forked from luck/tmp_suning_uos_patched
99 lines
2.2 KiB
C
99 lines
2.2 KiB
C
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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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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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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_d_to_fh(struct dentry *dentry, char *buf, int buflen)
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{
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struct dentry *upper = ovl_dentry_upper(dentry);
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struct dentry *origin = ovl_dentry_lower(dentry);
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struct ovl_fh *fh = NULL;
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int err;
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/*
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* On overlay with an upper layer, overlay root inode is encoded as
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* an upper file handle, because upper root dir is not indexed.
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*/
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if (dentry == dentry->d_sb->s_root && upper)
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origin = NULL;
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err = -EACCES;
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if (!upper || origin)
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goto fail;
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/* TODO: encode non pure-upper by origin */
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fh = ovl_encode_fh(upper, true);
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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_inode_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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const struct export_operations ovl_export_operations = {
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.encode_fh = ovl_encode_inode_fh,
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};
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