From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758377Ab2CHQvU (ORCPT ); Thu, 8 Mar 2012 11:51:20 -0500 Received: from mail-bk0-f46.google.com ([209.85.214.46]:49483 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758114Ab2CHQvS (ORCPT ); Thu, 8 Mar 2012 11:51:18 -0500 Date: Thu, 8 Mar 2012 20:51:12 +0400 From: Cyrill Gorcunov To: Oleg Nesterov Cc: KOSAKI Motohiro , Pavel Emelyanov , Kees Cook , Tejun Heo , Andrew Morton , LKML Subject: [RFC] c/r: prctl: Add ability to set new mm_struct::exe_file v3 Message-ID: <20120308165112.GF21812@moon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Oleg, could you please take a look once you get a minute (no urgency). Cyrill --- From: Cyrill Gorcunov Subject: c/r: prctl: Add ability to set new mm_struct::exe_file v3 When we do restore we would like to have a way to setup a former mm_struct::exe_file so that /proc/pid/exe would point to the original executable file a process had at checkpoint time. For this the PR_SET_MM_EXE_FILE code is introduced. This option takes a file descriptor which will be set as new /proc/$pid/exe symlink. This feature is available iif CONFIG_CHECKPOINT_RESTORE is set. Signed-off-by: Cyrill Gorcunov CC: Oleg Nesterov CC: KOSAKI Motohiro CC: Pavel Emelyanov CC: Kees Cook CC: Tejun Heo --- include/linux/prctl.h | 1 + kernel/sys.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 51 insertions(+) Index: linux-2.6.git/include/linux/prctl.h =================================================================== --- linux-2.6.git.orig/include/linux/prctl.h +++ linux-2.6.git/include/linux/prctl.h @@ -118,5 +118,6 @@ # define PR_SET_MM_ENV_START 10 # define PR_SET_MM_ENV_END 11 # define PR_SET_MM_AUXV 12 +# define PR_SET_MM_EXE_FILE 13 #endif /* _LINUX_PRCTL_H */ Index: linux-2.6.git/kernel/sys.c =================================================================== --- linux-2.6.git.orig/kernel/sys.c +++ linux-2.6.git/kernel/sys.c @@ -36,6 +36,8 @@ #include #include #include +#include +#include #include #include #include @@ -1701,6 +1703,50 @@ static bool vma_flags_mismatch(struct vm (vma->vm_flags & banned); } +static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd) +{ + struct file *exe_file; + struct dentry *dentry; + int err; + + exe_file = fget(fd); + if (!exe_file) + return -EBADF; + + dentry = exe_file->f_path.dentry; + + /* + * Because the original mm->exe_file + * points to executable file, make sure + * this one is executable as well to not + * break "big" picture and proc/pid/exe + * symlink will be still pointing to + * executable one. + */ + err = -EACCES; + if (!S_ISREG(dentry->d_inode->i_mode) || + exe_file->f_path.mnt->mnt_flags & MNT_NOEXEC) + goto exit; + + err = inode_permission(dentry->d_inode, MAY_EXEC); + if (err) + goto exit; + + down_write(&mm->mmap_sem); + if (mm->num_exe_file_vmas) { + fput(mm->exe_file); + mm->exe_file = exe_file; + exe_file = NULL; + } else + set_mm_exe_file(mm, exe_file); + up_write(&mm->mmap_sem); + +exit: + if (exe_file) + fput(exe_file); + return err; +} + static int prctl_set_mm(int opt, unsigned long addr, unsigned long arg4, unsigned long arg5) { @@ -1715,6 +1761,9 @@ 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 (addr >= TASK_SIZE) return -EINVAL; @@ -1837,6 +1886,7 @@ static int prctl_set_mm(int opt, unsigne return 0; } + default: error = -EINVAL; goto out;