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File _service:tar_scm:0005-resolv-Allow-short-error-responses-to-match-any-quer.patch of Package glibc
From dc512364e8490facb30f8c23fcc496d21adfc4e4 Mon Sep 17 00:00:00 2001 From: Florian Weimer <fweimer@redhat.com> Date: Wed, 24 Jul 2024 12:06:47 +0200 Subject: [PATCH 05/12] resolv: Allow short error responses to match any query (bug 31890) Reviewed-by: DJ Delorie <dj@redhat.com> (cherry picked from commit 691a3b2e9bfaba842e46a5ccb7f5e6ea144c3ade) --- NEWS | 1 + resolv/Makefile | 3 + resolv/res_send.c | 29 +++++--- resolv/tst-resolv-short-response.c | 112 +++++++++++++++++++++++++++++ 4 files changed, 135 insertions(+), 10 deletions(-) create mode 100644 resolv/tst-resolv-short-response.c diff --git a/NEWS b/NEWS index f0a0834496..c331604747 100644 --- a/NEWS +++ b/NEWS @@ -51,6 +51,7 @@ The following bugs are resolved with this release: [31183] Wide stream buffer size reduced MB_LEN_MAX bytes after bug 17522 fix [31184] FAIL: elf/tst-tlsgap [31185] Incorrect thread point access in _dl_tlsdesc_undefweak and _dl_tlsdesc_dynamic + [31890] resolv: Allow short error responses to match any DNS query [31965] rseq extension mechanism does not work as intended diff --git a/resolv/Makefile b/resolv/Makefile index 2f99eb3862..cca0748f9a 100644 --- a/resolv/Makefile +++ b/resolv/Makefile @@ -106,6 +106,7 @@ tests += \ tst-resolv-nondecimal \ tst-resolv-res_init-multi \ tst-resolv-search \ + tst-resolv-short-response \ tst-resolv-trailing \ # This test calls __res_context_send directly, which is not exported @@ -299,6 +300,8 @@ $(objpfx)tst-resolv-nondecimal: $(objpfx)libresolv.so $(shared-thread-library) $(objpfx)tst-resolv-qtypes: $(objpfx)libresolv.so $(shared-thread-library) $(objpfx)tst-resolv-rotate: $(objpfx)libresolv.so $(shared-thread-library) $(objpfx)tst-resolv-search: $(objpfx)libresolv.so $(shared-thread-library) +$(objpfx)tst-resolv-short-response: $(objpfx)libresolv.so \ + $(shared-thread-library) $(objpfx)tst-resolv-trailing: $(objpfx)libresolv.so $(shared-thread-library) $(objpfx)tst-resolv-threads: $(objpfx)libresolv.so $(shared-thread-library) $(objpfx)tst-resolv-txnid-collision: $(objpfx)libresolv.a \ diff --git a/resolv/res_send.c b/resolv/res_send.c index d098eba470..bf4ce67b1d 100644 --- a/resolv/res_send.c +++ b/resolv/res_send.c @@ -1197,19 +1197,30 @@ send_dg(res_state statp, } /* Check for the correct header layout and a matching - question. */ + question. Some recursive resolvers send REFUSED + without copying back the question section + (producing a response that is only HFIXEDSZ bytes + long). Skip query matching in this case. */ + bool thisansp_error = (anhp->rcode == SERVFAIL || + anhp->rcode == NOTIMP || + anhp->rcode == REFUSED); + bool skip_query_match = (*thisresplenp == HFIXEDSZ + && ntohs (anhp->qdcount) == 0 + && thisansp_error); int matching_query = 0; /* Default to no matching query. */ if (!recvresp1 && anhp->id == hp->id - && __libc_res_queriesmatch (buf, buf + buflen, - *thisansp, - *thisansp + *thisanssizp)) + && (skip_query_match + || __libc_res_queriesmatch (buf, buf + buflen, + *thisansp, + *thisansp + *thisanssizp))) matching_query = 1; if (!recvresp2 && anhp->id == hp2->id - && __libc_res_queriesmatch (buf2, buf2 + buflen2, - *thisansp, - *thisansp + *thisanssizp)) + && (skip_query_match + || __libc_res_queriesmatch (buf2, buf2 + buflen2, + *thisansp, + *thisansp + *thisanssizp))) matching_query = 2; if (matching_query == 0) /* Spurious UDP packet. Drop it and continue @@ -1219,9 +1230,7 @@ send_dg(res_state statp, goto wait; } - if (anhp->rcode == SERVFAIL || - anhp->rcode == NOTIMP || - anhp->rcode == REFUSED) { + if (thisansp_error) { next_ns: if (recvresp1 || (buf2 != NULL && recvresp2)) { *resplen2 = 0; diff --git a/resolv/tst-resolv-short-response.c b/resolv/tst-resolv-short-response.c new file mode 100644 index 0000000000..cf1e39876f --- /dev/null +++ b/resolv/tst-resolv-short-response.c @@ -0,0 +1,112 @@ +/* Test for spurious timeouts with short 12-byte responses (bug 31890). + Copyright (C) 2024 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 + <https://www.gnu.org/licenses/>. */ + +#include <resolv.h> +#include <support/check.h> +#include <support/resolv_test.h> +#include <support/check_nss.h> + +/* The rcode in the initial response. */ +static volatile int rcode; + +static void +response (const struct resolv_response_context *ctx, + struct resolv_response_builder *b, + const char *qname, uint16_t qclass, uint16_t qtype) +{ + switch (ctx->server_index) + { + case 0: + /* First server times out. */ + struct resolv_response_flags flags = {.rcode = rcode}; + resolv_response_init (b, flags); + break; + case 1: + /* Second server sends reply. */ + 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); + switch (qtype) + { + case T_A: + { + char ipv4[4] = {192, 0, 2, 17}; + resolv_response_add_data (b, &ipv4, sizeof (ipv4)); + } + break; + case T_AAAA: + { + char ipv6[16] + = {0x20, 0x01, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}; + resolv_response_add_data (b, &ipv6, sizeof (ipv6)); + } + break; + default: + FAIL_EXIT1 ("unexpected TYPE%d query", qtype); + } + resolv_response_close_record (b); + break; + default: + FAIL_EXIT1 ("unexpected query to server %d", ctx->server_index); + } +} + +static void +check_one (void) +{ + + /* The buggy 1-second query timeout results in 30 seconds of delay, + which triggers a test timeout failure. */ + for (int i = 0; i < 10; ++i) + { + check_hostent ("www.example", gethostbyname ("www.example"), + "name: www.example\n" + "address: 192.0.2.17\n"); + check_hostent ("www.example", gethostbyname2 ("www.example", AF_INET6), + "name: www.example\n" + "address: 2001:db8::1\n"); + } +} + +static int +do_test (void) +{ + struct resolv_test *aux = resolv_test_start + ((struct resolv_redirect_config) + { + .response_callback = response, + }); + + _res.options |= RES_SNGLKUP; + + rcode = 2; /* SERVFAIL. */ + check_one (); + + rcode = 4; /* NOTIMP. */ + check_one (); + + rcode = 5; /* REFUSED. */ + check_one (); + + resolv_test_end (aux); + + return 0; +} + +#include <support/test-driver.c> -- 2.33.0
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