path: root/fs/cifs/readdir.c

// SPDX-License-Identifier: LGPL-2.1
/*
 *
 *   Directory search handling
 *
 *   Copyright (C) International Business Machines  Corp., 2004, 2008
 *   Copyright (C) Red Hat, Inc., 2011
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 */
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_unicode.h"
#include "cifs_debug.h"
#include "cifs_fs_sb.h"
#include "cifsfs.h"
#include "smb2proto.h"
#include "fs_context.h"

/*
 * To be safe - for UCS to UTF-8 with strings loaded with the rare long
 * characters alloc more to account for such multibyte target UTF-8
 * characters.
 */
#define UNICODE_NAME_MAX ((4 * NAME_MAX) + 2)

#ifdef CONFIG_CIFS_DEBUG2
static void dump_cifs_file_struct(struct file *file, char *label)
{
	struct cifsFileInfo *cf;

	if (file) {
		cf = file->private_data;
		if (cf == NULL) {
			cifs_dbg(FYI, "empty cifs private file data\n");
			return;
		}
		if (cf->invalidHandle)
			cifs_dbg(FYI, "Invalid handle\n");
		if (cf->srch_inf.endOfSearch)
			cifs_dbg(FYI, "end of search\n");
		if (cf->srch_inf.emptyDir)
			cifs_dbg(FYI, "empty dir\n");
	}
}
#else
static inline void dump_cifs_file_struct(struct file *file, char *label)
{
}
#endif /* DEBUG2 */

/*
 * Attempt to preload the dcache with the results from the FIND_FIRST/NEXT
 *
 * Find the dentry that matches "name". If there isn't one, create one. If it's
 * a negative dentry or the uniqueid or filetype(mode) changed,
 * then drop it and recreate it.
 */
static void
cifs_prime_dcache(struct dentry *parent, struct qstr *name,
		    struct cifs_fattr *fattr)
{
	struct dentry *dentry, *alias;
	struct inode *inode;
	struct super_block *sb = parent->d_sb;
	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);

	cifs_dbg(FYI, "%s: for %s\n", __func__, name->name);

	dentry = d_hash_and_lookup(parent, name);
	if (!dentry) {
		/*
		 * If we know that the inode will need to be revalidated
		 * immediately, then don't create a new dentry for it.
		 * We'll end up doing an on the wire call either way and
		 * this spares us an invalidation.
		 */
		if (fattr->cf_flags & CIFS_FATTR_NEED_REVAL)
			return;
retry:
		dentry = d_alloc_parallel(parent, name, &wq);
	}
	if (IS_ERR(dentry))
		return;
	if (!d_in_lookup(dentry)) {
		inode = d_inode(dentry);
		if (inode) {
			if (d_mountpoint(dentry)) {
				dput(dentry);
				return;
			}
			/*
			 * If we're generating inode numbers, then we don't
			 * want to clobber the existing one with the one that
			 * the readdir code created.
			 */
			if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM))
				fattr->cf_uniqueid = CIFS_I(inode)->uniqueid;

			/* update inode in place
			 * if both i_ino and i_mode didn't change */
			if (CIFS_I(inode)->uniqueid == fattr->cf_uniqueid &&
			    cifs_fattr_to_inode(inode, fattr) == 0) {
				dput(dentry);
				return;
			}
		}
		d_invalidate(dentry);
		dput(dentry);
		goto retry;
	} else {
		inode = cifs_iget(sb, fattr);
		if (!inode)
			inode = ERR_PTR(-ENOMEM);
		alias = d_splice_alias(inode, dentry);
		d_lookup_done(dentry);
		if (alias && !IS_ERR(alias))
			dput(alias);
	}
	dput(dentry);
}

static bool reparse_file_needs_reval(const struct cifs_fattr *fattr)
{
	if (!(fattr->cf_cifsattrs & ATTR_REPARSE))
		return false;
	/*
	 * The DFS tags should be only intepreted by server side as per
	 * MS-FSCC 2.1.2.1, but let's include them anyway.
	 *
	 * Besides, if cf_cifstag is unset (0), then we still need it to be
	 * revalidated to know exactly what reparse point it is.
	 */
	switch (fattr->cf_cifstag) {
	case IO_REPARSE_TAG_DFS:
	case IO_REPARSE_TAG_DFSR:
	case IO_REPARSE_TAG_SYMLINK:
	case IO_REPARSE_TAG_NFS:
	case 0:
		return true;
	}
	return false;
}

static void
cifs_fill_common_info(struct cifs_fattr *fattr, struct cifs_sb_info *cifs_sb)
{
	fattr->cf_uid = cifs_sb->ctx->linux_uid;
	fattr->cf_gid = cifs_sb->ctx->linux_gid;

	/*
	 * The IO_REPARSE_TAG_LX_ tags originally were used by WSL but they
	 * are preferred by the Linux client in some cases since, unlike
	 * the NFS reparse tag (or EAs), they don't require an extra query
	 * to determine which type of special file they represent.
	 * TODO: go through all documented  reparse tags to see if we can
	 * reasonably map some of them to directories vs. files vs. symlinks
	 */
	if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
		fattr->cf_mode = S_IFDIR | cifs_sb->ctx->dir_mode;
		fattr->cf_dtype = DT_DIR;
	} else if (fattr->cf_cifstag == IO_REPARSE_TAG_LX_SYMLINK) {
		fattr->cf_mode |= S_IFLNK | cifs_sb->ctx->file_mode;
		fattr->cf_dtype = DT_LNK;
	} else if (fattr->cf_cifstag == IO_REPARSE_TAG_LX_FIFO) {
		fattr->cf_mode |= S_IFIFO | cifs_sb->ctx->file_mode;
		fattr->cf_dtype = DT_FIFO;
	} else if (fattr->cf_cifstag == IO_REPARSE_TAG_AF_UNIX) {
		fattr->cf_mode |= S_IFSOCK |