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2024-02-20 e636c8d336489bf3eed5878299e6cc045bbad077 
 kernel/fs/cifs/cifs_dfs_ref.c
....@@ -1,3 +1,4 @@
1
+// SPDX-License-Identifier: GPL-2.0-or-later
12 /*
23  *   Contains the CIFS DFS referral mounting routines used for handling
34  *   traversal via DFS junction point
....@@ -6,10 +7,6 @@
67  *   Copyright (C) International Business Machines  Corp., 2008
78  *   Author(s): Igor Mammedov (niallain@gmail.com)
89  *		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.
1310  */
1411 
1512 #include <linux/dcache.h>
....@@ -25,6 +22,7 @@
2522 #include "dns_resolve.h"
2623 #include "cifs_debug.h"
2724 #include "cifs_unicode.h"
25
+#include "dfs_cache.h"
2826 
2927 static LIST_HEAD(cifs_dfs_automount_list);
3028 
....@@ -122,17 +120,17 @@
122120 
123121 
124122 /**
125
- * cifs_compose_mount_options	-	creates mount options for refferral
123
+ * cifs_compose_mount_options	-	creates mount options for referral
126124  * @sb_mountdata:	parent/root DFS mount options (template)
127125  * @fullpath:		full path in UNC format
128
- * @ref:		server's referral
129
- * @devname:		pointer for saving device name
126
+ * @ref:		optional server's referral
127
+ * @devname:		optional pointer for saving device name
130128  *
131129  * creates mount options for submount based on template options sb_mountdata
132130  * and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
133131  *
134132  * Returns: pointer to new mount options or ERR_PTR.
135
- * Caller is responcible for freeing retunrned value if it is not error.
133
+ * Caller is responsible for freeing returned value if it is not error.
136134  */
137135 char *cifs_compose_mount_options(const char *sb_mountdata,
138136 				   const char *fullpath,
....@@ -140,6 +138,7 @@
140138 				   char **devname)
141139 {
142140 	int rc;
141
+	char *name;
143142 	char *mountdata = NULL;
144143 	const char *prepath = NULL;
145144 	int md_len;
....@@ -151,24 +150,36 @@
151150 	if (sb_mountdata == NULL)
152151 		return ERR_PTR(-EINVAL);
153152 
154
-	if (strlen(fullpath) - ref->path_consumed) {
155
-		prepath = fullpath + ref->path_consumed;
156
-		/* skip initial delimiter */
157
-		if (*prepath == '/' || *prepath == '\\')
158
-			prepath++;
153
+	if (ref) {
154
+		if (WARN_ON_ONCE(!ref->node_name || ref->path_consumed < 0))
155
+			return ERR_PTR(-EINVAL);
156
+
157
+		if (strlen(fullpath) - ref->path_consumed) {
158
+			prepath = fullpath + ref->path_consumed;
159
+			/* skip initial delimiter */
160
+			if (*prepath == '/' || *prepath == '\\')
161
+				prepath++;
162
+		}
163
+
164
+		name = cifs_build_devname(ref->node_name, prepath);
165
+		if (IS_ERR(name)) {
166
+			rc = PTR_ERR(name);
167
+			name = NULL;
168
+			goto compose_mount_options_err;
169
+		}
170
+	} else {
171
+		name = cifs_build_devname((char *)fullpath, NULL);
172
+		if (IS_ERR(name)) {
173
+			rc = PTR_ERR(name);
174
+			name = NULL;
175
+			goto compose_mount_options_err;
176
+		}
159177 	}
160178 
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);
179
+	rc = dns_resolve_server_name_to_ip(name, &srvIP);
169180 	if (rc < 0) {
170181 		cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
171
-			 __func__, *devname, rc);
182
+			 __func__, name, rc);
172183 		goto compose_mount_options_err;
173184 	}
174185 
....@@ -224,6 +235,11 @@
224235 	strcat(mountdata, "ip=");
225236 	strcat(mountdata, srvIP);
226237 
238
+	if (devname)
239
+		*devname = name;
240
+	else
241
+		kfree(name);
242
+
227243 	/*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/
228244 	/*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );*/
229245 
....@@ -234,47 +250,46 @@
234250 compose_mount_options_err:
235251 	kfree(mountdata);
236252 	mountdata = ERR_PTR(rc);
237
-	kfree(*devname);
238
-	*devname = NULL;
253
+	kfree(name);
239254 	goto compose_mount_options_out;
240255 }
241256 
242257 /**
243
- * cifs_dfs_do_refmount - mounts specified path using provided refferal
258
+ * cifs_dfs_do_mount - mounts specified path using DFS full path
259
+ *
260
+ * Always pass down @fullpath to smb3_do_mount() so we can use the root server
261
+ * to perform failover in case we failed to connect to the first target in the
262
+ * referral.
263
+ *
244264  * @cifs_sb:		parent/root superblock
245265  * @fullpath:		full path in UNC format
246
- * @ref:		server's referral
247266  */
248
-static 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)
267
+static struct vfsmount *cifs_dfs_do_mount(struct dentry *mntpt,
268
+					  struct cifs_sb_info *cifs_sb,
269
+					  const char *fullpath)
251270 {
252271 	struct vfsmount *mnt;
253272 	char *mountdata;
254
-	char *devname = NULL;
273
+	char *devname;
274
+
275
+	devname = kstrndup(fullpath, strlen(fullpath), GFP_KERNEL);
276
+	if (!devname)
277
+		return ERR_PTR(-ENOMEM);
278
+
279
+	convert_delimiter(devname, '/');
255280 
256281 	/* strip first '\' from fullpath */
257282 	mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
258
-			fullpath + 1, ref, &devname);
259
-
260
-	if (IS_ERR(mountdata))
283
+					       fullpath + 1, NULL, NULL);
284
+	if (IS_ERR(mountdata)) {
285
+		kfree(devname);
261286 		return (struct vfsmount *)mountdata;
287
+	}
262288 
263289 	mnt = vfs_submount(mntpt, &cifs_fs_type, devname, mountdata);
264290 	kfree(mountdata);
265291 	kfree(devname);
266292 	return mnt;
267
-
268
-}
269
-
270
-static 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: %d, srv_type: %d\n",
275
-		 ref->flags, ref->server_type);
276
-	cifs_dbg(FYI, "DFS: ref_flags: %d, path_consumed: %d\n",
277
-		 ref->ref_flag, ref->path_consumed);
278293 }
279294 
280295 /*
....@@ -282,16 +297,13 @@
282297  */
283298 static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
284299 {
285
-	struct dfs_info3_param *referrals = NULL;
286
-	unsigned int num_referrals = 0;
287300 	struct cifs_sb_info *cifs_sb;
288301 	struct cifs_ses *ses;
289
-	char *full_path;
302
+	struct cifs_tcon *tcon;
303
+	char *full_path, *root_path;
290304 	unsigned int xid;
291
-	int i;
292305 	int rc;
293306 	struct vfsmount *mnt;
294
-	struct tcon_link *tlink;
295307 
296308 	cifs_dbg(FYI, "in %s\n", __func__);
297309 	BUG_ON(IS_ROOT(mntpt));
....@@ -304,54 +316,72 @@
304316 	 */
305317 	mnt = ERR_PTR(-ENOMEM);
306318 
319
+	cifs_sb = CIFS_SB(mntpt->d_sb);
320
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) {
321
+		mnt = ERR_PTR(-EREMOTE);
322
+		goto cdda_exit;
323
+	}
324
+
307325 	/* always use tree name prefix */
308326 	full_path = build_path_from_dentry_optional_prefix(mntpt, true);
309327 	if (full_path == NULL)
310328 		goto cdda_exit;
311329 
312
-	cifs_sb = CIFS_SB(mntpt->d_sb);
313
-	tlink = cifs_sb_tlink(cifs_sb);
314
-	if (IS_ERR(tlink)) {
315
-		mnt = ERR_CAST(tlink);
330
+	convert_delimiter(full_path, '\\');
331
+
332
+	cifs_dbg(FYI, "%s: full_path: %s\n", __func__, full_path);
333
+
334
+	if (!cifs_sb_master_tlink(cifs_sb)) {
335
+		cifs_dbg(FYI, "%s: master tlink is NULL\n", __func__);
316336 		goto free_full_path;
317337 	}
318
-	ses = tlink_tcon(tlink)->ses;
319338 
320
-	xid = get_xid();
321
-	rc = get_dfs_path(xid, ses, full_path + 1, cifs_sb->local_nls,
322
-		&num_referrals, &referrals,
323
-		cifs_remap(cifs_sb));
324
-	free_xid(xid);
325
-
326
-	cifs_put_tlink(tlink);
327
-
328
-	mnt = ERR_PTR(-ENOENT);
329
-	for (i = 0; i < num_referrals; i++) {
330
-		int len;
331
-		dump_referral(referrals + i);
332
-		/* connect to a node */
333
-		len = strlen(referrals[i].node_name);
334
-		if (len < 2) {
335
-			cifs_dbg(VFS, "%s: Net Address path too short: %s\n",
336
-				 __func__, referrals[i].node_name);
337
-			mnt = ERR_PTR(-EINVAL);
338
-			break;
339
-		}
340
-		mnt = cifs_dfs_do_refmount(mntpt, cifs_sb,
341
-				full_path, referrals + i);
342
-		cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n",
343
-			 __func__, referrals[i].node_name, mnt);
344
-		if (!IS_ERR(mnt))
345
-			goto success;
339
+	tcon = cifs_sb_master_tcon(cifs_sb);
340
+	if (!tcon) {
341
+		cifs_dbg(FYI, "%s: master tcon is NULL\n", __func__);
342
+		goto free_full_path;
346343 	}
347344 
348
-	/* no valid submounts were found; return error from get_dfs_path() by
349
-	 * preference */
350
-	if (rc != 0)
351
-		mnt = ERR_PTR(rc);
345
+	root_path = kstrdup(tcon->treeName, GFP_KERNEL);
346
+	if (!root_path) {
347
+		mnt = ERR_PTR(-ENOMEM);
348
+		goto free_full_path;
349
+	}
350
+	cifs_dbg(FYI, "%s: root path: %s\n", __func__, root_path);
352351 
353
-success:
354
-	free_dfs_info_array(referrals, num_referrals);
352
+	ses = tcon->ses;
353
+	xid = get_xid();
354
+
355
+	/*
356
+	 * If DFS root has been expired, then unconditionally fetch it again to
357
+	 * refresh DFS referral cache.
358
+	 */
359
+	rc = dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),
360
+			    root_path + 1, NULL, NULL);
361
+	if (!rc) {
362
+		rc = dfs_cache_find(xid, ses, cifs_sb->local_nls,
363
+				    cifs_remap(cifs_sb), full_path + 1,
364
+				    NULL, NULL);
365
+	}
366
+
367
+	free_xid(xid);
368
+
369
+	if (rc) {
370
+		mnt = ERR_PTR(rc);
371
+		goto free_root_path;
372
+	}
373
+	/*
374
+	 * OK - we were able to get and cache a referral for @full_path.
375
+	 *
376
+	 * Now, pass it down to cifs_mount() and it will retry every available
377
+	 * node server in case of failures - no need to do it here.
378
+	 */
379
+	mnt = cifs_dfs_do_mount(mntpt, cifs_sb, full_path);
380
+	cifs_dbg(FYI, "%s: cifs_dfs_do_mount:%s , mnt:%p\n", __func__,
381
+		 full_path + 1, mnt);
382
+
383
+free_root_path:
384
+	kfree(root_path);
355385 free_full_path:
356386 	kfree(full_path);
357387 cdda_exit: