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linux/fs/nfsd/vfs.c
Christian Brauner 4609e1f18e
fs: port ->permission() to pass mnt_idmap 
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:28 +01:00

2393 lines
59 KiB
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// SPDX-License-Identifier: GPL-2.0
/*
* File operations used by nfsd. Some of these have been ripped from
* other parts of the kernel because they weren't exported, others
* are partial duplicates with added or changed functionality.
*
* Note that several functions dget() the dentry upon which they want
* to act, most notably those that create directory entries. Response
* dentry's are dput()'d if necessary in the release callback.
* So if you notice code paths that apparently fail to dput() the
* dentry, don't worry--they have been taken care of.
*
* Copyright (C) 1995-1999 Olaf Kirch <okir@monad.swb.de>
* Zerocpy NFS support (C) 2002 Hirokazu Takahashi <taka@valinux.co.jp>
*/
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/splice.h>
#include <linux/falloc.h>
#include <linux/fcntl.h>
#include <linux/namei.h>
#include <linux/delay.h>
#include <linux/fsnotify.h>
#include <linux/posix_acl_xattr.h>
#include <linux/xattr.h>
#include <linux/jhash.h>
#include <linux/ima.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/exportfs.h>
#include <linux/writeback.h>
#include <linux/security.h>
#include "xdr3.h"
#ifdef CONFIG_NFSD_V4
#include "../internal.h"
#include "acl.h"
#include "idmap.h"
#include "xdr4.h"
#endif /* CONFIG_NFSD_V4 */
#include "nfsd.h"
#include "vfs.h"
#include "filecache.h"
#include "trace.h"
#define NFSDDBG_FACILITY NFSDDBG_FILEOP
/**
* nfserrno - Map Linux errnos to NFS errnos
* @errno: POSIX(-ish) error code to be mapped
*
* Returns the appropriate (net-endian) nfserr_* (or nfs_ok if errno is 0). If
* it's an error we don't expect, log it once and return nfserr_io.
*/
__be32
nfserrno (int errno)
{
static struct {
__be32 nfserr;
int syserr;
} nfs_errtbl[] = {
{ nfs_ok, 0 },
{ nfserr_perm, -EPERM },
{ nfserr_noent, -ENOENT },
{ nfserr_io, -EIO },
{ nfserr_nxio, -ENXIO },
{ nfserr_fbig, -E2BIG },
{ nfserr_stale, -EBADF },
{ nfserr_acces, -EACCES },
{ nfserr_exist, -EEXIST },
{ nfserr_xdev, -EXDEV },
{ nfserr_mlink, -EMLINK },
{ nfserr_nodev, -ENODEV },
{ nfserr_notdir, -ENOTDIR },
{ nfserr_isdir, -EISDIR },
{ nfserr_inval, -EINVAL },
{ nfserr_fbig, -EFBIG },
{ nfserr_nospc, -ENOSPC },
{ nfserr_rofs, -EROFS },
{ nfserr_mlink, -EMLINK },
{ nfserr_nametoolong, -ENAMETOOLONG },
{ nfserr_notempty, -ENOTEMPTY },
{ nfserr_dquot, -EDQUOT },
{ nfserr_stale, -ESTALE },
{ nfserr_jukebox, -ETIMEDOUT },
{ nfserr_jukebox, -ERESTARTSYS },
{ nfserr_jukebox, -EAGAIN },
{ nfserr_jukebox, -EWOULDBLOCK },
{ nfserr_jukebox, -ENOMEM },
{ nfserr_io, -ETXTBSY },
{ nfserr_notsupp, -EOPNOTSUPP },
{ nfserr_toosmall, -ETOOSMALL },
{ nfserr_serverfault, -ESERVERFAULT },
{ nfserr_serverfault, -ENFILE },
{ nfserr_io, -EREMOTEIO },
{ nfserr_stale, -EOPENSTALE },
{ nfserr_io, -EUCLEAN },
{ nfserr_perm, -ENOKEY },
{ nfserr_no_grace, -ENOGRACE},
};
int i;
for (i = 0; i < ARRAY_SIZE(nfs_errtbl); i++) {
if (nfs_errtbl[i].syserr == errno)
return nfs_errtbl[i].nfserr;
}
WARN_ONCE(1, "nfsd: non-standard errno: %d\n", errno);
return nfserr_io;
}
/*
* Called from nfsd_lookup and encode_dirent. Check if we have crossed
* a mount point.
* Returns -EAGAIN or -ETIMEDOUT leaving *dpp and *expp unchanged,
* or nfs_ok having possibly changed *dpp and *expp
*/
int
nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp,
struct svc_export **expp)
{
struct svc_export *exp = *expp, *exp2 = NULL;
struct dentry *dentry = *dpp;
struct path path = {.mnt = mntget(exp->ex_path.mnt),
.dentry = dget(dentry)};
int err = 0;
err = follow_down(&path);
if (err < 0)
goto out;
if (path.mnt == exp->ex_path.mnt && path.dentry == dentry &&
nfsd_mountpoint(dentry, exp) == 2) {
/* This is only a mountpoint in some other namespace */
path_put(&path);
goto out;
}
exp2 = rqst_exp_get_by_name(rqstp, &path);
if (IS_ERR(exp2)) {
err = PTR_ERR(exp2);
/*
* We normally allow NFS clients to continue
* "underneath" a mountpoint that is not exported.
* The exception is V4ROOT, where no traversal is ever
* allowed without an explicit export of the new
* directory.
*/
if (err == -ENOENT && !(exp->ex_flags & NFSEXP_V4ROOT))
err = 0;
path_put(&path);
goto out;
}
if (nfsd_v4client(rqstp) ||
(exp->ex_flags & NFSEXP_CROSSMOUNT) || EX_NOHIDE(exp2)) {
/* successfully crossed mount point */
/*
* This is subtle: path.dentry is *not* on path.mnt
* at this point. The only reason we are safe is that
* original mnt is pinned down by exp, so we should
* put path *before* putting exp
*/
*dpp = path.dentry;
path.dentry = dentry;
*expp = exp2;
exp2 = exp;
}
path_put(&path);
exp_put(exp2);
out:
return err;
}
static void follow_to_parent(struct path *path)
{
struct dentry *dp;
while (path->dentry == path->mnt->mnt_root && follow_up(path))
;
dp = dget_parent(path->dentry);
dput(path->dentry);
path->dentry = dp;
}
static int nfsd_lookup_parent(struct svc_rqst *rqstp, struct dentry *dparent, struct svc_export **exp, struct dentry **dentryp)
{
struct svc_export *exp2;
struct path path = {.mnt = mntget((*exp)->ex_path.mnt),
.dentry = dget(dparent)};
follow_to_parent(&path);
exp2 = rqst_exp_parent(rqstp, &path);
if (PTR_ERR(exp2) == -ENOENT) {
*dentryp = dget(dparent);
} else if (IS_ERR(exp2)) {
path_put(&path);
return PTR_ERR(exp2);
} else {
*dentryp = dget(path.dentry);
exp_put(*exp);
*exp = exp2;
}
path_put(&path);
return 0;
}
/*
* For nfsd purposes, we treat V4ROOT exports as though there was an
* export at *every* directory.
* We return:
* '1' if this dentry *must* be an export point,
* '2' if it might be, if there is really a mount here, and
* '0' if there is no chance of an export point here.
*/
int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
{
if (!d_inode(dentry))
return 0;
if (exp->ex_flags & NFSEXP_V4ROOT)
return 1;
if (nfsd4_is_junction(dentry))
return 1;
if (d_mountpoint(dentry))
/*
* Might only be a mountpoint in a different namespace,
* but we need to check.
*/
return 2;
return 0;
}
__be32
nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
const char *name, unsigned int len,
struct svc_export **exp_ret, struct dentry **dentry_ret)
{
struct svc_export *exp;
struct dentry *dparent;
struct dentry *dentry;
int host_err;
dprintk("nfsd: nfsd_lookup(fh %s, %.*s)\n", SVCFH_fmt(fhp), len,name);
dparent = fhp->fh_dentry;
exp = exp_get(fhp->fh_export);
/* Lookup the name, but don't follow links */
if (isdotent(name, len)) {
if (len==1)
dentry = dget(dparent);
else if (dparent != exp->ex_path.dentry)
dentry = dget_parent(dparent);
else if (!EX_NOHIDE(exp) && !nfsd_v4client(rqstp))
dentry = dget(dparent); /* .. == . just like at / */
else {
/* checking mountpoint crossing is very different when stepping up */
host_err = nfsd_lookup_parent(rqstp, dparent, &exp, &dentry);
if (host_err)
goto out_nfserr;
}
} else {
dentry = lookup_one_len_unlocked(name, dparent, len);
host_err = PTR_ERR(dentry);
if (IS_ERR(dentry))
goto out_nfserr;
if (nfsd_mountpoint(dentry, exp)) {
host_err = nfsd_cross_mnt(rqstp, &dentry, &exp);
if (host_err) {
dput(dentry);
goto out_nfserr;
}
}
}
*dentry_ret = dentry;
*exp_ret = exp;
return 0;
out_nfserr:
exp_put(exp);
return nfserrno(host_err);
}
/**
* nfsd_lookup - look up a single path component for nfsd
*
* @rqstp: the request context
* @fhp: the file handle of the directory
* @name: the component name, or %NULL to look up parent
* @len: length of name to examine
* @resfh: pointer to pre-initialised filehandle to hold result.
*
* Look up one component of a pathname.
* N.B. After this call _both_ fhp and resfh need an fh_put
*
* If the lookup would cross a mountpoint, and the mounted filesystem
* is exported to the client with NFSEXP_NOHIDE, then the lookup is
* accepted as it stands and the mounted directory is
* returned. Otherwise the covered directory is returned.
* NOTE: this mountpoint crossing is not supported properly by all
* clients and is explicitly disallowed for NFSv3
*
*/
__be32
nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
unsigned int len, struct svc_fh *resfh)
{
struct svc_export *exp;
struct dentry *dentry;
__be32 err;
err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
if (err)
return err;
err = nfsd_lookup_dentry(rqstp, fhp, name, len, &exp, &dentry);
if (err)
return err;
err = check_nfsd_access(exp, rqstp);
if (err)
goto out;
/*
* Note: we compose the file handle now, but as the
* dentry may be negative, it may need to be updated.
*/
err = fh_compose(resfh, exp, dentry, fhp);
if (!err && d_really_is_negative(dentry))
err = nfserr_noent;
out:
dput(dentry);
exp_put(exp);
return err;
}
/*
* Commit metadata changes to stable storage.
*/
static int
commit_inode_metadata(struct inode *inode)
{
const struct export_operations *export_ops = inode->i_sb->s_export_op;
if (export_ops->commit_metadata)
return export_ops->commit_metadata(inode);
return sync_inode_metadata(inode, 1);
}
static int
commit_metadata(struct svc_fh *fhp)
{
struct inode *inode = d_inode(fhp->fh_dentry);
if (!EX_ISSYNC(fhp->fh_export))
return 0;
return commit_inode_metadata(inode);
}
/*
* Go over the attributes and take care of the small differences between
* NFS semantics and what Linux expects.
*/
static void
nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap)
{
/* Ignore mode updates on symlinks */
if (S_ISLNK(inode->i_mode))
iap->ia_valid &= ~ATTR_MODE;
/* sanitize the mode change */
if (iap->ia_valid & ATTR_MODE) {
iap->ia_mode &= S_IALLUGO;
iap->ia_mode |= (inode->i_mode & ~S_IALLUGO);
}
/* Revoke setuid/setgid on chown */
if (!S_ISDIR(inode->i_mode) &&
((iap->ia_valid & ATTR_UID) || (iap->ia_valid & ATTR_GID))) {
iap->ia_valid |= ATTR_KILL_PRIV;
if (iap->ia_valid & ATTR_MODE) {
/* we're setting mode too, just clear the s*id bits */
iap->ia_mode &= ~S_ISUID;
if (iap->ia_mode & S_IXGRP)
iap->ia_mode &= ~S_ISGID;
} else {
/* set ATTR_KILL_* bits and let VFS handle it */
iap->ia_valid |= (ATTR_KILL_SUID | ATTR_KILL_SGID);
}
}
}
static __be32
nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
struct iattr *iap)
{
struct inode *inode = d_inode(fhp->fh_dentry);
if (iap->ia_size < inode->i_size) {
__be32 err;
err = nfsd_permission(rqstp, fhp->fh_export, fhp->fh_dentry,
NFSD_MAY_TRUNC | NFSD_MAY_OWNER_OVERRIDE);
if (err)
return err;
}
return nfserrno(get_write_access(inode));
}
static int __nfsd_setattr(struct dentry *dentry, struct iattr *iap)
{
int host_err;
if (iap->ia_valid & ATTR_SIZE) {
/*
* RFC5661, Section 18.30.4:
* Changing the size of a file with SETATTR indirectly
* changes the time_modify and change attributes.
*
* (and similar for the older RFCs)
*/
struct iattr size_attr = {
.ia_valid = ATTR_SIZE | ATTR_CTIME | ATTR_MTIME,
.ia_size = iap->ia_size,
};
if (iap->ia_size < 0)
return -EFBIG;
host_err = notify_change(&nop_mnt_idmap, dentry, &size_attr, NULL);
if (host_err)
return host_err;
iap->ia_valid &= ~ATTR_SIZE;
/*
* Avoid the additional setattr call below if the only other
* attribute that the client sends is the mtime, as we update
* it as part of the size change above.
*/
if ((iap->ia_valid & ~ATTR_MTIME) == 0)
return 0;
}
if (!iap->ia_valid)
return 0;
iap->ia_valid |= ATTR_CTIME;
return notify_change(&nop_mnt_idmap, dentry, iap, NULL);
}
/**
* nfsd_setattr - Set various file attributes.
* @rqstp: controlling RPC transaction
* @fhp: filehandle of target
* @attr: attributes to set
* @check_guard: set to 1 if guardtime is a valid timestamp
* @guardtime: do not act if ctime.tv_sec does not match this timestamp
*
* This call may adjust the contents of @attr (in particular, this
* call may change the bits in the na_iattr.ia_valid field).
*
* Returns nfs_ok on success, otherwise an NFS status code is
* returned. Caller must release @fhp by calling fh_put in either
* case.
*/
__be32
nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
struct nfsd_attrs *attr,
int check_guard, time64_t guardtime)
{
struct dentry *dentry;
struct inode *inode;
struct iattr *iap = attr->na_iattr;
int accmode = NFSD_MAY_SATTR;
umode_t ftype = 0;
__be32 err;
int host_err;
bool get_write_count;
bool size_change = (iap->ia_valid & ATTR_SIZE);
int retries;
if (iap->ia_valid & ATTR_SIZE) {
accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
ftype = S_IFREG;
}
/*
* If utimes(2) and friends are called with times not NULL, we should
* not set NFSD_MAY_WRITE bit. Otherwise fh_verify->nfsd_permission
* will return EACCES, when the caller's effective UID does not match
* the owner of the file, and the caller is not privileged. In this
* situation, we should return EPERM(notify_change will return this).
*/
if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME)) {
accmode |= NFSD_MAY_OWNER_OVERRIDE;
if (!(iap->ia_valid & (ATTR_ATIME_SET | ATTR_MTIME_SET)))
accmode |= NFSD_MAY_WRITE;
}
/* Callers that do fh_verify should do the fh_want_write: */
get_write_count = !fhp->fh_dentry;
/* Get inode */
err = fh_verify(rqstp, fhp, ftype, accmode);
if (err)
return err;
if (get_write_count) {
host_err = fh_want_write(fhp);
if (host_err)
goto out;
}
dentry = fhp->fh_dentry;
inode = d_inode(dentry);
nfsd_sanitize_attrs(inode, iap);
if (check_guard && guardtime != inode->i_ctime.tv_sec)
return nfserr_notsync;
/*
* The size case is special, it changes the file in addition to the
* attributes, and file systems don't expect it to be mixed with
* "random" attribute changes. We thus split out the size change
* into a separate call to ->setattr, and do the rest as a separate
* setattr call.
*/
if (size_change) {
err = nfsd_get_write_access(rqstp, fhp, iap);
if (err)
return err;
}
inode_lock(inode);
for (retries = 1;;) {
host_err = __nfsd_setattr(dentry, iap);
if (host_err != -EAGAIN || !retries--)
break;
if (!nfsd_wait_for_delegreturn(rqstp, inode))
break;
}
if (attr->na_seclabel && attr->na_seclabel->len)
attr->na_labelerr = security_inode_setsecctx(dentry,
attr->na_seclabel->data, attr->na_seclabel->len);
if (IS_ENABLED(CONFIG_FS_POSIX_ACL) && attr->na_pacl)
attr->na_aclerr = set_posix_acl(&nop_mnt_idmap,
dentry, ACL_TYPE_ACCESS,
attr->na_pacl);
if (IS_ENABLED(CONFIG_FS_POSIX_ACL) &&
!attr->na_aclerr && attr->na_dpacl && S_ISDIR(inode->i_mode))
attr->na_aclerr = set_posix_acl(&nop_mnt_idmap,
dentry, ACL_TYPE_DEFAULT,
attr->na_dpacl);
inode_unlock(inode);
if (size_change)
put_write_access(inode);
out:
if (!host_err)
host_err = commit_metadata(fhp);
return nfserrno(host_err);
}
#if defined(CONFIG_NFSD_V4)
/*
* NFS junction information is stored in an extended attribute.
*/
#define NFSD_JUNCTION_XATTR_NAME XATTR_TRUSTED_PREFIX "junction.nfs"
/**
* nfsd4_is_junction - Test if an object could be an NFS junction
*
* @dentry: object to test
*
* Returns 1 if "dentry" appears to contain NFS junction information.
* Otherwise 0 is returned.
*/
int nfsd4_is_junction(struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
if (inode == NULL)
return 0;
if (inode->i_mode & S_IXUGO)
return 0;
if (!(inode->i_mode & S_ISVTX))
return 0;
if (vfs_getxattr(&nop_mnt_idmap, dentry, NFSD_JUNCTION_XATTR_NAME,
NULL, 0) <= 0)
return 0;
return 1;
}
static struct nfsd4_compound_state *nfsd4_get_cstate(struct svc_rqst *rqstp)
{
return &((struct nfsd4_compoundres *)rqstp->rq_resp)->cstate;
}
__be32 nfsd4_clone_file_range(struct svc_rqst *rqstp,
struct nfsd_file *nf_src, u64 src_pos,
struct nfsd_file *nf_dst, u64 dst_pos,
u64 count, bool sync)
{
struct file *src = nf_src->nf_file;
struct file *dst = nf_dst->nf_file;
errseq_t since;
loff_t cloned;
__be32 ret = 0;
since = READ_ONCE(dst->f_wb_err);
cloned = vfs_clone_file_range(src, src_pos, dst, dst_pos, count, 0);
if (cloned < 0) {
ret = nfserrno(cloned);
goto out_err;
}
if (count && cloned != count) {
ret = nfserrno(-EINVAL);
goto out_err;
}
if (sync) {
loff_t dst_end = count ? dst_pos + count - 1 : LLONG_MAX;
int status = vfs_fsync_range(dst, dst_pos, dst_end, 0);
if (!status)
status = filemap_check_wb_err(dst->f_mapping, since);
if (!status)
status = commit_inode_metadata(file_inode(src));
if (status < 0) {
struct nfsd_net *nn = net_generic(nf_dst->nf_net,
nfsd_net_id);
trace_nfsd_clone_file_range_err(rqstp,
&nfsd4_get_cstate(rqstp)->save_fh,
src_pos,
&nfsd4_get_cstate(rqstp)->current_fh,
dst_pos,
count, status);
nfsd_reset_write_verifier(nn);
trace_nfsd_writeverf_reset(nn, rqstp, status);
ret = nfserrno(status);
}
}
out_err:
return ret;
}
ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
u64 dst_pos, u64 count)
{
ssize_t ret;
/*
* Limit copy to 4MB to prevent indefinitely blocking an nfsd
* thread and client rpc slot. The choice of 4MB is somewhat
* arbitrary. We might instead base this on r/wsize, or make it
* tunable, or use a time instead of a byte limit, or implement
* asynchronous copy. In theory a client could also recognize a
* limit like this and pipeline multiple COPY requests.
*/
count = min_t(u64, count, 1 << 22);
ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
if (ret == -EOPNOTSUPP || ret == -EXDEV)
ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count,
COPY_FILE_SPLICE);
return ret;
}
__be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp,
struct file *file, loff_t offset, loff_t len,
int flags)
{
int error;
if (!S_ISREG(file_inode(file)->i_mode))
return nfserr_inval;
error = vfs_fallocate(file, flags, offset, len);
if (!error)
error = commit_metadata(fhp);
return nfserrno(error);
}
#endif /* defined(CONFIG_NFSD_V4) */
/*
* Check server access rights to a file system object
*/
struct accessmap {
u32 access;
int how;
};
static struct accessmap nfs3_regaccess[] = {
{ NFS3_ACCESS_READ, NFSD_MAY_READ },
{ NFS3_ACCESS_EXECUTE, NFSD_MAY_EXEC },
{ NFS3_ACCESS_MODIFY, NFSD_MAY_WRITE|NFSD_MAY_TRUNC },
{ NFS3_ACCESS_EXTEND, NFSD_MAY_WRITE },
#ifdef CONFIG_NFSD_V4
{ NFS4_ACCESS_XAREAD, NFSD_MAY_READ },
{ NFS4_ACCESS_XAWRITE, NFSD_MAY_WRITE },
{ NFS4_ACCESS_XALIST, NFSD_MAY_READ },
#endif
{ 0, 0 }
};
static struct accessmap nfs3_diraccess[] = {
{ NFS3_ACCESS_READ, NFSD_MAY_READ },
{ NFS3_ACCESS_LOOKUP, NFSD_MAY_EXEC },
{ NFS3_ACCESS_MODIFY, NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC},
{ NFS3_ACCESS_EXTEND, NFSD_MAY_EXEC|NFSD_MAY_WRITE },
{ NFS3_ACCESS_DELETE, NFSD_MAY_REMOVE },
#ifdef CONFIG_NFSD_V4
{ NFS4_ACCESS_XAREAD, NFSD_MAY_READ },
{ NFS4_ACCESS_XAWRITE, NFSD_MAY_WRITE },
{ NFS4_ACCESS_XALIST, NFSD_MAY_READ },
#endif
{ 0, 0 }
};
static struct accessmap nfs3_anyaccess[] = {
/* Some clients - Solaris 2.6 at least, make an access call
* to the server to check for access for things like /dev/null
* (which really, the server doesn't care about). So
* We provide simple access checking for them, looking
* mainly at mode bits, and we make sure to ignore read-only
* filesystem checks
*/
{ NFS3_ACCESS_READ, NFSD_MAY_READ },
{ NFS3_ACCESS_EXECUTE, NFSD_MAY_EXEC },
{ NFS3_ACCESS_MODIFY, NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS },
{ NFS3_ACCESS_EXTEND, NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS },
{ 0, 0 }
};
__be32
nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access, u32 *supported)
{
struct accessmap *map;
struct svc_export *export;
struct dentry *dentry;
u32 query, result = 0, sresult = 0;
__be32 error;
error = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP);
if (error)
goto out;
export = fhp->fh_export;
dentry = fhp->fh_dentry;
if (d_is_reg(dentry))
map = nfs3_regaccess;
else if (d_is_dir(dentry))
map = nfs3_diraccess;
else
map = nfs3_anyaccess;
query = *access;
for (; map->access; map++) {
if (map->access & query) {
__be32 err2;
sresult |= map->access;
err2 = nfsd_permission(rqstp, export, dentry, map->how);
switch (err2) {
case nfs_ok:
result |= map->access;
break;
/* the following error codes just mean the access was not allowed,
* rather than an error occurred */
case nfserr_rofs:
case nfserr_acces:
case nfserr_perm:
/* simply don't "or" in the access bit. */
break;
default:
error = err2;
goto out;
}
}
}
*access = result;
if (supported)
*supported = sresult;
out:
return error;
}
int nfsd_open_break_lease(struct inode *inode, int access)
{
unsigned int mode;
if (access & NFSD_MAY_NOT_BREAK_LEASE)
return 0;
mode = (access & NFSD_MAY_WRITE) ? O_WRONLY : O_RDONLY;
return break_lease(inode, mode | O_NONBLOCK);
}
/*
* Open an existing file or directory.
* The may_flags argument indicates the type of open (read/write/lock)
* and additional flags.
* N.B. After this call fhp needs an fh_put
*/
static __be32
__nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
int may_flags, struct file **filp)
{
struct path path;
struct inode *inode;
struct file *file;
int flags = O_RDONLY|O_LARGEFILE;
__be32 err;
int host_err = 0;
path.mnt = fhp->fh_export->ex_path.mnt;
path.dentry = fhp->fh_dentry;
inode = d_inode(path.dentry);
err = nfserr_perm;
if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
goto out;
if (!inode->i_fop)
goto out;
host_err = nfsd_open_break_lease(inode, may_flags);
if (host_err) /* NOMEM or WOULDBLOCK */
goto out_nfserr;
if (may_flags & NFSD_MAY_WRITE) {
if (may_flags & NFSD_MAY_READ)
flags = O_RDWR|O_LARGEFILE;
else
flags = O_WRONLY|O_LARGEFILE;
}
file = dentry_open(&path, flags, current_cred());
if (IS_ERR(file)) {
host_err = PTR_ERR(file);
goto out_nfserr;
}
host_err = ima_file_check(file, may_flags);
if (host_err) {
fput(file);
goto out_nfserr;
}
if (may_flags & NFSD_MAY_64BIT_COOKIE)
file->f_mode |= FMODE_64BITHASH;
else
file->f_mode |= FMODE_32BITHASH;
*filp = file;
out_nfserr:
err = nfserrno(host_err);
out:
return err;
}
__be32
nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
int may_flags, struct file **filp)
{
__be32 err;
bool retried = false;
validate_process_creds();
/*
* If we get here, then the client has already done an "open",
* and (hopefully) checked permission - so allow OWNER_OVERRIDE
* in case a chmod has now revoked permission.
*
* Arguably we should also allow the owner override for
* directories, but we never have and it doesn't seem to have
* caused anyone a problem. If we were to change this, note
* also that our filldir callbacks would need a variant of
* lookup_one_len that doesn't check permissions.
*/
if (type == S_IFREG)
may_flags |= NFSD_MAY_OWNER_OVERRIDE;
retry:
err = fh_verify(rqstp, fhp, type, may_flags);
if (!err) {
err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
if (err == nfserr_stale && !retried) {
retried = true;
fh_put(fhp);
goto retry;
}
}
validate_process_creds();
return err;
}
/**
* nfsd_open_verified - Open a regular file for the filecache
* @rqstp: RPC request
* @fhp: NFS filehandle of the file to open
* @may_flags: internal permission flags
* @filp: OUT: open "struct file *"
*
* Returns an nfsstat value in network byte order.
*/
__be32
nfsd_open_verified(struct svc_rqst *rqstp, struct svc_fh *fhp, int may_flags,
struct file **filp)
{
__be32 err;
validate_process_creds();
err = __nfsd_open(rqstp, fhp, S_IFREG, may_flags, filp);
validate_process_creds();
return err;
}
/*
* Grab and keep cached pages associated with a file in the svc_rqst
* so that they can be passed to the network sendmsg/sendpage routines
* directly. They will be released after the sending has completed.
*/
static int
nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
struct splice_desc *sd)
{
struct svc_rqst *rqstp = sd->u.data;
struct page *page = buf->page; // may be a compound one
unsigned offset = buf->offset;
struct page *last_page;
last_page = page + (offset + sd->len - 1) / PAGE_SIZE;
for (page += offset / PAGE_SIZE; page <= last_page; page++)
svc_rqst_replace_page(rqstp, page);
if (rqstp->rq_res.page_len == 0) // first call
rqstp->rq_res.page_base = offset % PAGE_SIZE;
rqstp->rq_res.page_len += sd->len;
return sd->len;
}
static int nfsd_direct_splice_actor(struct pipe_inode_info *pipe,
struct splice_desc *sd)
{
return __splice_from_pipe(pipe, sd, nfsd_splice_actor);
}
static u32 nfsd_eof_on_read(struct file *file, loff_t offset, ssize_t len,
size_t expected)
{
if (expected != 0 && len == 0)
return 1;
if (offset+len >= i_size_read(file_inode(file)))
return 1;
return 0;
}
static __be32 nfsd_finish_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
struct file *file, loff_t offset,
unsigned long *count, u32 *eof, ssize_t host_err)
{
if (host_err >= 0) {
nfsd_stats_io_read_add(fhp->fh_export, host_err);
*eof = nfsd_eof_on_read(file, offset, host_err, *count);
*count = host_err;
fsnotify_access(file);
trace_nfsd_read_io_done(rqstp, fhp, offset, *count);
return 0;
} else {
trace_nfsd_read_err(rqstp, fhp, offset, host_err);
return nfserrno(host_err);
}
}
__be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
struct file *file, loff_t offset, unsigned long *count,
u32 *eof)
{
struct splice_desc sd = {
.len = 0,
.total_len = *count,
.pos = offset,
.u.data = rqstp,
};
ssize_t host_err;
trace_nfsd_read_splice(rqstp, fhp, offset, *count);
rqstp->rq_next_page = rqstp->rq_respages + 1;
host_err = splice_direct_to_actor(file, &sd, nfsd_direct_splice_actor);
return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
}
__be32 nfsd_readv(struct svc_rqst *rqstp, struct svc_fh *fhp,
struct file *file, loff_t offset,
struct kvec *vec, int vlen, unsigned long *count,
u32 *eof)
{
struct iov_iter iter;
loff_t ppos = offset;
ssize_t host_err;
trace_nfsd_read_vector(rqstp, fhp, offset, *count);
iov_iter_kvec(&iter, ITER_DEST, vec, vlen, *count);
host_err = vfs_iter_read(file, &iter, &ppos, 0);
return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
}
/*
* Gathered writes: If another process is currently writing to the file,
* there's a high chance this is another nfsd (triggered by a bulk write
* from a client's biod). Rather than syncing the file with each write
* request, we sleep for 10 msec.
*
* I don't know if this roughly approximates C. Juszak's idea of
* gathered writes, but it's a nice and simple solution (IMHO), and it
* seems to work:-)
*
* Note: we do this only in the NFSv2 case, since v3 and higher have a
* better tool (separate unstable writes and commits) for solving this
* problem.
*/
static int wait_for_concurrent_writes(struct file *file)
{
struct inode *inode = file_inode(file);
static ino_t last_ino;
static dev_t last_dev;
int err = 0;
if (atomic_read(&inode->i_writecount) > 1
|| (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
dprintk("nfsd: write defer %d\n", task_pid_nr(current));
msleep(10);
dprintk("nfsd: write resume %d\n", task_pid_nr(current));
}
if (inode->i_state & I_DIRTY) {
dprintk("nfsd: write sync %d\n", task_pid_nr(current));
err = vfs_fsync(file, 0);
}
last_ino = inode->i_ino;
last_dev = inode->i_sb->s_dev;
return err;
}
__be32
nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
loff_t offset, struct kvec *vec, int vlen,
unsigned long *cnt, int stable,
__be32 *verf)
{
struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
struct file *file = nf->nf_file;
struct super_block *sb = file_inode(file)->i_sb;
struct svc_export *exp;
struct iov_iter iter;
errseq_t since;
__be32 nfserr;
int host_err;
int use_wgather;
loff_t pos = offset;
unsigned long exp_op_flags = 0;
unsigned int pflags = current->flags;
rwf_t flags = 0;
bool restore_flags = false;
trace_nfsd_write_opened(rqstp, fhp, offset, *cnt);
if (sb->s_export_op)
exp_op_flags = sb->s_export_op->flags;
if (test_bit(RQ_LOCAL, &rqstp->rq_flags) &&
!(exp_op_flags & EXPORT_OP_REMOTE_FS)) {
/*
* We want throttling in balance_dirty_pages()
* and shrink_inactive_list() to only consider
* the backingdev we are writing to, so that nfs to
* localhost doesn't cause nfsd to lock up due to all
* the client's dirty pages or its congested queue.
*/
current->flags |= PF_LOCAL_THROTTLE;
restore_flags = true;
}
exp = fhp->fh_export;
use_wgather = (rqstp->rq_vers == 2) && EX_WGATHER(exp);
if (!EX_ISSYNC(exp))
stable = NFS_UNSTABLE;
if (stable && !use_wgather)
flags |= RWF_SYNC;
iov_iter_kvec(&iter, ITER_SOURCE, vec, vlen, *cnt);
since = READ_ONCE(file->f_wb_err);
if (verf)
nfsd_copy_write_verifier(verf, nn);
host_err = vfs_iter_write(file, &iter, &pos, flags);
if (host_err < 0) {
nfsd_reset_write_verifier(nn);
trace_nfsd_writeverf_reset(nn, rqstp, host_err);
goto out_nfserr;
}
*cnt = host_err;
nfsd_stats_io_write_add(exp, *cnt);
fsnotify_modify(file);
host_err = filemap_check_wb_err(file->f_mapping, since);
if (host_err < 0)
goto out_nfserr;
if (stable && use_wgather) {
host_err = wait_for_concurrent_writes(file);
if (host_err < 0) {
nfsd_reset_write_verifier(nn);
trace_nfsd_writeverf_reset(nn, rqstp, host_err);
}
}
out_nfserr:
if (host_err >= 0) {
trace_nfsd_write_io_done(rqstp, fhp, offset, *cnt);
nfserr = nfs_ok;
} else {
trace_nfsd_write_err(rqstp, fhp, offset, host_err);
nfserr = nfserrno(host_err);
}
if (restore_flags)
current_restore_flags(pflags, PF_LOCAL_THROTTLE);
return nfserr;
}
/*
* Read data from a file. count must contain the requested read count
* on entry. On return, *count contains the number of bytes actually read.
* N.B. After this call fhp needs an fh_put
*/
__be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
loff_t offset, struct kvec *vec, int vlen, unsigned long *count,
u32 *eof)
{
struct nfsd_file *nf;
struct file *file;
__be32 err;
trace_nfsd_read_start(rqstp, fhp, offset, *count);
err = nfsd_file_acquire_gc(rqstp, fhp, NFSD_MAY_READ, &nf);
if (err)
return err;
file = nf->nf_file;
if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &rqstp->rq_flags))
err = nfsd_splice_read(rqstp, fhp, file, offset, count, eof);
else
err = nfsd_readv(rqstp, fhp, file, offset, vec, vlen, count, eof);
nfsd_file_put(nf);
trace_nfsd_read_done(rqstp, fhp, offset, *count);
return err;
}
/*
* Write data to a file.
* The stable flag requests synchronous writes.
* N.B. After this call fhp needs an fh_put
*/
__be32
nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
struct kvec *vec, int vlen, unsigned long *cnt, int stable,
__be32 *verf)
{
struct nfsd_file *nf;
__be32 err;
trace_nfsd_write_start(rqstp, fhp, offset, *cnt);
err = nfsd_file_acquire_gc(rqstp, fhp, NFSD_MAY_WRITE, &nf);
if (err)
goto out;
err = nfsd_vfs_write(rqstp, fhp, nf, offset, vec,
vlen, cnt, stable, verf);
nfsd_file_put(nf);
out:
trace_nfsd_write_done(rqstp, fhp, offset, *cnt);
return err;
}
/**
* nfsd_commit - Commit pending writes to stable storage
* @rqstp: RPC request being processed
* @fhp: NFS filehandle
* @nf: target file
* @offset: raw offset from beginning of file
* @count: raw count of bytes to sync
* @verf: filled in with the server's current write verifier
*
* Note: we guarantee that data that lies within the range specified
* by the 'offset' and 'count' parameters will be synced. The server
* is permitted to sync data that lies outside this range at the
* same time.
*
* Unfortunately we cannot lock the file to make sure we return full WCC
* data to the client, as locking happens lower down in the filesystem.
*
* Return values:
* An nfsstat value in network byte order.
*/
__be32
nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
u64 offset, u32 count, __be32 *verf)
{
__be32 err = nfs_ok;
u64 maxbytes;
loff_t start, end;
struct nfsd_net *nn;
/*
* Convert the client-provided (offset, count) range to a
* (start, end) range. If the client-provided range falls
* outside the maximum file size of the underlying FS,
* clamp the sync range appropriately.
*/
start = 0;
end = LLONG_MAX;
maxbytes = (u64)fhp->fh_dentry->d_sb->s_maxbytes;
if (offset < maxbytes) {
start = offset;
if (count && (offset + count - 1 < maxbytes))
end = offset + count - 1;
}
nn = net_generic(nf->nf_net, nfsd_net_id);
if (EX_ISSYNC(fhp->fh_export)) {
errseq_t since = READ_ONCE(nf->nf_file->f_wb_err);
int err2;
err2 = vfs_fsync_range(nf->nf_file, start, end, 0);
switch (err2) {
case 0:
nfsd_copy_write_verifier(verf, nn);
err2 = filemap_check_wb_err(nf->nf_file->f_mapping,
since);
err = nfserrno(err2);
break;
case -EINVAL:
err = nfserr_notsupp;
break;
default:
nfsd_reset_write_verifier(nn);
trace_nfsd_writeverf_reset(nn, rqstp, err2);
err = nfserrno(err2);
}
} else
nfsd_copy_write_verifier(verf, nn);
return err;
}
/**
* nfsd_create_setattr - Set a created file's attributes
* @rqstp: RPC transaction being executed
* @fhp: NFS filehandle of parent directory
* @resfhp: NFS filehandle of new object
* @attrs: requested attributes of new object
*
* Returns nfs_ok on success, or an nfsstat in network byte order.
*/
__be32
nfsd_create_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
struct svc_fh *resfhp, struct nfsd_attrs *attrs)
{
struct iattr *iap = attrs->na_iattr;
__be32 status;
/*
* Mode has already been set by file creation.
*/
iap->ia_valid &= ~ATTR_MODE;
/*
* Setting uid/gid works only for root. Irix appears to
* send along the gid on create when it tries to implement
* setgid directories via NFS:
*/
if (!uid_eq(current_fsuid(), GLOBAL_ROOT_UID))
iap->ia_valid &= ~(ATTR_UID|ATTR_GID);
/*
* Callers expect new file metadata to be committed even
* if the attributes have not changed.
*/
if (iap->ia_valid)
status = nfsd_setattr(rqstp, resfhp, attrs, 0, (time64_t)0);
else
status = nfserrno(commit_metadata(resfhp));
/*
* Transactional filesystems had a chance to commit changes
* for both parent and child simultaneously making the
* following commit_metadata a noop in many cases.
*/
if (!status)
status = nfserrno(commit_metadata(fhp));
/*
* Update the new filehandle to pick up the new attributes.
*/
if (!status)
status = fh_update(resfhp);
return status;
}
/* HPUX client sometimes creates a file in mode 000, and sets size to 0.
* setting size to 0 may fail for some specific file systems by the permission
* checking which requires WRITE permission but the mode is 000.
* we ignore the resizing(to 0) on the just new created file, since the size is
* 0 after file created.
*
* call this only after vfs_create() is called.
* */
static void
nfsd_check_ignore_resizing(struct iattr *iap)
{
if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
iap->ia_valid &= ~ATTR_SIZE;
}
/* The parent directory should already be locked: */
__be32
nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
struct nfsd_attrs *attrs,
int type, dev_t rdev, struct svc_fh *resfhp)
{
struct dentry *dentry, *dchild;
struct inode *dirp;
struct iattr *iap = attrs->na_iattr;
__be32 err;
int host_err;
dentry = fhp->fh_dentry;
dirp = d_inode(dentry);
dchild = dget(resfhp->fh_dentry);
err = nfsd_permission(rqstp, fhp->fh_export, dentry, NFSD_MAY_CREATE);
if (err)
goto out;
if (!(iap->ia_valid & ATTR_MODE))
iap->ia_mode = 0;
iap->ia_mode = (iap->ia_mode & S_IALLUGO) | type;
if (!IS_POSIXACL(dirp))
iap->ia_mode &= ~current_umask();
err = 0;
switch (type) {
case S_IFREG:
host_err = vfs_create(&nop_mnt_idmap, dirp, dchild,
iap->ia_mode, true);
if (!host_err)
nfsd_check_ignore_resizing(iap);
break;
case S_IFDIR:
host_err = vfs_mkdir(&nop_mnt_idmap, dirp, dchild, iap->ia_mode);
if (!host_err && unlikely(d_unhashed(dchild))) {
struct dentry *d;
d = lookup_one_len(dchild->d_name.name,
dchild->d_parent,
dchild->d_name.len);
if (IS_ERR(d)) {
host_err = PTR_ERR(d);
break;
}
if (unlikely(d_is_negative(d))) {
dput(d);
err = nfserr_serverfault;
goto out;
}
dput(resfhp->fh_dentry);
resfhp->fh_dentry = dget(d);
err = fh_update(resfhp);
dput(dchild);
dchild = d;
if (err)
goto out;
}
break;
case S_IFCHR:
case S_IFBLK:
case S_IFIFO:
case S_IFSOCK:
host_err = vfs_mknod(&nop_mnt_idmap, dirp, dchild,
iap->ia_mode, rdev);
break;
default:
printk(KERN_WARNING "nfsd: bad file type %o in nfsd_create\n",
type);
host_err = -EINVAL;
}
if (host_err < 0)
goto out_nfserr;
err = nfsd_create_setattr(rqstp, fhp, resfhp, attrs);
out:
dput(dchild);
return err;
out_nfserr:
err = nfserrno(host_err);
goto out;
}
/*
* Create a filesystem object (regular, directory, special).
* Note that the parent directory is left locked.
*
* N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
*/
__be32
nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
char *fname, int flen, struct nfsd_attrs *attrs,
int type, dev_t rdev, struct svc_fh *resfhp)
{
struct dentry *dentry, *dchild = NULL;
__be32 err;
int host_err;
if (isdotent(fname, flen))
return nfserr_exist;
err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_NOP);
if (err)
return err;
dentry = fhp->fh_dentry;
host_err = fh_want_write(fhp);
if (host_err)
return nfserrno(host_err);
inode_lock_nested(dentry->d_inode, I_MUTEX_PARENT);
dchild = lookup_one_len(fname, dentry, flen);
host_err = PTR_ERR(dchild);
if (IS_ERR(dchild)) {
err = nfserrno(host_err);
goto out_unlock;
}
err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
/*
* We unconditionally drop our ref to dchild as fh_compose will have
* already grabbed its own ref for it.
*/
dput(dchild);
if (err)
goto out_unlock;
fh_fill_pre_attrs(fhp);
err = nfsd_create_locked(rqstp, fhp, attrs, type, rdev, resfhp);
fh_fill_post_attrs(fhp);
out_unlock:
inode_unlock(dentry->d_inode);
return err;
}
/*
* Read a symlink. On entry, *lenp must contain the maximum path length that
* fits into the buffer. On return, it contains the true length.
* N.B. After this call fhp needs an fh_put
*/
__be32
nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
{
__be32 err;
const char *link;
struct path path;
DEFINE_DELAYED_CALL(done);
int len;
err = fh_verify(rqstp, fhp, S_IFLNK, NFSD_MAY_NOP);
if (unlikely(err))
return err;
path.mnt = fhp->fh_export->ex_path.mnt;
path.dentry = fhp->fh_dentry;
if (unlikely(!d_is_symlink(path.dentry)))
return nfserr_inval;
touch_atime(&path);
link = vfs_get_link(path.dentry, &done);
if (IS_ERR(link))
return nfserrno(PTR_ERR(link));
len = strlen(link);
if (len < *lenp)
*lenp = len;
memcpy(buf, link, *lenp);
do_delayed_call(&done);
return 0;
}
/**
* nfsd_symlink - Create a symlink and look up its inode
* @rqstp: RPC transaction being executed
* @fhp: NFS filehandle of parent directory
* @fname: filename of the new symlink
* @flen: length of @fname
* @path: content of the new symlink (NUL-terminated)
* @attrs: requested attributes of new object
* @resfhp: NFS filehandle of new object
*
* N.B. After this call _both_ fhp and resfhp need an fh_put
*
* Returns nfs_ok on success, or an nfsstat in network byte order.
*/
__be32
nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
char *fname, int flen,
char *path, struct nfsd_attrs *attrs,
struct svc_fh *resfhp)
{
struct dentry *dentry, *dnew;
__be32 err, cerr;
int host_err;
err = nfserr_noent;
if (!flen || path[0] == '\0')
goto out;
err = nfserr_exist;
if (isdotent(fname, flen))
goto out;
err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
if (err)
goto out;
host_err = fh_want_write(fhp);
if (host_err) {
err = nfserrno(host_err);
goto out;
}
dentry = fhp->fh_dentry;
inode_lock_nested(dentry->d_inode, I_MUTEX_PARENT);
dnew = lookup_one_len(fname, dentry, flen);
if (IS_ERR(dnew)) {
err = nfserrno(PTR_ERR(dnew));
inode_unlock(dentry->d_inode);
goto out_drop_write;
}
fh_fill_pre_attrs(fhp);
host_err = vfs_symlink(&nop_mnt_idmap, d_inode(dentry), dnew, path);
err = nfserrno(host_err);
cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
if (!err)
nfsd_create_setattr(rqstp, fhp, resfhp, attrs);
fh_fill_post_attrs(fhp);
inode_unlock(dentry->d_inode);
if (!err)
err = nfserrno(commit_metadata(fhp));
dput(dnew);
if (err==0) err = cerr;
out_drop_write:
fh_drop_write(fhp);
out:
return err;
}
/*
* Create a hardlink
* N.B. After this call _both_ ffhp and tfhp need an fh_put
*/
__be32
nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
char *name, int len, struct svc_fh *tfhp)
{
struct dentry *ddir, *dnew, *dold;
struct inode *dirp;
__be32 err;
int host_err;
err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_CREATE);
if (err)
goto out;
err = fh_verify(rqstp, tfhp, 0, NFSD_MAY_NOP);
if (err)
goto out;
err = nfserr_isdir;
if (d_is_dir(tfhp->fh_dentry))
goto out;
err = nfserr_perm;
if (!len)
goto out;
err = nfserr_exist;
if (isdotent(name, len))
goto out;
host_err = fh_want_write(tfhp);
if (host_err) {
err = nfserrno(host_err);
goto out;
}
ddir = ffhp->fh_dentry;
dirp = d_inode(ddir);
inode_lock_nested(dirp, I_MUTEX_PARENT);
dnew = lookup_one_len(name, ddir, len);
if (IS_ERR(dnew)) {
err = nfserrno(PTR_ERR(dnew));
goto out_unlock;
}
dold = tfhp->fh_dentry;
err = nfserr_noent;
if (d_really_is_negative(dold))
goto out_dput;
fh_fill_pre_attrs(ffhp);
host_err = vfs_link(dold, &nop_mnt_idmap, dirp, dnew, NULL);
fh_fill_post_attrs(ffhp);
inode_unlock(dirp);
if (!host_err) {
err = nfserrno(commit_metadata(ffhp));
if (!err)
err = nfserrno(commit_metadata(tfhp));
} else {
if (host_err == -EXDEV && rqstp->rq_vers == 2)
err = nfserr_acces;
else
err = nfserrno(host_err);
}
dput(dnew);
out_drop_write:
fh_drop_write(tfhp);
out:
return err;
out_dput:
dput(dnew);
out_unlock:
inode_unlock(dirp);
goto out_drop_write;
}
static void
nfsd_close_cached_files(struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
if (inode && S_ISREG(inode->i_mode))
nfsd_file_close_inode_sync(inode);
}
static bool
nfsd_has_cached_files(struct dentry *dentry)
{
bool ret = false;
struct inode *inode = d_inode(dentry);
if (inode && S_ISREG(inode->i_mode))
ret = nfsd_file_is_cached(inode);
return ret;
}
/*
* Rename a file
* N.B. After this call _both_ ffhp and tfhp need an fh_put
*/
__be32
nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
struct svc_fh *tfhp, char *tname, int tlen)
{
struct dentry *fdentry, *tdentry, *odentry, *ndentry, *trap;
struct inode *fdir, *tdir;
__be32 err;
int host_err;
bool close_cached = false;
err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE);
if (err)
goto out;
err = fh_verify(rqstp, tfhp, S_IFDIR, NFSD_MAY_CREATE);
if (err)
goto out;
fdentry = ffhp->fh_dentry;
fdir = d_inode(fdentry);
tdentry = tfhp->fh_dentry;
tdir = d_inode(tdentry);
err = nfserr_perm;
if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
goto out;
retry:
host_err = fh_want_write(ffhp);
if (host_err) {
err = nfserrno(host_err);
goto out;
}
trap = lock_rename(tdentry, fdentry);
fh_fill_pre_attrs(ffhp);
fh_fill_pre_attrs(tfhp);
odentry = lookup_one_len(fname, fdentry, flen);
host_err = PTR_ERR(odentry);
if (IS_ERR(odentry))
goto out_nfserr;
host_err = -ENOENT;
if (d_really_is_negative(odentry))
goto out_dput_old;
host_err = -EINVAL;
if (odentry == trap)
goto out_dput_old;
ndentry = lookup_one_len(tname, tdentry, tlen);
host_err = PTR_ERR(ndentry);
if (IS_ERR(ndentry))
goto out_dput_old;
host_err = -ENOTEMPTY;
if (ndentry == trap)
goto out_dput_new;
host_err = -EXDEV;
if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
goto out_dput_new;
if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry)
goto out_dput_new;
if ((ndentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK) &&
nfsd_has_cached_files(ndentry)) {
close_cached = true;
goto out_dput_old;
} else {
struct renamedata rd = {
.old_mnt_idmap = &nop_mnt_idmap,
.old_dir = fdir,
.old_dentry = odentry,
.new_mnt_idmap = &nop_mnt_idmap,
.new_dir = tdir,
.new_dentry = ndentry,
};
int retries;
for (retries = 1;;) {
host_err = vfs_rename(&rd);
if (host_err != -EAGAIN || !retries--)
break;
if (!nfsd_wait_for_delegreturn(rqstp, d_inode(odentry)))
break;
}
if (!host_err) {
host_err = commit_metadata(tfhp);
if (!host_err)
host_err = commit_metadata(ffhp);
}
}
out_dput_new:
dput(ndentry);
out_dput_old:
dput(odentry);
out_nfserr:
err = nfserrno(host_err);
if (!close_cached) {
fh_fill_post_attrs(ffhp);
fh_fill_post_attrs(tfhp);
}
unlock_rename(tdentry, fdentry);
fh_drop_write(ffhp);
/*
* If the target dentry has cached open files, then we need to try to
* close them prior to doing the rename. Flushing delayed fput
* shouldn't be done with locks held however, so we delay it until this
* point and then reattempt the whole shebang.
*/
if (close_cached) {
close_cached = false;
nfsd_close_cached_files(ndentry);
dput(ndentry);
goto retry;
}
out:
return err;
}
/*
* Unlink a file or directory
* N.B. After this call fhp needs an fh_put
*/
__be32
nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
char *fname, int flen)
{
struct dentry *dentry, *rdentry;
struct inode *dirp;
struct inode *rinode;
__be32 err;
int host_err;
err = nfserr_acces;
if (!flen || isdotent(fname, flen))
goto out;
err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_REMOVE);
if (err)
goto out;
host_err = fh_want_write(fhp);
if (host_err)
goto out_nfserr;
dentry = fhp->fh_dentry;
dirp = d_inode(dentry);
inode_lock_nested(dirp, I_MUTEX_PARENT);
rdentry = lookup_one_len(fname, dentry, flen);
host_err = PTR_ERR(rdentry);
if (IS_ERR(rdentry))
goto out_unlock;
if (d_really_is_negative(rdentry)) {
dput(rdentry);
host_err = -ENOENT;
goto out_unlock;
}
rinode = d_inode(rdentry);
ihold(rinode);
if (!type)
type = d_inode(rdentry)->i_mode & S_IFMT;
fh_fill_pre_attrs(fhp);
if (type != S_IFDIR) {
int retries;
if (rdentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK)
nfsd_close_cached_files(rdentry);
for (retries = 1;;) {
host_err = vfs_unlink(&nop_mnt_idmap, dirp, rdentry, NULL);
if (host_err != -EAGAIN || !retries--)
break;
if (!nfsd_wait_for_delegreturn(rqstp, rinode))
break;
}
} else {
host_err = vfs_rmdir(&nop_mnt_idmap, dirp, rdentry);
}
fh_fill_post_attrs(fhp);
inode_unlock(dirp);
if (!host_err)
host_err = commit_metadata(fhp);
dput(rdentry);
iput(rinode); /* truncate the inode here */
out_drop_write:
fh_drop_write(fhp);
out_nfserr:
if (host_err == -EBUSY) {
/* name is mounted-on. There is no perfect
* error status.
*/
if (nfsd_v4client(rqstp))
err = nfserr_file_open;
else
err = nfserr_acces;
} else {
err = nfserrno(host_err);
}
out:
return err;
out_unlock:
inode_unlock(dirp);
goto out_drop_write;
}
/*
* We do this buffering because we must not call back into the file
* system's ->lookup() method from the filldir callback. That may well
* deadlock a number of file systems.
*
* This is based heavily on the implementation of same in XFS.
*/
struct buffered_dirent {
u64 ino;
loff_t offset;
int namlen;
unsigned int d_type;
char name[];
};
struct readdir_data {
struct dir_context ctx;
char *dirent;
size_t used;
int full;
};
static bool nfsd_buffered_filldir(struct dir_context *ctx, const char *name,
int namlen, loff_t offset, u64 ino,
unsigned int d_type)
{
struct readdir_data *buf =
container_of(ctx, struct readdir_data, ctx);
struct buffered_dirent *de = (void *)(buf->dirent + buf->used);
unsigned int reclen;
reclen = ALIGN(sizeof(struct buffered_dirent) + namlen, sizeof(u64));
if (buf->used + reclen > PAGE_SIZE) {
buf->full = 1;
return false;
}
de->namlen = namlen;
de->offset = offset;
de->ino = ino;
de->d_type = d_type;
memcpy(de->name, name, namlen);
buf->used += reclen;
return true;
}
static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
nfsd_filldir_t func, struct readdir_cd *cdp,
loff_t *offsetp)
{
struct buffered_dirent *de;
int host_err;
int size;
loff_t offset;
struct readdir_data buf = {
.ctx.actor = nfsd_buffered_filldir,
.dirent = (void *)__get_free_page(GFP_KERNEL)
};
if (!buf.dirent)
return nfserrno(-ENOMEM);
offset = *offsetp;
while (1) {
unsigned int reclen;
cdp->err = nfserr_eof; /* will be cleared on successful read */
buf.used = 0;
buf.full = 0;
host_err = iterate_dir(file, &buf.ctx);
if (buf.full)
host_err = 0;
if (host_err < 0)
break;
size = buf.used;
if (!size)
break;
de = (struct buffered_dirent *)buf.dirent;
while (size > 0) {
offset = de->offset;
if (func(cdp, de->name, de->namlen, de->offset,
de->ino, de->d_type))
break;
if (cdp->err != nfs_ok)
break;
trace_nfsd_dirent(fhp, de->ino, de->name, de->namlen);
reclen = ALIGN(sizeof(*de) + de->namlen,
sizeof(u64));
size -= reclen;
de = (struct buffered_dirent *)((char *)de + reclen);
}
if (size > 0) /* We bailed out early */
break;
offset = vfs_llseek(file, 0, SEEK_CUR);
}
free_page((unsigned long)(buf.dirent));
if (host_err)
return nfserrno(host_err);
*offsetp = offset;
return cdp->err;
}
/*
* Read entries from a directory.
* The NFSv3/4 verifier we ignore for now.
*/
__be32
nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp,
struct readdir_cd *cdp, nfsd_filldir_t func)
{
__be32 err;
struct file *file;
loff_t offset = *offsetp;
int may_flags = NFSD_MAY_READ;
/* NFSv2 only supports 32 bit cookies */
if (rqstp->rq_vers > 2)
may_flags |= NFSD_MAY_64BIT_COOKIE;
err = nfsd_open(rqstp, fhp, S_IFDIR, may_flags, &file);
if (err)
goto out;
offset = vfs_llseek(file, offset, SEEK_SET);
if (offset < 0) {
err = nfserrno((int)offset);
goto out_close;
}
err = nfsd_buffered_readdir(file, fhp, func, cdp, offsetp);
if (err == nfserr_eof || err == nfserr_toosmall)
err = nfs_ok; /* can still be found in ->err */
out_close:
fput(file);
out:
return err;
}
/*
* Get file system stats
* N.B. After this call fhp needs an fh_put
*/
__be32
nfsd_statfs(struct svc_rqst *rqstp, struct svc_fh *fhp, struct kstatfs *stat, int access)
{
__be32 err;
err = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP | access);
if (!err) {
struct path path = {
.mnt = fhp->fh_export->ex_path.mnt,
.dentry = fhp->fh_dentry,
};
if (vfs_statfs(&path, stat))
err = nfserr_io;
}
return err;
}
static int exp_rdonly(struct svc_rqst *rqstp, struct svc_export *exp)
{
return nfsexp_flags(rqstp, exp) & NFSEXP_READONLY;
}
#ifdef CONFIG_NFSD_V4
/*
* Helper function to translate error numbers. In the case of xattr operations,
* some error codes need to be translated outside of the standard translations.
*
* ENODATA needs to be translated to nfserr_noxattr.
* E2BIG to nfserr_xattr2big.
*
* Additionally, vfs_listxattr can return -ERANGE. This means that the
* file has too many extended attributes to retrieve inside an
* XATTR_LIST_MAX sized buffer. This is a bug in the xattr implementation:
* filesystems will allow the adding of extended attributes until they hit
* their own internal limit. This limit may be larger than XATTR_LIST_MAX.
* So, at that point, the attributes are present and valid, but can't
* be retrieved using listxattr, since the upper level xattr code enforces
* the XATTR_LIST_MAX limit.
*
* This bug means that we need to deal with listxattr returning -ERANGE. The
* best mapping is to return TOOSMALL.
*/
static __be32
nfsd_xattr_errno(int err)
{
switch (err) {
case -ENODATA:
return nfserr_noxattr;
case -E2BIG:
return nfserr_xattr2big;
case -ERANGE:
return nfserr_toosmall;
}
return nfserrno(err);
}
/*
* Retrieve the specified user extended attribute. To avoid always
* having to allocate the maximum size (since we are not getting
* a maximum size from the RPC), do a probe + alloc. Hold a reader
* lock on i_rwsem to prevent the extended attribute from changing
* size while we're doing this.
*/
__be32
nfsd_getxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
void **bufp, int *lenp)
{
ssize_t len;
__be32 err;
char *buf;
struct inode *inode;
struct dentry *dentry;
err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
if (err)
return err;
err = nfs_ok;
dentry = fhp->fh_dentry;
inode = d_inode(dentry);
inode_lock_shared(inode);
len = vfs_getxattr(&nop_mnt_idmap, dentry, name, NULL, 0);
/*
* Zero-length attribute, just return.
*/
if (len == 0) {
*bufp = NULL;
*lenp = 0;
goto out;
}
if (len < 0) {
err = nfsd_xattr_errno(len);
goto out;
}
if (len > *lenp) {
err = nfserr_toosmall;
goto out;
}
buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
if (buf == NULL) {
err = nfserr_jukebox;
goto out;
}
len = vfs_getxattr(&nop_mnt_idmap, dentry, name, buf, len);
if (len <= 0) {
kvfree(buf);
buf = NULL;
err = nfsd_xattr_errno(len);
}
*lenp = len;
*bufp = buf;
out:
inode_unlock_shared(inode);
return err;
}
/*
* Retrieve the xattr names. Since we can't know how many are
* user extended attributes, we must get all attributes here,
* and have the XDR encode filter out the "user." ones.
*
* While this could always just allocate an XATTR_LIST_MAX
* buffer, that's a waste, so do a probe + allocate. To
* avoid any changes between the probe and allocate, wrap
* this in inode_lock.
*/
__be32
nfsd_listxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char **bufp,
int *lenp)
{
ssize_t len;
__be32 err;
char *buf;
struct inode *inode;
struct dentry *dentry;
err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
if (err)
return err;
dentry = fhp->fh_dentry;
inode = d_inode(dentry);
*lenp = 0;
inode_lock_shared(inode);
len = vfs_listxattr(dentry, NULL, 0);
if (len <= 0) {
err = nfsd_xattr_errno(len);
goto out;
}
if (len > XATTR_LIST_MAX) {
err = nfserr_xattr2big;
goto out;
}
/*
* We're holding i_rwsem - use GFP_NOFS.
*/
buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
if (buf == NULL) {
err = nfserr_jukebox;
goto out;
}
len = vfs_listxattr(dentry, buf, len);
if (len <= 0) {
kvfree(buf);
err = nfsd_xattr_errno(len);
goto out;
}
*lenp = len;
*bufp = buf;
err = nfs_ok;
out:
inode_unlock_shared(inode);
return err;
}
/**
* nfsd_removexattr - Remove an extended attribute
* @rqstp: RPC transaction being executed
* @fhp: NFS filehandle of object with xattr to remove
* @name: name of xattr to remove (NUL-terminate)
*
* Pass in a NULL pointer for delegated_inode, and let the client deal
* with NFS4ERR_DELAY (same as with e.g. setattr and remove).
*
* Returns nfs_ok on success, or an nfsstat in network byte order.
*/
__be32
nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
{
__be32 err;
int ret;
err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
if (err)
return err;
ret = fh_want_write(fhp);
if (ret)
return nfserrno(ret);
inode_lock(fhp->fh_dentry->d_inode);
fh_fill_pre_attrs(fhp);
ret = __vfs_removexattr_locked(&nop_mnt_idmap, fhp->fh_dentry,
name, NULL);
fh_fill_post_attrs(fhp);
inode_unlock(fhp->fh_dentry->d_inode);
fh_drop_write(fhp);
return nfsd_xattr_errno(ret);
}
__be32
nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
void *buf, u32 len, u32 flags)
{
__be32 err;
int ret;
err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
if (err)
return err;
ret = fh_want_write(fhp);
if (ret)
return nfserrno(ret);
inode_lock(fhp->fh_dentry->d_inode);
fh_fill_pre_attrs(fhp);
ret = __vfs_setxattr_locked(&nop_mnt_idmap, fhp->fh_dentry, name, buf,
len, flags, NULL);
fh_fill_post_attrs(fhp);
inode_unlock(fhp->fh_dentry->d_inode);
fh_drop_write(fhp);
return nfsd_xattr_errno(ret);
}
#endif
/*
* Check for a user's access permissions to this inode.
*/
__be32
nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp,
struct dentry *dentry, int acc)
{
struct inode *inode = d_inode(dentry);
int err;
if ((acc & NFSD_MAY_MASK) == NFSD_MAY_NOP)
return 0;
#if 0
dprintk("nfsd: permission 0x%x%s%s%s%s%s%s%s mode 0%o%s%s%s\n",
acc,
(acc & NFSD_MAY_READ)? " read" : "",
(acc & NFSD_MAY_WRITE)? " write" : "",
(acc & NFSD_MAY_EXEC)? " exec" : "",
(acc & NFSD_MAY_SATTR)? " sattr" : "",
(acc & NFSD_MAY_TRUNC)? " trunc" : "",
(acc & NFSD_MAY_LOCK)? " lock" : "",
(acc & NFSD_MAY_OWNER_OVERRIDE)? " owneroverride" : "",
inode->i_mode,
IS_IMMUTABLE(inode)? " immut" : "",
IS_APPEND(inode)? " append" : "",
__mnt_is_readonly(exp->ex_path.mnt)? " ro" : "");
dprintk(" owner %d/%d user %d/%d\n",
inode->i_uid, inode->i_gid, current_fsuid(), current_fsgid());
#endif
/* Normally we reject any write/sattr etc access on a read-only file
* system. But if it is IRIX doing check on write-access for a
* device special file, we ignore rofs.
*/
if (!(acc & NFSD_MAY_LOCAL_ACCESS))
if (acc & (NFSD_MAY_WRITE | NFSD_MAY_SATTR | NFSD_MAY_TRUNC)) {
if (exp_rdonly(rqstp, exp) ||
__mnt_is_readonly(exp->ex_path.mnt))
return nfserr_rofs;
if (/* (acc & NFSD_MAY_WRITE) && */ IS_IMMUTABLE(inode))
return nfserr_perm;
}
if ((acc & NFSD_MAY_TRUNC) && IS_APPEND(inode))
return nfserr_perm;
if (acc & NFSD_MAY_LOCK) {
/* If we cannot rely on authentication in NLM requests,
* just allow locks, otherwise require read permission, or
* ownership
*/
if (exp->ex_flags & NFSEXP_NOAUTHNLM)
return 0;
else
acc = NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE;
}
/*
* The file owner always gets access permission for accesses that
* would normally be checked at open time. This is to make
* file access work even when the client has done a fchmod(fd, 0).
*
* However, `cp foo bar' should fail nevertheless when bar is
* readonly. A sensible way to do this might be to reject all
* attempts to truncate a read-only file, because a creat() call
* always implies file truncation.
* ... but this isn't really fair. A process may reasonably call
* ftruncate on an open file descriptor on a file with perm 000.
* We must trust the client to do permission checking - using "ACCESS"
* with NFSv3.
*/
if ((acc & NFSD_MAY_OWNER_OVERRIDE) &&
uid_eq(inode->i_uid, current_fsuid()))
return 0;
/* This assumes NFSD_MAY_{READ,WRITE,EXEC} == MAY_{READ,WRITE,EXEC} */
err = inode_permission(&nop_mnt_idmap, inode,
acc & (MAY_READ | MAY_WRITE | MAY_EXEC));
/* Allow read access to binaries even when mode 111 */
if (err == -EACCES && S_ISREG(inode->i_mode) &&
(acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE) ||
acc == (NFSD_MAY_READ | NFSD_MAY_READ_IF_EXEC)))
err = inode_permission(&nop_mnt_idmap, inode, MAY_EXEC);
return err? nfserrno(err) : 0;
}
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