1 // SPDX-License-Identifier: LGPL-2.1
2 /*
3  * Copyright IBM Corporation, 2010
4  * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
5  */
6 
7 #include <linux/module.h>
8 #include <linux/fs.h>
9 #include <linux/sched.h>
10 #include <linux/uio.h>
11 #include <linux/posix_acl_xattr.h>
12 #include <net/9p/9p.h>
13 #include <net/9p/client.h>
14 
15 #include "fid.h"
16 #include "xattr.h"
17 
v9fs_fid_xattr_get(struct p9_fid * fid,const char * name,void * buffer,size_t buffer_size)18 ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
19 			   void *buffer, size_t buffer_size)
20 {
21 	ssize_t retval;
22 	u64 attr_size;
23 	struct p9_fid *attr_fid;
24 	struct kvec kvec = {.iov_base = buffer, .iov_len = buffer_size};
25 	struct iov_iter to;
26 	int err;
27 
28 	iov_iter_kvec(&to, ITER_DEST, &kvec, 1, buffer_size);
29 
30 	attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
31 	if (IS_ERR(attr_fid)) {
32 		retval = PTR_ERR(attr_fid);
33 		p9_debug(P9_DEBUG_VFS, "p9_client_attrwalk failed %zd\n",
34 			 retval);
35 		return retval;
36 	}
37 	if (attr_size > buffer_size) {
38 		if (buffer_size)
39 			retval = -ERANGE;
40 		else if (attr_size > SSIZE_MAX)
41 			retval = -EOVERFLOW;
42 		else /* request to get the attr_size */
43 			retval = attr_size;
44 	} else {
45 		iov_iter_truncate(&to, attr_size);
46 		retval = p9_client_read(attr_fid, 0, &to, &err);
47 		if (err)
48 			retval = err;
49 	}
50 	p9_fid_put(attr_fid);
51 	return retval;
52 }
53 
54 
55 /*
56  * v9fs_xattr_get()
57  *
58  * Copy an extended attribute into the buffer
59  * provided, or compute the buffer size required.
60  * Buffer is NULL to compute the size of the buffer required.
61  *
62  * Returns a negative error number on failure, or the number of bytes
63  * used / required on success.
64  */
v9fs_xattr_get(struct dentry * dentry,const char * name,void * buffer,size_t buffer_size)65 ssize_t v9fs_xattr_get(struct dentry *dentry, const char *name,
66 		       void *buffer, size_t buffer_size)
67 {
68 	struct p9_fid *fid;
69 	int ret;
70 
71 	p9_debug(P9_DEBUG_VFS, "name = '%s' value_len = %zu\n",
72 		 name, buffer_size);
73 	fid = v9fs_fid_lookup(dentry);
74 	if (IS_ERR(fid))
75 		return PTR_ERR(fid);
76 	ret = v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
77 	p9_fid_put(fid);
78 
79 	return ret;
80 }
81 
82 /*
83  * v9fs_xattr_set()
84  *
85  * Create, replace or remove an extended attribute for this inode. Buffer
86  * is NULL to remove an existing extended attribute, and non-NULL to
87  * either replace an existing extended attribute, or create a new extended
88  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
89  * specify that an extended attribute must exist and must not exist
90  * previous to the call, respectively.
91  *
92  * Returns 0, or a negative error number on failure.
93  */
v9fs_xattr_set(struct dentry * dentry,const char * name,const void * value,size_t value_len,int flags)94 int v9fs_xattr_set(struct dentry *dentry, const char *name,
95 		   const void *value, size_t value_len, int flags)
96 {
97 	int ret;
98 	struct p9_fid *fid;
99 
100 	fid  = v9fs_fid_lookup(dentry);
101 	if (IS_ERR(fid))
102 		return PTR_ERR(fid);
103 	ret = v9fs_fid_xattr_set(fid, name, value, value_len, flags);
104 	p9_fid_put(fid);
105 	return ret;
106 }
107 
v9fs_fid_xattr_set(struct p9_fid * fid,const char * name,const void * value,size_t value_len,int flags)108 int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
109 		   const void *value, size_t value_len, int flags)
110 {
111 	struct kvec kvec = {.iov_base = (void *)value, .iov_len = value_len};
112 	struct iov_iter from;
113 	int retval, err;
114 
115 	iov_iter_kvec(&from, ITER_SOURCE, &kvec, 1, value_len);
116 
117 	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
118 		 name, value_len, flags);
119 
120 	/* Clone it */
121 	fid = clone_fid(fid);
122 	if (IS_ERR(fid))
123 		return PTR_ERR(fid);
124 
125 	/*
126 	 * On success fid points to xattr
127 	 */
128 	retval = p9_client_xattrcreate(fid, name, value_len, flags);
129 	if (retval < 0)
130 		p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
131 			 retval);
132 	else
133 		p9_client_write(fid, 0, &from, &retval);
134 	err = p9_fid_put(fid);
135 	if (!retval && err)
136 		retval = err;
137 	return retval;
138 }
139 
v9fs_listxattr(struct dentry * dentry,char * buffer,size_t buffer_size)140 ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
141 {
142 	/* Txattrwalk with an empty string lists xattrs instead */
143 	return v9fs_xattr_get(dentry, "", buffer, buffer_size);
144 }
145 
v9fs_xattr_handler_get(const struct xattr_handler * handler,struct dentry * dentry,struct inode * inode,const char * name,void * buffer,size_t size)146 static int v9fs_xattr_handler_get(const struct xattr_handler *handler,
147 				  struct dentry *dentry, struct inode *inode,
148 				  const char *name, void *buffer, size_t size)
149 {
150 	const char *full_name = xattr_full_name(handler, name);
151 
152 	return v9fs_xattr_get(dentry, full_name, buffer, size);
153 }
154 
v9fs_xattr_handler_set(const struct xattr_handler * handler,struct mnt_idmap * idmap,struct dentry * dentry,struct inode * inode,const char * name,const void * value,size_t size,int flags)155 static int v9fs_xattr_handler_set(const struct xattr_handler *handler,
156 				  struct mnt_idmap *idmap,
157 				  struct dentry *dentry, struct inode *inode,
158 				  const char *name, const void *value,
159 				  size_t size, int flags)
160 {
161 	const char *full_name = xattr_full_name(handler, name);
162 
163 	return v9fs_xattr_set(dentry, full_name, value, size, flags);
164 }
165 
166 static struct xattr_handler v9fs_xattr_user_handler = {
167 	.prefix	= XATTR_USER_PREFIX,
168 	.get	= v9fs_xattr_handler_get,
169 	.set	= v9fs_xattr_handler_set,
170 };
171 
172 static struct xattr_handler v9fs_xattr_trusted_handler = {
173 	.prefix	= XATTR_TRUSTED_PREFIX,
174 	.get	= v9fs_xattr_handler_get,
175 	.set	= v9fs_xattr_handler_set,
176 };
177 
178 #ifdef CONFIG_9P_FS_SECURITY
179 static struct xattr_handler v9fs_xattr_security_handler = {
180 	.prefix	= XATTR_SECURITY_PREFIX,
181 	.get	= v9fs_xattr_handler_get,
182 	.set	= v9fs_xattr_handler_set,
183 };
184 #endif
185 
186 const struct xattr_handler *v9fs_xattr_handlers[] = {
187 	&v9fs_xattr_user_handler,
188 	&v9fs_xattr_trusted_handler,
189 #ifdef CONFIG_9P_FS_SECURITY
190 	&v9fs_xattr_security_handler,
191 #endif
192 	NULL
193 };
194