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