1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2015, Primary Data, Inc. All rights reserved.
4 *
5 * Tao Peng <bergwolf@primarydata.com>
6 */
7#include <linux/dcache.h>
8#include <linux/exportfs.h>
9#include <linux/nfs.h>
10#include <linux/nfs_fs.h>
11
12#include "internal.h"
13#include "nfstrace.h"
14
15#define NFSDBG_FACILITY NFSDBG_VFS
16
17enum {
18 FILEID_HIGH_OFF = 0, /* inode fileid high */
19 FILEID_LOW_OFF, /* inode fileid low */
20 FILE_I_TYPE_OFF, /* inode type */
21 EMBED_FH_OFF /* embeded server fh */
22};
23
24
25static struct nfs_fh *nfs_exp_embedfh(__u32 *p)
26{
27 return (struct nfs_fh *)(p + EMBED_FH_OFF);
28}
29
30/*
31 * Let's break subtree checking for now... otherwise we'll have to embed parent fh
32 * but there might not be enough space.
33 */
34static int
35nfs_encode_fh(struct inode *inode, __u32 *p, int *max_len, struct inode *parent)
36{
37 struct nfs_fh *server_fh = NFS_FH(inode);
38 struct nfs_fh *clnt_fh = nfs_exp_embedfh(p);
39 size_t fh_size = offsetof(struct nfs_fh, data) + server_fh->size;
40 int len = EMBED_FH_OFF + XDR_QUADLEN(fh_size);
41
42 dprintk("%s: max fh len %d inode %p parent %p",
43 __func__, *max_len, inode, parent);
44
45 if (*max_len < len) {
46 dprintk("%s: fh len %d too small, required %d\n",
47 __func__, *max_len, len);
48 *max_len = len;
49 return FILEID_INVALID;
50 }
51
52 p[FILEID_HIGH_OFF] = NFS_FILEID(inode) >> 32;
53 p[FILEID_LOW_OFF] = NFS_FILEID(inode);
54 p[FILE_I_TYPE_OFF] = inode->i_mode & S_IFMT;
55 p[len - 1] = 0; /* Padding */
56 nfs_copy_fh(target: clnt_fh, source: server_fh);
57 *max_len = len;
58 dprintk("%s: result fh fileid %llu mode %u size %d\n",
59 __func__, NFS_FILEID(inode), inode->i_mode, *max_len);
60 return *max_len;
61}
62
63static struct dentry *
64nfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
65 int fh_len, int fh_type)
66{
67 struct nfs_fattr *fattr = NULL;
68 struct nfs_fh *server_fh = nfs_exp_embedfh(p: fid->raw);
69 size_t fh_size = offsetof(struct nfs_fh, data);
70 const struct nfs_rpc_ops *rpc_ops;
71 struct dentry *dentry;
72 struct inode *inode;
73 int len = EMBED_FH_OFF;
74 u32 *p = fid->raw;
75 int ret;
76
77 /* Initial check of bounds */
78 if (fh_len < len + XDR_QUADLEN(fh_size) ||
79 fh_len > XDR_QUADLEN(NFS_MAXFHSIZE))
80 return NULL;
81 /* Calculate embedded filehandle size */
82 fh_size += server_fh->size;
83 len += XDR_QUADLEN(fh_size);
84 /* NULL translates to ESTALE */
85 if (fh_len < len || fh_type != len)
86 return NULL;
87
88 fattr = nfs_alloc_fattr_with_label(server: NFS_SB(s: sb));
89 if (fattr == NULL) {
90 dentry = ERR_PTR(error: -ENOMEM);
91 goto out;
92 }
93
94 fattr->fileid = ((u64)p[FILEID_HIGH_OFF] << 32) + p[FILEID_LOW_OFF];
95 fattr->mode = p[FILE_I_TYPE_OFF];
96 fattr->valid |= NFS_ATTR_FATTR_FILEID | NFS_ATTR_FATTR_TYPE;
97
98 dprintk("%s: fileid %llu mode %d\n", __func__, fattr->fileid, fattr->mode);
99
100 inode = nfs_ilookup(sb, fattr, server_fh);
101 if (inode)
102 goto out_found;
103
104 rpc_ops = NFS_SB(s: sb)->nfs_client->rpc_ops;
105 ret = rpc_ops->getattr(NFS_SB(s: sb), server_fh, fattr, NULL);
106 if (ret) {
107 dprintk("%s: getattr failed %d\n", __func__, ret);
108 trace_nfs_fh_to_dentry(sb, fh: server_fh, fileid: fattr->fileid, error: ret);
109 dentry = ERR_PTR(error: ret);
110 goto out_free_fattr;
111 }
112
113 inode = nfs_fhget(sb, server_fh, fattr);
114
115out_found:
116 dentry = d_obtain_alias(inode);
117out_free_fattr:
118 nfs_free_fattr(fattr);
119out:
120 return dentry;
121}
122
123static struct dentry *
124nfs_get_parent(struct dentry *dentry)
125{
126 int ret;
127 struct inode *inode = d_inode(dentry), *pinode;
128 struct super_block *sb = inode->i_sb;
129 struct nfs_server *server = NFS_SB(s: sb);
130 struct nfs_fattr *fattr = NULL;
131 struct dentry *parent;
132 struct nfs_rpc_ops const *ops = server->nfs_client->rpc_ops;
133 struct nfs_fh fh;
134
135 if (!ops->lookupp)
136 return ERR_PTR(error: -EACCES);
137
138 fattr = nfs_alloc_fattr_with_label(server);
139 if (fattr == NULL)
140 return ERR_PTR(error: -ENOMEM);
141
142 ret = ops->lookupp(inode, &fh, fattr);
143 if (ret) {
144 parent = ERR_PTR(error: ret);
145 goto out;
146 }
147
148 pinode = nfs_fhget(sb, &fh, fattr);
149 parent = d_obtain_alias(pinode);
150out:
151 nfs_free_fattr(fattr);
152 return parent;
153}
154
155const struct export_operations nfs_export_ops = {
156 .encode_fh = nfs_encode_fh,
157 .fh_to_dentry = nfs_fh_to_dentry,
158 .get_parent = nfs_get_parent,
159 .flags = EXPORT_OP_NOWCC |
160 EXPORT_OP_NOSUBTREECHK |
161 EXPORT_OP_CLOSE_BEFORE_UNLINK |
162 EXPORT_OP_REMOTE_FS |
163 EXPORT_OP_NOATOMIC_ATTR |
164 EXPORT_OP_FLUSH_ON_CLOSE |
165 EXPORT_OP_NOLOCKS,
166};
167

source code of linux/fs/nfs/export.c