer_length); +} + +static int +wrap_res_nquerydomain (int type, unsigned char *answer, int answer_length) +{ + return res_nquerydomain (&_res, "www", "example.com", C_IN, type, + answer, answer_length); +} + +static int +wrap_res_nsend (int type, unsigned char *answer, int answer_length) +{ + unsigned char buf[512]; + int ret = res_nmkquery (&_res, QUERY, domain, C_IN, type, + (const unsigned char *) "", 0, NULL, + buf, sizeof (buf)); + if (type < 0 || type >= 65536) + { + /* res_mkquery fails for out-of-range record types. */ + TEST_VERIFY_EXIT (ret == -1); + return -1; + } + TEST_VERIFY_EXIT (ret > 12); /* DNS header length. */ + return res_nsend (&_res, buf, ret, answer, answer_length); +} + +static void +test_function (const char *fname, + int (*func) (int type, + unsigned char *answer, int answer_length)) +{ + unsigned char buf[512]; + for (int tcp = 0; tcp < 2; ++tcp) + { + force_tcp = tcp; + for (unsigned int type = 1; type <= 65535; ++type) + { + if (test_verbose) + printf ("info: sending QTYPE %d with %s (tcp=%d)\n", + type, fname, tcp); + int ret = func (type, buf, sizeof (buf)); + if (ret != 47) + FAIL_EXIT1 ("%s tcp=%d qtype=%d return value %d", + fname,tcp, type, ret); + /* One question, one answer record. */ + TEST_VERIFY (memcmp (buf + 4, "\0\1\0\1\0\0\0\0", 8) == 0); + /* Question section. */ + static const char qname[] = "\3www\7example\3com"; + size_t qname_length = sizeof (qname); + TEST_VERIFY (memcmp (buf + 12, qname, qname_length) == 0); + /* RDATA part of answer. */ + uint16_t type16 = type; + TEST_VERIFY (memcmp (buf + ret - 2, &type16, sizeof (type16)) == 0); + } + } + + TEST_VERIFY (func (-1, buf, sizeof (buf) == -1)); + TEST_VERIFY (func (65536, buf, sizeof (buf) == -1)); +} + +static int +do_test (void) +{ + struct resolv_redirect_config config = + { + .response_callback = response, + }; + struct resolv_test *obj = resolv_test_start (config); + + test_function ("res_query", &wrap_res_query); + test_function ("res_search", &wrap_res_search); + test_function ("res_querydomain", &wrap_res_querydomain); + test_function ("res_send", &wrap_res_send); + + test_function ("res_nquery", &wrap_res_nquery); + test_function ("res_nsearch", &wrap_res_nsearch); + test_function ("res_nquerydomain", &wrap_res_nquerydomain); + test_function ("res_nsend", &wrap_res_nsend); + + resolv_test_end (obj); + return 0; +} + +#define TIMEOUT 300 +#include -- 2.9.3