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