xref: /openbmc/linux/fs/9p/xattr.c (revision b5f184fbdb03b4fcc1141de34dd5ec964ca5d99e)
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  	int ret;
75  
76  	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu\n",
77  		 name, buffer_size);
78  	fid = v9fs_fid_lookup(dentry);
79  	if (IS_ERR(fid))
80  		return PTR_ERR(fid);
81  	ret = v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
82  	p9_client_clunk(fid);
83  
84  	return ret;
85  }
86  
87  /*
88   * v9fs_xattr_set()
89   *
90   * Create, replace or remove an extended attribute for this inode. Buffer
91   * is NULL to remove an existing extended attribute, and non-NULL to
92   * either replace an existing extended attribute, or create a new extended
93   * attribute. The flags XATTR_REPLACE and XATTR_CREATE
94   * specify that an extended attribute must exist and must not exist
95   * previous to the call, respectively.
96   *
97   * Returns 0, or a negative error number on failure.
98   */
99  int v9fs_xattr_set(struct dentry *dentry, const char *name,
100  		   const void *value, size_t value_len, int flags)
101  {
102  	int ret;
103  	struct p9_fid *fid;
104  
105  	fid  = v9fs_fid_lookup(dentry);
106  	if (IS_ERR(fid))
107  		return PTR_ERR(fid);
108  	ret = v9fs_fid_xattr_set(fid, name, value, value_len, flags);
109  	p9_client_clunk(fid);
110  	return ret;
111  }
112  
113  int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
114  		   const void *value, size_t value_len, int flags)
115  {
116  	struct kvec kvec = {.iov_base = (void *)value, .iov_len = value_len};
117  	struct iov_iter from;
118  	int retval, err;
119  
120  	iov_iter_kvec(&from, WRITE, &kvec, 1, value_len);
121  
122  	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
123  		 name, value_len, flags);
124  
125  	/* Clone it */
126  	fid = clone_fid(fid);
127  	if (IS_ERR(fid))
128  		return PTR_ERR(fid);
129  
130  	/*
131  	 * On success fid points to xattr
132  	 */
133  	retval = p9_client_xattrcreate(fid, name, value_len, flags);
134  	if (retval < 0)
135  		p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
136  			 retval);
137  	else
138  		p9_client_write(fid, 0, &from, &retval);
139  	err = p9_client_clunk(fid);
140  	if (!retval && err)
141  		retval = err;
142  	return retval;
143  }
144  
145  ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
146  {
147  	return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
148  }
149  
150  static int v9fs_xattr_handler_get(const struct xattr_handler *handler,
151  				  struct dentry *dentry, struct inode *inode,
152  				  const char *name, void *buffer, size_t size)
153  {
154  	const char *full_name = xattr_full_name(handler, name);
155  
156  	return v9fs_xattr_get(dentry, full_name, buffer, size);
157  }
158  
159  static int v9fs_xattr_handler_set(const struct xattr_handler *handler,
160  				  struct dentry *dentry, struct inode *inode,
161  				  const char *name, const void *value,
162  				  size_t size, int flags)
163  {
164  	const char *full_name = xattr_full_name(handler, name);
165  
166  	return v9fs_xattr_set(dentry, full_name, value, size, flags);
167  }
168  
169  static struct xattr_handler v9fs_xattr_user_handler = {
170  	.prefix	= XATTR_USER_PREFIX,
171  	.get	= v9fs_xattr_handler_get,
172  	.set	= v9fs_xattr_handler_set,
173  };
174  
175  static struct xattr_handler v9fs_xattr_trusted_handler = {
176  	.prefix	= XATTR_TRUSTED_PREFIX,
177  	.get	= v9fs_xattr_handler_get,
178  	.set	= v9fs_xattr_handler_set,
179  };
180  
181  #ifdef CONFIG_9P_FS_SECURITY
182  static struct xattr_handler v9fs_xattr_security_handler = {
183  	.prefix	= XATTR_SECURITY_PREFIX,
184  	.get	= v9fs_xattr_handler_get,
185  	.set	= v9fs_xattr_handler_set,
186  };
187  #endif
188  
189  const struct xattr_handler *v9fs_xattr_handlers[] = {
190  	&v9fs_xattr_user_handler,
191  	&v9fs_xattr_trusted_handler,
192  #ifdef CONFIG_9P_FS_POSIX_ACL
193  	&v9fs_xattr_acl_access_handler,
194  	&v9fs_xattr_acl_default_handler,
195  #endif
196  #ifdef CONFIG_9P_FS_SECURITY
197  	&v9fs_xattr_security_handler,
198  #endif
199  	NULL
200  };
201