1 /*
2 * linux/fs/nfs/nfs4namespace.c
3 *
4 * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
5 * - Modified by David Howells <dhowells@redhat.com>
6 *
7 * NFSv4 namespace
8 */
9
10 #include <linux/dcache.h>
11 #include <linux/mount.h>
12 #include <linux/namei.h>
13 #include <linux/nfs_fs.h>
14 #include <linux/string.h>
15 #include <linux/sunrpc/clnt.h>
16 #include <linux/vfs.h>
17 #include <linux/inet.h>
18 #include "internal.h"
19 #include "nfs4_fs.h"
20
21 #define NFSDBG_FACILITY NFSDBG_VFS
22
23 /*
24 * Check if fs_root is valid
25 */
26 static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
27 char *buffer, ssize_t buflen)
28 {
29 char *end = buffer + buflen;
30 int n;
31
32 *--end = '\0';
33 buflen--;
34
35 n = pathname->ncomponents;
36 while (--n >= 0) {
37 const struct nfs4_string *component = &pathname->components[n];
38 buflen -= component->len + 1;
39 if (buflen < 0)
40 goto Elong;
41 end -= component->len;
42 memcpy(end, component->data, component->len);
43 *--end = '/';
44 }
45 return end;
46 Elong:
47 return ERR_PTR(-ENAMETOOLONG);
48 }
49
50 /*
51 * Determine the mount path as a string
52 */
53 static char *nfs4_path(const struct vfsmount *mnt_parent,
54 const struct dentry *dentry,
55 char *buffer, ssize_t buflen)
56 {
57 const char *srvpath;
58
59 srvpath = strchr(mnt_parent->mnt_devname, ':');
60 if (srvpath)
61 srvpath++;
62 else
63 srvpath = mnt_parent->mnt_devname;
64
65 return nfs_path(srvpath, mnt_parent->mnt_root, dentry, buffer, buflen);
66 }
67
68 /*
69 * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
70 * believe to be the server path to this dentry
71 */
72 static int nfs4_validate_fspath(const struct vfsmount *mnt_parent,
73 const struct dentry *dentry,
74 const struct nfs4_fs_locations *locations,
75 char *page, char *page2)
76 {
77 const char *path, *fs_path;
78
79 path = nfs4_path(mnt_parent, dentry, page, PAGE_SIZE);
80 if (IS_ERR(path))
81 return PTR_ERR(path);
82
83 fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
84 if (IS_ERR(fs_path))
85 return PTR_ERR(fs_path);
86
87 if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
88 dprintk("%s: path %s does not begin with fsroot %s\n",
89 __FUNCTION__, path, fs_path);
90 return -ENOENT;
91 }
92
93 return 0;
94 }
95
96 /*
97 * Check if the string represents a "valid" IPv4 address
98 */
99 static inline int valid_ipaddr4(const char *buf)
100 {
101 int rc, count, in[4];
102
103 rc = sscanf(buf, "%d.%d.%d.%d", &in[0], &in[1], &in[2], &in[3]);
104 if (rc != 4)
105 return -EINVAL;
106 for (count = 0; count < 4; count++) {
107 if (in[count] > 255)
108 return -EINVAL;
109 }
110 return 0;
111 }
112
113 /**
114 * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
115 * @mnt_parent - mountpoint of parent directory
116 * @dentry - parent directory
117 * @locations - array of NFSv4 server location information
118 *
119 */
120 static struct vfsmount *nfs_follow_referral(const struct vfsmount *mnt_parent,
121 const struct dentry *dentry,
122 const struct nfs4_fs_locations *locations)
123 {
124 struct vfsmount *mnt = ERR_PTR(-ENOENT);
125 struct nfs_clone_mount mountdata = {
126 .sb = mnt_parent->mnt_sb,
127 .dentry = dentry,
128 .authflavor = NFS_SB(mnt_parent->mnt_sb)->client->cl_auth->au_flavor,
129 };
130 char *page = NULL, *page2 = NULL;
131 unsigned int s;
132 int loc, error;
133
134 if (locations == NULL || locations->nlocations <= 0)
135 goto out;
136
137 dprintk("%s: referral at %s/%s\n", __FUNCTION__,
138 dentry->d_parent->d_name.name, dentry->d_name.name);
139
140 page = (char *) __get_free_page(GFP_USER);
141 if (!page)
142 goto out;
143
144 page2 = (char *) __get_free_page(GFP_USER);
145 if (!page2)
146 goto out;
147
148 /* Ensure fs path is a prefix of current dentry path */
149 error = nfs4_validate_fspath(mnt_parent, dentry, locations, page, page2);
150 if (error < 0) {
151 mnt = ERR_PTR(error);
152 goto out;
153 }
154
155 loc = 0;
156 while (loc < locations->nlocations && IS_ERR(mnt)) {
157 const struct nfs4_fs_location *location = &locations->locations[loc];
158 char *mnt_path;
159
160 if (location == NULL || location->nservers <= 0 ||
161 location->rootpath.ncomponents == 0) {
162 loc++;
163 continue;
164 }
165
166 mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
167 if (IS_ERR(mnt_path)) {
168 loc++;
169 continue;
170 }
171 mountdata.mnt_path = mnt_path;
172
173 s = 0;
174 while (s < location->nservers) {
175 struct sockaddr_in addr = {
176 .sin_family = AF_INET,
177 .sin_port = htons(NFS_PORT),
178 };
179
180 if (location->servers[s].len <= 0 ||
181 valid_ipaddr4(location->servers[s].data) < 0) {
182 s++;
183 continue;
184 }
185
186 mountdata.hostname = location->servers[s].data;
187 addr.sin_addr.s_addr = in_aton(mountdata.hostname),
188 mountdata.addr = (struct sockaddr *)&addr;
189 mountdata.addrlen = sizeof(addr);
190
191 snprintf(page, PAGE_SIZE, "%s:%s",
192 mountdata.hostname,
193 mountdata.mnt_path);
194
195 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, &mountdata);
196 if (!IS_ERR(mnt)) {
197 break;
198 }
199 s++;
200 }
201 loc++;
202 }
203
204 out:
205 free_page((unsigned long) page);
206 free_page((unsigned long) page2);
207 dprintk("%s: done\n", __FUNCTION__);
208 return mnt;
209 }
210
211 /*
212 * nfs_do_refmount - handle crossing a referral on server
213 * @dentry - dentry of referral
214 * @nd - nameidata info
215 *
216 */
217 struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry)
218 {
219 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
220 struct dentry *parent;
221 struct nfs4_fs_locations *fs_locations = NULL;
222 struct page *page;
223 int err;
224
225 /* BUG_ON(IS_ROOT(dentry)); */
226 dprintk("%s: enter\n", __FUNCTION__);
227
228 page = alloc_page(GFP_KERNEL);
229 if (page == NULL)
230 goto out;
231
232 fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
233 if (fs_locations == NULL)
234 goto out_free;
235
236 /* Get locations */
237 mnt = ERR_PTR(-ENOENT);
238
239 parent = dget_parent(dentry);
240 dprintk("%s: getting locations for %s/%s\n",
241 __FUNCTION__, parent->d_name.name, dentry->d_name.name);
242
243 err = nfs4_proc_fs_locations(parent->d_inode, &dentry->d_name, fs_locations, page);
244 dput(parent);
245 if (err != 0 ||
246 fs_locations->nlocations <= 0 ||
247 fs_locations->fs_path.ncomponents <= 0)
248 goto out_free;
249
250 mnt = nfs_follow_referral(mnt_parent, dentry, fs_locations);
251 out_free:
252 __free_page(page);
253 kfree(fs_locations);
254 out:
255 dprintk("%s: done\n", __FUNCTION__);
256 return mnt;
257 }
258
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