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, &times) < 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