1#include <stdio.h>
2#include <stdlib.h>
3#include <stddef.h>
4#include <stdarg.h>
5#include <unistd.h>
6#include <errno.h>
7#include <string.h>
8#include <fcntl.h>
9#include <sys/types.h>
10#include <sys/mman.h>
11#include <sys/statfs.h>
12#include "kern_util.h"
13#include "user.h"
14#include "mem_user.h"
15#include "init.h"
16#include "os.h"
17#include "tempfile.h"
18#include "kern_constants.h"
19
20#include <sys/param.h>
21
22/* Modified by which_tmpdir, which is called during early boot */
23static char *default_tmpdir = "/tmp";
24
25/*
26 *  Modified when creating the physical memory file and when checking
27 * the tmp filesystem for usability, both happening during early boot.
28 */
29static char *tempdir = NULL;
30
31static void __init find_tempdir(void)
32{
33	char *dirs[] = { "TMP", "TEMP", "TMPDIR", NULL };
34	int i;
35	char *dir = NULL;
36
37	if(tempdir != NULL) /* We've already been called */
38		return;
39	for(i = 0; dirs[i]; i++){
40		dir = getenv(dirs[i]);
41		if((dir != NULL) && (*dir != '\0'))
42			break;
43	}
44	if((dir == NULL) || (*dir == '\0'))
45		dir = default_tmpdir;
46
47	tempdir = malloc(strlen(dir) + 2);
48	if(tempdir == NULL){
49		fprintf(stderr, "Failed to malloc tempdir, "
50			"errno = %d\n", errno);
51		return;
52	}
53	strcpy(tempdir, dir);
54	strcat(tempdir, "/");
55}
56
57/* This will return 1, with the first character in buf being the
58 * character following the next instance of c in the file.  This will
59 * read the file as needed.  If there's an error, -errno is returned;
60 * if the end of the file is reached, 0 is returned.
61 */
62static int next(int fd, char *buf, int size, char c)
63{
64	int n, len;
65	char *ptr;
66
67	while((ptr = strchr(buf, c)) == NULL){
68		n = read(fd, buf, size - 1);
69		if(n == 0)
70			return 0;
71		else if(n < 0)
72			return -errno;
73
74		buf[n] = '\0';
75	}
76
77	ptr++;
78	len = strlen(ptr);
79	memmove(buf, ptr, len + 1);
80
81	/* Refill the buffer so that if there's a partial string that we care
82	 * about, it will be completed, and we can recognize it.
83	 */
84	n = read(fd, &buf[len], size - len - 1);
85	if(n < 0)
86		return -errno;
87
88	buf[len + n] = '\0';
89	return 1;
90}
91
92/* which_tmpdir is called only during early boot */
93static int checked_tmpdir = 0;
94
95/* Look for a tmpfs mounted at /dev/shm.  I couldn't find a cleaner
96 * way to do this than to parse /proc/mounts.  statfs will return the
97 * same filesystem magic number and fs id for both /dev and /dev/shm
98 * when they are both tmpfs, so you can't tell if they are different
99 * filesystems.  Also, there seems to be no other way of finding the
100 * mount point of a filesystem from within it.
101 *
102 * If a /dev/shm tmpfs entry is found, then we switch to using it.
103 * Otherwise, we stay with the default /tmp.
104 */
105static void which_tmpdir(void)
106{
107	int fd, found;
108	char buf[128] = { '\0' };
109
110	if(checked_tmpdir)
111		return;
112
113	checked_tmpdir = 1;
114
115	printf("Checking for tmpfs mount on /dev/shm...");
116
117	fd = open("/proc/mounts", O_RDONLY);
118	if(fd < 0){
119		printf("failed to open /proc/mounts, errno = %d\n", errno);
120		return;
121	}
122
123	while(1){
124		found = next(fd, buf, ARRAY_SIZE(buf), ' ');
125		if(found != 1)
126			break;
127
128		if(!strncmp(buf, "/dev/shm", strlen("/dev/shm")))
129			goto found;
130
131		found = next(fd, buf, ARRAY_SIZE(buf), '\n');
132		if(found != 1)
133			break;
134	}
135
136err:
137	if(found == 0)
138		printf("nothing mounted on /dev/shm\n");
139	else if(found < 0)
140		printf("read returned errno %d\n", -found);
141
142out:
143	close(fd);
144
145	return;
146
147found:
148	found = next(fd, buf, ARRAY_SIZE(buf), ' ');
149	if(found != 1)
150		goto err;
151
152	if(strncmp(buf, "tmpfs", strlen("tmpfs"))){
153		printf("not tmpfs\n");
154		goto out;
155	}
156
157	printf("OK\n");
158	default_tmpdir = "/dev/shm";
159	goto out;
160}
161
162/*
163 * This proc still used in tt-mode
164 * (file: kernel/tt/ptproxy/proxy.c, proc: start_debugger).
165 * So it isn't 'static' yet.
166 */
167int __init make_tempfile(const char *template, char **out_tempname,
168			 int do_unlink)
169{
170	char *tempname;
171	int fd;
172
173	which_tmpdir();
174	tempname = malloc(MAXPATHLEN);
175
176	find_tempdir();
177	if (template[0] != '/')
178		strcpy(tempname, tempdir);
179	else
180		tempname[0] = '\0';
181	strcat(tempname, template);
182	fd = mkstemp(tempname);
183	if(fd < 0){
184		fprintf(stderr, "open - cannot create %s: %s\n", tempname,
185			strerror(errno));
186		goto out;
187	}
188	if(do_unlink && (unlink(tempname) < 0)){
189		perror("unlink");
190		goto out;
191	}
192	if(out_tempname){
193		*out_tempname = tempname;
194	} else {
195		free(tempname);
196	}
197	return fd;
198out:
199	free(tempname);
200	return -1;
201}
202
203#define TEMPNAME_TEMPLATE "vm_file-XXXXXX"
204
205/*
206 * This proc is used in start_up.c
207 * So it isn't 'static'.
208 */
209int __init create_tmp_file(unsigned long long len)
210{
211	int fd, err;
212	char zero;
213
214	fd = make_tempfile(TEMPNAME_TEMPLATE, NULL, 1);
215	if(fd < 0) {
216		exit(1);
217	}
218
219	err = fchmod(fd, 0777);
220	if(err < 0){
221		perror("os_mode_fd");
222		exit(1);
223	}
224
225	/* Seek to len - 1 because writing a character there will
226	 * increase the file size by one byte, to the desired length.
227	 */
228	if (lseek64(fd, len - 1, SEEK_SET) < 0) {
229		perror("os_seek_file");
230		exit(1);
231	}
232
233	zero = 0;
234
235	err = write(fd, &zero, 1);
236	if(err != 1){
237		perror("write");
238		exit(1);
239	}
240
241	return fd;
242}
243
244int __init create_mem_file(unsigned long long len)
245{
246	int err, fd;
247
248	fd = create_tmp_file(len);
249
250	err = os_set_exec_close(fd, 1);
251	if(err < 0){
252		errno = -err;
253		perror("exec_close");
254	}
255	return fd;
256}
257
258
259void __init check_tmpexec(void)
260{
261	void *addr;
262	int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
263
264	addr = mmap(NULL, UM_KERN_PAGE_SIZE,
265		    PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
266	printf("Checking PROT_EXEC mmap in %s...",tempdir);
267	fflush(stdout);
268	if(addr == MAP_FAILED){
269		err = errno;
270		perror("failed");
271		if(err == EPERM)
272			printf("%s must be not mounted noexec\n",tempdir);
273		exit(1);
274	}
275	printf("OK\n");
276	munmap(addr, UM_KERN_PAGE_SIZE);
277
278	close(fd);
279}
280