From patchwork Tue Dec 17 21:47:20 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adhemerval Zanella Netto X-Patchwork-Id: 36926 Received: (qmail 110723 invoked by alias); 17 Dec 2019 21:47:48 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 110685 invoked by uid 89); 17 Dec 2019 21:47:48 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-21.9 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, RCVD_IN_DNSWL_NONE, SPF_PASS autolearn=ham version=3.3.1 spammy= X-HELO: mail-pj1-f66.google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:subject:date:message-id:in-reply-to:references; bh=cdhT9pkFyuo/DsH5l2GQyUgJuqDHBxRQFxXTskLU8X4=; b=RTC9IXEHnjNJRxAEMhigKGbmHu+OGFOvKo8v2anFjNaij9L/1XxwwOs20j9ExBQpOr 8JBVmyQ+256ID1T/rqruNKFtZ14h7oS+XRJoVKFLOHffllfYClMDYRrS7y8DaQRcQpZW Y2zpHiCpiq4x/OwppCRH9KXbwb/OWw0jYYWrAi46OKTa3hATiAeH6924cWVCd0z3LFFR oiCpPS9oIkzIopZWncPiRqKGJBH/2HhSAlK5JPNiH0e7TP2d5IFN3KSncX1OoVtK54L1 VgmwdU750GdIXVySTGk+YpwlVbpY3WX5TnbUHhn8GgaQkhmk9qArdBl824RthVcAg7h6 QSkg== Return-Path: From: Adhemerval Zanella To: libc-alpha@sourceware.org Subject: [PATCH v3 08/16] elf: Enable relro for static build Date: Tue, 17 Dec 2019 18:47:20 -0300 Message-Id: <20191217214728.2886-8-adhemerval.zanella@linaro.org> In-Reply-To: <20191217214728.2886-1-adhemerval.zanella@linaro.org> References: <20191217214728.2886-1-adhemerval.zanella@linaro.org> Changes from previous version: - The tests were removed and instead I will use the ones proposed by Florian's patch 'elf: Add tests for working RELRO protection' [1]. I also plan to send additional coverage for '.data.rel.ro' which trigger failures for the static case on both partial and full relro which is fixed by this patch once the patch is upstream. Reviewed-by: Siddhesh Poyarekar --- The code is similar to the one at elf/dl-reloc.c, where it checks for the l_relro_size from the link_map (obtained from PT_GNU_RELRO header from program headers) and calls_dl_protected_relro. Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu, aarch64-linux-gnu, s390x-linux-gnu, and sparc64-linux-gnu. I also check with --enable-static pie on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu which seems the only architectures where static PIE is actually working (as per 9d7a3741c9e, on arm-linux-gnueabihf, powerpc64{le}-linux-gnu, and s390x-linux-gnu I am seeing runtime issues not related to my patch). [1] https://sourceware.org/ml/libc-alpha/2019-10/msg00059.html --- elf/dl-support.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/elf/dl-support.c b/elf/dl-support.c index 5526d5ee6e..b2b1b12f6f 100644 --- a/elf/dl-support.c +++ b/elf/dl-support.c @@ -367,14 +367,24 @@ _dl_non_dynamic_init (void) if (_dl_platform != NULL) _dl_platformlen = strlen (_dl_platform); - /* Scan for a program header telling us the stack is nonexecutable. */ if (_dl_phdr != NULL) - for (uint_fast16_t i = 0; i < _dl_phnum; ++i) - if (_dl_phdr[i].p_type == PT_GNU_STACK) + for (const ElfW(Phdr) *ph = _dl_phdr; ph < &_dl_phdr[_dl_phnum]; ++ph) + switch (ph->p_type) { - _dl_stack_flags = _dl_phdr[i].p_flags; + /* Check if the stack is nonexecutable. */ + case PT_GNU_STACK: + _dl_stack_flags = ph->p_flags; + break; + + case PT_GNU_RELRO: + _dl_main_map.l_relro_addr = ph->p_vaddr; + _dl_main_map.l_relro_size = ph->p_memsz; break; } + + /* Setup relro on the binary itself. */ + if (_dl_main_map.l_relro_size != 0) + _dl_protect_relro (&_dl_main_map); } #ifdef DL_SYSINFO_IMPLEMENTATION