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Message-Id: <20180412150826.20988-28-mszeredi@redhat.com>
Date: Thu, 12 Apr 2018 17:08:18 +0200
From: Miklos Szeredi <mszeredi@...hat.com>
To: linux-unionfs@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH 27/35] Revert "ovl: don't allow writing ioctl on lower layer"
This reverts commit 7c6893e3c9abf6a9676e060a1e35e5caca673d57.
Overlayfs no longer relies on the vfs for checking writability of files.
Signed-off-by: Miklos Szeredi <mszeredi@...hat.com>
---
fs/internal.h | 2 --
fs/namespace.c | 64 +++-------------------------------------------------------
fs/open.c | 4 ++--
fs/xattr.c | 9 ++++-----
4 files changed, 9 insertions(+), 70 deletions(-)
diff --git a/fs/internal.h b/fs/internal.h
index f0eaa33890d9..d7fdd56bafd3 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -72,10 +72,8 @@ extern void __init mnt_init(void);
extern int __mnt_want_write(struct vfsmount *);
extern int __mnt_want_write_file(struct file *);
-extern int mnt_want_write_file_path(struct file *);
extern void __mnt_drop_write(struct vfsmount *);
extern void __mnt_drop_write_file(struct file *);
-extern void mnt_drop_write_file_path(struct file *);
/*
* fs_struct.c
diff --git a/fs/namespace.c b/fs/namespace.c
index 9ec9bf74116b..e2645ef331f2 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -431,18 +431,13 @@ int __mnt_want_write_file(struct file *file)
}
/**
- * mnt_want_write_file_path - get write access to a file's mount
+ * mnt_want_write_file - get write access to a file's mount
* @file: the file who's mount on which to take a write
*
* This is like mnt_want_write, but it takes a file and can
* do some optimisations if the file is open for write already
- *
- * Called by the vfs for cases when we have an open file at hand, but will do an
- * inode operation on it (important distinction for files opened on overlayfs,
- * since the file operations will come from the real underlying file, while
- * inode operations come from the overlay).
*/
-int mnt_want_write_file_path(struct file *file)
+int mnt_want_write_file(struct file *file)
{
int ret;
@@ -452,53 +447,6 @@ int mnt_want_write_file_path(struct file *file)
sb_end_write(file->f_path.mnt->mnt_sb);
return ret;
}
-
-static inline int may_write_real(struct file *file)
-{
- struct dentry *dentry = file->f_path.dentry;
- struct dentry *upperdentry;
-
- /* Writable file? */
- if (file->f_mode & FMODE_WRITER)
- return 0;
-
- /* Not overlayfs? */
- if (likely(!(dentry->d_flags & DCACHE_OP_REAL)))
- return 0;
-
- /* File refers to upper, writable layer? */
- upperdentry = d_real(dentry, NULL, 0, D_REAL_UPPER);
- if (upperdentry && file_inode(file) == d_inode(upperdentry))
- return 0;
-
- /* Lower layer: can't write to real file, sorry... */
- return -EPERM;
-}
-
-/**
- * mnt_want_write_file - get write access to a file's mount
- * @file: the file who's mount on which to take a write
- *
- * This is like mnt_want_write, but it takes a file and can
- * do some optimisations if the file is open for write already
- *
- * Mostly called by filesystems from their ioctl operation before performing
- * modification. On overlayfs this needs to check if the file is on a read-only
- * lower layer and deny access in that case.
- */
-int mnt_want_write_file(struct file *file)
-{
- int ret;
-
- ret = may_write_real(file);
- if (!ret) {
- sb_start_write(file_inode(file)->i_sb);
- ret = __mnt_want_write_file(file);
- if (ret)
- sb_end_write(file_inode(file)->i_sb);
- }
- return ret;
-}
EXPORT_SYMBOL_GPL(mnt_want_write_file);
/**
@@ -536,15 +484,9 @@ void __mnt_drop_write_file(struct file *file)
__mnt_drop_write(file->f_path.mnt);
}
-void mnt_drop_write_file_path(struct file *file)
-{
- mnt_drop_write(file->f_path.mnt);
-}
-
void mnt_drop_write_file(struct file *file)
{
- __mnt_drop_write(file->f_path.mnt);
- sb_end_write(file_inode(file)->i_sb);
+ mnt_drop_write(file->f_path.mnt);
}
EXPORT_SYMBOL(mnt_drop_write_file);
diff --git a/fs/open.c b/fs/open.c
index 442088ca30f9..00b1f18475ba 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -670,12 +670,12 @@ SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
if (!f.file)
goto out;
- error = mnt_want_write_file_path(f.file);
+ error = mnt_want_write_file(f.file);
if (error)
goto out_fput;
audit_file(f.file);
error = chown_common(&f.file->f_path, user, group);
- mnt_drop_write_file_path(f.file);
+ mnt_drop_write_file(f.file);
out_fput:
fdput(f);
out:
diff --git a/fs/xattr.c b/fs/xattr.c
index 61cd28ba25f3..78eaffbdbee0 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -23,7 +23,6 @@
#include <linux/posix_acl_xattr.h>
#include <linux/uaccess.h>
-#include "internal.h"
static const char *
strcmp_prefix(const char *a, const char *a_prefix)
@@ -503,10 +502,10 @@ SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
if (!f.file)
return error;
audit_file(f.file);
- error = mnt_want_write_file_path(f.file);
+ error = mnt_want_write_file(f.file);
if (!error) {
error = setxattr(f.file->f_path.dentry, name, value, size, flags);
- mnt_drop_write_file_path(f.file);
+ mnt_drop_write_file(f.file);
}
fdput(f);
return error;
@@ -735,10 +734,10 @@ SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
if (!f.file)
return error;
audit_file(f.file);
- error = mnt_want_write_file_path(f.file);
+ error = mnt_want_write_file(f.file);
if (!error) {
error = removexattr(f.file->f_path.dentry, name);
- mnt_drop_write_file_path(f.file);
+ mnt_drop_write_file(f.file);
}
fdput(f);
return error;
--
2.14.3
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