From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759117AbaGCPLJ (ORCPT ); Thu, 3 Jul 2014 11:11:09 -0400 Received: from mail-lb0-f176.google.com ([209.85.217.176]:61257 "EHLO mail-lb0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755678AbaGCPLG (ORCPT ); Thu, 3 Jul 2014 11:11:06 -0400 Message-Id: <20140703151102.745184283@openvz.org> User-Agent: quilt/0.60-1 Date: Thu, 03 Jul 2014 18:33:19 +0400 From: Cyrill Gorcunov To: linux-kernel@vger.kernel.org Cc: gorcunov@openvz.org, Kees Cook , Tejun Heo , Andrew Morton , Andrew Vagin , "Eric W. Biederman" , Serge Hallyn , Pavel Emelyanov , Vasiliy Kulikov , KAMEZAWA Hiroyuki , Michael Kerrisk Subject: [RFC 1/2] prctl: PR_SET_MM -- Factor out mmap_sem when update mm::exe_file References: <20140703143318.568554771@openvz.org> Content-Disposition: inline; filename=prctl-rework-prctl_set_mm_exe_file-locked Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Instead of taking mm->mmap_sem inside prctl_set_mm_exe_file move it out of and rename the helper to prctl_set_mm_exe_file_locked. This will allow to reuse this function in a next patch. Signed-off-by: Cyrill Gorcunov Cc: Kees Cook Cc: Tejun Heo Cc: Andrew Morton Cc: Andrew Vagin Cc: Eric W. Biederman Cc: Serge Hallyn Cc: Pavel Emelyanov Cc: Vasiliy Kulikov Cc: KAMEZAWA Hiroyuki Cc: Michael Kerrisk --- kernel/sys.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) Index: linux-2.6.git/kernel/sys.c =================================================================== --- linux-2.6.git.orig/kernel/sys.c +++ linux-2.6.git/kernel/sys.c @@ -1628,12 +1628,14 @@ SYSCALL_DEFINE1(umask, int, mask) return mask; } -static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd) +static int prctl_set_mm_exe_file_locked(struct mm_struct *mm, unsigned int fd) { struct fd exe; struct inode *inode; int err; + VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); + exe = fdget(fd); if (!exe.file) return -EBADF; @@ -1654,8 +1656,6 @@ static int prctl_set_mm_exe_file(struct if (err) goto exit; - down_write(&mm->mmap_sem); - /* * Forbid mm->exe_file change if old file still mapped. */ @@ -1667,7 +1667,7 @@ static int prctl_set_mm_exe_file(struct if (vma->vm_file && path_equal(&vma->vm_file->f_path, &mm->exe_file->f_path)) - goto exit_unlock; + goto exit; } /* @@ -1678,13 +1678,10 @@ static int prctl_set_mm_exe_file(struct */ err = -EPERM; if (test_and_set_bit(MMF_EXE_FILE_CHANGED, &mm->flags)) - goto exit_unlock; + goto exit; err = 0; set_mm_exe_file(mm, exe.file); /* this grabs a reference to exe.file */ -exit_unlock: - up_write(&mm->mmap_sem); - exit: fdput(exe); return err; @@ -1704,8 +1701,12 @@ static int prctl_set_mm(int opt, unsigne if (!capable(CAP_SYS_RESOURCE)) return -EPERM; - if (opt == PR_SET_MM_EXE_FILE) - return prctl_set_mm_exe_file(mm, (unsigned int)addr); + if (opt == PR_SET_MM_EXE_FILE) { + down_write(&mm->mmap_sem); + error = prctl_set_mm_exe_file_locked(mm, (unsigned int)addr); + up_write(&mm->mmap_sem); + return error; + } if (addr >= TASK_SIZE || addr < mmap_min_addr) return -EINVAL;