1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2012 Bryan Schumaker <bjschuma@netapp.com>
4 */
5#include <linux/init.h>
6#include <linux/module.h>
7#include <linux/mount.h>
8#include <linux/nfs4_mount.h>
9#include <linux/nfs_fs.h>
10#include <linux/nfs_ssc.h>
11#include "delegation.h"
12#include "internal.h"
13#include "nfs4_fs.h"
14#include "nfs4idmap.h"
15#include "dns_resolve.h"
16#include "pnfs.h"
17#include "nfs.h"
18
19#define NFSDBG_FACILITY		NFSDBG_VFS
20
21static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc);
22static void nfs4_evict_inode(struct inode *inode);
23
24static const struct super_operations nfs4_sops = {
25	.alloc_inode	= nfs_alloc_inode,
26	.free_inode	= nfs_free_inode,
27	.write_inode	= nfs4_write_inode,
28	.drop_inode	= nfs_drop_inode,
29	.statfs		= nfs_statfs,
30	.evict_inode	= nfs4_evict_inode,
31	.umount_begin	= nfs_umount_begin,
32	.show_options	= nfs_show_options,
33	.show_devname	= nfs_show_devname,
34	.show_path	= nfs_show_path,
35	.show_stats	= nfs_show_stats,
36};
37
38struct nfs_subversion nfs_v4 = {
39	.owner		= THIS_MODULE,
40	.nfs_fs		= &nfs4_fs_type,
41	.rpc_vers	= &nfs_version4,
42	.rpc_ops	= &nfs_v4_clientops,
43	.sops		= &nfs4_sops,
44	.xattr		= nfs4_xattr_handlers,
45};
46
47static int nfs4_write_inode(struct inode *inode, struct writeback_control *wbc)
48{
49	int ret = nfs_write_inode(inode, wbc);
50
51	if (ret == 0)
52		ret = pnfs_layoutcommit_inode(inode,
53				wbc->sync_mode == WB_SYNC_ALL);
54	return ret;
55}
56
57/*
58 * Clean out any remaining NFSv4 state that might be left over due
59 * to open() calls that passed nfs_atomic_lookup, but failed to call
60 * nfs_open().
61 */
62static void nfs4_evict_inode(struct inode *inode)
63{
64	truncate_inode_pages_final(&inode->i_data);
65	clear_inode(inode);
66	/* If we are holding a delegation, return and free it */
67	nfs_inode_evict_delegation(inode);
68	/* Note that above delegreturn would trigger pnfs return-on-close */
69	pnfs_return_layout(inode);
70	pnfs_destroy_layout_final(NFS_I(inode));
71	/* First call standard NFS clear_inode() code */
72	nfs_clear_inode(inode);
73	nfs4_xattr_cache_zap(inode);
74}
75
76struct nfs_referral_count {
77	struct list_head list;
78	const struct task_struct *task;
79	unsigned int referral_count;
80};
81
82static LIST_HEAD(nfs_referral_count_list);
83static DEFINE_SPINLOCK(nfs_referral_count_list_lock);
84
85static struct nfs_referral_count *nfs_find_referral_count(void)
86{
87	struct nfs_referral_count *p;
88
89	list_for_each_entry(p, &nfs_referral_count_list, list) {
90		if (p->task == current)
91			return p;
92	}
93	return NULL;
94}
95
96#define NFS_MAX_NESTED_REFERRALS 2
97
98static int nfs_referral_loop_protect(void)
99{
100	struct nfs_referral_count *p, *new;
101	int ret = -ENOMEM;
102
103	new = kmalloc(sizeof(*new), GFP_KERNEL);
104	if (!new)
105		goto out;
106	new->task = current;
107	new->referral_count = 1;
108
109	ret = 0;
110	spin_lock(&nfs_referral_count_list_lock);
111	p = nfs_find_referral_count();
112	if (p != NULL) {
113		if (p->referral_count >= NFS_MAX_NESTED_REFERRALS)
114			ret = -ELOOP;
115		else
116			p->referral_count++;
117	} else {
118		list_add(&new->list, &nfs_referral_count_list);
119		new = NULL;
120	}
121	spin_unlock(&nfs_referral_count_list_lock);
122	kfree(new);
123out:
124	return ret;
125}
126
127static void nfs_referral_loop_unprotect(void)
128{
129	struct nfs_referral_count *p;
130
131	spin_lock(&nfs_referral_count_list_lock);
132	p = nfs_find_referral_count();
133	p->referral_count--;
134	if (p->referral_count == 0)
135		list_del(&p->list);
136	else
137		p = NULL;
138	spin_unlock(&nfs_referral_count_list_lock);
139	kfree(p);
140}
141
142static int do_nfs4_mount(struct nfs_server *server,
143			 struct fs_context *fc,
144			 const char *hostname,
145			 const char *export_path)
146{
147	struct nfs_fs_context *root_ctx;
148	struct nfs_fs_context *ctx;
149	struct fs_context *root_fc;
150	struct vfsmount *root_mnt;
151	struct dentry *dentry;
152	size_t len;
153	int ret;
154
155	struct fs_parameter param = {
156		.key	= "source",
157		.type	= fs_value_is_string,
158		.dirfd	= -1,
159	};
160
161	struct fs_parameter param_fsc = {
162		.key	= "fsc",
163		.type	= fs_value_is_string,
164		.dirfd	= -1,
165	};
166
167	if (IS_ERR(server))
168		return PTR_ERR(server);
169
170	root_fc = vfs_dup_fs_context(fc);
171	if (IS_ERR(root_fc)) {
172		nfs_free_server(server);
173		return PTR_ERR(root_fc);
174	}
175	kfree(root_fc->source);
176	root_fc->source = NULL;
177
178	ctx = nfs_fc2context(fc);
179	root_ctx = nfs_fc2context(root_fc);
180	root_ctx->internal = true;
181	root_ctx->server = server;
182
183	if (ctx->fscache_uniq) {
184		len = strlen(ctx->fscache_uniq);
185		param_fsc.size = len;
186		param_fsc.string = kmemdup_nul(ctx->fscache_uniq, len, GFP_KERNEL);
187		if (param_fsc.string == NULL) {
188			put_fs_context(root_fc);
189			return -ENOMEM;
190		}
191		ret = vfs_parse_fs_param(root_fc, &param_fsc);
192		kfree(param_fsc.string);
193		if (ret < 0) {
194			put_fs_context(root_fc);
195			return ret;
196		}
197	}
198	/* We leave export_path unset as it's not used to find the root. */
199
200	len = strlen(hostname) + 5;
201	param.string = kmalloc(len, GFP_KERNEL);
202	if (param.string == NULL) {
203		put_fs_context(root_fc);
204		return -ENOMEM;
205	}
206
207	/* Does hostname needs to be enclosed in brackets? */
208	if (strchr(hostname, ':'))
209		param.size = snprintf(param.string, len, "[%s]:/", hostname);
210	else
211		param.size = snprintf(param.string, len, "%s:/", hostname);
212	ret = vfs_parse_fs_param(root_fc, &param);
213	kfree(param.string);
214	if (ret < 0) {
215		put_fs_context(root_fc);
216		return ret;
217	}
218	root_mnt = fc_mount(root_fc);
219	put_fs_context(root_fc);
220
221	if (IS_ERR(root_mnt))
222		return PTR_ERR(root_mnt);
223
224	ret = nfs_referral_loop_protect();
225	if (ret) {
226		mntput(root_mnt);
227		return ret;
228	}
229
230	dentry = mount_subtree(root_mnt, export_path);
231	nfs_referral_loop_unprotect();
232
233	if (IS_ERR(dentry))
234		return PTR_ERR(dentry);
235
236	fc->root = dentry;
237	return 0;
238}
239
240int nfs4_try_get_tree(struct fs_context *fc)
241{
242	struct nfs_fs_context *ctx = nfs_fc2context(fc);
243	int err;
244
245	dfprintk(MOUNT, "--> nfs4_try_get_tree()\n");
246
247	/* We create a mount for the server's root, walk to the requested
248	 * location and then create another mount for that.
249	 */
250	err= do_nfs4_mount(nfs4_create_server(fc),
251			   fc, ctx->nfs_server.hostname,
252			   ctx->nfs_server.export_path);
253	if (err) {
254		nfs_ferrorf(fc, MOUNT, "NFS4: Couldn't follow remote path");
255		dfprintk(MOUNT, "<-- nfs4_try_get_tree() = %d [error]\n", err);
256	} else {
257		dfprintk(MOUNT, "<-- nfs4_try_get_tree() = 0\n");
258	}
259	return err;
260}
261
262/*
263 * Create an NFS4 server record on referral traversal
264 */
265int nfs4_get_referral_tree(struct fs_context *fc)
266{
267	struct nfs_fs_context *ctx = nfs_fc2context(fc);
268	int err;
269
270	dprintk("--> nfs4_referral_mount()\n");
271
272	/* create a new volume representation */
273	err = do_nfs4_mount(nfs4_create_referral_server(fc),
274			    fc, ctx->nfs_server.hostname,
275			    ctx->nfs_server.export_path);
276	if (err) {
277		nfs_ferrorf(fc, MOUNT, "NFS4: Couldn't follow remote path");
278		dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = %d [error]\n", err);
279	} else {
280		dfprintk(MOUNT, "<-- nfs4_get_referral_tree() = 0\n");
281	}
282	return err;
283}
284
285static int __init init_nfs_v4(void)
286{
287	int err;
288
289	err = nfs_dns_resolver_init();
290	if (err)
291		goto out;
292
293	err = nfs_idmap_init();
294	if (err)
295		goto out1;
296
297#ifdef CONFIG_NFS_V4_2
298	err = nfs4_xattr_cache_init();
299	if (err)
300		goto out2;
301#endif
302
303	err = nfs4_register_sysctl();
304	if (err)
305		goto out2;
306
307#ifdef CONFIG_NFS_V4_2
308	nfs42_ssc_register_ops();
309#endif
310	register_nfs_version(&nfs_v4);
311	return 0;
312out2:
313	nfs_idmap_quit();
314out1:
315	nfs_dns_resolver_destroy();
316out:
317	return err;
318}
319
320static void __exit exit_nfs_v4(void)
321{
322	/* Not called in the _init(), conditionally loaded */
323	nfs4_pnfs_v3_ds_connect_unload();
324
325	unregister_nfs_version(&nfs_v4);
326#ifdef CONFIG_NFS_V4_2
327	nfs4_xattr_cache_exit();
328	nfs42_ssc_unregister_ops();
329#endif
330	nfs4_unregister_sysctl();
331	nfs_idmap_quit();
332	nfs_dns_resolver_destroy();
333}
334
335MODULE_LICENSE("GPL");
336
337module_init(init_nfs_v4);
338module_exit(exit_nfs_v4);
339