archival/libarchive/data_extract_all.c - codeaurora/busybox - Gitiles

 /* vi: set sw=4 ts=4: */
 /*
  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */

 #include "libbb.h"
 #include "bb_archive.h"

 void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
 {
 	file_header_t *file_header = archive_handle->file_header;
 	int dst_fd;
 	int res;
 	char *hard_link;
 #if ENABLE_FEATURE_TAR_LONG_OPTIONS
 	char *dst_name;
 #else
 # define dst_name (file_header->name)
 #endif

 #if ENABLE_FEATURE_TAR_SELINUX
 	char *sctx = archive_handle->tar__sctx[PAX_NEXT_FILE];
 	if (!sctx)
 		sctx = archive_handle->tar__sctx[PAX_GLOBAL];
 	if (sctx) { /* setfscreatecon is 4 syscalls, avoid if possible */
 		setfscreatecon(sctx);
 		free(archive_handle->tar__sctx[PAX_NEXT_FILE]);
 		archive_handle->tar__sctx[PAX_NEXT_FILE] = NULL;
 	}
 #endif

 	/* Hard links are encoded as regular files of size 0
 	 * with a nonempty link field */
 	hard_link = NULL;
 	if (S_ISREG(file_header->mode) && file_header->size == 0)
 		hard_link = file_header->link_target;

 #if ENABLE_FEATURE_TAR_LONG_OPTIONS
 	dst_name = file_header->name;
 	if (archive_handle->tar__strip_components) {
 		unsigned n = archive_handle->tar__strip_components;
 		do {
 			dst_name = strchr(dst_name, '/');
 			if (!dst_name || dst_name[1] == '\0') {
 				data_skip(archive_handle);
 				goto ret;
 			}
 			dst_name++;
 			/*
 			 * Link target is shortened only for hardlinks:
 			 * softlinks restored unchanged.
 			 */
 			if (hard_link) {
 // GNU tar 1.26 does not check that we reached end of link name:
 // if "dir/hardlink" is hardlinked to "file",
 // tar xvf a.tar --strip-components=1 says:
 //  tar: hardlink: Cannot hard link to '': No such file or directory
 // and continues processing. We silently skip such entries.
 				hard_link = strchr(hard_link, '/');
 				if (!hard_link || hard_link[1] == '\0') {
 					data_skip(archive_handle);
 					goto ret;
 				}
 				hard_link++;
 			}
 		} while (--n != 0);
 	}
 #endif

 	if (archive_handle->ah_flags & ARCHIVE_CREATE_LEADING_DIRS) {
 		char *slash = strrchr(dst_name, '/');
 		if (slash) {
 			*slash = '\0';
 			bb_make_directory(dst_name, -1, FILEUTILS_RECUR);
 			*slash = '/';
 		}
 	}

 	if (archive_handle->ah_flags & ARCHIVE_UNLINK_OLD) {
 		/* Remove the entry if it exists */
 		if (!S_ISDIR(file_header->mode)) {
 			if (hard_link) {
 				/* Ugly special case:
 				 * tar cf t.tar hardlink1 hardlink2 hardlink1
 				 * results in this tarball structure:
 				 * hardlink1
 				 * hardlink2 -> hardlink1
 				 * hardlink1 -> hardlink1 <== !!!
 				 */
 				if (strcmp(hard_link, dst_name) == 0)
 					goto ret;
 			}
 			/* Proceed with deleting */
 			if (unlink(dst_name) == -1
 			 && errno != ENOENT
 			) {
 				bb_perror_msg_and_die("can't remove old file %s",
 						dst_name);
 			}
 		}
 	}
 	else if (archive_handle->ah_flags & ARCHIVE_EXTRACT_NEWER) {
 		/* Remove the existing entry if its older than the extracted entry */
 		struct stat existing_sb;
 		if (lstat(dst_name, &existing_sb) == -1) {
 			if (errno != ENOENT) {
 				bb_perror_msg_and_die("can't stat old file");
 			}
 		}
 		else if (existing_sb.st_mtime >= file_header->mtime) {
 			if (!(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
 			 && !S_ISDIR(file_header->mode)
 			) {
 				bb_error_msg("%s not created: newer or "
 					"same age file exists", dst_name);
 			}
 			data_skip(archive_handle);
 			goto ret;
 		}
 		else if ((unlink(dst_name) == -1) && (errno != EISDIR)) {
 			bb_perror_msg_and_die("can't remove old file %s",
 					dst_name);
 		}
 	}

 	/* Handle hard links separately */
 	if (hard_link) {
 		res = link(hard_link, dst_name);
 		if (res != 0 && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)) {
 			/* shared message */
 			bb_perror_msg("can't create %slink '%s' to '%s'",
 					"hard",
 					dst_name,
 					hard_link
 			);
 		}
 		/* Hardlinks have no separate mode/ownership, skip chown/chmod */
 		goto ret;
 	}

 	/* Create the filesystem entry */
 	switch (file_header->mode & S_IFMT) {
 	case S_IFREG: {
 		/* Regular file */
 		char *dst_nameN;
 		int flags = O_WRONLY | O_CREAT | O_EXCL;
 		if (archive_handle->ah_flags & ARCHIVE_O_TRUNC)
 			flags = O_WRONLY | O_CREAT | O_TRUNC;
 		dst_nameN = dst_name;
 #ifdef ARCHIVE_REPLACE_VIA_RENAME
 		if (archive_handle->ah_flags & ARCHIVE_REPLACE_VIA_RENAME)
 			/* rpm-style temp file name */
 			dst_nameN = xasprintf("%s;%x", dst_name, (int)getpid());
 #endif
 		dst_fd = xopen3(dst_nameN,
 			flags,
 			file_header->mode
 			);
 		bb_copyfd_exact_size(archive_handle->src_fd, dst_fd, file_header->size);
 		close(dst_fd);
 #ifdef ARCHIVE_REPLACE_VIA_RENAME
 		if (archive_handle->ah_flags & ARCHIVE_REPLACE_VIA_RENAME) {
 			xrename(dst_nameN, dst_name);
 			free(dst_nameN);
 		}
 #endif
 		break;
 	}
 	case S_IFDIR:
 		res = mkdir(dst_name, file_header->mode);
 		if ((res == -1)
 		 && (errno != EISDIR) /* btw, Linux doesn't return this */
 		 && (errno != EEXIST)
 		 && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
 		) {
 			bb_perror_msg("can't make dir %s", dst_name);
 		}
 		break;
 	case S_IFLNK:
 		/* Symlink */
 //TODO: what if file_header->link_target == NULL (say, corrupted tarball?)

 		/* To avoid a directory traversal attack via symlinks,
 		 * for certain link targets postpone creation of symlinks.
 		 *
 		 * For example, consider a .tar created via:
 		 *  $ tar cvf bug.tar anything.txt
 		 *  $ ln -s /tmp symlink
 		 *  $ tar --append -f bug.tar symlink
 		 *  $ rm symlink
 		 *  $ mkdir symlink
 		 *  $ tar --append -f bug.tar symlink/evil.py
 		 *
 		 * This will result in an archive that contains:
 		 *  $ tar --list -f bug.tar
 		 *  anything.txt
 		 *  symlink [-> /tmp]
 		 *  symlink/evil.py
 		 *
 		 * Untarring bug.tar would otherwise place evil.py in '/tmp'.
 		 */
 		if (file_header->link_target[0] == '/'
 		 || strstr(file_header->link_target, "..")
 		) {
 			llist_add_to(&archive_handle->symlink_placeholders,
 				xasprintf("%s%c%s", file_header->name, '\0', file_header->link_target)
 			);
 			break;
 		}
 		res = symlink(file_header->link_target, dst_name);
 		if (res != 0
 		 && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
 		) {
 			/* shared message */
 			bb_perror_msg("can't create %slink '%s' to '%s'",
 				"sym",
 				dst_name,
 				file_header->link_target
 			);
 		}
 		break;
 	case S_IFSOCK:
 	case S_IFBLK:
 	case S_IFCHR:
 	case S_IFIFO:
 		res = mknod(dst_name, file_header->mode, file_header->device);
 		if ((res == -1)
 		 && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
 		) {
 			bb_perror_msg("can't create node %s", dst_name);
 		}
 		break;
 	default:
 		bb_error_msg_and_die("unrecognized file type");
 	}

 	if (!S_ISLNK(file_header->mode)) {
 		if (!(archive_handle->ah_flags & ARCHIVE_DONT_RESTORE_OWNER)) {
 			uid_t uid = file_header->uid;
 			gid_t gid = file_header->gid;
 #if ENABLE_FEATURE_TAR_UNAME_GNAME
 			if (!(archive_handle->ah_flags & ARCHIVE_NUMERIC_OWNER)) {
 				if (file_header->tar__uname) {
 //TODO: cache last name/id pair?
 					struct passwd *pwd = getpwnam(file_header->tar__uname);
 					if (pwd) uid = pwd->pw_uid;
 				}
 				if (file_header->tar__gname) {
 					struct group *grp = getgrnam(file_header->tar__gname);
 					if (grp) gid = grp->gr_gid;
 				}
 			}
 #endif
 			/* GNU tar 1.15.1 uses chown, not lchown */
 			chown(dst_name, uid, gid);
 		}
 		/* uclibc has no lchmod, glibc is even stranger -
 		 * it has lchmod which seems to do nothing!
 		 * so we use chmod... */
 		if (!(archive_handle->ah_flags & ARCHIVE_DONT_RESTORE_PERM)) {
 			chmod(dst_name, file_header->mode);
 		}
 		if (archive_handle->ah_flags & ARCHIVE_RESTORE_DATE) {
 			struct timeval t[2];

 			t[1].tv_sec = t[0].tv_sec = file_header->mtime;
 			t[1].tv_usec = t[0].tv_usec = 0;
 			utimes(dst_name, t);
 		}
 	}

  ret: ;
 #if ENABLE_FEATURE_TAR_SELINUX
 	if (sctx) {
 		/* reset the context after creating an entry */
 		setfscreatecon(NULL);
 	}
 #endif
 }
	/* vi: set sw=4 ts=4: */
	/*
	* Licensed under GPLv2 or later, see file LICENSE in this source tree.
	*/

	#include "libbb.h"
	#include "bb_archive.h"

	void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
	{
	file_header_t *file_header = archive_handle->file_header;
	int dst_fd;
	int res;
	char *hard_link;
	#if ENABLE_FEATURE_TAR_LONG_OPTIONS
	char *dst_name;
	#else
	# define dst_name (file_header->name)
	#endif

	#if ENABLE_FEATURE_TAR_SELINUX
	char *sctx = archive_handle->tar__sctx[PAX_NEXT_FILE];
	if (!sctx)
	sctx = archive_handle->tar__sctx[PAX_GLOBAL];
	if (sctx) { /* setfscreatecon is 4 syscalls, avoid if possible */
	setfscreatecon(sctx);
	free(archive_handle->tar__sctx[PAX_NEXT_FILE]);
	archive_handle->tar__sctx[PAX_NEXT_FILE] = NULL;
	}
	#endif

	/* Hard links are encoded as regular files of size 0
	* with a nonempty link field */
	hard_link = NULL;
	if (S_ISREG(file_header->mode) && file_header->size == 0)
	hard_link = file_header->link_target;

	#if ENABLE_FEATURE_TAR_LONG_OPTIONS
	dst_name = file_header->name;
	if (archive_handle->tar__strip_components) {
	unsigned n = archive_handle->tar__strip_components;
	do {
	dst_name = strchr(dst_name, '/');
	if (!dst_name \|\| dst_name[1] == '\0') {
	data_skip(archive_handle);
	goto ret;
	}
	dst_name++;
	/*
	* Link target is shortened only for hardlinks:
	* softlinks restored unchanged.
	*/
	if (hard_link) {
	// GNU tar 1.26 does not check that we reached end of link name:
	// if "dir/hardlink" is hardlinked to "file",
	// tar xvf a.tar --strip-components=1 says:
	// tar: hardlink: Cannot hard link to '': No such file or directory
	// and continues processing. We silently skip such entries.
	hard_link = strchr(hard_link, '/');
	if (!hard_link \|\| hard_link[1] == '\0') {
	data_skip(archive_handle);
	goto ret;
	}
	hard_link++;
	}
	} while (--n != 0);
	}
	#endif

	if (archive_handle->ah_flags & ARCHIVE_CREATE_LEADING_DIRS) {
	char *slash = strrchr(dst_name, '/');
	if (slash) {
	*slash = '\0';
	bb_make_directory(dst_name, -1, FILEUTILS_RECUR);
	*slash = '/';
	}
	}

	if (archive_handle->ah_flags & ARCHIVE_UNLINK_OLD) {
	/* Remove the entry if it exists */
	if (!S_ISDIR(file_header->mode)) {
	if (hard_link) {
	/* Ugly special case:
	* tar cf t.tar hardlink1 hardlink2 hardlink1
	* results in this tarball structure:
	* hardlink1
	* hardlink2 -> hardlink1
	* hardlink1 -> hardlink1 <== !!!
	*/
	if (strcmp(hard_link, dst_name) == 0)
	goto ret;
	}
	/* Proceed with deleting */
	if (unlink(dst_name) == -1
	&& errno != ENOENT
	) {
	bb_perror_msg_and_die("can't remove old file %s",
	dst_name);
	}
	}
	}
	else if (archive_handle->ah_flags & ARCHIVE_EXTRACT_NEWER) {
	/* Remove the existing entry if its older than the extracted entry */
	struct stat existing_sb;
	if (lstat(dst_name, &existing_sb) == -1) {
	if (errno != ENOENT) {
	bb_perror_msg_and_die("can't stat old file");
	}
	}
	else if (existing_sb.st_mtime >= file_header->mtime) {
	if (!(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
	&& !S_ISDIR(file_header->mode)
	) {
	bb_error_msg("%s not created: newer or "
	"same age file exists", dst_name);
	}
	data_skip(archive_handle);
	goto ret;
	}
	else if ((unlink(dst_name) == -1) && (errno != EISDIR)) {
	bb_perror_msg_and_die("can't remove old file %s",
	dst_name);
	}
	}

	/* Handle hard links separately */
	if (hard_link) {
	res = link(hard_link, dst_name);
	if (res != 0 && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)) {
	/* shared message */
	bb_perror_msg("can't create %slink '%s' to '%s'",
	"hard",
	dst_name,
	hard_link
	);
	}
	/* Hardlinks have no separate mode/ownership, skip chown/chmod */
	goto ret;
	}

	/* Create the filesystem entry */
	switch (file_header->mode & S_IFMT) {
	case S_IFREG: {
	/* Regular file */
	char *dst_nameN;
	int flags = O_WRONLY \| O_CREAT \| O_EXCL;
	if (archive_handle->ah_flags & ARCHIVE_O_TRUNC)
	flags = O_WRONLY \| O_CREAT \| O_TRUNC;
	dst_nameN = dst_name;
	#ifdef ARCHIVE_REPLACE_VIA_RENAME
	if (archive_handle->ah_flags & ARCHIVE_REPLACE_VIA_RENAME)
	/* rpm-style temp file name */
	dst_nameN = xasprintf("%s;%x", dst_name, (int)getpid());
	#endif
	dst_fd = xopen3(dst_nameN,
	flags,
	file_header->mode
	);
	bb_copyfd_exact_size(archive_handle->src_fd, dst_fd, file_header->size);
	close(dst_fd);
	#ifdef ARCHIVE_REPLACE_VIA_RENAME
	if (archive_handle->ah_flags & ARCHIVE_REPLACE_VIA_RENAME) {
	xrename(dst_nameN, dst_name);
	free(dst_nameN);
	}
	#endif
	break;
	}
	case S_IFDIR:
	res = mkdir(dst_name, file_header->mode);
	if ((res == -1)
	&& (errno != EISDIR) /* btw, Linux doesn't return this */
	&& (errno != EEXIST)
	&& !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
	) {
	bb_perror_msg("can't make dir %s", dst_name);
	}
	break;
	case S_IFLNK:
	/* Symlink */
	//TODO: what if file_header->link_target == NULL (say, corrupted tarball?)

	/* To avoid a directory traversal attack via symlinks,
	* for certain link targets postpone creation of symlinks.
	*
	* For example, consider a .tar created via:
	* $ tar cvf bug.tar anything.txt
	* $ ln -s /tmp symlink
	* $ tar --append -f bug.tar symlink
	* $ rm symlink
	* $ mkdir symlink
	* $ tar --append -f bug.tar symlink/evil.py
	*
	* This will result in an archive that contains:
	* $ tar --list -f bug.tar
	* anything.txt
	* symlink [-> /tmp]
	* symlink/evil.py
	*
	* Untarring bug.tar would otherwise place evil.py in '/tmp'.
	*/
	if (file_header->link_target[0] == '/'
	\|\| strstr(file_header->link_target, "..")
	) {
	llist_add_to(&archive_handle->symlink_placeholders,
	xasprintf("%s%c%s", file_header->name, '\0', file_header->link_target)
	);
	break;
	}
	res = symlink(file_header->link_target, dst_name);
	if (res != 0
	&& !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
	) {
	/* shared message */
	bb_perror_msg("can't create %slink '%s' to '%s'",
	"sym",
	dst_name,
	file_header->link_target
	);
	}
	break;
	case S_IFSOCK:
	case S_IFBLK:
	case S_IFCHR:
	case S_IFIFO:
	res = mknod(dst_name, file_header->mode, file_header->device);
	if ((res == -1)
	&& !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
	) {
	bb_perror_msg("can't create node %s", dst_name);
	}
	break;
	default:
	bb_error_msg_and_die("unrecognized file type");
	}

	if (!S_ISLNK(file_header->mode)) {
	if (!(archive_handle->ah_flags & ARCHIVE_DONT_RESTORE_OWNER)) {
	uid_t uid = file_header->uid;
	gid_t gid = file_header->gid;
	#if ENABLE_FEATURE_TAR_UNAME_GNAME
	if (!(archive_handle->ah_flags & ARCHIVE_NUMERIC_OWNER)) {
	if (file_header->tar__uname) {
	//TODO: cache last name/id pair?
	struct passwd *pwd = getpwnam(file_header->tar__uname);
	if (pwd) uid = pwd->pw_uid;
	}
	if (file_header->tar__gname) {
	struct group *grp = getgrnam(file_header->tar__gname);
	if (grp) gid = grp->gr_gid;
	}
	}
	#endif
	/* GNU tar 1.15.1 uses chown, not lchown */
	chown(dst_name, uid, gid);
	}
	/* uclibc has no lchmod, glibc is even stranger -
	* it has lchmod which seems to do nothing!
	* so we use chmod... */
	if (!(archive_handle->ah_flags & ARCHIVE_DONT_RESTORE_PERM)) {
	chmod(dst_name, file_header->mode);
	}
	if (archive_handle->ah_flags & ARCHIVE_RESTORE_DATE) {
	struct timeval t[2];

	t[1].tv_sec = t[0].tv_sec = file_header->mtime;
	t[1].tv_usec = t[0].tv_usec = 0;
	utimes(dst_name, t);
	}
	}

	ret: ;
	#if ENABLE_FEATURE_TAR_SELINUX
	if (sctx) {
	/* reset the context after creating an entry */
	setfscreatecon(NULL);
	}
	#endif
	}