Commit 71fe97e1 authored by Cyrill Gorcunov's avatar Cyrill Gorcunov Committed by Linus Torvalds
Browse files

prctl: PR_SET_MM -- factor out mmap_sem when updating mm::exe_file 



Instead of taking mm->mmap_sem inside prctl_set_mm_exe_file() move it out
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: default avatarCyrill Gorcunov <gorcunov@openvz.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Acked-by: default avatarSerge Hallyn <serge.hallyn@canonical.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Julien Tinnes <jln@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8764b338

kernel/sys.c

+11 −10
Original line number Diff line number Diff line
@@ -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 mm_struct *mm, unsigned int fd) 
	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 mm_struct *mm, unsigned int fd) 
			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 mm_struct *mm, unsigned int fd) 
	 */

	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;
@@ -1703,8 +1700,12 @@ static int prctl_set_mm(int opt, unsigned long addr, 
	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;

CRA Git | Maintained and supported by SUSTech CRA and CCSE