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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 <kern_util.h>
19#include <os.h>
20#include "internal.h"
21
22/*
23 * kasan_map_memory - maps memory from @start with a size of @len.
24 * The allocated memory is filled with zeroes upon success.
25 * @start: the start address of the memory to be mapped
26 * @len: the length of the memory to be mapped
27 *
28 * This function is used to map shadow memory for KASAN in uml
29 */
30void kasan_map_memory(void *start, size_t len)
31{
32 if (mmap(start,
33 len,
34 PROT_READ|PROT_WRITE,
35 MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE,
36 -1,
37 0) == MAP_FAILED) {
38 os_info("Couldn't allocate shadow memory: %s\n.",
39 strerror(errno));
40 exit(1);
41 }
42
43 if (madvise(start, len, MADV_DONTDUMP)) {
44 os_info("Couldn't set MAD_DONTDUMP on shadow memory: %s\n.",
45 strerror(errno));
46 exit(1);
47 }
48
49 if (madvise(start, len, MADV_DONTFORK)) {
50 os_info("Couldn't set MADV_DONTFORK on shadow memory: %s\n.",
51 strerror(errno));
52 exit(1);
53 }
54}
55
56/* Set by make_tempfile() during early boot. */
57char *tempdir = NULL;
58
59/* Check if dir is on tmpfs. Return 0 if yes, -1 if no or error. */
60static int __init check_tmpfs(const char *dir)
61{
62 struct statfs st;
63
64 os_info("Checking if %s is on tmpfs...", dir);
65 if (statfs(dir, &st) < 0) {
66 os_info("%s\n", strerror(errno));
67 } else if (st.f_type != TMPFS_MAGIC) {
68 os_info("no\n");
69 } else {
70 os_info("OK\n");
71 return 0;
72 }
73 return -1;
74}
75
76/*
77 * Choose the tempdir to use. We want something on tmpfs so that our memory is
78 * not subject to the host's vm.dirty_ratio. If a tempdir is specified in the
79 * environment, we use that even if it's not on tmpfs, but we warn the user.
80 * Otherwise, we try common tmpfs locations, and if no tmpfs directory is found
81 * then we fall back to /tmp.
82 */
83static char * __init choose_tempdir(void)
84{
85 static const char * const vars[] = {
86 "TMPDIR",
87 "TMP",
88 "TEMP",
89 NULL
90 };
91 static const char fallback_dir[] = "/tmp";
92 static const char * const tmpfs_dirs[] = {
93 "/dev/shm",
94 fallback_dir,
95 NULL
96 };
97 int i;
98 const char *dir;
99
100 os_info("Checking environment variables for a tempdir...");
101 for (i = 0; vars[i]; i++) {
102 dir = getenv(vars[i]);
103 if ((dir != NULL) && (*dir != '\0')) {
104 os_info("%s\n", dir);
105 if (check_tmpfs(dir) >= 0)
106 goto done;
107 else
108 goto warn;
109 }
110 }
111 os_info("none found\n");
112
113 for (i = 0; tmpfs_dirs[i]; i++) {
114 dir = tmpfs_dirs[i];
115 if (check_tmpfs(dir) >= 0)
116 goto done;
117 }
118
119 dir = fallback_dir;
120warn:
121 os_warn("Warning: tempdir %s is not on tmpfs\n", dir);
122done:
123 /* Make a copy since getenv results may not remain valid forever. */
124 return strdup(dir);
125}
126
127/*
128 * Create an unlinked tempfile in a suitable tempdir. template must be the
129 * basename part of the template with a leading '/'.
130 */
131static int __init make_tempfile(const char *template)
132{
133 char *tempname;
134 int fd;
135
136 if (tempdir == NULL) {
137 tempdir = choose_tempdir();
138 if (tempdir == NULL) {
139 os_warn("Failed to choose tempdir: %s\n",
140 strerror(errno));
141 return -1;
142 }
143 }
144
145#ifdef O_TMPFILE
146 fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
147 /*
148 * If the running system does not support O_TMPFILE flag then retry
149 * without it.
150 */
151 if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
152 errno != EOPNOTSUPP))
153 return fd;
154#endif
155
156 tempname = malloc(strlen(tempdir) + strlen(template) + 1);
157 if (tempname == NULL)
158 return -1;
159
160 strcpy(tempname, tempdir);
161 strcat(tempname, template);
162 fd = mkstemp(tempname);
163 if (fd < 0) {
164 os_warn("open - cannot create %s: %s\n", tempname,
165 strerror(errno));
166 goto out;
167 }
168 if (unlink(tempname) < 0) {
169 perror("unlink");
170 goto close;
171 }
172 free(tempname);
173 return fd;
174close:
175 close(fd);
176out:
177 free(tempname);
178 return -1;
179}
180
181#define TEMPNAME_TEMPLATE "/vm_file-XXXXXX"
182
183static int __init create_tmp_file(unsigned long long len)
184{
185 int fd, err;
186 char zero;
187
188 fd = make_tempfile(TEMPNAME_TEMPLATE);
189 if (fd < 0)
190 exit(1);
191
192 /*
193 * Seek to len - 1 because writing a character there will
194 * increase the file size by one byte, to the desired length.
195 */
196 if (lseek64(fd, len - 1, SEEK_SET) < 0) {
197 perror("lseek64");
198 exit(1);
199 }
200
201 zero = 0;
202
203 err = write(fd, &zero, 1);
204 if (err != 1) {
205 perror("write");
206 exit(1);
207 }
208
209 return fd;
210}
211
212int __init create_mem_file(unsigned long long len)
213{
214 int err, fd;
215
216 fd = create_tmp_file(len);
217
218 err = os_set_exec_close(fd);
219 if (err < 0) {
220 errno = -err;
221 perror("exec_close");
222 }
223 return fd;
224}
225
226void __init check_tmpexec(void)
227{
228 void *addr;
229 int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
230
231 addr = mmap(NULL, UM_KERN_PAGE_SIZE,
232 PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
233 os_info("Checking PROT_EXEC mmap in %s...", tempdir);
234 if (addr == MAP_FAILED) {
235 err = errno;
236 os_warn("%s\n", strerror(err));
237 close(fd);
238 if (err == EPERM)
239 os_warn("%s must be not mounted noexec\n", tempdir);
240 exit(1);
241 }
242 os_info("OK\n");
243 munmap(addr, UM_KERN_PAGE_SIZE);
244
245 close(fd);
246}
1/*
2 * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
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/* Set by make_tempfile() during early boot. */
21static char *tempdir = NULL;
22
23/* Check if dir is on tmpfs. Return 0 if yes, -1 if no or error. */
24static int __init check_tmpfs(const char *dir)
25{
26 struct statfs st;
27
28 printf("Checking if %s is on tmpfs...", dir);
29 if (statfs(dir, &st) < 0) {
30 printf("%s\n", strerror(errno));
31 } else if (st.f_type != TMPFS_MAGIC) {
32 printf("no\n");
33 } else {
34 printf("OK\n");
35 return 0;
36 }
37 return -1;
38}
39
40/*
41 * Choose the tempdir to use. We want something on tmpfs so that our memory is
42 * not subject to the host's vm.dirty_ratio. If a tempdir is specified in the
43 * environment, we use that even if it's not on tmpfs, but we warn the user.
44 * Otherwise, we try common tmpfs locations, and if no tmpfs directory is found
45 * then we fall back to /tmp.
46 */
47static char * __init choose_tempdir(void)
48{
49 static const char * const vars[] = {
50 "TMPDIR",
51 "TMP",
52 "TEMP",
53 NULL
54 };
55 static const char fallback_dir[] = "/tmp";
56 static const char * const tmpfs_dirs[] = {
57 "/dev/shm",
58 fallback_dir,
59 NULL
60 };
61 int i;
62 const char *dir;
63
64 printf("Checking environment variables for a tempdir...");
65 for (i = 0; vars[i]; i++) {
66 dir = getenv(vars[i]);
67 if ((dir != NULL) && (*dir != '\0')) {
68 printf("%s\n", dir);
69 if (check_tmpfs(dir) >= 0)
70 goto done;
71 else
72 goto warn;
73 }
74 }
75 printf("none found\n");
76
77 for (i = 0; tmpfs_dirs[i]; i++) {
78 dir = tmpfs_dirs[i];
79 if (check_tmpfs(dir) >= 0)
80 goto done;
81 }
82
83 dir = fallback_dir;
84warn:
85 printf("Warning: tempdir %s is not on tmpfs\n", dir);
86done:
87 /* Make a copy since getenv results may not remain valid forever. */
88 return strdup(dir);
89}
90
91/*
92 * Create an unlinked tempfile in a suitable tempdir. template must be the
93 * basename part of the template with a leading '/'.
94 */
95static int __init make_tempfile(const char *template)
96{
97 char *tempname;
98 int fd;
99
100 if (tempdir == NULL) {
101 tempdir = choose_tempdir();
102 if (tempdir == NULL) {
103 fprintf(stderr, "Failed to choose tempdir: %s\n",
104 strerror(errno));
105 return -1;
106 }
107 }
108
109#ifdef O_TMPFILE
110 fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
111 /*
112 * If the running system does not support O_TMPFILE flag then retry
113 * without it.
114 */
115 if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
116 errno != EOPNOTSUPP))
117 return fd;
118#endif
119
120 tempname = malloc(strlen(tempdir) + strlen(template) + 1);
121 if (tempname == NULL)
122 return -1;
123
124 strcpy(tempname, tempdir);
125 strcat(tempname, template);
126 fd = mkstemp(tempname);
127 if (fd < 0) {
128 fprintf(stderr, "open - cannot create %s: %s\n", tempname,
129 strerror(errno));
130 goto out;
131 }
132 if (unlink(tempname) < 0) {
133 perror("unlink");
134 goto close;
135 }
136 free(tempname);
137 return fd;
138close:
139 close(fd);
140out:
141 free(tempname);
142 return -1;
143}
144
145#define TEMPNAME_TEMPLATE "/vm_file-XXXXXX"
146
147static int __init create_tmp_file(unsigned long long len)
148{
149 int fd, err;
150 char zero;
151
152 fd = make_tempfile(TEMPNAME_TEMPLATE);
153 if (fd < 0)
154 exit(1);
155
156 /*
157 * Seek to len - 1 because writing a character there will
158 * increase the file size by one byte, to the desired length.
159 */
160 if (lseek64(fd, len - 1, SEEK_SET) < 0) {
161 perror("lseek64");
162 exit(1);
163 }
164
165 zero = 0;
166
167 err = write(fd, &zero, 1);
168 if (err != 1) {
169 perror("write");
170 exit(1);
171 }
172
173 return fd;
174}
175
176int __init create_mem_file(unsigned long long len)
177{
178 int err, fd;
179
180 fd = create_tmp_file(len);
181
182 err = os_set_exec_close(fd);
183 if (err < 0) {
184 errno = -err;
185 perror("exec_close");
186 }
187 return fd;
188}
189
190void __init check_tmpexec(void)
191{
192 void *addr;
193 int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
194
195 addr = mmap(NULL, UM_KERN_PAGE_SIZE,
196 PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
197 printf("Checking PROT_EXEC mmap in %s...", tempdir);
198 if (addr == MAP_FAILED) {
199 err = errno;
200 printf("%s\n", strerror(err));
201 close(fd);
202 if (err == EPERM)
203 printf("%s must be not mounted noexec\n", tempdir);
204 exit(1);
205 }
206 printf("OK\n");
207 munmap(addr, UM_KERN_PAGE_SIZE);
208
209 close(fd);
210}