From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 57F2FC82601 for ; Tue, 3 Nov 2020 10:38:34 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 5836B22384 for ; Tue, 3 Nov 2020 10:38:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="a2b0PFcF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5836B22384 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-20328-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 25840 invoked by uid 550); 3 Nov 2020 10:38:26 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 25820 invoked from network); 3 Nov 2020 10:38:26 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1604399894; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ZK7kTdSBJkhWYXO+It5JpZizMtRKkiDqlX6IiABWQ7I=; b=a2b0PFcFMHydRjAYBRRLKvuAgUExc6OaEVtNniEa4OI23RQYiQs10jO7bq0Z88346+lJoD fhrDweHW2KHYWtwL3BFcBFalfsn7zV087SuJZDu99RoiBv/mNsde5DrPf+iIzvY+sCPcTy cnruR8Yn5EJ1jF0icfcUG+ttjVxbi7w= X-MC-Unique: kGyoSPjNOa2bGC08sRRHMw-1 From: Florian Weimer To: Szabolcs Nagy Cc: libc-alpha@sourceware.org, Jeremy Linton , Catalin Marinas , Mark Rutland , Will Deacon , Mark Brown , Kees Cook , Salvatore Mesoraca , Lennart Poettering , Topi Miettinen , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel-hardening@lists.openwall.com, linux-hardening@vger.kernel.org, "H.J. Lu" Subject: Re: [PATCH 2/4] elf: Move note processing after l_phdr is updated [BZ #26831] References: <7b008fd34f802456db3731a043ff56683b569ff7.1604393169.git.szabolcs.nagy@arm.com> Date: Tue, 03 Nov 2020 11:38:03 +0100 In-Reply-To: <7b008fd34f802456db3731a043ff56683b569ff7.1604393169.git.szabolcs.nagy@arm.com> (Szabolcs Nagy's message of "Tue, 3 Nov 2020 10:26:18 +0000") Message-ID: <87r1pabu9g.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 * Szabolcs Nagy: > Program headers are processed in two pass: after the first pass > load segments are mmapped so in the second pass target specific > note processing logic can access the notes. > > The second pass is moved later so various link_map fields are > set up that may be useful for note processing such as l_phdr. > --- > elf/dl-load.c | 30 +++++++++++++++--------------- > 1 file changed, 15 insertions(+), 15 deletions(-) > > diff --git a/elf/dl-load.c b/elf/dl-load.c > index ceaab7f18e..673cf960a0 100644 > --- a/elf/dl-load.c > +++ b/elf/dl-load.c > @@ -1259,21 +1259,6 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, > maplength, has_holes, loader); > if (__glibc_unlikely (errstring != NULL)) > goto call_lose; > - > - /* Process program headers again after load segments are mapped in > - case processing requires accessing those segments. Scan program > - headers backward so that PT_NOTE can be skipped if PT_GNU_PROPERTY > - exits. */ > - for (ph = &phdr[l->l_phnum]; ph != phdr; --ph) > - switch (ph[-1].p_type) > - { > - case PT_NOTE: > - _dl_process_pt_note (l, fd, &ph[-1]); > - break; > - case PT_GNU_PROPERTY: > - _dl_process_pt_gnu_property (l, fd, &ph[-1]); > - break; > - } > } > > if (l->l_ld == 0) > @@ -1481,6 +1466,21 @@ cannot enable executable stack as shared object requires"); > /* Assign the next available module ID. */ > l->l_tls_modid = _dl_next_tls_modid (); > > + /* Process program headers again after load segments are mapped in > + case processing requires accessing those segments. Scan program > + headers backward so that PT_NOTE can be skipped if PT_GNU_PROPERTY > + exits. */ > + for (ph = &l->l_phdr[l->l_phnum]; ph != l->l_phdr; --ph) > + switch (ph[-1].p_type) > + { > + case PT_NOTE: > + _dl_process_pt_note (l, fd, &ph[-1]); > + break; > + case PT_GNU_PROPERTY: > + _dl_process_pt_gnu_property (l, fd, &ph[-1]); > + break; > + } > + > #ifdef DL_AFTER_LOAD > DL_AFTER_LOAD (l); > #endif Is this still compatible with the CET requirements? I hope it is because the CET magic happens in _dl_open_check, so after the the code in elf/dl-load.c has run. Thanks, Florian -- Red Hat GmbH, https://de.redhat.com/ , Registered seat: Grasbrunn, Commercial register: Amtsgericht Muenchen, HRB 153243, Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs, Michael O'Neill