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54ceac45 DH |
1 | /* getroot.c: get the root dentry for an NFS mount |
2 | * | |
3 | * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. | |
4 | * Written by David Howells (dhowells@redhat.com) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | ||
54ceac45 DH |
12 | #include <linux/module.h> |
13 | #include <linux/init.h> | |
14 | ||
15 | #include <linux/time.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/mm.h> | |
18 | #include <linux/string.h> | |
19 | #include <linux/stat.h> | |
20 | #include <linux/errno.h> | |
21 | #include <linux/unistd.h> | |
22 | #include <linux/sunrpc/clnt.h> | |
23 | #include <linux/sunrpc/stats.h> | |
24 | #include <linux/nfs_fs.h> | |
25 | #include <linux/nfs_mount.h> | |
26 | #include <linux/nfs4_mount.h> | |
27 | #include <linux/lockd/bind.h> | |
54ceac45 DH |
28 | #include <linux/seq_file.h> |
29 | #include <linux/mount.h> | |
30 | #include <linux/nfs_idmap.h> | |
31 | #include <linux/vfs.h> | |
32 | #include <linux/namei.h> | |
6b3286ed | 33 | #include <linux/mnt_namespace.h> |
738a3519 | 34 | #include <linux/security.h> |
54ceac45 DH |
35 | |
36 | #include <asm/system.h> | |
37 | #include <asm/uaccess.h> | |
38 | ||
39 | #include "nfs4_fs.h" | |
40 | #include "delegation.h" | |
41 | #include "internal.h" | |
42 | ||
43 | #define NFSDBG_FACILITY NFSDBG_CLIENT | |
54ceac45 | 44 | |
b09b9417 TM |
45 | /* |
46 | * Set the superblock root dentry. | |
47 | * Note that this function frees the inode in case of error. | |
48 | */ | |
49 | static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *inode) | |
50 | { | |
51 | /* The mntroot acts as the dummy root dentry for this superblock */ | |
52 | if (sb->s_root == NULL) { | |
53 | sb->s_root = d_alloc_root(inode); | |
54 | if (sb->s_root == NULL) { | |
55 | iput(inode); | |
56 | return -ENOMEM; | |
57 | } | |
58 | /* Circumvent igrab(): we know the inode is not being freed */ | |
59 | atomic_inc(&inode->i_count); | |
a10db50a TM |
60 | /* |
61 | * Ensure that this dentry is invisible to d_find_alias(). | |
62 | * Otherwise, it may be spliced into the tree by | |
63 | * d_materialise_unique if a parent directory from the same | |
64 | * filesystem gets mounted at a later time. | |
65 | * This again causes shrink_dcache_for_umount_subtree() to | |
66 | * Oops, since the test for IS_ROOT() will fail. | |
67 | */ | |
68 | spin_lock(&dcache_lock); | |
69 | list_del_init(&sb->s_root->d_alias); | |
70 | spin_unlock(&dcache_lock); | |
b09b9417 TM |
71 | } |
72 | return 0; | |
73 | } | |
74 | ||
54ceac45 DH |
75 | /* |
76 | * get an NFS2/NFS3 root dentry from the root filehandle | |
77 | */ | |
78 | struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh) | |
79 | { | |
80 | struct nfs_server *server = NFS_SB(sb); | |
81 | struct nfs_fsinfo fsinfo; | |
82 | struct nfs_fattr fattr; | |
83 | struct dentry *mntroot; | |
84 | struct inode *inode; | |
85 | int error; | |
86 | ||
54ceac45 DH |
87 | /* get the actual root for this mount */ |
88 | fsinfo.fattr = &fattr; | |
89 | ||
90 | error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo); | |
91 | if (error < 0) { | |
92 | dprintk("nfs_get_root: getattr error = %d\n", -error); | |
93 | return ERR_PTR(error); | |
94 | } | |
95 | ||
96 | inode = nfs_fhget(sb, mntfh, fsinfo.fattr); | |
97 | if (IS_ERR(inode)) { | |
98 | dprintk("nfs_get_root: get root inode failed\n"); | |
e231c2ee | 99 | return ERR_CAST(inode); |
54ceac45 DH |
100 | } |
101 | ||
b09b9417 TM |
102 | error = nfs_superblock_set_dummy_root(sb, inode); |
103 | if (error != 0) | |
104 | return ERR_PTR(error); | |
105 | ||
54ceac45 DH |
106 | /* root dentries normally start off anonymous and get spliced in later |
107 | * if the dentry tree reaches them; however if the dentry already | |
108 | * exists, we'll pick it up at this point and use it as the root | |
109 | */ | |
44003728 CH |
110 | mntroot = d_obtain_alias(inode); |
111 | if (IS_ERR(mntroot)) { | |
54ceac45 | 112 | dprintk("nfs_get_root: get root dentry failed\n"); |
44003728 | 113 | return mntroot; |
54ceac45 DH |
114 | } |
115 | ||
738a3519 DH |
116 | security_d_instantiate(mntroot, inode); |
117 | ||
54ceac45 DH |
118 | if (!mntroot->d_op) |
119 | mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops; | |
120 | ||
121 | return mntroot; | |
122 | } | |
123 | ||
124 | #ifdef CONFIG_NFS_V4 | |
125 | ||
126 | /* | |
127 | * Do a simple pathwalk from the root FH of the server to the nominated target | |
128 | * of the mountpoint | |
129 | * - give error on symlinks | |
130 | * - give error on ".." occurring in the path | |
131 | * - follow traversals | |
132 | */ | |
133 | int nfs4_path_walk(struct nfs_server *server, | |
134 | struct nfs_fh *mntfh, | |
135 | const char *path) | |
136 | { | |
137 | struct nfs_fsinfo fsinfo; | |
138 | struct nfs_fattr fattr; | |
139 | struct nfs_fh lastfh; | |
140 | struct qstr name; | |
141 | int ret; | |
54ceac45 DH |
142 | |
143 | dprintk("--> nfs4_path_walk(,,%s)\n", path); | |
144 | ||
145 | fsinfo.fattr = &fattr; | |
146 | nfs_fattr_init(&fattr); | |
147 | ||
faebf4e2 TM |
148 | /* Eat leading slashes */ |
149 | while (*path == '/') | |
150 | path++; | |
54ceac45 DH |
151 | |
152 | /* Start by getting the root filehandle from the server */ | |
153 | ret = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo); | |
154 | if (ret < 0) { | |
155 | dprintk("nfs4_get_root: getroot error = %d\n", -ret); | |
156 | return ret; | |
157 | } | |
158 | ||
159 | if (fattr.type != NFDIR) { | |
160 | printk(KERN_ERR "nfs4_get_root:" | |
161 | " getroot encountered non-directory\n"); | |
162 | return -ENOTDIR; | |
163 | } | |
164 | ||
faebf4e2 | 165 | /* FIXME: It is quite valid for the server to return a referral here */ |
54ceac45 DH |
166 | if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) { |
167 | printk(KERN_ERR "nfs4_get_root:" | |
168 | " getroot obtained referral\n"); | |
169 | return -EREMOTE; | |
170 | } | |
171 | ||
172 | next_component: | |
173 | dprintk("Next: %s\n", path); | |
174 | ||
175 | /* extract the next bit of the path */ | |
176 | if (!*path) | |
177 | goto path_walk_complete; | |
178 | ||
179 | name.name = path; | |
180 | while (*path && *path != '/') | |
181 | path++; | |
182 | name.len = path - (const char *) name.name; | |
183 | ||
54af3bb5 TM |
184 | if (name.len > NFS4_MAXNAMLEN) |
185 | return -ENAMETOOLONG; | |
186 | ||
54ceac45 DH |
187 | eat_dot_dir: |
188 | while (*path == '/') | |
189 | path++; | |
190 | ||
191 | if (path[0] == '.' && (path[1] == '/' || !path[1])) { | |
192 | path += 2; | |
193 | goto eat_dot_dir; | |
194 | } | |
195 | ||
faebf4e2 | 196 | /* FIXME: Why shouldn't the user be able to use ".." in the path? */ |
54ceac45 DH |
197 | if (path[0] == '.' && path[1] == '.' && (path[2] == '/' || !path[2]) |
198 | ) { | |
199 | printk(KERN_ERR "nfs4_get_root:" | |
200 | " Mount path contains reference to \"..\"\n"); | |
201 | return -EINVAL; | |
202 | } | |
203 | ||
204 | /* lookup the next FH in the sequence */ | |
205 | memcpy(&lastfh, mntfh, sizeof(lastfh)); | |
206 | ||
207 | dprintk("LookupFH: %*.*s [%s]\n", name.len, name.len, name.name, path); | |
208 | ||
209 | ret = server->nfs_client->rpc_ops->lookupfh(server, &lastfh, &name, | |
210 | mntfh, &fattr); | |
211 | if (ret < 0) { | |
212 | dprintk("nfs4_get_root: getroot error = %d\n", -ret); | |
213 | return ret; | |
214 | } | |
215 | ||
216 | if (fattr.type != NFDIR) { | |
217 | printk(KERN_ERR "nfs4_get_root:" | |
218 | " lookupfh encountered non-directory\n"); | |
219 | return -ENOTDIR; | |
220 | } | |
221 | ||
faebf4e2 | 222 | /* FIXME: Referrals are quite valid here too */ |
54ceac45 DH |
223 | if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) { |
224 | printk(KERN_ERR "nfs4_get_root:" | |
225 | " lookupfh obtained referral\n"); | |
226 | return -EREMOTE; | |
227 | } | |
228 | ||
229 | goto next_component; | |
230 | ||
231 | path_walk_complete: | |
232 | memcpy(&server->fsid, &fattr.fsid, sizeof(server->fsid)); | |
233 | dprintk("<-- nfs4_path_walk() = 0\n"); | |
234 | return 0; | |
235 | } | |
236 | ||
237 | /* | |
238 | * get an NFS4 root dentry from the root filehandle | |
239 | */ | |
240 | struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh) | |
241 | { | |
242 | struct nfs_server *server = NFS_SB(sb); | |
243 | struct nfs_fattr fattr; | |
244 | struct dentry *mntroot; | |
245 | struct inode *inode; | |
246 | int error; | |
247 | ||
248 | dprintk("--> nfs4_get_root()\n"); | |
249 | ||
54ceac45 DH |
250 | /* get the info about the server and filesystem */ |
251 | error = nfs4_server_capabilities(server, mntfh); | |
252 | if (error < 0) { | |
253 | dprintk("nfs_get_root: getcaps error = %d\n", | |
254 | -error); | |
255 | return ERR_PTR(error); | |
256 | } | |
257 | ||
258 | /* get the actual root for this mount */ | |
259 | error = server->nfs_client->rpc_ops->getattr(server, mntfh, &fattr); | |
260 | if (error < 0) { | |
261 | dprintk("nfs_get_root: getattr error = %d\n", -error); | |
262 | return ERR_PTR(error); | |
263 | } | |
264 | ||
265 | inode = nfs_fhget(sb, mntfh, &fattr); | |
266 | if (IS_ERR(inode)) { | |
267 | dprintk("nfs_get_root: get root inode failed\n"); | |
e231c2ee | 268 | return ERR_CAST(inode); |
54ceac45 DH |
269 | } |
270 | ||
b09b9417 TM |
271 | error = nfs_superblock_set_dummy_root(sb, inode); |
272 | if (error != 0) | |
273 | return ERR_PTR(error); | |
274 | ||
54ceac45 DH |
275 | /* root dentries normally start off anonymous and get spliced in later |
276 | * if the dentry tree reaches them; however if the dentry already | |
277 | * exists, we'll pick it up at this point and use it as the root | |
278 | */ | |
44003728 CH |
279 | mntroot = d_obtain_alias(inode); |
280 | if (IS_ERR(mntroot)) { | |
54ceac45 | 281 | dprintk("nfs_get_root: get root dentry failed\n"); |
44003728 | 282 | return mntroot; |
54ceac45 DH |
283 | } |
284 | ||
738a3519 DH |
285 | security_d_instantiate(mntroot, inode); |
286 | ||
54ceac45 DH |
287 | if (!mntroot->d_op) |
288 | mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops; | |
289 | ||
290 | dprintk("<-- nfs4_get_root()\n"); | |
291 | return mntroot; | |
292 | } | |
293 | ||
294 | #endif /* CONFIG_NFS_V4 */ |