busybox/libbb/copy_file.c
Denis Vlasenko 54d14ca1a2 copy_file: comment out one condition which is always false.
Add comment explaining POSIX rules for cp - and why
these rules are dangerous. Provide conditionally compiled code
for both POSIX and safe behaviors, select safe for now.
Code shrunk by ~80 bytes.
2007-03-15 13:33:37 +00:00

344 lines
9.0 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Mini copy_file implementation for busybox
*
* Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
* SELinux support by Yuichi Nakamura <ynakam@hitachisoft.jp>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*
*/
#include "libbb.h"
// POSIX: if exists and -i, ask (w/o -i assume yes).
// Then open w/o EXCL (yes, not unlink!).
// If open still fails and -f, try unlink, then try open again.
// Result: a mess:
// If dest is a softlink, we overwrite softlink's destination!
// (or fail, if it points to dir/nonexistent location/etc).
// This is strange, but POSIX-correct.
// coreutils cp has --remove-destination to override this...
#define DO_POSIX_CP 0 /* 1 - POSIX behavior, 0 - safe behavior */
static int ask_and_unlink(const char *dest, int flags)
{
// If !DO_POSIX_CP, act as if -f is always in effect - we don't want
// "'file' exists" msg, we want unlink to be done (silently unless -i
// is also in effect).
// This prevents safe way from asking more questions than POSIX does.
#if DO_POSIX_CP
if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) {
fprintf(stderr, "'%s' exists\n", dest);
return -1;
}
#endif
// TODO: maybe we should do it only if ctty is present?
if (flags & FILEUTILS_INTERACTIVE) {
// We would not do POSIX insanity. -i asks,
// then _unlinks_ the offender. Presto.
// (No opening without O_EXCL, no unlinks only if -f)
// Or else we will end up having 3 open()s!
fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest);
if (!bb_ask_confirmation())
return 0; // not allowed to overwrite
}
if (unlink(dest) < 0) {
bb_perror_msg("cannot remove '%s'", dest);
return -1; // error
}
return 1; // ok (to try again)
}
/* Return:
* -1 error, copy not made
* 0 copy is made or user answered "no" in interactive mode
* (failures to preserve mode/owner/times are not reported in exit code)
*/
int copy_file(const char *source, const char *dest, int flags)
{
struct stat source_stat;
struct stat dest_stat;
int status = 0;
signed char dest_exists = 0;
signed char ovr;
#define FLAGS_DEREF (flags & FILEUTILS_DEREFERENCE)
if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
// This may be a dangling symlink.
// Making [sym]links to dangling symlinks works, so...
if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK))
goto make_links;
bb_perror_msg("cannot stat '%s'", source);
return -1;
}
if (lstat(dest, &dest_stat) < 0) {
if (errno != ENOENT) {
bb_perror_msg("cannot stat '%s'", dest);
return -1;
}
} else {
if (source_stat.st_dev == dest_stat.st_dev
&& source_stat.st_ino == dest_stat.st_ino
) {
bb_error_msg("'%s' and '%s' are the same file", source, dest);
return -1;
}
dest_exists = 1;
}
#if ENABLE_SELINUX
if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) {
security_context_t con;
if (lgetfilecon(source, &con) >= 0) {
if (setfscreatecon(con) < 0) {
bb_perror_msg("cannot set setfscreatecon %s", con);
freecon(con);
return -1;
}
} else if (errno == ENOTSUP || errno == ENODATA) {
setfscreatecon_or_die(NULL);
} else {
bb_perror_msg("cannot lgetfilecon %s", source);
return -1;
}
}
#endif
if (S_ISDIR(source_stat.st_mode)) {
DIR *dp;
struct dirent *d;
mode_t saved_umask = 0;
if (!(flags & FILEUTILS_RECUR)) {
bb_error_msg("omitting directory '%s'", source);
return -1;
}
/* Create DEST. */
if (dest_exists) {
if (!S_ISDIR(dest_stat.st_mode)) {
bb_error_msg("target '%s' is not a directory", dest);
return -1;
}
} else {
mode_t mode;
saved_umask = umask(0);
mode = source_stat.st_mode;
if (!(flags & FILEUTILS_PRESERVE_STATUS))
mode = source_stat.st_mode & ~saved_umask;
mode |= S_IRWXU;
if (mkdir(dest, mode) < 0) {
umask(saved_umask);
bb_perror_msg("cannot create directory '%s'", dest);
return -1;
}
umask(saved_umask);
}
/* Recursively copy files in SOURCE. */
dp = opendir(source);
if (dp == NULL) {
status = -1;
goto preserve_status;
}
while ((d = readdir(dp)) != NULL) {
char *new_source, *new_dest;
new_source = concat_subpath_file(source, d->d_name);
if (new_source == NULL)
continue;
new_dest = concat_path_file(dest, d->d_name);
if (copy_file(new_source, new_dest, flags) < 0)
status = -1;
free(new_source);
free(new_dest);
}
closedir(dp);
if (!dest_exists
&& chmod(dest, source_stat.st_mode & ~saved_umask) < 0
) {
bb_perror_msg("cannot change permissions of '%s'", dest);
status = -1;
}
} else if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
int (*lf)(const char *oldpath, const char *newpath);
make_links:
// Hmm... maybe
// if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
// (but realpath returns NULL on dangling symlinks...)
lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
if (lf(source, dest) < 0) {
ovr = ask_and_unlink(dest, flags);
if (ovr <= 0)
return ovr;
if (lf(source, dest) < 0) {
bb_perror_msg("cannot create link '%s'", dest);
return -1;
}
}
return 0;
} else if (S_ISREG(source_stat.st_mode)
/* Huh? DEREF uses stat, which never returns links! */
/* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
) {
int src_fd;
int dst_fd;
if (ENABLE_FEATURE_PRESERVE_HARDLINKS) {
char *link_name;
if (!FLAGS_DEREF) {
link_name = is_in_ino_dev_hashtable(&source_stat);
if (link_name) {
if (link(link_name, dest) < 0) {
ovr = ask_and_unlink(dest, flags);
if (ovr <= 0)
return ovr;
if (link(link_name, dest) < 0) {
bb_perror_msg("cannot create link '%s'", dest);
return -1;
}
}
return 0;
}
}
add_to_ino_dev_hashtable(&source_stat, dest);
}
src_fd = open(source, O_RDONLY);
if (src_fd == -1) {
bb_perror_msg("cannot open '%s'", source);
return -1;
}
#if DO_POSIX_CP /* POSIX way (a security problem versus symlink attacks!): */
dst_fd = open(dest, (flags & FILEUTILS_INTERACTIVE)
? O_WRONLY|O_CREAT|O_EXCL
: O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode);
#else /* safe way: */
dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode);
#endif
if (dst_fd == -1) {
ovr = ask_and_unlink(dest, flags);
if (ovr <= 0) {
close(src_fd);
return ovr;
}
/* It shouldn't exist. If it exists, do not open (symlink attack?) */
dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode);
if (dst_fd == -1) {
bb_perror_msg("cannot open '%s'", dest);
close(src_fd);
return -1;
}
}
#if ENABLE_SELINUX
if (((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT)
|| (flags & FILEUTILS_SET_SECURITY_CONTEXT))
&& is_selinux_enabled() > 0
) {
security_context_t con;
if (getfscreatecon(&con) == -1) {
bb_perror_msg("getfscreatecon");
return -1;
}
if (con) {
if(setfilecon(dest, con) == -1) {
bb_perror_msg("setfilecon:%s,%s", dest, con);
freecon(con);
return -1;
}
freecon(con);
}
}
#endif
if (bb_copyfd_eof(src_fd, dst_fd) == -1)
status = -1;
if (close(dst_fd) < 0) {
bb_perror_msg("cannot close '%s'", dest);
status = -1;
}
if (close(src_fd) < 0) {
bb_perror_msg("cannot close '%s'", source);
status = -1;
}
} else if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
|| S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
|| S_ISLNK(source_stat.st_mode)
) {
// We are lazy here, a bit lax with races...
if (dest_exists) {
ovr = ask_and_unlink(dest, flags);
if (ovr <= 0)
return ovr;
}
if (S_ISFIFO(source_stat.st_mode)) {
if (mkfifo(dest, source_stat.st_mode) < 0) {
bb_perror_msg("cannot create fifo '%s'", dest);
return -1;
}
} else if (S_ISLNK(source_stat.st_mode)) {
char *lpath;
lpath = xmalloc_readlink_or_warn(source);
if (lpath && symlink(lpath, dest) < 0) {
bb_perror_msg("cannot create symlink '%s'", dest);
free(lpath);
return -1;
}
free(lpath);
if (flags & FILEUTILS_PRESERVE_STATUS)
if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
return 0;
} else {
if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
bb_perror_msg("cannot create '%s'", dest);
return -1;
}
}
} else {
bb_error_msg("internal error: unrecognized file type");
return -1;
}
preserve_status:
if (flags & FILEUTILS_PRESERVE_STATUS
/* Cannot happen: */
/* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */
) {
struct utimbuf times;
times.actime = source_stat.st_atime;
times.modtime = source_stat.st_mtime;
if (utime(dest, &times) < 0)
bb_perror_msg("cannot preserve %s of '%s'", "times", dest);
if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
source_stat.st_mode &= ~(S_ISUID | S_ISGID);
bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
}
if (chmod(dest, source_stat.st_mode) < 0)
bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
}
return status;
}