freebsd-dev/sbin/fsck_ffs/fsck.h
Kirk McKusick 0061238fb0 This update eliminates a kernel stack disclosure bug in UFS/FFS
directory entries that is caused by uninitialized directory entry
padding written to the disk. It can be viewed by any user with read
access to that directory. Up to 3 bytes of kernel stack are disclosed
per file entry, depending on the the amount of padding the kernel
needs to pad out the entry to a 32 bit boundry. The offset in the
kernel stack that is disclosed is a function of the filename size.
Furthermore, if the user can create files in a directory, this 3
byte window can be expanded 3 bytes at a time to a 254 byte window
with 75% of the data in that window exposed. The additional exposure
is done by removing the entry, creating a new entry with a 4-byte
longer name, extracting 3 more bytes by reading the directory, and
repeating until a 252 byte name is created.

This exploit works in part because the area of the kernel stack
that is being disclosed is in an area that typically doesn't change
that often (perhaps a few times a second on a lightly loaded system),
and these file creates and unlinks themselves don't overwrite the
area of kernel stack being disclosed.

It appears that this bug originated with the creation of the Fast
File System in 4.1b-BSD (Circa 1982, more than 36 years ago!), and
is likely present in every Unix or Unix-like system that uses
UFS/FFS. Amazingly, nobody noticed until now.

This update also adds the -z flag to fsck_ffs to have it scrub
the leaked information in the name padding of existing directories.
It only needs to be run once on each UFS/FFS filesystem after a
patched kernel is installed and running.

Submitted by: David G. Lawrence <dg@dglawrence.com>
Reviewed by:  kib
MFC after:    1 week
2019-05-03 21:54:14 +00:00

486 lines
18 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause and BSD-2-Clause-FreeBSD
*
* Copyright (c) 2002 Networks Associates Technology, Inc.
* All rights reserved.
*
* This software was developed for the FreeBSD Project by Marshall
* Kirk McKusick and Network Associates Laboratories, the Security
* Research Division of Network Associates, Inc. under DARPA/SPAWAR
* contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS
* research program.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* Copyright (c) 1980, 1986, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)fsck.h 8.4 (Berkeley) 5/9/95
* $FreeBSD$
*/
#ifndef _FSCK_H_
#define _FSCK_H_
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/queue.h>
#define MAXDUP 10 /* limit on dup blks (per inode) */
#define MAXBAD 10 /* limit on bad blks (per inode) */
#define MINBUFS 10 /* minimum number of buffers required */
#define MAXBUFS 40 /* maximum space to allocate to buffers */
#define INOBUFSIZE 64*1024 /* size of buffer to read inodes in pass1 */
#define ZEROBUFSIZE (dev_bsize * 128) /* size of zero buffer used by -Z */
union dinode {
struct ufs1_dinode dp1;
struct ufs2_dinode dp2;
};
#define DIP(dp, field) \
((sblock.fs_magic == FS_UFS1_MAGIC) ? \
(dp)->dp1.field : (dp)->dp2.field)
#define DIP_SET(dp, field, val) do { \
if (sblock.fs_magic == FS_UFS1_MAGIC) \
(dp)->dp1.field = (val); \
else \
(dp)->dp2.field = (val); \
} while (0)
/*
* Each inode on the file system is described by the following structure.
* The linkcnt is initially set to the value in the inode. Each time it
* is found during the descent in passes 2, 3, and 4 the count is
* decremented. Any inodes whose count is non-zero after pass 4 needs to
* have its link count adjusted by the value remaining in ino_linkcnt.
*/
struct inostat {
char ino_state; /* state of inode, see below */
char ino_type; /* type of inode */
short ino_linkcnt; /* number of links not found */
};
/*
* Inode states.
*/
#define USTATE 0x1 /* inode not allocated */
#define FSTATE 0x2 /* inode is file */
#define FZLINK 0x3 /* inode is file with a link count of zero */
#define DSTATE 0x4 /* inode is directory */
#define DZLINK 0x5 /* inode is directory with a zero link count */
#define DFOUND 0x6 /* directory found during descent */
/* 0x7 UNUSED - see S_IS_DVALID() definition */
#define DCLEAR 0x8 /* directory is to be cleared */
#define FCLEAR 0x9 /* file is to be cleared */
/* DUNFOUND === (state == DSTATE || state == DZLINK) */
#define S_IS_DUNFOUND(state) (((state) & ~0x1) == DSTATE)
/* DVALID === (state == DSTATE || state == DZLINK || state == DFOUND) */
#define S_IS_DVALID(state) (((state) & ~0x3) == DSTATE)
#define INO_IS_DUNFOUND(ino) S_IS_DUNFOUND(inoinfo(ino)->ino_state)
#define INO_IS_DVALID(ino) S_IS_DVALID(inoinfo(ino)->ino_state)
/*
* Inode state information is contained on per cylinder group lists
* which are described by the following structure.
*/
struct inostatlist {
long il_numalloced; /* number of inodes allocated in this cg */
struct inostat *il_stat;/* inostat info for this cylinder group */
} *inostathead;
/*
* buffer cache structure.
*/
struct bufarea {
TAILQ_ENTRY(bufarea) b_list; /* buffer list */
ufs2_daddr_t b_bno;
int b_size;
int b_errs;
int b_flags;
int b_type;
union {
char *b_buf; /* buffer space */
ufs1_daddr_t *b_indir1; /* UFS1 indirect block */
ufs2_daddr_t *b_indir2; /* UFS2 indirect block */
struct fs *b_fs; /* super block */
struct cg *b_cg; /* cylinder group */
struct ufs1_dinode *b_dinode1; /* UFS1 inode block */
struct ufs2_dinode *b_dinode2; /* UFS2 inode block */
} b_un;
char b_dirty;
};
#define IBLK(bp, i) \
((sblock.fs_magic == FS_UFS1_MAGIC) ? \
(bp)->b_un.b_indir1[i] : (bp)->b_un.b_indir2[i])
#define IBLK_SET(bp, i, val) do { \
if (sblock.fs_magic == FS_UFS1_MAGIC) \
(bp)->b_un.b_indir1[i] = (val); \
else \
(bp)->b_un.b_indir2[i] = (val); \
} while (0)
/*
* Buffer flags
*/
#define B_INUSE 0x00000001 /* Buffer is in use */
/*
* Type of data in buffer
*/
#define BT_UNKNOWN 0 /* Buffer holds a superblock */
#define BT_SUPERBLK 1 /* Buffer holds a superblock */
#define BT_CYLGRP 2 /* Buffer holds a cylinder group map */
#define BT_LEVEL1 3 /* Buffer holds single level indirect */
#define BT_LEVEL2 4 /* Buffer holds double level indirect */
#define BT_LEVEL3 5 /* Buffer holds triple level indirect */
#define BT_EXTATTR 6 /* Buffer holds external attribute data */
#define BT_INODES 7 /* Buffer holds external attribute data */
#define BT_DIRDATA 8 /* Buffer holds directory data */
#define BT_DATA 9 /* Buffer holds user data */
#define BT_NUMBUFTYPES 10
#define BT_NAMES { \
"unknown", \
"Superblock", \
"Cylinder Group", \
"Single Level Indirect", \
"Double Level Indirect", \
"Triple Level Indirect", \
"External Attribute", \
"Inode Block", \
"Directory Contents", \
"User Data" }
extern long readcnt[BT_NUMBUFTYPES];
extern long totalreadcnt[BT_NUMBUFTYPES];
extern struct timespec readtime[BT_NUMBUFTYPES];
extern struct timespec totalreadtime[BT_NUMBUFTYPES];
extern struct timespec startprog;
extern struct bufarea sblk; /* file system superblock */
extern struct bufarea *pdirbp; /* current directory contents */
extern struct bufarea *pbp; /* current inode block */
#define dirty(bp) do { \
if (fswritefd < 0) \
pfatal("SETTING DIRTY FLAG IN READ_ONLY MODE\n"); \
else \
(bp)->b_dirty = 1; \
} while (0)
#define initbarea(bp, type) do { \
(bp)->b_dirty = 0; \
(bp)->b_bno = (ufs2_daddr_t)-1; \
(bp)->b_flags = 0; \
(bp)->b_type = type; \
} while (0)
#define sbdirty() dirty(&sblk)
#define sblock (*sblk.b_un.b_fs)
enum fixstate {DONTKNOW, NOFIX, FIX, IGNORE};
extern ino_t cursnapshot;
struct inodesc {
enum fixstate id_fix; /* policy on fixing errors */
int (*id_func)(struct inodesc *);
/* function to be applied to blocks of inode */
ino_t id_number; /* inode number described */
ino_t id_parent; /* for DATA nodes, their parent */
ufs_lbn_t id_lbn; /* logical block number of current block */
ufs2_daddr_t id_blkno; /* current block number being examined */
int id_level; /* level of indirection of this block */
int id_numfrags; /* number of frags contained in block */
ufs_lbn_t id_lballoc; /* pass1: last LBN that is allocated */
off_t id_filesize; /* for DATA nodes, the size of the directory */
ufs2_daddr_t id_entryno;/* for DATA nodes, current entry number */
int id_loc; /* for DATA nodes, current location in dir */
struct direct *id_dirp; /* for DATA nodes, ptr to current entry */
char *id_name; /* for DATA nodes, name to find or enter */
char id_type; /* type of descriptor, DATA or ADDR */
};
/* file types */
#define DATA 1 /* a directory */
#define SNAP 2 /* a snapshot */
#define ADDR 3 /* anything but a directory or a snapshot */
/*
* Linked list of duplicate blocks.
*
* The list is composed of two parts. The first part of the
* list (from duplist through the node pointed to by muldup)
* contains a single copy of each duplicate block that has been
* found. The second part of the list (from muldup to the end)
* contains duplicate blocks that have been found more than once.
* To check if a block has been found as a duplicate it is only
* necessary to search from duplist through muldup. To find the
* total number of times that a block has been found as a duplicate
* the entire list must be searched for occurrences of the block
* in question. The following diagram shows a sample list where
* w (found twice), x (found once), y (found three times), and z
* (found once) are duplicate block numbers:
*
* w -> y -> x -> z -> y -> w -> y
* ^ ^
* | |
* duplist muldup
*/
struct dups {
struct dups *next;
ufs2_daddr_t dup;
};
struct dups *duplist; /* head of dup list */
struct dups *muldup; /* end of unique duplicate dup block numbers */
/*
* Inode cache data structures.
*/
struct inoinfo {
struct inoinfo *i_nexthash; /* next entry in hash chain */
ino_t i_number; /* inode number of this entry */
ino_t i_parent; /* inode number of parent */
ino_t i_dotdot; /* inode number of `..' */
size_t i_isize; /* size of inode */
u_int i_numblks; /* size of block array in bytes */
ufs2_daddr_t i_blks[1]; /* actually longer */
} **inphead, **inpsort;
extern long dirhash, inplast;
extern unsigned long numdirs, listmax;
extern long countdirs; /* number of directories we actually found */
#define MIBSIZE 3 /* size of fsck sysctl MIBs */
extern int adjrefcnt[MIBSIZE]; /* MIB command to adjust inode reference cnt */
extern int adjblkcnt[MIBSIZE]; /* MIB command to adjust inode block count */
extern int setsize[MIBSIZE]; /* MIB command to set inode size */
extern int adjndir[MIBSIZE]; /* MIB command to adjust number of directories */
extern int adjnbfree[MIBSIZE]; /* MIB command to adjust number of free blocks */
extern int adjnifree[MIBSIZE]; /* MIB command to adjust number of free inodes */
extern int adjnffree[MIBSIZE]; /* MIB command to adjust number of free frags */
extern int adjnumclusters[MIBSIZE]; /* MIB command to adjust number of free clusters */
extern int freefiles[MIBSIZE]; /* MIB command to free a set of files */
extern int freedirs[MIBSIZE]; /* MIB command to free a set of directories */
extern int freeblks[MIBSIZE]; /* MIB command to free a set of data blocks */
extern struct fsck_cmd cmd; /* sysctl file system update commands */
extern char snapname[BUFSIZ]; /* when doing snapshots, the name of the file */
extern char *cdevname; /* name of device being checked */
extern long dev_bsize; /* computed value of DEV_BSIZE */
extern long secsize; /* actual disk sector size */
extern u_int real_dev_bsize; /* actual disk sector size, not overridden */
extern char nflag; /* assume a no response */
extern char yflag; /* assume a yes response */
extern int bkgrdflag; /* use a snapshot to run on an active system */
extern off_t bflag; /* location of alternate super block */
extern int debug; /* output debugging info */
extern int Eflag; /* delete empty data blocks */
extern int Zflag; /* zero empty data blocks */
extern int zflag; /* zero unused directory space */
extern int inoopt; /* trim out unused inodes */
extern char ckclean; /* only do work if not cleanly unmounted */
extern int cvtlevel; /* convert to newer file system format */
extern int ckhashadd; /* check hashes to be added */
extern int bkgrdcheck; /* determine if background check is possible */
extern int bkgrdsumadj; /* whether the kernel have ability to adjust superblock summary */
extern char usedsoftdep; /* just fix soft dependency inconsistencies */
extern char preen; /* just fix normal inconsistencies */
extern char rerun; /* rerun fsck. Only used in non-preen mode */
extern int returntosingle; /* 1 => return to single user mode on exit */
extern char resolved; /* cleared if unresolved changes => not clean */
extern char havesb; /* superblock has been read */
extern char skipclean; /* skip clean file systems if preening */
extern int fsmodified; /* 1 => write done to file system */
extern int fsreadfd; /* file descriptor for reading file system */
extern int fswritefd; /* file descriptor for writing file system */
extern struct uufsd disk; /* libufs user-ufs disk structure */
extern int surrender; /* Give up if reads fail */
extern int wantrestart; /* Restart fsck on early termination */
extern ufs2_daddr_t maxfsblock; /* number of blocks in the file system */
extern char *blockmap; /* ptr to primary blk allocation map */
extern ino_t maxino; /* number of inodes in file system */
extern ino_t lfdir; /* lost & found directory inode number */
extern const char *lfname; /* lost & found directory name */
extern int lfmode; /* lost & found directory creation mode */
extern ufs2_daddr_t n_blks; /* number of blocks in use */
extern ino_t n_files; /* number of files in use */
extern volatile sig_atomic_t got_siginfo; /* received a SIGINFO */
extern volatile sig_atomic_t got_sigalarm; /* received a SIGALRM */
#define clearinode(dp) \
if (sblock.fs_magic == FS_UFS1_MAGIC) { \
(dp)->dp1 = ufs1_zino; \
} else { \
(dp)->dp2 = ufs2_zino; \
}
extern struct ufs1_dinode ufs1_zino;
extern struct ufs2_dinode ufs2_zino;
#define setbmap(blkno) setbit(blockmap, blkno)
#define testbmap(blkno) isset(blockmap, blkno)
#define clrbmap(blkno) clrbit(blockmap, blkno)
#define STOP 0x01
#define SKIP 0x02
#define KEEPON 0x04
#define ALTERED 0x08
#define FOUND 0x10
#define EEXIT 8 /* Standard error exit. */
#define ERERUN 16 /* fsck needs to be re-run. */
#define ERESTART -1
int flushentry(void);
/*
* Wrapper for malloc() that flushes the cylinder group cache to try
* to get space.
*/
static inline void*
Malloc(size_t size)
{
void *retval;
while ((retval = malloc(size)) == NULL)
if (flushentry() == 0)
break;
return (retval);
}
/*
* Wrapper for calloc() that flushes the cylinder group cache to try
* to get space.
*/
static inline void*
Calloc(size_t cnt, size_t size)
{
void *retval;
while ((retval = calloc(cnt, size)) == NULL)
if (flushentry() == 0)
break;
return (retval);
}
struct fstab;
void adjust(struct inodesc *, int lcnt);
ufs2_daddr_t allocblk(long frags);
ino_t allocdir(ino_t parent, ino_t request, int mode);
ino_t allocino(ino_t request, int type);
void blkerror(ino_t ino, const char *type, ufs2_daddr_t blk);
char *blockcheck(char *name);
int blread(int fd, char *buf, ufs2_daddr_t blk, long size);
void bufinit(void);
void blwrite(int fd, char *buf, ufs2_daddr_t blk, ssize_t size);
void blerase(int fd, ufs2_daddr_t blk, long size);
void blzero(int fd, ufs2_daddr_t blk, long size);
void cacheino(union dinode *dp, ino_t inumber);
void catch(int);
void catchquit(int);
void cgdirty(struct bufarea *);
int changeino(ino_t dir, const char *name, ino_t newnum);
int check_cgmagic(int cg, struct bufarea *cgbp);
int chkrange(ufs2_daddr_t blk, int cnt);
void ckfini(int markclean);
int ckinode(union dinode *dp, struct inodesc *);
void clri(struct inodesc *, const char *type, int flag);
int clearentry(struct inodesc *);
void direrror(ino_t ino, const char *errmesg);
int dirscan(struct inodesc *);
int dofix(struct inodesc *, const char *msg);
int eascan(struct inodesc *, struct ufs2_dinode *dp);
void fileerror(ino_t cwd, ino_t ino, const char *errmesg);
void finalIOstats(void);
int findino(struct inodesc *);
int findname(struct inodesc *);
void flush(int fd, struct bufarea *bp);
void freeblk(ufs2_daddr_t blkno, long frags);
void freeino(ino_t ino);
void freeinodebuf(void);
void fsutilinit(void);
int ftypeok(union dinode *dp);
void getblk(struct bufarea *bp, ufs2_daddr_t blk, long size);
struct bufarea *cglookup(int cg);
struct bufarea *getdatablk(ufs2_daddr_t blkno, long size, int type);
struct inoinfo *getinoinfo(ino_t inumber);
union dinode *getnextinode(ino_t inumber, int rebuildcg);
void getpathname(char *namebuf, ino_t curdir, ino_t ino);
union dinode *ginode(ino_t inumber);
void infohandler(int sig);
void alarmhandler(int sig);
void inocleanup(void);
void inodirty(union dinode *);
struct inostat *inoinfo(ino_t inum);
void IOstats(char *what);
int linkup(ino_t orphan, ino_t parentdir, char *name);
int makeentry(ino_t parent, ino_t ino, const char *name);
void panic(const char *fmt, ...) __printflike(1, 2);
void pass1(void);
void pass1b(void);
int pass1check(struct inodesc *);
void pass2(void);
void pass3(void);
void pass4(void);
int pass4check(struct inodesc *);
void pass5(void);
void pfatal(const char *fmt, ...) __printflike(1, 2);
void propagate(void);
void prtinode(ino_t ino, union dinode *dp);
void pwarn(const char *fmt, ...) __printflike(1, 2);
int readsb(int listerr);
int reply(const char *question);
void rwerror(const char *mesg, ufs2_daddr_t blk);
void sblock_init(void);
void setinodebuf(ino_t);
int setup(char *dev);
void gjournal_check(const char *filesys);
int suj_check(const char *filesys);
void update_maps(struct cg *, struct cg*, int);
void fsckinit(void);
#endif /* !_FSCK_H_ */