projects / linux-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 8ed5eec9 AG |
1 | /* |
| 2 | * Overlayfs NFS export support. | |
| 3 | * | |
| 4 | * Amir Goldstein <amir73il@gmail.com> | |
| 5 | * | |
| 6 | * Copyright (C) 2017-2018 CTERA Networks. All Rights Reserved. | |
| 7 | * | |
| 8 | * This program is free software; you can redistribute it and/or modify it | |
| 9 | * under the terms of the GNU General Public License version 2 as published by | |
| 10 | * the Free Software Foundation. | |
| 11 | */ | |
| 12 | ||
| 13 | #include <linux/fs.h> | |
| 14 | #include <linux/cred.h> | |
| 15 | #include <linux/mount.h> | |
| 16 | #include <linux/namei.h> | |
| 17 | #include <linux/xattr.h> | |
| 18 | #include <linux/exportfs.h> | |
| 19 | #include <linux/ratelimit.h> | |
| 20 | #include "overlayfs.h" | |
| 21 | ||
| 22 | static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen) | |
| 23 | { | |
| 24 | struct dentry *upper = ovl_dentry_upper(dentry); | |
| 25 | struct dentry *origin = ovl_dentry_lower(dentry); | |
| 26 | struct ovl_fh *fh = NULL; | |
| 27 | int err; | |
| 28 | ||
| 29 | /* | |
| 30 | * On overlay with an upper layer, overlay root inode is encoded as | |
| 31 | * an upper file handle, because upper root dir is not indexed. | |
| 32 | */ | |
| 33 | if (dentry == dentry->d_sb->s_root && upper) | |
| 34 | origin = NULL; | |
| 35 | ||
| 36 | err = -EACCES; | |
| 37 | if (!upper || origin) | |
| 38 | goto fail; | |
| 39 | ||
| 40 | /* TODO: encode non pure-upper by origin */ | |
| 41 | fh = ovl_encode_fh(upper, true); | |
| 42 | ||
| 43 | err = -EOVERFLOW; | |
| 44 | if (fh->len > buflen) | |
| 45 | goto fail; | |
| 46 | ||
| 47 | memcpy(buf, (char *)fh, fh->len); | |
| 48 | err = fh->len; | |
| 49 | ||
| 50 | out: | |
| 51 | kfree(fh); | |
| 52 | return err; | |
| 53 | ||
| 54 | fail: | |
| 55 | pr_warn_ratelimited("overlayfs: failed to encode file handle (%pd2, err=%i, buflen=%d, len=%d, type=%d)\n", | |
| 56 | dentry, err, buflen, fh ? (int)fh->len : 0, | |
| 57 | fh ? fh->type : 0); | |
| 58 | goto out; | |
| 59 | } | |
| 60 | ||
| 61 | static int ovl_dentry_to_fh(struct dentry *dentry, u32 *fid, int *max_len) | |
| 62 | { | |
| 63 | int res, len = *max_len << 2; | |
| 64 | ||
| 65 | res = ovl_d_to_fh(dentry, (char *)fid, len); | |
| 66 | if (res <= 0) | |
| 67 | return FILEID_INVALID; | |
| 68 | ||
| 69 | len = res; | |
| 70 | ||
| 71 | /* Round up to dwords */ | |
| 72 | *max_len = (len + 3) >> 2; | |
| 73 | return OVL_FILEID; | |
| 74 | } | |
| 75 | ||
| 76 | static int ovl_encode_inode_fh(struct inode *inode, u32 *fid, int *max_len, | |
| 77 | struct inode *parent) | |
| 78 | { | |
| 79 | struct dentry *dentry; | |
| 80 | int type; | |
| 81 | ||
| 82 | /* TODO: encode connectable file handles */ | |
| 83 | if (parent) | |
| 84 | return FILEID_INVALID; | |
| 85 | ||
| 86 | dentry = d_find_any_alias(inode); | |
| 87 | if (WARN_ON(!dentry)) | |
| 88 | return FILEID_INVALID; | |
| 89 | ||
| 90 | type = ovl_dentry_to_fh(dentry, fid, max_len); | |
| 91 | ||
| 92 | dput(dentry); | |
| 93 | return type; | |
| 94 | } | |
| 95 | ||
| 96 | const struct export_operations ovl_export_operations = { | |
| 97 | .encode_fh = ovl_encode_inode_fh, | |
| 98 | }; |