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-rw-r--r--fs/nfs/namespace.c369
1 files changed, 369 insertions, 0 deletions
diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
new file mode 100644
index 000000000..88a23af2b
--- /dev/null
+++ b/fs/nfs/namespace.c
@@ -0,0 +1,369 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/fs/nfs/namespace.c
+ *
+ * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
+ * - Modified by David Howells <dhowells@redhat.com>
+ *
+ * NFS namespace
+ */
+
+#include <linux/module.h>
+#include <linux/dcache.h>
+#include <linux/gfp.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/nfs_fs.h>
+#include <linux/string.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/vfs.h>
+#include <linux/sunrpc/gss_api.h>
+#include "internal.h"
+#include "nfs.h"
+
+#define NFSDBG_FACILITY NFSDBG_VFS
+
+static void nfs_expire_automounts(struct work_struct *work);
+
+static LIST_HEAD(nfs_automount_list);
+static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
+int nfs_mountpoint_expiry_timeout = 500 * HZ;
+
+/*
+ * nfs_path - reconstruct the path given an arbitrary dentry
+ * @base - used to return pointer to the end of devname part of path
+ * @dentry_in - pointer to dentry
+ * @buffer - result buffer
+ * @buflen_in - length of buffer
+ * @flags - options (see below)
+ *
+ * Helper function for constructing the server pathname
+ * by arbitrary hashed dentry.
+ *
+ * This is mainly for use in figuring out the path on the
+ * server side when automounting on top of an existing partition
+ * and in generating /proc/mounts and friends.
+ *
+ * Supported flags:
+ * NFS_PATH_CANONICAL: ensure there is exactly one slash after
+ * the original device (export) name
+ * (if unset, the original name is returned verbatim)
+ */
+char *nfs_path(char **p, struct dentry *dentry_in, char *buffer,
+ ssize_t buflen_in, unsigned flags)
+{
+ char *end;
+ int namelen;
+ unsigned seq;
+ const char *base;
+ struct dentry *dentry;
+ ssize_t buflen;
+
+rename_retry:
+ buflen = buflen_in;
+ dentry = dentry_in;
+ end = buffer+buflen;
+ *--end = '\0';
+ buflen--;
+
+ seq = read_seqbegin(&rename_lock);
+ rcu_read_lock();
+ while (1) {
+ spin_lock(&dentry->d_lock);
+ if (IS_ROOT(dentry))
+ break;
+ namelen = dentry->d_name.len;
+ buflen -= namelen + 1;
+ if (buflen < 0)
+ goto Elong_unlock;
+ end -= namelen;
+ memcpy(end, dentry->d_name.name, namelen);
+ *--end = '/';
+ spin_unlock(&dentry->d_lock);
+ dentry = dentry->d_parent;
+ }
+ if (read_seqretry(&rename_lock, seq)) {
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ goto rename_retry;
+ }
+ if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
+ if (--buflen < 0) {
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ goto Elong;
+ }
+ *--end = '/';
+ }
+ *p = end;
+ base = dentry->d_fsdata;
+ if (!base) {
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ WARN_ON(1);
+ return end;
+ }
+ namelen = strlen(base);
+ if (*end == '/') {
+ /* Strip off excess slashes in base string */
+ while (namelen > 0 && base[namelen - 1] == '/')
+ namelen--;
+ }
+ buflen -= namelen;
+ if (buflen < 0) {
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ goto Elong;
+ }
+ end -= namelen;
+ memcpy(end, base, namelen);
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ return end;
+Elong_unlock:
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ if (read_seqretry(&rename_lock, seq))
+ goto rename_retry;
+Elong:
+ return ERR_PTR(-ENAMETOOLONG);
+}
+EXPORT_SYMBOL_GPL(nfs_path);
+
+/*
+ * nfs_d_automount - Handle crossing a mountpoint on the server
+ * @path - The mountpoint
+ *
+ * When we encounter a mountpoint on the server, we want to set up
+ * a mountpoint on the client too, to prevent inode numbers from
+ * colliding, and to allow "df" to work properly.
+ * On NFSv4, we also want to allow for the fact that different
+ * filesystems may be migrated to different servers in a failover
+ * situation, and that different filesystems may want to use
+ * different security flavours.
+ */
+struct vfsmount *nfs_d_automount(struct path *path)
+{
+ struct nfs_fs_context *ctx;
+ struct fs_context *fc;
+ struct vfsmount *mnt = ERR_PTR(-ENOMEM);
+ struct nfs_server *server = NFS_SB(path->dentry->d_sb);
+ struct nfs_client *client = server->nfs_client;
+ int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout);
+ int ret;
+
+ if (IS_ROOT(path->dentry))
+ return ERR_PTR(-ESTALE);
+
+ /* Open a new filesystem context, transferring parameters from the
+ * parent superblock, including the network namespace.
+ */
+ fc = fs_context_for_submount(path->mnt->mnt_sb->s_type, path->dentry);
+ if (IS_ERR(fc))
+ return ERR_CAST(fc);
+
+ ctx = nfs_fc2context(fc);
+ ctx->clone_data.dentry = path->dentry;
+ ctx->clone_data.sb = path->dentry->d_sb;
+ ctx->clone_data.fattr = nfs_alloc_fattr();
+ if (!ctx->clone_data.fattr)
+ goto out_fc;
+
+ if (fc->net_ns != client->cl_net) {
+ put_net(fc->net_ns);
+ fc->net_ns = get_net(client->cl_net);
+ }
+
+ /* for submounts we want the same server; referrals will reassign */
+ memcpy(&ctx->nfs_server._address, &client->cl_addr, client->cl_addrlen);
+ ctx->nfs_server.addrlen = client->cl_addrlen;
+ ctx->nfs_server.port = server->port;
+
+ ctx->version = client->rpc_ops->version;
+ ctx->minorversion = client->cl_minorversion;
+ ctx->nfs_mod = client->cl_nfs_mod;
+ __module_get(ctx->nfs_mod->owner);
+
+ ret = client->rpc_ops->submount(fc, server);
+ if (ret < 0) {
+ mnt = ERR_PTR(ret);
+ goto out_fc;
+ }
+
+ up_write(&fc->root->d_sb->s_umount);
+ mnt = vfs_create_mount(fc);
+ if (IS_ERR(mnt))
+ goto out_fc;
+
+ mntget(mnt); /* prevent immediate expiration */
+ if (timeout <= 0)
+ goto out_fc;
+
+ mnt_set_expiry(mnt, &nfs_automount_list);
+ schedule_delayed_work(&nfs_automount_task, timeout);
+
+out_fc:
+ put_fs_context(fc);
+ return mnt;
+}
+
+static int
+nfs_namespace_getattr(struct user_namespace *mnt_userns,
+ const struct path *path, struct kstat *stat,
+ u32 request_mask, unsigned int query_flags)
+{
+ if (NFS_FH(d_inode(path->dentry))->size != 0)
+ return nfs_getattr(mnt_userns, path, stat, request_mask,
+ query_flags);
+ generic_fillattr(&init_user_ns, d_inode(path->dentry), stat);
+ return 0;
+}
+
+static int
+nfs_namespace_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+ struct iattr *attr)
+{
+ if (NFS_FH(d_inode(dentry))->size != 0)
+ return nfs_setattr(mnt_userns, dentry, attr);
+ return -EACCES;
+}
+
+const struct inode_operations nfs_mountpoint_inode_operations = {
+ .getattr = nfs_getattr,
+ .setattr = nfs_setattr,
+};
+
+const struct inode_operations nfs_referral_inode_operations = {
+ .getattr = nfs_namespace_getattr,
+ .setattr = nfs_namespace_setattr,
+};
+
+static void nfs_expire_automounts(struct work_struct *work)
+{
+ struct list_head *list = &nfs_automount_list;
+ int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout);
+
+ mark_mounts_for_expiry(list);
+ if (!list_empty(list) && timeout > 0)
+ schedule_delayed_work(&nfs_automount_task, timeout);
+}
+
+void nfs_release_automount_timer(void)
+{
+ if (list_empty(&nfs_automount_list))
+ cancel_delayed_work(&nfs_automount_task);
+}
+
+/**
+ * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
+ * @fc: pointer to struct nfs_fs_context
+ *
+ */
+int nfs_do_submount(struct fs_context *fc)
+{
+ struct nfs_fs_context *ctx = nfs_fc2context(fc);
+ struct dentry *dentry = ctx->clone_data.dentry;
+ struct nfs_server *server;
+ char *buffer, *p;
+ int ret;
+
+ /* create a new volume representation */
+ server = ctx->nfs_mod->rpc_ops->clone_server(NFS_SB(ctx->clone_data.sb),
+ ctx->mntfh,
+ ctx->clone_data.fattr,
+ ctx->selected_flavor);
+
+ if (IS_ERR(server))
+ return PTR_ERR(server);
+
+ ctx->server = server;
+
+ buffer = kmalloc(4096, GFP_USER);
+ if (!buffer)
+ return -ENOMEM;
+
+ ctx->internal = true;
+ ctx->clone_data.inherited_bsize = ctx->clone_data.sb->s_blocksize_bits;
+
+ p = nfs_devname(dentry, buffer, 4096);
+ if (IS_ERR(p)) {
+ nfs_errorf(fc, "NFS: Couldn't determine submount pathname");
+ ret = PTR_ERR(p);
+ } else {
+ ret = vfs_parse_fs_string(fc, "source", p, buffer + 4096 - p);
+ if (!ret)
+ ret = vfs_get_tree(fc);
+ }
+ kfree(buffer);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(nfs_do_submount);
+
+int nfs_submount(struct fs_context *fc, struct nfs_server *server)
+{
+ struct nfs_fs_context *ctx = nfs_fc2context(fc);
+ struct dentry *dentry = ctx->clone_data.dentry;
+ struct dentry *parent = dget_parent(dentry);
+ int err;
+
+ /* Look it up again to get its attributes */
+ err = server->nfs_client->rpc_ops->lookup(d_inode(parent), dentry,
+ ctx->mntfh, ctx->clone_data.fattr);
+ dput(parent);
+ if (err != 0)
+ return err;
+
+ ctx->selected_flavor = server->client->cl_auth->au_flavor;
+ return nfs_do_submount(fc);
+}
+EXPORT_SYMBOL_GPL(nfs_submount);
+
+static int param_set_nfs_timeout(const char *val, const struct kernel_param *kp)
+{
+ long num;
+ int ret;
+
+ if (!val)
+ return -EINVAL;
+ ret = kstrtol(val, 0, &num);
+ if (ret)
+ return -EINVAL;
+ if (num > 0) {
+ if (num >= INT_MAX / HZ)
+ num = INT_MAX;
+ else
+ num *= HZ;
+ *((int *)kp->arg) = num;
+ if (!list_empty(&nfs_automount_list))
+ mod_delayed_work(system_wq, &nfs_automount_task, num);
+ } else {
+ *((int *)kp->arg) = -1*HZ;
+ cancel_delayed_work(&nfs_automount_task);
+ }
+ return 0;
+}
+
+static int param_get_nfs_timeout(char *buffer, const struct kernel_param *kp)
+{
+ long num = *((int *)kp->arg);
+
+ if (num > 0) {
+ if (num >= INT_MAX - (HZ - 1))
+ num = INT_MAX / HZ;
+ else
+ num = (num + (HZ - 1)) / HZ;
+ } else
+ num = -1;
+ return scnprintf(buffer, PAGE_SIZE, "%li\n", num);
+}
+
+static const struct kernel_param_ops param_ops_nfs_timeout = {
+ .set = param_set_nfs_timeout,
+ .get = param_get_nfs_timeout,
+};
+#define param_check_nfs_timeout(name, p) __param_check(name, p, int)
+
+module_param(nfs_mountpoint_expiry_timeout, nfs_timeout, 0644);
+MODULE_PARM_DESC(nfs_mountpoint_expiry_timeout,
+ "Set the NFS automounted mountpoint timeout value (seconds)."
+ "Values <= 0 turn expiration off.");