1// SPDX-License-Identifier: GPL-2.0
2#include <linux/fs.h>
3#include <linux/gfp.h>
4#include <linux/nfs.h>
5#include <linux/nfs3.h>
6#include <linux/nfs_fs.h>
7#include <linux/posix_acl_xattr.h>
8#include <linux/nfsacl.h>
9
10#include "internal.h"
11#include "nfs3_fs.h"
12
13#define NFSDBG_FACILITY	NFSDBG_PROC
14
15/*
16 * nfs3_prepare_get_acl, nfs3_complete_get_acl, nfs3_abort_get_acl: Helpers for
17 * caching get_acl results in a race-free way.  See fs/posix_acl.c:get_acl()
18 * for explanations.
19 */
20static void nfs3_prepare_get_acl(struct posix_acl **p)
21{
22	struct posix_acl *sentinel = uncached_acl_sentinel(current);
23
24	/* If the ACL isn't being read yet, set our sentinel. */
25	cmpxchg(p, ACL_NOT_CACHED, sentinel);
26}
27
28static void nfs3_complete_get_acl(struct posix_acl **p, struct posix_acl *acl)
29{
30	struct posix_acl *sentinel = uncached_acl_sentinel(current);
31
32	/* Only cache the ACL if our sentinel is still in place. */
33	posix_acl_dup(acl);
34	if (cmpxchg(p, sentinel, acl) != sentinel)
35		posix_acl_release(acl);
36}
37
38static void nfs3_abort_get_acl(struct posix_acl **p)
39{
40	struct posix_acl *sentinel = uncached_acl_sentinel(current);
41
42	/* Remove our sentinel upon failure. */
43	cmpxchg(p, sentinel, ACL_NOT_CACHED);
44}
45
46struct posix_acl *nfs3_get_acl(struct inode *inode, int type, bool rcu)
47{
48	struct nfs_server *server = NFS_SERVER(inode);
49	struct page *pages[NFSACL_MAXPAGES] = { };
50	struct nfs3_getaclargs args = {
51		.fh = NFS_FH(inode),
52		/* The xdr layer may allocate pages here. */
53		.pages = pages,
54	};
55	struct nfs3_getaclres res = {
56		NULL,
57	};
58	struct rpc_message msg = {
59		.rpc_argp	= &args,
60		.rpc_resp	= &res,
61	};
62	int status, count;
63
64	if (rcu)
65		return ERR_PTR(-ECHILD);
66
67	if (!nfs_server_capable(inode, NFS_CAP_ACLS))
68		return ERR_PTR(-EOPNOTSUPP);
69
70	status = nfs_revalidate_inode(inode, NFS_INO_INVALID_CHANGE);
71	if (status < 0)
72		return ERR_PTR(status);
73
74	/*
75	 * Only get the access acl when explicitly requested: We don't
76	 * need it for access decisions, and only some applications use
77	 * it. Applications which request the access acl first are not
78	 * penalized from this optimization.
79	 */
80	if (type == ACL_TYPE_ACCESS)
81		args.mask |= NFS_ACLCNT|NFS_ACL;
82	if (S_ISDIR(inode->i_mode))
83		args.mask |= NFS_DFACLCNT|NFS_DFACL;
84	if (args.mask == 0)
85		return NULL;
86
87	dprintk("NFS call getacl\n");
88	msg.rpc_proc = &server->client_acl->cl_procinfo[ACLPROC3_GETACL];
89	res.fattr = nfs_alloc_fattr();
90	if (res.fattr == NULL)
91		return ERR_PTR(-ENOMEM);
92
93	if (args.mask & NFS_ACL)
94		nfs3_prepare_get_acl(&inode->i_acl);
95	if (args.mask & NFS_DFACL)
96		nfs3_prepare_get_acl(&inode->i_default_acl);
97
98	status = rpc_call_sync(server->client_acl, &msg, 0);
99	dprintk("NFS reply getacl: %d\n", status);
100
101	/* pages may have been allocated at the xdr layer. */
102	for (count = 0; count < NFSACL_MAXPAGES && args.pages[count]; count++)
103		__free_page(args.pages[count]);
104
105	switch (status) {
106		case 0:
107			status = nfs_refresh_inode(inode, res.fattr);
108			break;
109		case -EPFNOSUPPORT:
110		case -EPROTONOSUPPORT:
111			dprintk("NFS_V3_ACL extension not supported; disabling\n");
112			server->caps &= ~NFS_CAP_ACLS;
113			fallthrough;
114		case -ENOTSUPP:
115			status = -EOPNOTSUPP;
116			goto getout;
117		default:
118			goto getout;
119	}
120	if ((args.mask & res.mask) != args.mask) {
121		status = -EIO;
122		goto getout;
123	}
124
125	if (res.acl_access != NULL) {
126		if ((posix_acl_equiv_mode(res.acl_access, NULL) == 0) ||
127		    res.acl_access->a_count == 0) {
128			posix_acl_release(res.acl_access);
129			res.acl_access = NULL;
130		}
131	}
132
133	if (res.mask & NFS_ACL)
134		nfs3_complete_get_acl(&inode->i_acl, res.acl_access);
135	else
136		forget_cached_acl(inode, ACL_TYPE_ACCESS);
137
138	if (res.mask & NFS_DFACL)
139		nfs3_complete_get_acl(&inode->i_default_acl, res.acl_default);
140	else
141		forget_cached_acl(inode, ACL_TYPE_DEFAULT);
142
143	nfs_free_fattr(res.fattr);
144	if (type == ACL_TYPE_ACCESS) {
145		posix_acl_release(res.acl_default);
146		return res.acl_access;
147	} else {
148		posix_acl_release(res.acl_access);
149		return res.acl_default;
150	}
151
152getout:
153	nfs3_abort_get_acl(&inode->i_acl);
154	nfs3_abort_get_acl(&inode->i_default_acl);
155	posix_acl_release(res.acl_access);
156	posix_acl_release(res.acl_default);
157	nfs_free_fattr(res.fattr);
158	return ERR_PTR(status);
159}
160
161static int __nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
162		struct posix_acl *dfacl)
163{
164	struct nfs_server *server = NFS_SERVER(inode);
165	struct nfs_fattr *fattr;
166	struct page *pages[NFSACL_MAXPAGES];
167	struct nfs3_setaclargs args = {
168		.inode = inode,
169		.mask = NFS_ACL,
170		.acl_access = acl,
171		.pages = pages,
172	};
173	struct rpc_message msg = {
174		.rpc_argp	= &args,
175		.rpc_resp	= &fattr,
176	};
177	int status = 0;
178
179	if (acl == NULL && (!S_ISDIR(inode->i_mode) || dfacl == NULL))
180		goto out;
181
182	status = -EOPNOTSUPP;
183	if (!nfs_server_capable(inode, NFS_CAP_ACLS))
184		goto out;
185
186	/* We are doing this here because XDR marshalling does not
187	 * return any results, it BUGs. */
188	status = -ENOSPC;
189	if (acl != NULL && acl->a_count > NFS_ACL_MAX_ENTRIES)
190		goto out;
191	if (dfacl != NULL && dfacl->a_count > NFS_ACL_MAX_ENTRIES)
192		goto out;
193	if (S_ISDIR(inode->i_mode)) {
194		args.mask |= NFS_DFACL;
195		args.acl_default = dfacl;
196		args.len = nfsacl_size(acl, dfacl);
197	} else
198		args.len = nfsacl_size(acl, NULL);
199
200	if (args.len > NFS_ACL_INLINE_BUFSIZE) {
201		unsigned int npages = 1 + ((args.len - 1) >> PAGE_SHIFT);
202
203		status = -ENOMEM;
204		do {
205			args.pages[args.npages] = alloc_page(GFP_KERNEL);
206			if (args.pages[args.npages] == NULL)
207				goto out_freepages;
208			args.npages++;
209		} while (args.npages < npages);
210	}
211
212	dprintk("NFS call setacl\n");
213	status = -ENOMEM;
214	fattr = nfs_alloc_fattr();
215	if (fattr == NULL)
216		goto out_freepages;
217
218	msg.rpc_proc = &server->client_acl->cl_procinfo[ACLPROC3_SETACL];
219	msg.rpc_resp = fattr;
220	status = rpc_call_sync(server->client_acl, &msg, 0);
221	nfs_access_zap_cache(inode);
222	nfs_zap_acl_cache(inode);
223	dprintk("NFS reply setacl: %d\n", status);
224
225	switch (status) {
226		case 0:
227			status = nfs_refresh_inode(inode, fattr);
228			break;
229		case -EPFNOSUPPORT:
230		case -EPROTONOSUPPORT:
231			dprintk("NFS_V3_ACL SETACL RPC not supported"
232					"(will not retry)\n");
233			server->caps &= ~NFS_CAP_ACLS;
234			fallthrough;
235		case -ENOTSUPP:
236			status = -EOPNOTSUPP;
237	}
238	nfs_free_fattr(fattr);
239out_freepages:
240	while (args.npages != 0) {
241		args.npages--;
242		__free_page(args.pages[args.npages]);
243	}
244out:
245	return status;
246}
247
248int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
249		struct posix_acl *dfacl)
250{
251	int ret;
252	ret = __nfs3_proc_setacls(inode, acl, dfacl);
253	return (ret == -EOPNOTSUPP) ? 0 : ret;
254
255}
256
257int nfs3_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
258		 struct posix_acl *acl, int type)
259{
260	struct posix_acl *orig = acl, *dfacl = NULL, *alloc;
261	struct inode *inode = d_inode(dentry);
262	int status;
263
264	if (S_ISDIR(inode->i_mode)) {
265		switch(type) {
266		case ACL_TYPE_ACCESS:
267			alloc = get_inode_acl(inode, ACL_TYPE_DEFAULT);
268			if (IS_ERR(alloc))
269				goto fail;
270			dfacl = alloc;
271			break;
272
273		case ACL_TYPE_DEFAULT:
274			alloc = get_inode_acl(inode, ACL_TYPE_ACCESS);
275			if (IS_ERR(alloc))
276				goto fail;
277			dfacl = acl;
278			acl = alloc;
279			break;
280		}
281	}
282
283	if (acl == NULL) {
284		alloc = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
285		if (IS_ERR(alloc))
286			goto fail;
287		acl = alloc;
288	}
289	status = __nfs3_proc_setacls(inode, acl, dfacl);
290out:
291	if (acl != orig)
292		posix_acl_release(acl);
293	if (dfacl != orig)
294		posix_acl_release(dfacl);
295	return status;
296
297fail:
298	status = PTR_ERR(alloc);
299	goto out;
300}
301
302static int
303nfs3_list_one_acl(struct inode *inode, int type, const char *name, void *data,
304		size_t size, ssize_t *result)
305{
306	struct posix_acl *acl;
307	char *p = data + *result;
308
309	acl = get_inode_acl(inode, type);
310	if (IS_ERR_OR_NULL(acl))
311		return 0;
312
313	posix_acl_release(acl);
314
315	*result += strlen(name);
316	*result += 1;
317	if (!size)
318		return 0;
319	if (*result > size)
320		return -ERANGE;
321
322	strcpy(p, name);
323	return 0;
324}
325
326ssize_t
327nfs3_listxattr(struct dentry *dentry, char *data, size_t size)
328{
329	struct inode *inode = d_inode(dentry);
330	ssize_t result = 0;
331	int error;
332
333	error = nfs3_list_one_acl(inode, ACL_TYPE_ACCESS,
334			XATTR_NAME_POSIX_ACL_ACCESS, data, size, &result);
335	if (error)
336		return error;
337
338	error = nfs3_list_one_acl(inode, ACL_TYPE_DEFAULT,
339			XATTR_NAME_POSIX_ACL_DEFAULT, data, size, &result);
340	if (error)
341		return error;
342	return result;
343}
344