1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
|
/*
* Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/vfs.h>
#include <linux/magic.h>
#include <init.h>
#include <os.h>
/* Set by make_tempfile() during early boot. */
static char *tempdir = NULL;
/* Check if dir is on tmpfs. Return 0 if yes, -1 if no or error. */
static int __init check_tmpfs(const char *dir)
{
struct statfs st;
os_info("Checking if %s is on tmpfs...", dir);
if (statfs(dir, &st) < 0) {
os_info("%s\n", strerror(errno));
} else if (st.f_type != TMPFS_MAGIC) {
os_info("no\n");
} else {
os_info("OK\n");
return 0;
}
return -1;
}
/*
* Choose the tempdir to use. We want something on tmpfs so that our memory is
* not subject to the host's vm.dirty_ratio. If a tempdir is specified in the
* environment, we use that even if it's not on tmpfs, but we warn the user.
* Otherwise, we try common tmpfs locations, and if no tmpfs directory is found
* then we fall back to /tmp.
*/
static char * __init choose_tempdir(void)
{
static const char * const vars[] = {
"TMPDIR",
"TMP",
"TEMP",
NULL
};
static const char fallback_dir[] = "/tmp";
static const char * const tmpfs_dirs[] = {
"/dev/shm",
fallback_dir,
NULL
};
int i;
const char *dir;
os_info("Checking environment variables for a tempdir...");
for (i = 0; vars[i]; i++) {
dir = getenv(vars[i]);
if ((dir != NULL) && (*dir != '\0')) {
os_info("%s\n", dir);
if (check_tmpfs(dir) >= 0)
goto done;
else
goto warn;
}
}
os_info("none found\n");
for (i = 0; tmpfs_dirs[i]; i++) {
dir = tmpfs_dirs[i];
if (check_tmpfs(dir) >= 0)
goto done;
}
dir = fallback_dir;
warn:
os_warn("Warning: tempdir %s is not on tmpfs\n", dir);
done:
/* Make a copy since getenv results may not remain valid forever. */
return strdup(dir);
}
/*
* Create an unlinked tempfile in a suitable tempdir. template must be the
* basename part of the template with a leading '/'.
*/
static int __init make_tempfile(const char *template)
{
char *tempname;
int fd;
if (tempdir == NULL) {
tempdir = choose_tempdir();
if (tempdir == NULL) {
os_warn("Failed to choose tempdir: %s\n",
strerror(errno));
return -1;
}
}
#ifdef O_TMPFILE
fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
/*
* If the running system does not support O_TMPFILE flag then retry
* without it.
*/
if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
errno != EOPNOTSUPP))
return fd;
#endif
tempname = malloc(strlen(tempdir) + strlen(template) + 1);
if (tempname == NULL)
return -1;
strcpy(tempname, tempdir);
strcat(tempname, template);
fd = mkstemp(tempname);
if (fd < 0) {
os_warn("open - cannot create %s: %s\n", tempname,
strerror(errno));
goto out;
}
if (unlink(tempname) < 0) {
perror("unlink");
goto close;
}
free(tempname);
return fd;
close:
close(fd);
out:
free(tempname);
return -1;
}
#define TEMPNAME_TEMPLATE "/vm_file-XXXXXX"
static int __init create_tmp_file(unsigned long long len)
{
int fd, err;
char zero;
fd = make_tempfile(TEMPNAME_TEMPLATE);
if (fd < 0)
exit(1);
/*
* Seek to len - 1 because writing a character there will
* increase the file size by one byte, to the desired length.
*/
if (lseek64(fd, len - 1, SEEK_SET) < 0) {
perror("lseek64");
exit(1);
}
zero = 0;
err = write(fd, &zero, 1);
if (err != 1) {
perror("write");
exit(1);
}
return fd;
}
int __init create_mem_file(unsigned long long len)
{
int err, fd;
fd = create_tmp_file(len);
err = os_set_exec_close(fd);
if (err < 0) {
errno = -err;
perror("exec_close");
}
return fd;
}
void __init check_tmpexec(void)
{
void *addr;
int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
addr = mmap(NULL, UM_KERN_PAGE_SIZE,
PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
os_info("Checking PROT_EXEC mmap in %s...", tempdir);
if (addr == MAP_FAILED) {
err = errno;
os_warn("%s\n", strerror(err));
close(fd);
if (err == EPERM)
os_warn("%s must be not mounted noexec\n", tempdir);
exit(1);
}
os_info("OK\n");
munmap(addr, UM_KERN_PAGE_SIZE);
close(fd);
}
|
