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Back in the old days, the "ascii-ci" feature was created to implement case-insensitive directory entry lookups for latin1-encoded names and remove the large overhead of Samba's case-insensitive lookup code. UTF8 names were not allowed, but nobody explicitly wrote in the documentation that this was only expected to work if the system used latin1 names. The kernel tolower function was selected to prepare names for hashed lookups. There's a major discrepancy in the function that computes directory entry hashes for filesystems that have ASCII case-insensitive lookups enabled. The root of this is that the kernel and glibc's tolower implementations have differing behavior for extended ASCII accented characters. I wrote a program to spit out characters for which the tolower() return value is different from the input: glibc tolower: 65:A 66:B 67:C 68:D 69:E 70:F 71:G 72:H 73:I 74:J 75:K 76:L 77:M 78:N 79:O 80:P 81:Q 82:R 83:S 84:T 85:U 86:V 87:W 88:X 89:Y 90:Z kernel tolower: 65:A 66:B 67:C 68:D 69:E 70:F 71:G 72:H 73:I 74:J 75:K 76:L 77:M 78:N 79:O 80:P 81:Q 82:R 83:S 84:T 85:U 86:V 87:W 88:X 89:Y 90:Z 192:À 193:Á 194:Â 195:Ã 196:Ä 197:Å 198:Æ 199:Ç 200:È 201:É 202:Ê 203:Ë 204:Ì 205:Í 206:Î 207:Ï 208:Ð 209:Ñ 210:Ò 211:Ó 212:Ô 213:Õ 214:Ö 215:× 216:Ø 217:Ù 218:Ú 219:Û 220:Ü 221:Ý 222:Þ Which means that the kernel and userspace do not agree on the hash value for a directory filename that contains those higher values. The hash values are written into the leaf index block of directories that are larger than two blocks in size, which means that xfs_repair will flag these directories as having corrupted hash indexes and rewrite the index with hash values that the kernel now will not recognize. Because the ascii-ci feature is not frequently enabled and the kernel touches filesystems far more frequently than xfs_repair does, fix this by encoding the kernel's toupper predicate and tolower functions into libxfs. Give the new functions less provocative names to make it really obvious that this is a pre-hash name preparation function, and nothing else. This change makes userspace's behavior consistent with the kernel. Found by auditing obfuscate_name in xfs_metadump as part of working on parent pointers, wondering how it could possibly work correctly with ci filesystems, writing a test tool to create a directory with hash-colliding names, and watching xfs_repair flag it. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
283 lines
8.5 KiB
C
283 lines
8.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (c) 2000-2001,2005 Silicon Graphics, Inc.
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* All Rights Reserved.
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*/
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#ifndef __XFS_DIR2_H__
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#define __XFS_DIR2_H__
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#include "xfs_da_format.h"
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#include "xfs_da_btree.h"
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struct xfs_da_args;
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struct xfs_inode;
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struct xfs_mount;
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struct xfs_trans;
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struct xfs_dir2_sf_hdr;
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struct xfs_dir2_sf_entry;
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struct xfs_dir2_data_hdr;
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struct xfs_dir2_data_entry;
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struct xfs_dir2_data_unused;
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struct xfs_dir3_icfree_hdr;
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struct xfs_dir3_icleaf_hdr;
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extern const struct xfs_name xfs_name_dotdot;
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/*
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* Convert inode mode to directory entry filetype
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*/
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extern unsigned char xfs_mode_to_ftype(int mode);
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/*
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* Generic directory interface routines
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*/
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extern void xfs_dir_startup(void);
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extern int xfs_da_mount(struct xfs_mount *mp);
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extern void xfs_da_unmount(struct xfs_mount *mp);
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extern int xfs_dir_isempty(struct xfs_inode *dp);
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extern int xfs_dir_init(struct xfs_trans *tp, struct xfs_inode *dp,
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struct xfs_inode *pdp);
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extern int xfs_dir_createname(struct xfs_trans *tp, struct xfs_inode *dp,
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const struct xfs_name *name, xfs_ino_t inum,
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xfs_extlen_t tot);
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extern int xfs_dir_lookup(struct xfs_trans *tp, struct xfs_inode *dp,
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const struct xfs_name *name, xfs_ino_t *inum,
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struct xfs_name *ci_name);
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extern int xfs_dir_removename(struct xfs_trans *tp, struct xfs_inode *dp,
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struct xfs_name *name, xfs_ino_t ino,
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xfs_extlen_t tot);
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extern int xfs_dir_replace(struct xfs_trans *tp, struct xfs_inode *dp,
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const struct xfs_name *name, xfs_ino_t inum,
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xfs_extlen_t tot);
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extern int xfs_dir_canenter(struct xfs_trans *tp, struct xfs_inode *dp,
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struct xfs_name *name);
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/*
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* Direct call from the bmap code, bypassing the generic directory layer.
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*/
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extern int xfs_dir2_sf_to_block(struct xfs_da_args *args);
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/*
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* Interface routines used by userspace utilities
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*/
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extern int xfs_dir2_isblock(struct xfs_da_args *args, bool *isblock);
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extern int xfs_dir2_isleaf(struct xfs_da_args *args, bool *isleaf);
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extern int xfs_dir2_shrink_inode(struct xfs_da_args *args, xfs_dir2_db_t db,
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struct xfs_buf *bp);
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extern void xfs_dir2_data_freescan(struct xfs_mount *mp,
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struct xfs_dir2_data_hdr *hdr, int *loghead);
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extern void xfs_dir2_data_log_entry(struct xfs_da_args *args,
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struct xfs_buf *bp, struct xfs_dir2_data_entry *dep);
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extern void xfs_dir2_data_log_header(struct xfs_da_args *args,
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struct xfs_buf *bp);
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extern void xfs_dir2_data_log_unused(struct xfs_da_args *args,
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struct xfs_buf *bp, struct xfs_dir2_data_unused *dup);
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extern void xfs_dir2_data_make_free(struct xfs_da_args *args,
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struct xfs_buf *bp, xfs_dir2_data_aoff_t offset,
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xfs_dir2_data_aoff_t len, int *needlogp, int *needscanp);
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extern int xfs_dir2_data_use_free(struct xfs_da_args *args,
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struct xfs_buf *bp, struct xfs_dir2_data_unused *dup,
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xfs_dir2_data_aoff_t offset, xfs_dir2_data_aoff_t len,
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int *needlogp, int *needscanp);
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extern struct xfs_dir2_data_free *xfs_dir2_data_freefind(
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struct xfs_dir2_data_hdr *hdr, struct xfs_dir2_data_free *bf,
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struct xfs_dir2_data_unused *dup);
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extern int xfs_dir_ino_validate(struct xfs_mount *mp, xfs_ino_t ino);
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extern const struct xfs_buf_ops xfs_dir3_block_buf_ops;
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extern const struct xfs_buf_ops xfs_dir3_leafn_buf_ops;
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extern const struct xfs_buf_ops xfs_dir3_leaf1_buf_ops;
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extern const struct xfs_buf_ops xfs_dir3_free_buf_ops;
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extern const struct xfs_buf_ops xfs_dir3_data_buf_ops;
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/*
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* Directory offset/block conversion functions.
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*
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* DB blocks here are logical directory block numbers, not filesystem blocks.
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*/
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/*
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* Convert dataptr to byte in file space
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*/
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static inline xfs_dir2_off_t
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xfs_dir2_dataptr_to_byte(xfs_dir2_dataptr_t dp)
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{
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return (xfs_dir2_off_t)dp << XFS_DIR2_DATA_ALIGN_LOG;
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}
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/*
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* Convert byte in file space to dataptr. It had better be aligned.
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*/
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static inline xfs_dir2_dataptr_t
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xfs_dir2_byte_to_dataptr(xfs_dir2_off_t by)
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{
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return (xfs_dir2_dataptr_t)(by >> XFS_DIR2_DATA_ALIGN_LOG);
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}
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/*
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* Convert byte in space to (DB) block
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*/
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static inline xfs_dir2_db_t
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xfs_dir2_byte_to_db(struct xfs_da_geometry *geo, xfs_dir2_off_t by)
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{
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return (xfs_dir2_db_t)(by >> geo->blklog);
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}
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/*
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* Convert dataptr to a block number
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*/
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static inline xfs_dir2_db_t
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xfs_dir2_dataptr_to_db(struct xfs_da_geometry *geo, xfs_dir2_dataptr_t dp)
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{
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return xfs_dir2_byte_to_db(geo, xfs_dir2_dataptr_to_byte(dp));
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}
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/*
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* Convert byte in space to offset in a block
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*/
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static inline xfs_dir2_data_aoff_t
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xfs_dir2_byte_to_off(struct xfs_da_geometry *geo, xfs_dir2_off_t by)
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{
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return (xfs_dir2_data_aoff_t)(by & (geo->blksize - 1));
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}
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/*
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* Convert dataptr to a byte offset in a block
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*/
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static inline xfs_dir2_data_aoff_t
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xfs_dir2_dataptr_to_off(struct xfs_da_geometry *geo, xfs_dir2_dataptr_t dp)
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{
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return xfs_dir2_byte_to_off(geo, xfs_dir2_dataptr_to_byte(dp));
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}
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/*
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* Convert block and offset to byte in space
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*/
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static inline xfs_dir2_off_t
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xfs_dir2_db_off_to_byte(struct xfs_da_geometry *geo, xfs_dir2_db_t db,
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xfs_dir2_data_aoff_t o)
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{
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return ((xfs_dir2_off_t)db << geo->blklog) + o;
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}
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/*
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* Convert block (DB) to block (dablk)
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*/
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static inline xfs_dablk_t
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xfs_dir2_db_to_da(struct xfs_da_geometry *geo, xfs_dir2_db_t db)
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{
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return (xfs_dablk_t)(db << (geo->blklog - geo->fsblog));
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}
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/*
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* Convert byte in space to (DA) block
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*/
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static inline xfs_dablk_t
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xfs_dir2_byte_to_da(struct xfs_da_geometry *geo, xfs_dir2_off_t by)
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{
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return xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, by));
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}
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/*
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* Convert block and offset to dataptr
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*/
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static inline xfs_dir2_dataptr_t
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xfs_dir2_db_off_to_dataptr(struct xfs_da_geometry *geo, xfs_dir2_db_t db,
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xfs_dir2_data_aoff_t o)
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{
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return xfs_dir2_byte_to_dataptr(xfs_dir2_db_off_to_byte(geo, db, o));
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}
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/*
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* Convert block (dablk) to block (DB)
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*/
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static inline xfs_dir2_db_t
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xfs_dir2_da_to_db(struct xfs_da_geometry *geo, xfs_dablk_t da)
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{
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return (xfs_dir2_db_t)(da >> (geo->blklog - geo->fsblog));
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}
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/*
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* Convert block (dablk) to byte offset in space
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*/
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static inline xfs_dir2_off_t
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xfs_dir2_da_to_byte(struct xfs_da_geometry *geo, xfs_dablk_t da)
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{
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return xfs_dir2_db_off_to_byte(geo, xfs_dir2_da_to_db(geo, da), 0);
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}
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/*
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* Directory tail pointer accessor functions. Based on block geometry.
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*/
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static inline struct xfs_dir2_block_tail *
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xfs_dir2_block_tail_p(struct xfs_da_geometry *geo, struct xfs_dir2_data_hdr *hdr)
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{
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return ((struct xfs_dir2_block_tail *)
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((char *)hdr + geo->blksize)) - 1;
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}
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static inline struct xfs_dir2_leaf_tail *
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xfs_dir2_leaf_tail_p(struct xfs_da_geometry *geo, struct xfs_dir2_leaf *lp)
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{
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return (struct xfs_dir2_leaf_tail *)
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((char *)lp + geo->blksize -
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sizeof(struct xfs_dir2_leaf_tail));
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}
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/*
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* The Linux API doesn't pass down the total size of the buffer
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* we read into down to the filesystem. With the filldir concept
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* it's not needed for correct information, but the XFS dir2 leaf
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* code wants an estimate of the buffer size to calculate it's
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* readahead window and size the buffers used for mapping to
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* physical blocks.
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*
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* Try to give it an estimate that's good enough, maybe at some
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* point we can change the ->readdir prototype to include the
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* buffer size. For now we use the current glibc buffer size.
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* musl libc hardcodes 2k and dietlibc uses PAGE_SIZE.
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*/
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#define XFS_READDIR_BUFSIZE (32768)
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unsigned char xfs_dir3_get_dtype(struct xfs_mount *mp, uint8_t filetype);
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unsigned int xfs_dir3_data_end_offset(struct xfs_da_geometry *geo,
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struct xfs_dir2_data_hdr *hdr);
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bool xfs_dir2_namecheck(const void *name, size_t length);
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/*
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* The "ascii-ci" feature was created to speed up case-insensitive lookups for
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* a Samba product. Because of the inherent problems with CI and UTF-8
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* encoding, etc, it was decided that Samba would be configured to export
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* latin1/iso 8859-1 encodings as that covered >90% of the target markets for
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* the product. Hence the "ascii-ci" casefolding code could be encoded into
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* the XFS directory operations and remove all the overhead of casefolding from
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* Samba.
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*
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* To provide consistent hashing behavior between the userspace and kernel,
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* these functions prepare names for hashing by transforming specific bytes
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* to other bytes. Robustness with other encodings is not guaranteed.
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*/
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static inline bool xfs_ascii_ci_need_xfrm(unsigned char c)
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{
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if (c >= 0x41 && c <= 0x5a) /* A-Z */
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return true;
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if (c >= 0xc0 && c <= 0xd6) /* latin A-O with accents */
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return true;
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if (c >= 0xd8 && c <= 0xde) /* latin O-Y with accents */
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return true;
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return false;
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}
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static inline unsigned char xfs_ascii_ci_xfrm(unsigned char c)
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{
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if (xfs_ascii_ci_need_xfrm(c))
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c -= 'A' - 'a';
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return c;
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}
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#endif /* __XFS_DIR2_H__ */
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