diff options
Diffstat (limited to 'fs/nfsd/vfs.c')
| -rw-r--r-- | fs/nfsd/vfs.c | 2476 |
1 files changed, 2476 insertions, 0 deletions
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c new file mode 100644 index 0000000000..d0fdf70ab2 --- /dev/null +++ b/fs/nfsd/vfs.c @@ -0,0 +1,2476 @@ +// 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_get_ctime(inode).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 int +__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; + int host_err = -EPERM; + + path.mnt = fhp->fh_export->ex_path.mnt; + path.dentry = fhp->fh_dentry; + inode = d_inode(path.dentry); + + 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; + + 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; + } + + host_err = ima_file_check(file, may_flags); + if (host_err) { + fput(file); + goto out; + } + + if (may_flags & NFSD_MAY_64BIT_COOKIE) + file->f_mode |= FMODE_64BITHASH; + else + file->f_mode |= FMODE_32BITHASH; + + *filp = file; +out: + return host_err; +} + +__be32 +nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, + int may_flags, struct file **filp) +{ + __be32 err; + int host_err; + bool retried = false; + + /* + * 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) { + host_err = __nfsd_open(rqstp, fhp, type, may_flags, filp); + if (host_err == -EOPENSTALE && !retried) { + retried = true; + fh_put(fhp); + goto retry; + } + err = nfserrno(host_err); + } + 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 zero on success, or a negative errno value. + */ +int +nfsd_open_verified(struct svc_rqst *rqstp, struct svc_fh *fhp, int may_flags, + struct file **filp) +{ + return __nfsd_open(rqstp, fhp, S_IFREG, may_flags, filp); +} + +/* + * 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; + + err = (rqstp->rq_vers == 2) ? nfserr_acces : nfserr_xdev; + if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt) + goto out; + if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry) + 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; + + 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; +} |