source: src/linux/universal/linux-4.9/fs/nfs/nfs4namespace.c @ 31662

Last change on this file since 31662 was 31662, checked in by brainslayer, 7 weeks ago

use new squashfs in all kernels

File size: 12.8 KB
Line 
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/nfs_mount.h>
15#include <linux/slab.h>
16#include <linux/string.h>
17#include <linux/sunrpc/clnt.h>
18#include <linux/sunrpc/addr.h>
19#include <linux/vfs.h>
20#include <linux/inet.h>
21#include "internal.h"
22#include "nfs4_fs.h"
23#include "dns_resolve.h"
24
25#define NFSDBG_FACILITY         NFSDBG_VFS
26
27/*
28 * Convert the NFSv4 pathname components into a standard posix path.
29 *
30 * Note that the resulting string will be placed at the end of the buffer
31 */
32static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
33                                         char *buffer, ssize_t buflen)
34{
35        char *end = buffer + buflen;
36        int n;
37
38        *--end = '\0';
39        buflen--;
40
41        n = pathname->ncomponents;
42        while (--n >= 0) {
43                const struct nfs4_string *component = &pathname->components[n];
44                buflen -= component->len + 1;
45                if (buflen < 0)
46                        goto Elong;
47                end -= component->len;
48                memcpy(end, component->data, component->len);
49                *--end = '/';
50        }
51        return end;
52Elong:
53        return ERR_PTR(-ENAMETOOLONG);
54}
55
56/*
57 * return the path component of "<server>:<path>"
58 *  nfspath - the "<server>:<path>" string
59 *  end - one past the last char that could contain "<server>:"
60 * returns NULL on failure
61 */
62static char *nfs_path_component(const char *nfspath, const char *end)
63{
64        char *p;
65
66        if (*nfspath == '[') {
67                /* parse [] escaped IPv6 addrs */
68                p = strchr(nfspath, ']');
69                if (p != NULL && ++p < end && *p == ':')
70                        return p + 1;
71        } else {
72                /* otherwise split on first colon */
73                p = strchr(nfspath, ':');
74                if (p != NULL && p < end)
75                        return p + 1;
76        }
77        return NULL;
78}
79
80/*
81 * Determine the mount path as a string
82 */
83static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
84{
85        char *limit;
86        char *path = nfs_path(&limit, dentry, buffer, buflen,
87                              NFS_PATH_CANONICAL);
88        if (!IS_ERR(path)) {
89                char *path_component = nfs_path_component(path, limit);
90                if (path_component)
91                        return path_component;
92        }
93        return path;
94}
95
96/*
97 * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
98 * believe to be the server path to this dentry
99 */
100static int nfs4_validate_fspath(struct dentry *dentry,
101                                const struct nfs4_fs_locations *locations,
102                                char *page, char *page2)
103{
104        const char *path, *fs_path;
105
106        path = nfs4_path(dentry, page, PAGE_SIZE);
107        if (IS_ERR(path))
108                return PTR_ERR(path);
109
110        fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
111        if (IS_ERR(fs_path))
112                return PTR_ERR(fs_path);
113
114        if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
115                dprintk("%s: path %s does not begin with fsroot %s\n",
116                        __func__, path, fs_path);
117                return -ENOENT;
118        }
119
120        return 0;
121}
122
123static size_t nfs_parse_server_name(char *string, size_t len,
124                struct sockaddr *sa, size_t salen, struct net *net)
125{
126        ssize_t ret;
127
128        ret = rpc_pton(net, string, len, sa, salen);
129        if (ret == 0) {
130                ret = nfs_dns_resolve_name(net, string, len, sa, salen);
131                if (ret < 0)
132                        ret = 0;
133        }
134        return ret;
135}
136
137/**
138 * nfs_find_best_sec - Find a security mechanism supported locally
139 * @server: NFS server struct
140 * @flavors: List of security tuples returned by SECINFO procedure
141 *
142 * Return an rpc client that uses the first security mechanism in
143 * "flavors" that is locally supported.  The "flavors" array
144 * is searched in the order returned from the server, per RFC 3530
145 * recommendation and each flavor is checked for membership in the
146 * sec= mount option list if it exists.
147 *
148 * Return -EPERM if no matching flavor is found in the array.
149 *
150 * Please call rpc_shutdown_client() when you are done with this rpc client.
151 *
152 */
153static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt,
154                                          struct nfs_server *server,
155                                          struct nfs4_secinfo_flavors *flavors)
156{
157        rpc_authflavor_t pflavor;
158        struct nfs4_secinfo4 *secinfo;
159        unsigned int i;
160
161        for (i = 0; i < flavors->num_flavors; i++) {
162                secinfo = &flavors->flavors[i];
163
164                switch (secinfo->flavor) {
165                case RPC_AUTH_NULL:
166                case RPC_AUTH_UNIX:
167                case RPC_AUTH_GSS:
168                        pflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
169                                                        &secinfo->flavor_info);
170                        /* does the pseudoflavor match a sec= mount opt? */
171                        if (pflavor != RPC_AUTH_MAXFLAVOR &&
172                            nfs_auth_info_match(&server->auth_info, pflavor)) {
173                                struct rpc_clnt *new;
174                                struct rpc_cred *cred;
175
176                                /* Cloning creates an rpc_auth for the flavor */
177                                new = rpc_clone_client_set_auth(clnt, pflavor);
178                                if (IS_ERR(new))
179                                        continue;
180                                /**
181                                * Check that the user actually can use the
182                                * flavor. This is mostly for RPC_AUTH_GSS
183                                * where cr_init obtains a gss context
184                                */
185                                cred = rpcauth_lookupcred(new->cl_auth, 0);
186                                if (IS_ERR(cred)) {
187                                        rpc_shutdown_client(new);
188                                        continue;
189                                }
190                                put_rpccred(cred);
191                                return new;
192                        }
193                }
194        }
195        return ERR_PTR(-EPERM);
196}
197
198/**
199 * nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup,
200 * return an rpc_clnt that uses the best available security flavor with
201 * respect to the secinfo flavor list and the sec= mount options.
202 *
203 * @clnt: RPC client to clone
204 * @inode: directory inode
205 * @name: lookup name
206 *
207 * Please call rpc_shutdown_client() when you are done with this rpc client.
208 */
209struct rpc_clnt *
210nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode,
211                                        const struct qstr *name)
212{
213        struct page *page;
214        struct nfs4_secinfo_flavors *flavors;
215        struct rpc_clnt *new;
216        int err;
217
218        page = alloc_page(GFP_KERNEL);
219        if (!page)
220                return ERR_PTR(-ENOMEM);
221
222        flavors = page_address(page);
223
224        err = nfs4_proc_secinfo(inode, name, flavors);
225        if (err < 0) {
226                new = ERR_PTR(err);
227                goto out;
228        }
229
230        new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors);
231
232out:
233        put_page(page);
234        return new;
235}
236
237static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
238                                     char *page, char *page2,
239                                     const struct nfs4_fs_location *location)
240{
241        const size_t addr_bufsize = sizeof(struct sockaddr_storage);
242        struct net *net = rpc_net_ns(NFS_SB(mountdata->sb)->client);
243        struct vfsmount *mnt = ERR_PTR(-ENOENT);
244        char *mnt_path;
245        unsigned int maxbuflen;
246        unsigned int s;
247
248        mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
249        if (IS_ERR(mnt_path))
250                return ERR_CAST(mnt_path);
251        mountdata->mnt_path = mnt_path;
252        maxbuflen = mnt_path - 1 - page2;
253
254        mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
255        if (mountdata->addr == NULL)
256                return ERR_PTR(-ENOMEM);
257
258        for (s = 0; s < location->nservers; s++) {
259                const struct nfs4_string *buf = &location->servers[s];
260
261                if (buf->len <= 0 || buf->len >= maxbuflen)
262                        continue;
263
264                if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
265                        continue;
266
267                mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
268                                mountdata->addr, addr_bufsize, net);
269                if (mountdata->addrlen == 0)
270                        continue;
271
272                rpc_set_port(mountdata->addr, NFS_PORT);
273
274                memcpy(page2, buf->data, buf->len);
275                page2[buf->len] = '\0';
276                mountdata->hostname = page2;
277
278                snprintf(page, PAGE_SIZE, "%s:%s",
279                                mountdata->hostname,
280                                mountdata->mnt_path);
281
282                mnt = vfs_submount(mountdata->dentry, &nfs4_referral_fs_type, page, mountdata);
283                if (!IS_ERR(mnt))
284                        break;
285        }
286        kfree(mountdata->addr);
287        return mnt;
288}
289
290/**
291 * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
292 * @dentry - parent directory
293 * @locations - array of NFSv4 server location information
294 *
295 */
296static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
297                                            const struct nfs4_fs_locations *locations)
298{
299        struct vfsmount *mnt = ERR_PTR(-ENOENT);
300        struct nfs_clone_mount mountdata = {
301                .sb = dentry->d_sb,
302                .dentry = dentry,
303                .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
304        };
305        char *page = NULL, *page2 = NULL;
306        int loc, error;
307
308        if (locations == NULL || locations->nlocations <= 0)
309                goto out;
310
311        dprintk("%s: referral at %pd2\n", __func__, dentry);
312
313        page = (char *) __get_free_page(GFP_USER);
314        if (!page)
315                goto out;
316
317        page2 = (char *) __get_free_page(GFP_USER);
318        if (!page2)
319                goto out;
320
321        /* Ensure fs path is a prefix of current dentry path */
322        error = nfs4_validate_fspath(dentry, locations, page, page2);
323        if (error < 0) {
324                mnt = ERR_PTR(error);
325                goto out;
326        }
327
328        for (loc = 0; loc < locations->nlocations; loc++) {
329                const struct nfs4_fs_location *location = &locations->locations[loc];
330
331                if (location == NULL || location->nservers <= 0 ||
332                    location->rootpath.ncomponents == 0)
333                        continue;
334
335                mnt = try_location(&mountdata, page, page2, location);
336                if (!IS_ERR(mnt))
337                        break;
338        }
339
340out:
341        free_page((unsigned long) page);
342        free_page((unsigned long) page2);
343        dprintk("%s: done\n", __func__);
344        return mnt;
345}
346
347/*
348 * nfs_do_refmount - handle crossing a referral on server
349 * @dentry - dentry of referral
350 *
351 */
352static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
353{
354        struct vfsmount *mnt = ERR_PTR(-ENOMEM);
355        struct dentry *parent;
356        struct nfs4_fs_locations *fs_locations = NULL;
357        struct page *page;
358        int err;
359
360        /* BUG_ON(IS_ROOT(dentry)); */
361        dprintk("%s: enter\n", __func__);
362
363        page = alloc_page(GFP_KERNEL);
364        if (page == NULL)
365                goto out;
366
367        fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
368        if (fs_locations == NULL)
369                goto out_free;
370
371        /* Get locations */
372        mnt = ERR_PTR(-ENOENT);
373
374        parent = dget_parent(dentry);
375        dprintk("%s: getting locations for %pd2\n",
376                __func__, dentry);
377
378        err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page);
379        dput(parent);
380        if (err != 0 ||
381            fs_locations->nlocations <= 0 ||
382            fs_locations->fs_path.ncomponents <= 0)
383                goto out_free;
384
385        mnt = nfs_follow_referral(dentry, fs_locations);
386out_free:
387        __free_page(page);
388        kfree(fs_locations);
389out:
390        dprintk("%s: done\n", __func__);
391        return mnt;
392}
393
394struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
395                               struct nfs_fh *fh, struct nfs_fattr *fattr)
396{
397        rpc_authflavor_t flavor = server->client->cl_auth->au_flavor;
398        struct dentry *parent = dget_parent(dentry);
399        struct inode *dir = d_inode(parent);
400        const struct qstr *name = &dentry->d_name;
401        struct rpc_clnt *client;
402        struct vfsmount *mnt;
403
404        /* Look it up again to get its attributes and sec flavor */
405        client = nfs4_proc_lookup_mountpoint(dir, name, fh, fattr);
406        dput(parent);
407        if (IS_ERR(client))
408                return ERR_CAST(client);
409
410        if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
411                mnt = nfs_do_refmount(client, dentry);
412                goto out;
413        }
414
415        if (client->cl_auth->au_flavor != flavor)
416                flavor = client->cl_auth->au_flavor;
417        mnt = nfs_do_submount(dentry, fh, fattr, flavor);
418out:
419        rpc_shutdown_client(client);
420        return mnt;
421}
422
423/*
424 * Try one location from the fs_locations array.
425 *
426 * Returns zero on success, or a negative errno value.
427 */
428static int nfs4_try_replacing_one_location(struct nfs_server *server,
429                char *page, char *page2,
430                const struct nfs4_fs_location *location)
431{
432        const size_t addr_bufsize = sizeof(struct sockaddr_storage);
433        struct net *net = rpc_net_ns(server->client);
434        struct sockaddr *sap;
435        unsigned int s;
436        size_t salen;
437        int error;
438
439        sap = kmalloc(addr_bufsize, GFP_KERNEL);
440        if (sap == NULL)
441                return -ENOMEM;
442
443        error = -ENOENT;
444        for (s = 0; s < location->nservers; s++) {
445                const struct nfs4_string *buf = &location->servers[s];
446                char *hostname;
447
448                if (buf->len <= 0 || buf->len > PAGE_SIZE)
449                        continue;
450
451                if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL)
452                        continue;
453
454                salen = nfs_parse_server_name(buf->data, buf->len,
455                                                sap, addr_bufsize, net);
456                if (salen == 0)
457                        continue;
458                rpc_set_port(sap, NFS_PORT);
459
460                error = -ENOMEM;
461                hostname = kstrndup(buf->data, buf->len, GFP_KERNEL);
462                if (hostname == NULL)
463                        break;
464
465                error = nfs4_update_server(server, hostname, sap, salen, net);
466                kfree(hostname);
467                if (error == 0)
468                        break;
469        }
470
471        kfree(sap);
472        return error;
473}
474
475/**
476 * nfs4_replace_transport - set up transport to destination server
477 *
478 * @server: export being migrated
479 * @locations: fs_locations array
480 *
481 * Returns zero on success, or a negative errno value.
482 *
483 * The client tries all the entries in the "locations" array, in the
484 * order returned by the server, until one works or the end of the
485 * array is reached.
486 */
487int nfs4_replace_transport(struct nfs_server *server,
488                           const struct nfs4_fs_locations *locations)
489{
490        char *page = NULL, *page2 = NULL;
491        int loc, error;
492
493        error = -ENOENT;
494        if (locations == NULL || locations->nlocations <= 0)
495                goto out;
496
497        error = -ENOMEM;
498        page = (char *) __get_free_page(GFP_USER);
499        if (!page)
500                goto out;
501        page2 = (char *) __get_free_page(GFP_USER);
502        if (!page2)
503                goto out;
504
505        for (loc = 0; loc < locations->nlocations; loc++) {
506                const struct nfs4_fs_location *location =
507                                                &locations->locations[loc];
508
509                if (location == NULL || location->nservers <= 0 ||
510                    location->rootpath.ncomponents == 0)
511                        continue;
512
513                error = nfs4_try_replacing_one_location(server, page,
514                                                        page2, location);
515                if (error == 0)
516                        break;
517        }
518
519out:
520        free_page((unsigned long)page);
521        free_page((unsigned long)page2);
522        return error;
523}
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