ovl: encode pure upper file handles (8ed5eec9) · Commits · e / devices / android_kernel_xiaomi_nabu

fs/overlayfs/Makefile

+2 −1

Original line number	Original line	Diff line number	Diff line
	@@ -4,4 +4,5 @@

	obj-$(CONFIG_OVERLAY_FS) += overlay.o		obj-$(CONFIG_OVERLAY_FS) += overlay.o

	overlay-objs := super.o namei.o util.o inode.o dir.o readdir.o copy_up.o		overlay-objs := super.o namei.o util.o inode.o dir.o readdir.o copy_up.o \
			export.o

fs/overlayfs/export.c

0 → 100644

+98 −0

Original line number	Original line	Diff line number	Diff line
			/*
			* Overlayfs NFS export support.
			*
			* Amir Goldstein <amir73il@gmail.com>
			*
			* Copyright (C) 2017-2018 CTERA Networks. All Rights Reserved.
			*
			* 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/cred.h>
			#include <linux/mount.h>
			#include <linux/namei.h>
			#include <linux/xattr.h>
			#include <linux/exportfs.h>
			#include <linux/ratelimit.h>
			#include "overlayfs.h"

			static int ovl_d_to_fh(struct dentry dentry, char buf, int buflen)
			{
			struct dentry *upper = ovl_dentry_upper(dentry);
			struct dentry *origin = ovl_dentry_lower(dentry);
			struct ovl_fh *fh = NULL;
			int err;

			/*
			* On overlay with an upper layer, overlay root inode is encoded as
			* an upper file handle, because upper root dir is not indexed.
			*/
			if (dentry == dentry->d_sb->s_root && upper)
			origin = NULL;

			err = -EACCES;
			if (!upper \|\| origin)
			goto fail;

			/* TODO: encode non pure-upper by origin */
			fh = ovl_encode_fh(upper, true);

			err = -EOVERFLOW;
			if (fh->len > buflen)
			goto fail;

			memcpy(buf, (char *)fh, fh->len);
			err = fh->len;

			out:
			kfree(fh);
			return err;

			fail:
			pr_warn_ratelimited("overlayfs: failed to encode file handle (%pd2, err=%i, buflen=%d, len=%d, type=%d)\n",
			dentry, err, buflen, fh ? (int)fh->len : 0,
			fh ? fh->type : 0);
			goto out;
			}

			static int ovl_dentry_to_fh(struct dentry dentry, u32 fid, int *max_len)
			{
			int res, len = *max_len << 2;

			res = ovl_d_to_fh(dentry, (char *)fid, len);
			if (res <= 0)
			return FILEID_INVALID;

			len = res;

			/* Round up to dwords */
			*max_len = (len + 3) >> 2;
			return OVL_FILEID;
			}

			static int ovl_encode_inode_fh(struct inode inode, u32 fid, int *max_len,
			struct inode *parent)
			{
			struct dentry *dentry;
			int type;

			/* TODO: encode connectable file handles */
			if (parent)
			return FILEID_INVALID;

			dentry = d_find_any_alias(inode);
			if (WARN_ON(!dentry))
			return FILEID_INVALID;

			type = ovl_dentry_to_fh(dentry, fid, max_len);

			dput(dentry);
			return type;
			}

			const struct export_operations ovl_export_operations = {
			.encode_fh = ovl_encode_inode_fh,
			};

fs/overlayfs/overlayfs.h

+6 −0

Original line number	Original line	Diff line number	Diff line
	@@ -68,6 +68,9 @@ enum ovl_entry_flag {
	#error Endianness not defined		#error Endianness not defined
	#endif		#endif

			/* The type returned by overlay exportfs ops when encoding an ovl_fh handle */
			#define OVL_FILEID 0xfb

	/* On-disk and in-memeory format for redirect by file handle */		/* On-disk and in-memeory format for redirect by file handle */
	struct ovl_fh {		struct ovl_fh {
	u8 version; /* 0 */		u8 version; /* 0 */
	@@ -351,3 +354,6 @@ int ovl_set_attr(struct dentry upper, struct kstat stat);
	struct ovl_fh ovl_encode_fh(struct dentry real, bool is_upper);		struct ovl_fh ovl_encode_fh(struct dentry real, bool is_upper);
	int ovl_set_origin(struct dentry dentry, struct dentry lower,		int ovl_set_origin(struct dentry dentry, struct dentry lower,
	struct dentry *upper);		struct dentry *upper);

			/* export.c */
			extern const struct export_operations ovl_export_operations;