From patchwork Wed Jun 17 14:00:08 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Vivek Dasmohapatra X-Patchwork-Id: 39648 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id E5C0B3893666; Wed, 17 Jun 2020 14:00:38 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E5C0B3893666 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1592402439; bh=Iw2HbI5ZLpkz7m0Vq7CMjwLQFklcxw+c9UMJ+cBMwUA=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=Y3itezpRWdDfjedQLzoJyU17ThK/5UwWsNMop4hWUa//JdLgpsbWqYw1AtxMr16YK XO4Ar+7xdCNt17dfSLC9+QIpnboAE62KFGAUIN2WJyias9LskoYmBz2/LmilEQ9tHg 4lUu1XJhqzM9MJN49wRL//3kAyUHTcXtbLOn0cCI= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by sourceware.org (Postfix) with ESMTPS id 4A3D138930DE for ; Wed, 17 Jun 2020 14:00:35 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 4A3D138930DE Received: from noise.collabora.co.uk (unknown [IPv6:2001:4d48:ad56:3000:88ff:22ff:81f3:30c8]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: vivek) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 0742E2605F9 for ; Wed, 17 Jun 2020 15:00:34 +0100 (BST) To: libc-alpha@sourceware.org Subject: [RFC][PATCH v5 00/16] Proof-of-Concept implementation of RTLD_SHARED for dlmopen Date: Wed, 17 Jun 2020 15:00:08 +0100 Message-Id: <20200617140024.12777-1-vivek@collabora.com> X-Mailer: git-send-email 2.11.0 MIME-Version: 1.0 X-Spam-Status: No, score=-9.4 required=5.0 tests=BAYES_00, KAM_ASCII_DIVIDERS, KAM_DMARC_STATUS, SPF_HELO_PASS, SPF_PASS, TXREP autolearn=no autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: =?utf-8?q?Vivek_Das=C2=A0Mohapatra_via_Libc-alpha?= From: Vivek Dasmohapatra Reply-To: =?utf-8?q?Vivek_Das=C2=A0Mohapatra?= Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" This is a revision of a previous patchset that I posted here regarding https://sourceware.org/bugzilla/show_bug.cgi?id=22745 I will recap the previous introduction here: ======================================================================= As discussed in the URL above dlmopen requires a mechanism for [optionally] sharing some objects between more than one namespace. The following patchset attempts an implementation for this: If an object is loaded with the new RTLD_SHARED flag we instead ensure that a "master" copy exists (and is flagged as no-delete) in the main namespace and a thin wrapper or clone is placed in the target namespace. This patch series should address all the comments received on the earlier (v1) series, and fixes a bug in the previous (v2) series which left the r_debug struct in an inconsistent state when creating a proxy triggered the initial load of a DSO into the main namespace. ======================================================================= In addition this patch series now mplements the following: - dlmopen will implicitly apply RTLD_SHARED to the libc/libpthread group (requires a patched binutils/ld so that the libc family of DSOs can be flagged as requiring this behaviour) - LD_AUDIT paths will not apply this implict sharing rule, so audit libraries will continue to be completely isolated. - The mechanism for tagging DSOs as implicitly shared has been changed from a DT_FLAGS_1 flag to a DT_VALRNGHI/LO range dynamic tag. (Based on feedback on the binutils side of this patch series). - A flag RTLD_ISOLATE which is used inernally to suppress RTLD_SHARED behaviour when audit libraries are being loaded, and is also made available to users who really want a completely separate copy of glibc in their new namespace. - Tests for most of the new dlmopen behaviour (to be added to if this patch series is acceptable) I have not yet implemented, but plan to address once this series is accepted/acceptable: - Sensible RTLD_GLOBAL semantics for dlmopened DSOs in non-base namespaces - dl_iterate_ns_phdr (cf dl_iterate_phdr but taking a namespace argument) Vivek Das Mohapatra (16): Declare and describe the dlmopen RTLD_SHARED flag include/link.h: Update the link_map struct to allow proxies elf/dl-object.c: Implement a helper function to proxy link_map entries elf/dl-load.c, elf-dl-open.c: Implement RTLD_SHARED dlmopen proxying elf/dl-fini.c: Handle proxy link_map entries in the shutdown path elf/dl-init.c: Skip proxied link map entries in the dl init path Define a new dynamic section tag - DT_GNU_UNIQUE Abstract the loaded-DSO search code into a private helper function Compare loaded DSOs by file ID and check for DF_1_UNIQUE Use the new DSO finder helper function since we have it Use the DSO search helper to check for preloaded DT_GNU_UNIQUE DSOs When loading DSOs into alternate namespaces check for DT_GNU_UNIQUE Suppress inter-namespace DSO sharing for audit libraries dlsym, dlvsym should be able to look up symbols via DSO proxies Add a DT_GNU_UNIQUE dynamic section to the glibc cluster DSOs Add dlmopen / RTLD_SHARED tests Makeconfig | 1 + Makerules | 2 +- bits/dlfcn.h | 10 + elf/Makefile | 42 +- elf/dl-close.c | 43 +- elf/dl-fini.c | 6 +- elf/dl-init.c | 4 +- elf/dl-load.c | 204 +++++++-- elf/dl-object.c | 84 ++++ elf/dl-open.c | 99 ++++- elf/dl-sym.c | 14 + elf/elf.h | 3 +- elf/rtld.c | 2 +- elf/tst-dlmopen-common.h | 15 + elf/tst-dlmopen-main.h | 899 +++++++++++++++++++++++++++++++++++++++ elf/tst-dlmopen-modules.h | 3 + elf/tst-dlmopen-rtld-shared1.c | 74 ++++ elf/tst-dlmopen-rtld-shared2.c | 76 ++++ elf/tst-dlmopen-rtld-shared3.c | 53 +++ elf/tst-dlmopen-rtld-shared4.c | 24 ++ elf/tst-dlmopen-rtld-shared5.c | 35 ++ elf/tst-dlmopen-rtld-shared6.c | 46 ++ elf/tst-dlmopen-rtld-unique1.c | 96 +++++ elf/tst-dlmopen-rtld-unique2.c | 35 ++ elf/tst-dlmopen-rtld-unique3.c | 23 + elf/tst-dlmopen-rtld-unique4.c | 24 ++ elf/tst-dlmopen-sharedmod-norm.c | 11 + elf/tst-dlmopen-sharedmod-uniq.c | 11 + elf/tst-dlmopen-std-do-test.h | 11 + iconvdata/Makefile | 1 + include/link.h | 6 +- nptl/Makefile | 2 +- sysdeps/generic/ldsodefs.h | 9 + sysdeps/mips/bits/dlfcn.h | 10 + 34 files changed, 1922 insertions(+), 56 deletions(-) create mode 100644 elf/tst-dlmopen-common.h create mode 100644 elf/tst-dlmopen-main.h create mode 100644 elf/tst-dlmopen-modules.h create mode 100644 elf/tst-dlmopen-rtld-shared1.c create mode 100644 elf/tst-dlmopen-rtld-shared2.c create mode 100644 elf/tst-dlmopen-rtld-shared3.c create mode 100644 elf/tst-dlmopen-rtld-shared4.c create mode 100644 elf/tst-dlmopen-rtld-shared5.c create mode 100644 elf/tst-dlmopen-rtld-shared6.c create mode 100644 elf/tst-dlmopen-rtld-unique1.c create mode 100644 elf/tst-dlmopen-rtld-unique2.c create mode 100644 elf/tst-dlmopen-rtld-unique3.c create mode 100644 elf/tst-dlmopen-rtld-unique4.c create mode 100644 elf/tst-dlmopen-sharedmod-norm.c create mode 100644 elf/tst-dlmopen-sharedmod-uniq.c create mode 100644 elf/tst-dlmopen-std-do-test.h