xref: /openbmc/linux/fs/9p/acl.c (revision f1575595)
1  /*
2   * Copyright IBM Corporation, 2010
3   * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
4   *
5   * This program is free software; you can redistribute it and/or modify it
6   * under the terms of version 2.1 of the GNU Lesser General Public License
7   * as published by the Free Software Foundation.
8   *
9   * This program is distributed in the hope that it would be useful, but
10   * WITHOUT ANY WARRANTY; without even the implied warranty of
11   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
12   *
13   */
14  
15  #include <linux/module.h>
16  #include <linux/fs.h>
17  #include <net/9p/9p.h>
18  #include <net/9p/client.h>
19  #include <linux/slab.h>
20  #include <linux/sched.h>
21  #include <linux/posix_acl_xattr.h>
22  #include "xattr.h"
23  #include "acl.h"
24  #include "v9fs.h"
25  #include "v9fs_vfs.h"
26  #include "fid.h"
27  
28  static struct posix_acl *__v9fs_get_acl(struct p9_fid *fid, char *name)
29  {
30  	ssize_t size;
31  	void *value = NULL;
32  	struct posix_acl *acl = NULL;
33  
34  	size = v9fs_fid_xattr_get(fid, name, NULL, 0);
35  	if (size > 0) {
36  		value = kzalloc(size, GFP_NOFS);
37  		if (!value)
38  			return ERR_PTR(-ENOMEM);
39  		size = v9fs_fid_xattr_get(fid, name, value, size);
40  		if (size > 0) {
41  			acl = posix_acl_from_xattr(&init_user_ns, value, size);
42  			if (IS_ERR(acl))
43  				goto err_out;
44  		}
45  	} else if (size == -ENODATA || size == 0 ||
46  		   size == -ENOSYS || size == -EOPNOTSUPP) {
47  		acl = NULL;
48  	} else
49  		acl = ERR_PTR(-EIO);
50  
51  err_out:
52  	kfree(value);
53  	return acl;
54  }
55  
56  int v9fs_get_acl(struct inode *inode, struct p9_fid *fid)
57  {
58  	int retval = 0;
59  	struct posix_acl *pacl, *dacl;
60  	struct v9fs_session_info *v9ses;
61  
62  	v9ses = v9fs_inode2v9ses(inode);
63  	if (((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) ||
64  			((v9ses->flags & V9FS_ACL_MASK) != V9FS_POSIX_ACL)) {
65  		set_cached_acl(inode, ACL_TYPE_DEFAULT, NULL);
66  		set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
67  		return 0;
68  	}
69  	/* get the default/access acl values and cache them */
70  	dacl = __v9fs_get_acl(fid, XATTR_NAME_POSIX_ACL_DEFAULT);
71  	pacl = __v9fs_get_acl(fid, XATTR_NAME_POSIX_ACL_ACCESS);
72  
73  	if (!IS_ERR(dacl) && !IS_ERR(pacl)) {
74  		set_cached_acl(inode, ACL_TYPE_DEFAULT, dacl);
75  		set_cached_acl(inode, ACL_TYPE_ACCESS, pacl);
76  	} else
77  		retval = -EIO;
78  
79  	if (!IS_ERR(dacl))
80  		posix_acl_release(dacl);
81  
82  	if (!IS_ERR(pacl))
83  		posix_acl_release(pacl);
84  
85  	return retval;
86  }
87  
88  static struct posix_acl *v9fs_get_cached_acl(struct inode *inode, int type)
89  {
90  	struct posix_acl *acl;
91  	/*
92  	 * 9p Always cache the acl value when
93  	 * instantiating the inode (v9fs_inode_from_fid)
94  	 */
95  	acl = get_cached_acl(inode, type);
96  	BUG_ON(is_uncached_acl(acl));
97  	return acl;
98  }
99  
100  struct posix_acl *v9fs_iop_get_acl(struct inode *inode, int type)
101  {
102  	struct v9fs_session_info *v9ses;
103  
104  	v9ses = v9fs_inode2v9ses(inode);
105  	if (((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) ||
106  			((v9ses->flags & V9FS_ACL_MASK) != V9FS_POSIX_ACL)) {
107  		/*
108  		 * On access = client  and acl = on mode get the acl
109  		 * values from the server
110  		 */
111  		return NULL;
112  	}
113  	return v9fs_get_cached_acl(inode, type);
114  
115  }
116  
117  static int v9fs_set_acl(struct p9_fid *fid, int type, struct posix_acl *acl)
118  {
119  	int retval;
120  	char *name;
121  	size_t size;
122  	void *buffer;
123  	if (!acl)
124  		return 0;
125  
126  	/* Set a setxattr request to server */
127  	size = posix_acl_xattr_size(acl->a_count);
128  	buffer = kmalloc(size, GFP_KERNEL);
129  	if (!buffer)
130  		return -ENOMEM;
131  	retval = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
132  	if (retval < 0)
133  		goto err_free_out;
134  	switch (type) {
135  	case ACL_TYPE_ACCESS:
136  		name = XATTR_NAME_POSIX_ACL_ACCESS;
137  		break;
138  	case ACL_TYPE_DEFAULT:
139  		name = XATTR_NAME_POSIX_ACL_DEFAULT;
140  		break;
141  	default:
142  		BUG();
143  	}
144  	retval = v9fs_fid_xattr_set(fid, name, buffer, size, 0);
145  err_free_out:
146  	kfree(buffer);
147  	return retval;
148  }
149  
150  int v9fs_acl_chmod(struct inode *inode, struct p9_fid *fid)
151  {
152  	int retval = 0;
153  	struct posix_acl *acl;
154  
155  	if (S_ISLNK(inode->i_mode))
156  		return -EOPNOTSUPP;
157  	acl = v9fs_get_cached_acl(inode, ACL_TYPE_ACCESS);
158  	if (acl) {
159  		retval = __posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
160  		if (retval)
161  			return retval;
162  		set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
163  		retval = v9fs_set_acl(fid, ACL_TYPE_ACCESS, acl);
164  		posix_acl_release(acl);
165  	}
166  	return retval;
167  }
168  
169  int v9fs_set_create_acl(struct inode *inode, struct p9_fid *fid,
170  			struct posix_acl *dacl, struct posix_acl *acl)
171  {
172  	set_cached_acl(inode, ACL_TYPE_DEFAULT, dacl);
173  	set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
174  	v9fs_set_acl(fid, ACL_TYPE_DEFAULT, dacl);
175  	v9fs_set_acl(fid, ACL_TYPE_ACCESS, acl);
176  	return 0;
177  }
178  
179  void v9fs_put_acl(struct posix_acl *dacl,
180  		  struct posix_acl *acl)
181  {
182  	posix_acl_release(dacl);
183  	posix_acl_release(acl);
184  }
185  
186  int v9fs_acl_mode(struct inode *dir, umode_t *modep,
187  		  struct posix_acl **dpacl, struct posix_acl **pacl)
188  {
189  	int retval = 0;
190  	umode_t mode = *modep;
191  	struct posix_acl *acl = NULL;
192  
193  	if (!S_ISLNK(mode)) {
194  		acl = v9fs_get_cached_acl(dir, ACL_TYPE_DEFAULT);
195  		if (IS_ERR(acl))
196  			return PTR_ERR(acl);
197  		if (!acl)
198  			mode &= ~current_umask();
199  	}
200  	if (acl) {
201  		if (S_ISDIR(mode))
202  			*dpacl = posix_acl_dup(acl);
203  		retval = __posix_acl_create(&acl, GFP_NOFS, &mode);
204  		if (retval < 0)
205  			return retval;
206  		if (retval > 0)
207  			*pacl = acl;
208  		else
209  			posix_acl_release(acl);
210  	}
211  	*modep  = mode;
212  	return 0;
213  }
214  
215  static int v9fs_xattr_get_acl(const struct xattr_handler *handler,
216  			      struct dentry *dentry, struct inode *inode,
217  			      const char *name, void *buffer, size_t size)
218  {
219  	struct v9fs_session_info *v9ses;
220  	struct posix_acl *acl;
221  	int error;
222  
223  	v9ses = v9fs_dentry2v9ses(dentry);
224  	/*
225  	 * We allow set/get/list of acl when access=client is not specified
226  	 */
227  	if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
228  		return v9fs_xattr_get(dentry, handler->name, buffer, size);
229  
230  	acl = v9fs_get_cached_acl(inode, handler->flags);
231  	if (IS_ERR(acl))
232  		return PTR_ERR(acl);
233  	if (acl == NULL)
234  		return -ENODATA;
235  	error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
236  	posix_acl_release(acl);
237  
238  	return error;
239  }
240  
241  static int v9fs_xattr_set_acl(const struct xattr_handler *handler,
242  			      struct dentry *dentry, struct inode *inode,
243  			      const char *name, const void *value,
244  			      size_t size, int flags)
245  {
246  	int retval;
247  	struct posix_acl *acl;
248  	struct v9fs_session_info *v9ses;
249  
250  	v9ses = v9fs_dentry2v9ses(dentry);
251  	/*
252  	 * set the attribute on the remote. Without even looking at the
253  	 * xattr value. We leave it to the server to validate
254  	 */
255  	if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
256  		return v9fs_xattr_set(dentry, handler->name, value, size,
257  				      flags);
258  
259  	if (S_ISLNK(inode->i_mode))
260  		return -EOPNOTSUPP;
261  	if (!inode_owner_or_capable(inode))
262  		return -EPERM;
263  	if (value) {
264  		/* update the cached acl value */
265  		acl = posix_acl_from_xattr(&init_user_ns, value, size);
266  		if (IS_ERR(acl))
267  			return PTR_ERR(acl);
268  		else if (acl) {
269  			retval = posix_acl_valid(inode->i_sb->s_user_ns, acl);
270  			if (retval)
271  				goto err_out;
272  		}
273  	} else
274  		acl = NULL;
275  
276  	switch (handler->flags) {
277  	case ACL_TYPE_ACCESS:
278  		if (acl) {
279  			struct iattr iattr;
280  			struct posix_acl *old_acl = acl;
281  
282  			retval = posix_acl_update_mode(inode, &iattr.ia_mode, &acl);
283  			if (retval)
284  				goto err_out;
285  			if (!acl) {
286  				/*
287  				 * ACL can be represented
288  				 * by the mode bits. So don't
289  				 * update ACL.
290  				 */
291  				posix_acl_release(old_acl);
292  				value = NULL;
293  				size = 0;
294  			}
295  			iattr.ia_valid = ATTR_MODE;
296  			/* FIXME should we update ctime ?
297  			 * What is the following setxattr update the
298  			 * mode ?
299  			 */
300  			v9fs_vfs_setattr_dotl(dentry, &iattr);
301  		}
302  		break;
303  	case ACL_TYPE_DEFAULT:
304  		if (!S_ISDIR(inode->i_mode)) {
305  			retval = acl ? -EINVAL : 0;
306  			goto err_out;
307  		}
308  		break;
309  	default:
310  		BUG();
311  	}
312  	retval = v9fs_xattr_set(dentry, handler->name, value, size, flags);
313  	if (!retval)
314  		set_cached_acl(inode, handler->flags, acl);
315  err_out:
316  	posix_acl_release(acl);
317  	return retval;
318  }
319  
320  const struct xattr_handler v9fs_xattr_acl_access_handler = {
321  	.name	= XATTR_NAME_POSIX_ACL_ACCESS,
322  	.flags	= ACL_TYPE_ACCESS,
323  	.get	= v9fs_xattr_get_acl,
324  	.set	= v9fs_xattr_set_acl,
325  };
326  
327  const struct xattr_handler v9fs_xattr_acl_default_handler = {
328  	.name	= XATTR_NAME_POSIX_ACL_DEFAULT,
329  	.flags	= ACL_TYPE_DEFAULT,
330  	.get	= v9fs_xattr_get_acl,
331  	.set	= v9fs_xattr_set_acl,
332  };
333