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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 <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 "make_uml_dir : no value in "
39 "environment for $HOME\n");
40 goto err;
41 }
42 strlcpy(dir, home, sizeof(dir));
43 uml_dir++;
44 }
45 strlcat(dir, uml_dir, sizeof(dir));
46 len = strlen(dir);
47 if (len > 0 && dir[len - 1] != '/')
48 strlcat(dir, "/", sizeof(dir));
49
50 err = -ENOMEM;
51 uml_dir = malloc(strlen(dir) + 1);
52 if (uml_dir == NULL) {
53 printf("make_uml_dir : malloc failed, errno = %d\n", errno);
54 goto err;
55 }
56 strcpy(uml_dir, dir);
57
58 if ((mkdir(uml_dir, 0777) < 0) && (errno != EEXIST)) {
59 printf("Failed to mkdir '%s': %s\n", uml_dir, strerror(errno));
60 err = -errno;
61 goto err_free;
62 }
63 return 0;
64
65err_free:
66 free(uml_dir);
67err:
68 uml_dir = NULL;
69 return err;
70}
71
72/*
73 * Unlinks the files contained in @dir and then removes @dir.
74 * Doesn't handle directory trees, so it's not like rm -rf, but almost such. We
75 * ignore ENOENT errors for anything (they happen, strangely enough - possibly
76 * due to races between multiple dying UML threads).
77 */
78static int remove_files_and_dir(char *dir)
79{
80 DIR *directory;
81 struct dirent *ent;
82 int len;
83 char file[256];
84 int ret;
85
86 directory = opendir(dir);
87 if (directory == NULL) {
88 if (errno != ENOENT)
89 return -errno;
90 else
91 return 0;
92 }
93
94 while ((ent = readdir(directory)) != NULL) {
95 if (!strcmp(ent->d_name, ".") || !strcmp(ent->d_name, ".."))
96 continue;
97 len = strlen(dir) + sizeof("/") + strlen(ent->d_name) + 1;
98 if (len > sizeof(file)) {
99 ret = -E2BIG;
100 goto out;
101 }
102
103 sprintf(file, "%s/%s", dir, ent->d_name);
104 if (unlink(file) < 0 && errno != ENOENT) {
105 ret = -errno;
106 goto out;
107 }
108 }
109
110 if (rmdir(dir) < 0 && errno != ENOENT) {
111 ret = -errno;
112 goto out;
113 }
114
115 ret = 0;
116out:
117 closedir(directory);
118 return ret;
119}
120
121/*
122 * This says that there isn't already a user of the specified directory even if
123 * there are errors during the checking. This is because if these errors
124 * happen, the directory is unusable by the pre-existing UML, so we might as
125 * well take it over. This could happen either by
126 * the existing UML somehow corrupting its umid directory
127 * something other than UML sticking stuff in the directory
128 * this boot racing with a shutdown of the other UML
129 * In any of these cases, the directory isn't useful for anything else.
130 *
131 * Boolean return: 1 if in use, 0 otherwise.
132 */
133static inline int is_umdir_used(char *dir)
134{
135 char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
136 char pid[sizeof("nnnnn\0")], *end;
137 int dead, fd, p, n, err;
138
139 n = snprintf(file, sizeof(file), "%s/pid", dir);
140 if (n >= sizeof(file)) {
141 printk(UM_KERN_ERR "is_umdir_used - pid filename too long\n");
142 err = -E2BIG;
143 goto out;
144 }
145
146 dead = 0;
147 fd = open(file, O_RDONLY);
148 if (fd < 0) {
149 fd = -errno;
150 if (fd != -ENOENT) {
151 printk(UM_KERN_ERR "is_umdir_used : couldn't open pid "
152 "file '%s', err = %d\n", file, -fd);
153 }
154 goto out;
155 }
156
157 err = 0;
158 n = read(fd, pid, sizeof(pid));
159 if (n < 0) {
160 printk(UM_KERN_ERR "is_umdir_used : couldn't read pid file "
161 "'%s', err = %d\n", file, errno);
162 goto out_close;
163 } else if (n == 0) {
164 printk(UM_KERN_ERR "is_umdir_used : couldn't read pid file "
165 "'%s', 0-byte read\n", file);
166 goto out_close;
167 }
168
169 p = strtoul(pid, &end, 0);
170 if (end == pid) {
171 printk(UM_KERN_ERR "is_umdir_used : couldn't parse pid file "
172 "'%s', errno = %d\n", file, errno);
173 goto out_close;
174 }
175
176 if ((kill(p, 0) == 0) || (errno != ESRCH)) {
177 printk(UM_KERN_ERR "umid \"%s\" is already in use by pid %d\n",
178 umid, p);
179 return 1;
180 }
181
182out_close:
183 close(fd);
184out:
185 return 0;
186}
187
188/*
189 * Try to remove the directory @dir unless it's in use.
190 * Precondition: @dir exists.
191 * Returns 0 for success, < 0 for failure in removal or if the directory is in
192 * use.
193 */
194static int umdir_take_if_dead(char *dir)
195{
196 int ret;
197 if (is_umdir_used(dir))
198 return -EEXIST;
199
200 ret = remove_files_and_dir(dir);
201 if (ret) {
202 printk(UM_KERN_ERR "is_umdir_used - remove_files_and_dir "
203 "failed with err = %d\n", ret);
204 }
205 return ret;
206}
207
208static void __init create_pid_file(void)
209{
210 char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
211 char pid[sizeof("nnnnn\0")];
212 int fd, n;
213
214 if (umid_file_name("pid", file, sizeof(file)))
215 return;
216
217 fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0644);
218 if (fd < 0) {
219 printk(UM_KERN_ERR "Open of machine pid file \"%s\" failed: "
220 "%s\n", file, strerror(errno));
221 return;
222 }
223
224 snprintf(pid, sizeof(pid), "%d\n", getpid());
225 n = write(fd, pid, strlen(pid));
226 if (n != strlen(pid))
227 printk(UM_KERN_ERR "Write of pid file failed - err = %d\n",
228 errno);
229
230 close(fd);
231}
232
233int __init set_umid(char *name)
234{
235 if (strlen(name) > UMID_LEN - 1)
236 return -E2BIG;
237
238 strlcpy(umid, name, sizeof(umid));
239
240 return 0;
241}
242
243/* Changed in make_umid, which is called during early boot */
244static int umid_setup = 0;
245
246static int __init make_umid(void)
247{
248 int fd, err;
249 char tmp[256];
250
251 if (umid_setup)
252 return 0;
253
254 make_uml_dir();
255
256 if (*umid == '\0') {
257 strlcpy(tmp, uml_dir, sizeof(tmp));
258 strlcat(tmp, "XXXXXX", sizeof(tmp));
259 fd = mkstemp(tmp);
260 if (fd < 0) {
261 printk(UM_KERN_ERR "make_umid - mkstemp(%s) failed: "
262 "%s\n", tmp, strerror(errno));
263 err = -errno;
264 goto err;
265 }
266
267 close(fd);
268
269 set_umid(&tmp[strlen(uml_dir)]);
270
271 /*
272 * There's a nice tiny little race between this unlink and
273 * the mkdir below. It'd be nice if there were a mkstemp
274 * for directories.
275 */
276 if (unlink(tmp)) {
277 err = -errno;
278 goto err;
279 }
280 }
281
282 snprintf(tmp, sizeof(tmp), "%s%s", uml_dir, umid);
283 err = mkdir(tmp, 0777);
284 if (err < 0) {
285 err = -errno;
286 if (err != -EEXIST)
287 goto err;
288
289 if (umdir_take_if_dead(tmp) < 0)
290 goto err;
291
292 err = mkdir(tmp, 0777);
293 }
294 if (err) {
295 err = -errno;
296 printk(UM_KERN_ERR "Failed to create '%s' - err = %d\n", umid,
297 errno);
298 goto err;
299 }
300
301 umid_setup = 1;
302
303 create_pid_file();
304
305 err = 0;
306 err:
307 return err;
308}
309
310static int __init make_umid_init(void)
311{
312 if (!make_umid())
313 return 0;
314
315 /*
316 * If initializing with the given umid failed, then try again with
317 * a random one.
318 */
319 printk(UM_KERN_ERR "Failed to initialize umid \"%s\", trying with a "
320 "random umid\n", umid);
321 *umid = '\0';
322 make_umid();
323
324 return 0;
325}
326
327__initcall(make_umid_init);
328
329int __init umid_file_name(char *name, char *buf, int len)
330{
331 int n, err;
332
333 err = make_umid();
334 if (err)
335 return err;
336
337 n = snprintf(buf, len, "%s%s/%s", uml_dir, umid, name);
338 if (n >= len) {
339 printk(UM_KERN_ERR "umid_file_name : buffer too short\n");
340 return -E2BIG;
341 }
342
343 return 0;
344}
345
346char *get_umid(void)
347{
348 return umid;
349}
350
351static int __init set_uml_dir(char *name, int *add)
352{
353 if (*name == '\0') {
354 printf("uml_dir can't be an empty string\n");
355 return 0;
356 }
357
358 if (name[strlen(name) - 1] == '/') {
359 uml_dir = name;
360 return 0;
361 }
362
363 uml_dir = malloc(strlen(name) + 2);
364 if (uml_dir == NULL) {
365 printf("Failed to malloc uml_dir - error = %d\n", errno);
366
367 /*
368 * Return 0 here because do_initcalls doesn't look at
369 * the return value.
370 */
371 return 0;
372 }
373 sprintf(uml_dir, "%s/", name);
374
375 return 0;
376}
377
378__uml_setup("uml_dir=", set_uml_dir,
379"uml_dir=<directory>\n"
380" The location to place the pid and umid files.\n\n"
381);
382
383static void remove_umid_dir(void)
384{
385 char dir[strlen(uml_dir) + UMID_LEN + 1], err;
386
387 sprintf(dir, "%s%s", uml_dir, umid);
388 err = remove_files_and_dir(dir);
389 if (err)
390 printf("remove_umid_dir - remove_files_and_dir failed with "
391 "err = %d\n", err);
392}
393
394__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 n = strlen(uml_dir) + UMID_LEN + sizeof("/pid\0");
224 file = malloc(n);
225 if (!file)
226 return;
227
228 if (umid_file_name("pid", file, n))
229 goto out;
230
231 fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0644);
232 if (fd < 0) {
233 printk(UM_KERN_ERR "Open of machine pid file \"%s\" failed: "
234 "%s\n", file, strerror(errno));
235 goto out;
236 }
237
238 snprintf(pid, sizeof(pid), "%d\n", getpid());
239 n = write(fd, pid, strlen(pid));
240 if (n != strlen(pid))
241 printk(UM_KERN_ERR "Write of pid file failed - err = %d\n",
242 errno);
243
244 close(fd);
245out:
246 free(file);
247}
248
249int __init set_umid(char *name)
250{
251 if (strlen(name) > UMID_LEN - 1)
252 return -E2BIG;
253
254 strlcpy(umid, name, sizeof(umid));
255
256 return 0;
257}
258
259/* Changed in make_umid, which is called during early boot */
260static int umid_setup = 0;
261
262static int __init make_umid(void)
263{
264 int fd, err;
265 char tmp[256];
266
267 if (umid_setup)
268 return 0;
269
270 make_uml_dir();
271
272 if (*umid == '\0') {
273 strlcpy(tmp, uml_dir, sizeof(tmp));
274 strlcat(tmp, "XXXXXX", sizeof(tmp));
275 fd = mkstemp(tmp);
276 if (fd < 0) {
277 printk(UM_KERN_ERR "make_umid - mkstemp(%s) failed: "
278 "%s\n", tmp, strerror(errno));
279 err = -errno;
280 goto err;
281 }
282
283 close(fd);
284
285 set_umid(&tmp[strlen(uml_dir)]);
286
287 /*
288 * There's a nice tiny little race between this unlink and
289 * the mkdir below. It'd be nice if there were a mkstemp
290 * for directories.
291 */
292 if (unlink(tmp)) {
293 err = -errno;
294 goto err;
295 }
296 }
297
298 snprintf(tmp, sizeof(tmp), "%s%s", uml_dir, umid);
299 err = mkdir(tmp, 0777);
300 if (err < 0) {
301 err = -errno;
302 if (err != -EEXIST)
303 goto err;
304
305 if (umdir_take_if_dead(tmp) < 0)
306 goto err;
307
308 err = mkdir(tmp, 0777);
309 }
310 if (err) {
311 err = -errno;
312 printk(UM_KERN_ERR "Failed to create '%s' - err = %d\n", umid,
313 errno);
314 goto err;
315 }
316
317 umid_setup = 1;
318
319 create_pid_file();
320
321 err = 0;
322 err:
323 return err;
324}
325
326static int __init make_umid_init(void)
327{
328 if (!make_umid())
329 return 0;
330
331 /*
332 * If initializing with the given umid failed, then try again with
333 * a random one.
334 */
335 printk(UM_KERN_ERR "Failed to initialize umid \"%s\", trying with a "
336 "random umid\n", umid);
337 *umid = '\0';
338 make_umid();
339
340 return 0;
341}
342
343__initcall(make_umid_init);
344
345int __init umid_file_name(char *name, char *buf, int len)
346{
347 int n, err;
348
349 err = make_umid();
350 if (err)
351 return err;
352
353 n = snprintf(buf, len, "%s%s/%s", uml_dir, umid, name);
354 if (n >= len) {
355 printk(UM_KERN_ERR "umid_file_name : buffer too short\n");
356 return -E2BIG;
357 }
358
359 return 0;
360}
361
362char *get_umid(void)
363{
364 return umid;
365}
366
367static int __init set_uml_dir(char *name, int *add)
368{
369 if (*name == '\0') {
370 os_warn("uml_dir can't be an empty string\n");
371 return 0;
372 }
373
374 if (name[strlen(name) - 1] == '/') {
375 uml_dir = name;
376 return 0;
377 }
378
379 uml_dir = malloc(strlen(name) + 2);
380 if (uml_dir == NULL) {
381 os_warn("Failed to malloc uml_dir - error = %d\n", errno);
382
383 /*
384 * Return 0 here because do_initcalls doesn't look at
385 * the return value.
386 */
387 return 0;
388 }
389 sprintf(uml_dir, "%s/", name);
390
391 return 0;
392}
393
394__uml_setup("uml_dir=", set_uml_dir,
395"uml_dir=<directory>\n"
396" The location to place the pid and umid files.\n\n"
397);
398
399static void remove_umid_dir(void)
400{
401 char *dir, err;
402
403 dir = malloc(strlen(uml_dir) + UMID_LEN + 1);
404 if (!dir)
405 return;
406
407 sprintf(dir, "%s%s", uml_dir, umid);
408 err = remove_files_and_dir(dir);
409 if (err)
410 os_warn("%s - remove_files_and_dir failed with err = %d\n",
411 __func__, err);
412
413 free(dir);
414}
415
416__uml_exitcall(remove_umid_dir);