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#include "libbb.h" 11 12// FEATURE_NON_POSIX_CP: 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 (sym)link, we overwrite link 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/* Called if open of destination, link creation etc fails. 24 * errno must be set to relevant value ("why we cannot create dest?") 25 * to give reasonable error message */ 26static int ask_and_unlink(const char *dest, int flags) 27{ 28 int e = errno; 29 30#if !ENABLE_FEATURE_NON_POSIX_CP 31 if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) { 32 /* Either it exists, or the *path* doesnt exist */ 33 bb_perror_msg("can't create '%s'", dest); 34 return -1; 35 } 36#endif 37 // else: act as if -f is always in effect. 38 // We don't want "can't create" msg, we want unlink to be done 39 // (silently unless -i). Why? POSIX cp usually succeeds with 40 // O_TRUNC open of existing file, and user is left ignorantly happy. 41 // With above block unconditionally enabled, non-POSIX cp 42 // will complain a lot more than POSIX one. 43 44 /* TODO: maybe we should do it only if ctty is present? */ 45 if (flags & FILEUTILS_INTERACTIVE) { 46 // We would not do POSIX insanity. -i asks, 47 // then _unlinks_ the offender. Presto. 48 // (No "opening without O_EXCL", no "unlink only if -f") 49 // Or else we will end up having 3 open()s! 50 fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest); 51 if (!bb_ask_confirmation()) 52 return 0; /* not allowed to overwrite */ 53 } 54 if (unlink(dest) < 0) { 55#if ENABLE_FEATURE_VERBOSE_CP_MESSAGE 56 if (e == errno && e == ENOENT) { 57 /* e == ENOTDIR is similar: path has non-dir component, 58 * but in this case we don't even reach copy_file() */ 59 bb_error_msg("can't create '%s': Path does not exist", dest); 60 return -1; /* error */ 61 } 62#endif 63 errno = e; /* do not use errno from unlink */ 64 bb_perror_msg("can't create '%s'", dest); 65 return -1; /* error */ 66 } 67 return 1; /* ok (to try again) */ 68} 69 70/* Return: 71 * -1 error, copy not made 72 * 0 copy is made or user answered "no" in interactive mode 73 * (failures to preserve mode/owner/times are not reported in exit code) 74 */ 75int FAST_FUNC copy_file(const char *source, const char *dest, int flags) 76{ 77 /* This is a recursive function, try to minimize stack usage */ 78 /* NB: each struct stat is ~100 bytes */ 79 struct stat source_stat; 80 struct stat dest_stat; 81 signed char retval = 0; 82 signed char dest_exists = 0; 83 signed char ovr; 84 85/* Inverse of cp -d ("cp without -d") */ 86#define FLAGS_DEREF (flags & (FILEUTILS_DEREFERENCE + FILEUTILS_DEREFERENCE_L0)) 87 88 if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) { 89 /* This may be a dangling symlink. 90 * Making [sym]links to dangling symlinks works, so... */ 91 if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) 92 goto make_links; 93 bb_perror_msg("can't stat '%s'", source); 94 return -1; 95 } 96 97 if (lstat(dest, &dest_stat) < 0) { 98 if (errno != ENOENT) { 99 bb_perror_msg("can't stat '%s'", dest); 100 return -1; 101 } 102 } else { 103 if (source_stat.st_dev == dest_stat.st_dev 104 && source_stat.st_ino == dest_stat.st_ino 105 ) { 106 bb_error_msg("'%s' and '%s' are the same file", source, dest); 107 return -1; 108 } 109 dest_exists = 1; 110 } 111 112#if ENABLE_SELINUX 113 if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) { 114 security_context_t con; 115 if (lgetfilecon(source, &con) >= 0) { 116 if (setfscreatecon(con) < 0) { 117 bb_perror_msg("can't set setfscreatecon %s", con); 118 freecon(con); 119 return -1; 120 } 121 } else if (errno == ENOTSUP || errno == ENODATA) { 122 setfscreatecon_or_die(NULL); 123 } else { 124 bb_perror_msg("can't lgetfilecon %s", source); 125 return -1; 126 } 127 } 128#endif 129 130 if (S_ISDIR(source_stat.st_mode)) { 131 DIR *dp; 132 const char *tp; 133 struct dirent *d; 134 mode_t saved_umask = 0; 135 136 if (!(flags & FILEUTILS_RECUR)) { 137 bb_error_msg("omitting directory '%s'", source); 138 return -1; 139 } 140 141 /* Did we ever create source ourself before? */ 142 tp = is_in_ino_dev_hashtable(&source_stat); 143 if (tp) { 144 /* We did! it's a recursion! man the lifeboats... */ 145 bb_error_msg("recursion detected, omitting directory '%s'", 146 source); 147 return -1; 148 } 149 150 /* Create DEST */ 151 if (dest_exists) { 152 if (!S_ISDIR(dest_stat.st_mode)) { 153 bb_error_msg("target '%s' is not a directory", dest); 154 return -1; 155 } 156 /* race here: user can substitute a symlink between 157 * this check and actual creation of files inside dest */ 158 } else { 159 mode_t mode; 160 saved_umask = umask(0); 161 162 mode = source_stat.st_mode; 163 if (!(flags & FILEUTILS_PRESERVE_STATUS)) 164 mode = source_stat.st_mode & ~saved_umask; 165 /* Allow owner to access new dir (at least for now) */ 166 mode |= S_IRWXU; 167 if (mkdir(dest, mode) < 0) { 168 umask(saved_umask); 169 bb_perror_msg("can't create directory '%s'", dest); 170 return -1; 171 } 172 umask(saved_umask); 173 /* need stat info for add_to_ino_dev_hashtable */ 174 if (lstat(dest, &dest_stat) < 0) { 175 bb_perror_msg("can't stat '%s'", dest); 176 return -1; 177 } 178 } 179 /* remember (dev,inode) of each created dir. 180 * NULL: name is not remembered */ 181 add_to_ino_dev_hashtable(&dest_stat, NULL); 182 183 /* Recursively copy files in SOURCE */ 184 dp = opendir(source); 185 if (dp == NULL) { 186 retval = -1; 187 goto preserve_mode_ugid_time; 188 } 189 190 while ((d = readdir(dp)) != NULL) { 191 char *new_source, *new_dest; 192 193 new_source = concat_subpath_file(source, d->d_name); 194 if (new_source == NULL) 195 continue; 196 new_dest = concat_path_file(dest, d->d_name); 197 if (copy_file(new_source, new_dest, flags & ~FILEUTILS_DEREFERENCE_L0) < 0) 198 retval = -1; 199 free(new_source); 200 free(new_dest); 201 } 202 closedir(dp); 203 204 if (!dest_exists 205 && chmod(dest, source_stat.st_mode & ~saved_umask) < 0 206 ) { 207 bb_perror_msg("can't preserve %s of '%s'", "permissions", dest); 208 /* retval = -1; - WRONG! copy *WAS* made */ 209 } 210 goto preserve_mode_ugid_time; 211 } 212 213 if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) { 214 int (*lf)(const char *oldpath, const char *newpath); 215 make_links: 216 /* Hmm... maybe 217 * if (DEREF && MAKE_SOFTLINK) source = realpath(source) ? 218 * (but realpath returns NULL on dangling symlinks...) */ 219 lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link; 220 if (lf(source, dest) < 0) { 221 ovr = ask_and_unlink(dest, flags); 222 if (ovr <= 0) 223 return ovr; 224 if (lf(source, dest) < 0) { 225 bb_perror_msg("can't create link '%s'", dest); 226 return -1; 227 } 228 } 229 /* _Not_ jumping to preserve_mode_ugid_time: 230 * (sym)links don't have those */ 231 return 0; 232 } 233 234 if (/* "cp thing1 thing2" without -R: just open and read() from thing1 */ 235 !(flags & FILEUTILS_RECUR) 236 /* "cp [-opts] regular_file thing2" */ 237 || S_ISREG(source_stat.st_mode) 238 /* DEREF uses stat, which never returns S_ISLNK() == true. 239 * So the below is never true: */ 240 /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */ 241 ) { 242 int src_fd; 243 int dst_fd; 244 mode_t new_mode; 245 246 if (!FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) { 247 /* "cp -d symlink dst": create a link */ 248 goto dont_cat; 249 } 250 251 if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) { 252 const char *link_target; 253 link_target = is_in_ino_dev_hashtable(&source_stat); 254 if (link_target) { 255 if (link(link_target, dest) < 0) { 256 ovr = ask_and_unlink(dest, flags); 257 if (ovr <= 0) 258 return ovr; 259 if (link(link_target, dest) < 0) { 260 bb_perror_msg("can't create link '%s'", dest); 261 return -1; 262 } 263 } 264 return 0; 265 } 266 add_to_ino_dev_hashtable(&source_stat, dest); 267 } 268 269 src_fd = open_or_warn(source, O_RDONLY); 270 if (src_fd < 0) 271 return -1; 272 273 /* Do not try to open with weird mode fields */ 274 new_mode = source_stat.st_mode; 275 if (!S_ISREG(source_stat.st_mode)) 276 new_mode = 0666; 277 278 // POSIX way is a security problem versus (sym)link attacks 279 if (!ENABLE_FEATURE_NON_POSIX_CP) { 280 dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, new_mode); 281 } else { /* safe way: */ 282 dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode); 283 } 284 if (dst_fd == -1) { 285 ovr = ask_and_unlink(dest, flags); 286 if (ovr <= 0) { 287 close(src_fd); 288 return ovr; 289 } 290 /* It shouldn't exist. If it exists, do not open (symlink attack?) */ 291 dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode); 292 if (dst_fd < 0) { 293 close(src_fd); 294 return -1; 295 } 296 } 297 298#if ENABLE_SELINUX 299 if ((flags & (FILEUTILS_PRESERVE_SECURITY_CONTEXT|FILEUTILS_SET_SECURITY_CONTEXT)) 300 && is_selinux_enabled() > 0 301 ) { 302 security_context_t con; 303 if (getfscreatecon(&con) == -1) { 304 bb_perror_msg("getfscreatecon"); 305 return -1; 306 } 307 if (con) { 308 if (setfilecon(dest, con) == -1) { 309 bb_perror_msg("setfilecon:%s,%s", dest, con); 310 freecon(con); 311 return -1; 312 } 313 freecon(con); 314 } 315 } 316#endif 317 if (bb_copyfd_eof(src_fd, dst_fd) == -1) 318 retval = -1; 319 /* Careful with writing... */ 320 if (close(dst_fd) < 0) { 321 bb_perror_msg("error writing to '%s'", dest); 322 retval = -1; 323 } 324 /* ...but read size is already checked by bb_copyfd_eof */ 325 close(src_fd); 326 /* "cp /dev/something new_file" should not 327 * copy mode of /dev/something */ 328 if (!S_ISREG(source_stat.st_mode)) 329 return retval; 330 goto preserve_mode_ugid_time; 331 } 332 dont_cat: 333 334 /* Source is a symlink or a special file */ 335 /* We are lazy here, a bit lax with races... */ 336 if (dest_exists) { 337 errno = EEXIST; 338 ovr = ask_and_unlink(dest, flags); 339 if (ovr <= 0) 340 return ovr; 341 } 342 if (S_ISLNK(source_stat.st_mode)) { 343 char *lpath = xmalloc_readlink_or_warn(source); 344 if (lpath) { 345 int r = symlink(lpath, dest); 346 free(lpath); 347 if (r < 0) { 348 bb_perror_msg("can't create symlink '%s'", dest); 349 return -1; 350 } 351 if (flags & FILEUTILS_PRESERVE_STATUS) 352 if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0) 353 bb_perror_msg("can't preserve %s of '%s'", "ownership", dest); 354 } 355 /* _Not_ jumping to preserve_mode_ugid_time: 356 * symlinks don't have those */ 357 return 0; 358 } 359 if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode) 360 || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode) 361 ) { 362 if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) { 363 bb_perror_msg("can't create '%s'", dest); 364 return -1; 365 } 366 } else { 367 bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode); 368 return -1; 369 } 370 371 preserve_mode_ugid_time: 372 373 if (flags & FILEUTILS_PRESERVE_STATUS 374 /* Cannot happen: */ 375 /* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */ 376 ) { 377 struct timeval times[2]; 378 379 times[1].tv_sec = times[0].tv_sec = source_stat.st_mtime; 380 times[1].tv_usec = times[0].tv_usec = 0; 381 /* BTW, utimes sets usec-precision time - just FYI */ 382 if (utimes(dest, times) < 0) 383 bb_perror_msg("can't preserve %s of '%s'", "times", dest); 384 if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) { 385 source_stat.st_mode &= ~(S_ISUID | S_ISGID); 386 bb_perror_msg("can't preserve %s of '%s'", "ownership", dest); 387 } 388 if (chmod(dest, source_stat.st_mode) < 0) 389 bb_perror_msg("can't preserve %s of '%s'", "permissions", dest); 390 } 391 392 return retval; 393} 394