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 2005 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 /*
30  * This module contains functions used for reading and writing the scratch zone
31  * translation files.  These files are used by Live Upgrade to keep track of
32  * mappings between actual kernel zone names and the zones in an alternate boot
33  * environment.
34  *
35  * The functions are MT-safe.
36  *
37  * The file format looks like this:
38  *
39  *	<zonename>	<kernel-zonename>	<alt-root>
40  *
41  * The expected usage model is:
42  *
43  *	fp = zonecfg_open_scratch("", B_TRUE);
44  *	zonecfg_lock_scratch(fp);
45  *	if (zonecfg_find_scratch(fp, zonename, altroot, NULL, 0) == 0) {
46  *		handle error; zone already mounted
47  *	}
48  *	mount zone here
49  *	zonecfg_add_scratch(fp, zonename, kernname, altroot);
50  *	zonecfg_close_scratch(fp);
51  *	fp = zonecfg_open_scratch(zoneroot, B_TRUE);
52  *	ftruncate(fileno(fp), 0);
53  *	zonecfg_add_scratch(fp, zonename, kernname, "/");
54  *	zonecfg_close_scratch(fp);
55  */
56 
57 #include <stdio.h>
58 #include <unistd.h>
59 #include <fcntl.h>
60 #include <errno.h>
61 #include <string.h>
62 #include <sys/types.h>
63 #include <sys/stat.h>
64 #include <sys/param.h>
65 #include <libzonecfg.h>
66 
67 #define	PATH_MAPFILE	"tmp/.alt.lu-zone-map"
68 
69 static int
lock_op(int fd,int type)70 lock_op(int fd, int type)
71 {
72 	struct flock lock;
73 
74 	lock.l_type = type;
75 	lock.l_whence = SEEK_SET;
76 	lock.l_start = 0;
77 	lock.l_len = 0;
78 
79 	return (fcntl(fd, F_SETLKW, &lock));
80 }
81 
82 FILE *
zonecfg_open_scratch(const char * rootpath,boolean_t createfile)83 zonecfg_open_scratch(const char *rootpath, boolean_t createfile)
84 {
85 	mode_t oldmask = umask(0);
86 	struct stat lbuf, fbuf;
87 	int fd, flags;
88 	FILE *fp;
89 	char mapfile[MAXPATHLEN];
90 
91 	(void) snprintf(mapfile, sizeof (mapfile), "%s/" PATH_MAPFILE,
92 	    rootpath);
93 
94 	flags = O_RDWR | O_NOFOLLOW | O_NOLINKS;
95 	if (createfile)
96 		flags |= O_EXCL | O_CREAT;
97 	if ((fd = open(mapfile, flags, 0644)) == -1) {
98 		if (!createfile) {
99 			errno = ENOENT;
100 			goto failure;
101 		}
102 		if (lstat(mapfile, &lbuf) == -1)
103 			goto failure;
104 		if (!S_ISREG(lbuf.st_mode) || lbuf.st_nlink != 1 ||
105 		    lbuf.st_uid != 0) {
106 			errno = EINVAL;
107 			goto failure;
108 		}
109 		fd = open(mapfile, O_RDWR);
110 		if (fd == -1)
111 			goto failure;
112 		if (fstat(fd, &fbuf) == -1)
113 			goto failure;
114 		if (lbuf.st_ino != fbuf.st_ino || lbuf.st_dev != fbuf.st_dev) {
115 			errno = EINVAL;
116 			goto failure;
117 		}
118 	}
119 	if (lock_op(fd, F_RDLCK) == -1)
120 		goto failure;
121 	(void) umask(oldmask);
122 	if ((fp = fdopen(fd, "r+")) == NULL)
123 		(void) close(fd);
124 	return (fp);
125 
126 failure:
127 	if (fd != -1)
128 		(void) close(fd);
129 	(void) umask(oldmask);
130 	return (NULL);
131 }
132 
133 int
zonecfg_lock_scratch(FILE * fp)134 zonecfg_lock_scratch(FILE *fp)
135 {
136 	if (fflush(fp) != 0)
137 		return (-1);
138 	return (lock_op(fileno(fp), F_WRLCK));
139 }
140 
141 void
zonecfg_close_scratch(FILE * fp)142 zonecfg_close_scratch(FILE *fp)
143 {
144 	(void) fclose(fp);
145 }
146 
147 int
zonecfg_get_scratch(FILE * fp,char * zonename,size_t namelen,char * kernname,size_t kernlen,char * altroot,size_t altlen)148 zonecfg_get_scratch(FILE *fp, char *zonename, size_t namelen, char *kernname,
149     size_t kernlen, char *altroot, size_t altlen)
150 {
151 	char line[2 * ZONENAME_MAX + MAXPATHLEN + 2];
152 	char *cp, *cp2;
153 
154 	/* We always hold at least a read lock on the file */
155 	for (;;) {
156 		if (fgets(line, sizeof (line), fp) == NULL)
157 			return (-1);
158 		if ((cp = strchr(line, '\n')) == NULL)
159 			return (-1);
160 		*cp = '\0';
161 		if ((cp = strchr(line, ' ')) == NULL)
162 			cp = line + strlen(line);
163 		else
164 			*cp++ = '\0';
165 		if (zonename != NULL &&
166 		    strlcpy(zonename, line, namelen) >= namelen)
167 			continue;
168 		if ((cp2 = strchr(cp, ' ')) == NULL)
169 			cp2 = cp + strlen(cp);
170 		else
171 			*cp2++ = '\0';
172 		if (kernname != NULL &&
173 		    strlcpy(kernname, cp, kernlen) >= kernlen)
174 			continue;
175 		if (altroot != NULL && strlcpy(altroot, cp2, altlen) >= altlen)
176 			continue;
177 		break;
178 	}
179 	return (0);
180 }
181 
182 int
zonecfg_find_scratch(FILE * fp,const char * zonename,const char * altroot,char * kernzone,size_t kernlen)183 zonecfg_find_scratch(FILE *fp, const char *zonename, const char *altroot,
184     char *kernzone, size_t kernlen)
185 {
186 	char zone[ZONENAME_MAX];
187 	char aroot[MAXPATHLEN];
188 
189 	rewind(fp);
190 	while (zonecfg_get_scratch(fp, zone, sizeof (zone), kernzone, kernlen,
191 	    aroot, sizeof (aroot)) == 0) {
192 		if (strcmp(zone, zonename) == 0 && strcmp(altroot, aroot) == 0)
193 			return (0);
194 	}
195 	return (-1);
196 }
197 
198 int
zonecfg_reverse_scratch(FILE * fp,const char * kernzone,char * zonename,size_t namelen,char * altroot,size_t altlen)199 zonecfg_reverse_scratch(FILE *fp, const char *kernzone, char *zonename,
200     size_t namelen, char *altroot, size_t altlen)
201 {
202 	char kzone[ZONENAME_MAX];
203 
204 	rewind(fp);
205 	while (zonecfg_get_scratch(fp, zonename, namelen, kzone,
206 	    sizeof (kzone), altroot, altlen) == 0) {
207 		if (strcmp(kzone, kernzone) == 0)
208 			return (0);
209 	}
210 	return (-1);
211 }
212 
213 int
zonecfg_add_scratch(FILE * fp,const char * zonename,const char * kernzone,const char * altroot)214 zonecfg_add_scratch(FILE *fp, const char *zonename, const char *kernzone,
215     const char *altroot)
216 {
217 	if (fseek(fp, 0, SEEK_END) == -1)
218 		return (-1);
219 	if (fprintf(fp, "%s %s %s\n", zonename, kernzone, altroot) == EOF)
220 		return (-1);
221 	if (fflush(fp) != 0)
222 		return (-1);
223 	return (0);
224 }
225 
226 int
zonecfg_delete_scratch(FILE * fp,const char * kernzone)227 zonecfg_delete_scratch(FILE *fp, const char *kernzone)
228 {
229 	char zone[ZONENAME_MAX];
230 	char kzone[ZONENAME_MAX];
231 	char aroot[MAXPATHLEN];
232 	long roffs, woffs;
233 
234 	/*
235 	 * The implementation here is intentionally quite simple.  We could
236 	 * allocate a buffer that's big enough to hold the data up to
237 	 * stat.st_size and then write back out the part we need to, but there
238 	 * seems to be little point.
239 	 */
240 	rewind(fp);
241 	roffs = 0;
242 	do {
243 		woffs = roffs;
244 		if (zonecfg_get_scratch(fp, NULL, 0, kzone, sizeof (kzone),
245 		    NULL, 0) != 0)
246 			return (-1);
247 		roffs = ftell(fp);
248 	} while (strcmp(kzone, kernzone) != 0);
249 	while (zonecfg_get_scratch(fp, zone, sizeof (zone), kzone,
250 	    sizeof (kzone), aroot, sizeof aroot) == 0) {
251 		roffs = ftell(fp);
252 		if (fseek(fp, woffs, SEEK_SET) == -1)
253 			break;
254 		if (fprintf(fp, "%s %s %s\n", zone, kzone, aroot) == EOF)
255 			break;
256 		woffs = ftell(fp);
257 		if (fseek(fp, roffs, SEEK_SET) == -1)
258 			break;
259 	}
260 	(void) ftruncate(fileno(fp), woffs);
261 	return (0);
262 }
263 
264 boolean_t
zonecfg_is_scratch(const char * kernzone)265 zonecfg_is_scratch(const char *kernzone)
266 {
267 	return (strncmp(kernzone, "SUNWlu", 6) == 0);
268 }
269