From patchwork Wed Feb 14 20:06:35 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 10219847 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 05506601C2 for ; Wed, 14 Feb 2018 20:07:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E44F628618 for ; Wed, 14 Feb 2018 20:07:38 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D8C5A28680; Wed, 14 Feb 2018 20:07:38 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.3 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id BC47C28618 for ; Wed, 14 Feb 2018 20:07:37 +0000 (UTC) Received: (qmail 3664 invoked by uid 550); 14 Feb 2018 20:07:10 -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: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 3549 invoked from network); 14 Feb 2018 20:07:05 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=rXFAN8U6MUR2Ms1O38JAINd4/CR3pDfFKafU1ChRMiA=; b=L1rbVTWKe7oEy++n8DV5Au5gNTb2lEpTv8y2XRljb9G5aS7zZ37jcPv9V+0I54cAB0 qQLb4S/iT/df4lMQvnuZ6A7B9lLwQ3t9dmG/6BAsF5iWCeB2gP/bynVb8rCtmcEB38Bu DfDiEq+Jl4+YN4FWEvuak9h8fIj57AH4Ak+Dg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=rXFAN8U6MUR2Ms1O38JAINd4/CR3pDfFKafU1ChRMiA=; b=NmzV0A8n+fKr6z6u22EtjTAzp3bBjeC57Qq13jRFFmO/1EE+HsFmgUahecgN9jOAuc NH/6/JTEc/CAx1oMivPKLCIiiWMsea4Y4u9XIWuZMbRMa8Gsjcil4a0rNGkv4B3SybNA I0Bxk2aLN+6Buh1N6TwL/OVFLICH3AxXpD9vmImJSWYYMw9rlrGJmvwkXawCBP9Ofp+L G+YAGn5CqkdaL45xvuRjT+gjJZmDpqQgYtPuax1+JA+k0kSJ/jvc7o5EuKIEQpqMrii7 5nIsi9ydjf9O0F/UHAIhjFfvzaGJAKi9PqAMlYAigf4JS9dsfs+CbuBxEJXghpahd5YJ H1dQ== X-Gm-Message-State: APf1xPA3rLYFqzRde1FKI3Qy838KbRIIgyeWBX71S+PHC6Yf5A8qXbQH ll/zj60ZyPQXiqCqDnuIt9zmbA== X-Google-Smtp-Source: AH8x227I31bID5Y34ljArxOf3c4WKSwwXWgn3S3IAKCMr9z5TQoVYaRI15+U4tI+DM7kBrTeJTm3MQ== X-Received: by 2002:a17:902:6f17:: with SMTP id w23-v6mr182699plk.336.1518638813995; Wed, 14 Feb 2018 12:06:53 -0800 (PST) From: Kees Cook To: Andrew Morton Cc: Kees Cook , Linus Torvalds , Michal Hocko , Ben Hutchings , Willy Tarreau , Hugh Dickins , Oleg Nesterov , "Jason A. Donenfeld" , Rik van Riel , Laura Abbott , Greg KH , Andy Lutomirski , linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: [PATCH 2/3] exec: Introduce finalize_exec() before start_thread() Date: Wed, 14 Feb 2018 12:06:35 -0800 Message-Id: <1518638796-20819-3-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1518638796-20819-1-git-send-email-keescook@chromium.org> References: <1518638796-20819-1-git-send-email-keescook@chromium.org> X-Virus-Scanned: ClamAV using ClamSMTP Provide a final call back into fs/exec.c before start_thread() takes over, to handle any last-minute changes, like the coming restoration of the stack limit. Signed-off-by: Kees Cook --- As an alternative, fs/exec.c could provide a wrapper for start_thread()... --- fs/binfmt_aout.c | 1 + fs/binfmt_elf.c | 1 + fs/binfmt_elf_fdpic.c | 1 + fs/binfmt_flat.c | 1 + fs/exec.c | 6 ++++++ include/linux/binfmts.h | 1 + 6 files changed, 11 insertions(+) diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c index ce1824f47ba6..c3deb2e35f20 100644 --- a/fs/binfmt_aout.c +++ b/fs/binfmt_aout.c @@ -330,6 +330,7 @@ static int load_aout_binary(struct linux_binprm * bprm) #ifdef __alpha__ regs->gp = ex.a_gpvalue; #endif + finalize_exec(bprm); start_thread(regs, ex.a_entry, current->mm->start_stack); return 0; } diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index bdb201230bae..3edca6cb9a33 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1155,6 +1155,7 @@ static int load_elf_binary(struct linux_binprm *bprm) ELF_PLAT_INIT(regs, reloc_func_desc); #endif + finalize_exec(bprm); start_thread(regs, elf_entry, bprm->p); retval = 0; out: diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c index 429326b6e2e7..d90993adeffa 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -463,6 +463,7 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm) dynaddr); #endif + finalize_exec(bprm); /* everything is now ready... get the userspace context ready to roll */ entryaddr = interp_params.entry_addr ?: exec_params.entry_addr; start_thread(regs, entryaddr, current->mm->start_stack); diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c index 5d6b94475f27..82a48e830018 100644 --- a/fs/binfmt_flat.c +++ b/fs/binfmt_flat.c @@ -994,6 +994,7 @@ static int load_flat_binary(struct linux_binprm *bprm) FLAT_PLAT_INIT(regs); #endif + finalize_exec(bprm); pr_debug("start_thread(regs=0x%p, entry=0x%lx, start_stack=0x%lx)\n", regs, start_addr, current->mm->start_stack); start_thread(regs, start_addr, current->mm->start_stack); diff --git a/fs/exec.c b/fs/exec.c index 7074913ad2e7..e4ae20ff6278 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1384,6 +1384,12 @@ void setup_new_exec(struct linux_binprm * bprm) } EXPORT_SYMBOL(setup_new_exec); +/* Runs immediately before start_thread() takes over. */ +void finalize_exec(struct linux_binprm *bprm) +{ +} +EXPORT_SYMBOL(finalize_exec); + /* * Prepare credentials and lock ->cred_guard_mutex. * install_exec_creds() commits the new creds and drops the lock. diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h index b0abe21d6cc9..40e52afbb2b0 100644 --- a/include/linux/binfmts.h +++ b/include/linux/binfmts.h @@ -118,6 +118,7 @@ extern int __must_check remove_arg_zero(struct linux_binprm *); extern int search_binary_handler(struct linux_binprm *); extern int flush_old_exec(struct linux_binprm * bprm); extern void setup_new_exec(struct linux_binprm * bprm); +extern void finalize_exec(struct linux_binprm *bprm); extern void would_dump(struct linux_binprm *, struct file *); extern int suid_dumpable;