kernel-ark/fs/nfsd/nfsfh.c
NeilBrown b41eeef14d knfsd: avoid Oops if buggy userspace performs confusing filehandle->dentry mapping
When a lookup request arrives, nfsd uses information provided by userspace
(mountd) to find the right filesystem.

It then assumes that the same filehandle type as the incoming filehandle can
be used to create an outgoing filehandle.

However if mountd is buggy, or maybe just being creative, the filesystem may
not support that filesystem type, and the kernel could oops, particularly if
'ex_uuid' is NULL but a FSID_UUID* filehandle type is used.

So add some proper checking that the fsid version/type from the incoming
filehandle is actually supportable, and ignore that information if it isn't
supportable.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09 12:30:54 -07:00

578 lines
14 KiB
C

/*
* linux/fs/nfsd/nfsfh.c
*
* NFS server file handle treatment.
*
* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
* Portions Copyright (C) 1999 G. Allen Morris III <gam3@acm.org>
* Extensive rewrite by Neil Brown <neilb@cse.unsw.edu.au> Southern-Spring 1999
* ... and again Southern-Winter 2001 to support export_operations
*/
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/unistd.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/dcache.h>
#include <linux/mount.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
#include <linux/nfsd/nfsd.h>
#define NFSDDBG_FACILITY NFSDDBG_FH
static int nfsd_nr_verified;
static int nfsd_nr_put;
extern struct export_operations export_op_default;
#define CALL(ops,fun) ((ops->fun)?(ops->fun):export_op_default.fun)
/*
* our acceptability function.
* if NOSUBTREECHECK, accept anything
* if not, require that we can walk up to exp->ex_dentry
* doing some checks on the 'x' bits
*/
static int nfsd_acceptable(void *expv, struct dentry *dentry)
{
struct svc_export *exp = expv;
int rv;
struct dentry *tdentry;
struct dentry *parent;
if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
return 1;
tdentry = dget(dentry);
while (tdentry != exp->ex_dentry && ! IS_ROOT(tdentry)) {
/* make sure parents give x permission to user */
int err;
parent = dget_parent(tdentry);
err = permission(parent->d_inode, MAY_EXEC, NULL);
if (err < 0) {
dput(parent);
break;
}
dput(tdentry);
tdentry = parent;
}
if (tdentry != exp->ex_dentry)
dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name);
rv = (tdentry == exp->ex_dentry);
dput(tdentry);
return rv;
}
/* Type check. The correct error return for type mismatches does not seem to be
* generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
* comment in the NFSv3 spec says this is incorrect (implementation notes for
* the write call).
*/
static inline __be32
nfsd_mode_check(struct svc_rqst *rqstp, umode_t mode, int type)
{
/* Type can be negative when creating hardlinks - not to a dir */
if (type > 0 && (mode & S_IFMT) != type) {
if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
return nfserr_symlink;
else if (type == S_IFDIR)
return nfserr_notdir;
else if ((mode & S_IFMT) == S_IFDIR)
return nfserr_isdir;
else
return nfserr_inval;
}
if (type < 0 && (mode & S_IFMT) == -type) {
if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
return nfserr_symlink;
else if (type == -S_IFDIR)
return nfserr_isdir;
else
return nfserr_notdir;
}
return 0;
}
/*
* Perform sanity checks on the dentry in a client's file handle.
*
* Note that the file handle dentry may need to be freed even after
* an error return.
*
* This is only called at the start of an nfsproc call, so fhp points to
* a svc_fh which is all 0 except for the over-the-wire file handle.
*/
__be32
fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
{
struct knfsd_fh *fh = &fhp->fh_handle;
struct svc_export *exp = NULL;
struct dentry *dentry;
__be32 error = 0;
dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
if (!fhp->fh_dentry) {
__u32 *datap=NULL;
__u32 tfh[3]; /* filehandle fragment for oldstyle filehandles */
int fileid_type;
int data_left = fh->fh_size/4;
error = nfserr_stale;
if (rqstp->rq_client == NULL)
goto out;
if (rqstp->rq_vers > 2)
error = nfserr_badhandle;
if (rqstp->rq_vers == 4 && fh->fh_size == 0)
return nfserr_nofilehandle;
if (fh->fh_version == 1) {
int len;
datap = fh->fh_auth;
if (--data_left<0) goto out;
switch (fh->fh_auth_type) {
case 0: break;
default: goto out;
}
len = key_len(fh->fh_fsid_type) / 4;
if (len == 0) goto out;
if (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
/* deprecated, convert to type 3 */
len = key_len(FSID_ENCODE_DEV)/4;
fh->fh_fsid_type = FSID_ENCODE_DEV;
fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(fh->fh_fsid[1])));
fh->fh_fsid[1] = fh->fh_fsid[2];
}
if ((data_left -= len)<0) goto out;
exp = exp_find(rqstp->rq_client, fh->fh_fsid_type, datap, &rqstp->rq_chandle);
datap += len;
} else {
dev_t xdev;
ino_t xino;
if (fh->fh_size != NFS_FHSIZE)
goto out;
/* assume old filehandle format */
xdev = old_decode_dev(fh->ofh_xdev);
xino = u32_to_ino_t(fh->ofh_xino);
mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
exp = exp_find(rqstp->rq_client, FSID_DEV, tfh,
&rqstp->rq_chandle);
}
if (IS_ERR(exp) && (PTR_ERR(exp) == -EAGAIN
|| PTR_ERR(exp) == -ETIMEDOUT)) {
error = nfserrno(PTR_ERR(exp));
goto out;
}
error = nfserr_stale;
if (!exp || IS_ERR(exp))
goto out;
/* Check if the request originated from a secure port. */
error = nfserr_perm;
if (!rqstp->rq_secure && EX_SECURE(exp)) {
char buf[RPC_MAX_ADDRBUFLEN];
printk(KERN_WARNING
"nfsd: request from insecure port %s!\n",
svc_print_addr(rqstp, buf, sizeof(buf)));
goto out;
}
/* Set user creds for this exportpoint */
error = nfserrno(nfsd_setuser(rqstp, exp));
if (error)
goto out;
/*
* Look up the dentry using the NFS file handle.
*/
error = nfserr_stale;
if (rqstp->rq_vers > 2)
error = nfserr_badhandle;
if (fh->fh_version != 1) {
tfh[0] = fh->ofh_ino;
tfh[1] = fh->ofh_generation;
tfh[2] = fh->ofh_dirino;
datap = tfh;
data_left = 3;
if (fh->ofh_dirino == 0)
fileid_type = 1;
else
fileid_type = 2;
} else
fileid_type = fh->fh_fileid_type;
if (fileid_type == 0)
dentry = dget(exp->ex_dentry);
else {
struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
dentry = CALL(nop,decode_fh)(exp->ex_mnt->mnt_sb,
datap, data_left,
fileid_type,
nfsd_acceptable, exp);
}
if (dentry == NULL)
goto out;
if (IS_ERR(dentry)) {
if (PTR_ERR(dentry) != -EINVAL)
error = nfserrno(PTR_ERR(dentry));
goto out;
}
if (S_ISDIR(dentry->d_inode->i_mode) &&
(dentry->d_flags & DCACHE_DISCONNECTED)) {
printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
dentry->d_parent->d_name.name, dentry->d_name.name);
}
fhp->fh_dentry = dentry;
fhp->fh_export = exp;
nfsd_nr_verified++;
} else {
/* just rechecking permissions
* (e.g. nfsproc_create calls fh_verify, then nfsd_create does as well)
*/
dprintk("nfsd: fh_verify - just checking\n");
dentry = fhp->fh_dentry;
exp = fhp->fh_export;
/* Set user creds for this exportpoint; necessary even
* in the "just checking" case because this may be a
* filehandle that was created by fh_compose, and that
* is about to be used in another nfsv4 compound
* operation */
error = nfserrno(nfsd_setuser(rqstp, exp));
if (error)
goto out;
}
cache_get(&exp->h);
error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
if (error)
goto out;
/* Finally, check access permissions. */
error = nfsd_permission(exp, dentry, access);
if (error) {
dprintk("fh_verify: %s/%s permission failure, "
"acc=%x, error=%d\n",
dentry->d_parent->d_name.name,
dentry->d_name.name,
access, ntohl(error));
}
out:
if (exp && !IS_ERR(exp))
exp_put(exp);
if (error == nfserr_stale)
nfsdstats.fh_stale++;
return error;
}
/*
* Compose a file handle for an NFS reply.
*
* Note that when first composed, the dentry may not yet have
* an inode. In this case a call to fh_update should be made
* before the fh goes out on the wire ...
*/
static inline int _fh_update(struct dentry *dentry, struct svc_export *exp,
__u32 *datap, int *maxsize)
{
struct export_operations *nop = exp->ex_mnt->mnt_sb->s_export_op;
if (dentry == exp->ex_dentry) {
*maxsize = 0;
return 0;
}
return CALL(nop,encode_fh)(dentry, datap, maxsize,
!(exp->ex_flags&NFSEXP_NOSUBTREECHECK));
}
/*
* for composing old style file handles
*/
static inline void _fh_update_old(struct dentry *dentry,
struct svc_export *exp,
struct knfsd_fh *fh)
{
fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
fh->ofh_generation = dentry->d_inode->i_generation;
if (S_ISDIR(dentry->d_inode->i_mode) ||
(exp->ex_flags & NFSEXP_NOSUBTREECHECK))
fh->ofh_dirino = 0;
}
__be32
fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
struct svc_fh *ref_fh)
{
/* ref_fh is a reference file handle.
* if it is non-null and for the same filesystem, then we should compose
* a filehandle which is of the same version, where possible.
* Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
* Then create a 32byte filehandle using nfs_fhbase_old
*
*/
u8 version;
u8 fsid_type = 0;
struct inode * inode = dentry->d_inode;
struct dentry *parent = dentry->d_parent;
__u32 *datap;
dev_t ex_dev = exp->ex_dentry->d_inode->i_sb->s_dev;
int root_export = (exp->ex_dentry == exp->ex_dentry->d_sb->s_root);
dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
MAJOR(ex_dev), MINOR(ex_dev),
(long) exp->ex_dentry->d_inode->i_ino,
parent->d_name.name, dentry->d_name.name,
(inode ? inode->i_ino : 0));
/* Choose filehandle version and fsid type based on
* the reference filehandle (if it is in the same export)
* or the export options.
*/
retry:
version = 1;
if (ref_fh && ref_fh->fh_export == exp) {
version = ref_fh->fh_handle.fh_version;
fsid_type = ref_fh->fh_handle.fh_fsid_type;
if (ref_fh == fhp)
fh_put(ref_fh);
ref_fh = NULL;
switch (version) {
case 0xca:
fsid_type = FSID_DEV;
break;
case 1:
break;
default:
goto retry;
}
/* Need to check that this type works for this
* export point. As the fsid -> filesystem mapping
* was guided by user-space, there is no guarantee
* that the filesystem actually supports that fsid
* type. If it doesn't we loop around again without
* ref_fh set.
*/
switch(fsid_type) {
case FSID_DEV:
if (!old_valid_dev(ex_dev))
goto retry;
/* FALL THROUGH */
case FSID_MAJOR_MINOR:
case FSID_ENCODE_DEV:
if (!(exp->ex_dentry->d_inode->i_sb->s_type->fs_flags
& FS_REQUIRES_DEV))
goto retry;
break;
case FSID_NUM:
if (! (exp->ex_flags & NFSEXP_FSID))
goto retry;
break;
case FSID_UUID8:
case FSID_UUID16:
if (!root_export)
goto retry;
/* fall through */
case FSID_UUID4_INUM:
case FSID_UUID16_INUM:
if (exp->ex_uuid == NULL)
goto retry;
break;
}
} else if (exp->ex_uuid) {
if (fhp->fh_maxsize >= 64) {
if (root_export)
fsid_type = FSID_UUID16;
else
fsid_type = FSID_UUID16_INUM;
} else {
if (root_export)
fsid_type = FSID_UUID8;
else
fsid_type = FSID_UUID4_INUM;
}
} else if (exp->ex_flags & NFSEXP_FSID)
fsid_type = FSID_NUM;
else if (!old_valid_dev(ex_dev))
/* for newer device numbers, we must use a newer fsid format */
fsid_type = FSID_ENCODE_DEV;
else
fsid_type = FSID_DEV;
if (ref_fh == fhp)
fh_put(ref_fh);
if (fhp->fh_locked || fhp->fh_dentry) {
printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
parent->d_name.name, dentry->d_name.name);
}
if (fhp->fh_maxsize < NFS_FHSIZE)
printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
fhp->fh_maxsize,
parent->d_name.name, dentry->d_name.name);
fhp->fh_dentry = dget(dentry); /* our internal copy */
fhp->fh_export = exp;
cache_get(&exp->h);
if (version == 0xca) {
/* old style filehandle please */
memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
fhp->fh_handle.fh_size = NFS_FHSIZE;
fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
fhp->fh_handle.ofh_dev = old_encode_dev(ex_dev);
fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
fhp->fh_handle.ofh_xino =
ino_t_to_u32(exp->ex_dentry->d_inode->i_ino);
fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
if (inode)
_fh_update_old(dentry, exp, &fhp->fh_handle);
} else {
int len;
fhp->fh_handle.fh_version = 1;
fhp->fh_handle.fh_auth_type = 0;
datap = fhp->fh_handle.fh_auth+0;
fhp->fh_handle.fh_fsid_type = fsid_type;
mk_fsid(fsid_type, datap, ex_dev,
exp->ex_dentry->d_inode->i_ino,
exp->ex_fsid, exp->ex_uuid);
len = key_len(fsid_type);
datap += len/4;
fhp->fh_handle.fh_size = 4 + len;
if (inode) {
int size = (fhp->fh_maxsize-len-4)/4;
fhp->fh_handle.fh_fileid_type =
_fh_update(dentry, exp, datap, &size);
fhp->fh_handle.fh_size += size*4;
}
if (fhp->fh_handle.fh_fileid_type == 255)
return nfserr_opnotsupp;
}
nfsd_nr_verified++;
return 0;
}
/*
* Update file handle information after changing a dentry.
* This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
*/
__be32
fh_update(struct svc_fh *fhp)
{
struct dentry *dentry;
__u32 *datap;
if (!fhp->fh_dentry)
goto out_bad;
dentry = fhp->fh_dentry;
if (!dentry->d_inode)
goto out_negative;
if (fhp->fh_handle.fh_version != 1) {
_fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
} else {
int size;
if (fhp->fh_handle.fh_fileid_type != 0)
goto out;
datap = fhp->fh_handle.fh_auth+
fhp->fh_handle.fh_size/4 -1;
size = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
fhp->fh_handle.fh_fileid_type =
_fh_update(dentry, fhp->fh_export, datap, &size);
fhp->fh_handle.fh_size += size*4;
if (fhp->fh_handle.fh_fileid_type == 255)
return nfserr_opnotsupp;
}
out:
return 0;
out_bad:
printk(KERN_ERR "fh_update: fh not verified!\n");
goto out;
out_negative:
printk(KERN_ERR "fh_update: %s/%s still negative!\n",
dentry->d_parent->d_name.name, dentry->d_name.name);
goto out;
}
/*
* Release a file handle.
*/
void
fh_put(struct svc_fh *fhp)
{
struct dentry * dentry = fhp->fh_dentry;
struct svc_export * exp = fhp->fh_export;
if (dentry) {
fh_unlock(fhp);
fhp->fh_dentry = NULL;
dput(dentry);
#ifdef CONFIG_NFSD_V3
fhp->fh_pre_saved = 0;
fhp->fh_post_saved = 0;
#endif
nfsd_nr_put++;
}
if (exp) {
cache_put(&exp->h, &svc_export_cache);
fhp->fh_export = NULL;
}
return;
}
/*
* Shorthand for dprintk()'s
*/
char * SVCFH_fmt(struct svc_fh *fhp)
{
struct knfsd_fh *fh = &fhp->fh_handle;
static char buf[80];
sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
fh->fh_size,
fh->fh_base.fh_pad[0],
fh->fh_base.fh_pad[1],
fh->fh_base.fh_pad[2],
fh->fh_base.fh_pad[3],
fh->fh_base.fh_pad[4],
fh->fh_base.fh_pad[5]);
return buf;
}
enum fsid_source fsid_source(struct svc_fh *fhp)
{
if (fhp->fh_handle.fh_version != 1)
return FSIDSOURCE_DEV;
switch(fhp->fh_handle.fh_fsid_type) {
case FSID_DEV:
case FSID_ENCODE_DEV:
case FSID_MAJOR_MINOR:
return FSIDSOURCE_DEV;
case FSID_NUM:
return FSIDSOURCE_FSID;
default:
if (fhp->fh_export->ex_flags & NFSEXP_FSID)
return FSIDSOURCE_FSID;
else
return FSIDSOURCE_UUID;
}
}