xref: /openbmc/linux/fs/9p/xattr.c (revision ff7b437f)
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 <linux/sched.h>
18 #include <linux/uio.h>
19 #include <net/9p/9p.h>
20 #include <net/9p/client.h>
21 
22 #include "fid.h"
23 #include "xattr.h"
24 
25 ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
26 			   void *buffer, size_t buffer_size)
27 {
28 	ssize_t retval;
29 	u64 attr_size;
30 	struct p9_fid *attr_fid;
31 	struct kvec kvec = {.iov_base = buffer, .iov_len = buffer_size};
32 	struct iov_iter to;
33 	int err;
34 
35 	iov_iter_kvec(&to, READ, &kvec, 1, buffer_size);
36 
37 	attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
38 	if (IS_ERR(attr_fid)) {
39 		retval = PTR_ERR(attr_fid);
40 		p9_debug(P9_DEBUG_VFS, "p9_client_attrwalk failed %zd\n",
41 			 retval);
42 		return retval;
43 	}
44 	if (attr_size > buffer_size) {
45 		if (!buffer_size) /* request to get the attr_size */
46 			retval = attr_size;
47 		else
48 			retval = -ERANGE;
49 	} else {
50 		iov_iter_truncate(&to, attr_size);
51 		retval = p9_client_read(attr_fid, 0, &to, &err);
52 		if (err)
53 			retval = err;
54 	}
55 	p9_client_clunk(attr_fid);
56 	return retval;
57 }
58 
59 
60 /*
61  * v9fs_xattr_get()
62  *
63  * Copy an extended attribute into the buffer
64  * provided, or compute the buffer size required.
65  * Buffer is NULL to compute the size of the buffer required.
66  *
67  * Returns a negative error number on failure, or the number of bytes
68  * used / required on success.
69  */
70 ssize_t v9fs_xattr_get(struct dentry *dentry, const char *name,
71 		       void *buffer, size_t buffer_size)
72 {
73 	struct p9_fid *fid;
74 
75 	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu\n",
76 		 name, buffer_size);
77 	fid = v9fs_fid_lookup(dentry);
78 	if (IS_ERR(fid))
79 		return PTR_ERR(fid);
80 
81 	return v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
82 }
83 
84 /*
85  * v9fs_xattr_set()
86  *
87  * Create, replace or remove an extended attribute for this inode. Buffer
88  * is NULL to remove an existing extended attribute, and non-NULL to
89  * either replace an existing extended attribute, or create a new extended
90  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
91  * specify that an extended attribute must exist and must not exist
92  * previous to the call, respectively.
93  *
94  * Returns 0, or a negative error number on failure.
95  */
96 int v9fs_xattr_set(struct dentry *dentry, const char *name,
97 		   const void *value, size_t value_len, int flags)
98 {
99 	struct p9_fid *fid = v9fs_fid_lookup(dentry);
100 	return v9fs_fid_xattr_set(fid, name, value, value_len, flags);
101 }
102 
103 int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
104 		   const void *value, size_t value_len, int flags)
105 {
106 	struct kvec kvec = {.iov_base = (void *)value, .iov_len = value_len};
107 	struct iov_iter from;
108 	int retval, err;
109 
110 	iov_iter_kvec(&from, WRITE, &kvec, 1, value_len);
111 
112 	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
113 		 name, value_len, flags);
114 
115 	/* Clone it */
116 	fid = clone_fid(fid);
117 	if (IS_ERR(fid))
118 		return PTR_ERR(fid);
119 
120 	/*
121 	 * On success fid points to xattr
122 	 */
123 	retval = p9_client_xattrcreate(fid, name, value_len, flags);
124 	if (retval < 0)
125 		p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
126 			 retval);
127 	else
128 		p9_client_write(fid, 0, &from, &retval);
129 	err = p9_client_clunk(fid);
130 	if (!retval && err)
131 		retval = err;
132 	return retval;
133 }
134 
135 ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
136 {
137 	return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
138 }
139 
140 static int v9fs_xattr_handler_get(const struct xattr_handler *handler,
141 				  struct dentry *dentry, struct inode *inode,
142 				  const char *name, void *buffer, size_t size)
143 {
144 	const char *full_name = xattr_full_name(handler, name);
145 
146 	return v9fs_xattr_get(dentry, full_name, buffer, size);
147 }
148 
149 static int v9fs_xattr_handler_set(const struct xattr_handler *handler,
150 				  struct dentry *dentry, struct inode *inode,
151 				  const char *name, const void *value,
152 				  size_t size, int flags)
153 {
154 	const char *full_name = xattr_full_name(handler, name);
155 
156 	return v9fs_xattr_set(dentry, full_name, value, size, flags);
157 }
158 
159 static struct xattr_handler v9fs_xattr_user_handler = {
160 	.prefix	= XATTR_USER_PREFIX,
161 	.get	= v9fs_xattr_handler_get,
162 	.set	= v9fs_xattr_handler_set,
163 };
164 
165 static struct xattr_handler v9fs_xattr_trusted_handler = {
166 	.prefix	= XATTR_TRUSTED_PREFIX,
167 	.get	= v9fs_xattr_handler_get,
168 	.set	= v9fs_xattr_handler_set,
169 };
170 
171 #ifdef CONFIG_9P_FS_SECURITY
172 static struct xattr_handler v9fs_xattr_security_handler = {
173 	.prefix	= XATTR_SECURITY_PREFIX,
174 	.get	= v9fs_xattr_handler_get,
175 	.set	= v9fs_xattr_handler_set,
176 };
177 #endif
178 
179 const struct xattr_handler *v9fs_xattr_handlers[] = {
180 	&v9fs_xattr_user_handler,
181 	&v9fs_xattr_trusted_handler,
182 #ifdef CONFIG_9P_FS_POSIX_ACL
183 	&v9fs_xattr_acl_access_handler,
184 	&v9fs_xattr_acl_default_handler,
185 #endif
186 #ifdef CONFIG_9P_FS_SECURITY
187 	&v9fs_xattr_security_handler,
188 #endif
189 	NULL
190 };
191