From owner-freebsd-current@freebsd.org Fri Dec 20 21:26:55 2019 Return-Path: Delivered-To: freebsd-current@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 125C91E3C17 for ; Fri, 20 Dec 2019 21:26:55 +0000 (UTC) (envelope-from rysto32@gmail.com) Received: from mail-qk1-x72f.google.com (mail-qk1-x72f.google.com [IPv6:2607:f8b0:4864:20::72f]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 47fhdn6p3hz4RBS for ; Fri, 20 Dec 2019 21:26:53 +0000 (UTC) (envelope-from rysto32@gmail.com) Received: by mail-qk1-x72f.google.com with SMTP id c16so8794145qko.6 for ; Fri, 20 Dec 2019 13:26:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=2LWWQe7leq/cIvePc4FdXZapSGPGwNPSnTpaPd5/q2I=; b=ZsIVjgw542OcDtVqVNVb0dpKhr3dOA9yE7oy8xaHaAp2ueuNcndZsmQqPirsTlzxAH 38MEIAzaHHaOSKsBPAZ7K6Csku30ZL3DGq146xXA/Ch3M3cglClPkz3PJjtISwYPBlaG bf5HG36r99hBWl2J9YtQ6C2uFnT7BFCSwc+dQdqt8ZG7uOfSQ05rW5Whgdt8WYVkds8a B/8vCZF2/4YyhbPe7bAygzhEqQ44IQmAPv1jJ2YA95QK4KSpkQptQrcF2OtxD2MnMTjx qQfw5pSK1u6TiNgtBoizklYI6QE5dGGIAzI+bIcoD+hWDeMDBtcCwJa23/OG2bn5Dlu9 LEPA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=2LWWQe7leq/cIvePc4FdXZapSGPGwNPSnTpaPd5/q2I=; b=QLCDYeLSFpEvDkW1vVJTB22hmfea26cSmB6/+P+LANe6mABoMuPDbWTtu5r/4y+icA +BVCvjUFy8yu9WL2IOVGKR6G9rNhnnF9KLHnlupzdIF4R6BWumS2IIoBROe7GjlaLm1w rgp/DK3xniy7SCkNUKjfPcXaOuLucPUC1bbIYUXIMjz/dfL15t2mnGSv1xTqZFwDrQRU FMl4iwFcmVZypUUJXhDneycwmAOwBhW5dOtVeLPZwCTYUsGUfCEBD3sFImepPLwH7L6O W62dLi3zOV/PHIBdaeqkZpWcUtxNbDWXC2jMyLd3RsnWt95beMohKz7RWUaJtCY8LqaP be4Q== X-Gm-Message-State: APjAAAUglJi8tFw8AYJXnzx3th75Av7TEWc5mRQ944NvXd3xQ3DUVIR7 niLpipSbnArLQdignrtXP0+ifsp5+m9A1fGG3kHomIMN X-Google-Smtp-Source: APXvYqzaToOvWOCg4+d++lUjT0hGCoSeRHo0LqDd1mgekuWUKF6cOjN/QbJLyGiYDhBUE9FK0Nu2aTPR3VsNJ1Zbevc= X-Received: by 2002:a37:308:: with SMTP id 8mr14739194qkd.98.1576877212506; Fri, 20 Dec 2019 13:26:52 -0800 (PST) MIME-Version: 1.0 From: Ryan Stone Date: Fri, 20 Dec 2019 16:26:41 -0500 Message-ID: Subject: AT_EXECPATH aux_info vector contains path of interpreter when directly exec'ing rtld To: FreeBSD Current Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 47fhdn6p3hz4RBS X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20161025 header.b=ZsIVjgw5; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of rysto32@gmail.com designates 2607:f8b0:4864:20::72f as permitted sender) smtp.mailfrom=rysto32@gmail.com X-Spamd-Result: default: False [-3.00 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20161025]; FROM_HAS_DN(0.00)[]; R_SPF_ALLOW(-0.20)[+ip6:2607:f8b0:4000::/36]; FREEMAIL_FROM(0.00)[gmail.com]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-current@freebsd.org]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; IP_SCORE_FREEMAIL(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; IP_SCORE(0.00)[ip: (-9.37), ipnet: 2607:f8b0::/32(-2.18), asn: 15169(-1.89), country: US(-0.05)]; TO_DN_ALL(0.00)[]; DKIM_TRACE(0.00)[gmail.com:+]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; RCVD_IN_DNSWL_NONE(0.00)[f.2.7.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.4.6.8.4.0.b.8.f.7.0.6.2.list.dnswl.org : 127.0.5.0]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; DWL_DNSWL_NONE(0.00)[gmail.com.dwl.dnswl.org : 127.0.5.0] X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 20 Dec 2019 21:26:55 -0000 I've noticed that on head, if I directly execute rtld to run an executable, AT_EXECPATH contains the path to rtld on head (on 12.0-RELEASE it will contain nothing). This is causing me a problem because clang uses AT_EXECPATH to preferentially locate where it's installed, which it uses to locate its driver programs. The end result is that clang can no longer successfully be executed from a process in capability mode, whereas before I could fexecve rtld and give it a pre-opened file descriptor to /usr/bin/clang. I've put together a quick test program demonstrating the problem: https://people.freebsd.org/~rstone/getprogname.c On 12.0-RELEASE, directly executing rtld to run this program gives this output: $ /libexec/ld-elf.so.1 -- ./progname progname: progname argv[0]: ./progname elf_aux_info failed: No such file or directory On head, I get this instead: /libexec/ld-elf.so.1 -- ./progname progname: progname argv[0]: ./progname AT_EXECPATH: /libexec/ld-elf.so.1