diff options
| -rw-r--r-- | fs/overlayfs/Makefile | 3 | ||||
| -rw-r--r-- | fs/overlayfs/export.c | 98 | ||||
| -rw-r--r-- | fs/overlayfs/overlayfs.h | 6 |
3 files changed, 106 insertions, 1 deletions
diff --git a/fs/overlayfs/Makefile b/fs/overlayfs/Makefile index 99373bbc1478..30802347a020 100644 --- a/fs/overlayfs/Makefile +++ b/fs/overlayfs/Makefile @@ -4,4 +4,5 @@ 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 diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c new file mode 100644 index 000000000000..67b907ca9cdc --- /dev/null +++ b/fs/overlayfs/export.c @@ -0,0 +1,98 @@ +/* + * 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, +}; diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index 2dddcd257eb3..f2baa2ccaacd 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -68,6 +68,9 @@ enum ovl_entry_flag { #error Endianness not defined #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 */ struct ovl_fh { 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); int ovl_set_origin(struct dentry *dentry, struct dentry *lower, struct dentry *upper); + +/* export.c */ +extern const struct export_operations ovl_export_operations; |