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freebsd-skq/sys/gnu/fs/ext2fs/ext2_lookup.c
Robert Watson 9ca435893b In order to better support flexible and extensible access control, 
make a series of modifications to the credential arguments relating
to file read and write operations to cliarfy which credential is
used for what:

- Change fo_read() and fo_write() to accept "active_cred" instead of
  "cred", and change the semantics of consumers of fo_read() and
  fo_write() to pass the active credential of the thread requesting
  an operation rather than the cached file cred.  The cached file
  cred is still available in fo_read() and fo_write() consumers
  via fp->f_cred.  These changes largely in sys_generic.c.

For each implementation of fo_read() and fo_write(), update cred
usage to reflect this change and maintain current semantics:

- badfo_readwrite() unchanged
- kqueue_read/write() unchanged
  pipe_read/write() now authorize MAC using active_cred rather
  than td->td_ucred
- soo_read/write() unchanged
- vn_read/write() now authorize MAC using active_cred but
  VOP_READ/WRITE() with fp->f_cred

Modify vn_rdwr() to accept two credential arguments instead of a
single credential: active_cred and file_cred.  Use active_cred
for MAC authorization, and select a credential for use in
VOP_READ/WRITE() based on whether file_cred is NULL or not.  If
file_cred is provided, authorize the VOP using that cred,
otherwise the active credential, matching current semantics.

Modify current vn_rdwr() consumers to pass a file_cred if used
in the context of a struct file, and to always pass active_cred.
When vn_rdwr() is used without a file_cred, pass NOCRED.

These changes should maintain current semantics for read/write,
but avoid a redundant passing of fp->f_cred, as well as making
it more clear what the origin of each credential is in file
descriptor read/write operations.

Follow-up commits will make similar changes to other file descriptor
operations, and modify the MAC framework to pass both credentials
to MAC policy modules so they can implement either semantic for
revocation.

Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, NAI Labs
2002-08-15 20:55:08 +00:00

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/*
* modified for Lites 1.1
*
* Aug 1995, Godmar Back (gback@cs.utah.edu)
* University of Utah, Department of Computer Science
*/
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*
* @(#)ufs_lookup.c 8.6 (Berkeley) 4/1/94
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/namei.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/malloc.h>
#include <sys/dirent.h>
#include <sys/sysctl.h>
#include <ufs/ufs/dir.h>
#include <gnu/ext2fs/inode.h>
#include <gnu/ext2fs/ext2_mount.h>
#include <gnu/ext2fs/ext2_extern.h>
#include <gnu/ext2fs/ext2_fs.h>
#include <gnu/ext2fs/ext2_fs_sb.h>
#ifdef DIAGNOSTIC
static int dirchk = 1;
#else
static int dirchk = 0;
#endif
SYSCTL_NODE(_vfs, OID_AUTO, e2fs, CTLFLAG_RD, 0, "EXT2FS filesystem");
SYSCTL_INT(_vfs_e2fs, OID_AUTO, dircheck, CTLFLAG_RW, &dirchk, 0, "");
/*
DIRBLKSIZE in ffs is DEV_BSIZE (in most cases 512)
while it is the native blocksize in ext2fs - thus, a #define
is no longer appropriate
*/
#undef DIRBLKSIZ
static u_char ext2_ft_to_dt[] = {
DT_UNKNOWN, /* EXT2_FT_UNKNOWN */
DT_REG, /* EXT2_FT_REG_FILE */
DT_DIR, /* EXT2_FT_DIR */
DT_CHR, /* EXT2_FT_CHRDEV */
DT_BLK, /* EXT2_FT_BLKDEV */
DT_FIFO, /* EXT2_FT_FIFO */
DT_SOCK, /* EXT2_FT_SOCK */
DT_LNK, /* EXT2_FT_SYMLINK */
};
#define FTTODT(ft) \
((ft) > sizeof(ext2_ft_to_dt) / sizeof(ext2_ft_to_dt[0]) ? \
DT_UNKNOWN : ext2_ft_to_dt[(ft)])
static u_char dt_to_ext2_ft[] = {
EXT2_FT_UNKNOWN, /* DT_UNKNOWN */
EXT2_FT_FIFO, /* DT_FIFO */
EXT2_FT_CHRDEV, /* DT_CHR */
EXT2_FT_UNKNOWN, /* unused */
EXT2_FT_DIR, /* DT_DIR */
EXT2_FT_UNKNOWN, /* unused */
EXT2_FT_BLKDEV, /* DT_BLK */
EXT2_FT_UNKNOWN, /* unused */
EXT2_FT_REG_FILE, /* DT_REG */
EXT2_FT_UNKNOWN, /* unused */
EXT2_FT_SYMLINK, /* DT_LNK */
EXT2_FT_UNKNOWN, /* unused */
EXT2_FT_SOCK, /* DT_SOCK */
EXT2_FT_UNKNOWN, /* unused */
EXT2_FT_UNKNOWN, /* DT_WHT */
};
#define DTTOFT(dt) \
((dt) > sizeof(dt_to_ext2_ft) / sizeof(dt_to_ext2_ft[0]) ? \
EXT2_FT_UNKNOWN : dt_to_ext2_ft[(dt)])
static int ext2_dirbadentry(struct vnode *dp, struct ext2_dir_entry_2 *de,
int entryoffsetinblock);
/*
* Vnode op for reading directories.
*
* The routine below assumes that the on-disk format of a directory
* is the same as that defined by <sys/dirent.h>. If the on-disk
* format changes, then it will be necessary to do a conversion
* from the on-disk format that read returns to the format defined
* by <sys/dirent.h>.
*/
/*
* this is exactly what we do here - the problem is that the conversion
* will blow up some entries by four bytes, so it can't be done in place.
* This is too bad. Right now the conversion is done entry by entry, the
* converted entry is sent via uiomove.
*
* XXX allocate a buffer, convert as many entries as possible, then send
* the whole buffer to uiomove
*/
int
ext2_readdir(ap)
struct vop_readdir_args /* {
struct vnode *a_vp;
struct uio *a_uio;
struct ucred *a_cred;
} */ *ap;
{
struct uio *uio = ap->a_uio;
int count, error;
struct ext2_dir_entry_2 *edp, *dp;
int ncookies;
struct dirent dstdp;
struct uio auio;
struct iovec aiov;
caddr_t dirbuf;
int DIRBLKSIZ = VTOI(ap->a_vp)->i_e2fs->s_blocksize;
int readcnt;
off_t startoffset = uio->uio_offset;
count = uio->uio_resid;
/*
* Avoid complications for partial directory entries by adjusting
* the i/o to end at a block boundary. Don't give up (like ufs
* does) if the initial adjustment gives a negative count, since
* many callers don't supply a large enough buffer. The correct
* size is a little larger than DIRBLKSIZ to allow for expansion
* of directory entries, but some callers just use 512.
*/
count -= (uio->uio_offset + count) & (DIRBLKSIZ -1);
if (count <= 0)
count += DIRBLKSIZ;
#ifdef EXT2FS_DEBUG
printf("ext2_readdir: uio_offset = %lld, uio_resid = %d, count = %d\n",
uio->uio_offset, uio->uio_resid, count);
#endif
auio = *uio;
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
auio.uio_resid = count;
auio.uio_segflg = UIO_SYSSPACE;
aiov.iov_len = count;
MALLOC(dirbuf, caddr_t, count, M_TEMP, M_WAITOK);
aiov.iov_base = dirbuf;
error = VOP_READ(ap->a_vp, &auio, 0, ap->a_cred);
if (error == 0) {
readcnt = count - auio.uio_resid;
edp = (struct ext2_dir_entry_2 *)&dirbuf[readcnt];
ncookies = 0;
bzero(&dstdp, offsetof(struct dirent, d_name));
for (dp = (struct ext2_dir_entry_2 *)dirbuf;
!error && uio->uio_resid > 0 && dp < edp; ) {
/*-
* "New" ext2fs directory entries differ in 3 ways
* from ufs on-disk ones:
* - the name is not necessarily NUL-terminated.
* - the file type field always exists and always
* follows the name length field.
* - the file type is encoded in a different way.
*
* "Old" ext2fs directory entries need no special
* conversions, since they binary compatible with
* "new" entries having a file type of 0 (i.e.,
* EXT2_FT_UNKNOWN). Splitting the old name length
* field didn't make a mess like it did in ufs,
* because ext2fs uses a machine-dependent disk
* layout.
*/
dstdp.d_fileno = dp->inode;
dstdp.d_type = FTTODT(dp->file_type);
dstdp.d_namlen = dp->name_len;
dstdp.d_reclen = GENERIC_DIRSIZ(&dstdp);
bcopy(dp->name, dstdp.d_name, dstdp.d_namlen);
bzero(dstdp.d_name + dstdp.d_namlen,
dstdp.d_reclen - offsetof(struct dirent, d_name) -
dstdp.d_namlen);
if (dp->rec_len > 0) {
if(dstdp.d_reclen <= uio->uio_resid) {
/* advance dp */
dp = (struct ext2_dir_entry_2 *)
((char *)dp + dp->rec_len);
error =
uiomove((caddr_t)&dstdp,
dstdp.d_reclen, uio);
if (!error)
ncookies++;
} else
break;
} else {
error = EIO;
break;
}
}
/* we need to correct uio_offset */
uio->uio_offset = startoffset + (caddr_t)dp - dirbuf;
if (!error && ap->a_ncookies != NULL) {
u_long *cookiep, *cookies, *ecookies;
off_t off;
if (uio->uio_segflg != UIO_SYSSPACE || uio->uio_iovcnt != 1)
panic("ext2fs_readdir: unexpected uio from NFS server");
MALLOC(cookies, u_long *, ncookies * sizeof(u_long), M_TEMP,
M_WAITOK);
off = startoffset;
for (dp = (struct ext2_dir_entry_2 *)dirbuf,
cookiep = cookies, ecookies = cookies + ncookies;
cookiep < ecookies;
dp = (struct ext2_dir_entry_2 *)((caddr_t) dp + dp->rec_len)) {
off += dp->rec_len;
*cookiep++ = (u_long) off;
}
*ap->a_ncookies = ncookies;
*ap->a_cookies = cookies;
}
}
FREE(dirbuf, M_TEMP);
if (ap->a_eofflag)
*ap->a_eofflag = VTOI(ap->a_vp)->i_size <= uio->uio_offset;
return (error);
}
/*
* Convert a component of a pathname into a pointer to a locked inode.
* This is a very central and rather complicated routine.
* If the file system is not maintained in a strict tree hierarchy,
* this can result in a deadlock situation (see comments in code below).
*
* The cnp->cn_nameiop argument is LOOKUP, CREATE, RENAME, or DELETE depending
* on whether the name is to be looked up, created, renamed, or deleted.
* When CREATE, RENAME, or DELETE is specified, information usable in
* creating, renaming, or deleting a directory entry may be calculated.
* If flag has LOCKPARENT or'ed into it and the target of the pathname
* exists, lookup returns both the target and its parent directory locked.
* When creating or renaming and LOCKPARENT is specified, the target may
* not be ".". When deleting and LOCKPARENT is specified, the target may
* be "."., but the caller must check to ensure it does an vrele and vput
* instead of two vputs.
*
* Overall outline of ufs_lookup:
*
* search for name in directory, to found or notfound
* notfound:
* if creating, return locked directory, leaving info on available slots
* else return error
* found:
* if at end of path and deleting, return information to allow delete
* if at end of path and rewriting (RENAME and LOCKPARENT), lock target
* inode and return info to allow rewrite
* if not at end, add name to cache; if at end and neither creating
* nor deleting, add name to cache
*/
int
ext2_lookup(ap)
struct vop_cachedlookup_args /* {
struct vnode *a_dvp;
struct vnode **a_vpp;
struct componentname *a_cnp;
} */ *ap;
{
struct vnode *vdp; /* vnode for directory being searched */
struct inode *dp; /* inode for directory being searched */
struct buf *bp; /* a buffer of directory entries */
struct ext2_dir_entry_2 *ep; /* the current directory entry */
int entryoffsetinblock; /* offset of ep in bp's buffer */
enum {NONE, COMPACT, FOUND} slotstatus;
doff_t slotoffset; /* offset of area with free space */
int slotsize; /* size of area at slotoffset */
int slotfreespace; /* amount of space free in slot */
int slotneeded; /* size of the entry we're seeking */
int numdirpasses; /* strategy for directory search */
doff_t endsearch; /* offset to end directory search */
doff_t prevoff; /* prev entry dp->i_offset */
struct vnode *pdp; /* saved dp during symlink work */
struct vnode *tdp; /* returned by VFS_VGET */
doff_t enduseful; /* pointer past last used dir slot */
u_long bmask; /* block offset mask */
int lockparent; /* 1 => lockparent flag is set */
int wantparent; /* 1 => wantparent or lockparent flag */
int namlen, error;
struct vnode **vpp = ap->a_vpp;
struct componentname *cnp = ap->a_cnp;
struct ucred *cred = cnp->cn_cred;
int flags = cnp->cn_flags;
int nameiop = cnp->cn_nameiop;
struct thread *td = cnp->cn_thread;
int DIRBLKSIZ = VTOI(ap->a_dvp)->i_e2fs->s_blocksize;
bp = NULL;
slotoffset = -1;
*vpp = NULL;
vdp = ap->a_dvp;
dp = VTOI(vdp);
lockparent = flags & LOCKPARENT;
wantparent = flags & (LOCKPARENT|WANTPARENT);
/*
* We now have a segment name to search for, and a directory to search.
*/
/*
* Suppress search for slots unless creating
* file and at end of pathname, in which case
* we watch for a place to put the new file in
* case it doesn't already exist.
*/
slotstatus = FOUND;
slotfreespace = slotsize = slotneeded = 0;
if ((nameiop == CREATE || nameiop == RENAME) &&
(flags & ISLASTCN)) {
slotstatus = NONE;
slotneeded = EXT2_DIR_REC_LEN(cnp->cn_namelen);
/* was
slotneeded = (sizeof(struct direct) - MAXNAMLEN +
cnp->cn_namelen + 3) &~ 3; */
}
/*
* If there is cached information on a previous search of
* this directory, pick up where we last left off.
* We cache only lookups as these are the most common
* and have the greatest payoff. Caching CREATE has little
* benefit as it usually must search the entire directory
* to determine that the entry does not exist. Caching the
* location of the last DELETE or RENAME has not reduced
* profiling time and hence has been removed in the interest
* of simplicity.
*/
bmask = VFSTOEXT2(vdp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
if (nameiop != LOOKUP || dp->i_diroff == 0 ||
dp->i_diroff > dp->i_size) {
entryoffsetinblock = 0;
dp->i_offset = 0;
numdirpasses = 1;
} else {
dp->i_offset = dp->i_diroff;
if ((entryoffsetinblock = dp->i_offset & bmask) &&
(error = ext2_blkatoff(vdp, (off_t)dp->i_offset, NULL,
&bp)))
return (error);
numdirpasses = 2;
nchstats.ncs_2passes++;
}
prevoff = dp->i_offset;
endsearch = roundup(dp->i_size, DIRBLKSIZ);
enduseful = 0;
searchloop:
while (dp->i_offset < endsearch) {
/*
* If necessary, get the next directory block.
*/
if ((dp->i_offset & bmask) == 0) {
if (bp != NULL)
brelse(bp);
if ((error =
ext2_blkatoff(vdp, (off_t)dp->i_offset, NULL,
&bp)) != 0)
return (error);
entryoffsetinblock = 0;
}
/*
* If still looking for a slot, and at a DIRBLKSIZE
* boundary, have to start looking for free space again.
*/
if (slotstatus == NONE &&
(entryoffsetinblock & (DIRBLKSIZ - 1)) == 0) {
slotoffset = -1;
slotfreespace = 0;
}
/*
* Get pointer to next entry.
* Full validation checks are slow, so we only check
* enough to insure forward progress through the
* directory. Complete checks can be run by setting
* "vfs.e2fs.dirchk" to be true.
*/
ep = (struct ext2_dir_entry_2 *)
((char *)bp->b_data + entryoffsetinblock);
if (ep->rec_len == 0 ||
(dirchk && ext2_dirbadentry(vdp, ep, entryoffsetinblock))) {
int i;
ext2_dirbad(dp, dp->i_offset, "mangled entry");
i = DIRBLKSIZ - (entryoffsetinblock & (DIRBLKSIZ - 1));
dp->i_offset += i;
entryoffsetinblock += i;
continue;
}
/*
* If an appropriate sized slot has not yet been found,
* check to see if one is available. Also accumulate space
* in the current block so that we can determine if
* compaction is viable.
*/
if (slotstatus != FOUND) {
int size = ep->rec_len;
if (ep->inode != 0)
size -= EXT2_DIR_REC_LEN(ep->name_len);
if (size > 0) {
if (size >= slotneeded) {
slotstatus = FOUND;
slotoffset = dp->i_offset;
slotsize = ep->rec_len;
} else if (slotstatus == NONE) {
slotfreespace += size;
if (slotoffset == -1)
slotoffset = dp->i_offset;
if (slotfreespace >= slotneeded) {
slotstatus = COMPACT;
slotsize = dp->i_offset +
ep->rec_len - slotoffset;
}
}
}
}
/*
* Check for a name match.
*/
if (ep->inode) {
namlen = ep->name_len;
if (namlen == cnp->cn_namelen &&
!bcmp(cnp->cn_nameptr, ep->name,
(unsigned)namlen)) {
/*
* Save directory entry's inode number and
* reclen in ndp->ni_ufs area, and release
* directory buffer.
*/
dp->i_ino = ep->inode;
dp->i_reclen = ep->rec_len;
brelse(bp);
goto found;
}
}
prevoff = dp->i_offset;
dp->i_offset += ep->rec_len;
entryoffsetinblock += ep->rec_len;
if (ep->inode)
enduseful = dp->i_offset;
}
/* notfound: */
/*
* If we started in the middle of the directory and failed
* to find our target, we must check the beginning as well.
*/
if (numdirpasses == 2) {
numdirpasses--;
dp->i_offset = 0;
endsearch = dp->i_diroff;
goto searchloop;
}
if (bp != NULL)
brelse(bp);
/*
* If creating, and at end of pathname and current
* directory has not been removed, then can consider
* allowing file to be created.
*/
if ((nameiop == CREATE || nameiop == RENAME) &&
(flags & ISLASTCN) && dp->i_nlink != 0) {
/*
* Access for write is interpreted as allowing
* creation of files in the directory.
*/
if ((error = VOP_ACCESS(vdp, VWRITE, cred, cnp->cn_thread)) != 0)
return (error);
/*
* Return an indication of where the new directory
* entry should be put. If we didn't find a slot,
* then set dp->i_count to 0 indicating
* that the new slot belongs at the end of the
* directory. If we found a slot, then the new entry
* can be put in the range from dp->i_offset to
* dp->i_offset + dp->i_count.
*/
if (slotstatus == NONE) {
dp->i_offset = roundup(dp->i_size, DIRBLKSIZ);
dp->i_count = 0;
enduseful = dp->i_offset;
} else {
dp->i_offset = slotoffset;
dp->i_count = slotsize;
if (enduseful < slotoffset + slotsize)
enduseful = slotoffset + slotsize;
}
dp->i_endoff = roundup(enduseful, DIRBLKSIZ);
dp->i_flag |= IN_CHANGE | IN_UPDATE;
/*
* We return with the directory locked, so that
* the parameters we set up above will still be
* valid if we actually decide to do a direnter().
* We return ni_vp == NULL to indicate that the entry
* does not currently exist; we leave a pointer to
* the (locked) directory inode in ndp->ni_dvp.
* The pathname buffer is saved so that the name
* can be obtained later.
*
* NB - if the directory is unlocked, then this
* information cannot be used.
*/
cnp->cn_flags |= SAVENAME;
if (!lockparent)
VOP_UNLOCK(vdp, 0, td);
return (EJUSTRETURN);
}
/*
* Insert name into cache (as non-existent) if appropriate.
*/
if ((cnp->cn_flags & MAKEENTRY) && nameiop != CREATE)
cache_enter(vdp, *vpp, cnp);
return (ENOENT);
found:
if (numdirpasses == 2)
nchstats.ncs_pass2++;
/*
* Check that directory length properly reflects presence
* of this entry.
*/
if (entryoffsetinblock + EXT2_DIR_REC_LEN(ep->name_len)
> dp->i_size) {
ext2_dirbad(dp, dp->i_offset, "i_size too small");
dp->i_size = entryoffsetinblock+EXT2_DIR_REC_LEN(ep->name_len);
dp->i_flag |= IN_CHANGE | IN_UPDATE;
}
/*
* Found component in pathname.
* If the final component of path name, save information
* in the cache as to where the entry was found.
*/
if ((flags & ISLASTCN) && nameiop == LOOKUP)
dp->i_diroff = dp->i_offset &~ (DIRBLKSIZ - 1);
/*
* If deleting, and at end of pathname, return
* parameters which can be used to remove file.
* If the wantparent flag isn't set, we return only
* the directory (in ndp->ni_dvp), otherwise we go
* on and lock the inode, being careful with ".".
*/
if (nameiop == DELETE && (flags & ISLASTCN)) {
/*
* Write access to directory required to delete files.
*/
if ((error = VOP_ACCESS(vdp, VWRITE, cred, cnp->cn_thread)) != 0)
return (error);
/*
* Return pointer to current entry in dp->i_offset,
* and distance past previous entry (if there
* is a previous entry in this block) in dp->i_count.
* Save directory inode pointer in ndp->ni_dvp for dirremove().
*/
if ((dp->i_offset & (DIRBLKSIZ - 1)) == 0)
dp->i_count = 0;
else
dp->i_count = dp->i_offset - prevoff;
if (dp->i_number == dp->i_ino) {
VREF(vdp);
*vpp = vdp;
return (0);
}
if ((error = VFS_VGET(vdp->v_mount, dp->i_ino, LK_EXCLUSIVE,
&tdp)) != 0)
return (error);
/*
* If directory is "sticky", then user must own
* the directory, or the file in it, else she
* may not delete it (unless she's root). This
* implements append-only directories.
*/
if ((dp->i_mode & ISVTX) &&
cred->cr_uid != 0 &&
cred->cr_uid != dp->i_uid &&
VTOI(tdp)->i_uid != cred->cr_uid) {
vput(tdp);
return (EPERM);
}
*vpp = tdp;
if (!lockparent)
VOP_UNLOCK(vdp, 0, td);
return (0);
}
/*
* If rewriting (RENAME), return the inode and the
* information required to rewrite the present directory
* Must get inode of directory entry to verify it's a
* regular file, or empty directory.
*/
if (nameiop == RENAME && wantparent &&
(flags & ISLASTCN)) {
if ((error = VOP_ACCESS(vdp, VWRITE, cred, cnp->cn_thread)) != 0)
return (error);
/*
* Careful about locking second inode.
* This can only occur if the target is ".".
*/
if (dp->i_number == dp->i_ino)
return (EISDIR);
if ((error = VFS_VGET(vdp->v_mount, dp->i_ino, LK_EXCLUSIVE,
&tdp)) != 0)
return (error);
*vpp = tdp;
cnp->cn_flags |= SAVENAME;
if (!lockparent)
VOP_UNLOCK(vdp, 0, td);
return (0);
}
/*
* Step through the translation in the name. We do not `vput' the
* directory because we may need it again if a symbolic link
* is relative to the current directory. Instead we save it
* unlocked as "pdp". We must get the target inode before unlocking
* the directory to insure that the inode will not be removed
* before we get it. We prevent deadlock by always fetching
* inodes from the root, moving down the directory tree. Thus
* when following backward pointers ".." we must unlock the
* parent directory before getting the requested directory.
* There is a potential race condition here if both the current
* and parent directories are removed before the VFS_VGET for the
* inode associated with ".." returns. We hope that this occurs
* infrequently since we cannot avoid this race condition without
* implementing a sophisticated deadlock detection algorithm.
* Note also that this simple deadlock detection scheme will not
* work if the file system has any hard links other than ".."
* that point backwards in the directory structure.
*/
pdp = vdp;
if (flags & ISDOTDOT) {
VOP_UNLOCK(pdp, 0, td); /* race to get the inode */
if ((error = VFS_VGET(vdp->v_mount, dp->i_ino, LK_EXCLUSIVE,
&tdp)) != 0) {
vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY, td);
return (error);
}
if (lockparent && (flags & ISLASTCN) &&
(error = vn_lock(pdp, LK_EXCLUSIVE, td))) {
vput(tdp);
return (error);
}
*vpp = tdp;
} else if (dp->i_number == dp->i_ino) {
VREF(vdp); /* we want ourself, ie "." */
*vpp = vdp;
} else {
if ((error = VFS_VGET(vdp->v_mount, dp->i_ino, LK_EXCLUSIVE,
&tdp)) != 0)
return (error);
if (!lockparent || !(flags & ISLASTCN))
VOP_UNLOCK(pdp, 0, td);
*vpp = tdp;
}
/*
* Insert name into cache if appropriate.
*/
if (cnp->cn_flags & MAKEENTRY)
cache_enter(vdp, *vpp, cnp);
return (0);
}
void
ext2_dirbad(ip, offset, how)
struct inode *ip;
doff_t offset;
char *how;
{
struct mount *mp;
mp = ITOV(ip)->v_mount;
(void)printf("%s: bad dir ino %lu at offset %ld: %s\n",
mp->mnt_stat.f_mntonname, (u_long)ip->i_number, (long)offset, how);
if ((mp->mnt_flag & MNT_RDONLY) == 0)
panic("ext2_dirbad: bad dir");
}
/*
* Do consistency checking on a directory entry:
* record length must be multiple of 4
* entry must fit in rest of its DIRBLKSIZ block
* record must be large enough to contain entry
* name is not longer than MAXNAMLEN
* name must be as long as advertised, and null terminated
*/
/*
* changed so that it confirms to ext2_check_dir_entry
*/
static int
ext2_dirbadentry(dp, de, entryoffsetinblock)
struct vnode *dp;
struct ext2_dir_entry_2 *de;
int entryoffsetinblock;
{
int DIRBLKSIZ = VTOI(dp)->i_e2fs->s_blocksize;
char * error_msg = NULL;
if (de->rec_len < EXT2_DIR_REC_LEN(1))
error_msg = "rec_len is smaller than minimal";
else if (de->rec_len % 4 != 0)
error_msg = "rec_len % 4 != 0";
else if (de->rec_len < EXT2_DIR_REC_LEN(de->name_len))
error_msg = "reclen is too small for name_len";
else if (entryoffsetinblock + de->rec_len > DIRBLKSIZ)
error_msg = "directory entry across blocks";
/* else LATER
if (de->inode > dir->i_sb->u.ext2_sb.s_es->s_inodes_count)
error_msg = "inode out of bounds";
*/
if (error_msg != NULL) {
printf("bad directory entry: %s\n", error_msg);
printf("offset=%d, inode=%lu, rec_len=%u, name_len=%u\n",
entryoffsetinblock, (unsigned long)de->inode,
de->rec_len, de->name_len);
}
return error_msg == NULL ? 0 : 1;
}
/*
* Write a directory entry after a call to namei, using the parameters
* that it left in nameidata. The argument ip is the inode which the new
* directory entry will refer to. Dvp is a pointer to the directory to
* be written, which was left locked by namei. Remaining parameters
* (dp->i_offset, dp->i_count) indicate how the space for the new
* entry is to be obtained.
*/
int
ext2_direnter(ip, dvp, cnp)
struct inode *ip;
struct vnode *dvp;
struct componentname *cnp;
{
struct ext2_dir_entry_2 *ep, *nep;
struct inode *dp;
struct buf *bp;
struct ext2_dir_entry_2 newdir;
struct iovec aiov;
struct uio auio;
u_int dsize;
int error, loc, newentrysize, spacefree;
char *dirbuf;
int DIRBLKSIZ = ip->i_e2fs->s_blocksize;
#if DIAGNOSTIC
if ((cnp->cn_flags & SAVENAME) == 0)
panic("direnter: missing name");
#endif
dp = VTOI(dvp);
newdir.inode = ip->i_number;
newdir.name_len = cnp->cn_namelen;
if (EXT2_HAS_INCOMPAT_FEATURE(ip->i_e2fs->s_es,
EXT2_FEATURE_INCOMPAT_FILETYPE))
newdir.file_type = DTTOFT(IFTODT(ip->i_mode));
else
newdir.file_type = EXT2_FT_UNKNOWN;
bcopy(cnp->cn_nameptr, newdir.name, (unsigned)cnp->cn_namelen + 1);
newentrysize = EXT2_DIR_REC_LEN(newdir.name_len);
if (dp->i_count == 0) {
/*
* If dp->i_count is 0, then namei could find no
* space in the directory. Here, dp->i_offset will
* be on a directory block boundary and we will write the
* new entry into a fresh block.
*/
if (dp->i_offset & (DIRBLKSIZ - 1))
panic("ext2_direnter: newblk");
auio.uio_offset = dp->i_offset;
newdir.rec_len = DIRBLKSIZ;
auio.uio_resid = newentrysize;
aiov.iov_len = newentrysize;
aiov.iov_base = (caddr_t)&newdir;
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
auio.uio_rw = UIO_WRITE;
auio.uio_segflg = UIO_SYSSPACE;
auio.uio_td = (struct thread *)0;
error = VOP_WRITE(dvp, &auio, IO_SYNC, cnp->cn_cred);
if (DIRBLKSIZ >
VFSTOEXT2(dvp->v_mount)->um_mountp->mnt_stat.f_bsize)
/* XXX should grow with balloc() */
panic("ext2_direnter: frag size");
else if (!error) {
dp->i_size = roundup(dp->i_size, DIRBLKSIZ);
dp->i_flag |= IN_CHANGE;
}
return (error);
}
/*
* If dp->i_count is non-zero, then namei found space
* for the new entry in the range dp->i_offset to
* dp->i_offset + dp->i_count in the directory.
* To use this space, we may have to compact the entries located
* there, by copying them together towards the beginning of the
* block, leaving the free space in one usable chunk at the end.
*/
/*
* Increase size of directory if entry eats into new space.
* This should never push the size past a new multiple of
* DIRBLKSIZE.
*
* N.B. - THIS IS AN ARTIFACT OF 4.2 AND SHOULD NEVER HAPPEN.
*/
if (dp->i_offset + dp->i_count > dp->i_size)
dp->i_size = dp->i_offset + dp->i_count;
/*
* Get the block containing the space for the new directory entry.
*/
if ((error = ext2_blkatoff(dvp, (off_t)dp->i_offset, &dirbuf,
&bp)) != 0)
return (error);
/*
* Find space for the new entry. In the simple case, the entry at
* offset base will have the space. If it does not, then namei
* arranged that compacting the region dp->i_offset to
* dp->i_offset + dp->i_count would yield the
* space.
*/
ep = (struct ext2_dir_entry_2 *)dirbuf;
dsize = EXT2_DIR_REC_LEN(ep->name_len);
spacefree = ep->rec_len - dsize;
for (loc = ep->rec_len; loc < dp->i_count; ) {
nep = (struct ext2_dir_entry_2 *)(dirbuf + loc);
if (ep->inode) {
/* trim the existing slot */
ep->rec_len = dsize;
ep = (struct ext2_dir_entry_2 *)((char *)ep + dsize);
} else {
/* overwrite; nothing there; header is ours */
spacefree += dsize;
}
dsize = EXT2_DIR_REC_LEN(nep->name_len);
spacefree += nep->rec_len - dsize;
loc += nep->rec_len;
bcopy((caddr_t)nep, (caddr_t)ep, dsize);
}
/*
* Update the pointer fields in the previous entry (if any),
* copy in the new entry, and write out the block.
*/
if (ep->inode == 0) {
if (spacefree + dsize < newentrysize)
panic("ext2_direnter: compact1");
newdir.rec_len = spacefree + dsize;
} else {
if (spacefree < newentrysize)
panic("ext2_direnter: compact2");
newdir.rec_len = spacefree;
ep->rec_len = dsize;
ep = (struct ext2_dir_entry_2 *)((char *)ep + dsize);
}
bcopy((caddr_t)&newdir, (caddr_t)ep, (u_int)newentrysize);
error = BUF_WRITE(bp);
dp->i_flag |= IN_CHANGE | IN_UPDATE;
if (!error && dp->i_endoff && dp->i_endoff < dp->i_size)
error = ext2_truncate(dvp, (off_t)dp->i_endoff, IO_SYNC,
cnp->cn_cred, cnp->cn_thread);
return (error);
}
/*
* Remove a directory entry after a call to namei, using
* the parameters which it left in nameidata. The entry
* dp->i_offset contains the offset into the directory of the
* entry to be eliminated. The dp->i_count field contains the
* size of the previous record in the directory. If this
* is 0, the first entry is being deleted, so we need only
* zero the inode number to mark the entry as free. If the
* entry is not the first in the directory, we must reclaim
* the space of the now empty record by adding the record size
* to the size of the previous entry.
*/
int
ext2_dirremove(dvp, cnp)
struct vnode *dvp;
struct componentname *cnp;
{
struct inode *dp;
struct ext2_dir_entry_2 *ep;
struct buf *bp;
int error;
dp = VTOI(dvp);
if (dp->i_count == 0) {
/*
* First entry in block: set d_ino to zero.
*/
if ((error =
ext2_blkatoff(dvp, (off_t)dp->i_offset, (char **)&ep,
&bp)) != 0)
return (error);
ep->inode = 0;
error = BUF_WRITE(bp);
dp->i_flag |= IN_CHANGE | IN_UPDATE;
return (error);
}
/*
* Collapse new free space into previous entry.
*/
if ((error = ext2_blkatoff(dvp, (off_t)(dp->i_offset - dp->i_count),
(char **)&ep, &bp)) != 0)
return (error);
ep->rec_len += dp->i_reclen;
error = BUF_WRITE(bp);
dp->i_flag |= IN_CHANGE | IN_UPDATE;
return (error);
}
/*
* Rewrite an existing directory entry to point at the inode
* supplied. The parameters describing the directory entry are
* set up by a call to namei.
*/
int
ext2_dirrewrite(dp, ip, cnp)
struct inode *dp, *ip;
struct componentname *cnp;
{
struct buf *bp;
struct ext2_dir_entry_2 *ep;
struct vnode *vdp = ITOV(dp);
int error;
if ((error = ext2_blkatoff(vdp, (off_t)dp->i_offset, (char **)&ep,
&bp)) != 0)
return (error);
ep->inode = ip->i_number;
if (EXT2_HAS_INCOMPAT_FEATURE(ip->i_e2fs->s_es,
EXT2_FEATURE_INCOMPAT_FILETYPE))
ep->file_type = DTTOFT(IFTODT(ip->i_mode));
else
ep->file_type = EXT2_FT_UNKNOWN;
error = BUF_WRITE(bp);
dp->i_flag |= IN_CHANGE | IN_UPDATE;
return (error);
}
/*
* Check if a directory is empty or not.
* Inode supplied must be locked.
*
* Using a struct dirtemplate here is not precisely
* what we want, but better than using a struct direct.
*
* NB: does not handle corrupted directories.
*/
int
ext2_dirempty(ip, parentino, cred)
struct inode *ip;
ino_t parentino;
struct ucred *cred;
{
off_t off;
struct dirtemplate dbuf;
struct ext2_dir_entry_2 *dp = (struct ext2_dir_entry_2 *)&dbuf;
int error, count, namlen;
#define MINDIRSIZ (sizeof (struct dirtemplate) / 2)
for (off = 0; off < ip->i_size; off += dp->rec_len) {
error = vn_rdwr(UIO_READ, ITOV(ip), (caddr_t)dp, MINDIRSIZ,
off, UIO_SYSSPACE, IO_NODELOCKED | IO_NOMACCHECK, cred,
NOCRED, &count, (struct thread *)0);
/*
* Since we read MINDIRSIZ, residual must
* be 0 unless we're at end of file.
*/
if (error || count != 0)
return (0);
/* avoid infinite loops */
if (dp->rec_len == 0)
return (0);
/* skip empty entries */
if (dp->inode == 0)
continue;
/* accept only "." and ".." */
namlen = dp->name_len;
if (namlen > 2)
return (0);
if (dp->name[0] != '.')
return (0);
/*
* At this point namlen must be 1 or 2.
* 1 implies ".", 2 implies ".." if second
* char is also "."
*/
if (namlen == 1)
continue;
if (dp->name[1] == '.' && dp->inode == parentino)
continue;
return (0);
}
return (1);
}
/*
* Check if source directory is in the path of the target directory.
* Target is supplied locked, source is unlocked.
* The target is always vput before returning.
*/
int
ext2_checkpath(source, target, cred)
struct inode *source, *target;
struct ucred *cred;
{
struct vnode *vp;
int error, rootino, namlen;
struct dirtemplate dirbuf;
vp = ITOV(target);
if (target->i_number == source->i_number) {
error = EEXIST;
goto out;
}
rootino = ROOTINO;
error = 0;
if (target->i_number == rootino)
goto out;
for (;;) {
if (vp->v_type != VDIR) {
error = ENOTDIR;
break;
}
error = vn_rdwr(UIO_READ, vp, (caddr_t)&dirbuf,
sizeof (struct dirtemplate), (off_t)0, UIO_SYSSPACE,
IO_NODELOCKED | IO_NOMACCHECK, cred, NOCRED, (int *)0,
(struct thread *)0);
if (error != 0)
break;
namlen = dirbuf.dotdot_type; /* like ufs little-endian */
if (namlen != 2 ||
dirbuf.dotdot_name[0] != '.' ||
dirbuf.dotdot_name[1] != '.') {
error = ENOTDIR;
break;
}
if (dirbuf.dotdot_ino == source->i_number) {
error = EINVAL;
break;
}
if (dirbuf.dotdot_ino == rootino)
break;
vput(vp);
if ((error = VFS_VGET(vp->v_mount, dirbuf.dotdot_ino,
LK_EXCLUSIVE, &vp)) != 0) {
vp = NULL;
break;
}
}
out:
if (error == ENOTDIR)
printf("checkpath: .. not a directory\n");
if (vp != NULL)
vput(vp);
return (error);
}
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