From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook 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> References: <1518638796-20819-1-git-send-email-keescook@chromium.org> Return-path: Received: from mail-pl0-f65.google.com ([209.85.160.65]:34950 "EHLO mail-pl0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031005AbeBNUGy (ORCPT ); Wed, 14 Feb 2018 15:06:54 -0500 Received: by mail-pl0-f65.google.com with SMTP id o11so5512942pls.2 for ; Wed, 14 Feb 2018 12:06:54 -0800 (PST) In-Reply-To: <1518638796-20819-1-git-send-email-keescook@chromium.org> Sender: linux-arch-owner@vger.kernel.org List-ID: 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 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; -- 2.7.4