1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
24  * Copyright (c) 2011,2012 Turbo Fredriksson <turbo@bayour.com>, based on nfs.c
25  *                         by Gunnar Beutner
26  * Copyright (c) 2019, 2020 by Delphix. All rights reserved.
27  *
28  * This is an addition to the zfs device driver to add, modify and remove SMB
29  * shares using the 'net share' command that comes with Samba.
30  *
31  * TESTING
32  * Make sure that samba listens to 'localhost' (127.0.0.1) and that the options
33  * 'usershare max shares' and 'usershare owner only' have been reviewed/set
34  * accordingly (see zfs(8) for information).
35  *
36  * Once configuration in samba have been done, test that this
37  * works with the following three commands (in this case, my ZFS
38  * filesystem is called 'share/Test1'):
39  *
40  *	(root)# net -U root -S 127.0.0.1 usershare add Test1 /share/Test1 \
41  *		"Comment: /share/Test1" "Everyone:F"
42  *	(root)# net usershare list | grep -i test
43  *	(root)# net -U root -S 127.0.0.1 usershare delete Test1
44  *
45  * The first command will create a user share that gives everyone full access.
46  * To limit the access below that, use normal UNIX commands (chmod, chown etc).
47  */
48 
49 #include <time.h>
50 #include <stdlib.h>
51 #include <stdio.h>
52 #include <string.h>
53 #include <fcntl.h>
54 #include <sys/wait.h>
55 #include <unistd.h>
56 #include <dirent.h>
57 #include <sys/types.h>
58 #include <sys/stat.h>
59 #include <libzfs.h>
60 #include <libshare.h>
61 #include "libshare_impl.h"
62 #include "smb.h"
63 
64 static boolean_t smb_available(void);
65 
66 static smb_share_t *smb_shares;
67 static int smb_disable_share(sa_share_impl_t impl_share);
68 static boolean_t smb_is_share_active(sa_share_impl_t impl_share);
69 
70 /*
71  * Retrieve the list of SMB shares.
72  */
73 static int
74 smb_retrieve_shares(void)
75 {
76 	int rc = SA_OK;
77 	char file_path[PATH_MAX], line[512], *token, *key, *value;
78 	char *dup_value = NULL, *path = NULL, *comment = NULL, *name = NULL;
79 	char *guest_ok = NULL;
80 	DIR *shares_dir;
81 	FILE *share_file_fp = NULL;
82 	struct dirent *directory;
83 	struct stat eStat;
84 	smb_share_t *shares, *new_shares = NULL;
85 
86 	/* opendir(), stat() */
87 	shares_dir = opendir(SHARE_DIR);
88 	if (shares_dir == NULL)
89 		return (SA_SYSTEM_ERR);
90 
91 	/* Go through the directory, looking for shares */
92 	while ((directory = readdir(shares_dir))) {
93 		if (directory->d_name[0] == '.')
94 			continue;
95 
96 		snprintf(file_path, sizeof (file_path),
97 		    "%s/%s", SHARE_DIR, directory->d_name);
98 
99 		if (stat(file_path, &eStat) == -1) {
100 			rc = SA_SYSTEM_ERR;
101 			goto out;
102 		}
103 
104 		if (!S_ISREG(eStat.st_mode))
105 			continue;
106 
107 		if ((share_file_fp = fopen(file_path, "re")) == NULL) {
108 			rc = SA_SYSTEM_ERR;
109 			goto out;
110 		}
111 
112 		name = strdup(directory->d_name);
113 		if (name == NULL) {
114 			rc = SA_NO_MEMORY;
115 			goto out;
116 		}
117 
118 		while (fgets(line, sizeof (line), share_file_fp)) {
119 			if (line[0] == '#')
120 				continue;
121 
122 			/* Trim trailing new-line character(s). */
123 			while (line[strlen(line) - 1] == '\r' ||
124 			    line[strlen(line) - 1] == '\n')
125 				line[strlen(line) - 1] = '\0';
126 
127 			/* Split the line in two, separated by '=' */
128 			token = strchr(line, '=');
129 			if (token == NULL)
130 				continue;
131 
132 			key = line;
133 			value = token + 1;
134 			*token = '\0';
135 
136 			dup_value = strdup(value);
137 			if (dup_value == NULL) {
138 				rc = SA_NO_MEMORY;
139 				goto out;
140 			}
141 
142 			if (strcmp(key, "path") == 0) {
143 				free(path);
144 				path = dup_value;
145 			} else if (strcmp(key, "comment") == 0) {
146 				free(comment);
147 				comment = dup_value;
148 			} else if (strcmp(key, "guest_ok") == 0) {
149 				free(guest_ok);
150 				guest_ok = dup_value;
151 			} else
152 				free(dup_value);
153 
154 			dup_value = NULL;
155 
156 			if (path == NULL || comment == NULL || guest_ok == NULL)
157 				continue; /* Incomplete share definition */
158 			else {
159 				shares = (smb_share_t *)
160 				    malloc(sizeof (smb_share_t));
161 				if (shares == NULL) {
162 					rc = SA_NO_MEMORY;
163 					goto out;
164 				}
165 
166 				(void) strlcpy(shares->name, name,
167 				    sizeof (shares->name));
168 
169 				(void) strlcpy(shares->path, path,
170 				    sizeof (shares->path));
171 
172 				(void) strlcpy(shares->comment, comment,
173 				    sizeof (shares->comment));
174 
175 				shares->guest_ok = atoi(guest_ok);
176 
177 				shares->next = new_shares;
178 				new_shares = shares;
179 
180 				free(path);
181 				free(comment);
182 				free(guest_ok);
183 
184 				path = NULL;
185 				comment = NULL;
186 				guest_ok = NULL;
187 			}
188 		}
189 
190 out:
191 		if (share_file_fp != NULL) {
192 			fclose(share_file_fp);
193 			share_file_fp = NULL;
194 		}
195 
196 		free(name);
197 		free(path);
198 		free(comment);
199 		free(guest_ok);
200 
201 		name = NULL;
202 		path = NULL;
203 		comment = NULL;
204 		guest_ok = NULL;
205 	}
206 	closedir(shares_dir);
207 
208 	smb_shares = new_shares;
209 
210 	return (rc);
211 }
212 
213 /*
214  * Used internally by smb_enable_share to enable sharing for a single host.
215  */
216 static int
217 smb_enable_share_one(const char *sharename, const char *sharepath)
218 {
219 	char name[SMB_NAME_MAX], comment[SMB_COMMENT_MAX];
220 
221 	/* Support ZFS share name regexp '[[:alnum:]_-.: ]' */
222 	strlcpy(name, sharename, sizeof (name));
223 	for (char *itr = name; *itr != '\0'; ++itr)
224 		switch (*itr) {
225 		case '/':
226 		case '-':
227 		case ':':
228 		case ' ':
229 			*itr = '_';
230 		}
231 
232 	/*
233 	 * CMD: net -S NET_CMD_ARG_HOST usershare add Test1 /share/Test1 \
234 	 *      "Comment" "Everyone:F"
235 	 */
236 	snprintf(comment, sizeof (comment), "Comment: %s", sharepath);
237 
238 	char *argv[] = {
239 		(char *)NET_CMD_PATH,
240 		(char *)"-S",
241 		(char *)NET_CMD_ARG_HOST,
242 		(char *)"usershare",
243 		(char *)"add",
244 		name,
245 		(char *)sharepath,
246 		comment,
247 		(char *)"Everyone:F",
248 		NULL,
249 	};
250 
251 	if (libzfs_run_process(argv[0], argv, 0) != 0)
252 		return (SA_SYSTEM_ERR);
253 
254 	/* Reload the share file */
255 	(void) smb_retrieve_shares();
256 
257 	return (SA_OK);
258 }
259 
260 /*
261  * Enables SMB sharing for the specified share.
262  */
263 static int
264 smb_enable_share(sa_share_impl_t impl_share)
265 {
266 	if (!smb_available())
267 		return (SA_SYSTEM_ERR);
268 
269 	if (smb_is_share_active(impl_share))
270 		smb_disable_share(impl_share);
271 
272 	if (impl_share->sa_shareopts == NULL) /* on/off */
273 		return (SA_SYSTEM_ERR);
274 
275 	if (strcmp(impl_share->sa_shareopts, "off") == 0)
276 		return (SA_OK);
277 
278 	/* Magic: Enable (i.e., 'create new') share */
279 	return (smb_enable_share_one(impl_share->sa_zfsname,
280 	    impl_share->sa_mountpoint));
281 }
282 
283 /*
284  * Used internally by smb_disable_share to disable sharing for a single host.
285  */
286 static int
287 smb_disable_share_one(const char *sharename)
288 {
289 	/* CMD: net -S NET_CMD_ARG_HOST usershare delete Test1 */
290 	char *argv[] = {
291 		(char *)NET_CMD_PATH,
292 		(char *)"-S",
293 		(char *)NET_CMD_ARG_HOST,
294 		(char *)"usershare",
295 		(char *)"delete",
296 		(char *)sharename,
297 		NULL,
298 	};
299 
300 	if (libzfs_run_process(argv[0], argv, 0) != 0)
301 		return (SA_SYSTEM_ERR);
302 	else
303 		return (SA_OK);
304 }
305 
306 /*
307  * Disables SMB sharing for the specified share.
308  */
309 static int
310 smb_disable_share(sa_share_impl_t impl_share)
311 {
312 	if (!smb_available()) {
313 		/*
314 		 * The share can't possibly be active, so nothing
315 		 * needs to be done to disable it.
316 		 */
317 		return (SA_OK);
318 	}
319 
320 	for (const smb_share_t *i = smb_shares; i != NULL; i = i->next)
321 		if (strcmp(impl_share->sa_mountpoint, i->path) == 0)
322 			return (smb_disable_share_one(i->name));
323 
324 	return (SA_OK);
325 }
326 
327 /*
328  * Checks whether the specified SMB share options are syntactically correct.
329  */
330 static int
331 smb_validate_shareopts(const char *shareopts)
332 {
333 	/* TODO: Accept 'name' and sec/acl (?) */
334 	if ((strcmp(shareopts, "off") == 0) || (strcmp(shareopts, "on") == 0))
335 		return (SA_OK);
336 
337 	return (SA_SYNTAX_ERR);
338 }
339 
340 /*
341  * Checks whether a share is currently active.
342  */
343 static boolean_t
344 smb_is_share_active(sa_share_impl_t impl_share)
345 {
346 	if (!smb_available())
347 		return (B_FALSE);
348 
349 	/* Retrieve the list of (possible) active shares */
350 	smb_retrieve_shares();
351 
352 	for (const smb_share_t *i = smb_shares; i != NULL; i = i->next)
353 		if (strcmp(impl_share->sa_mountpoint, i->path) == 0)
354 			return (B_TRUE);
355 
356 	return (B_FALSE);
357 }
358 
359 static int
360 smb_update_shares(void)
361 {
362 	/* Not implemented */
363 	return (0);
364 }
365 
366 const sa_fstype_t libshare_smb_type = {
367 	.enable_share = smb_enable_share,
368 	.disable_share = smb_disable_share,
369 	.is_shared = smb_is_share_active,
370 
371 	.validate_shareopts = smb_validate_shareopts,
372 	.commit_shares = smb_update_shares,
373 };
374 
375 /*
376  * Provides a convenient wrapper for determining SMB availability
377  */
378 static boolean_t
379 smb_available(void)
380 {
381 	static int avail;
382 
383 	if (!avail) {
384 		struct stat statbuf;
385 
386 		if (access(NET_CMD_PATH, F_OK) != 0 ||
387 		    lstat(SHARE_DIR, &statbuf) != 0 ||
388 		    !S_ISDIR(statbuf.st_mode))
389 			avail = -1;
390 		else
391 			avail = 1;
392 	}
393 
394 	return (avail == 1);
395 }
396