// SPDX-License-Identifier: GPL-2.0/* *  linux/fs/ext4/dir.c * * Copyright (C) 1992, 1993, 1994, 1995 * Remy Card (card@masi.ibp.fr) * Laboratoire MASI - Institut Blaise Pascal * Universite Pierre et Marie Curie (Paris VI) * *  from * *  linux/fs/minix/dir.c * *  Copyright (C) 1991, 1992  Linus Torvalds * *  ext4 directory handling functions * *  Big-endian to little-endian byte-swapping/bitmaps by *        David S. Miller (davem@caip.rutgers.edu), 1995 * * Hash Tree Directory indexing (c) 2001  Daniel Phillips * */ #include <linux/fs.h>#include <linux/buffer_head.h>#include <linux/slab.h>#include <linux/iversion.h>#include <linux/unicode.h>#include "ext4.h"#include "xattr.h" static int ext4_dx_readdir(struct file *, struct dir_context *); /** * is_dx_dir() - check if a directory is using htree indexing * @inode: directory inode * * Check if the given dir-inode refers to an htree-indexed directory * (or a directory which could potentially get converted to use htree * indexing). * * Return 1 if it is a dx dir, 0 if not */static int is_dx_dir(struct inode *inode){	struct super_block *sb = inode->i_sb; 	if (ext4_has_feature_dir_index(inode->i_sb) &&	    ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||	     ((inode->i_size >> sb->s_blocksize_bits) == 1) ||	     ext4_has_inline_data(inode)))		return 1; 	return 0;} /* * Return 0 if the directory entry is OK, and 1 if there is a problem * * Note: this is the opposite of what ext2 and ext3 historically returned... * * bh passed here can be an inode block or a dir data block, depending * on the inode inline data flag. */int __ext4_check_dir_entry(const char *function, unsigned int line,			   struct inode *dir, struct file *filp,			   struct ext4_dir_entry_2 *de,			   struct buffer_head *bh, char *buf, int size,			   unsigned int offset){	const char *error_msg = NULL;	const int rlen = ext4_rec_len_from_disk(de->rec_len,						dir->i_sb->s_blocksize);	const int next_offset = ((char *) de - buf) + rlen; 	if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))		error_msg = "rec_len is smaller than minimal";	else if (unlikely(rlen % 4 != 0))		error_msg = "rec_len % 4 != 0";	else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))		error_msg = "rec_len is too small for name_len";	else if (unlikely(next_offset > size))		error_msg = "directory entry overrun";	else if (unlikely(next_offset > size - EXT4_DIR_REC_LEN(1) &&			  next_offset != size))		error_msg = "directory entry too close to block end";	else if (unlikely(le32_to_cpu(de->inode) >			le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))		error_msg = "inode out of bounds";	else		return 0; 	if (filp)		ext4_error_file(filp, function, line, bh->b_blocknr,				"bad entry in directory: %s - offset=%u, "				"inode=%u, rec_len=%d, name_len=%d, size=%d",				error_msg, offset, le32_to_cpu(de->inode),				rlen, de->name_len, size);	else		ext4_error_inode(dir, function, line, bh->b_blocknr,				"bad entry in directory: %s - offset=%u, "				"inode=%u, rec_len=%d, name_len=%d, size=%d",				 error_msg, offset, le32_to_cpu(de->inode),				 rlen, de->name_len, size); 	return 1;} static int ext4_readdir(struct file *file, struct dir_context *ctx){	unsigned int offset;	int i;	struct ext4_dir_entry_2 *de;	int err;	struct inode *inode = file_inode(file);	struct super_block *sb = inode->i_sb;	struct buffer_head *bh = NULL;	struct fscrypt_str fstr = FSTR_INIT(NULL, 0); 	if (IS_ENCRYPTED(inode)) {		err = fscrypt_get_encryption_info(inode);		if (err)			return err;	} 	if (is_dx_dir(inode)) {		err = ext4_dx_readdir(file, ctx);		if (err != ERR_BAD_DX_DIR) {			return err;		}		/* Can we just clear INDEX flag to ignore htree information? */		if (!ext4_has_metadata_csum(sb)) {			/*			 * We don't set the inode dirty flag since it's not			 * critical that it gets flushed back to the disk.			 */			ext4_clear_inode_flag(inode, EXT4_INODE_INDEX);		}	} 	if (ext4_has_inline_data(inode)) {		int has_inline_data = 1;		err = ext4_read_inline_dir(file, ctx,					   &has_inline_data);		if (has_inline_data)			return err;	} 	if (IS_ENCRYPTED(inode)) {		err = fscrypt_fname_alloc_buffer(inode, EXT4_NAME_LEN, &fstr);		if (err < 0)			return err;	} 	while (ctx->pos < inode->i_size) {		struct ext4_map_blocks map; 		if (fatal_signal_pending(current)) {			err = -ERESTARTSYS;			goto errout;		}		cond_resched();		offset = ctx->pos & (sb->s_blocksize - 1);		map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);		map.m_len = 1;		err = ext4_map_blocks(NULL, inode, &map, 0);		if (err == 0) {			/* m_len should never be zero but let's avoid			 * an infinite loop if it somehow is */			if (map.m_len == 0)				map.m_len = 1;			ctx->pos += map.m_len * sb->s_blocksize;			continue;		}		if (err > 0) {			pgoff_t index = map.m_pblk >>					(PAGE_SHIFT - inode->i_blkbits);			if (!ra_has_index(&file->f_ra, index))				page_cache_sync_readahead(					sb->s_bdev->bd_inode->i_mapping,					&file->f_ra, file,					index, 1);			file->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT;			bh = ext4_bread(NULL, inode, map.m_lblk, 0);			if (IS_ERR(bh)) {				err = PTR_ERR(bh);				bh = NULL;				goto errout;			}		} 		if (!bh) {			/* corrupt size?  Maybe no more blocks to read */			if (ctx->pos > inode->i_blocks << 9)				break;			ctx->pos += sb->s_blocksize - offset;			continue;		} 		/* Check the checksum */		if (!buffer_verified(bh) &&		    !ext4_dirblock_csum_verify(inode, bh)) {			EXT4_ERROR_FILE(file, 0, "directory fails checksum "					"at offset %llu",					(unsigned long long)ctx->pos);			ctx->pos += sb->s_blocksize - offset;			brelse(bh);			bh = NULL;			continue;		}		set_buffer_verified(bh); 		/* If the dir block has changed since the last call to		 * readdir(2), then we might be pointing to an invalid		 * dirent right now.  Scan from the start of the block		 * to make sure. */		if (!inode_eq_iversion(inode, file->f_version)) {			for (i = 0; i < sb->s_blocksize && i < offset; ) {				de = (struct ext4_dir_entry_2 *)					(bh->b_data + i);				/* It's too expensive to do a full				 * dirent test each time round this				 * loop, but we do have to test at				 * least that it is non-zero.  A				 * failure will be detected in the				 * dirent test below. */				if (ext4_rec_len_from_disk(de->rec_len,					sb->s_blocksize) < EXT4_DIR_REC_LEN(1))					break;				i += ext4_rec_len_from_disk(de->rec_len,							    sb->s_blocksize);			}			offset = i;			ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))				| offset;			file->f_version = inode_query_iversion(inode);		} 		while (ctx->pos < inode->i_size		       && offset < sb->s_blocksize) {			de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);			if (ext4_check_dir_entry(inode, file, de, bh,						 bh->b_data, bh->b_size,						 offset)) {				/*				 * On error, skip to the next block				 */				ctx->pos = (ctx->pos |						(sb->s_blocksize - 1)) + 1;				break;			}			offset += ext4_rec_len_from_disk(de->rec_len,					sb->s_blocksize);			if (le32_to_cpu(de->inode)) {				if (!IS_ENCRYPTED(inode)) {					if (!dir_emit(ctx, de->name,					    de->name_len,					    le32_to_cpu(de->inode),					    get_dtype(sb, de->file_type)))						goto done;				} else {					int save_len = fstr.len;					struct fscrypt_str de_name =							FSTR_INIT(de->name,								de->name_len); 					/* Directory is encrypted */					err = fscrypt_fname_disk_to_usr(inode,						0, 0, &de_name, &fstr);					de_name = fstr;					fstr.len = save_len;					if (err)						goto errout;					if (!dir_emit(ctx,					    de_name.name, de_name.len,					    le32_to_cpu(de->inode),					    get_dtype(sb, de->file_type)))						goto done;				}			}			ctx->pos += ext4_rec_len_from_disk(de->rec_len,						sb->s_blocksize);		}		if ((ctx->pos < inode->i_size) && !dir_relax_shared(inode))			goto done;		brelse(bh);		bh = NULL;		offset = 0;	}done:	err = 0;errout:	fscrypt_fname_free_buffer(&fstr);	brelse(bh);	return err;} static inline int is_32bit_api(void){#ifdef CONFIG_COMPAT	return in_compat_syscall();#else	return (BITS_PER_LONG == 32);#endif} /* * These functions convert from the major/minor hash to an f_pos * value for dx directories * * Upper layer (for example NFS) should specify FMODE_32BITHASH or * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted * directly on both 32-bit and 64-bit nodes, under such case, neither * FMODE_32BITHASH nor FMODE_64BITHASH is specified. */static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor){	if ((filp->f_mode & FMODE_32BITHASH) ||	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))		return major >> 1;	else		return ((__u64)(major >> 1) << 32) | (__u64)minor;} static inline __u32 pos2maj_hash(struct file *filp, loff_t pos){	if ((filp->f_mode & FMODE_32BITHASH) ||	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))		return (pos << 1) & 0xffffffff;	else		return ((pos >> 32) << 1) & 0xffffffff;} static inline __u32 pos2min_hash(struct file *filp, loff_t pos){	if ((filp->f_mode & FMODE_32BITHASH) ||	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))		return 0;	else		return pos & 0xffffffff;} /* * Return 32- or 64-bit end-of-file for dx directories */static inline loff_t ext4_get_htree_eof(struct file *filp){	if ((filp->f_mode & FMODE_32BITHASH) ||	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))		return EXT4_HTREE_EOF_32BIT;	else		return EXT4_HTREE_EOF_64BIT;}  /* * ext4_dir_llseek() calls generic_file_llseek_size to handle htree * directories, where the "offset" is in terms of the filename hash * value instead of the byte offset. * * Because we may return a 64-bit hash that is well beyond offset limits, * we need to pass the max hash as the maximum allowable offset in * the htree directory case. * * For non-htree, ext4_llseek already chooses the proper max offset. */static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence){	struct inode *inode = file->f_mapping->host;	int dx_dir = is_dx_dir(inode);	loff_t ret, htree_max = ext4_get_htree_eof(file); 	if (likely(dx_dir))		ret = generic_file_llseek_size(file, offset, whence,						    htree_max, htree_max);	else		ret = ext4_llseek(file, offset, whence);	file->f_version = inode_peek_iversion(inode) - 1;	return ret;} /* * This structure holds the nodes of the red-black tree used to store * the directory entry in hash order. */struct fname {	__u32		hash;	__u32		minor_hash;	struct rb_node	rb_hash;	struct fname	*next;	__u32		inode;	__u8		name_len;	__u8		file_type;	char		name[];}; /* * This functoin implements a non-recursive way of freeing all of the * nodes in the red-black tree. */static void free_rb_tree_fname(struct rb_root *root){	struct fname *fname, *next; 	rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)		while (fname) {			struct fname *old = fname;			fname = fname->next;			kfree(old);		} 	*root = RB_ROOT;}  static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,							   loff_t pos){	struct dir_private_info *p; 	p = kzalloc(sizeof(*p), GFP_KERNEL);	if (!p)		return NULL;	p->curr_hash = pos2maj_hash(filp, pos);	p->curr_minor_hash = pos2min_hash(filp, pos);	return p;} void ext4_htree_free_dir_info(struct dir_private_info *p){	free_rb_tree_fname(&p->root);	kfree(p);} /* * Given a directory entry, enter it into the fname rb tree. * * When filename encryption is enabled, the dirent will hold the * encrypted filename, while the htree will hold decrypted filename. * The decrypted filename is passed in via ent_name.  parameter. */int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,			     __u32 minor_hash,			    struct ext4_dir_entry_2 *dirent,			    struct fscrypt_str *ent_name){	struct rb_node **p, *parent = NULL;	struct fname *fname, *new_fn;	struct dir_private_info *info;	int len; 	info = dir_file->private_data;	p = &info->root.rb_node; 	/* Create and allocate the fname structure */	len = sizeof(struct fname) + ent_name->len + 1;	new_fn = kzalloc(len, GFP_KERNEL);	if (!new_fn)		return -ENOMEM;	new_fn->hash = hash;	new_fn->minor_hash = minor_hash;	new_fn->inode = le32_to_cpu(dirent->inode);	new_fn->name_len = ent_name->len;	new_fn->file_type = dirent->file_type;	memcpy(new_fn->name, ent_name->name, ent_name->len); 	while (*p) {		parent = *p;		fname = rb_entry(parent, struct fname, rb_hash); 		/*		 * If the hash and minor hash match up, then we put		 * them on a linked list.  This rarely happens...		 */		if ((new_fn->hash == fname->hash) &&		    (new_fn->minor_hash == fname->minor_hash)) {			new_fn->next = fname->next;			fname->next = new_fn;			return 0;		} 		if (new_fn->hash < fname->hash)			p = &(*p)->rb_left;		else if (new_fn->hash > fname->hash)			p = &(*p)->rb_right;		else if (new_fn->minor_hash < fname->minor_hash)			p = &(*p)->rb_left;		else /* if (new_fn->minor_hash > fname->minor_hash) */			p = &(*p)->rb_right;	} 	rb_link_node(&new_fn->rb_hash, parent, p);	rb_insert_color(&new_fn->rb_hash, &info->root);	return 0;}   /*

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