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linux/fs/nfsd/vfs.c
Jeff Layton a332018a91 nfsd: handle failure to collect pre/post-op attrs more sanely 
Collecting pre_op_attrs can fail, in which case it's probably best to
fail the whole operation.

Change fh_fill_pre_attrs and fh_fill_both_attrs to return __be32, and
have the callers check the return code and abort the operation if it's
not nfs_ok.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2023-08-29 17:45:22 -04:00

2486 lines
62 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)};
unsigned int follow_flags = 0;
int err = 0;
if (exp->ex_flags & NFSEXP_CROSSMOUNT)
follow_flags = LOOKUP_AUTOMOUNT;
err = follow_down(&path, follow_flags);
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_managed(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;
iap->ia_valid |=
setattr_should_drop_sgid(&nop_mnt_idmap, inode);
}
}
}
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;;) {
struct iattr attrs;
/*
* notify_change() can alter its iattr argument, making
* @iap unsuitable for submission multiple times. Make a
* copy for every loop iteration.
*/
attrs = *iap;
host_err = __nfsd_setattr(dentry, &attrs);
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 routines
* directly. They will be released after the sending has completed.
*
* Return values: Number of bytes consumed, or -EIO if there are no
* remaining pages in rqstp->rq_pages.
*/
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++) {
/*
* Skip page replacement when extending the contents of the
* current page. But note that we may get two zero_pages in a
* row from shmem.
*/
if (page == *(rqstp->rq_next_page - 1) &&
offset_in_page(rqstp->rq_res.page_base +
rqstp->rq_res.page_len))
continue;
if (unlikely(!svc_rqst_replace_page(rqstp, page)))
return -EIO;
}
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);
}
}
/**
* nfsd_splice_read - Perform a VFS read using a splice pipe
* @rqstp: RPC transaction context
* @fhp: file handle of file to be read
* @file: opened struct file of file to be read
* @offset: starting byte offset
* @count: IN: requested number of bytes; OUT: number of bytes read
* @eof: OUT: set non-zero if operation reached the end of the file
*
* Returns nfs_ok on success, otherwise an nfserr stat value is
* returned.
*/
__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);
host_err = splice_direct_to_actor(file, &sd, nfsd_direct_splice_actor);
return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
}
/**
* nfsd_iter_read - Perform a VFS read using an iterator
* @rqstp: RPC transaction context
* @fhp: file handle of file to be read
* @file: opened struct file of file to be read
* @offset: starting byte offset
* @count: IN: requested number of bytes; OUT: number of bytes read
* @base: offset in first page of read buffer
* @eof: OUT: set non-zero if operation reached the end of the file
*
* Some filesystems or situations cannot use nfsd_splice_read. This
* function is the slightly less-performant fallback for those cases.
*
* Returns nfs_ok on success, otherwise an nfserr stat value is
* returned.
*/
__be32 nfsd_iter_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
struct file *file, loff_t offset, unsigned long *count,
unsigned int base, u32 *eof)
{
unsigned long v, total;
struct iov_iter iter;
loff_t ppos = offset;
struct page *page;
ssize_t host_err;
v = 0;
total = *count;
while (total) {
page = *(rqstp->rq_next_page++);
rqstp->rq_vec[v].iov_base = page_address(page) + base;
rqstp->rq_vec[v].iov_len = min_t(size_t, total, PAGE_SIZE - base);
total -= rqstp->rq_vec[v].iov_len;
++v;
base = 0;
}
WARN_ON_ONCE(v > ARRAY_SIZE(rqstp->rq_vec));
trace_nfsd_read_vector(rqstp, fhp, offset, *count);
iov_iter_kvec(&iter, ITER_DEST, rqstp->rq_vec, v, *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);
file_start_write(file);
host_err = vfs_iter_write(file, &iter, &pos, flags);
file_end_write(file);
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;
}
/**
* nfsd_read - Read data from a file
* @rqstp: RPC transaction context
* @fhp: file handle of file to be read
* @offset: starting byte offset
* @count: IN: requested number of bytes; OUT: number of bytes read
* @eof: OUT: set non-zero if operation reached the end of the file
*
* The caller must verify that there is enough space in @rqstp.rq_res
* to perform this operation.
*
* N.B. After this call fhp needs an fh_put
*
* Returns nfs_ok on success, otherwise an nfserr stat value is
* returned.
*/
__be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
loff_t offset, 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_iter_read(rqstp, fhp, file, offset, count, 0, 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;
err = fh_fill_pre_attrs(fhp);
if (err != nfs_ok)
goto out_unlock;
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;
}
err = fh_fill_pre_attrs(fhp);
if (err != nfs_ok)
goto out_unlock;
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);
out_unlock:
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;
err = fh_fill_pre_attrs(ffhp);
if (err != nfs_ok)
goto out_dput;
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);
err = fh_fill_pre_attrs(ffhp);
if (err != nfs_ok)
goto out_unlock;
err = fh_fill_pre_attrs(tfhp);
if (err != nfs_ok)
goto out_unlock;
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);
}
out_unlock:
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);
err = fh_fill_pre_attrs(fhp);
if (err != nfs_ok)
goto out_unlock;
ihold(rinode);
if (!type)
type = d_inode(rdentry)->i_mode & S_IFMT;
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);
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;
}
buf = kvmalloc(len, GFP_KERNEL);
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);
err = fh_fill_pre_attrs(fhp);
if (err != nfs_ok)
goto out_unlock;
ret = __vfs_removexattr_locked(&nop_mnt_idmap, fhp->fh_dentry,
name, NULL);
err = nfsd_xattr_errno(ret);
fh_fill_post_attrs(fhp);
out_unlock:
inode_unlock(fhp->fh_dentry->d_inode);
fh_drop_write(fhp);
return err;
}
__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);
err = fh_fill_pre_attrs(fhp);
if (err != nfs_ok)
goto out_unlock;
ret = __vfs_setxattr_locked(&nop_mnt_idmap, fhp->fh_dentry,
name, buf, len, flags, NULL);
fh_fill_post_attrs(fhp);
err = nfsd_xattr_errno(ret);
out_unlock:
inode_unlock(fhp->fh_dentry->d_inode);
fh_drop_write(fhp);
return err;
}
#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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