xref: /openbmc/linux/fs/xfs/xfs_xattr.c (revision 089a49b6)
1 /*
2  * Copyright (C) 2008 Christoph Hellwig.
3  * Portions Copyright (C) 2000-2008 Silicon Graphics, Inc.
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU General Public License as
7  * published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope that it would be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write the Free Software Foundation,
16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
17  */
18 
19 #include "xfs.h"
20 #include "xfs_log_format.h"
21 #include "xfs_da_btree.h"
22 #include "xfs_bmap_btree.h"
23 #include "xfs_inode.h"
24 #include "xfs_attr.h"
25 #include "xfs_attr_leaf.h"
26 #include "xfs_acl.h"
27 
28 #include <linux/posix_acl_xattr.h>
29 #include <linux/xattr.h>
30 
31 
32 static int
33 xfs_xattr_get(struct dentry *dentry, const char *name,
34 		void *value, size_t size, int xflags)
35 {
36 	struct xfs_inode *ip = XFS_I(dentry->d_inode);
37 	int error, asize = size;
38 
39 	if (strcmp(name, "") == 0)
40 		return -EINVAL;
41 
42 	/* Convert Linux syscall to XFS internal ATTR flags */
43 	if (!size) {
44 		xflags |= ATTR_KERNOVAL;
45 		value = NULL;
46 	}
47 
48 	error = -xfs_attr_get(ip, (unsigned char *)name, value, &asize, xflags);
49 	if (error)
50 		return error;
51 	return asize;
52 }
53 
54 static int
55 xfs_xattr_set(struct dentry *dentry, const char *name, const void *value,
56 		size_t size, int flags, int xflags)
57 {
58 	struct xfs_inode *ip = XFS_I(dentry->d_inode);
59 
60 	if (strcmp(name, "") == 0)
61 		return -EINVAL;
62 
63 	/* Convert Linux syscall to XFS internal ATTR flags */
64 	if (flags & XATTR_CREATE)
65 		xflags |= ATTR_CREATE;
66 	if (flags & XATTR_REPLACE)
67 		xflags |= ATTR_REPLACE;
68 
69 	if (!value)
70 		return -xfs_attr_remove(ip, (unsigned char *)name, xflags);
71 	return -xfs_attr_set(ip, (unsigned char *)name,
72 				(void *)value, size, xflags);
73 }
74 
75 static const struct xattr_handler xfs_xattr_user_handler = {
76 	.prefix	= XATTR_USER_PREFIX,
77 	.flags	= 0, /* no flags implies user namespace */
78 	.get	= xfs_xattr_get,
79 	.set	= xfs_xattr_set,
80 };
81 
82 static const struct xattr_handler xfs_xattr_trusted_handler = {
83 	.prefix	= XATTR_TRUSTED_PREFIX,
84 	.flags	= ATTR_ROOT,
85 	.get	= xfs_xattr_get,
86 	.set	= xfs_xattr_set,
87 };
88 
89 static const struct xattr_handler xfs_xattr_security_handler = {
90 	.prefix	= XATTR_SECURITY_PREFIX,
91 	.flags	= ATTR_SECURE,
92 	.get	= xfs_xattr_get,
93 	.set	= xfs_xattr_set,
94 };
95 
96 const struct xattr_handler *xfs_xattr_handlers[] = {
97 	&xfs_xattr_user_handler,
98 	&xfs_xattr_trusted_handler,
99 	&xfs_xattr_security_handler,
100 #ifdef CONFIG_XFS_POSIX_ACL
101 	&xfs_xattr_acl_access_handler,
102 	&xfs_xattr_acl_default_handler,
103 #endif
104 	NULL
105 };
106 
107 static unsigned int xfs_xattr_prefix_len(int flags)
108 {
109 	if (flags & XFS_ATTR_SECURE)
110 		return sizeof("security");
111 	else if (flags & XFS_ATTR_ROOT)
112 		return sizeof("trusted");
113 	else
114 		return sizeof("user");
115 }
116 
117 static const char *xfs_xattr_prefix(int flags)
118 {
119 	if (flags & XFS_ATTR_SECURE)
120 		return xfs_xattr_security_handler.prefix;
121 	else if (flags & XFS_ATTR_ROOT)
122 		return xfs_xattr_trusted_handler.prefix;
123 	else
124 		return xfs_xattr_user_handler.prefix;
125 }
126 
127 static int
128 xfs_xattr_put_listent(
129 	struct xfs_attr_list_context *context,
130 	int		flags,
131 	unsigned char	*name,
132 	int		namelen,
133 	int		valuelen,
134 	unsigned char	*value)
135 {
136 	unsigned int prefix_len = xfs_xattr_prefix_len(flags);
137 	char *offset;
138 	int arraytop;
139 
140 	ASSERT(context->count >= 0);
141 
142 	/*
143 	 * Only show root namespace entries if we are actually allowed to
144 	 * see them.
145 	 */
146 	if ((flags & XFS_ATTR_ROOT) && !capable(CAP_SYS_ADMIN))
147 		return 0;
148 
149 	arraytop = context->count + prefix_len + namelen + 1;
150 	if (arraytop > context->firstu) {
151 		context->count = -1;	/* insufficient space */
152 		return 1;
153 	}
154 	offset = (char *)context->alist + context->count;
155 	strncpy(offset, xfs_xattr_prefix(flags), prefix_len);
156 	offset += prefix_len;
157 	strncpy(offset, (char *)name, namelen);			/* real name */
158 	offset += namelen;
159 	*offset = '\0';
160 	context->count += prefix_len + namelen + 1;
161 	return 0;
162 }
163 
164 static int
165 xfs_xattr_put_listent_sizes(
166 	struct xfs_attr_list_context *context,
167 	int		flags,
168 	unsigned char	*name,
169 	int		namelen,
170 	int		valuelen,
171 	unsigned char	*value)
172 {
173 	context->count += xfs_xattr_prefix_len(flags) + namelen + 1;
174 	return 0;
175 }
176 
177 static int
178 list_one_attr(const char *name, const size_t len, void *data,
179 		size_t size, ssize_t *result)
180 {
181 	char *p = data + *result;
182 
183 	*result += len;
184 	if (!size)
185 		return 0;
186 	if (*result > size)
187 		return -ERANGE;
188 
189 	strcpy(p, name);
190 	return 0;
191 }
192 
193 ssize_t
194 xfs_vn_listxattr(struct dentry *dentry, char *data, size_t size)
195 {
196 	struct xfs_attr_list_context context;
197 	struct attrlist_cursor_kern cursor = { 0 };
198 	struct inode		*inode = dentry->d_inode;
199 	int			error;
200 
201 	/*
202 	 * First read the regular on-disk attributes.
203 	 */
204 	memset(&context, 0, sizeof(context));
205 	context.dp = XFS_I(inode);
206 	context.cursor = &cursor;
207 	context.resynch = 1;
208 	context.alist = data;
209 	context.bufsize = size;
210 	context.firstu = context.bufsize;
211 
212 	if (size)
213 		context.put_listent = xfs_xattr_put_listent;
214 	else
215 		context.put_listent = xfs_xattr_put_listent_sizes;
216 
217 	xfs_attr_list_int(&context);
218 	if (context.count < 0)
219 		return -ERANGE;
220 
221 	/*
222 	 * Then add the two synthetic ACL attributes.
223 	 */
224 	if (posix_acl_access_exists(inode)) {
225 		error = list_one_attr(POSIX_ACL_XATTR_ACCESS,
226 				strlen(POSIX_ACL_XATTR_ACCESS) + 1,
227 				data, size, &context.count);
228 		if (error)
229 			return error;
230 	}
231 
232 	if (posix_acl_default_exists(inode)) {
233 		error = list_one_attr(POSIX_ACL_XATTR_DEFAULT,
234 				strlen(POSIX_ACL_XATTR_DEFAULT) + 1,
235 				data, size, &context.count);
236 		if (error)
237 			return error;
238 	}
239 
240 	return context.count;
241 }
242