1/* vi: set sw=4 ts=4: */ 2/* 3 * Mini copy_file implementation for busybox 4 * 5 * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu> 6 * SELinux support by Yuichi Nakamura <ynakam@hitachisoft.jp> 7 * 8 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. 9 * 10 */ 11 12#include "libbb.h" 13 14// POSIX: if exists and -i, ask (w/o -i assume yes). 15// Then open w/o EXCL (yes, not unlink!). 16// If open still fails and -f, try unlink, then try open again. 17// Result: a mess: 18// If dest is a softlink, we overwrite softlink's destination! 19// (or fail, if it points to dir/nonexistent location/etc). 20// This is strange, but POSIX-correct. 21// coreutils cp has --remove-destination to override this... 22// 23// NB: we have special code which still allows for "cp file /dev/node" 24// to work POSIX-ly (the only realistic case where it makes sense) 25 26#define DO_POSIX_CP 0 /* 1 - POSIX behavior, 0 - safe behavior */ 27 28// errno must be set to relevant value ("why we cannot create dest?") 29// for POSIX mode to give reasonable error message 30static int ask_and_unlink(const char *dest, int flags) 31{ 32#if DO_POSIX_CP 33 if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) { 34 // Either it exists, or the *path* doesnt exist 35 bb_perror_msg("cannot create '%s'", dest); 36 return -1; 37 } 38#endif 39 // If !DO_POSIX_CP, act as if -f is always in effect - we don't want 40 // "cannot create" msg, we want unlink to be done (silently unless -i). 41 42 // TODO: maybe we should do it only if ctty is present? 43 if (flags & FILEUTILS_INTERACTIVE) { 44 // We would not do POSIX insanity. -i asks, 45 // then _unlinks_ the offender. Presto. 46 // (No "opening without O_EXCL", no "unlink only if -f") 47 // Or else we will end up having 3 open()s! 48 fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest); 49 if (!bb_ask_confirmation()) 50 return 0; // not allowed to overwrite 51 } 52 if (unlink(dest) < 0) { 53 bb_perror_msg("cannot remove '%s'", dest); 54 return -1; // error 55 } 56 return 1; // ok (to try again) 57} 58 59/* Return: 60 * -1 error, copy not made 61 * 0 copy is made or user answered "no" in interactive mode 62 * (failures to preserve mode/owner/times are not reported in exit code) 63 */ 64int copy_file(const char *source, const char *dest, int flags) 65{ 66 /* This is a recursive function, try to minimize stack usage */ 67 /* NB: each struct stat is ~100 bytes */ 68 struct stat source_stat; 69 struct stat dest_stat; 70 signed char retval = 0; 71 signed char dest_exists = 0; 72 signed char ovr; 73 74#define FLAGS_DEREF (flags & FILEUTILS_DEREFERENCE) 75 76 if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) { 77 // This may be a dangling symlink. 78 // Making [sym]links to dangling symlinks works, so... 79 if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) 80 goto make_links; 81 bb_perror_msg("cannot stat '%s'", source); 82 return -1; 83 } 84 85 if (lstat(dest, &dest_stat) < 0) { 86 if (errno != ENOENT) { 87 bb_perror_msg("cannot stat '%s'", dest); 88 return -1; 89 } 90 } else { 91 if (source_stat.st_dev == dest_stat.st_dev 92 && source_stat.st_ino == dest_stat.st_ino 93 ) { 94 bb_error_msg("'%s' and '%s' are the same file", source, dest); 95 return -1; 96 } 97 dest_exists = 1; 98 } 99 100#if ENABLE_SELINUX 101 if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) { 102 security_context_t con; 103 if (lgetfilecon(source, &con) >= 0) { 104 if (setfscreatecon(con) < 0) { 105 bb_perror_msg("cannot set setfscreatecon %s", con); 106 freecon(con); 107 return -1; 108 } 109 } else if (errno == ENOTSUP || errno == ENODATA) { 110 setfscreatecon_or_die(NULL); 111 } else { 112 bb_perror_msg("cannot lgetfilecon %s", source); 113 return -1; 114 } 115 } 116#endif 117 118 if (S_ISDIR(source_stat.st_mode)) { 119 DIR *dp; 120 const char *tp; 121 struct dirent *d; 122 mode_t saved_umask = 0; 123 124 if (!(flags & FILEUTILS_RECUR)) { 125 bb_error_msg("omitting directory '%s'", source); 126 return -1; 127 } 128 129 /* Did we ever create source ourself before? */ 130 tp = is_in_ino_dev_hashtable(&source_stat); 131 if (tp) { 132 /* We did! it's a recursion! man the lifeboats... */ 133 bb_error_msg("recursion detected, omitting directory '%s'", 134 source); 135 return -1; 136 } 137 138 /* Create DEST */ 139 if (dest_exists) { 140 if (!S_ISDIR(dest_stat.st_mode)) { 141 bb_error_msg("target '%s' is not a directory", dest); 142 return -1; 143 } 144 /* race here: user can substitute a symlink between 145 * this check and actual creation of files inside dest */ 146 } else { 147 mode_t mode; 148 saved_umask = umask(0); 149 150 mode = source_stat.st_mode; 151 if (!(flags & FILEUTILS_PRESERVE_STATUS)) 152 mode = source_stat.st_mode & ~saved_umask; 153 /* Allow owner to access new dir (at least for now) */ 154 mode |= S_IRWXU; 155 if (mkdir(dest, mode) < 0) { 156 umask(saved_umask); 157 bb_perror_msg("cannot create directory '%s'", dest); 158 return -1; 159 } 160 umask(saved_umask); 161 /* need stat info for add_to_ino_dev_hashtable */ 162 if (lstat(dest, &dest_stat) < 0) { 163 bb_perror_msg("cannot stat '%s'", dest); 164 return -1; 165 } 166 } 167 /* remember (dev,inode) of each created dir. 168 * NULL: name is not remembered */ 169 add_to_ino_dev_hashtable(&dest_stat, NULL); 170 171 /* Recursively copy files in SOURCE */ 172 dp = opendir(source); 173 if (dp == NULL) { 174 retval = -1; 175 goto preserve_mode_ugid_time; 176 } 177 178 while ((d = readdir(dp)) != NULL) { 179 char *new_source, *new_dest; 180 181 new_source = concat_subpath_file(source, d->d_name); 182 if (new_source == NULL) 183 continue; 184 new_dest = concat_path_file(dest, d->d_name); 185 if (copy_file(new_source, new_dest, flags) < 0) 186 retval = -1; 187 free(new_source); 188 free(new_dest); 189 } 190 closedir(dp); 191 192 if (!dest_exists 193 && chmod(dest, source_stat.st_mode & ~saved_umask) < 0 194 ) { 195 bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest); 196 /* retval = -1; - WRONG! copy *WAS* made */ 197 } 198 goto preserve_mode_ugid_time; 199 } 200 201 if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) { 202 int (*lf)(const char *oldpath, const char *newpath); 203 make_links: 204 // Hmm... maybe 205 // if (DEREF && MAKE_SOFTLINK) source = realpath(source) ? 206 // (but realpath returns NULL on dangling symlinks...) 207 lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link; 208 if (lf(source, dest) < 0) { 209 ovr = ask_and_unlink(dest, flags); 210 if (ovr <= 0) 211 return ovr; 212 if (lf(source, dest) < 0) { 213 bb_perror_msg("cannot create link '%s'", dest); 214 return -1; 215 } 216 } 217 /* _Not_ jumping to preserve_mode_ugid_time: 218 * hard/softlinks don't have those */ 219 return 0; 220 } 221 222 if (S_ISREG(source_stat.st_mode) 223 /* DEREF uses stat, which never returns S_ISLNK() == true. */ 224 /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */ 225 ) { 226 int src_fd; 227 int dst_fd; 228 229 if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) { 230 const char *link_target; 231 link_target = is_in_ino_dev_hashtable(&source_stat); 232 if (link_target) { 233 if (link(link_target, dest) < 0) { 234 ovr = ask_and_unlink(dest, flags); 235 if (ovr <= 0) 236 return ovr; 237 if (link(link_target, dest) < 0) { 238 bb_perror_msg("cannot create link '%s'", dest); 239 return -1; 240 } 241 } 242 return 0; 243 } 244 add_to_ino_dev_hashtable(&source_stat, dest); 245 } 246 247 src_fd = open_or_warn(source, O_RDONLY); 248 if (src_fd < 0) 249 return -1; 250 251 /* POSIX way is a security problem versus symlink attacks, 252 * we do it only for non-symlinks, and only for non-recursive, 253 * non-interactive cp. NB: it is still racy 254 * for "cp file /home/bad_user/file" case 255 * (user can rm file and create a link to /etc/passwd) */ 256 if (DO_POSIX_CP 257 || (dest_exists && !(flags & (FILEUTILS_RECUR|FILEUTILS_INTERACTIVE)) 258 && !S_ISLNK(dest_stat.st_mode)) 259 ) { 260 dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode); 261 } else /* safe way: */ 262 dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode); 263 if (dst_fd == -1) { 264 ovr = ask_and_unlink(dest, flags); 265 if (ovr <= 0) { 266 close(src_fd); 267 return ovr; 268 } 269 /* It shouldn't exist. If it exists, do not open (symlink attack?) */ 270 dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode); 271 if (dst_fd < 0) { 272 close(src_fd); 273 return -1; 274 } 275 } 276 277#if ENABLE_SELINUX 278 if (((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) 279 || (flags & FILEUTILS_SET_SECURITY_CONTEXT)) 280 && is_selinux_enabled() > 0 281 ) { 282 security_context_t con; 283 if (getfscreatecon(&con) == -1) { 284 bb_perror_msg("getfscreatecon"); 285 return -1; 286 } 287 if (con) { 288 if (setfilecon(dest, con) == -1) { 289 bb_perror_msg("setfilecon:%s,%s", dest, con); 290 freecon(con); 291 return -1; 292 } 293 freecon(con); 294 } 295 } 296#endif 297 if (bb_copyfd_eof(src_fd, dst_fd) == -1) 298 retval = -1; 299 /* Ok, writing side I can understand... */ 300 if (close(dst_fd) < 0) { 301 bb_perror_msg("cannot close '%s'", dest); 302 retval = -1; 303 } 304 /* ...but read size is already checked by bb_copyfd_eof */ 305 close(src_fd); 306 goto preserve_mode_ugid_time; 307 } 308 309 /* Source is a symlink or a special file */ 310 /* We are lazy here, a bit lax with races... */ 311 if (dest_exists) { 312 errno = EEXIST; 313 ovr = ask_and_unlink(dest, flags); 314 if (ovr <= 0) 315 return ovr; 316 } 317 if (S_ISLNK(source_stat.st_mode)) { 318 char *lpath = xmalloc_readlink_or_warn(source); 319 if (lpath) { 320 int r = symlink(lpath, dest); 321 free(lpath); 322 if (r < 0) { 323 bb_perror_msg("cannot create symlink '%s'", dest); 324 return -1; 325 } 326 if (flags & FILEUTILS_PRESERVE_STATUS) 327 if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0) 328 bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest); 329 } 330 /* _Not_ jumping to preserve_mode_ugid_time: 331 * symlinks don't have those */ 332 return 0; 333 } 334 if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode) 335 || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode) 336 ) { 337 if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) { 338 bb_perror_msg("cannot create '%s'", dest); 339 return -1; 340 } 341 } else { 342 bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode); 343 return -1; 344 } 345 346 preserve_mode_ugid_time: 347 348 if (flags & FILEUTILS_PRESERVE_STATUS 349 /* Cannot happen: */ 350 /* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */ 351 ) { 352 struct utimbuf times; 353 354 times.actime = source_stat.st_atime; 355 times.modtime = source_stat.st_mtime; 356 /* BTW, utimes sets usec-precision time - just FYI */ 357 if (utime(dest, ×) < 0) 358 bb_perror_msg("cannot preserve %s of '%s'", "times", dest); 359 if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) { 360 source_stat.st_mode &= ~(S_ISUID | S_ISGID); 361 bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest); 362 } 363 if (chmod(dest, source_stat.st_mode) < 0) 364 bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest); 365 } 366 367 return retval; 368} 369