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freebsd/sys/kern/vfs_export.c
John Baldwin 593efaf9f7 Further refine the handling of stop signals in the NFS client. The
changes in r246417 were incomplete as they did not add explicit calls to
sigdeferstop() around all the places that previously passed SBDRY to
_sleep().  In addition, nfs_getcacheblk() could trigger a write RPC from
getblk() resulting in sigdeferstop() recursing.  Rather than manually
deferring stop signals in specific places, change the VFS_*() and VOP_*()
methods to defer stop signals for filesystems which request this behavior
via a new VFCF_SBDRY flag.  Note that this has to be a VFC flag rather than
a MNTK flag so that it works properly with VFS_MOUNT() when the mount is
not yet fully constructed.  For now, only the NFS clients are set this new
flag in VFS_SET().

A few other related changes:
- Add an assertion to ensure that TDF_SBDRY doesn't leak to userland.
- When a lookup request uses VOP_READLINK() to follow a symlink, mark
  the request as being on behalf of the thread performing the lookup
  (cnp_thread) rather than using a NULL thread pointer.  This causes
  NFS to properly handle signals during this VOP on an interruptible
  mount.

PR:		kern/176179
Reported by:	Russell Cattelan (sigdeferstop() recursion)
Reviewed by:	kib
MFC after:	1 month
2013-02-21 19:02:50 +00:00

494 lines
14 KiB
C

/*-
* 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.
* 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.
*
* @(#)vfs_subr.c 8.31 (Berkeley) 5/26/95
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/dirent.h>
#include <sys/domain.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/rwlock.h>
#include <sys/refcount.h>
#include <sys/signalvar.h>
#include <sys/socket.h>
#include <sys/systm.h>
#include <sys/vnode.h>
#include <net/radix.h>
static MALLOC_DEFINE(M_NETADDR, "export_host", "Export host address structure");
static void vfs_free_addrlist(struct netexport *nep);
static int vfs_free_netcred(struct radix_node *rn, void *w);
static int vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
struct export_args *argp);
static struct netcred *vfs_export_lookup(struct mount *, struct sockaddr *);
/*
* Network address lookup element
*/
struct netcred {
struct radix_node netc_rnodes[2];
int netc_exflags;
struct ucred *netc_anon;
int netc_numsecflavors;
int netc_secflavors[MAXSECFLAVORS];
};
/*
* Network export information
*/
struct netexport {
struct netcred ne_defexported; /* Default export */
struct radix_node_head *ne_rtable[AF_MAX+1]; /* Individual exports */
};
/*
* Build hash lists of net addresses and hang them off the mount point.
* Called by vfs_export() to set up the lists of export addresses.
*/
static int
vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
struct export_args *argp)
{
register struct netcred *np;
register struct radix_node_head *rnh;
register int i;
struct radix_node *rn;
struct sockaddr *saddr, *smask = 0;
struct domain *dom;
int error;
/*
* XXX: This routine converts from a `struct xucred'
* (argp->ex_anon) to a `struct ucred' (np->netc_anon). This
* operation is questionable; for example, what should be done
* with fields like cr_uidinfo and cr_prison? Currently, this
* routine does not touch them (leaves them as NULL).
*/
if (argp->ex_anon.cr_version != XUCRED_VERSION) {
vfs_mount_error(mp, "ex_anon.cr_version: %d != %d",
argp->ex_anon.cr_version, XUCRED_VERSION);
return (EINVAL);
}
if (argp->ex_addrlen == 0) {
if (mp->mnt_flag & MNT_DEFEXPORTED) {
vfs_mount_error(mp,
"MNT_DEFEXPORTED already set for mount %p", mp);
return (EPERM);
}
np = &nep->ne_defexported;
np->netc_exflags = argp->ex_flags;
np->netc_anon = crget();
np->netc_anon->cr_uid = argp->ex_anon.cr_uid;
crsetgroups(np->netc_anon, argp->ex_anon.cr_ngroups,
argp->ex_anon.cr_groups);
np->netc_anon->cr_prison = &prison0;
prison_hold(np->netc_anon->cr_prison);
np->netc_numsecflavors = argp->ex_numsecflavors;
bcopy(argp->ex_secflavors, np->netc_secflavors,
sizeof(np->netc_secflavors));
MNT_ILOCK(mp);
mp->mnt_flag |= MNT_DEFEXPORTED;
MNT_IUNLOCK(mp);
return (0);
}
#if MSIZE <= 256
if (argp->ex_addrlen > MLEN) {
vfs_mount_error(mp, "ex_addrlen %d is greater than %d",
argp->ex_addrlen, MLEN);
return (EINVAL);
}
#endif
i = sizeof(struct netcred) + argp->ex_addrlen + argp->ex_masklen;
np = (struct netcred *) malloc(i, M_NETADDR, M_WAITOK | M_ZERO);
saddr = (struct sockaddr *) (np + 1);
if ((error = copyin(argp->ex_addr, saddr, argp->ex_addrlen)))
goto out;
if (saddr->sa_family == AF_UNSPEC || saddr->sa_family > AF_MAX) {
error = EINVAL;
vfs_mount_error(mp, "Invalid saddr->sa_family: %d");
goto out;
}
if (saddr->sa_len > argp->ex_addrlen)
saddr->sa_len = argp->ex_addrlen;
if (argp->ex_masklen) {
smask = (struct sockaddr *)((caddr_t)saddr + argp->ex_addrlen);
error = copyin(argp->ex_mask, smask, argp->ex_masklen);
if (error)
goto out;
if (smask->sa_len > argp->ex_masklen)
smask->sa_len = argp->ex_masklen;
}
i = saddr->sa_family;
if ((rnh = nep->ne_rtable[i]) == NULL) {
/*
* Seems silly to initialize every AF when most are not used,
* do so on demand here
*/
for (dom = domains; dom; dom = dom->dom_next) {
KASSERT(((i == AF_INET) || (i == AF_INET6)),
("unexpected protocol in vfs_hang_addrlist"));
if (dom->dom_family == i && dom->dom_rtattach) {
/*
* XXX MRT
* The INET and INET6 domains know the
* offset already. We don't need to send it
* So we just use it as a flag to say that
* we are or are not setting up a real routing
* table. Only IP and IPV6 need have this
* be 0 so all other protocols can stay the
* same (ABI compatible).
*/
dom->dom_rtattach(
(void **) &nep->ne_rtable[i], 0);
break;
}
}
if ((rnh = nep->ne_rtable[i]) == NULL) {
error = ENOBUFS;
vfs_mount_error(mp, "%s %s %d",
"Unable to initialize radix node head ",
"for address family", i);
goto out;
}
}
RADIX_NODE_HEAD_LOCK(rnh);
rn = (*rnh->rnh_addaddr)(saddr, smask, rnh, np->netc_rnodes);
RADIX_NODE_HEAD_UNLOCK(rnh);
if (rn == NULL || np != (struct netcred *)rn) { /* already exists */
error = EPERM;
vfs_mount_error(mp, "Invalid radix node head, rn: %p %p",
rn, np);
goto out;
}
np->netc_exflags = argp->ex_flags;
np->netc_anon = crget();
np->netc_anon->cr_uid = argp->ex_anon.cr_uid;
crsetgroups(np->netc_anon, argp->ex_anon.cr_ngroups,
argp->ex_anon.cr_groups);
np->netc_anon->cr_prison = &prison0;
prison_hold(np->netc_anon->cr_prison);
np->netc_numsecflavors = argp->ex_numsecflavors;
bcopy(argp->ex_secflavors, np->netc_secflavors,
sizeof(np->netc_secflavors));
return (0);
out:
free(np, M_NETADDR);
return (error);
}
/* Helper for vfs_free_addrlist. */
/* ARGSUSED */
static int
vfs_free_netcred(struct radix_node *rn, void *w)
{
struct radix_node_head *rnh = (struct radix_node_head *) w;
struct ucred *cred;
(*rnh->rnh_deladdr) (rn->rn_key, rn->rn_mask, rnh);
cred = ((struct netcred *)rn)->netc_anon;
if (cred != NULL)
crfree(cred);
free(rn, M_NETADDR);
return (0);
}
/*
* Free the net address hash lists that are hanging off the mount points.
*/
static void
vfs_free_addrlist(struct netexport *nep)
{
int i;
struct radix_node_head *rnh;
struct ucred *cred;
for (i = 0; i <= AF_MAX; i++) {
if ((rnh = nep->ne_rtable[i])) {
RADIX_NODE_HEAD_LOCK(rnh);
(*rnh->rnh_walktree) (rnh, vfs_free_netcred, rnh);
RADIX_NODE_HEAD_UNLOCK(rnh);
RADIX_NODE_HEAD_DESTROY(rnh);
free(rnh, M_RTABLE);
nep->ne_rtable[i] = NULL; /* not SMP safe XXX */
}
}
cred = nep->ne_defexported.netc_anon;
if (cred != NULL)
crfree(cred);
}
/*
* High level function to manipulate export options on a mount point
* and the passed in netexport.
* Struct export_args *argp is the variable used to twiddle options,
* the structure is described in sys/mount.h
*/
int
vfs_export(struct mount *mp, struct export_args *argp)
{
struct netexport *nep;
int error;
if (argp->ex_numsecflavors < 0
|| argp->ex_numsecflavors >= MAXSECFLAVORS)
return (EINVAL);
error = 0;
lockmgr(&mp->mnt_explock, LK_EXCLUSIVE, NULL);
nep = mp->mnt_export;
if (argp->ex_flags & MNT_DELEXPORT) {
if (nep == NULL) {
error = ENOENT;
goto out;
}
if (mp->mnt_flag & MNT_EXPUBLIC) {
vfs_setpublicfs(NULL, NULL, NULL);
MNT_ILOCK(mp);
mp->mnt_flag &= ~MNT_EXPUBLIC;
MNT_IUNLOCK(mp);
}
vfs_free_addrlist(nep);
mp->mnt_export = NULL;
free(nep, M_MOUNT);
nep = NULL;
MNT_ILOCK(mp);
mp->mnt_flag &= ~(MNT_EXPORTED | MNT_DEFEXPORTED);
MNT_IUNLOCK(mp);
}
if (argp->ex_flags & MNT_EXPORTED) {
if (nep == NULL) {
nep = malloc(sizeof(struct netexport), M_MOUNT, M_WAITOK | M_ZERO);
mp->mnt_export = nep;
}
if (argp->ex_flags & MNT_EXPUBLIC) {
if ((error = vfs_setpublicfs(mp, nep, argp)) != 0)
goto out;
MNT_ILOCK(mp);
mp->mnt_flag |= MNT_EXPUBLIC;
MNT_IUNLOCK(mp);
}
if ((error = vfs_hang_addrlist(mp, nep, argp)))
goto out;
MNT_ILOCK(mp);
mp->mnt_flag |= MNT_EXPORTED;
MNT_IUNLOCK(mp);
}
out:
lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
/*
* Once we have executed the vfs_export() command, we do
* not want to keep the "export" option around in the
* options list, since that will cause subsequent MNT_UPDATE
* calls to fail. The export information is saved in
* mp->mnt_export, so we can safely delete the "export" mount option
* here.
*/
vfs_deleteopt(mp->mnt_optnew, "export");
vfs_deleteopt(mp->mnt_opt, "export");
return (error);
}
/*
* Set the publicly exported filesystem (WebNFS). Currently, only
* one public filesystem is possible in the spec (RFC 2054 and 2055)
*/
int
vfs_setpublicfs(struct mount *mp, struct netexport *nep,
struct export_args *argp)
{
int error;
struct vnode *rvp;
char *cp;
/*
* mp == NULL -> invalidate the current info, the FS is
* no longer exported. May be called from either vfs_export
* or unmount, so check if it hasn't already been done.
*/
if (mp == NULL) {
if (nfs_pub.np_valid) {
nfs_pub.np_valid = 0;
if (nfs_pub.np_index != NULL) {
free(nfs_pub.np_index, M_TEMP);
nfs_pub.np_index = NULL;
}
}
return (0);
}
/*
* Only one allowed at a time.
*/
if (nfs_pub.np_valid != 0 && mp != nfs_pub.np_mount)
return (EBUSY);
/*
* Get real filehandle for root of exported FS.
*/
bzero(&nfs_pub.np_handle, sizeof(nfs_pub.np_handle));
nfs_pub.np_handle.fh_fsid = mp->mnt_stat.f_fsid;
if ((error = VFS_ROOT(mp, LK_EXCLUSIVE, &rvp)))
return (error);
if ((error = VOP_VPTOFH(rvp, &nfs_pub.np_handle.fh_fid)))
return (error);
vput(rvp);
/*
* If an indexfile was specified, pull it in.
*/
if (argp->ex_indexfile != NULL) {
if (nfs_pub.np_index != NULL)
nfs_pub.np_index = malloc(MAXNAMLEN + 1, M_TEMP,
M_WAITOK);
error = copyinstr(argp->ex_indexfile, nfs_pub.np_index,
MAXNAMLEN, (size_t *)0);
if (!error) {
/*
* Check for illegal filenames.
*/
for (cp = nfs_pub.np_index; *cp; cp++) {
if (*cp == '/') {
error = EINVAL;
break;
}
}
}
if (error) {
free(nfs_pub.np_index, M_TEMP);
nfs_pub.np_index = NULL;
return (error);
}
}
nfs_pub.np_mount = mp;
nfs_pub.np_valid = 1;
return (0);
}
/*
* Used by the filesystems to determine if a given network address
* (passed in 'nam') is present in their exports list, returns a pointer
* to struct netcred so that the filesystem can examine it for
* access rights (read/write/etc).
*/
static struct netcred *
vfs_export_lookup(struct mount *mp, struct sockaddr *nam)
{
struct netexport *nep;
register struct netcred *np;
register struct radix_node_head *rnh;
struct sockaddr *saddr;
nep = mp->mnt_export;
if (nep == NULL)
return (NULL);
np = NULL;
if (mp->mnt_flag & MNT_EXPORTED) {
/*
* Lookup in the export list first.
*/
if (nam != NULL) {
saddr = nam;
rnh = nep->ne_rtable[saddr->sa_family];
if (rnh != NULL) {
RADIX_NODE_HEAD_RLOCK(rnh);
np = (struct netcred *)
(*rnh->rnh_matchaddr)(saddr, rnh);
RADIX_NODE_HEAD_RUNLOCK(rnh);
if (np && np->netc_rnodes->rn_flags & RNF_ROOT)
np = NULL;
}
}
/*
* If no address match, use the default if it exists.
*/
if (np == NULL && mp->mnt_flag & MNT_DEFEXPORTED)
np = &nep->ne_defexported;
}
return (np);
}
/*
* XXX: This comment comes from the deprecated ufs_check_export()
* XXX: and may not entirely apply, but lacking something better:
* This is the generic part of fhtovp called after the underlying
* filesystem has validated the file handle.
*
* Verify that a host should have access to a filesystem.
*/
int
vfs_stdcheckexp(struct mount *mp, struct sockaddr *nam, int *extflagsp,
struct ucred **credanonp, int *numsecflavors, int **secflavors)
{
struct netcred *np;
lockmgr(&mp->mnt_explock, LK_SHARED, NULL);
np = vfs_export_lookup(mp, nam);
if (np == NULL) {
lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
*credanonp = NULL;
return (EACCES);
}
*extflagsp = np->netc_exflags;
if ((*credanonp = np->netc_anon) != NULL)
crhold(*credanonp);
if (numsecflavors)
*numsecflavors = np->netc_numsecflavors;
if (secflavors)
*secflavors = np->netc_secflavors;
lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
return (0);
}