xref: /openbmc/linux/fs/nfs/nfs3acl.c (revision f9641a36)
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  */
nfs3_prepare_get_acl(struct posix_acl ** p)20 static 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 
nfs3_complete_get_acl(struct posix_acl ** p,struct posix_acl * acl)28 static 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 
nfs3_abort_get_acl(struct posix_acl ** p)38 static 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 
nfs3_get_acl(struct inode * inode,int type,bool rcu)46 struct 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 
152 getout:
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 
__nfs3_proc_setacls(struct inode * inode,struct posix_acl * acl,struct posix_acl * dfacl)161 static 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);
239 out_freepages:
240 	while (args.npages != 0) {
241 		args.npages--;
242 		__free_page(args.pages[args.npages]);
243 	}
244 out:
245 	return status;
246 }
247 
nfs3_proc_setacls(struct inode * inode,struct posix_acl * acl,struct posix_acl * dfacl)248 int 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 
nfs3_set_acl(struct mnt_idmap * idmap,struct dentry * dentry,struct posix_acl * acl,int type)257 int 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);
290 out:
291 	if (acl != orig)
292 		posix_acl_release(acl);
293 	if (dfacl != orig)
294 		posix_acl_release(dfacl);
295 	return status;
296 
297 fail:
298 	status = PTR_ERR(alloc);
299 	goto out;
300 }
301 
302 static int
nfs3_list_one_acl(struct inode * inode,int type,const char * name,void * data,size_t size,ssize_t * result)303 nfs3_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 
326 ssize_t
nfs3_listxattr(struct dentry * dentry,char * data,size_t size)327 nfs3_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