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3231 lines
81 KiB
3231 lines
81 KiB
--- a/Documentation/filesystems/Locking
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+++ b/Documentation/filesystems/Locking
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@@ -65,6 +65,7 @@ prototypes:
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struct file *, unsigned open_flag,
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umode_t create_mode, int *opened);
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int (*tmpfile) (struct inode *, struct dentry *, umode_t);
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+ int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
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|
|
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locking rules:
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all may block
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@@ -93,6 +94,7 @@ fiemap: no
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update_time: no
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atomic_open: yes
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tmpfile: no
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+dentry_open: no
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Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on
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victim.
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--- /dev/null
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+++ b/Documentation/filesystems/overlayfs.txt
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@@ -0,0 +1,199 @@
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+Written by: Neil Brown <neilb@suse.de>
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+
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+Overlay Filesystem
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+==================
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+
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+This document describes a prototype for a new approach to providing
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+overlay-filesystem functionality in Linux (sometimes referred to as
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+union-filesystems). An overlay-filesystem tries to present a
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+filesystem which is the result over overlaying one filesystem on top
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+of the other.
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+
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+The result will inevitably fail to look exactly like a normal
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+filesystem for various technical reasons. The expectation is that
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+many use cases will be able to ignore these differences.
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+
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+This approach is 'hybrid' because the objects that appear in the
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+filesystem do not all appear to belong to that filesystem. In many
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+cases an object accessed in the union will be indistinguishable
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+from accessing the corresponding object from the original filesystem.
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+This is most obvious from the 'st_dev' field returned by stat(2).
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+
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+While directories will report an st_dev from the overlay-filesystem,
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+all non-directory objects will report an st_dev from the lower or
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+upper filesystem that is providing the object. Similarly st_ino will
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+only be unique when combined with st_dev, and both of these can change
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+over the lifetime of a non-directory object. Many applications and
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+tools ignore these values and will not be affected.
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+
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+Upper and Lower
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+---------------
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+
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+An overlay filesystem combines two filesystems - an 'upper' filesystem
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+and a 'lower' filesystem. When a name exists in both filesystems, the
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+object in the 'upper' filesystem is visible while the object in the
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+'lower' filesystem is either hidden or, in the case of directories,
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+merged with the 'upper' object.
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+
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+It would be more correct to refer to an upper and lower 'directory
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+tree' rather than 'filesystem' as it is quite possible for both
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+directory trees to be in the same filesystem and there is no
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+requirement that the root of a filesystem be given for either upper or
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+lower.
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+
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+The lower filesystem can be any filesystem supported by Linux and does
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+not need to be writable. The lower filesystem can even be another
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+overlayfs. The upper filesystem will normally be writable and if it
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+is it must support the creation of trusted.* extended attributes, and
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+must provide valid d_type in readdir responses, at least for symbolic
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+links - so NFS is not suitable.
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+
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+A read-only overlay of two read-only filesystems may use any
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+filesystem type.
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+
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+Directories
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+-----------
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+
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+Overlaying mainly involves directories. If a given name appears in both
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+upper and lower filesystems and refers to a non-directory in either,
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+then the lower object is hidden - the name refers only to the upper
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+object.
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+
|
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+Where both upper and lower objects are directories, a merged directory
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|
+is formed.
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+
|
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+At mount time, the two directories given as mount options are combined
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+into a merged directory:
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+
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+ mount -t overlayfs overlayfs -olowerdir=/lower,upperdir=/upper /overlay
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+
|
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+Then whenever a lookup is requested in such a merged directory, the
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+lookup is performed in each actual directory and the combined result
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|
+is cached in the dentry belonging to the overlay filesystem. If both
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|
+actual lookups find directories, both are stored and a merged
|
|
+directory is created, otherwise only one is stored: the upper if it
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|
+exists, else the lower.
|
|
+
|
|
+Only the lists of names from directories are merged. Other content
|
|
+such as metadata and extended attributes are reported for the upper
|
|
+directory only. These attributes of the lower directory are hidden.
|
|
+
|
|
+whiteouts and opaque directories
|
|
+--------------------------------
|
|
+
|
|
+In order to support rm and rmdir without changing the lower
|
|
+filesystem, an overlay filesystem needs to record in the upper filesystem
|
|
+that files have been removed. This is done using whiteouts and opaque
|
|
+directories (non-directories are always opaque).
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|
+
|
|
+The overlay filesystem uses extended attributes with a
|
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+"trusted.overlay." prefix to record these details.
|
|
+
|
|
+A whiteout is created as a symbolic link with target
|
|
+"(overlay-whiteout)" and with xattr "trusted.overlay.whiteout" set to "y".
|
|
+When a whiteout is found in the upper level of a merged directory, any
|
|
+matching name in the lower level is ignored, and the whiteout itself
|
|
+is also hidden.
|
|
+
|
|
+A directory is made opaque by setting the xattr "trusted.overlay.opaque"
|
|
+to "y". Where the upper filesystem contains an opaque directory, any
|
|
+directory in the lower filesystem with the same name is ignored.
|
|
+
|
|
+readdir
|
|
+-------
|
|
+
|
|
+When a 'readdir' request is made on a merged directory, the upper and
|
|
+lower directories are each read and the name lists merged in the
|
|
+obvious way (upper is read first, then lower - entries that already
|
|
+exist are not re-added). This merged name list is cached in the
|
|
+'struct file' and so remains as long as the file is kept open. If the
|
|
+directory is opened and read by two processes at the same time, they
|
|
+will each have separate caches. A seekdir to the start of the
|
|
+directory (offset 0) followed by a readdir will cause the cache to be
|
|
+discarded and rebuilt.
|
|
+
|
|
+This means that changes to the merged directory do not appear while a
|
|
+directory is being read. This is unlikely to be noticed by many
|
|
+programs.
|
|
+
|
|
+seek offsets are assigned sequentially when the directories are read.
|
|
+Thus if
|
|
+ - read part of a directory
|
|
+ - remember an offset, and close the directory
|
|
+ - re-open the directory some time later
|
|
+ - seek to the remembered offset
|
|
+
|
|
+there may be little correlation between the old and new locations in
|
|
+the list of filenames, particularly if anything has changed in the
|
|
+directory.
|
|
+
|
|
+Readdir on directories that are not merged is simply handled by the
|
|
+underlying directory (upper or lower).
|
|
+
|
|
+
|
|
+Non-directories
|
|
+---------------
|
|
+
|
|
+Objects that are not directories (files, symlinks, device-special
|
|
+files etc.) are presented either from the upper or lower filesystem as
|
|
+appropriate. When a file in the lower filesystem is accessed in a way
|
|
+the requires write-access, such as opening for write access, changing
|
|
+some metadata etc., the file is first copied from the lower filesystem
|
|
+to the upper filesystem (copy_up). Note that creating a hard-link
|
|
+also requires copy_up, though of course creation of a symlink does
|
|
+not.
|
|
+
|
|
+The copy_up may turn out to be unnecessary, for example if the file is
|
|
+opened for read-write but the data is not modified.
|
|
+
|
|
+The copy_up process first makes sure that the containing directory
|
|
+exists in the upper filesystem - creating it and any parents as
|
|
+necessary. It then creates the object with the same metadata (owner,
|
|
+mode, mtime, symlink-target etc.) and then if the object is a file, the
|
|
+data is copied from the lower to the upper filesystem. Finally any
|
|
+extended attributes are copied up.
|
|
+
|
|
+Once the copy_up is complete, the overlay filesystem simply
|
|
+provides direct access to the newly created file in the upper
|
|
+filesystem - future operations on the file are barely noticed by the
|
|
+overlay filesystem (though an operation on the name of the file such as
|
|
+rename or unlink will of course be noticed and handled).
|
|
+
|
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+
|
|
+Non-standard behavior
|
|
+---------------------
|
|
+
|
|
+The copy_up operation essentially creates a new, identical file and
|
|
+moves it over to the old name. The new file may be on a different
|
|
+filesystem, so both st_dev and st_ino of the file may change.
|
|
+
|
|
+Any open files referring to this inode will access the old data and
|
|
+metadata. Similarly any file locks obtained before copy_up will not
|
|
+apply to the copied up file.
|
|
+
|
|
+On a file opened with O_RDONLY fchmod(2), fchown(2), futimesat(2) and
|
|
+fsetxattr(2) will fail with EROFS.
|
|
+
|
|
+If a file with multiple hard links is copied up, then this will
|
|
+"break" the link. Changes will not be propagated to other names
|
|
+referring to the same inode.
|
|
+
|
|
+Symlinks in /proc/PID/ and /proc/PID/fd which point to a non-directory
|
|
+object in overlayfs will not contain valid absolute paths, only
|
|
+relative paths leading up to the filesystem's root. This will be
|
|
+fixed in the future.
|
|
+
|
|
+Some operations are not atomic, for example a crash during copy_up or
|
|
+rename will leave the filesystem in an inconsistent state. This will
|
|
+be addressed in the future.
|
|
+
|
|
+Changes to underlying filesystems
|
|
+---------------------------------
|
|
+
|
|
+Offline changes, when the overlay is not mounted, are allowed to either
|
|
+the upper or the lower trees.
|
|
+
|
|
+Changes to the underlying filesystems while part of a mounted overlay
|
|
+filesystem are not allowed. If the underlying filesystem is changed,
|
|
+the behavior of the overlay is undefined, though it will not result in
|
|
+a crash or deadlock.
|
|
--- a/Documentation/filesystems/vfs.txt
|
|
+++ b/Documentation/filesystems/vfs.txt
|
|
@@ -362,6 +362,7 @@ struct inode_operations {
|
|
int (*atomic_open)(struct inode *, struct dentry *, struct file *,
|
|
unsigned open_flag, umode_t create_mode, int *opened);
|
|
int (*tmpfile) (struct inode *, struct dentry *, umode_t);
|
|
+ int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
|
|
};
|
|
|
|
Again, all methods are called without any locks being held, unless
|
|
@@ -681,6 +682,12 @@ struct address_space_operations {
|
|
but instead uses bmap to find out where the blocks in the file
|
|
are and uses those addresses directly.
|
|
|
|
+ dentry_open: this is an alternative to f_op->open(), the difference is that
|
|
+ this method may open a file not necessarily originating from the same
|
|
+ filesystem as the one i_op->open() was called on. It may be
|
|
+ useful for stacking filesystems which want to allow native I/O directly
|
|
+ on underlying files.
|
|
+
|
|
|
|
invalidatepage: If a page has PagePrivate set, then invalidatepage
|
|
will be called when part or all of the page is to be removed
|
|
--- a/MAINTAINERS
|
|
+++ b/MAINTAINERS
|
|
@@ -6452,6 +6452,13 @@ F: drivers/scsi/osd/
|
|
F: include/scsi/osd_*
|
|
F: fs/exofs/
|
|
|
|
+OVERLAYFS FILESYSTEM
|
|
+M: Miklos Szeredi <miklos@szeredi.hu>
|
|
+L: linux-fsdevel@vger.kernel.org
|
|
+S: Supported
|
|
+F: fs/overlayfs/*
|
|
+F: Documentation/filesystems/overlayfs.txt
|
|
+
|
|
P54 WIRELESS DRIVER
|
|
M: Christian Lamparter <chunkeey@googlemail.com>
|
|
L: linux-wireless@vger.kernel.org
|
|
--- a/fs/Kconfig
|
|
+++ b/fs/Kconfig
|
|
@@ -67,6 +67,7 @@ source "fs/quota/Kconfig"
|
|
|
|
source "fs/autofs4/Kconfig"
|
|
source "fs/fuse/Kconfig"
|
|
+source "fs/overlayfs/Kconfig"
|
|
|
|
menu "Caches"
|
|
|
|
--- a/fs/Makefile
|
|
+++ b/fs/Makefile
|
|
@@ -104,6 +104,7 @@ obj-$(CONFIG_QNX6FS_FS) += qnx6/
|
|
obj-$(CONFIG_AUTOFS4_FS) += autofs4/
|
|
obj-$(CONFIG_ADFS_FS) += adfs/
|
|
obj-$(CONFIG_FUSE_FS) += fuse/
|
|
+obj-$(CONFIG_OVERLAYFS_FS) += overlayfs/
|
|
obj-$(CONFIG_UDF_FS) += udf/
|
|
obj-$(CONFIG_SUN_OPENPROMFS) += openpromfs/
|
|
obj-$(CONFIG_OMFS_FS) += omfs/
|
|
--- a/fs/ecryptfs/main.c
|
|
+++ b/fs/ecryptfs/main.c
|
|
@@ -566,6 +566,13 @@ static struct dentry *ecryptfs_mount(str
|
|
s->s_maxbytes = path.dentry->d_sb->s_maxbytes;
|
|
s->s_blocksize = path.dentry->d_sb->s_blocksize;
|
|
s->s_magic = ECRYPTFS_SUPER_MAGIC;
|
|
+ s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1;
|
|
+
|
|
+ rc = -EINVAL;
|
|
+ if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
|
|
+ pr_err("eCryptfs: maximum fs stacking depth exceeded\n");
|
|
+ goto out_free;
|
|
+ }
|
|
|
|
inode = ecryptfs_get_inode(path.dentry->d_inode, s);
|
|
rc = PTR_ERR(inode);
|
|
--- a/fs/internal.h
|
|
+++ b/fs/internal.h
|
|
@@ -42,7 +42,6 @@ extern void __init chrdev_init(void);
|
|
/*
|
|
* namei.c
|
|
*/
|
|
-extern int __inode_permission(struct inode *, int);
|
|
extern int user_path_mountpoint_at(int, const char __user *, unsigned int, struct path *);
|
|
extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
|
|
const char *, unsigned int, struct path *);
|
|
@@ -135,12 +134,6 @@ extern ssize_t __kernel_write(struct fil
|
|
extern int rw_verify_area(int, struct file *, const loff_t *, size_t);
|
|
|
|
/*
|
|
- * splice.c
|
|
- */
|
|
-extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
|
|
- loff_t *opos, size_t len, unsigned int flags);
|
|
-
|
|
-/*
|
|
* pipe.c
|
|
*/
|
|
extern const struct file_operations pipefifo_fops;
|
|
--- a/fs/namei.c
|
|
+++ b/fs/namei.c
|
|
@@ -414,6 +414,7 @@ int __inode_permission(struct inode *ino
|
|
|
|
return security_inode_permission(inode, mask);
|
|
}
|
|
+EXPORT_SYMBOL(__inode_permission);
|
|
|
|
/**
|
|
* sb_permission - Check superblock-level permissions
|
|
@@ -3036,9 +3037,12 @@ finish_open_created:
|
|
error = may_open(&nd->path, acc_mode, open_flag);
|
|
if (error)
|
|
goto out;
|
|
- file->f_path.mnt = nd->path.mnt;
|
|
- error = finish_open(file, nd->path.dentry, NULL, opened);
|
|
- if (error) {
|
|
+
|
|
+ BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
|
|
+ error = vfs_open(&nd->path, file, current_cred());
|
|
+ if (!error) {
|
|
+ *opened |= FILE_OPENED;
|
|
+ } else {
|
|
if (error == -EOPENSTALE)
|
|
goto stale_open;
|
|
goto out;
|
|
--- a/fs/namespace.c
|
|
+++ b/fs/namespace.c
|
|
@@ -1541,6 +1541,33 @@ void drop_collected_mounts(struct vfsmou
|
|
namespace_unlock();
|
|
}
|
|
|
|
+/**
|
|
+ * clone_private_mount - create a private clone of a path
|
|
+ *
|
|
+ * This creates a new vfsmount, which will be the clone of @path. The new will
|
|
+ * not be attached anywhere in the namespace and will be private (i.e. changes
|
|
+ * to the originating mount won't be propagated into this).
|
|
+ *
|
|
+ * Release with mntput().
|
|
+ */
|
|
+struct vfsmount *clone_private_mount(struct path *path)
|
|
+{
|
|
+ struct mount *old_mnt = real_mount(path->mnt);
|
|
+ struct mount *new_mnt;
|
|
+
|
|
+ if (IS_MNT_UNBINDABLE(old_mnt))
|
|
+ return ERR_PTR(-EINVAL);
|
|
+
|
|
+ down_read(&namespace_sem);
|
|
+ new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE);
|
|
+ up_read(&namespace_sem);
|
|
+ if (IS_ERR(new_mnt))
|
|
+ return ERR_CAST(new_mnt);
|
|
+
|
|
+ return &new_mnt->mnt;
|
|
+}
|
|
+EXPORT_SYMBOL_GPL(clone_private_mount);
|
|
+
|
|
int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg,
|
|
struct vfsmount *root)
|
|
{
|
|
--- a/fs/open.c
|
|
+++ b/fs/open.c
|
|
@@ -822,8 +822,7 @@ struct file *dentry_open(const struct pa
|
|
f = get_empty_filp();
|
|
if (!IS_ERR(f)) {
|
|
f->f_flags = flags;
|
|
- f->f_path = *path;
|
|
- error = do_dentry_open(f, NULL, cred);
|
|
+ error = vfs_open(path, f, cred);
|
|
if (!error) {
|
|
/* from now on we need fput() to dispose of f */
|
|
error = open_check_o_direct(f);
|
|
@@ -840,6 +839,26 @@ struct file *dentry_open(const struct pa
|
|
}
|
|
EXPORT_SYMBOL(dentry_open);
|
|
|
|
+/**
|
|
+ * vfs_open - open the file at the given path
|
|
+ * @path: path to open
|
|
+ * @filp: newly allocated file with f_flag initialized
|
|
+ * @cred: credentials to use
|
|
+ */
|
|
+int vfs_open(const struct path *path, struct file *filp,
|
|
+ const struct cred *cred)
|
|
+{
|
|
+ struct inode *inode = path->dentry->d_inode;
|
|
+
|
|
+ if (inode->i_op->dentry_open)
|
|
+ return inode->i_op->dentry_open(path->dentry, filp, cred);
|
|
+ else {
|
|
+ filp->f_path = *path;
|
|
+ return do_dentry_open(filp, NULL, cred);
|
|
+ }
|
|
+}
|
|
+EXPORT_SYMBOL(vfs_open);
|
|
+
|
|
static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
|
|
{
|
|
int lookup_flags = 0;
|
|
--- /dev/null
|
|
+++ b/fs/overlayfs/Kconfig
|
|
@@ -0,0 +1,10 @@
|
|
+config OVERLAYFS_FS
|
|
+ tristate "Overlay filesystem support"
|
|
+ help
|
|
+ An overlay filesystem combines two filesystems - an 'upper' filesystem
|
|
+ and a 'lower' filesystem. When a name exists in both filesystems, the
|
|
+ object in the 'upper' filesystem is visible while the object in the
|
|
+ 'lower' filesystem is either hidden or, in the case of directories,
|
|
+ merged with the 'upper' object.
|
|
+
|
|
+ For more information see Documentation/filesystems/overlayfs.txt
|
|
--- /dev/null
|
|
+++ b/fs/overlayfs/Makefile
|
|
@@ -0,0 +1,7 @@
|
|
+#
|
|
+# Makefile for the overlay filesystem.
|
|
+#
|
|
+
|
|
+obj-$(CONFIG_OVERLAYFS_FS) += overlayfs.o
|
|
+
|
|
+overlayfs-objs := super.o inode.o dir.o readdir.o copy_up.o
|
|
--- /dev/null
|
|
+++ b/fs/overlayfs/copy_up.c
|
|
@@ -0,0 +1,388 @@
|
|
+/*
|
|
+ *
|
|
+ * Copyright (C) 2011 Novell Inc.
|
|
+ *
|
|
+ * This program is free software; you can redistribute it and/or modify it
|
|
+ * under the terms of the GNU General Public License version 2 as published by
|
|
+ * the Free Software Foundation.
|
|
+ */
|
|
+
|
|
+#include <linux/fs.h>
|
|
+#include <linux/slab.h>
|
|
+#include <linux/file.h>
|
|
+#include <linux/splice.h>
|
|
+#include <linux/xattr.h>
|
|
+#include <linux/security.h>
|
|
+#include <linux/uaccess.h>
|
|
+#include <linux/sched.h>
|
|
+#include "overlayfs.h"
|
|
+
|
|
+#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
|
|
+
|
|
+static int ovl_copy_up_xattr(struct dentry *old, struct dentry *new)
|
|
+{
|
|
+ ssize_t list_size, size;
|
|
+ char *buf, *name, *value;
|
|
+ int error;
|
|
+
|
|
+ if (!old->d_inode->i_op->getxattr ||
|
|
+ !new->d_inode->i_op->getxattr)
|
|
+ return 0;
|
|
+
|
|
+ list_size = vfs_listxattr(old, NULL, 0);
|
|
+ if (list_size <= 0) {
|
|
+ if (list_size == -EOPNOTSUPP)
|
|
+ return 0;
|
|
+ return list_size;
|
|
+ }
|
|
+
|
|
+ buf = kzalloc(list_size, GFP_KERNEL);
|
|
+ if (!buf)
|
|
+ return -ENOMEM;
|
|
+
|
|
+ error = -ENOMEM;
|
|
+ value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL);
|
|
+ if (!value)
|
|
+ goto out;
|
|
+
|
|
+ list_size = vfs_listxattr(old, buf, list_size);
|
|
+ if (list_size <= 0) {
|
|
+ error = list_size;
|
|
+ goto out_free_value;
|
|
+ }
|
|
+
|
|
+ for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
|
|
+ size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX);
|
|
+ if (size <= 0) {
|
|
+ error = size;
|
|
+ goto out_free_value;
|
|
+ }
|
|
+ error = vfs_setxattr(new, name, value, size, 0);
|
|
+ if (error)
|
|
+ goto out_free_value;
|
|
+ }
|
|
+
|
|
+out_free_value:
|
|
+ kfree(value);
|
|
+out:
|
|
+ kfree(buf);
|
|
+ return error;
|
|
+}
|
|
+
|
|
+static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
|
|
+{
|
|
+ struct file *old_file;
|
|
+ struct file *new_file;
|
|
+ loff_t old_pos = 0;
|
|
+ loff_t new_pos = 0;
|
|
+ int error = 0;
|
|
+
|
|
+ if (len == 0)
|
|
+ return 0;
|
|
+
|
|
+ old_file = ovl_path_open(old, O_RDONLY);
|
|
+ if (IS_ERR(old_file))
|
|
+ return PTR_ERR(old_file);
|
|
+
|
|
+ new_file = ovl_path_open(new, O_WRONLY);
|
|
+ if (IS_ERR(new_file)) {
|
|
+ error = PTR_ERR(new_file);
|
|
+ goto out_fput;
|
|
+ }
|
|
+
|
|
+ /* FIXME: copy up sparse files efficiently */
|
|
+ while (len) {
|
|
+ size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
|
|
+ long bytes;
|
|
+
|
|
+ if (len < this_len)
|
|
+ this_len = len;
|
|
+
|
|
+ if (signal_pending_state(TASK_KILLABLE, current)) {
|
|
+ error = -EINTR;
|
|
+ break;
|
|
+ }
|
|
+
|
|
+ bytes = do_splice_direct(old_file, &old_pos,
|
|
+ new_file, &new_pos,
|
|
+ this_len, SPLICE_F_MOVE);
|
|
+ if (bytes <= 0) {
|
|
+ error = bytes;
|
|
+ break;
|
|
+ }
|
|
+ WARN_ON(old_pos != new_pos);
|
|
+
|
|
+ len -= bytes;
|
|
+ }
|
|
+
|
|
+ fput(new_file);
|
|
+out_fput:
|
|
+ fput(old_file);
|
|
+ return error;
|
|
+}
|
|
+
|
|
+static char *ovl_read_symlink(struct dentry *realdentry)
|
|
+{
|
|
+ int res;
|
|
+ char *buf;
|
|
+ struct inode *inode = realdentry->d_inode;
|
|
+ mm_segment_t old_fs;
|
|
+
|
|
+ res = -EINVAL;
|
|
+ if (!inode->i_op->readlink)
|
|
+ goto err;
|
|
+
|
|
+ res = -ENOMEM;
|
|
+ buf = (char *) __get_free_page(GFP_KERNEL);
|
|
+ if (!buf)
|
|
+ goto err;
|
|
+
|
|
+ old_fs = get_fs();
|
|
+ set_fs(get_ds());
|
|
+ /* The cast to a user pointer is valid due to the set_fs() */
|
|
+ res = inode->i_op->readlink(realdentry,
|
|
+ (char __user *)buf, PAGE_SIZE - 1);
|
|
+ set_fs(old_fs);
|
|
+ if (res < 0) {
|
|
+ free_page((unsigned long) buf);
|
|
+ goto err;
|
|
+ }
|
|
+ buf[res] = '\0';
|
|
+
|
|
+ return buf;
|
|
+
|
|
+err:
|
|
+ return ERR_PTR(res);
|
|
+}
|
|
+
|
|
+static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
|
|
+{
|
|
+ struct iattr attr = {
|
|
+ .ia_valid =
|
|
+ ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
|
|
+ .ia_atime = stat->atime,
|
|
+ .ia_mtime = stat->mtime,
|
|
+ };
|
|
+
|
|
+ return notify_change(upperdentry, &attr, NULL);
|
|
+}
|
|
+
|
|
+static int ovl_set_mode(struct dentry *upperdentry, umode_t mode)
|
|
+{
|
|
+ struct iattr attr = {
|
|
+ .ia_valid = ATTR_MODE,
|
|
+ .ia_mode = mode,
|
|
+ };
|
|
+
|
|
+ return notify_change(upperdentry, &attr, NULL);
|
|
+}
|
|
+
|
|
+static int ovl_copy_up_locked(struct dentry *upperdir, struct dentry *dentry,
|
|
+ struct path *lowerpath, struct kstat *stat,
|
|
+ const char *link)
|
|
+{
|
|
+ int err;
|
|
+ struct path newpath;
|
|
+ umode_t mode = stat->mode;
|
|
+
|
|
+ /* Can't properly set mode on creation because of the umask */
|
|
+ stat->mode &= S_IFMT;
|
|
+
|
|
+ ovl_path_upper(dentry, &newpath);
|
|
+ WARN_ON(newpath.dentry);
|
|
+ newpath.dentry = ovl_upper_create(upperdir, dentry, stat, link);
|
|
+ if (IS_ERR(newpath.dentry))
|
|
+ return PTR_ERR(newpath.dentry);
|
|
+
|
|
+ if (S_ISREG(stat->mode)) {
|
|
+ err = ovl_copy_up_data(lowerpath, &newpath, stat->size);
|
|
+ if (err)
|
|
+ goto err_remove;
|
|
+ }
|
|
+
|
|
+ err = ovl_copy_up_xattr(lowerpath->dentry, newpath.dentry);
|
|
+ if (err)
|
|
+ goto err_remove;
|
|
+
|
|
+ mutex_lock(&newpath.dentry->d_inode->i_mutex);
|
|
+ if (!S_ISLNK(stat->mode))
|
|
+ err = ovl_set_mode(newpath.dentry, mode);
|
|
+ if (!err)
|
|
+ err = ovl_set_timestamps(newpath.dentry, stat);
|
|
+ mutex_unlock(&newpath.dentry->d_inode->i_mutex);
|
|
+ if (err)
|
|
+ goto err_remove;
|
|
+
|
|
+ ovl_dentry_update(dentry, newpath.dentry);
|
|
+
|
|
+ /*
|
|
+ * Easiest way to get rid of the lower dentry reference is to
|
|
+ * drop this dentry. This is neither needed nor possible for
|
|
+ * directories.
|
|
+ */
|
|
+ if (!S_ISDIR(stat->mode))
|
|
+ d_drop(dentry);
|
|
+
|
|
+ return 0;
|
|
+
|
|
+err_remove:
|
|
+ if (S_ISDIR(stat->mode))
|
|
+ vfs_rmdir(upperdir->d_inode, newpath.dentry);
|
|
+ else
|
|
+ vfs_unlink(upperdir->d_inode, newpath.dentry, NULL);
|
|
+
|
|
+ dput(newpath.dentry);
|
|
+
|
|
+ return err;
|
|
+}
|
|
+
|
|
+/*
|
|
+ * Copy up a single dentry
|
|
+ *
|
|
+ * Directory renames only allowed on "pure upper" (already created on
|
|
+ * upper filesystem, never copied up). Directories which are on lower or
|
|
+ * are merged may not be renamed. For these -EXDEV is returned and
|
|
+ * userspace has to deal with it. This means, when copying up a
|
|
+ * directory we can rely on it and ancestors being stable.
|
|
+ *
|
|
+ * Non-directory renames start with copy up of source if necessary. The
|
|
+ * actual rename will only proceed once the copy up was successful. Copy
|
|
+ * up uses upper parent i_mutex for exclusion. Since rename can change
|
|
+ * d_parent it is possible that the copy up will lock the old parent. At
|
|
+ * that point the file will have already been copied up anyway.
|
|
+ */
|
|
+static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
|
|
+ struct path *lowerpath, struct kstat *stat)
|
|
+{
|
|
+ int err;
|
|
+ struct kstat pstat;
|
|
+ struct path parentpath;
|
|
+ struct dentry *upperdir;
|
|
+ const struct cred *old_cred;
|
|
+ struct cred *override_cred;
|
|
+ char *link = NULL;
|
|
+
|
|
+ ovl_path_upper(parent, &parentpath);
|
|
+ upperdir = parentpath.dentry;
|
|
+
|
|
+ err = vfs_getattr(&parentpath, &pstat);
|
|
+ if (err)
|
|
+ return err;
|
|
+
|
|
+ if (S_ISLNK(stat->mode)) {
|
|
+ link = ovl_read_symlink(lowerpath->dentry);
|
|
+ if (IS_ERR(link))
|
|
+ return PTR_ERR(link);
|
|
+ }
|
|
+
|
|
+ err = -ENOMEM;
|
|
+ override_cred = prepare_creds();
|
|
+ if (!override_cred)
|
|
+ goto out_free_link;
|
|
+
|
|
+ override_cred->fsuid = stat->uid;
|
|
+ override_cred->fsgid = stat->gid;
|
|
+ /*
|
|
+ * CAP_SYS_ADMIN for copying up extended attributes
|
|
+ * CAP_DAC_OVERRIDE for create
|
|
+ * CAP_FOWNER for chmod, timestamp update
|
|
+ * CAP_FSETID for chmod
|
|
+ * CAP_MKNOD for mknod
|
|
+ */
|
|
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
|
|
+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
|
|
+ cap_raise(override_cred->cap_effective, CAP_FOWNER);
|
|
+ cap_raise(override_cred->cap_effective, CAP_FSETID);
|
|
+ cap_raise(override_cred->cap_effective, CAP_MKNOD);
|
|
+ old_cred = override_creds(override_cred);
|
|
+
|
|
+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
+ if (ovl_path_type(dentry) != OVL_PATH_LOWER) {
|
|
+ err = 0;
|
|
+ } else {
|
|
+ err = ovl_copy_up_locked(upperdir, dentry, lowerpath,
|
|
+ stat, link);
|
|
+ if (!err) {
|
|
+ /* Restore timestamps on parent (best effort) */
|
|
+ ovl_set_timestamps(upperdir, &pstat);
|
|
+ }
|
|
+ }
|
|
+
|
|
+ mutex_unlock(&upperdir->d_inode->i_mutex);
|
|
+
|
|
+ revert_creds(old_cred);
|
|
+ put_cred(override_cred);
|
|
+
|
|
+out_free_link:
|
|
+ if (link)
|
|
+ free_page((unsigned long) link);
|
|
+
|
|
+ return err;
|
|
+}
|
|
+
|
|
+int ovl_copy_up(struct dentry *dentry)
|
|
+{
|
|
+ int err;
|
|
+
|
|
+ err = 0;
|
|
+ while (!err) {
|
|
+ struct dentry *next;
|
|
+ struct dentry *parent;
|
|
+ struct path lowerpath;
|
|
+ struct kstat stat;
|
|
+ enum ovl_path_type type = ovl_path_type(dentry);
|
|
+
|
|
+ if (type != OVL_PATH_LOWER)
|
|
+ break;
|
|
+
|
|
+ next = dget(dentry);
|
|
+ /* find the topmost dentry not yet copied up */
|
|
+ for (;;) {
|
|
+ parent = dget_parent(next);
|
|
+
|
|
+ type = ovl_path_type(parent);
|
|
+ if (type != OVL_PATH_LOWER)
|
|
+ break;
|
|
+
|
|
+ dput(next);
|
|
+ next = parent;
|
|
+ }
|
|
+
|
|
+ ovl_path_lower(next, &lowerpath);
|
|
+ err = vfs_getattr(&lowerpath, &stat);
|
|
+ if (!err)
|
|
+ err = ovl_copy_up_one(parent, next, &lowerpath, &stat);
|
|
+
|
|
+ dput(parent);
|
|
+ dput(next);
|
|
+ }
|
|
+
|
|
+ return err;
|
|
+}
|
|
+
|
|
+/* Optimize by not copying up the file first and truncating later */
|
|
+int ovl_copy_up_truncate(struct dentry *dentry, loff_t size)
|
|
+{
|
|
+ int err;
|
|
+ struct kstat stat;
|
|
+ struct path lowerpath;
|
|
+ struct dentry *parent = dget_parent(dentry);
|
|
+
|
|
+ err = ovl_copy_up(parent);
|
|
+ if (err)
|
|
+ goto out_dput_parent;
|
|
+
|
|
+ ovl_path_lower(dentry, &lowerpath);
|
|
+ err = vfs_getattr(&lowerpath, &stat);
|
|
+ if (err)
|
|
+ goto out_dput_parent;
|
|
+
|
|
+ if (size < stat.size)
|
|
+ stat.size = size;
|
|
+
|
|
+ err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat);
|
|
+
|
|
+out_dput_parent:
|
|
+ dput(parent);
|
|
+ return err;
|
|
+}
|
|
--- /dev/null
|
|
+++ b/fs/overlayfs/dir.c
|
|
@@ -0,0 +1,606 @@
|
|
+/*
|
|
+ *
|
|
+ * Copyright (C) 2011 Novell Inc.
|
|
+ *
|
|
+ * This program is free software; you can redistribute it and/or modify it
|
|
+ * under the terms of the GNU General Public License version 2 as published by
|
|
+ * the Free Software Foundation.
|
|
+ */
|
|
+
|
|
+#include <linux/fs.h>
|
|
+#include <linux/namei.h>
|
|
+#include <linux/xattr.h>
|
|
+#include <linux/security.h>
|
|
+#include <linux/cred.h>
|
|
+#include "overlayfs.h"
|
|
+
|
|
+static const char *ovl_whiteout_symlink = "(overlay-whiteout)";
|
|
+
|
|
+static int ovl_whiteout(struct dentry *upperdir, struct dentry *dentry)
|
|
+{
|
|
+ int err;
|
|
+ struct dentry *newdentry;
|
|
+ const struct cred *old_cred;
|
|
+ struct cred *override_cred;
|
|
+
|
|
+ /* FIXME: recheck lower dentry to see if whiteout is really needed */
|
|
+
|
|
+ err = -ENOMEM;
|
|
+ override_cred = prepare_creds();
|
|
+ if (!override_cred)
|
|
+ goto out;
|
|
+
|
|
+ /*
|
|
+ * CAP_SYS_ADMIN for setxattr
|
|
+ * CAP_DAC_OVERRIDE for symlink creation
|
|
+ * CAP_FOWNER for unlink in sticky directory
|
|
+ */
|
|
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
|
|
+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
|
|
+ cap_raise(override_cred->cap_effective, CAP_FOWNER);
|
|
+ override_cred->fsuid = GLOBAL_ROOT_UID;
|
|
+ override_cred->fsgid = GLOBAL_ROOT_GID;
|
|
+ old_cred = override_creds(override_cred);
|
|
+
|
|
+ newdentry = lookup_one_len(dentry->d_name.name, upperdir,
|
|
+ dentry->d_name.len);
|
|
+ err = PTR_ERR(newdentry);
|
|
+ if (IS_ERR(newdentry))
|
|
+ goto out_put_cred;
|
|
+
|
|
+ /* Just been removed within the same locked region */
|
|
+ WARN_ON(newdentry->d_inode);
|
|
+
|
|
+ err = vfs_symlink(upperdir->d_inode, newdentry, ovl_whiteout_symlink);
|
|
+ if (err)
|
|
+ goto out_dput;
|
|
+
|
|
+ ovl_dentry_version_inc(dentry->d_parent);
|
|
+
|
|
+ err = vfs_setxattr(newdentry, ovl_whiteout_xattr, "y", 1, 0);
|
|
+ if (err)
|
|
+ vfs_unlink(upperdir->d_inode, newdentry, NULL);
|
|
+
|
|
+out_dput:
|
|
+ dput(newdentry);
|
|
+out_put_cred:
|
|
+ revert_creds(old_cred);
|
|
+ put_cred(override_cred);
|
|
+out:
|
|
+ if (err) {
|
|
+ /*
|
|
+ * There's no way to recover from failure to whiteout.
|
|
+ * What should we do? Log a big fat error and... ?
|
|
+ */
|
|
+ pr_err("overlayfs: ERROR - failed to whiteout '%s'\n",
|
|
+ dentry->d_name.name);
|
|
+ }
|
|
+
|
|
+ return err;
|
|
+}
|
|
+
|
|
+static struct dentry *ovl_lookup_create(struct dentry *upperdir,
|
|
+ struct dentry *template)
|
|
+{
|
|
+ int err;
|
|
+ struct dentry *newdentry;
|
|
+ struct qstr *name = &template->d_name;
|
|
+
|
|
+ newdentry = lookup_one_len(name->name, upperdir, name->len);
|
|
+ if (IS_ERR(newdentry))
|
|
+ return newdentry;
|
|
+
|
|
+ if (newdentry->d_inode) {
|
|
+ const struct cred *old_cred;
|
|
+ struct cred *override_cred;
|
|
+
|
|
+ /* No need to check whiteout if lower parent is non-existent */
|
|
+ err = -EEXIST;
|
|
+ if (!ovl_dentry_lower(template->d_parent))
|
|
+ goto out_dput;
|
|
+
|
|
+ if (!S_ISLNK(newdentry->d_inode->i_mode))
|
|
+ goto out_dput;
|
|
+
|
|
+ err = -ENOMEM;
|
|
+ override_cred = prepare_creds();
|
|
+ if (!override_cred)
|
|
+ goto out_dput;
|
|
+
|
|
+ /*
|
|
+ * CAP_SYS_ADMIN for getxattr
|
|
+ * CAP_FOWNER for unlink in sticky directory
|
|
+ */
|
|
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
|
|
+ cap_raise(override_cred->cap_effective, CAP_FOWNER);
|
|
+ old_cred = override_creds(override_cred);
|
|
+
|
|
+ err = -EEXIST;
|
|
+ if (ovl_is_whiteout(newdentry))
|
|
+ err = vfs_unlink(upperdir->d_inode, newdentry, NULL);
|
|
+
|
|
+ revert_creds(old_cred);
|
|
+ put_cred(override_cred);
|
|
+ if (err)
|
|
+ goto out_dput;
|
|
+
|
|
+ dput(newdentry);
|
|
+ newdentry = lookup_one_len(name->name, upperdir, name->len);
|
|
+ if (IS_ERR(newdentry)) {
|
|
+ ovl_whiteout(upperdir, template);
|
|
+ return newdentry;
|
|
+ }
|
|
+
|
|
+ /*
|
|
+ * Whiteout just been successfully removed, parent
|
|
+ * i_mutex is still held, there's no way the lookup
|
|
+ * could return positive.
|
|
+ */
|
|
+ WARN_ON(newdentry->d_inode);
|
|
+ }
|
|
+
|
|
+ return newdentry;
|
|
+
|
|
+out_dput:
|
|
+ dput(newdentry);
|
|
+ return ERR_PTR(err);
|
|
+}
|
|
+
|
|
+struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry,
|
|
+ struct kstat *stat, const char *link)
|
|
+{
|
|
+ int err;
|
|
+ struct dentry *newdentry;
|
|
+ struct inode *dir = upperdir->d_inode;
|
|
+
|
|
+ newdentry = ovl_lookup_create(upperdir, dentry);
|
|
+ if (IS_ERR(newdentry))
|
|
+ goto out;
|
|
+
|
|
+ switch (stat->mode & S_IFMT) {
|
|
+ case S_IFREG:
|
|
+ err = vfs_create(dir, newdentry, stat->mode, NULL);
|
|
+ break;
|
|
+
|
|
+ case S_IFDIR:
|
|
+ err = vfs_mkdir(dir, newdentry, stat->mode);
|
|
+ break;
|
|
+
|
|
+ case S_IFCHR:
|
|
+ case S_IFBLK:
|
|
+ case S_IFIFO:
|
|
+ case S_IFSOCK:
|
|
+ err = vfs_mknod(dir, newdentry, stat->mode, stat->rdev);
|
|
+ break;
|
|
+
|
|
+ case S_IFLNK:
|
|
+ err = vfs_symlink(dir, newdentry, link);
|
|
+ break;
|
|
+
|
|
+ default:
|
|
+ err = -EPERM;
|
|
+ }
|
|
+ if (err) {
|
|
+ if (ovl_dentry_is_opaque(dentry))
|
|
+ ovl_whiteout(upperdir, dentry);
|
|
+ dput(newdentry);
|
|
+ newdentry = ERR_PTR(err);
|
|
+ } else if (WARN_ON(!newdentry->d_inode)) {
|
|
+ /*
|
|
+ * Not quite sure if non-instantiated dentry is legal or not.
|
|
+ * VFS doesn't seem to care so check and warn here.
|
|
+ */
|
|
+ dput(newdentry);
|
|
+ newdentry = ERR_PTR(-ENOENT);
|
|
+ }
|
|
+
|
|
+out:
|
|
+ return newdentry;
|
|
+
|
|
+}
|
|
+
|
|
+static int ovl_set_opaque(struct dentry *upperdentry)
|
|
+{
|
|
+ int err;
|
|
+ const struct cred *old_cred;
|
|
+ struct cred *override_cred;
|
|
+
|
|
+ override_cred = prepare_creds();
|
|
+ if (!override_cred)
|
|
+ return -ENOMEM;
|
|
+
|
|
+ /* CAP_SYS_ADMIN for setxattr of "trusted" namespace */
|
|
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
|
|
+ old_cred = override_creds(override_cred);
|
|
+ err = vfs_setxattr(upperdentry, ovl_opaque_xattr, "y", 1, 0);
|
|
+ revert_creds(old_cred);
|
|
+ put_cred(override_cred);
|
|
+
|
|
+ return err;
|
|
+}
|
|
+
|
|
+static int ovl_remove_opaque(struct dentry *upperdentry)
|
|
+{
|
|
+ int err;
|
|
+ const struct cred *old_cred;
|
|
+ struct cred *override_cred;
|
|
+
|
|
+ override_cred = prepare_creds();
|
|
+ if (!override_cred)
|
|
+ return -ENOMEM;
|
|
+
|
|
+ /* CAP_SYS_ADMIN for removexattr of "trusted" namespace */
|
|
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
|
|
+ old_cred = override_creds(override_cred);
|
|
+ err = vfs_removexattr(upperdentry, ovl_opaque_xattr);
|
|
+ revert_creds(old_cred);
|
|
+ put_cred(override_cred);
|
|
+
|
|
+ return err;
|
|
+}
|
|
+
|
|
+static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
|
|
+ struct kstat *stat)
|
|
+{
|
|
+ int err;
|
|
+ enum ovl_path_type type;
|
|
+ struct path realpath;
|
|
+
|
|
+ type = ovl_path_real(dentry, &realpath);
|
|
+ err = vfs_getattr(&realpath, stat);
|
|
+ if (err)
|
|
+ return err;
|
|
+
|
|
+ stat->dev = dentry->d_sb->s_dev;
|
|
+ stat->ino = dentry->d_inode->i_ino;
|
|
+
|
|
+ /*
|
|
+ * It's probably not worth it to count subdirs to get the
|
|
+ * correct link count. nlink=1 seems to pacify 'find' and
|
|
+ * other utilities.
|
|
+ */
|
|
+ if (type == OVL_PATH_MERGE)
|
|
+ stat->nlink = 1;
|
|
+
|
|
+ return 0;
|
|
+}
|
|
+
|
|
+static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
|
|
+ const char *link)
|
|
+{
|
|
+ int err;
|
|
+ struct dentry *newdentry;
|
|
+ struct dentry *upperdir;
|
|
+ struct inode *inode;
|
|
+ struct kstat stat = {
|
|
+ .mode = mode,
|
|
+ .rdev = rdev,
|
|
+ };
|
|
+
|
|
+ err = -ENOMEM;
|
|
+ inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata);
|
|
+ if (!inode)
|
|
+ goto out;
|
|
+
|
|
+ err = ovl_copy_up(dentry->d_parent);
|
|
+ if (err)
|
|
+ goto out_iput;
|
|
+
|
|
+ upperdir = ovl_dentry_upper(dentry->d_parent);
|
|
+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
+
|
|
+ newdentry = ovl_upper_create(upperdir, dentry, &stat, link);
|
|
+ err = PTR_ERR(newdentry);
|
|
+ if (IS_ERR(newdentry))
|
|
+ goto out_unlock;
|
|
+
|
|
+ ovl_dentry_version_inc(dentry->d_parent);
|
|
+ if (ovl_dentry_is_opaque(dentry) && S_ISDIR(mode)) {
|
|
+ err = ovl_set_opaque(newdentry);
|
|
+ if (err) {
|
|
+ vfs_rmdir(upperdir->d_inode, newdentry);
|
|
+ ovl_whiteout(upperdir, dentry);
|
|
+ goto out_dput;
|
|
+ }
|
|
+ }
|
|
+ ovl_dentry_update(dentry, newdentry);
|
|
+ ovl_copyattr(newdentry->d_inode, inode);
|
|
+ d_instantiate(dentry, inode);
|
|
+ inode = NULL;
|
|
+ newdentry = NULL;
|
|
+ err = 0;
|
|
+
|
|
+out_dput:
|
|
+ dput(newdentry);
|
|
+out_unlock:
|
|
+ mutex_unlock(&upperdir->d_inode->i_mutex);
|
|
+out_iput:
|
|
+ iput(inode);
|
|
+out:
|
|
+ return err;
|
|
+}
|
|
+
|
|
+static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
|
|
+ bool excl)
|
|
+{
|
|
+ return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
|
|
+}
|
|
+
|
|
+static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
|
|
+{
|
|
+ return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
|
|
+}
|
|
+
|
|
+static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
|
|
+ dev_t rdev)
|
|
+{
|
|
+ return ovl_create_object(dentry, mode, rdev, NULL);
|
|
+}
|
|
+
|
|
+static int ovl_symlink(struct inode *dir, struct dentry *dentry,
|
|
+ const char *link)
|
|
+{
|
|
+ return ovl_create_object(dentry, S_IFLNK, 0, link);
|
|
+}
|
|
+
|
|
+static int ovl_do_remove(struct dentry *dentry, bool is_dir)
|
|
+{
|
|
+ int err;
|
|
+ enum ovl_path_type type;
|
|
+ struct path realpath;
|
|
+ struct dentry *upperdir;
|
|
+
|
|
+ err = ovl_copy_up(dentry->d_parent);
|
|
+ if (err)
|
|
+ return err;
|
|
+
|
|
+ upperdir = ovl_dentry_upper(dentry->d_parent);
|
|
+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
+ type = ovl_path_real(dentry, &realpath);
|
|
+ if (type != OVL_PATH_LOWER) {
|
|
+ err = -ESTALE;
|
|
+ if (realpath.dentry->d_parent != upperdir)
|
|
+ goto out_d_drop;
|
|
+
|
|
+ /* FIXME: create whiteout up front and rename to target */
|
|
+
|
|
+ if (is_dir)
|
|
+ err = vfs_rmdir(upperdir->d_inode, realpath.dentry);
|
|
+ else
|
|
+ err = vfs_unlink(upperdir->d_inode, realpath.dentry,
|
|
+ NULL);
|
|
+ if (err)
|
|
+ goto out_d_drop;
|
|
+
|
|
+ ovl_dentry_version_inc(dentry->d_parent);
|
|
+ }
|
|
+
|
|
+ if (type != OVL_PATH_UPPER || ovl_dentry_is_opaque(dentry))
|
|
+ err = ovl_whiteout(upperdir, dentry);
|
|
+
|
|
+ /*
|
|
+ * Keeping this dentry hashed would mean having to release
|
|
+ * upperpath/lowerpath, which could only be done if we are the
|
|
+ * sole user of this dentry. Too tricky... Just unhash for
|
|
+ * now.
|
|
+ */
|
|
+out_d_drop:
|
|
+ d_drop(dentry);
|
|
+ mutex_unlock(&upperdir->d_inode->i_mutex);
|
|
+
|
|
+ return err;
|
|
+}
|
|
+
|
|
+static int ovl_unlink(struct inode *dir, struct dentry *dentry)
|
|
+{
|
|
+ return ovl_do_remove(dentry, false);
|
|
+}
|
|
+
|
|
+
|
|
+static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
|
|
+{
|
|
+ int err;
|
|
+ enum ovl_path_type type;
|
|
+
|
|
+ type = ovl_path_type(dentry);
|
|
+ if (type != OVL_PATH_UPPER) {
|
|
+ err = ovl_check_empty_and_clear(dentry, type);
|
|
+ if (err)
|
|
+ return err;
|
|
+ }
|
|
+
|
|
+ return ovl_do_remove(dentry, true);
|
|
+}
|
|
+
|
|
+static int ovl_link(struct dentry *old, struct inode *newdir,
|
|
+ struct dentry *new)
|
|
+{
|
|
+ int err;
|
|
+ struct dentry *olddentry;
|
|
+ struct dentry *newdentry;
|
|
+ struct dentry *upperdir;
|
|
+ struct inode *newinode;
|
|
+
|
|
+ err = ovl_copy_up(old);
|
|
+ if (err)
|
|
+ goto out;
|
|
+
|
|
+ err = ovl_copy_up(new->d_parent);
|
|
+ if (err)
|
|
+ goto out;
|
|
+
|
|
+ upperdir = ovl_dentry_upper(new->d_parent);
|
|
+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
+ newdentry = ovl_lookup_create(upperdir, new);
|
|
+ err = PTR_ERR(newdentry);
|
|
+ if (IS_ERR(newdentry))
|
|
+ goto out_unlock;
|
|
+
|
|
+ olddentry = ovl_dentry_upper(old);
|
|
+ err = vfs_link(olddentry, upperdir->d_inode, newdentry, NULL);
|
|
+ if (!err) {
|
|
+ if (WARN_ON(!newdentry->d_inode)) {
|
|
+ dput(newdentry);
|
|
+ err = -ENOENT;
|
|
+ goto out_unlock;
|
|
+ }
|
|
+ newinode = ovl_new_inode(old->d_sb, newdentry->d_inode->i_mode,
|
|
+ new->d_fsdata);
|
|
+ if (!newinode) {
|
|
+ err = -ENOMEM;
|
|
+ goto link_fail;
|
|
+ }
|
|
+ ovl_copyattr(upperdir->d_inode, newinode);
|
|
+
|
|
+ ovl_dentry_version_inc(new->d_parent);
|
|
+ ovl_dentry_update(new, newdentry);
|
|
+
|
|
+ d_instantiate(new, newinode);
|
|
+ } else {
|
|
+link_fail:
|
|
+ if (ovl_dentry_is_opaque(new))
|
|
+ ovl_whiteout(upperdir, new);
|
|
+ dput(newdentry);
|
|
+ }
|
|
+out_unlock:
|
|
+ mutex_unlock(&upperdir->d_inode->i_mutex);
|
|
+out:
|
|
+ return err;
|
|
+}
|
|
+
|
|
+static int ovl_rename(struct inode *olddir, struct dentry *old,
|
|
+ struct inode *newdir, struct dentry *new)
|
|
+{
|
|
+ int err;
|
|
+ enum ovl_path_type old_type;
|
|
+ enum ovl_path_type new_type;
|
|
+ struct dentry *old_upperdir;
|
|
+ struct dentry *new_upperdir;
|
|
+ struct dentry *olddentry;
|
|
+ struct dentry *newdentry;
|
|
+ struct dentry *trap;
|
|
+ bool old_opaque;
|
|
+ bool new_opaque;
|
|
+ bool new_create = false;
|
|
+ bool is_dir = S_ISDIR(old->d_inode->i_mode);
|
|
+
|
|
+ /* Don't copy up directory trees */
|
|
+ old_type = ovl_path_type(old);
|
|
+ if (old_type != OVL_PATH_UPPER && is_dir)
|
|
+ return -EXDEV;
|
|
+
|
|
+ if (new->d_inode) {
|
|
+ new_type = ovl_path_type(new);
|
|
+
|
|
+ if (new_type == OVL_PATH_LOWER && old_type == OVL_PATH_LOWER) {
|
|
+ if (ovl_dentry_lower(old)->d_inode ==
|
|
+ ovl_dentry_lower(new)->d_inode)
|
|
+ return 0;
|
|
+ }
|
|
+ if (new_type != OVL_PATH_LOWER && old_type != OVL_PATH_LOWER) {
|
|
+ if (ovl_dentry_upper(old)->d_inode ==
|
|
+ ovl_dentry_upper(new)->d_inode)
|
|
+ return 0;
|
|
+ }
|
|
+
|
|
+ if (new_type != OVL_PATH_UPPER &&
|
|
+ S_ISDIR(new->d_inode->i_mode)) {
|
|
+ err = ovl_check_empty_and_clear(new, new_type);
|
|
+ if (err)
|
|
+ return err;
|
|
+ }
|
|
+ } else {
|
|
+ new_type = OVL_PATH_UPPER;
|
|
+ }
|
|
+
|
|
+ err = ovl_copy_up(old);
|
|
+ if (err)
|
|
+ return err;
|
|
+
|
|
+ err = ovl_copy_up(new->d_parent);
|
|
+ if (err)
|
|
+ return err;
|
|
+
|
|
+ old_upperdir = ovl_dentry_upper(old->d_parent);
|
|
+ new_upperdir = ovl_dentry_upper(new->d_parent);
|
|
+
|
|
+ trap = lock_rename(new_upperdir, old_upperdir);
|
|
+
|
|
+ olddentry = ovl_dentry_upper(old);
|
|
+ newdentry = ovl_dentry_upper(new);
|
|
+ if (newdentry) {
|
|
+ dget(newdentry);
|
|
+ } else {
|
|
+ new_create = true;
|
|
+ newdentry = ovl_lookup_create(new_upperdir, new);
|
|
+ err = PTR_ERR(newdentry);
|
|
+ if (IS_ERR(newdentry))
|
|
+ goto out_unlock;
|
|
+ }
|
|
+
|
|
+ err = -ESTALE;
|
|
+ if (olddentry->d_parent != old_upperdir)
|
|
+ goto out_dput;
|
|
+ if (newdentry->d_parent != new_upperdir)
|
|
+ goto out_dput;
|
|
+ if (olddentry == trap)
|
|
+ goto out_dput;
|
|
+ if (newdentry == trap)
|
|
+ goto out_dput;
|
|
+
|
|
+ old_opaque = ovl_dentry_is_opaque(old);
|
|
+ new_opaque = ovl_dentry_is_opaque(new) || new_type != OVL_PATH_UPPER;
|
|
+
|
|
+ if (is_dir && !old_opaque && new_opaque) {
|
|
+ err = ovl_set_opaque(olddentry);
|
|
+ if (err)
|
|
+ goto out_dput;
|
|
+ }
|
|
+
|
|
+ err = vfs_rename(old_upperdir->d_inode, olddentry,
|
|
+ new_upperdir->d_inode, newdentry, NULL);
|
|
+
|
|
+ if (err) {
|
|
+ if (new_create && ovl_dentry_is_opaque(new))
|
|
+ ovl_whiteout(new_upperdir, new);
|
|
+ if (is_dir && !old_opaque && new_opaque)
|
|
+ ovl_remove_opaque(olddentry);
|
|
+ goto out_dput;
|
|
+ }
|
|
+
|
|
+ if (old_type != OVL_PATH_UPPER || old_opaque)
|
|
+ err = ovl_whiteout(old_upperdir, old);
|
|
+ if (is_dir && old_opaque && !new_opaque)
|
|
+ ovl_remove_opaque(olddentry);
|
|
+
|
|
+ if (old_opaque != new_opaque)
|
|
+ ovl_dentry_set_opaque(old, new_opaque);
|
|
+
|
|
+ ovl_dentry_version_inc(old->d_parent);
|
|
+ ovl_dentry_version_inc(new->d_parent);
|
|
+
|
|
+out_dput:
|
|
+ dput(newdentry);
|
|
+out_unlock:
|
|
+ unlock_rename(new_upperdir, old_upperdir);
|
|
+ return err;
|
|
+}
|
|
+
|
|
+const struct inode_operations ovl_dir_inode_operations = {
|
|
+ .lookup = ovl_lookup,
|
|
+ .mkdir = ovl_mkdir,
|
|
+ .symlink = ovl_symlink,
|
|
+ .unlink = ovl_unlink,
|
|
+ .rmdir = ovl_rmdir,
|
|
+ .rename = ovl_rename,
|
|
+ .link = ovl_link,
|
|
+ .setattr = ovl_setattr,
|
|
+ .create = ovl_create,
|
|
+ .mknod = ovl_mknod,
|
|
+ .permission = ovl_permission,
|
|
+ .getattr = ovl_dir_getattr,
|
|
+ .setxattr = ovl_setxattr,
|
|
+ .getxattr = ovl_getxattr,
|
|
+ .listxattr = ovl_listxattr,
|
|
+ .removexattr = ovl_removexattr,
|
|
+};
|
|
--- /dev/null
|
|
+++ b/fs/overlayfs/inode.c
|
|
@@ -0,0 +1,372 @@
|
|
+/*
|
|
+ *
|
|
+ * Copyright (C) 2011 Novell Inc.
|
|
+ *
|
|
+ * This program is free software; you can redistribute it and/or modify it
|
|
+ * under the terms of the GNU General Public License version 2 as published by
|
|
+ * the Free Software Foundation.
|
|
+ */
|
|
+
|
|
+#include <linux/fs.h>
|
|
+#include <linux/slab.h>
|
|
+#include <linux/xattr.h>
|
|
+#include "overlayfs.h"
|
|
+
|
|
+int ovl_setattr(struct dentry *dentry, struct iattr *attr)
|
|
+{
|
|
+ struct dentry *upperdentry;
|
|
+ int err;
|
|
+
|
|
+ if ((attr->ia_valid & ATTR_SIZE) && !ovl_dentry_upper(dentry))
|
|
+ err = ovl_copy_up_truncate(dentry, attr->ia_size);
|
|
+ else
|
|
+ err = ovl_copy_up(dentry);
|
|
+ if (err)
|
|
+ return err;
|
|
+
|
|
+ upperdentry = ovl_dentry_upper(dentry);
|
|
+
|
|
+ if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
|
|
+ attr->ia_valid &= ~ATTR_MODE;
|
|
+
|
|
+ mutex_lock(&upperdentry->d_inode->i_mutex);
|
|
+ err = notify_change(upperdentry, attr, NULL);
|
|
+ if (!err)
|
|
+ ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
|
|
+ mutex_unlock(&upperdentry->d_inode->i_mutex);
|
|
+
|
|
+ return err;
|
|
+}
|
|
+
|
|
+static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry,
|
|
+ struct kstat *stat)
|
|
+{
|
|
+ struct path realpath;
|
|
+
|
|
+ ovl_path_real(dentry, &realpath);
|
|
+ return vfs_getattr(&realpath, stat);
|
|
+}
|
|
+
|
|
+int ovl_permission(struct inode *inode, int mask)
|
|
+{
|
|
+ struct ovl_entry *oe;
|
|
+ struct dentry *alias = NULL;
|
|
+ struct inode *realinode;
|
|
+ struct dentry *realdentry;
|
|
+ bool is_upper;
|
|
+ int err;
|
|
+
|
|
+ if (S_ISDIR(inode->i_mode)) {
|
|
+ oe = inode->i_private;
|
|
+ } else if (mask & MAY_NOT_BLOCK) {
|
|
+ return -ECHILD;
|
|
+ } else {
|
|
+ /*
|
|
+ * For non-directories find an alias and get the info
|
|
+ * from there.
|
|
+ */
|
|
+ alias = d_find_any_alias(inode);
|
|
+ if (WARN_ON(!alias))
|
|
+ return -ENOENT;
|
|
+
|
|
+ oe = alias->d_fsdata;
|
|
+ }
|
|
+
|
|
+ realdentry = ovl_entry_real(oe, &is_upper);
|
|
+
|
|
+ /* Careful in RCU walk mode */
|
|
+ realinode = ACCESS_ONCE(realdentry->d_inode);
|
|
+ if (!realinode) {
|
|
+ WARN_ON(!(mask & MAY_NOT_BLOCK));
|
|
+ err = -ENOENT;
|
|
+ goto out_dput;
|
|
+ }
|
|
+
|
|
+ if (mask & MAY_WRITE) {
|
|
+ umode_t mode = realinode->i_mode;
|
|
+
|
|
+ /*
|
|
+ * Writes will always be redirected to upper layer, so
|
|
+ * ignore lower layer being read-only.
|
|
+ *
|
|
+ * If the overlay itself is read-only then proceed
|
|
+ * with the permission check, don't return EROFS.
|
|
+ * This will only happen if this is the lower layer of
|
|
+ * another overlayfs.
|
|
+ *
|
|
+ * If upper fs becomes read-only after the overlay was
|
|
+ * constructed return EROFS to prevent modification of
|
|
+ * upper layer.
|
|
+ */
|
|
+ err = -EROFS;
|
|
+ if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) &&
|
|
+ (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
|
|
+ goto out_dput;
|
|
+ }
|
|
+
|
|
+ err = __inode_permission(realinode, mask);
|
|
+out_dput:
|
|
+ dput(alias);
|
|
+ return err;
|
|
+}
|
|
+
|
|
+
|
|
+struct ovl_link_data {
|
|
+ struct dentry *realdentry;
|
|
+ void *cookie;
|
|
+};
|
|
+
|
|
+static void *ovl_follow_link(struct dentry *dentry, struct nameidata *nd)
|
|
+{
|
|
+ void *ret;
|
|
+ struct dentry *realdentry;
|
|
+ struct inode *realinode;
|
|
+
|
|
+ realdentry = ovl_dentry_real(dentry);
|
|
+ realinode = realdentry->d_inode;
|
|
+
|
|
+ if (WARN_ON(!realinode->i_op->follow_link))
|
|
+ return ERR_PTR(-EPERM);
|
|
+
|
|
+ ret = realinode->i_op->follow_link(realdentry, nd);
|
|
+ if (IS_ERR(ret))
|
|
+ return ret;
|
|
+
|
|
+ if (realinode->i_op->put_link) {
|
|
+ struct ovl_link_data *data;
|
|
+
|
|
+ data = kmalloc(sizeof(struct ovl_link_data), GFP_KERNEL);
|
|
+ if (!data) {
|
|
+ realinode->i_op->put_link(realdentry, nd, ret);
|
|
+ return ERR_PTR(-ENOMEM);
|
|
+ }
|
|
+ data->realdentry = realdentry;
|
|
+ data->cookie = ret;
|
|
+
|
|
+ return data;
|
|
+ } else {
|
|
+ return NULL;
|
|
+ }
|
|
+}
|
|
+
|
|
+static void ovl_put_link(struct dentry *dentry, struct nameidata *nd, void *c)
|
|
+{
|
|
+ struct inode *realinode;
|
|
+ struct ovl_link_data *data = c;
|
|
+
|
|
+ if (!data)
|
|
+ return;
|
|
+
|
|
+ realinode = data->realdentry->d_inode;
|
|
+ realinode->i_op->put_link(data->realdentry, nd, data->cookie);
|
|
+ kfree(data);
|
|
+}
|
|
+
|
|
+static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
|
|
+{
|
|
+ struct path realpath;
|
|
+ struct inode *realinode;
|
|
+
|
|
+ ovl_path_real(dentry, &realpath);
|
|
+ realinode = realpath.dentry->d_inode;
|
|
+
|
|
+ if (!realinode->i_op->readlink)
|
|
+ return -EINVAL;
|
|
+
|
|
+ touch_atime(&realpath);
|
|
+
|
|
+ return realinode->i_op->readlink(realpath.dentry, buf, bufsiz);
|
|
+}
|
|
+
|
|
+
|
|
+static bool ovl_is_private_xattr(const char *name)
|
|
+{
|
|
+ return strncmp(name, "trusted.overlay.", 14) == 0;
|
|
+}
|
|
+
|
|
+int ovl_setxattr(struct dentry *dentry, const char *name,
|
|
+ const void *value, size_t size, int flags)
|
|
+{
|
|
+ int err;
|
|
+ struct dentry *upperdentry;
|
|
+
|
|
+ if (ovl_is_private_xattr(name))
|
|
+ return -EPERM;
|
|
+
|
|
+ err = ovl_copy_up(dentry);
|
|
+ if (err)
|
|
+ return err;
|
|
+
|
|
+ upperdentry = ovl_dentry_upper(dentry);
|
|
+ return vfs_setxattr(upperdentry, name, value, size, flags);
|
|
+}
|
|
+
|
|
+ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
|
|
+ void *value, size_t size)
|
|
+{
|
|
+ if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE &&
|
|
+ ovl_is_private_xattr(name))
|
|
+ return -ENODATA;
|
|
+
|
|
+ return vfs_getxattr(ovl_dentry_real(dentry), name, value, size);
|
|
+}
|
|
+
|
|
+ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
|
|
+{
|
|
+ ssize_t res;
|
|
+ int off;
|
|
+
|
|
+ res = vfs_listxattr(ovl_dentry_real(dentry), list, size);
|
|
+ if (res <= 0 || size == 0)
|
|
+ return res;
|
|
+
|
|
+ if (ovl_path_type(dentry->d_parent) != OVL_PATH_MERGE)
|
|
+ return res;
|
|
+
|
|
+ /* filter out private xattrs */
|
|
+ for (off = 0; off < res;) {
|
|
+ char *s = list + off;
|
|
+ size_t slen = strlen(s) + 1;
|
|
+
|
|
+ BUG_ON(off + slen > res);
|
|
+
|
|
+ if (ovl_is_private_xattr(s)) {
|
|
+ res -= slen;
|
|
+ memmove(s, s + slen, res - off);
|
|
+ } else {
|
|
+ off += slen;
|
|
+ }
|
|
+ }
|
|
+
|
|
+ return res;
|
|
+}
|
|
+
|
|
+int ovl_removexattr(struct dentry *dentry, const char *name)
|
|
+{
|
|
+ int err;
|
|
+ struct path realpath;
|
|
+ enum ovl_path_type type;
|
|
+
|
|
+ if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE &&
|
|
+ ovl_is_private_xattr(name))
|
|
+ return -ENODATA;
|
|
+
|
|
+ type = ovl_path_real(dentry, &realpath);
|
|
+ if (type == OVL_PATH_LOWER) {
|
|
+ err = vfs_getxattr(realpath.dentry, name, NULL, 0);
|
|
+ if (err < 0)
|
|
+ return err;
|
|
+
|
|
+ err = ovl_copy_up(dentry);
|
|
+ if (err)
|
|
+ return err;
|
|
+
|
|
+ ovl_path_upper(dentry, &realpath);
|
|
+ }
|
|
+
|
|
+ return vfs_removexattr(realpath.dentry, name);
|
|
+}
|
|
+
|
|
+static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
|
|
+ struct dentry *realdentry)
|
|
+{
|
|
+ if (type != OVL_PATH_LOWER)
|
|
+ return false;
|
|
+
|
|
+ if (special_file(realdentry->d_inode->i_mode))
|
|
+ return false;
|
|
+
|
|
+ if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC))
|
|
+ return false;
|
|
+
|
|
+ return true;
|
|
+}
|
|
+
|
|
+static int ovl_dentry_open(struct dentry *dentry, struct file *file,
|
|
+ const struct cred *cred)
|
|
+{
|
|
+ int err;
|
|
+ struct path realpath;
|
|
+ enum ovl_path_type type;
|
|
+
|
|
+ type = ovl_path_real(dentry, &realpath);
|
|
+ if (ovl_open_need_copy_up(file->f_flags, type, realpath.dentry)) {
|
|
+ if (file->f_flags & O_TRUNC)
|
|
+ err = ovl_copy_up_truncate(dentry, 0);
|
|
+ else
|
|
+ err = ovl_copy_up(dentry);
|
|
+ if (err)
|
|
+ return err;
|
|
+
|
|
+ ovl_path_upper(dentry, &realpath);
|
|
+ }
|
|
+
|
|
+ return vfs_open(&realpath, file, cred);
|
|
+}
|
|
+
|
|
+static const struct inode_operations ovl_file_inode_operations = {
|
|
+ .setattr = ovl_setattr,
|
|
+ .permission = ovl_permission,
|
|
+ .getattr = ovl_getattr,
|
|
+ .setxattr = ovl_setxattr,
|
|
+ .getxattr = ovl_getxattr,
|
|
+ .listxattr = ovl_listxattr,
|
|
+ .removexattr = ovl_removexattr,
|
|
+ .dentry_open = ovl_dentry_open,
|
|
+};
|
|
+
|
|
+static const struct inode_operations ovl_symlink_inode_operations = {
|
|
+ .setattr = ovl_setattr,
|
|
+ .follow_link = ovl_follow_link,
|
|
+ .put_link = ovl_put_link,
|
|
+ .readlink = ovl_readlink,
|
|
+ .getattr = ovl_getattr,
|
|
+ .setxattr = ovl_setxattr,
|
|
+ .getxattr = ovl_getxattr,
|
|
+ .listxattr = ovl_listxattr,
|
|
+ .removexattr = ovl_removexattr,
|
|
+};
|
|
+
|
|
+struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
|
|
+ struct ovl_entry *oe)
|
|
+{
|
|
+ struct inode *inode;
|
|
+
|
|
+ inode = new_inode(sb);
|
|
+ if (!inode)
|
|
+ return NULL;
|
|
+
|
|
+ mode &= S_IFMT;
|
|
+
|
|
+ inode->i_ino = get_next_ino();
|
|
+ inode->i_mode = mode;
|
|
+ inode->i_flags |= S_NOATIME | S_NOCMTIME;
|
|
+
|
|
+ switch (mode) {
|
|
+ case S_IFDIR:
|
|
+ inode->i_private = oe;
|
|
+ inode->i_op = &ovl_dir_inode_operations;
|
|
+ inode->i_fop = &ovl_dir_operations;
|
|
+ break;
|
|
+
|
|
+ case S_IFLNK:
|
|
+ inode->i_op = &ovl_symlink_inode_operations;
|
|
+ break;
|
|
+
|
|
+ case S_IFREG:
|
|
+ case S_IFSOCK:
|
|
+ case S_IFBLK:
|
|
+ case S_IFCHR:
|
|
+ case S_IFIFO:
|
|
+ inode->i_op = &ovl_file_inode_operations;
|
|
+ break;
|
|
+
|
|
+ default:
|
|
+ WARN(1, "illegal file type: %i\n", mode);
|
|
+ iput(inode);
|
|
+ inode = NULL;
|
|
+ }
|
|
+
|
|
+ return inode;
|
|
+
|
|
+}
|
|
--- /dev/null
|
|
+++ b/fs/overlayfs/overlayfs.h
|
|
@@ -0,0 +1,70 @@
|
|
+/*
|
|
+ *
|
|
+ * Copyright (C) 2011 Novell Inc.
|
|
+ *
|
|
+ * This program is free software; you can redistribute it and/or modify it
|
|
+ * under the terms of the GNU General Public License version 2 as published by
|
|
+ * the Free Software Foundation.
|
|
+ */
|
|
+
|
|
+struct ovl_entry;
|
|
+
|
|
+enum ovl_path_type {
|
|
+ OVL_PATH_UPPER,
|
|
+ OVL_PATH_MERGE,
|
|
+ OVL_PATH_LOWER,
|
|
+};
|
|
+
|
|
+extern const char *ovl_opaque_xattr;
|
|
+extern const char *ovl_whiteout_xattr;
|
|
+extern const struct dentry_operations ovl_dentry_operations;
|
|
+
|
|
+enum ovl_path_type ovl_path_type(struct dentry *dentry);
|
|
+u64 ovl_dentry_version_get(struct dentry *dentry);
|
|
+void ovl_dentry_version_inc(struct dentry *dentry);
|
|
+void ovl_path_upper(struct dentry *dentry, struct path *path);
|
|
+void ovl_path_lower(struct dentry *dentry, struct path *path);
|
|
+enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
|
|
+struct dentry *ovl_dentry_upper(struct dentry *dentry);
|
|
+struct dentry *ovl_dentry_lower(struct dentry *dentry);
|
|
+struct dentry *ovl_dentry_real(struct dentry *dentry);
|
|
+struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper);
|
|
+bool ovl_dentry_is_opaque(struct dentry *dentry);
|
|
+void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque);
|
|
+bool ovl_is_whiteout(struct dentry *dentry);
|
|
+void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry);
|
|
+struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
|
|
+ unsigned int flags);
|
|
+struct file *ovl_path_open(struct path *path, int flags);
|
|
+
|
|
+struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry,
|
|
+ struct kstat *stat, const char *link);
|
|
+
|
|
+/* readdir.c */
|
|
+extern const struct file_operations ovl_dir_operations;
|
|
+int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type);
|
|
+
|
|
+/* inode.c */
|
|
+int ovl_setattr(struct dentry *dentry, struct iattr *attr);
|
|
+int ovl_permission(struct inode *inode, int mask);
|
|
+int ovl_setxattr(struct dentry *dentry, const char *name,
|
|
+ const void *value, size_t size, int flags);
|
|
+ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
|
|
+ void *value, size_t size);
|
|
+ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
|
|
+int ovl_removexattr(struct dentry *dentry, const char *name);
|
|
+
|
|
+struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
|
|
+ struct ovl_entry *oe);
|
|
+static inline void ovl_copyattr(struct inode *from, struct inode *to)
|
|
+{
|
|
+ to->i_uid = from->i_uid;
|
|
+ to->i_gid = from->i_gid;
|
|
+}
|
|
+
|
|
+/* dir.c */
|
|
+extern const struct inode_operations ovl_dir_inode_operations;
|
|
+
|
|
+/* copy_up.c */
|
|
+int ovl_copy_up(struct dentry *dentry);
|
|
+int ovl_copy_up_truncate(struct dentry *dentry, loff_t size);
|
|
--- /dev/null
|
|
+++ b/fs/overlayfs/readdir.c
|
|
@@ -0,0 +1,567 @@
|
|
+/*
|
|
+ *
|
|
+ * Copyright (C) 2011 Novell Inc.
|
|
+ *
|
|
+ * This program is free software; you can redistribute it and/or modify it
|
|
+ * under the terms of the GNU General Public License version 2 as published by
|
|
+ * the Free Software Foundation.
|
|
+ */
|
|
+
|
|
+#include <linux/fs.h>
|
|
+#include <linux/slab.h>
|
|
+#include <linux/namei.h>
|
|
+#include <linux/file.h>
|
|
+#include <linux/xattr.h>
|
|
+#include <linux/rbtree.h>
|
|
+#include <linux/security.h>
|
|
+#include <linux/cred.h>
|
|
+#include "overlayfs.h"
|
|
+
|
|
+struct ovl_cache_entry {
|
|
+ const char *name;
|
|
+ unsigned int len;
|
|
+ unsigned int type;
|
|
+ u64 ino;
|
|
+ bool is_whiteout;
|
|
+ struct list_head l_node;
|
|
+ struct rb_node node;
|
|
+};
|
|
+
|
|
+struct ovl_readdir_data {
|
|
+ struct dir_context ctx;
|
|
+ bool is_merge;
|
|
+ struct rb_root *root;
|
|
+ struct list_head *list;
|
|
+ struct list_head *middle;
|
|
+ struct dentry *dir;
|
|
+ int count;
|
|
+ int err;
|
|
+};
|
|
+
|
|
+struct ovl_dir_file {
|
|
+ bool is_real;
|
|
+ bool is_cached;
|
|
+ struct list_head cursor;
|
|
+ u64 cache_version;
|
|
+ struct list_head cache;
|
|
+ struct file *realfile;
|
|
+};
|
|
+
|
|
+static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n)
|
|
+{
|
|
+ return container_of(n, struct ovl_cache_entry, node);
|
|
+}
|
|
+
|
|
+static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
|
|
+ const char *name, int len)
|
|
+{
|
|
+ struct rb_node *node = root->rb_node;
|
|
+ int cmp;
|
|
+
|
|
+ while (node) {
|
|
+ struct ovl_cache_entry *p = ovl_cache_entry_from_node(node);
|
|
+
|
|
+ cmp = strncmp(name, p->name, len);
|
|
+ if (cmp > 0)
|
|
+ node = p->node.rb_right;
|
|
+ else if (cmp < 0 || len < p->len)
|
|
+ node = p->node.rb_left;
|
|
+ else
|
|
+ return p;
|
|
+ }
|
|
+
|
|
+ return NULL;
|
|
+}
|
|
+
|
|
+static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len,
|
|
+ u64 ino, unsigned int d_type)
|
|
+{
|
|
+ struct ovl_cache_entry *p;
|
|
+
|
|
+ p = kmalloc(sizeof(*p) + len + 1, GFP_KERNEL);
|
|
+ if (p) {
|
|
+ char *name_copy = (char *) (p + 1);
|
|
+ memcpy(name_copy, name, len);
|
|
+ name_copy[len] = '\0';
|
|
+ p->name = name_copy;
|
|
+ p->len = len;
|
|
+ p->type = d_type;
|
|
+ p->ino = ino;
|
|
+ p->is_whiteout = false;
|
|
+ }
|
|
+
|
|
+ return p;
|
|
+}
|
|
+
|
|
+static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
|
|
+ const char *name, int len, u64 ino,
|
|
+ unsigned int d_type)
|
|
+{
|
|
+ struct rb_node **newp = &rdd->root->rb_node;
|
|
+ struct rb_node *parent = NULL;
|
|
+ struct ovl_cache_entry *p;
|
|
+
|
|
+ while (*newp) {
|
|
+ int cmp;
|
|
+ struct ovl_cache_entry *tmp;
|
|
+
|
|
+ parent = *newp;
|
|
+ tmp = ovl_cache_entry_from_node(*newp);
|
|
+ cmp = strncmp(name, tmp->name, len);
|
|
+ if (cmp > 0)
|
|
+ newp = &tmp->node.rb_right;
|
|
+ else if (cmp < 0 || len < tmp->len)
|
|
+ newp = &tmp->node.rb_left;
|
|
+ else
|
|
+ return 0;
|
|
+ }
|
|
+
|
|
+ p = ovl_cache_entry_new(name, len, ino, d_type);
|
|
+ if (p == NULL)
|
|
+ return -ENOMEM;
|
|
+
|
|
+ list_add_tail(&p->l_node, rdd->list);
|
|
+ rb_link_node(&p->node, parent, newp);
|
|
+ rb_insert_color(&p->node, rdd->root);
|
|
+
|
|
+ return 0;
|
|
+}
|
|
+
|
|
+static int ovl_fill_lower(struct ovl_readdir_data *rdd,
|
|
+ const char *name, int namelen,
|
|
+ loff_t offset, u64 ino, unsigned int d_type)
|
|
+{
|
|
+ struct ovl_cache_entry *p;
|
|
+
|
|
+ p = ovl_cache_entry_find(rdd->root, name, namelen);
|
|
+ if (p) {
|
|
+ list_move_tail(&p->l_node, rdd->middle);
|
|
+ } else {
|
|
+ p = ovl_cache_entry_new(name, namelen, ino, d_type);
|
|
+ if (p == NULL)
|
|
+ rdd->err = -ENOMEM;
|
|
+ else
|
|
+ list_add_tail(&p->l_node, rdd->middle);
|
|
+ }
|
|
+
|
|
+ return rdd->err;
|
|
+}
|
|
+
|
|
+static void ovl_cache_free(struct list_head *list)
|
|
+{
|
|
+ struct ovl_cache_entry *p;
|
|
+ struct ovl_cache_entry *n;
|
|
+
|
|
+ list_for_each_entry_safe(p, n, list, l_node)
|
|
+ kfree(p);
|
|
+
|
|
+ INIT_LIST_HEAD(list);
|
|
+}
|
|
+
|
|
+static int ovl_fill_merge(void *buf, const char *name, int namelen,
|
|
+ loff_t offset, u64 ino, unsigned int d_type)
|
|
+{
|
|
+ struct ovl_readdir_data *rdd = buf;
|
|
+
|
|
+ rdd->count++;
|
|
+ if (!rdd->is_merge)
|
|
+ return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
|
|
+ else
|
|
+ return ovl_fill_lower(rdd, name, namelen, offset, ino, d_type);
|
|
+}
|
|
+
|
|
+static inline int ovl_dir_read(struct path *realpath,
|
|
+ struct ovl_readdir_data *rdd)
|
|
+{
|
|
+ struct file *realfile;
|
|
+ int err;
|
|
+
|
|
+ realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY);
|
|
+ if (IS_ERR(realfile))
|
|
+ return PTR_ERR(realfile);
|
|
+
|
|
+ rdd->ctx.pos = 0;
|
|
+ do {
|
|
+ rdd->count = 0;
|
|
+ rdd->err = 0;
|
|
+ err = iterate_dir(realfile, &rdd->ctx);
|
|
+ if (err >= 0)
|
|
+ err = rdd->err;
|
|
+ } while (!err && rdd->count);
|
|
+ fput(realfile);
|
|
+
|
|
+ return 0;
|
|
+}
|
|
+
|
|
+static void ovl_dir_reset(struct file *file)
|
|
+{
|
|
+ struct ovl_dir_file *od = file->private_data;
|
|
+ enum ovl_path_type type = ovl_path_type(file->f_path.dentry);
|
|
+
|
|
+ if (ovl_dentry_version_get(file->f_path.dentry) != od->cache_version) {
|
|
+ list_del_init(&od->cursor);
|
|
+ ovl_cache_free(&od->cache);
|
|
+ od->is_cached = false;
|
|
+ }
|
|
+ WARN_ON(!od->is_real && type != OVL_PATH_MERGE);
|
|
+ if (od->is_real && type == OVL_PATH_MERGE) {
|
|
+ fput(od->realfile);
|
|
+ od->realfile = NULL;
|
|
+ od->is_real = false;
|
|
+ }
|
|
+}
|
|
+
|
|
+static int ovl_dir_mark_whiteouts(struct ovl_readdir_data *rdd)
|
|
+{
|
|
+ struct ovl_cache_entry *p;
|
|
+ struct dentry *dentry;
|
|
+ const struct cred *old_cred;
|
|
+ struct cred *override_cred;
|
|
+
|
|
+ override_cred = prepare_creds();
|
|
+ if (!override_cred) {
|
|
+ ovl_cache_free(rdd->list);
|
|
+ return -ENOMEM;
|
|
+ }
|
|
+
|
|
+ /*
|
|
+ * CAP_SYS_ADMIN for getxattr
|
|
+ * CAP_DAC_OVERRIDE for lookup
|
|
+ */
|
|
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
|
|
+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
|
|
+ old_cred = override_creds(override_cred);
|
|
+
|
|
+ mutex_lock(&rdd->dir->d_inode->i_mutex);
|
|
+ list_for_each_entry(p, rdd->list, l_node) {
|
|
+ if (p->type != DT_LNK)
|
|
+ continue;
|
|
+
|
|
+ dentry = lookup_one_len(p->name, rdd->dir, p->len);
|
|
+ if (IS_ERR(dentry))
|
|
+ continue;
|
|
+
|
|
+ p->is_whiteout = ovl_is_whiteout(dentry);
|
|
+ dput(dentry);
|
|
+ }
|
|
+ mutex_unlock(&rdd->dir->d_inode->i_mutex);
|
|
+
|
|
+ revert_creds(old_cred);
|
|
+ put_cred(override_cred);
|
|
+
|
|
+ return 0;
|
|
+}
|
|
+
|
|
+static inline int ovl_dir_read_merged(struct path *upperpath,
|
|
+ struct path *lowerpath,
|
|
+ struct list_head *list)
|
|
+{
|
|
+ int err;
|
|
+ struct rb_root root = RB_ROOT;
|
|
+ struct list_head middle;
|
|
+ struct ovl_readdir_data rdd = {
|
|
+ .ctx.actor = ovl_fill_merge,
|
|
+ .list = list,
|
|
+ .root = &root,
|
|
+ .is_merge = false,
|
|
+ };
|
|
+
|
|
+ if (upperpath->dentry) {
|
|
+ rdd.dir = upperpath->dentry;
|
|
+ err = ovl_dir_read(upperpath, &rdd);
|
|
+ if (err)
|
|
+ goto out;
|
|
+
|
|
+ err = ovl_dir_mark_whiteouts(&rdd);
|
|
+ if (err)
|
|
+ goto out;
|
|
+ }
|
|
+ /*
|
|
+ * Insert lowerpath entries before upperpath ones, this allows
|
|
+ * offsets to be reasonably constant
|
|
+ */
|
|
+ list_add(&middle, rdd.list);
|
|
+ rdd.middle = &middle;
|
|
+ rdd.is_merge = true;
|
|
+ err = ovl_dir_read(lowerpath, &rdd);
|
|
+ list_del(&middle);
|
|
+out:
|
|
+ return err;
|
|
+}
|
|
+
|
|
+static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
|
|
+{
|
|
+ struct list_head *l;
|
|
+ loff_t off;
|
|
+
|
|
+ l = od->cache.next;
|
|
+ for (off = 0; off < pos; off++) {
|
|
+ if (l == &od->cache)
|
|
+ break;
|
|
+ l = l->next;
|
|
+ }
|
|
+ list_move_tail(&od->cursor, l);
|
|
+}
|
|
+
|
|
+static int ovl_iterate(struct file *file, struct dir_context *ctx)
|
|
+{
|
|
+ struct ovl_dir_file *od = file->private_data;
|
|
+ int res;
|
|
+
|
|
+ if (!ctx->pos)
|
|
+ ovl_dir_reset(file);
|
|
+
|
|
+ if (od->is_real) {
|
|
+ res = iterate_dir(od->realfile, ctx);
|
|
+
|
|
+ return res;
|
|
+ }
|
|
+
|
|
+ if (!od->is_cached) {
|
|
+ struct path lowerpath;
|
|
+ struct path upperpath;
|
|
+
|
|
+ ovl_path_lower(file->f_path.dentry, &lowerpath);
|
|
+ ovl_path_upper(file->f_path.dentry, &upperpath);
|
|
+
|
|
+ res = ovl_dir_read_merged(&upperpath, &lowerpath, &od->cache);
|
|
+ if (res) {
|
|
+ ovl_cache_free(&od->cache);
|
|
+ return res;
|
|
+ }
|
|
+
|
|
+ od->cache_version = ovl_dentry_version_get(file->f_path.dentry);
|
|
+ od->is_cached = true;
|
|
+
|
|
+ ovl_seek_cursor(od, ctx->pos);
|
|
+ }
|
|
+
|
|
+ while (od->cursor.next != &od->cache) {
|
|
+ struct ovl_cache_entry *p;
|
|
+
|
|
+ p = list_entry(od->cursor.next, struct ovl_cache_entry, l_node);
|
|
+ if (!p->is_whiteout) {
|
|
+ if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
|
|
+ break;
|
|
+ }
|
|
+ ctx->pos++;
|
|
+ list_move(&od->cursor, &p->l_node);
|
|
+ }
|
|
+
|
|
+ return 0;
|
|
+}
|
|
+
|
|
+static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
|
|
+{
|
|
+ loff_t res;
|
|
+ struct ovl_dir_file *od = file->private_data;
|
|
+
|
|
+ mutex_lock(&file_inode(file)->i_mutex);
|
|
+ if (!file->f_pos)
|
|
+ ovl_dir_reset(file);
|
|
+
|
|
+ if (od->is_real) {
|
|
+ res = vfs_llseek(od->realfile, offset, origin);
|
|
+ file->f_pos = od->realfile->f_pos;
|
|
+ } else {
|
|
+ res = -EINVAL;
|
|
+
|
|
+ switch (origin) {
|
|
+ case SEEK_CUR:
|
|
+ offset += file->f_pos;
|
|
+ break;
|
|
+ case SEEK_SET:
|
|
+ break;
|
|
+ default:
|
|
+ goto out_unlock;
|
|
+ }
|
|
+ if (offset < 0)
|
|
+ goto out_unlock;
|
|
+
|
|
+ if (offset != file->f_pos) {
|
|
+ file->f_pos = offset;
|
|
+ if (od->is_cached)
|
|
+ ovl_seek_cursor(od, offset);
|
|
+ }
|
|
+ res = offset;
|
|
+ }
|
|
+out_unlock:
|
|
+ mutex_unlock(&file_inode(file)->i_mutex);
|
|
+
|
|
+ return res;
|
|
+}
|
|
+
|
|
+static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
|
|
+ int datasync)
|
|
+{
|
|
+ struct ovl_dir_file *od = file->private_data;
|
|
+
|
|
+ /* May need to reopen directory if it got copied up */
|
|
+ if (!od->realfile) {
|
|
+ struct path upperpath;
|
|
+
|
|
+ ovl_path_upper(file->f_path.dentry, &upperpath);
|
|
+ od->realfile = ovl_path_open(&upperpath, O_RDONLY);
|
|
+ if (IS_ERR(od->realfile))
|
|
+ return PTR_ERR(od->realfile);
|
|
+ }
|
|
+
|
|
+ return vfs_fsync_range(od->realfile, start, end, datasync);
|
|
+}
|
|
+
|
|
+static int ovl_dir_release(struct inode *inode, struct file *file)
|
|
+{
|
|
+ struct ovl_dir_file *od = file->private_data;
|
|
+
|
|
+ list_del(&od->cursor);
|
|
+ ovl_cache_free(&od->cache);
|
|
+ if (od->realfile)
|
|
+ fput(od->realfile);
|
|
+ kfree(od);
|
|
+
|
|
+ return 0;
|
|
+}
|
|
+
|
|
+static int ovl_dir_open(struct inode *inode, struct file *file)
|
|
+{
|
|
+ struct path realpath;
|
|
+ struct file *realfile;
|
|
+ struct ovl_dir_file *od;
|
|
+ enum ovl_path_type type;
|
|
+
|
|
+ od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL);
|
|
+ if (!od)
|
|
+ return -ENOMEM;
|
|
+
|
|
+ type = ovl_path_real(file->f_path.dentry, &realpath);
|
|
+ realfile = ovl_path_open(&realpath, file->f_flags);
|
|
+ if (IS_ERR(realfile)) {
|
|
+ kfree(od);
|
|
+ return PTR_ERR(realfile);
|
|
+ }
|
|
+ INIT_LIST_HEAD(&od->cache);
|
|
+ INIT_LIST_HEAD(&od->cursor);
|
|
+ od->is_cached = false;
|
|
+ od->realfile = realfile;
|
|
+ od->is_real = (type != OVL_PATH_MERGE);
|
|
+ file->private_data = od;
|
|
+
|
|
+ return 0;
|
|
+}
|
|
+
|
|
+const struct file_operations ovl_dir_operations = {
|
|
+ .read = generic_read_dir,
|
|
+ .open = ovl_dir_open,
|
|
+ .iterate = ovl_iterate,
|
|
+ .llseek = ovl_dir_llseek,
|
|
+ .fsync = ovl_dir_fsync,
|
|
+ .release = ovl_dir_release,
|
|
+};
|
|
+
|
|
+static int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
|
|
+{
|
|
+ int err;
|
|
+ struct path lowerpath;
|
|
+ struct path upperpath;
|
|
+ struct ovl_cache_entry *p;
|
|
+
|
|
+ ovl_path_upper(dentry, &upperpath);
|
|
+ ovl_path_lower(dentry, &lowerpath);
|
|
+
|
|
+ err = ovl_dir_read_merged(&upperpath, &lowerpath, list);
|
|
+ if (err)
|
|
+ return err;
|
|
+
|
|
+ err = 0;
|
|
+
|
|
+ list_for_each_entry(p, list, l_node) {
|
|
+ if (p->is_whiteout)
|
|
+ continue;
|
|
+
|
|
+ if (p->name[0] == '.') {
|
|
+ if (p->len == 1)
|
|
+ continue;
|
|
+ if (p->len == 2 && p->name[1] == '.')
|
|
+ continue;
|
|
+ }
|
|
+ err = -ENOTEMPTY;
|
|
+ break;
|
|
+ }
|
|
+
|
|
+ return err;
|
|
+}
|
|
+
|
|
+static int ovl_remove_whiteouts(struct dentry *dir, struct list_head *list)
|
|
+{
|
|
+ struct path upperpath;
|
|
+ struct dentry *upperdir;
|
|
+ struct ovl_cache_entry *p;
|
|
+ const struct cred *old_cred;
|
|
+ struct cred *override_cred;
|
|
+ int err;
|
|
+
|
|
+ ovl_path_upper(dir, &upperpath);
|
|
+ upperdir = upperpath.dentry;
|
|
+
|
|
+ override_cred = prepare_creds();
|
|
+ if (!override_cred)
|
|
+ return -ENOMEM;
|
|
+
|
|
+ /*
|
|
+ * CAP_DAC_OVERRIDE for lookup and unlink
|
|
+ * CAP_SYS_ADMIN for setxattr of "trusted" namespace
|
|
+ * CAP_FOWNER for unlink in sticky directory
|
|
+ */
|
|
+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
|
|
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
|
|
+ cap_raise(override_cred->cap_effective, CAP_FOWNER);
|
|
+ old_cred = override_creds(override_cred);
|
|
+
|
|
+ err = vfs_setxattr(upperdir, ovl_opaque_xattr, "y", 1, 0);
|
|
+ if (err)
|
|
+ goto out_revert_creds;
|
|
+
|
|
+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
+ list_for_each_entry(p, list, l_node) {
|
|
+ struct dentry *dentry;
|
|
+ int ret;
|
|
+
|
|
+ if (!p->is_whiteout)
|
|
+ continue;
|
|
+
|
|
+ dentry = lookup_one_len(p->name, upperdir, p->len);
|
|
+ if (IS_ERR(dentry)) {
|
|
+ pr_warn(
|
|
+ "overlayfs: failed to lookup whiteout %.*s: %li\n",
|
|
+ p->len, p->name, PTR_ERR(dentry));
|
|
+ continue;
|
|
+ }
|
|
+ ret = vfs_unlink(upperdir->d_inode, dentry, NULL);
|
|
+ dput(dentry);
|
|
+ if (ret)
|
|
+ pr_warn(
|
|
+ "overlayfs: failed to unlink whiteout %.*s: %i\n",
|
|
+ p->len, p->name, ret);
|
|
+ }
|
|
+ mutex_unlock(&upperdir->d_inode->i_mutex);
|
|
+
|
|
+out_revert_creds:
|
|
+ revert_creds(old_cred);
|
|
+ put_cred(override_cred);
|
|
+
|
|
+ return err;
|
|
+}
|
|
+
|
|
+int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type)
|
|
+{
|
|
+ int err;
|
|
+ LIST_HEAD(list);
|
|
+
|
|
+ err = ovl_check_empty_dir(dentry, &list);
|
|
+ if (!err && type == OVL_PATH_MERGE)
|
|
+ err = ovl_remove_whiteouts(dentry, &list);
|
|
+
|
|
+ ovl_cache_free(&list);
|
|
+
|
|
+ return err;
|
|
+}
|
|
--- /dev/null
|
|
+++ b/fs/overlayfs/super.c
|
|
@@ -0,0 +1,685 @@
|
|
+/*
|
|
+ *
|
|
+ * Copyright (C) 2011 Novell Inc.
|
|
+ *
|
|
+ * This program is free software; you can redistribute it and/or modify it
|
|
+ * under the terms of the GNU General Public License version 2 as published by
|
|
+ * the Free Software Foundation.
|
|
+ */
|
|
+
|
|
+#include <linux/fs.h>
|
|
+#include <linux/namei.h>
|
|
+#include <linux/xattr.h>
|
|
+#include <linux/security.h>
|
|
+#include <linux/mount.h>
|
|
+#include <linux/slab.h>
|
|
+#include <linux/parser.h>
|
|
+#include <linux/module.h>
|
|
+#include <linux/cred.h>
|
|
+#include <linux/sched.h>
|
|
+#include <linux/statfs.h>
|
|
+#include <linux/seq_file.h>
|
|
+#include "overlayfs.h"
|
|
+
|
|
+MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
|
|
+MODULE_DESCRIPTION("Overlay filesystem");
|
|
+MODULE_LICENSE("GPL");
|
|
+
|
|
+#define OVERLAYFS_SUPER_MAGIC 0x794c764f
|
|
+
|
|
+struct ovl_config {
|
|
+ char *lowerdir;
|
|
+ char *upperdir;
|
|
+};
|
|
+
|
|
+/* private information held for overlayfs's superblock */
|
|
+struct ovl_fs {
|
|
+ struct vfsmount *upper_mnt;
|
|
+ struct vfsmount *lower_mnt;
|
|
+ long lower_namelen;
|
|
+ /* pathnames of lower and upper dirs, for show_options */
|
|
+ struct ovl_config config;
|
|
+};
|
|
+
|
|
+/* private information held for every overlayfs dentry */
|
|
+struct ovl_entry {
|
|
+ /*
|
|
+ * Keep "double reference" on upper dentries, so that
|
|
+ * d_delete() doesn't think it's OK to reset d_inode to NULL.
|
|
+ */
|
|
+ struct dentry *__upperdentry;
|
|
+ struct dentry *lowerdentry;
|
|
+ union {
|
|
+ struct {
|
|
+ u64 version;
|
|
+ bool opaque;
|
|
+ };
|
|
+ struct rcu_head rcu;
|
|
+ };
|
|
+};
|
|
+
|
|
+const char *ovl_whiteout_xattr = "trusted.overlay.whiteout";
|
|
+const char *ovl_opaque_xattr = "trusted.overlay.opaque";
|
|
+
|
|
+
|
|
+enum ovl_path_type ovl_path_type(struct dentry *dentry)
|
|
+{
|
|
+ struct ovl_entry *oe = dentry->d_fsdata;
|
|
+
|
|
+ if (oe->__upperdentry) {
|
|
+ if (oe->lowerdentry && S_ISDIR(dentry->d_inode->i_mode))
|
|
+ return OVL_PATH_MERGE;
|
|
+ else
|
|
+ return OVL_PATH_UPPER;
|
|
+ } else {
|
|
+ return OVL_PATH_LOWER;
|
|
+ }
|
|
+}
|
|
+
|
|
+static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
|
|
+{
|
|
+ struct dentry *upperdentry = ACCESS_ONCE(oe->__upperdentry);
|
|
+ smp_read_barrier_depends();
|
|
+ return upperdentry;
|
|
+}
|
|
+
|
|
+void ovl_path_upper(struct dentry *dentry, struct path *path)
|
|
+{
|
|
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
|
|
+ struct ovl_entry *oe = dentry->d_fsdata;
|
|
+
|
|
+ path->mnt = ofs->upper_mnt;
|
|
+ path->dentry = ovl_upperdentry_dereference(oe);
|
|
+}
|
|
+
|
|
+void ovl_path_lower(struct dentry *dentry, struct path *path)
|
|
+{
|
|
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
|
|
+ struct ovl_entry *oe = dentry->d_fsdata;
|
|
+
|
|
+ path->mnt = ofs->lower_mnt;
|
|
+ path->dentry = oe->lowerdentry;
|
|
+}
|
|
+
|
|
+enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
|
|
+{
|
|
+
|
|
+ enum ovl_path_type type = ovl_path_type(dentry);
|
|
+
|
|
+ if (type == OVL_PATH_LOWER)
|
|
+ ovl_path_lower(dentry, path);
|
|
+ else
|
|
+ ovl_path_upper(dentry, path);
|
|
+
|
|
+ return type;
|
|
+}
|
|
+
|
|
+struct dentry *ovl_dentry_upper(struct dentry *dentry)
|
|
+{
|
|
+ struct ovl_entry *oe = dentry->d_fsdata;
|
|
+
|
|
+ return ovl_upperdentry_dereference(oe);
|
|
+}
|
|
+
|
|
+struct dentry *ovl_dentry_lower(struct dentry *dentry)
|
|
+{
|
|
+ struct ovl_entry *oe = dentry->d_fsdata;
|
|
+
|
|
+ return oe->lowerdentry;
|
|
+}
|
|
+
|
|
+struct dentry *ovl_dentry_real(struct dentry *dentry)
|
|
+{
|
|
+ struct ovl_entry *oe = dentry->d_fsdata;
|
|
+ struct dentry *realdentry;
|
|
+
|
|
+ realdentry = ovl_upperdentry_dereference(oe);
|
|
+ if (!realdentry)
|
|
+ realdentry = oe->lowerdentry;
|
|
+
|
|
+ return realdentry;
|
|
+}
|
|
+
|
|
+struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper)
|
|
+{
|
|
+ struct dentry *realdentry;
|
|
+
|
|
+ realdentry = ovl_upperdentry_dereference(oe);
|
|
+ if (realdentry) {
|
|
+ *is_upper = true;
|
|
+ } else {
|
|
+ realdentry = oe->lowerdentry;
|
|
+ *is_upper = false;
|
|
+ }
|
|
+ return realdentry;
|
|
+}
|
|
+
|
|
+bool ovl_dentry_is_opaque(struct dentry *dentry)
|
|
+{
|
|
+ struct ovl_entry *oe = dentry->d_fsdata;
|
|
+ return oe->opaque;
|
|
+}
|
|
+
|
|
+void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque)
|
|
+{
|
|
+ struct ovl_entry *oe = dentry->d_fsdata;
|
|
+ oe->opaque = opaque;
|
|
+}
|
|
+
|
|
+void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
|
|
+{
|
|
+ struct ovl_entry *oe = dentry->d_fsdata;
|
|
+
|
|
+ WARN_ON(!mutex_is_locked(&upperdentry->d_parent->d_inode->i_mutex));
|
|
+ WARN_ON(oe->__upperdentry);
|
|
+ BUG_ON(!upperdentry->d_inode);
|
|
+ smp_wmb();
|
|
+ oe->__upperdentry = dget(upperdentry);
|
|
+}
|
|
+
|
|
+void ovl_dentry_version_inc(struct dentry *dentry)
|
|
+{
|
|
+ struct ovl_entry *oe = dentry->d_fsdata;
|
|
+
|
|
+ WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
|
|
+ oe->version++;
|
|
+}
|
|
+
|
|
+u64 ovl_dentry_version_get(struct dentry *dentry)
|
|
+{
|
|
+ struct ovl_entry *oe = dentry->d_fsdata;
|
|
+
|
|
+ WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
|
|
+ return oe->version;
|
|
+}
|
|
+
|
|
+bool ovl_is_whiteout(struct dentry *dentry)
|
|
+{
|
|
+ int res;
|
|
+ char val;
|
|
+
|
|
+ if (!dentry)
|
|
+ return false;
|
|
+ if (!dentry->d_inode)
|
|
+ return false;
|
|
+ if (!S_ISLNK(dentry->d_inode->i_mode))
|
|
+ return false;
|
|
+
|
|
+ res = vfs_getxattr(dentry, ovl_whiteout_xattr, &val, 1);
|
|
+ if (res == 1 && val == 'y')
|
|
+ return true;
|
|
+
|
|
+ return false;
|
|
+}
|
|
+
|
|
+static bool ovl_is_opaquedir(struct dentry *dentry)
|
|
+{
|
|
+ int res;
|
|
+ char val;
|
|
+
|
|
+ if (!S_ISDIR(dentry->d_inode->i_mode))
|
|
+ return false;
|
|
+
|
|
+ res = vfs_getxattr(dentry, ovl_opaque_xattr, &val, 1);
|
|
+ if (res == 1 && val == 'y')
|
|
+ return true;
|
|
+
|
|
+ return false;
|
|
+}
|
|
+
|
|
+static void ovl_entry_free(struct rcu_head *head)
|
|
+{
|
|
+ struct ovl_entry *oe = container_of(head, struct ovl_entry, rcu);
|
|
+ kfree(oe);
|
|
+}
|
|
+
|
|
+static void ovl_dentry_release(struct dentry *dentry)
|
|
+{
|
|
+ struct ovl_entry *oe = dentry->d_fsdata;
|
|
+
|
|
+ if (oe) {
|
|
+ dput(oe->__upperdentry);
|
|
+ dput(oe->__upperdentry);
|
|
+ dput(oe->lowerdentry);
|
|
+ call_rcu(&oe->rcu, ovl_entry_free);
|
|
+ }
|
|
+}
|
|
+
|
|
+const struct dentry_operations ovl_dentry_operations = {
|
|
+ .d_release = ovl_dentry_release,
|
|
+};
|
|
+
|
|
+static struct ovl_entry *ovl_alloc_entry(void)
|
|
+{
|
|
+ return kzalloc(sizeof(struct ovl_entry), GFP_KERNEL);
|
|
+}
|
|
+
|
|
+static inline struct dentry *ovl_lookup_real(struct dentry *dir,
|
|
+ struct qstr *name)
|
|
+{
|
|
+ struct dentry *dentry;
|
|
+
|
|
+ mutex_lock(&dir->d_inode->i_mutex);
|
|
+ dentry = lookup_one_len(name->name, dir, name->len);
|
|
+ mutex_unlock(&dir->d_inode->i_mutex);
|
|
+
|
|
+ if (IS_ERR(dentry)) {
|
|
+ if (PTR_ERR(dentry) == -ENOENT)
|
|
+ dentry = NULL;
|
|
+ } else if (!dentry->d_inode) {
|
|
+ dput(dentry);
|
|
+ dentry = NULL;
|
|
+ }
|
|
+ return dentry;
|
|
+}
|
|
+
|
|
+static int ovl_do_lookup(struct dentry *dentry)
|
|
+{
|
|
+ struct ovl_entry *oe;
|
|
+ struct dentry *upperdir;
|
|
+ struct dentry *lowerdir;
|
|
+ struct dentry *upperdentry = NULL;
|
|
+ struct dentry *lowerdentry = NULL;
|
|
+ struct inode *inode = NULL;
|
|
+ int err;
|
|
+
|
|
+ err = -ENOMEM;
|
|
+ oe = ovl_alloc_entry();
|
|
+ if (!oe)
|
|
+ goto out;
|
|
+
|
|
+ upperdir = ovl_dentry_upper(dentry->d_parent);
|
|
+ lowerdir = ovl_dentry_lower(dentry->d_parent);
|
|
+
|
|
+ if (upperdir) {
|
|
+ upperdentry = ovl_lookup_real(upperdir, &dentry->d_name);
|
|
+ err = PTR_ERR(upperdentry);
|
|
+ if (IS_ERR(upperdentry))
|
|
+ goto out_put_dir;
|
|
+
|
|
+ if (lowerdir && upperdentry &&
|
|
+ (S_ISLNK(upperdentry->d_inode->i_mode) ||
|
|
+ S_ISDIR(upperdentry->d_inode->i_mode))) {
|
|
+ const struct cred *old_cred;
|
|
+ struct cred *override_cred;
|
|
+
|
|
+ err = -ENOMEM;
|
|
+ override_cred = prepare_creds();
|
|
+ if (!override_cred)
|
|
+ goto out_dput_upper;
|
|
+
|
|
+ /* CAP_SYS_ADMIN needed for getxattr */
|
|
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
|
|
+ old_cred = override_creds(override_cred);
|
|
+
|
|
+ if (ovl_is_opaquedir(upperdentry)) {
|
|
+ oe->opaque = true;
|
|
+ } else if (ovl_is_whiteout(upperdentry)) {
|
|
+ dput(upperdentry);
|
|
+ upperdentry = NULL;
|
|
+ oe->opaque = true;
|
|
+ }
|
|
+ revert_creds(old_cred);
|
|
+ put_cred(override_cred);
|
|
+ }
|
|
+ }
|
|
+ if (lowerdir && !oe->opaque) {
|
|
+ lowerdentry = ovl_lookup_real(lowerdir, &dentry->d_name);
|
|
+ err = PTR_ERR(lowerdentry);
|
|
+ if (IS_ERR(lowerdentry))
|
|
+ goto out_dput_upper;
|
|
+ }
|
|
+
|
|
+ if (lowerdentry && upperdentry &&
|
|
+ (!S_ISDIR(upperdentry->d_inode->i_mode) ||
|
|
+ !S_ISDIR(lowerdentry->d_inode->i_mode))) {
|
|
+ dput(lowerdentry);
|
|
+ lowerdentry = NULL;
|
|
+ oe->opaque = true;
|
|
+ }
|
|
+
|
|
+ if (lowerdentry || upperdentry) {
|
|
+ struct dentry *realdentry;
|
|
+
|
|
+ realdentry = upperdentry ? upperdentry : lowerdentry;
|
|
+ err = -ENOMEM;
|
|
+ inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode,
|
|
+ oe);
|
|
+ if (!inode)
|
|
+ goto out_dput;
|
|
+ ovl_copyattr(realdentry->d_inode, inode);
|
|
+ }
|
|
+
|
|
+ if (upperdentry)
|
|
+ oe->__upperdentry = dget(upperdentry);
|
|
+
|
|
+ if (lowerdentry)
|
|
+ oe->lowerdentry = lowerdentry;
|
|
+
|
|
+ dentry->d_fsdata = oe;
|
|
+ dentry->d_op = &ovl_dentry_operations;
|
|
+ d_add(dentry, inode);
|
|
+
|
|
+ return 0;
|
|
+
|
|
+out_dput:
|
|
+ dput(lowerdentry);
|
|
+out_dput_upper:
|
|
+ dput(upperdentry);
|
|
+out_put_dir:
|
|
+ kfree(oe);
|
|
+out:
|
|
+ return err;
|
|
+}
|
|
+
|
|
+struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
|
|
+ unsigned int flags)
|
|
+{
|
|
+ int err = ovl_do_lookup(dentry);
|
|
+
|
|
+ if (err)
|
|
+ return ERR_PTR(err);
|
|
+
|
|
+ return NULL;
|
|
+}
|
|
+
|
|
+struct file *ovl_path_open(struct path *path, int flags)
|
|
+{
|
|
+ return dentry_open(path, flags, current_cred());
|
|
+}
|
|
+
|
|
+static void ovl_put_super(struct super_block *sb)
|
|
+{
|
|
+ struct ovl_fs *ufs = sb->s_fs_info;
|
|
+
|
|
+ if (!(sb->s_flags & MS_RDONLY))
|
|
+ mnt_drop_write(ufs->upper_mnt);
|
|
+
|
|
+ mntput(ufs->upper_mnt);
|
|
+ mntput(ufs->lower_mnt);
|
|
+
|
|
+ kfree(ufs->config.lowerdir);
|
|
+ kfree(ufs->config.upperdir);
|
|
+ kfree(ufs);
|
|
+}
|
|
+
|
|
+static int ovl_remount_fs(struct super_block *sb, int *flagsp, char *data)
|
|
+{
|
|
+ int flags = *flagsp;
|
|
+ struct ovl_fs *ufs = sb->s_fs_info;
|
|
+
|
|
+ /* When remounting rw or ro, we need to adjust the write access to the
|
|
+ * upper fs.
|
|
+ */
|
|
+ if (((flags ^ sb->s_flags) & MS_RDONLY) == 0)
|
|
+ /* No change to readonly status */
|
|
+ return 0;
|
|
+
|
|
+ if (flags & MS_RDONLY) {
|
|
+ mnt_drop_write(ufs->upper_mnt);
|
|
+ return 0;
|
|
+ } else
|
|
+ return mnt_want_write(ufs->upper_mnt);
|
|
+}
|
|
+
|
|
+/**
|
|
+ * ovl_statfs
|
|
+ * @sb: The overlayfs super block
|
|
+ * @buf: The struct kstatfs to fill in with stats
|
|
+ *
|
|
+ * Get the filesystem statistics. As writes always target the upper layer
|
|
+ * filesystem pass the statfs to the same filesystem.
|
|
+ */
|
|
+static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
|
|
+{
|
|
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
|
|
+ struct dentry *root_dentry = dentry->d_sb->s_root;
|
|
+ struct path path;
|
|
+ int err;
|
|
+
|
|
+ ovl_path_upper(root_dentry, &path);
|
|
+
|
|
+ err = vfs_statfs(&path, buf);
|
|
+ if (!err) {
|
|
+ buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen);
|
|
+ buf->f_type = OVERLAYFS_SUPER_MAGIC;
|
|
+ }
|
|
+
|
|
+ return err;
|
|
+}
|
|
+
|
|
+/**
|
|
+ * ovl_show_options
|
|
+ *
|
|
+ * Prints the mount options for a given superblock.
|
|
+ * Returns zero; does not fail.
|
|
+ */
|
|
+static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
|
|
+{
|
|
+ struct super_block *sb = dentry->d_sb;
|
|
+ struct ovl_fs *ufs = sb->s_fs_info;
|
|
+
|
|
+ seq_printf(m, ",lowerdir=%s", ufs->config.lowerdir);
|
|
+ seq_printf(m, ",upperdir=%s", ufs->config.upperdir);
|
|
+ return 0;
|
|
+}
|
|
+
|
|
+static const struct super_operations ovl_super_operations = {
|
|
+ .put_super = ovl_put_super,
|
|
+ .remount_fs = ovl_remount_fs,
|
|
+ .statfs = ovl_statfs,
|
|
+ .show_options = ovl_show_options,
|
|
+};
|
|
+
|
|
+enum {
|
|
+ OPT_LOWERDIR,
|
|
+ OPT_UPPERDIR,
|
|
+ OPT_ERR,
|
|
+};
|
|
+
|
|
+static const match_table_t ovl_tokens = {
|
|
+ {OPT_LOWERDIR, "lowerdir=%s"},
|
|
+ {OPT_UPPERDIR, "upperdir=%s"},
|
|
+ {OPT_ERR, NULL}
|
|
+};
|
|
+
|
|
+static int ovl_parse_opt(char *opt, struct ovl_config *config)
|
|
+{
|
|
+ char *p;
|
|
+
|
|
+ config->upperdir = NULL;
|
|
+ config->lowerdir = NULL;
|
|
+
|
|
+ while ((p = strsep(&opt, ",")) != NULL) {
|
|
+ int token;
|
|
+ substring_t args[MAX_OPT_ARGS];
|
|
+
|
|
+ if (!*p)
|
|
+ continue;
|
|
+
|
|
+ token = match_token(p, ovl_tokens, args);
|
|
+ switch (token) {
|
|
+ case OPT_UPPERDIR:
|
|
+ kfree(config->upperdir);
|
|
+ config->upperdir = match_strdup(&args[0]);
|
|
+ if (!config->upperdir)
|
|
+ return -ENOMEM;
|
|
+ break;
|
|
+
|
|
+ case OPT_LOWERDIR:
|
|
+ kfree(config->lowerdir);
|
|
+ config->lowerdir = match_strdup(&args[0]);
|
|
+ if (!config->lowerdir)
|
|
+ return -ENOMEM;
|
|
+ break;
|
|
+
|
|
+ default:
|
|
+ return -EINVAL;
|
|
+ }
|
|
+ }
|
|
+ return 0;
|
|
+}
|
|
+
|
|
+static int ovl_fill_super(struct super_block *sb, void *data, int silent)
|
|
+{
|
|
+ struct path lowerpath;
|
|
+ struct path upperpath;
|
|
+ struct inode *root_inode;
|
|
+ struct dentry *root_dentry;
|
|
+ struct ovl_entry *oe;
|
|
+ struct ovl_fs *ufs;
|
|
+ struct kstatfs statfs;
|
|
+ int err;
|
|
+
|
|
+ err = -ENOMEM;
|
|
+ ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL);
|
|
+ if (!ufs)
|
|
+ goto out;
|
|
+
|
|
+ err = ovl_parse_opt((char *) data, &ufs->config);
|
|
+ if (err)
|
|
+ goto out_free_ufs;
|
|
+
|
|
+ err = -EINVAL;
|
|
+ if (!ufs->config.upperdir || !ufs->config.lowerdir) {
|
|
+ pr_err("overlayfs: missing upperdir or lowerdir\n");
|
|
+ goto out_free_config;
|
|
+ }
|
|
+
|
|
+ oe = ovl_alloc_entry();
|
|
+ if (oe == NULL)
|
|
+ goto out_free_config;
|
|
+
|
|
+ err = kern_path(ufs->config.upperdir, LOOKUP_FOLLOW, &upperpath);
|
|
+ if (err)
|
|
+ goto out_free_oe;
|
|
+
|
|
+ err = kern_path(ufs->config.lowerdir, LOOKUP_FOLLOW, &lowerpath);
|
|
+ if (err)
|
|
+ goto out_put_upperpath;
|
|
+
|
|
+ err = -ENOTDIR;
|
|
+ if (!S_ISDIR(upperpath.dentry->d_inode->i_mode) ||
|
|
+ !S_ISDIR(lowerpath.dentry->d_inode->i_mode))
|
|
+ goto out_put_lowerpath;
|
|
+
|
|
+ err = vfs_statfs(&lowerpath, &statfs);
|
|
+ if (err) {
|
|
+ pr_err("overlayfs: statfs failed on lowerpath\n");
|
|
+ goto out_put_lowerpath;
|
|
+ }
|
|
+ ufs->lower_namelen = statfs.f_namelen;
|
|
+
|
|
+ sb->s_stack_depth = max(upperpath.mnt->mnt_sb->s_stack_depth,
|
|
+ lowerpath.mnt->mnt_sb->s_stack_depth) + 1;
|
|
+
|
|
+ err = -EINVAL;
|
|
+ if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
|
|
+ pr_err("overlayfs: maximum fs stacking depth exceeded\n");
|
|
+ goto out_put_lowerpath;
|
|
+ }
|
|
+
|
|
+
|
|
+ ufs->upper_mnt = clone_private_mount(&upperpath);
|
|
+ err = PTR_ERR(ufs->upper_mnt);
|
|
+ if (IS_ERR(ufs->upper_mnt)) {
|
|
+ pr_err("overlayfs: failed to clone upperpath\n");
|
|
+ goto out_put_lowerpath;
|
|
+ }
|
|
+
|
|
+ ufs->lower_mnt = clone_private_mount(&lowerpath);
|
|
+ err = PTR_ERR(ufs->lower_mnt);
|
|
+ if (IS_ERR(ufs->lower_mnt)) {
|
|
+ pr_err("overlayfs: failed to clone lowerpath\n");
|
|
+ goto out_put_upper_mnt;
|
|
+ }
|
|
+
|
|
+ /*
|
|
+ * Make lower_mnt R/O. That way fchmod/fchown on lower file
|
|
+ * will fail instead of modifying lower fs.
|
|
+ */
|
|
+ ufs->lower_mnt->mnt_flags |= MNT_READONLY;
|
|
+
|
|
+ /* If the upper fs is r/o, we mark overlayfs r/o too */
|
|
+ if (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY)
|
|
+ sb->s_flags |= MS_RDONLY;
|
|
+
|
|
+ if (!(sb->s_flags & MS_RDONLY)) {
|
|
+ err = mnt_want_write(ufs->upper_mnt);
|
|
+ if (err)
|
|
+ goto out_put_lower_mnt;
|
|
+ }
|
|
+
|
|
+ err = -ENOMEM;
|
|
+ root_inode = ovl_new_inode(sb, S_IFDIR, oe);
|
|
+ if (!root_inode)
|
|
+ goto out_drop_write;
|
|
+
|
|
+ root_dentry = d_make_root(root_inode);
|
|
+ if (!root_dentry)
|
|
+ goto out_drop_write;
|
|
+
|
|
+ mntput(upperpath.mnt);
|
|
+ mntput(lowerpath.mnt);
|
|
+
|
|
+ oe->__upperdentry = dget(upperpath.dentry);
|
|
+ oe->lowerdentry = lowerpath.dentry;
|
|
+
|
|
+ root_dentry->d_fsdata = oe;
|
|
+ root_dentry->d_op = &ovl_dentry_operations;
|
|
+
|
|
+ sb->s_magic = OVERLAYFS_SUPER_MAGIC;
|
|
+ sb->s_op = &ovl_super_operations;
|
|
+ sb->s_root = root_dentry;
|
|
+ sb->s_fs_info = ufs;
|
|
+
|
|
+ return 0;
|
|
+
|
|
+out_drop_write:
|
|
+ if (!(sb->s_flags & MS_RDONLY))
|
|
+ mnt_drop_write(ufs->upper_mnt);
|
|
+out_put_lower_mnt:
|
|
+ mntput(ufs->lower_mnt);
|
|
+out_put_upper_mnt:
|
|
+ mntput(ufs->upper_mnt);
|
|
+out_put_lowerpath:
|
|
+ path_put(&lowerpath);
|
|
+out_put_upperpath:
|
|
+ path_put(&upperpath);
|
|
+out_free_oe:
|
|
+ kfree(oe);
|
|
+out_free_config:
|
|
+ kfree(ufs->config.lowerdir);
|
|
+ kfree(ufs->config.upperdir);
|
|
+out_free_ufs:
|
|
+ kfree(ufs);
|
|
+out:
|
|
+ return err;
|
|
+}
|
|
+
|
|
+static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
|
|
+ const char *dev_name, void *raw_data)
|
|
+{
|
|
+ return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
|
|
+}
|
|
+
|
|
+static struct file_system_type ovl_fs_type = {
|
|
+ .owner = THIS_MODULE,
|
|
+ .name = "overlayfs",
|
|
+ .mount = ovl_mount,
|
|
+ .kill_sb = kill_anon_super,
|
|
+};
|
|
+MODULE_ALIAS_FS("overlayfs");
|
|
+
|
|
+static int __init ovl_init(void)
|
|
+{
|
|
+ return register_filesystem(&ovl_fs_type);
|
|
+}
|
|
+
|
|
+static void __exit ovl_exit(void)
|
|
+{
|
|
+ unregister_filesystem(&ovl_fs_type);
|
|
+}
|
|
+
|
|
+module_init(ovl_init);
|
|
+module_exit(ovl_exit);
|
|
--- a/fs/splice.c
|
|
+++ b/fs/splice.c
|
|
@@ -1327,6 +1327,7 @@ long do_splice_direct(struct file *in, l
|
|
|
|
return ret;
|
|
}
|
|
+EXPORT_SYMBOL(do_splice_direct);
|
|
|
|
static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
|
|
struct pipe_inode_info *opipe,
|
|
--- a/include/linux/fs.h
|
|
+++ b/include/linux/fs.h
|
|
@@ -249,6 +249,12 @@ struct iattr {
|
|
*/
|
|
#include <linux/quota.h>
|
|
|
|
+/*
|
|
+ * Maximum number of layers of fs stack. Needs to be limited to
|
|
+ * prevent kernel stack overflow
|
|
+ */
|
|
+#define FILESYSTEM_MAX_STACK_DEPTH 2
|
|
+
|
|
/**
|
|
* enum positive_aop_returns - aop return codes with specific semantics
|
|
*
|
|
@@ -1329,6 +1335,11 @@ struct super_block {
|
|
struct list_lru s_dentry_lru ____cacheline_aligned_in_smp;
|
|
struct list_lru s_inode_lru ____cacheline_aligned_in_smp;
|
|
struct rcu_head rcu;
|
|
+
|
|
+ /*
|
|
+ * Indicates how deep in a filesystem stack this SB is
|
|
+ */
|
|
+ int s_stack_depth;
|
|
};
|
|
|
|
extern struct timespec current_fs_time(struct super_block *sb);
|
|
@@ -1585,6 +1596,7 @@ struct inode_operations {
|
|
umode_t create_mode, int *opened);
|
|
int (*tmpfile) (struct inode *, struct dentry *, umode_t);
|
|
int (*set_acl)(struct inode *, struct posix_acl *, int);
|
|
+ int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
|
|
} ____cacheline_aligned;
|
|
|
|
ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
|
|
@@ -2079,6 +2091,7 @@ extern struct file *file_open_name(struc
|
|
extern struct file *filp_open(const char *, int, umode_t);
|
|
extern struct file *file_open_root(struct dentry *, struct vfsmount *,
|
|
const char *, int);
|
|
+extern int vfs_open(const struct path *, struct file *, const struct cred *);
|
|
extern struct file * dentry_open(const struct path *, int, const struct cred *);
|
|
extern int filp_close(struct file *, fl_owner_t id);
|
|
|
|
@@ -2292,6 +2305,7 @@ extern sector_t bmap(struct inode *, sec
|
|
#endif
|
|
extern int notify_change(struct dentry *, struct iattr *, struct inode **);
|
|
extern int inode_permission(struct inode *, int);
|
|
+extern int __inode_permission(struct inode *, int);
|
|
extern int generic_permission(struct inode *, int);
|
|
|
|
static inline bool execute_ok(struct inode *inode)
|
|
@@ -2500,6 +2514,9 @@ extern ssize_t generic_file_splice_write
|
|
struct file *, loff_t *, size_t, unsigned int);
|
|
extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe,
|
|
struct file *out, loff_t *, size_t len, unsigned int flags);
|
|
+extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
|
|
+ loff_t *opos, size_t len, unsigned int flags);
|
|
+
|
|
|
|
extern void
|
|
file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
|
|
--- a/include/linux/mount.h
|
|
+++ b/include/linux/mount.h
|
|
@@ -74,6 +74,9 @@ extern void mnt_pin(struct vfsmount *mnt
|
|
extern void mnt_unpin(struct vfsmount *mnt);
|
|
extern int __mnt_is_readonly(struct vfsmount *mnt);
|
|
|
|
+struct path;
|
|
+extern struct vfsmount *clone_private_mount(struct path *path);
|
|
+
|
|
struct file_system_type;
|
|
extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
|
|
int flags, const char *name,
|
|
|