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 source tree.
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 */
ask_and_unlink(const char * dest,int flags)26 static 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 #if ENABLE_FEATURE_CP_LONG_OPTIONS
68 	if (flags & FILEUTILS_RMDEST)
69 		if (flags & FILEUTILS_VERBOSE)
70 			printf("removed '%s'\n", dest);
71 #endif
72 	return 1; /* ok (to try again) */
73 }
74 
75 /* Return:
76  * -1 error, copy not made
77  *  0 copy is made or user answered "no" in interactive mode
78  *    (failures to preserve mode/owner/times are not reported in exit code)
79  */
copy_file(const char * source,const char * dest,int flags)80 int FAST_FUNC copy_file(const char *source, const char *dest, int flags)
81 {
82 	/* This is a recursive function, try to minimize stack usage */
83 	/* NB: each struct stat is ~100 bytes */
84 	struct stat source_stat;
85 	struct stat dest_stat;
86 	smallint retval = 0;
87 	smallint dest_exists = 0;
88 	smallint ovr;
89 
90 /* Inverse of cp -d ("cp without -d") */
91 #define FLAGS_DEREF (flags & (FILEUTILS_DEREFERENCE + FILEUTILS_DEREFERENCE_L0))
92 
93 	if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
94 		/* This may be a dangling symlink.
95 		 * Making [sym]links to dangling symlinks works, so... */
96 		if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK))
97 			goto make_links;
98 		bb_perror_msg("can't stat '%s'", source);
99 		return -1;
100 	}
101 
102 	if (lstat(dest, &dest_stat) < 0) {
103 		if (errno != ENOENT) {
104 			bb_perror_msg("can't stat '%s'", dest);
105 			return -1;
106 		}
107 	} else {
108 		if (source_stat.st_dev == dest_stat.st_dev
109 		 && source_stat.st_ino == dest_stat.st_ino
110 		) {
111 			bb_error_msg("'%s' and '%s' are the same file", source, dest);
112 			return -1;
113 		}
114 		dest_exists = 1;
115 	}
116 
117 #if ENABLE_SELINUX
118 	if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) {
119 		security_context_t con;
120 		if (lgetfilecon(source, &con) >= 0) {
121 			if (setfscreatecon(con) < 0) {
122 				bb_perror_msg("can't set setfscreatecon %s", con);
123 				freecon(con);
124 				return -1;
125 			}
126 		} else if (errno == ENOTSUP || errno == ENODATA) {
127 			setfscreatecon_or_die(NULL);
128 		} else {
129 			bb_perror_msg("can't lgetfilecon %s", source);
130 			return -1;
131 		}
132 	}
133 #endif
134 
135 	if (S_ISDIR(source_stat.st_mode)) {
136 		DIR *dp;
137 		const char *tp;
138 		struct dirent *d;
139 		mode_t saved_umask = 0;
140 
141 		if (!(flags & FILEUTILS_RECUR)) {
142 			bb_error_msg("omitting directory '%s'", source);
143 			return -1;
144 		}
145 
146 		/* Did we ever create source ourself before? */
147 		tp = is_in_ino_dev_hashtable(&source_stat);
148 		if (tp) {
149 			/* We did! it's a recursion! man the lifeboats... */
150 			bb_error_msg("recursion detected, omitting directory '%s'",
151 					source);
152 			return -1;
153 		}
154 
155 		if (dest_exists) {
156 			if (!S_ISDIR(dest_stat.st_mode)) {
157 				bb_error_msg("target '%s' is not a directory", dest);
158 				return -1;
159 			}
160 			/* race here: user can substitute a symlink between
161 			 * this check and actual creation of files inside dest */
162 		} else {
163 			/* Create DEST */
164 			mode_t mode;
165 			saved_umask = umask(0);
166 
167 			mode = source_stat.st_mode;
168 			if (!(flags & FILEUTILS_PRESERVE_STATUS))
169 				mode = source_stat.st_mode & ~saved_umask;
170 			/* Allow owner to access new dir (at least for now) */
171 			mode |= S_IRWXU;
172 			if (mkdir(dest, mode) < 0) {
173 				umask(saved_umask);
174 				bb_perror_msg("can't create directory '%s'", dest);
175 				return -1;
176 			}
177 			umask(saved_umask);
178 			/* need stat info for add_to_ino_dev_hashtable */
179 			if (lstat(dest, &dest_stat) < 0) {
180 				bb_perror_msg("can't stat '%s'", dest);
181 				return -1;
182 			}
183 		}
184 		/* remember (dev,inode) of each created dir.
185 		 * NULL: name is not remembered */
186 		add_to_ino_dev_hashtable(&dest_stat, NULL);
187 
188 		/* Recursively copy files in SOURCE */
189 		dp = opendir(source);
190 		if (dp == NULL) {
191 			retval = -1;
192 			goto preserve_mode_ugid_time;
193 		}
194 
195 		while ((d = readdir(dp)) != NULL) {
196 			char *new_source, *new_dest;
197 
198 			new_source = concat_subpath_file(source, d->d_name);
199 			if (new_source == NULL)
200 				continue;
201 			new_dest = concat_path_file(dest, d->d_name);
202 			if (copy_file(new_source, new_dest, flags & ~FILEUTILS_DEREFERENCE_L0) < 0)
203 				retval = -1;
204 			free(new_source);
205 			free(new_dest);
206 		}
207 		closedir(dp);
208 
209 		if (!dest_exists
210 		 && chmod(dest, source_stat.st_mode & ~saved_umask) < 0
211 		) {
212 			bb_perror_msg("can't preserve %s of '%s'", "permissions", dest);
213 			/* retval = -1; - WRONG! copy *WAS* made */
214 		}
215 		goto preserve_mode_ugid_time;
216 	}
217 
218 	if (dest_exists) {
219 		if (flags & FILEUTILS_UPDATE) {
220 			if (source_stat.st_mtime <= dest_stat.st_mtime) {
221 				return 0; /* source file must be newer */
222 			}
223 		}
224 #if ENABLE_FEATURE_CP_LONG_OPTIONS
225 		if (flags & FILEUTILS_RMDEST) {
226 			ovr = ask_and_unlink(dest, flags);
227 			if (ovr <= 0)
228 				return ovr;
229 			dest_exists = 0;
230 		}
231 #endif
232 	}
233 
234 	if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
235 		int (*lf)(const char *oldpath, const char *newpath);
236  make_links:
237 		/* Hmm... maybe
238 		 * if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
239 		 * (but realpath returns NULL on dangling symlinks...) */
240 		lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
241 		if (lf(source, dest) < 0) {
242 			ovr = ask_and_unlink(dest, flags);
243 			if (ovr <= 0)
244 				return ovr;
245 			if (lf(source, dest) < 0) {
246 				bb_perror_msg("can't create link '%s'", dest);
247 				return -1;
248 			}
249 		}
250 		/* _Not_ jumping to preserve_mode_ugid_time:
251 		 * (sym)links don't have those */
252 		return 0;
253 	}
254 
255 	if (/* "cp thing1 thing2" without -R: just open and read() from thing1 */
256 	    !(flags & FILEUTILS_RECUR)
257 	    /* "cp [-opts] regular_file thing2" */
258 	 || S_ISREG(source_stat.st_mode)
259 	 /* DEREF uses stat, which never returns S_ISLNK() == true.
260 	  * So the below is never true: */
261 	 /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
262 	) {
263 		int src_fd;
264 		int dst_fd;
265 		mode_t new_mode;
266 
267 		if (!FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) {
268 			/* "cp -d symlink dst": create a link */
269 			goto dont_cat;
270 		}
271 
272 		if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
273 			const char *link_target;
274 			link_target = is_in_ino_dev_hashtable(&source_stat);
275 			if (link_target) {
276 				if (link(link_target, dest) < 0) {
277 					ovr = ask_and_unlink(dest, flags);
278 					if (ovr <= 0)
279 						return ovr;
280 					if (link(link_target, dest) < 0) {
281 						bb_perror_msg("can't create link '%s'", dest);
282 						return -1;
283 					}
284 				}
285 				return 0;
286 			}
287 			add_to_ino_dev_hashtable(&source_stat, dest);
288 		}
289 
290 		src_fd = open_or_warn(source, O_RDONLY);
291 		if (src_fd < 0)
292 			return -1;
293 
294 		/* Do not try to open with weird mode fields */
295 		new_mode = source_stat.st_mode;
296 		if (!S_ISREG(source_stat.st_mode))
297 			new_mode = 0666;
298 
299 		if (ENABLE_FEATURE_NON_POSIX_CP || (flags & FILEUTILS_INTERACTIVE)) {
300 			/*
301 			 * O_CREAT|O_EXCL: require that file did not exist before creation
302 			 */
303 			dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
304 		} else { /* POSIX, and not "cp -i" */
305 			/*
306 			 * O_CREAT|O_TRUNC: create, or truncate (security problem versus (sym)link attacks)
307 			 */
308 			dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, new_mode);
309 		}
310 		if (dst_fd == -1) {
311 			ovr = ask_and_unlink(dest, flags);
312 			if (ovr <= 0) {
313 				close(src_fd);
314 				return ovr;
315 			}
316 			/* It shouldn't exist. If it exists, do not open (symlink attack?) */
317 			dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
318 			if (dst_fd < 0) {
319 				close(src_fd);
320 				return -1;
321 			}
322 		}
323 
324 #if ENABLE_SELINUX
325 		if ((flags & (FILEUTILS_PRESERVE_SECURITY_CONTEXT|FILEUTILS_SET_SECURITY_CONTEXT))
326 		 && is_selinux_enabled() > 0
327 		) {
328 			security_context_t con;
329 			if (getfscreatecon(&con) == -1) {
330 				bb_perror_msg("getfscreatecon");
331 				return -1;
332 			}
333 			if (con) {
334 				if (setfilecon(dest, con) == -1) {
335 					bb_perror_msg("setfilecon:%s,%s", dest, con);
336 					freecon(con);
337 					return -1;
338 				}
339 				freecon(con);
340 			}
341 		}
342 #endif
343 		if (bb_copyfd_eof(src_fd, dst_fd) == -1)
344 			retval = -1;
345 		/* Careful with writing... */
346 		if (close(dst_fd) < 0) {
347 			bb_perror_msg("error writing to '%s'", dest);
348 			retval = -1;
349 		}
350 		/* ...but read size is already checked by bb_copyfd_eof */
351 		close(src_fd);
352 		/* "cp /dev/something new_file" should not
353 		 * copy mode of /dev/something */
354 		if (!S_ISREG(source_stat.st_mode))
355 			return retval;
356 		goto preserve_mode_ugid_time;
357 	}
358  dont_cat:
359 
360 	/* Source is a symlink or a special file */
361 	/* We are lazy here, a bit lax with races... */
362 	if (dest_exists) {
363 		errno = EEXIST;
364 		ovr = ask_and_unlink(dest, flags);
365 		if (ovr <= 0)
366 			return ovr;
367 	}
368 	if (S_ISLNK(source_stat.st_mode)) {
369 		char *lpath = xmalloc_readlink_or_warn(source);
370 		if (lpath) {
371 			int r = symlink(lpath, dest);
372 			free(lpath);
373 			if (r < 0) {
374 				bb_perror_msg("can't create symlink '%s'", dest);
375 				return -1;
376 			}
377 			if (flags & FILEUTILS_PRESERVE_STATUS)
378 				if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
379 					bb_perror_msg("can't preserve %s of '%s'", "ownership", dest);
380 		}
381 		/* _Not_ jumping to preserve_mode_ugid_time:
382 		 * symlinks don't have those */
383 		goto verb_and_exit;
384 	}
385 	if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
386 	 || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
387 	) {
388 		if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
389 			bb_perror_msg("can't create '%s'", dest);
390 			return -1;
391 		}
392 	} else {
393 		bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
394 		return -1;
395 	}
396 
397  preserve_mode_ugid_time:
398 
399 	if (flags & FILEUTILS_PRESERVE_STATUS
400 	/* Cannot happen: */
401 	/* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */
402 	) {
403 		struct timeval times[2];
404 
405 		times[1].tv_sec = times[0].tv_sec = source_stat.st_mtime;
406 		times[1].tv_usec = times[0].tv_usec = 0;
407 		/* BTW, utimes sets usec-precision time - just FYI */
408 		if (utimes(dest, times) < 0)
409 			bb_perror_msg("can't preserve %s of '%s'", "times", dest);
410 		if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
411 			source_stat.st_mode &= ~(S_ISUID | S_ISGID);
412 			bb_perror_msg("can't preserve %s of '%s'", "ownership", dest);
413 		}
414 		if (chmod(dest, source_stat.st_mode) < 0)
415 			bb_perror_msg("can't preserve %s of '%s'", "permissions", dest);
416 	}
417 
418  verb_and_exit:
419 	if (flags & FILEUTILS_VERBOSE) {
420 		printf("'%s' -> '%s'\n", source, dest);
421 	}
422 
423 	return retval;
424 }
425