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