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[71.206.142.238]) by smtp.gmail.com with ESMTPSA id h205-20020a816cd6000000b005f75f878cbdsm1344673ywc.6.2024.01.12.05.43.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Jan 2024 05:43:33 -0800 (PST) From: Joe Simmons-Talbott To: libc-alpha@sourceware.org Cc: Joe Simmons-Talbott Subject: [PATCH v4] rtld: Add glibc.rtld.enable_secure tunable. Date: Fri, 12 Jan 2024 08:43:20 -0500 Message-ID: <20240112134328.568424-1-josimmon@redhat.com> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII"; x-default=true X-Spam-Status: No, score=-13.6 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,KAM_SHORT,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Add a tunable for setting __libc_enable_secure to 1. Do not set __libc_enable_secure to 0 if the tunable is set to 0. Ignore all tunables if glib.rtld.enable_secure is set. One use-case for this addition is to enable testing code paths that depend on __libc_enable_secure being set without the need to use setxid binaries. --- Changes to v3: * Rebase and fix merge conflict in NEWS. Changes to v2: * handle the tunable in __tunables_init so that it's done in a single place. * ignore all tunables if the tunable is set. * update the testcase to only check the tunables if the enable_secure tunable is not set. * don't add tunables_strcmp as there is now already a version. Changes to v1: * handle the tunable for the dynamic loader as well. NEWS | 5 ++ elf/Makefile | 2 + elf/dl-tunables.c | 11 +++ elf/dl-tunables.list | 6 ++ elf/tst-rtld-list-tunables.exp | 1 + elf/tst-tunables-enable_secure.c | 126 +++++++++++++++++++++++++++++++ 6 files changed, 151 insertions(+) create mode 100644 elf/tst-tunables-enable_secure.c diff --git a/NEWS b/NEWS index 83ae627f47..aff44f6d7f 100644 --- a/NEWS +++ b/NEWS @@ -55,6 +55,11 @@ Major new features: unsigned char, unsigned short, unsigned int, unsigned long int and unsigned long long int, and a type-generic macro. +* A new tunable, glibc.rtld.enable_secure, used to run a program + as if it were a setuid process, enabling a number of security features. This + is currently a testing tool to allow more extensive verification tests for + AT_SECURE programs and not meant to be a security feature. + Deprecated and removed features, and other changes affecting compatibility: * The ldconfig program now skips file names containing ';' or ending in diff --git a/elf/Makefile b/elf/Makefile index 5d78b659ce..45a6aa7a8d 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -285,6 +285,7 @@ tests-static-internal := \ tst-tls1-static \ tst-tls1-static-non-pie \ tst-tunables \ + tst-tunables-enable_secure \ # tests-static-internal CRT-tst-tls1-static-non-pie := $(csu-objpfx)crt1.o @@ -2676,6 +2677,7 @@ $(objpfx)tst-glibc-hwcaps-mask.out: \ $(objpfx)tst-glibc-hwcaps-cache.out: $(objpfx)tst-glibc-hwcaps tst-tunables-ARGS = -- $(host-test-program-cmd) +tst-tunables-enable_secure-ARGS = -- $(host-test-program-cmd) $(objpfx)list-tunables.out: tst-rtld-list-tunables.sh $(objpfx)ld.so $(SHELL) $< $(objpfx)ld.so '$(test-wrapper-env)' \ diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c index 03e1a68675..d3ccd2ecd4 100644 --- a/elf/dl-tunables.c +++ b/elf/dl-tunables.c @@ -223,6 +223,17 @@ parse_tunables_string (const char *valstring, struct tunable_toset_t *tunables) { tunables[ntunables++] = (struct tunable_toset_t) { cur, value, p - value }; + + /* Ignore tunables if enable_secure is set */ + if (tunable_is_name ("glibc.rtld.enable_secure", name)) + { + tunable_num_t val = (tunable_num_t) _dl_strtoul (value, NULL); + if (val == 1) + { + __libc_enable_secure = 1; + return 0; + } + } break; } } diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list index 1b40407814..1186272c81 100644 --- a/elf/dl-tunables.list +++ b/elf/dl-tunables.list @@ -136,6 +136,12 @@ glibc { minval: 0 default: 512 } + enable_secure { + type: INT_32 + minval: 0 + maxval: 1 + default: 0 + } } mem { diff --git a/elf/tst-rtld-list-tunables.exp b/elf/tst-rtld-list-tunables.exp index 2233ea9c7c..db0e1c86e9 100644 --- a/elf/tst-rtld-list-tunables.exp +++ b/elf/tst-rtld-list-tunables.exp @@ -12,5 +12,6 @@ glibc.malloc.tcache_unsorted_limit: 0x0 (min: 0x0, max: 0x[f]+) glibc.malloc.top_pad: 0x20000 (min: 0x0, max: 0x[f]+) glibc.malloc.trim_threshold: 0x0 (min: 0x0, max: 0x[f]+) glibc.rtld.dynamic_sort: 2 (min: 1, max: 2) +glibc.rtld.enable_secure: 0 (min: 0, max: 1) glibc.rtld.nns: 0x4 (min: 0x1, max: 0x10) glibc.rtld.optional_static_tls: 0x200 (min: 0x0, max: 0x[f]+) diff --git a/elf/tst-tunables-enable_secure.c b/elf/tst-tunables-enable_secure.c new file mode 100644 index 0000000000..790d14237e --- /dev/null +++ b/elf/tst-tunables-enable_secure.c @@ -0,0 +1,126 @@ +/* Check GLIBC_TUNABLES parsing for enable_secure. + Copyright (C) 2023 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 +#include +#include + +static int restart; +#define CMDLINE_OPTIONS \ + { "restart", no_argument, &restart, 1 }, + +static const struct test_t +{ + const char *env; + int32_t expected_malloc_check; + int32_t expected_enable_secure; +} tests[] = +{ + /* Expected tunable format. */ + /* Tunables should be ignored if enable_secure is set. */ + { + "glibc.malloc.check=2:glibc.rtld.enable_secure=1", + 0, + 1, + }, + /* Tunables should be ignored if enable_secure is set. */ + { + "glibc.rtld.enable_secure=1:glibc.malloc.check=2", + 0, + 1, + }, + /* Tunables should be set if enable_secure is unset. */ + { + "glibc.rtld.enable_secure=0:glibc.malloc.check=2", + 2, + 0, + }, +}; + +static int +handle_restart (int i) +{ + if (tests[i].expected_enable_secure == 1) + { + TEST_COMPARE (1, __libc_enable_secure); + } + else + { + TEST_COMPARE (tests[i].expected_malloc_check, + TUNABLE_GET_FULL (glibc, malloc, check, int32_t, NULL)); + TEST_COMPARE (tests[i].expected_enable_secure, + TUNABLE_GET_FULL (glibc, rtld, enable_secure, int32_t, + NULL)); + } + return 0; +} + +static int +do_test (int argc, char *argv[]) +{ + /* We must have either: + - One or four parameters left if called initially: + + path to ld.so optional + + "--library-path" optional + + the library path optional + + the application name + + the test to check */ + + TEST_VERIFY_EXIT (argc == 2 || argc == 5); + + if (restart) + return handle_restart (atoi (argv[1])); + + char nteststr[INT_BUFSIZE_BOUND (int)]; + + char *spargv[10]; + { + int i = 0; + for (; i < argc - 1; i++) + spargv[i] = argv[i + 1]; + spargv[i++] = (char *) "--direct"; + spargv[i++] = (char *) "--restart"; + spargv[i++] = nteststr; + spargv[i] = NULL; + } + + for (int i = 0; i < array_length (tests); i++) + { + snprintf (nteststr, sizeof nteststr, "%d", i); + + printf ("[%d] Spawned test for %s\n", i, tests[i].env); + setenv ("GLIBC_TUNABLES", tests[i].env, 1); + struct support_capture_subprocess result + = support_capture_subprogram (spargv[0], spargv); + support_capture_subprocess_check (&result, "tst-tunables-enable_secure", + 0, sc_allow_stderr); + support_capture_subprocess_free (&result); + } + + return 0; +} + +#define TEST_FUNCTION_ARGV do_test +#include -- 2.41.0