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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 */
5
6#include <stdio.h>
7#include <stddef.h>
8#include <stdlib.h>
9#include <unistd.h>
10#include <errno.h>
11#include <fcntl.h>
12#include <string.h>
13#include <sys/stat.h>
14#include <sys/mman.h>
15#include <sys/vfs.h>
16#include <linux/magic.h>
17#include <init.h>
18#include <os.h>
19
20/*
21 * kasan_map_memory - maps memory from @start with a size of @len.
22 * The allocated memory is filled with zeroes upon success.
23 * @start: the start address of the memory to be mapped
24 * @len: the length of the memory to be mapped
25 *
26 * This function is used to map shadow memory for KASAN in uml
27 */
28void kasan_map_memory(void *start, size_t len)
29{
30 if (mmap(start,
31 len,
32 PROT_READ|PROT_WRITE,
33 MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE,
34 -1,
35 0) == MAP_FAILED) {
36 os_info("Couldn't allocate shadow memory: %s\n.",
37 strerror(errno));
38 exit(1);
39 }
40}
41
42/* Set by make_tempfile() during early boot. */
43static char *tempdir = NULL;
44
45/* Check if dir is on tmpfs. Return 0 if yes, -1 if no or error. */
46static int __init check_tmpfs(const char *dir)
47{
48 struct statfs st;
49
50 os_info("Checking if %s is on tmpfs...", dir);
51 if (statfs(dir, &st) < 0) {
52 os_info("%s\n", strerror(errno));
53 } else if (st.f_type != TMPFS_MAGIC) {
54 os_info("no\n");
55 } else {
56 os_info("OK\n");
57 return 0;
58 }
59 return -1;
60}
61
62/*
63 * Choose the tempdir to use. We want something on tmpfs so that our memory is
64 * not subject to the host's vm.dirty_ratio. If a tempdir is specified in the
65 * environment, we use that even if it's not on tmpfs, but we warn the user.
66 * Otherwise, we try common tmpfs locations, and if no tmpfs directory is found
67 * then we fall back to /tmp.
68 */
69static char * __init choose_tempdir(void)
70{
71 static const char * const vars[] = {
72 "TMPDIR",
73 "TMP",
74 "TEMP",
75 NULL
76 };
77 static const char fallback_dir[] = "/tmp";
78 static const char * const tmpfs_dirs[] = {
79 "/dev/shm",
80 fallback_dir,
81 NULL
82 };
83 int i;
84 const char *dir;
85
86 os_info("Checking environment variables for a tempdir...");
87 for (i = 0; vars[i]; i++) {
88 dir = getenv(vars[i]);
89 if ((dir != NULL) && (*dir != '\0')) {
90 os_info("%s\n", dir);
91 if (check_tmpfs(dir) >= 0)
92 goto done;
93 else
94 goto warn;
95 }
96 }
97 os_info("none found\n");
98
99 for (i = 0; tmpfs_dirs[i]; i++) {
100 dir = tmpfs_dirs[i];
101 if (check_tmpfs(dir) >= 0)
102 goto done;
103 }
104
105 dir = fallback_dir;
106warn:
107 os_warn("Warning: tempdir %s is not on tmpfs\n", dir);
108done:
109 /* Make a copy since getenv results may not remain valid forever. */
110 return strdup(dir);
111}
112
113/*
114 * Create an unlinked tempfile in a suitable tempdir. template must be the
115 * basename part of the template with a leading '/'.
116 */
117static int __init make_tempfile(const char *template)
118{
119 char *tempname;
120 int fd;
121
122 if (tempdir == NULL) {
123 tempdir = choose_tempdir();
124 if (tempdir == NULL) {
125 os_warn("Failed to choose tempdir: %s\n",
126 strerror(errno));
127 return -1;
128 }
129 }
130
131#ifdef O_TMPFILE
132 fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
133 /*
134 * If the running system does not support O_TMPFILE flag then retry
135 * without it.
136 */
137 if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
138 errno != EOPNOTSUPP))
139 return fd;
140#endif
141
142 tempname = malloc(strlen(tempdir) + strlen(template) + 1);
143 if (tempname == NULL)
144 return -1;
145
146 strcpy(tempname, tempdir);
147 strcat(tempname, template);
148 fd = mkstemp(tempname);
149 if (fd < 0) {
150 os_warn("open - cannot create %s: %s\n", tempname,
151 strerror(errno));
152 goto out;
153 }
154 if (unlink(tempname) < 0) {
155 perror("unlink");
156 goto close;
157 }
158 free(tempname);
159 return fd;
160close:
161 close(fd);
162out:
163 free(tempname);
164 return -1;
165}
166
167#define TEMPNAME_TEMPLATE "/vm_file-XXXXXX"
168
169static int __init create_tmp_file(unsigned long long len)
170{
171 int fd, err;
172 char zero;
173
174 fd = make_tempfile(TEMPNAME_TEMPLATE);
175 if (fd < 0)
176 exit(1);
177
178 /*
179 * Seek to len - 1 because writing a character there will
180 * increase the file size by one byte, to the desired length.
181 */
182 if (lseek64(fd, len - 1, SEEK_SET) < 0) {
183 perror("lseek64");
184 exit(1);
185 }
186
187 zero = 0;
188
189 err = write(fd, &zero, 1);
190 if (err != 1) {
191 perror("write");
192 exit(1);
193 }
194
195 return fd;
196}
197
198int __init create_mem_file(unsigned long long len)
199{
200 int err, fd;
201
202 fd = create_tmp_file(len);
203
204 err = os_set_exec_close(fd);
205 if (err < 0) {
206 errno = -err;
207 perror("exec_close");
208 }
209 return fd;
210}
211
212void __init check_tmpexec(void)
213{
214 void *addr;
215 int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
216
217 addr = mmap(NULL, UM_KERN_PAGE_SIZE,
218 PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
219 os_info("Checking PROT_EXEC mmap in %s...", tempdir);
220 if (addr == MAP_FAILED) {
221 err = errno;
222 os_warn("%s\n", strerror(err));
223 close(fd);
224 if (err == EPERM)
225 os_warn("%s must be not mounted noexec\n", tempdir);
226 exit(1);
227 }
228 os_info("OK\n");
229 munmap(addr, UM_KERN_PAGE_SIZE);
230
231 close(fd);
232}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 */
5
6#include <stdio.h>
7#include <stddef.h>
8#include <stdlib.h>
9#include <unistd.h>
10#include <errno.h>
11#include <fcntl.h>
12#include <string.h>
13#include <sys/stat.h>
14#include <sys/mman.h>
15#include <sys/vfs.h>
16#include <linux/magic.h>
17#include <init.h>
18#include <kern_util.h>
19#include <os.h>
20
21/*
22 * kasan_map_memory - maps memory from @start with a size of @len.
23 * The allocated memory is filled with zeroes upon success.
24 * @start: the start address of the memory to be mapped
25 * @len: the length of the memory to be mapped
26 *
27 * This function is used to map shadow memory for KASAN in uml
28 */
29void kasan_map_memory(void *start, size_t len)
30{
31 if (mmap(start,
32 len,
33 PROT_READ|PROT_WRITE,
34 MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE,
35 -1,
36 0) == MAP_FAILED) {
37 os_info("Couldn't allocate shadow memory: %s\n.",
38 strerror(errno));
39 exit(1);
40 }
41}
42
43/* Set by make_tempfile() during early boot. */
44static char *tempdir = NULL;
45
46/* Check if dir is on tmpfs. Return 0 if yes, -1 if no or error. */
47static int __init check_tmpfs(const char *dir)
48{
49 struct statfs st;
50
51 os_info("Checking if %s is on tmpfs...", dir);
52 if (statfs(dir, &st) < 0) {
53 os_info("%s\n", strerror(errno));
54 } else if (st.f_type != TMPFS_MAGIC) {
55 os_info("no\n");
56 } else {
57 os_info("OK\n");
58 return 0;
59 }
60 return -1;
61}
62
63/*
64 * Choose the tempdir to use. We want something on tmpfs so that our memory is
65 * not subject to the host's vm.dirty_ratio. If a tempdir is specified in the
66 * environment, we use that even if it's not on tmpfs, but we warn the user.
67 * Otherwise, we try common tmpfs locations, and if no tmpfs directory is found
68 * then we fall back to /tmp.
69 */
70static char * __init choose_tempdir(void)
71{
72 static const char * const vars[] = {
73 "TMPDIR",
74 "TMP",
75 "TEMP",
76 NULL
77 };
78 static const char fallback_dir[] = "/tmp";
79 static const char * const tmpfs_dirs[] = {
80 "/dev/shm",
81 fallback_dir,
82 NULL
83 };
84 int i;
85 const char *dir;
86
87 os_info("Checking environment variables for a tempdir...");
88 for (i = 0; vars[i]; i++) {
89 dir = getenv(vars[i]);
90 if ((dir != NULL) && (*dir != '\0')) {
91 os_info("%s\n", dir);
92 if (check_tmpfs(dir) >= 0)
93 goto done;
94 else
95 goto warn;
96 }
97 }
98 os_info("none found\n");
99
100 for (i = 0; tmpfs_dirs[i]; i++) {
101 dir = tmpfs_dirs[i];
102 if (check_tmpfs(dir) >= 0)
103 goto done;
104 }
105
106 dir = fallback_dir;
107warn:
108 os_warn("Warning: tempdir %s is not on tmpfs\n", dir);
109done:
110 /* Make a copy since getenv results may not remain valid forever. */
111 return strdup(dir);
112}
113
114/*
115 * Create an unlinked tempfile in a suitable tempdir. template must be the
116 * basename part of the template with a leading '/'.
117 */
118static int __init make_tempfile(const char *template)
119{
120 char *tempname;
121 int fd;
122
123 if (tempdir == NULL) {
124 tempdir = choose_tempdir();
125 if (tempdir == NULL) {
126 os_warn("Failed to choose tempdir: %s\n",
127 strerror(errno));
128 return -1;
129 }
130 }
131
132#ifdef O_TMPFILE
133 fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
134 /*
135 * If the running system does not support O_TMPFILE flag then retry
136 * without it.
137 */
138 if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
139 errno != EOPNOTSUPP))
140 return fd;
141#endif
142
143 tempname = malloc(strlen(tempdir) + strlen(template) + 1);
144 if (tempname == NULL)
145 return -1;
146
147 strcpy(tempname, tempdir);
148 strcat(tempname, template);
149 fd = mkstemp(tempname);
150 if (fd < 0) {
151 os_warn("open - cannot create %s: %s\n", tempname,
152 strerror(errno));
153 goto out;
154 }
155 if (unlink(tempname) < 0) {
156 perror("unlink");
157 goto close;
158 }
159 free(tempname);
160 return fd;
161close:
162 close(fd);
163out:
164 free(tempname);
165 return -1;
166}
167
168#define TEMPNAME_TEMPLATE "/vm_file-XXXXXX"
169
170static int __init create_tmp_file(unsigned long long len)
171{
172 int fd, err;
173 char zero;
174
175 fd = make_tempfile(TEMPNAME_TEMPLATE);
176 if (fd < 0)
177 exit(1);
178
179 /*
180 * Seek to len - 1 because writing a character there will
181 * increase the file size by one byte, to the desired length.
182 */
183 if (lseek64(fd, len - 1, SEEK_SET) < 0) {
184 perror("lseek64");
185 exit(1);
186 }
187
188 zero = 0;
189
190 err = write(fd, &zero, 1);
191 if (err != 1) {
192 perror("write");
193 exit(1);
194 }
195
196 return fd;
197}
198
199int __init create_mem_file(unsigned long long len)
200{
201 int err, fd;
202
203 fd = create_tmp_file(len);
204
205 err = os_set_exec_close(fd);
206 if (err < 0) {
207 errno = -err;
208 perror("exec_close");
209 }
210 return fd;
211}
212
213void __init check_tmpexec(void)
214{
215 void *addr;
216 int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
217
218 addr = mmap(NULL, UM_KERN_PAGE_SIZE,
219 PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
220 os_info("Checking PROT_EXEC mmap in %s...", tempdir);
221 if (addr == MAP_FAILED) {
222 err = errno;
223 os_warn("%s\n", strerror(err));
224 close(fd);
225 if (err == EPERM)
226 os_warn("%s must be not mounted noexec\n", tempdir);
227 exit(1);
228 }
229 os_info("OK\n");
230 munmap(addr, UM_KERN_PAGE_SIZE);
231
232 close(fd);
233}