source: src/linux/universal/linux-4.9/fs/cifs/cifs_dfs_ref.c @ 31662

Last change on this file since 31662 was 31662, checked in by brainslayer, 4 months ago

use new squashfs in all kernels

File size: 9.9 KB
Line 
1/*
2 *   Contains the CIFS DFS referral mounting routines used for handling
3 *   traversal via DFS junction point
4 *
5 *   Copyright (c) 2007 Igor Mammedov
6 *   Copyright (C) International Business Machines  Corp., 2008
7 *   Author(s): Igor Mammedov (niallain@gmail.com)
8 *              Steve French (sfrench@us.ibm.com)
9 *   This program is free software; you can redistribute it and/or
10 *   modify it under the terms of the GNU General Public License
11 *   as published by the Free Software Foundation; either version
12 *   2 of the License, or (at your option) any later version.
13 */
14
15#include <linux/dcache.h>
16#include <linux/mount.h>
17#include <linux/namei.h>
18#include <linux/slab.h>
19#include <linux/vfs.h>
20#include <linux/fs.h>
21#include <linux/inet.h>
22#include "cifsglob.h"
23#include "cifsproto.h"
24#include "cifsfs.h"
25#include "dns_resolve.h"
26#include "cifs_debug.h"
27#include "cifs_unicode.h"
28
29static LIST_HEAD(cifs_dfs_automount_list);
30
31static void cifs_dfs_expire_automounts(struct work_struct *work);
32static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
33                            cifs_dfs_expire_automounts);
34static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
35
36static void cifs_dfs_expire_automounts(struct work_struct *work)
37{
38        struct list_head *list = &cifs_dfs_automount_list;
39
40        mark_mounts_for_expiry(list);
41        if (!list_empty(list))
42                schedule_delayed_work(&cifs_dfs_automount_task,
43                                      cifs_dfs_mountpoint_expiry_timeout);
44}
45
46void cifs_dfs_release_automount_timer(void)
47{
48        BUG_ON(!list_empty(&cifs_dfs_automount_list));
49        cancel_delayed_work_sync(&cifs_dfs_automount_task);
50}
51
52/**
53 * cifs_build_devname - build a devicename from a UNC and optional prepath
54 * @nodename:   pointer to UNC string
55 * @prepath:    pointer to prefixpath (or NULL if there isn't one)
56 *
57 * Build a new cifs devicename after chasing a DFS referral. Allocate a buffer
58 * big enough to hold the final thing. Copy the UNC from the nodename, and
59 * concatenate the prepath onto the end of it if there is one.
60 *
61 * Returns pointer to the built string, or a ERR_PTR. Caller is responsible
62 * for freeing the returned string.
63 */
64static char *
65cifs_build_devname(char *nodename, const char *prepath)
66{
67        size_t pplen;
68        size_t unclen;
69        char *dev;
70        char *pos;
71
72        /* skip over any preceding delimiters */
73        nodename += strspn(nodename, "\\");
74        if (!*nodename)
75                return ERR_PTR(-EINVAL);
76
77        /* get length of UNC and set pos to last char */
78        unclen = strlen(nodename);
79        pos = nodename + unclen - 1;
80
81        /* trim off any trailing delimiters */
82        while (*pos == '\\') {
83                --pos;
84                --unclen;
85        }
86
87        /* allocate a buffer:
88         * +2 for preceding "//"
89         * +1 for delimiter between UNC and prepath
90         * +1 for trailing NULL
91         */
92        pplen = prepath ? strlen(prepath) : 0;
93        dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL);
94        if (!dev)
95                return ERR_PTR(-ENOMEM);
96
97        pos = dev;
98        /* add the initial "//" */
99        *pos = '/';
100        ++pos;
101        *pos = '/';
102        ++pos;
103
104        /* copy in the UNC portion from referral */
105        memcpy(pos, nodename, unclen);
106        pos += unclen;
107
108        /* copy the prefixpath remainder (if there is one) */
109        if (pplen) {
110                *pos = '/';
111                ++pos;
112                memcpy(pos, prepath, pplen);
113                pos += pplen;
114        }
115
116        /* NULL terminator */
117        *pos = '\0';
118
119        convert_delimiter(dev, '/');
120        return dev;
121}
122
123
124/**
125 * cifs_compose_mount_options   -       creates mount options for refferral
126 * @sb_mountdata:       parent/root DFS mount options (template)
127 * @fullpath:           full path in UNC format
128 * @ref:                server's referral
129 * @devname:            pointer for saving device name
130 *
131 * creates mount options for submount based on template options sb_mountdata
132 * and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
133 *
134 * Returns: pointer to new mount options or ERR_PTR.
135 * Caller is responcible for freeing retunrned value if it is not error.
136 */
137char *cifs_compose_mount_options(const char *sb_mountdata,
138                                   const char *fullpath,
139                                   const struct dfs_info3_param *ref,
140                                   char **devname)
141{
142        int rc;
143        char *mountdata = NULL;
144        const char *prepath = NULL;
145        int md_len;
146        char *tkn_e;
147        char *srvIP = NULL;
148        char sep = ',';
149        int off, noff;
150
151        if (sb_mountdata == NULL)
152                return ERR_PTR(-EINVAL);
153
154        if (strlen(fullpath) - ref->path_consumed) {
155                prepath = fullpath + ref->path_consumed;
156                /* skip initial delimiter */
157                if (*prepath == '/' || *prepath == '\\')
158                        prepath++;
159        }
160
161        *devname = cifs_build_devname(ref->node_name, prepath);
162        if (IS_ERR(*devname)) {
163                rc = PTR_ERR(*devname);
164                *devname = NULL;
165                goto compose_mount_options_err;
166        }
167
168        rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
169        if (rc < 0) {
170                cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
171                         __func__, *devname, rc);
172                goto compose_mount_options_err;
173        }
174
175        /*
176         * In most cases, we'll be building a shorter string than the original,
177         * but we do have to assume that the address in the ip= option may be
178         * much longer than the original. Add the max length of an address
179         * string to the length of the original string to allow for worst case.
180         */
181        md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;
182        mountdata = kzalloc(md_len + sizeof("ip=") + 1, GFP_KERNEL);
183        if (mountdata == NULL) {
184                rc = -ENOMEM;
185                goto compose_mount_options_err;
186        }
187
188        /* copy all options except of unc,ip,prefixpath */
189        off = 0;
190        if (strncmp(sb_mountdata, "sep=", 4) == 0) {
191                        sep = sb_mountdata[4];
192                        strncpy(mountdata, sb_mountdata, 5);
193                        off += 5;
194        }
195
196        do {
197                tkn_e = strchr(sb_mountdata + off, sep);
198                if (tkn_e == NULL)
199                        noff = strlen(sb_mountdata + off);
200                else
201                        noff = tkn_e - (sb_mountdata + off) + 1;
202
203                if (strncasecmp(sb_mountdata + off, "unc=", 4) == 0) {
204                        off += noff;
205                        continue;
206                }
207                if (strncasecmp(sb_mountdata + off, "ip=", 3) == 0) {
208                        off += noff;
209                        continue;
210                }
211                if (strncasecmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
212                        off += noff;
213                        continue;
214                }
215                strncat(mountdata, sb_mountdata + off, noff);
216                off += noff;
217        } while (tkn_e);
218        strcat(mountdata, sb_mountdata + off);
219        mountdata[md_len] = '\0';
220
221        /* copy new IP and ref share name */
222        if (mountdata[strlen(mountdata) - 1] != sep)
223                strncat(mountdata, &sep, 1);
224        strcat(mountdata, "ip=");
225        strcat(mountdata, srvIP);
226
227        /*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/
228        /*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );*/
229
230compose_mount_options_out:
231        kfree(srvIP);
232        return mountdata;
233
234compose_mount_options_err:
235        kfree(mountdata);
236        mountdata = ERR_PTR(rc);
237        kfree(*devname);
238        *devname = NULL;
239        goto compose_mount_options_out;
240}
241
242/**
243 * cifs_dfs_do_refmount - mounts specified path using provided refferal
244 * @cifs_sb:            parent/root superblock
245 * @fullpath:           full path in UNC format
246 * @ref:                server's referral
247 */
248static struct vfsmount *cifs_dfs_do_refmount(struct dentry *mntpt,
249                struct cifs_sb_info *cifs_sb,
250                const char *fullpath, const struct dfs_info3_param *ref)
251{
252        struct vfsmount *mnt;
253        char *mountdata;
254        char *devname = NULL;
255
256        /* strip first '\' from fullpath */
257        mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
258                        fullpath + 1, ref, &devname);
259
260        if (IS_ERR(mountdata))
261                return (struct vfsmount *)mountdata;
262
263        mnt = vfs_submount(mntpt, &cifs_fs_type, devname, mountdata);
264        kfree(mountdata);
265        kfree(devname);
266        return mnt;
267
268}
269
270static void dump_referral(const struct dfs_info3_param *ref)
271{
272        cifs_dbg(FYI, "DFS: ref path: %s\n", ref->path_name);
273        cifs_dbg(FYI, "DFS: node path: %s\n", ref->node_name);
274        cifs_dbg(FYI, "DFS: fl: %hd, srv_type: %hd\n",
275                 ref->flags, ref->server_type);
276        cifs_dbg(FYI, "DFS: ref_flags: %hd, path_consumed: %hd\n",
277                 ref->ref_flag, ref->path_consumed);
278}
279
280/*
281 * Create a vfsmount that we can automount
282 */
283static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
284{
285        struct dfs_info3_param *referrals = NULL;
286        unsigned int num_referrals = 0;
287        struct cifs_sb_info *cifs_sb;
288        struct cifs_ses *ses;
289        char *full_path;
290        unsigned int xid;
291        int i;
292        int rc;
293        struct vfsmount *mnt;
294        struct tcon_link *tlink;
295
296        cifs_dbg(FYI, "in %s\n", __func__);
297        BUG_ON(IS_ROOT(mntpt));
298
299        /*
300         * The MSDFS spec states that paths in DFS referral requests and
301         * responses must be prefixed by a single '\' character instead of
302         * the double backslashes usually used in the UNC. This function
303         * gives us the latter, so we must adjust the result.
304         */
305        mnt = ERR_PTR(-ENOMEM);
306        full_path = build_path_from_dentry(mntpt);
307        if (full_path == NULL)
308                goto cdda_exit;
309
310        cifs_sb = CIFS_SB(mntpt->d_sb);
311        tlink = cifs_sb_tlink(cifs_sb);
312        if (IS_ERR(tlink)) {
313                mnt = ERR_CAST(tlink);
314                goto free_full_path;
315        }
316        ses = tlink_tcon(tlink)->ses;
317
318        xid = get_xid();
319        rc = get_dfs_path(xid, ses, full_path + 1, cifs_sb->local_nls,
320                &num_referrals, &referrals,
321                cifs_remap(cifs_sb));
322        free_xid(xid);
323
324        cifs_put_tlink(tlink);
325
326        mnt = ERR_PTR(-ENOENT);
327        for (i = 0; i < num_referrals; i++) {
328                int len;
329                dump_referral(referrals + i);
330                /* connect to a node */
331                len = strlen(referrals[i].node_name);
332                if (len < 2) {
333                        cifs_dbg(VFS, "%s: Net Address path too short: %s\n",
334                                 __func__, referrals[i].node_name);
335                        mnt = ERR_PTR(-EINVAL);
336                        break;
337                }
338                mnt = cifs_dfs_do_refmount(mntpt, cifs_sb,
339                                full_path, referrals + i);
340                cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n",
341                         __func__, referrals[i].node_name, mnt);
342                if (!IS_ERR(mnt))
343                        goto success;
344        }
345
346        /* no valid submounts were found; return error from get_dfs_path() by
347         * preference */
348        if (rc != 0)
349                mnt = ERR_PTR(rc);
350
351success:
352        free_dfs_info_array(referrals, num_referrals);
353free_full_path:
354        kfree(full_path);
355cdda_exit:
356        cifs_dbg(FYI, "leaving %s\n" , __func__);
357        return mnt;
358}
359
360/*
361 * Attempt to automount the referral
362 */
363struct vfsmount *cifs_dfs_d_automount(struct path *path)
364{
365        struct vfsmount *newmnt;
366
367        cifs_dbg(FYI, "in %s\n", __func__);
368
369        newmnt = cifs_dfs_do_automount(path->dentry);
370        if (IS_ERR(newmnt)) {
371                cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__);
372                return newmnt;
373        }
374
375        mntget(newmnt); /* prevent immediate expiration */
376        mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
377        schedule_delayed_work(&cifs_dfs_automount_task,
378                              cifs_dfs_mountpoint_expiry_timeout);
379        cifs_dbg(FYI, "leaving %s [ok]\n" , __func__);
380        return newmnt;
381}
382
383const struct inode_operations cifs_dfs_referral_inode_operations = {
384};
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