From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.smtpout.orange.fr (smtp-21.smtpout.orange.fr [80.12.242.21]) by sourceware.org (Postfix) with ESMTPS id EDE623858C30 for ; Sat, 12 Nov 2022 08:45:17 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org EDE623858C30 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=orange.fr Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=orange.fr Received: from cohn ([193.248.180.53]) by smtp.orange.fr with ESMTPA id tm8aoAccWAOp2tm8aohUVJ; Sat, 12 Nov 2022 09:45:16 +0100 X-ME-Helo: cohn X-ME-Auth: ZWxpZ2lzQHdhbmFkb28uZnI= X-ME-Date: Sat, 12 Nov 2022 09:45:16 +0100 X-ME-IP: 193.248.180.53 Reply-To: From: "Christian Jullien" To: "'Corinna Vinschen'" , Subject: Is there an API to remove ALSR in Cygwin 3.4.0? Date: Sat, 12 Nov 2022 09:45:15 +0100 Organization: Eligis Message-ID: <000001d8f673$1664b400$432e1c00$@orange.fr> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01D8F67B.78291C00" X-Mailer: Microsoft Outlook 14.0 Thread-Index: Adj2cxXf29gbINjkSouY5tj4KPRWfQ== Content-Language: en-us X-Spam-Status: No, score=-0.4 required=5.0 tests=BAYES_05,FREEMAIL_FROM,HTML_MESSAGE,JMQ_SPF_NEUTRAL,KAM_DMARC_STATUS,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS,TXREP autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: This is a multipart message in MIME format. ------=_NextPart_000_0001_01D8F67B.78291C00 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hello Cygwin team, First, I would like to thank you for your efforts on Cygwin all of these years. I'm asking if there will be an API to remove ASLR with an API as on Linux: #if defined(__linux__) /* * ADDR_NO_RANDOMIZE exists since Linux 2.6.12 * With this flag set, disable address-space-layout randomization. * * Not tested but gcc could remove ALSR with the following flags: * gcc -fno-stack-protector -z execstack -no-pie ... */ const int oldpersonality = personality(ADDR_NO_RANDOMIZE); /* * It's important to use non-zero-ness of & ADDR_NO_RANDOMIZE * and not equality tests other we may go to infinite loop * with execv. */ if (!(oldpersonality & ADDR_NO_RANDOMIZE)) { /* * ASLR has been asked by first personality call but an error * may have been returned. Call personality a second time * to verify it has really been removed. */ const int newpersonality = personality(ADDR_NO_RANDOMIZE); if (newpersonality & ADDR_NO_RANDOMIZE) { execv(argv[0], argv); } } #endif Or as on macOS: if (spawned == 0) { short ps_flags = 0; pid_t pid; posix_spawn_file_actions_t actions; posix_spawnattr_t attrs; cargv[cargc++] = (char *)"--noaslr"; cargv[cargc] = NULL; (void)posix_spawn_file_actions_init(&actions); (void)posix_spawnattr_init(&attrs); ps_flags |= POSIX_SPAWN_SETEXEC; ps_flags |= _POSIX_SPAWN_DISABLE_ASLR; ret = posix_spawnattr_setflags(&attrs, ps_flags); if (ret != 0) { (void)fprintf(stderr, "%s: cannot set posix_spawn flags.\n", argv[0]); free(cargv); return ret; } (void)posix_spawnp(&pid, cargv[0], &actions, &attrs, cargv, envp); /* * returns only if posix_spawnp fails. */ (void)posix_spawnattr_destroy(&attrs); } Allowing to remove ALSR with an API, allows an application to decide what to do (from command line for example: ./myapp --no-alsr --save-core saved-image.cor; ./myapp --no-alsr --use-core saved-image.cor) My preference goes to personality support the way it is done on Linux. If a gcc flag already exists, it will force a mode instead of leaving this option to end user. My Lisp (OpenLisp) has an optional feature name 'execore' which combines lisp binary and a saved image into a single executable which fails to run of course if ALSR is on. For me, it's a wish not a strong request. Christian ------=_NextPart_000_0001_01D8F67B.78291C00--