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; 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 memmove(buf, ptr, strlen(ptr) + 1); 73 return 1; 74 } 75 76 static int checked_tmpdir = 0; 77 78 /* Look for a tmpfs mounted at /dev/shm. I couldn't find a cleaner 79 * way to do this than to parse /proc/mounts. statfs will return the 80 * same filesystem magic number and fs id for both /dev and /dev/shm 81 * when they are both tmpfs, so you can't tell if they are different 82 * filesystems. Also, there seems to be no other way of finding the 83 * mount point of a filesystem from within it. 84 * 85 * If a /dev/shm tmpfs entry is found, then we switch to using it. 86 * Otherwise, we stay with the default /tmp. 87 */ 88 static void which_tmpdir(void) 89 { 90 int fd, found; 91 char buf[128] = { '\0' }; 92 93 if(checked_tmpdir) 94 return; 95 96 checked_tmpdir = 1; 97 98 printf("Checking for tmpfs mount on /dev/shm..."); 99 100 fd = open("/proc/mounts", O_RDONLY); 101 if(fd < 0){ 102 printf("failed to open /proc/mounts, errno = %d\n", errno); 103 return; 104 } 105 106 while(1){ 107 found = next(fd, buf, sizeof(buf) / sizeof(buf[0]), ' '); 108 if(found != 1) 109 break; 110 111 if(!strncmp(buf, "/dev/shm", strlen("/dev/shm"))) 112 goto found; 113 114 found = next(fd, buf, sizeof(buf) / sizeof(buf[0]), '\n'); 115 if(found != 1) 116 break; 117 } 118 119 err: 120 if(found == 0) 121 printf("nothing mounted on /dev/shm\n"); 122 else if(found < 0) 123 printf("read returned errno %d\n", -found); 124 125 return; 126 127 found: 128 found = next(fd, buf, sizeof(buf) / sizeof(buf[0]), ' '); 129 if(found != 1) 130 goto err; 131 132 if(strncmp(buf, "tmpfs", strlen("tmpfs"))){ 133 printf("not tmpfs\n"); 134 return; 135 } 136 137 printf("OK\n"); 138 default_tmpdir = "/dev/shm"; 139 } 140 141 /* 142 * This proc still used in tt-mode 143 * (file: kernel/tt/ptproxy/proxy.c, proc: start_debugger). 144 * So it isn't 'static' yet. 145 */ 146 int make_tempfile(const char *template, char **out_tempname, int do_unlink) 147 { 148 char *tempname; 149 int fd; 150 151 which_tmpdir(); 152 tempname = malloc(MAXPATHLEN); 153 154 find_tempdir(); 155 if (template[0] != '/') 156 strcpy(tempname, tempdir); 157 else 158 tempname[0] = '\0'; 159 strcat(tempname, template); 160 fd = mkstemp(tempname); 161 if(fd < 0){ 162 fprintf(stderr, "open - cannot create %s: %s\n", tempname, 163 strerror(errno)); 164 goto out; 165 } 166 if(do_unlink && (unlink(tempname) < 0)){ 167 perror("unlink"); 168 goto out; 169 } 170 if(out_tempname){ 171 *out_tempname = tempname; 172 } else { 173 free(tempname); 174 } 175 return(fd); 176 out: 177 free(tempname); 178 return -1; 179 } 180 181 #define TEMPNAME_TEMPLATE "vm_file-XXXXXX" 182 183 /* 184 * This proc is used in start_up.c 185 * So it isn't 'static'. 186 */ 187 int create_tmp_file(unsigned long long len) 188 { 189 int fd, err; 190 char zero; 191 192 fd = make_tempfile(TEMPNAME_TEMPLATE, NULL, 1); 193 if(fd < 0) { 194 exit(1); 195 } 196 197 err = fchmod(fd, 0777); 198 if(err < 0){ 199 perror("os_mode_fd"); 200 exit(1); 201 } 202 203 if (lseek64(fd, len, SEEK_SET) < 0) { 204 perror("os_seek_file"); 205 exit(1); 206 } 207 208 zero = 0; 209 210 err = os_write_file(fd, &zero, 1); 211 if(err != 1){ 212 errno = -err; 213 perror("os_write_file"); 214 exit(1); 215 } 216 217 return(fd); 218 } 219 220 int create_mem_file(unsigned long long len) 221 { 222 int err, fd; 223 224 fd = create_tmp_file(len); 225 226 err = os_set_exec_close(fd, 1); 227 if(err < 0){ 228 errno = -err; 229 perror("exec_close"); 230 } 231 return(fd); 232 } 233 234 235 void check_tmpexec(void) 236 { 237 void *addr; 238 int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE); 239 240 addr = mmap(NULL, UM_KERN_PAGE_SIZE, 241 PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0); 242 printf("Checking PROT_EXEC mmap in %s...",tempdir); 243 fflush(stdout); 244 if(addr == MAP_FAILED){ 245 err = errno; 246 perror("failed"); 247 if(err == EPERM) 248 printf("%s must be not mounted noexec\n",tempdir); 249 exit(1); 250 } 251 printf("OK\n"); 252 munmap(addr, UM_KERN_PAGE_SIZE); 253 254 close(fd); 255 } 256