forked from Minki/linux
d2912cb15b
Based on 2 normalized pattern(s): 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 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 # extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 4122 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Enrico Weigelt <info@metux.net> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
849 lines
22 KiB
C
849 lines
22 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Overlayfs NFS export support.
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*
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* Amir Goldstein <amir73il@gmail.com>
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*
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* Copyright (C) 2017-2018 CTERA Networks. All Rights Reserved.
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*/
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#include <linux/fs.h>
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#include <linux/cred.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/xattr.h>
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#include <linux/exportfs.h>
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#include <linux/ratelimit.h>
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#include "overlayfs.h"
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static int ovl_encode_maybe_copy_up(struct dentry *dentry)
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{
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int err;
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if (ovl_dentry_upper(dentry))
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return 0;
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err = ovl_want_write(dentry);
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if (!err) {
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err = ovl_copy_up(dentry);
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ovl_drop_write(dentry);
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}
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if (err) {
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pr_warn_ratelimited("overlayfs: failed to copy up on encode (%pd2, err=%i)\n",
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dentry, err);
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}
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return err;
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}
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/*
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* Before encoding a non-upper directory file handle from real layer N, we need
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* to check if it will be possible to reconnect an overlay dentry from the real
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* lower decoded dentry. This is done by following the overlay ancestry up to a
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* "layer N connected" ancestor and verifying that all parents along the way are
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* "layer N connectable". If an ancestor that is NOT "layer N connectable" is
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* found, we need to copy up an ancestor, which is "layer N connectable", thus
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* making that ancestor "layer N connected". For example:
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*
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* layer 1: /a
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* layer 2: /a/b/c
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*
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* The overlay dentry /a is NOT "layer 2 connectable", because if dir /a is
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* copied up and renamed, upper dir /a will be indexed by lower dir /a from
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* layer 1. The dir /a from layer 2 will never be indexed, so the algorithm (*)
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* in ovl_lookup_real_ancestor() will not be able to lookup a connected overlay
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* dentry from the connected lower dentry /a/b/c.
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*
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* To avoid this problem on decode time, we need to copy up an ancestor of
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* /a/b/c, which is "layer 2 connectable", on encode time. That ancestor is
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* /a/b. After copy up (and index) of /a/b, it will become "layer 2 connected"
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* and when the time comes to decode the file handle from lower dentry /a/b/c,
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* ovl_lookup_real_ancestor() will find the indexed ancestor /a/b and decoding
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* a connected overlay dentry will be accomplished.
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*
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* (*) the algorithm in ovl_lookup_real_ancestor() can be improved to lookup an
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* entry /a in the lower layers above layer N and find the indexed dir /a from
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* layer 1. If that improvement is made, then the check for "layer N connected"
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* will need to verify there are no redirects in lower layers above N. In the
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* example above, /a will be "layer 2 connectable". However, if layer 2 dir /a
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* is a target of a layer 1 redirect, then /a will NOT be "layer 2 connectable":
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*
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* layer 1: /A (redirect = /a)
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* layer 2: /a/b/c
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*/
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/* Return the lowest layer for encoding a connectable file handle */
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static int ovl_connectable_layer(struct dentry *dentry)
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{
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struct ovl_entry *oe = OVL_E(dentry);
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/* We can get overlay root from root of any layer */
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if (dentry == dentry->d_sb->s_root)
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return oe->numlower;
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/*
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* If it's an unindexed merge dir, then it's not connectable with any
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* lower layer
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*/
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if (ovl_dentry_upper(dentry) &&
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!ovl_test_flag(OVL_INDEX, d_inode(dentry)))
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return 0;
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/* We can get upper/overlay path from indexed/lower dentry */
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return oe->lowerstack[0].layer->idx;
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}
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/*
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* @dentry is "connected" if all ancestors up to root or a "connected" ancestor
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* have the same uppermost lower layer as the origin's layer. We may need to
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* copy up a "connectable" ancestor to make it "connected". A "connected" dentry
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* cannot become non "connected", so cache positive result in dentry flags.
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*
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* Return the connected origin layer or < 0 on error.
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*/
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static int ovl_connect_layer(struct dentry *dentry)
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{
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struct dentry *next, *parent = NULL;
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int origin_layer;
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int err = 0;
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if (WARN_ON(dentry == dentry->d_sb->s_root) ||
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WARN_ON(!ovl_dentry_lower(dentry)))
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return -EIO;
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origin_layer = OVL_E(dentry)->lowerstack[0].layer->idx;
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if (ovl_dentry_test_flag(OVL_E_CONNECTED, dentry))
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return origin_layer;
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/* Find the topmost origin layer connectable ancestor of @dentry */
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next = dget(dentry);
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for (;;) {
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parent = dget_parent(next);
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if (WARN_ON(parent == next)) {
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err = -EIO;
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break;
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}
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/*
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* If @parent is not origin layer connectable, then copy up
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* @next which is origin layer connectable and we are done.
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*/
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if (ovl_connectable_layer(parent) < origin_layer) {
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err = ovl_encode_maybe_copy_up(next);
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break;
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}
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/* If @parent is connected or indexed we are done */
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if (ovl_dentry_test_flag(OVL_E_CONNECTED, parent) ||
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ovl_test_flag(OVL_INDEX, d_inode(parent)))
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break;
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dput(next);
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next = parent;
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}
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dput(parent);
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dput(next);
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if (!err)
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ovl_dentry_set_flag(OVL_E_CONNECTED, dentry);
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return err ?: origin_layer;
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}
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/*
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* We only need to encode origin if there is a chance that the same object was
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* encoded pre copy up and then we need to stay consistent with the same
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* encoding also after copy up. If non-pure upper is not indexed, then it was
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* copied up before NFS export was enabled. In that case we don't need to worry
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* about staying consistent with pre copy up encoding and we encode an upper
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* file handle. Overlay root dentry is a private case of non-indexed upper.
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*
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* The following table summarizes the different file handle encodings used for
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* different overlay object types:
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*
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* Object type | Encoding
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* --------------------------------
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* Pure upper | U
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* Non-indexed upper | U
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* Indexed upper | L (*)
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* Non-upper | L (*)
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*
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* U = upper file handle
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* L = lower file handle
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*
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* (*) Connecting an overlay dir from real lower dentry is not always
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* possible when there are redirects in lower layers and non-indexed merge dirs.
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* To mitigate those case, we may copy up the lower dir ancestor before encode
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* a lower dir file handle.
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*
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* Return 0 for upper file handle, > 0 for lower file handle or < 0 on error.
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*/
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static int ovl_check_encode_origin(struct dentry *dentry)
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{
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
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/* Upper file handle for pure upper */
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if (!ovl_dentry_lower(dentry))
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return 0;
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/*
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* Upper file handle for non-indexed upper.
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*
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* Root is never indexed, so if there's an upper layer, encode upper for
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* root.
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*/
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if (ovl_dentry_upper(dentry) &&
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!ovl_test_flag(OVL_INDEX, d_inode(dentry)))
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return 0;
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/*
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* Decoding a merge dir, whose origin's ancestor is under a redirected
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* lower dir or under a non-indexed upper is not always possible.
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* ovl_connect_layer() will try to make origin's layer "connected" by
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* copying up a "connectable" ancestor.
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*/
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if (d_is_dir(dentry) && ofs->upper_mnt)
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return ovl_connect_layer(dentry);
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/* Lower file handle for indexed and non-upper dir/non-dir */
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return 1;
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}
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static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen)
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{
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struct ovl_fh *fh = NULL;
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int err, enc_lower;
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/*
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* Check if we should encode a lower or upper file handle and maybe
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* copy up an ancestor to make lower file handle connectable.
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*/
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err = enc_lower = ovl_check_encode_origin(dentry);
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if (enc_lower < 0)
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goto fail;
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/* Encode an upper or lower file handle */
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fh = ovl_encode_real_fh(enc_lower ? ovl_dentry_lower(dentry) :
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ovl_dentry_upper(dentry), !enc_lower);
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err = PTR_ERR(fh);
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if (IS_ERR(fh))
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goto fail;
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err = -EOVERFLOW;
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if (fh->len > buflen)
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goto fail;
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memcpy(buf, (char *)fh, fh->len);
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err = fh->len;
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out:
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kfree(fh);
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return err;
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fail:
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pr_warn_ratelimited("overlayfs: failed to encode file handle (%pd2, err=%i, buflen=%d, len=%d, type=%d)\n",
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dentry, err, buflen, fh ? (int)fh->len : 0,
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fh ? fh->type : 0);
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goto out;
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}
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static int ovl_dentry_to_fh(struct dentry *dentry, u32 *fid, int *max_len)
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{
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int res, len = *max_len << 2;
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res = ovl_d_to_fh(dentry, (char *)fid, len);
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if (res <= 0)
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return FILEID_INVALID;
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len = res;
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/* Round up to dwords */
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*max_len = (len + 3) >> 2;
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return OVL_FILEID;
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}
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static int ovl_encode_fh(struct inode *inode, u32 *fid, int *max_len,
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struct inode *parent)
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{
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struct dentry *dentry;
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int type;
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/* TODO: encode connectable file handles */
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if (parent)
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return FILEID_INVALID;
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dentry = d_find_any_alias(inode);
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if (WARN_ON(!dentry))
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return FILEID_INVALID;
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type = ovl_dentry_to_fh(dentry, fid, max_len);
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dput(dentry);
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return type;
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}
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/*
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* Find or instantiate an overlay dentry from real dentries and index.
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*/
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static struct dentry *ovl_obtain_alias(struct super_block *sb,
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struct dentry *upper_alias,
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struct ovl_path *lowerpath,
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struct dentry *index)
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{
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struct dentry *lower = lowerpath ? lowerpath->dentry : NULL;
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struct dentry *upper = upper_alias ?: index;
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struct dentry *dentry;
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struct inode *inode;
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struct ovl_entry *oe;
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struct ovl_inode_params oip = {
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.lowerpath = lowerpath,
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.index = index,
|
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.numlower = !!lower
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};
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|
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/* We get overlay directory dentries with ovl_lookup_real() */
|
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if (d_is_dir(upper ?: lower))
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return ERR_PTR(-EIO);
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|
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oip.upperdentry = dget(upper);
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inode = ovl_get_inode(sb, &oip);
|
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if (IS_ERR(inode)) {
|
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dput(upper);
|
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return ERR_CAST(inode);
|
|
}
|
|
|
|
if (upper)
|
|
ovl_set_flag(OVL_UPPERDATA, inode);
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|
|
dentry = d_find_any_alias(inode);
|
|
if (!dentry) {
|
|
dentry = d_alloc_anon(inode->i_sb);
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if (!dentry)
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goto nomem;
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|
oe = ovl_alloc_entry(lower ? 1 : 0);
|
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if (!oe)
|
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goto nomem;
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|
|
if (lower) {
|
|
oe->lowerstack->dentry = dget(lower);
|
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oe->lowerstack->layer = lowerpath->layer;
|
|
}
|
|
dentry->d_fsdata = oe;
|
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if (upper_alias)
|
|
ovl_dentry_set_upper_alias(dentry);
|
|
}
|
|
|
|
return d_instantiate_anon(dentry, inode);
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|
|
nomem:
|
|
iput(inode);
|
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dput(dentry);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
/* Get the upper or lower dentry in stach whose on layer @idx */
|
|
static struct dentry *ovl_dentry_real_at(struct dentry *dentry, int idx)
|
|
{
|
|
struct ovl_entry *oe = dentry->d_fsdata;
|
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int i;
|
|
|
|
if (!idx)
|
|
return ovl_dentry_upper(dentry);
|
|
|
|
for (i = 0; i < oe->numlower; i++) {
|
|
if (oe->lowerstack[i].layer->idx == idx)
|
|
return oe->lowerstack[i].dentry;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Lookup a child overlay dentry to get a connected overlay dentry whose real
|
|
* dentry is @real. If @real is on upper layer, we lookup a child overlay
|
|
* dentry with the same name as the real dentry. Otherwise, we need to consult
|
|
* index for lookup.
|
|
*/
|
|
static struct dentry *ovl_lookup_real_one(struct dentry *connected,
|
|
struct dentry *real,
|
|
struct ovl_layer *layer)
|
|
{
|
|
struct inode *dir = d_inode(connected);
|
|
struct dentry *this, *parent = NULL;
|
|
struct name_snapshot name;
|
|
int err;
|
|
|
|
/*
|
|
* Lookup child overlay dentry by real name. The dir mutex protects us
|
|
* from racing with overlay rename. If the overlay dentry that is above
|
|
* real has already been moved to a parent that is not under the
|
|
* connected overlay dir, we return -ECHILD and restart the lookup of
|
|
* connected real path from the top.
|
|
*/
|
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inode_lock_nested(dir, I_MUTEX_PARENT);
|
|
err = -ECHILD;
|
|
parent = dget_parent(real);
|
|
if (ovl_dentry_real_at(connected, layer->idx) != parent)
|
|
goto fail;
|
|
|
|
/*
|
|
* We also need to take a snapshot of real dentry name to protect us
|
|
* from racing with underlying layer rename. In this case, we don't
|
|
* care about returning ESTALE, only from dereferencing a free name
|
|
* pointer because we hold no lock on the real dentry.
|
|
*/
|
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take_dentry_name_snapshot(&name, real);
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this = lookup_one_len(name.name.name, connected, name.name.len);
|
|
err = PTR_ERR(this);
|
|
if (IS_ERR(this)) {
|
|
goto fail;
|
|
} else if (!this || !this->d_inode) {
|
|
dput(this);
|
|
err = -ENOENT;
|
|
goto fail;
|
|
} else if (ovl_dentry_real_at(this, layer->idx) != real) {
|
|
dput(this);
|
|
err = -ESTALE;
|
|
goto fail;
|
|
}
|
|
|
|
out:
|
|
release_dentry_name_snapshot(&name);
|
|
dput(parent);
|
|
inode_unlock(dir);
|
|
return this;
|
|
|
|
fail:
|
|
pr_warn_ratelimited("overlayfs: failed to lookup one by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
|
|
real, layer->idx, connected, err);
|
|
this = ERR_PTR(err);
|
|
goto out;
|
|
}
|
|
|
|
static struct dentry *ovl_lookup_real(struct super_block *sb,
|
|
struct dentry *real,
|
|
struct ovl_layer *layer);
|
|
|
|
/*
|
|
* Lookup an indexed or hashed overlay dentry by real inode.
|
|
*/
|
|
static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
|
|
struct dentry *real,
|
|
struct ovl_layer *layer)
|
|
{
|
|
struct ovl_fs *ofs = sb->s_fs_info;
|
|
struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
|
|
struct dentry *index = NULL;
|
|
struct dentry *this = NULL;
|
|
struct inode *inode;
|
|
|
|
/*
|
|
* Decoding upper dir from index is expensive, so first try to lookup
|
|
* overlay dentry in inode/dcache.
|
|
*/
|
|
inode = ovl_lookup_inode(sb, real, !layer->idx);
|
|
if (IS_ERR(inode))
|
|
return ERR_CAST(inode);
|
|
if (inode) {
|
|
this = d_find_any_alias(inode);
|
|
iput(inode);
|
|
}
|
|
|
|
/*
|
|
* For decoded lower dir file handle, lookup index by origin to check
|
|
* if lower dir was copied up and and/or removed.
|
|
*/
|
|
if (!this && layer->idx && ofs->indexdir && !WARN_ON(!d_is_dir(real))) {
|
|
index = ovl_lookup_index(ofs, NULL, real, false);
|
|
if (IS_ERR(index))
|
|
return index;
|
|
}
|
|
|
|
/* Get connected upper overlay dir from index */
|
|
if (index) {
|
|
struct dentry *upper = ovl_index_upper(ofs, index);
|
|
|
|
dput(index);
|
|
if (IS_ERR_OR_NULL(upper))
|
|
return upper;
|
|
|
|
/*
|
|
* ovl_lookup_real() in lower layer may call recursively once to
|
|
* ovl_lookup_real() in upper layer. The first level call walks
|
|
* back lower parents to the topmost indexed parent. The second
|
|
* recursive call walks back from indexed upper to the topmost
|
|
* connected/hashed upper parent (or up to root).
|
|
*/
|
|
this = ovl_lookup_real(sb, upper, &upper_layer);
|
|
dput(upper);
|
|
}
|
|
|
|
if (IS_ERR_OR_NULL(this))
|
|
return this;
|
|
|
|
if (WARN_ON(ovl_dentry_real_at(this, layer->idx) != real)) {
|
|
dput(this);
|
|
this = ERR_PTR(-EIO);
|
|
}
|
|
|
|
return this;
|
|
}
|
|
|
|
/*
|
|
* Lookup an indexed or hashed overlay dentry, whose real dentry is an
|
|
* ancestor of @real.
|
|
*/
|
|
static struct dentry *ovl_lookup_real_ancestor(struct super_block *sb,
|
|
struct dentry *real,
|
|
struct ovl_layer *layer)
|
|
{
|
|
struct dentry *next, *parent = NULL;
|
|
struct dentry *ancestor = ERR_PTR(-EIO);
|
|
|
|
if (real == layer->mnt->mnt_root)
|
|
return dget(sb->s_root);
|
|
|
|
/* Find the topmost indexed or hashed ancestor */
|
|
next = dget(real);
|
|
for (;;) {
|
|
parent = dget_parent(next);
|
|
|
|
/*
|
|
* Lookup a matching overlay dentry in inode/dentry
|
|
* cache or in index by real inode.
|
|
*/
|
|
ancestor = ovl_lookup_real_inode(sb, next, layer);
|
|
if (ancestor)
|
|
break;
|
|
|
|
if (parent == layer->mnt->mnt_root) {
|
|
ancestor = dget(sb->s_root);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If @real has been moved out of the layer root directory,
|
|
* we will eventully hit the real fs root. This cannot happen
|
|
* by legit overlay rename, so we return error in that case.
|
|
*/
|
|
if (parent == next) {
|
|
ancestor = ERR_PTR(-EXDEV);
|
|
break;
|
|
}
|
|
|
|
dput(next);
|
|
next = parent;
|
|
}
|
|
|
|
dput(parent);
|
|
dput(next);
|
|
|
|
return ancestor;
|
|
}
|
|
|
|
/*
|
|
* Lookup a connected overlay dentry whose real dentry is @real.
|
|
* If @real is on upper layer, we lookup a child overlay dentry with the same
|
|
* path the real dentry. Otherwise, we need to consult index for lookup.
|
|
*/
|
|
static struct dentry *ovl_lookup_real(struct super_block *sb,
|
|
struct dentry *real,
|
|
struct ovl_layer *layer)
|
|
{
|
|
struct dentry *connected;
|
|
int err = 0;
|
|
|
|
connected = ovl_lookup_real_ancestor(sb, real, layer);
|
|
if (IS_ERR(connected))
|
|
return connected;
|
|
|
|
while (!err) {
|
|
struct dentry *next, *this;
|
|
struct dentry *parent = NULL;
|
|
struct dentry *real_connected = ovl_dentry_real_at(connected,
|
|
layer->idx);
|
|
|
|
if (real_connected == real)
|
|
break;
|
|
|
|
/* Find the topmost dentry not yet connected */
|
|
next = dget(real);
|
|
for (;;) {
|
|
parent = dget_parent(next);
|
|
|
|
if (parent == real_connected)
|
|
break;
|
|
|
|
/*
|
|
* If real has been moved out of 'real_connected',
|
|
* we will not find 'real_connected' and hit the layer
|
|
* root. In that case, we need to restart connecting.
|
|
* This game can go on forever in the worst case. We
|
|
* may want to consider taking s_vfs_rename_mutex if
|
|
* this happens more than once.
|
|
*/
|
|
if (parent == layer->mnt->mnt_root) {
|
|
dput(connected);
|
|
connected = dget(sb->s_root);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If real file has been moved out of the layer root
|
|
* directory, we will eventully hit the real fs root.
|
|
* This cannot happen by legit overlay rename, so we
|
|
* return error in that case.
|
|
*/
|
|
if (parent == next) {
|
|
err = -EXDEV;
|
|
break;
|
|
}
|
|
|
|
dput(next);
|
|
next = parent;
|
|
}
|
|
|
|
if (!err) {
|
|
this = ovl_lookup_real_one(connected, next, layer);
|
|
if (IS_ERR(this))
|
|
err = PTR_ERR(this);
|
|
|
|
/*
|
|
* Lookup of child in overlay can fail when racing with
|
|
* overlay rename of child away from 'connected' parent.
|
|
* In this case, we need to restart the lookup from the
|
|
* top, because we cannot trust that 'real_connected' is
|
|
* still an ancestor of 'real'. There is a good chance
|
|
* that the renamed overlay ancestor is now in cache, so
|
|
* ovl_lookup_real_ancestor() will find it and we can
|
|
* continue to connect exactly from where lookup failed.
|
|
*/
|
|
if (err == -ECHILD) {
|
|
this = ovl_lookup_real_ancestor(sb, real,
|
|
layer);
|
|
err = PTR_ERR_OR_ZERO(this);
|
|
}
|
|
if (!err) {
|
|
dput(connected);
|
|
connected = this;
|
|
}
|
|
}
|
|
|
|
dput(parent);
|
|
dput(next);
|
|
}
|
|
|
|
if (err)
|
|
goto fail;
|
|
|
|
return connected;
|
|
|
|
fail:
|
|
pr_warn_ratelimited("overlayfs: failed to lookup by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
|
|
real, layer->idx, connected, err);
|
|
dput(connected);
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
/*
|
|
* Get an overlay dentry from upper/lower real dentries and index.
|
|
*/
|
|
static struct dentry *ovl_get_dentry(struct super_block *sb,
|
|
struct dentry *upper,
|
|
struct ovl_path *lowerpath,
|
|
struct dentry *index)
|
|
{
|
|
struct ovl_fs *ofs = sb->s_fs_info;
|
|
struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
|
|
struct ovl_layer *layer = upper ? &upper_layer : lowerpath->layer;
|
|
struct dentry *real = upper ?: (index ?: lowerpath->dentry);
|
|
|
|
/*
|
|
* Obtain a disconnected overlay dentry from a non-dir real dentry
|
|
* and index.
|
|
*/
|
|
if (!d_is_dir(real))
|
|
return ovl_obtain_alias(sb, upper, lowerpath, index);
|
|
|
|
/* Removed empty directory? */
|
|
if ((real->d_flags & DCACHE_DISCONNECTED) || d_unhashed(real))
|
|
return ERR_PTR(-ENOENT);
|
|
|
|
/*
|
|
* If real dentry is connected and hashed, get a connected overlay
|
|
* dentry whose real dentry is @real.
|
|
*/
|
|
return ovl_lookup_real(sb, real, layer);
|
|
}
|
|
|
|
static struct dentry *ovl_upper_fh_to_d(struct super_block *sb,
|
|
struct ovl_fh *fh)
|
|
{
|
|
struct ovl_fs *ofs = sb->s_fs_info;
|
|
struct dentry *dentry;
|
|
struct dentry *upper;
|
|
|
|
if (!ofs->upper_mnt)
|
|
return ERR_PTR(-EACCES);
|
|
|
|
upper = ovl_decode_real_fh(fh, ofs->upper_mnt, true);
|
|
if (IS_ERR_OR_NULL(upper))
|
|
return upper;
|
|
|
|
dentry = ovl_get_dentry(sb, upper, NULL, NULL);
|
|
dput(upper);
|
|
|
|
return dentry;
|
|
}
|
|
|
|
static struct dentry *ovl_lower_fh_to_d(struct super_block *sb,
|
|
struct ovl_fh *fh)
|
|
{
|
|
struct ovl_fs *ofs = sb->s_fs_info;
|
|
struct ovl_path origin = { };
|
|
struct ovl_path *stack = &origin;
|
|
struct dentry *dentry = NULL;
|
|
struct dentry *index = NULL;
|
|
struct inode *inode;
|
|
int err;
|
|
|
|
/* First lookup overlay inode in inode cache by origin fh */
|
|
err = ovl_check_origin_fh(ofs, fh, false, NULL, &stack);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
if (!d_is_dir(origin.dentry) ||
|
|
!(origin.dentry->d_flags & DCACHE_DISCONNECTED)) {
|
|
inode = ovl_lookup_inode(sb, origin.dentry, false);
|
|
err = PTR_ERR(inode);
|
|
if (IS_ERR(inode))
|
|
goto out_err;
|
|
if (inode) {
|
|
dentry = d_find_any_alias(inode);
|
|
iput(inode);
|
|
if (dentry)
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
/* Then lookup indexed upper/whiteout by origin fh */
|
|
if (ofs->indexdir) {
|
|
index = ovl_get_index_fh(ofs, fh);
|
|
err = PTR_ERR(index);
|
|
if (IS_ERR(index)) {
|
|
index = NULL;
|
|
goto out_err;
|
|
}
|
|
}
|
|
|
|
/* Then try to get a connected upper dir by index */
|
|
if (index && d_is_dir(index)) {
|
|
struct dentry *upper = ovl_index_upper(ofs, index);
|
|
|
|
err = PTR_ERR(upper);
|
|
if (IS_ERR_OR_NULL(upper))
|
|
goto out_err;
|
|
|
|
dentry = ovl_get_dentry(sb, upper, NULL, NULL);
|
|
dput(upper);
|
|
goto out;
|
|
}
|
|
|
|
/* Find origin.dentry again with ovl_acceptable() layer check */
|
|
if (d_is_dir(origin.dentry)) {
|
|
dput(origin.dentry);
|
|
origin.dentry = NULL;
|
|
err = ovl_check_origin_fh(ofs, fh, true, NULL, &stack);
|
|
if (err)
|
|
goto out_err;
|
|
}
|
|
if (index) {
|
|
err = ovl_verify_origin(index, origin.dentry, false);
|
|
if (err)
|
|
goto out_err;
|
|
}
|
|
|
|
/* Get a connected non-upper dir or disconnected non-dir */
|
|
dentry = ovl_get_dentry(sb, NULL, &origin, index);
|
|
|
|
out:
|
|
dput(origin.dentry);
|
|
dput(index);
|
|
return dentry;
|
|
|
|
out_err:
|
|
dentry = ERR_PTR(err);
|
|
goto out;
|
|
}
|
|
|
|
static struct dentry *ovl_fh_to_dentry(struct super_block *sb, struct fid *fid,
|
|
int fh_len, int fh_type)
|
|
{
|
|
struct dentry *dentry = NULL;
|
|
struct ovl_fh *fh = (struct ovl_fh *) fid;
|
|
int len = fh_len << 2;
|
|
unsigned int flags = 0;
|
|
int err;
|
|
|
|
err = -EINVAL;
|
|
if (fh_type != OVL_FILEID)
|
|
goto out_err;
|
|
|
|
err = ovl_check_fh_len(fh, len);
|
|
if (err)
|
|
goto out_err;
|
|
|
|
flags = fh->flags;
|
|
dentry = (flags & OVL_FH_FLAG_PATH_UPPER) ?
|
|
ovl_upper_fh_to_d(sb, fh) :
|
|
ovl_lower_fh_to_d(sb, fh);
|
|
err = PTR_ERR(dentry);
|
|
if (IS_ERR(dentry) && err != -ESTALE)
|
|
goto out_err;
|
|
|
|
return dentry;
|
|
|
|
out_err:
|
|
pr_warn_ratelimited("overlayfs: failed to decode file handle (len=%d, type=%d, flags=%x, err=%i)\n",
|
|
len, fh_type, flags, err);
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
static struct dentry *ovl_fh_to_parent(struct super_block *sb, struct fid *fid,
|
|
int fh_len, int fh_type)
|
|
{
|
|
pr_warn_ratelimited("overlayfs: connectable file handles not supported; use 'no_subtree_check' exportfs option.\n");
|
|
return ERR_PTR(-EACCES);
|
|
}
|
|
|
|
static int ovl_get_name(struct dentry *parent, char *name,
|
|
struct dentry *child)
|
|
{
|
|
/*
|
|
* ovl_fh_to_dentry() returns connected dir overlay dentries and
|
|
* ovl_fh_to_parent() is not implemented, so we should not get here.
|
|
*/
|
|
WARN_ON_ONCE(1);
|
|
return -EIO;
|
|
}
|
|
|
|
static struct dentry *ovl_get_parent(struct dentry *dentry)
|
|
{
|
|
/*
|
|
* ovl_fh_to_dentry() returns connected dir overlay dentries, so we
|
|
* should not get here.
|
|
*/
|
|
WARN_ON_ONCE(1);
|
|
return ERR_PTR(-EIO);
|
|
}
|
|
|
|
const struct export_operations ovl_export_operations = {
|
|
.encode_fh = ovl_encode_fh,
|
|
.fh_to_dentry = ovl_fh_to_dentry,
|
|
.fh_to_parent = ovl_fh_to_parent,
|
|
.get_name = ovl_get_name,
|
|
.get_parent = ovl_get_parent,
|
|
};
|