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1/*
2 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
4 */
5
6#include <stdio.h>
7#include <stdlib.h>
8#include <dirent.h>
9#include <errno.h>
10#include <fcntl.h>
11#include <signal.h>
12#include <string.h>
13#include <unistd.h>
14#include <sys/stat.h>
15#include "init.h"
16#include "kern_constants.h"
17#include "os.h"
18#include "user.h"
19
20#define UML_DIR "~/.uml/"
21
22#define UMID_LEN 64
23
24/* Changed by set_umid, which is run early in boot */
25static char umid[UMID_LEN] = { 0 };
26
27/* Changed by set_uml_dir and make_uml_dir, which are run early in boot */
28static char *uml_dir = UML_DIR;
29
30static int __init make_uml_dir(void)
31{
32 char dir[512] = { '\0' };
33 int len, err;
34
35 if (*uml_dir == '~') {
36 char *home = getenv("HOME");
37
38 err = -ENOENT;
39 if (home == NULL) {
40 printk(UM_KERN_ERR "make_uml_dir : no value in "
41 "environment for $HOME\n");
42 goto err;
43 }
44 strlcpy(dir, home, sizeof(dir));
45 uml_dir++;
46 }
47 strlcat(dir, uml_dir, sizeof(dir));
48 len = strlen(dir);
49 if (len > 0 && dir[len - 1] != '/')
50 strlcat(dir, "/", sizeof(dir));
51
52 err = -ENOMEM;
53 uml_dir = malloc(strlen(dir) + 1);
54 if (uml_dir == NULL) {
55 printf("make_uml_dir : malloc failed, errno = %d\n", errno);
56 goto err;
57 }
58 strcpy(uml_dir, dir);
59
60 if ((mkdir(uml_dir, 0777) < 0) && (errno != EEXIST)) {
61 printf("Failed to mkdir '%s': %s\n", uml_dir, strerror(errno));
62 err = -errno;
63 goto err_free;
64 }
65 return 0;
66
67err_free:
68 free(uml_dir);
69err:
70 uml_dir = NULL;
71 return err;
72}
73
74/*
75 * Unlinks the files contained in @dir and then removes @dir.
76 * Doesn't handle directory trees, so it's not like rm -rf, but almost such. We
77 * ignore ENOENT errors for anything (they happen, strangely enough - possibly
78 * due to races between multiple dying UML threads).
79 */
80static int remove_files_and_dir(char *dir)
81{
82 DIR *directory;
83 struct dirent *ent;
84 int len;
85 char file[256];
86 int ret;
87
88 directory = opendir(dir);
89 if (directory == NULL) {
90 if (errno != ENOENT)
91 return -errno;
92 else
93 return 0;
94 }
95
96 while ((ent = readdir(directory)) != NULL) {
97 if (!strcmp(ent->d_name, ".") || !strcmp(ent->d_name, ".."))
98 continue;
99 len = strlen(dir) + sizeof("/") + strlen(ent->d_name) + 1;
100 if (len > sizeof(file)) {
101 ret = -E2BIG;
102 goto out;
103 }
104
105 sprintf(file, "%s/%s", dir, ent->d_name);
106 if (unlink(file) < 0 && errno != ENOENT) {
107 ret = -errno;
108 goto out;
109 }
110 }
111
112 if (rmdir(dir) < 0 && errno != ENOENT) {
113 ret = -errno;
114 goto out;
115 }
116
117 ret = 0;
118out:
119 closedir(directory);
120 return ret;
121}
122
123/*
124 * This says that there isn't already a user of the specified directory even if
125 * there are errors during the checking. This is because if these errors
126 * happen, the directory is unusable by the pre-existing UML, so we might as
127 * well take it over. This could happen either by
128 * the existing UML somehow corrupting its umid directory
129 * something other than UML sticking stuff in the directory
130 * this boot racing with a shutdown of the other UML
131 * In any of these cases, the directory isn't useful for anything else.
132 *
133 * Boolean return: 1 if in use, 0 otherwise.
134 */
135static inline int is_umdir_used(char *dir)
136{
137 char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
138 char pid[sizeof("nnnnn\0")], *end;
139 int dead, fd, p, n, err;
140
141 n = snprintf(file, sizeof(file), "%s/pid", dir);
142 if (n >= sizeof(file)) {
143 printk(UM_KERN_ERR "is_umdir_used - pid filename too long\n");
144 err = -E2BIG;
145 goto out;
146 }
147
148 dead = 0;
149 fd = open(file, O_RDONLY);
150 if (fd < 0) {
151 fd = -errno;
152 if (fd != -ENOENT) {
153 printk(UM_KERN_ERR "is_umdir_used : couldn't open pid "
154 "file '%s', err = %d\n", file, -fd);
155 }
156 goto out;
157 }
158
159 err = 0;
160 n = read(fd, pid, sizeof(pid));
161 if (n < 0) {
162 printk(UM_KERN_ERR "is_umdir_used : couldn't read pid file "
163 "'%s', err = %d\n", file, errno);
164 goto out_close;
165 } else if (n == 0) {
166 printk(UM_KERN_ERR "is_umdir_used : couldn't read pid file "
167 "'%s', 0-byte read\n", file);
168 goto out_close;
169 }
170
171 p = strtoul(pid, &end, 0);
172 if (end == pid) {
173 printk(UM_KERN_ERR "is_umdir_used : couldn't parse pid file "
174 "'%s', errno = %d\n", file, errno);
175 goto out_close;
176 }
177
178 if ((kill(p, 0) == 0) || (errno != ESRCH)) {
179 printk(UM_KERN_ERR "umid \"%s\" is already in use by pid %d\n",
180 umid, p);
181 return 1;
182 }
183
184out_close:
185 close(fd);
186out:
187 return 0;
188}
189
190/*
191 * Try to remove the directory @dir unless it's in use.
192 * Precondition: @dir exists.
193 * Returns 0 for success, < 0 for failure in removal or if the directory is in
194 * use.
195 */
196static int umdir_take_if_dead(char *dir)
197{
198 int ret;
199 if (is_umdir_used(dir))
200 return -EEXIST;
201
202 ret = remove_files_and_dir(dir);
203 if (ret) {
204 printk(UM_KERN_ERR "is_umdir_used - remove_files_and_dir "
205 "failed with err = %d\n", ret);
206 }
207 return ret;
208}
209
210static void __init create_pid_file(void)
211{
212 char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
213 char pid[sizeof("nnnnn\0")];
214 int fd, n;
215
216 if (umid_file_name("pid", file, sizeof(file)))
217 return;
218
219 fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0644);
220 if (fd < 0) {
221 printk(UM_KERN_ERR "Open of machine pid file \"%s\" failed: "
222 "%s\n", file, strerror(errno));
223 return;
224 }
225
226 snprintf(pid, sizeof(pid), "%d\n", getpid());
227 n = write(fd, pid, strlen(pid));
228 if (n != strlen(pid))
229 printk(UM_KERN_ERR "Write of pid file failed - err = %d\n",
230 errno);
231
232 close(fd);
233}
234
235int __init set_umid(char *name)
236{
237 if (strlen(name) > UMID_LEN - 1)
238 return -E2BIG;
239
240 strlcpy(umid, name, sizeof(umid));
241
242 return 0;
243}
244
245/* Changed in make_umid, which is called during early boot */
246static int umid_setup = 0;
247
248static int __init make_umid(void)
249{
250 int fd, err;
251 char tmp[256];
252
253 if (umid_setup)
254 return 0;
255
256 make_uml_dir();
257
258 if (*umid == '\0') {
259 strlcpy(tmp, uml_dir, sizeof(tmp));
260 strlcat(tmp, "XXXXXX", sizeof(tmp));
261 fd = mkstemp(tmp);
262 if (fd < 0) {
263 printk(UM_KERN_ERR "make_umid - mkstemp(%s) failed: "
264 "%s\n", tmp, strerror(errno));
265 err = -errno;
266 goto err;
267 }
268
269 close(fd);
270
271 set_umid(&tmp[strlen(uml_dir)]);
272
273 /*
274 * There's a nice tiny little race between this unlink and
275 * the mkdir below. It'd be nice if there were a mkstemp
276 * for directories.
277 */
278 if (unlink(tmp)) {
279 err = -errno;
280 goto err;
281 }
282 }
283
284 snprintf(tmp, sizeof(tmp), "%s%s", uml_dir, umid);
285 err = mkdir(tmp, 0777);
286 if (err < 0) {
287 err = -errno;
288 if (err != -EEXIST)
289 goto err;
290
291 if (umdir_take_if_dead(tmp) < 0)
292 goto err;
293
294 err = mkdir(tmp, 0777);
295 }
296 if (err) {
297 err = -errno;
298 printk(UM_KERN_ERR "Failed to create '%s' - err = %d\n", umid,
299 errno);
300 goto err;
301 }
302
303 umid_setup = 1;
304
305 create_pid_file();
306
307 err = 0;
308 err:
309 return err;
310}
311
312static int __init make_umid_init(void)
313{
314 if (!make_umid())
315 return 0;
316
317 /*
318 * If initializing with the given umid failed, then try again with
319 * a random one.
320 */
321 printk(UM_KERN_ERR "Failed to initialize umid \"%s\", trying with a "
322 "random umid\n", umid);
323 *umid = '\0';
324 make_umid();
325
326 return 0;
327}
328
329__initcall(make_umid_init);
330
331int __init umid_file_name(char *name, char *buf, int len)
332{
333 int n, err;
334
335 err = make_umid();
336 if (err)
337 return err;
338
339 n = snprintf(buf, len, "%s%s/%s", uml_dir, umid, name);
340 if (n >= len) {
341 printk(UM_KERN_ERR "umid_file_name : buffer too short\n");
342 return -E2BIG;
343 }
344
345 return 0;
346}
347
348char *get_umid(void)
349{
350 return umid;
351}
352
353static int __init set_uml_dir(char *name, int *add)
354{
355 if (*name == '\0') {
356 printf("uml_dir can't be an empty string\n");
357 return 0;
358 }
359
360 if (name[strlen(name) - 1] == '/') {
361 uml_dir = name;
362 return 0;
363 }
364
365 uml_dir = malloc(strlen(name) + 2);
366 if (uml_dir == NULL) {
367 printf("Failed to malloc uml_dir - error = %d\n", errno);
368
369 /*
370 * Return 0 here because do_initcalls doesn't look at
371 * the return value.
372 */
373 return 0;
374 }
375 sprintf(uml_dir, "%s/", name);
376
377 return 0;
378}
379
380__uml_setup("uml_dir=", set_uml_dir,
381"uml_dir=<directory>\n"
382" The location to place the pid and umid files.\n\n"
383);
384
385static void remove_umid_dir(void)
386{
387 char dir[strlen(uml_dir) + UMID_LEN + 1], err;
388
389 sprintf(dir, "%s%s", uml_dir, umid);
390 err = remove_files_and_dir(dir);
391 if (err)
392 printf("remove_umid_dir - remove_files_and_dir failed with "
393 "err = %d\n", err);
394}
395
396__uml_exitcall(remove_umid_dir);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 */
5
6#include <stdio.h>
7#include <stdlib.h>
8#include <dirent.h>
9#include <errno.h>
10#include <fcntl.h>
11#include <signal.h>
12#include <string.h>
13#include <unistd.h>
14#include <sys/stat.h>
15#include <init.h>
16#include <os.h>
17
18#define UML_DIR "~/.uml/"
19
20#define UMID_LEN 64
21
22/* Changed by set_umid, which is run early in boot */
23static char umid[UMID_LEN] = { 0 };
24
25/* Changed by set_uml_dir and make_uml_dir, which are run early in boot */
26static char *uml_dir = UML_DIR;
27
28static int __init make_uml_dir(void)
29{
30 char dir[512] = { '\0' };
31 int len, err;
32
33 if (*uml_dir == '~') {
34 char *home = getenv("HOME");
35
36 err = -ENOENT;
37 if (home == NULL) {
38 printk(UM_KERN_ERR
39 "%s: no value in environment for $HOME\n",
40 __func__);
41 goto err;
42 }
43 strlcpy(dir, home, sizeof(dir));
44 uml_dir++;
45 }
46 strlcat(dir, uml_dir, sizeof(dir));
47 len = strlen(dir);
48 if (len > 0 && dir[len - 1] != '/')
49 strlcat(dir, "/", sizeof(dir));
50
51 err = -ENOMEM;
52 uml_dir = malloc(strlen(dir) + 1);
53 if (uml_dir == NULL) {
54 printk(UM_KERN_ERR "%s : malloc failed, errno = %d\n",
55 __func__, errno);
56 goto err;
57 }
58 strcpy(uml_dir, dir);
59
60 if ((mkdir(uml_dir, 0777) < 0) && (errno != EEXIST)) {
61 printk(UM_KERN_ERR "Failed to mkdir '%s': %s\n",
62 uml_dir, strerror(errno));
63 err = -errno;
64 goto err_free;
65 }
66 return 0;
67
68err_free:
69 free(uml_dir);
70err:
71 uml_dir = NULL;
72 return err;
73}
74
75/*
76 * Unlinks the files contained in @dir and then removes @dir.
77 * Doesn't handle directory trees, so it's not like rm -rf, but almost such. We
78 * ignore ENOENT errors for anything (they happen, strangely enough - possibly
79 * due to races between multiple dying UML threads).
80 */
81static int remove_files_and_dir(char *dir)
82{
83 DIR *directory;
84 struct dirent *ent;
85 int len;
86 char file[256];
87 int ret;
88
89 directory = opendir(dir);
90 if (directory == NULL) {
91 if (errno != ENOENT)
92 return -errno;
93 else
94 return 0;
95 }
96
97 while ((ent = readdir(directory)) != NULL) {
98 if (!strcmp(ent->d_name, ".") || !strcmp(ent->d_name, ".."))
99 continue;
100 len = strlen(dir) + sizeof("/") + strlen(ent->d_name) + 1;
101 if (len > sizeof(file)) {
102 ret = -E2BIG;
103 goto out;
104 }
105
106 sprintf(file, "%s/%s", dir, ent->d_name);
107 if (unlink(file) < 0 && errno != ENOENT) {
108 ret = -errno;
109 goto out;
110 }
111 }
112
113 if (rmdir(dir) < 0 && errno != ENOENT) {
114 ret = -errno;
115 goto out;
116 }
117
118 ret = 0;
119out:
120 closedir(directory);
121 return ret;
122}
123
124/*
125 * This says that there isn't already a user of the specified directory even if
126 * there are errors during the checking. This is because if these errors
127 * happen, the directory is unusable by the pre-existing UML, so we might as
128 * well take it over. This could happen either by
129 * the existing UML somehow corrupting its umid directory
130 * something other than UML sticking stuff in the directory
131 * this boot racing with a shutdown of the other UML
132 * In any of these cases, the directory isn't useful for anything else.
133 *
134 * Boolean return: 1 if in use, 0 otherwise.
135 */
136static inline int is_umdir_used(char *dir)
137{
138 char pid[sizeof("nnnnn\0")], *end, *file;
139 int dead, fd, p, n, err;
140 size_t filelen;
141
142 err = asprintf(&file, "%s/pid", dir);
143 if (err < 0)
144 return 0;
145
146 filelen = strlen(file);
147
148 n = snprintf(file, filelen, "%s/pid", dir);
149 if (n >= filelen) {
150 printk(UM_KERN_ERR "is_umdir_used - pid filename too long\n");
151 err = -E2BIG;
152 goto out;
153 }
154
155 dead = 0;
156 fd = open(file, O_RDONLY);
157 if (fd < 0) {
158 fd = -errno;
159 if (fd != -ENOENT) {
160 printk(UM_KERN_ERR "is_umdir_used : couldn't open pid "
161 "file '%s', err = %d\n", file, -fd);
162 }
163 goto out;
164 }
165
166 err = 0;
167 n = read(fd, pid, sizeof(pid));
168 if (n < 0) {
169 printk(UM_KERN_ERR "is_umdir_used : couldn't read pid file "
170 "'%s', err = %d\n", file, errno);
171 goto out_close;
172 } else if (n == 0) {
173 printk(UM_KERN_ERR "is_umdir_used : couldn't read pid file "
174 "'%s', 0-byte read\n", file);
175 goto out_close;
176 }
177
178 p = strtoul(pid, &end, 0);
179 if (end == pid) {
180 printk(UM_KERN_ERR "is_umdir_used : couldn't parse pid file "
181 "'%s', errno = %d\n", file, errno);
182 goto out_close;
183 }
184
185 if ((kill(p, 0) == 0) || (errno != ESRCH)) {
186 printk(UM_KERN_ERR "umid \"%s\" is already in use by pid %d\n",
187 umid, p);
188 return 1;
189 }
190
191out_close:
192 close(fd);
193out:
194 free(file);
195 return 0;
196}
197
198/*
199 * Try to remove the directory @dir unless it's in use.
200 * Precondition: @dir exists.
201 * Returns 0 for success, < 0 for failure in removal or if the directory is in
202 * use.
203 */
204static int umdir_take_if_dead(char *dir)
205{
206 int ret;
207 if (is_umdir_used(dir))
208 return -EEXIST;
209
210 ret = remove_files_and_dir(dir);
211 if (ret) {
212 printk(UM_KERN_ERR "is_umdir_used - remove_files_and_dir "
213 "failed with err = %d\n", ret);
214 }
215 return ret;
216}
217
218static void __init create_pid_file(void)
219{
220 char pid[sizeof("nnnnn\0")], *file;
221 int fd, n;
222
223 file = malloc(strlen(uml_dir) + UMID_LEN + sizeof("/pid\0"));
224 if (!file)
225 return;
226
227 if (umid_file_name("pid", file, sizeof(file)))
228 goto out;
229
230 fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0644);
231 if (fd < 0) {
232 printk(UM_KERN_ERR "Open of machine pid file \"%s\" failed: "
233 "%s\n", file, strerror(errno));
234 goto out;
235 }
236
237 snprintf(pid, sizeof(pid), "%d\n", getpid());
238 n = write(fd, pid, strlen(pid));
239 if (n != strlen(pid))
240 printk(UM_KERN_ERR "Write of pid file failed - err = %d\n",
241 errno);
242
243 close(fd);
244out:
245 free(file);
246}
247
248int __init set_umid(char *name)
249{
250 if (strlen(name) > UMID_LEN - 1)
251 return -E2BIG;
252
253 strlcpy(umid, name, sizeof(umid));
254
255 return 0;
256}
257
258/* Changed in make_umid, which is called during early boot */
259static int umid_setup = 0;
260
261static int __init make_umid(void)
262{
263 int fd, err;
264 char tmp[256];
265
266 if (umid_setup)
267 return 0;
268
269 make_uml_dir();
270
271 if (*umid == '\0') {
272 strlcpy(tmp, uml_dir, sizeof(tmp));
273 strlcat(tmp, "XXXXXX", sizeof(tmp));
274 fd = mkstemp(tmp);
275 if (fd < 0) {
276 printk(UM_KERN_ERR "make_umid - mkstemp(%s) failed: "
277 "%s\n", tmp, strerror(errno));
278 err = -errno;
279 goto err;
280 }
281
282 close(fd);
283
284 set_umid(&tmp[strlen(uml_dir)]);
285
286 /*
287 * There's a nice tiny little race between this unlink and
288 * the mkdir below. It'd be nice if there were a mkstemp
289 * for directories.
290 */
291 if (unlink(tmp)) {
292 err = -errno;
293 goto err;
294 }
295 }
296
297 snprintf(tmp, sizeof(tmp), "%s%s", uml_dir, umid);
298 err = mkdir(tmp, 0777);
299 if (err < 0) {
300 err = -errno;
301 if (err != -EEXIST)
302 goto err;
303
304 if (umdir_take_if_dead(tmp) < 0)
305 goto err;
306
307 err = mkdir(tmp, 0777);
308 }
309 if (err) {
310 err = -errno;
311 printk(UM_KERN_ERR "Failed to create '%s' - err = %d\n", umid,
312 errno);
313 goto err;
314 }
315
316 umid_setup = 1;
317
318 create_pid_file();
319
320 err = 0;
321 err:
322 return err;
323}
324
325static int __init make_umid_init(void)
326{
327 if (!make_umid())
328 return 0;
329
330 /*
331 * If initializing with the given umid failed, then try again with
332 * a random one.
333 */
334 printk(UM_KERN_ERR "Failed to initialize umid \"%s\", trying with a "
335 "random umid\n", umid);
336 *umid = '\0';
337 make_umid();
338
339 return 0;
340}
341
342__initcall(make_umid_init);
343
344int __init umid_file_name(char *name, char *buf, int len)
345{
346 int n, err;
347
348 err = make_umid();
349 if (err)
350 return err;
351
352 n = snprintf(buf, len, "%s%s/%s", uml_dir, umid, name);
353 if (n >= len) {
354 printk(UM_KERN_ERR "umid_file_name : buffer too short\n");
355 return -E2BIG;
356 }
357
358 return 0;
359}
360
361char *get_umid(void)
362{
363 return umid;
364}
365
366static int __init set_uml_dir(char *name, int *add)
367{
368 if (*name == '\0') {
369 os_warn("uml_dir can't be an empty string\n");
370 return 0;
371 }
372
373 if (name[strlen(name) - 1] == '/') {
374 uml_dir = name;
375 return 0;
376 }
377
378 uml_dir = malloc(strlen(name) + 2);
379 if (uml_dir == NULL) {
380 os_warn("Failed to malloc uml_dir - error = %d\n", errno);
381
382 /*
383 * Return 0 here because do_initcalls doesn't look at
384 * the return value.
385 */
386 return 0;
387 }
388 sprintf(uml_dir, "%s/", name);
389
390 return 0;
391}
392
393__uml_setup("uml_dir=", set_uml_dir,
394"uml_dir=<directory>\n"
395" The location to place the pid and umid files.\n\n"
396);
397
398static void remove_umid_dir(void)
399{
400 char *dir, err;
401
402 dir = malloc(strlen(uml_dir) + UMID_LEN + 1);
403 if (!dir)
404 return;
405
406 sprintf(dir, "%s%s", uml_dir, umid);
407 err = remove_files_and_dir(dir);
408 if (err)
409 os_warn("%s - remove_files_and_dir failed with err = %d\n",
410 __func__, err);
411
412 free(dir);
413}
414
415__uml_exitcall(remove_umid_dir);