1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2008 Christoph Hellwig.
4  * Portions Copyright (C) 2000-2008 Silicon Graphics, Inc.
5  */
6 
7 #include "xfs.h"
8 #include "xfs_format.h"
9 #include "xfs_log_format.h"
10 #include "xfs_trans_resv.h"
11 #include "xfs_mount.h"
12 #include "xfs_da_format.h"
13 #include "xfs_inode.h"
14 #include "xfs_attr.h"
15 #include "xfs_attr_leaf.h"
16 #include "xfs_acl.h"
17 
18 #include <linux/posix_acl_xattr.h>
19 #include <linux/xattr.h>
20 
21 
22 static int
xfs_xattr_get(const struct xattr_handler * handler,struct dentry * unused,struct inode * inode,const char * name,void * value,size_t size)23 xfs_xattr_get(const struct xattr_handler *handler, struct dentry *unused,
24 		struct inode *inode, const char *name, void *value, size_t size)
25 {
26 	int xflags = handler->flags;
27 	struct xfs_inode *ip = XFS_I(inode);
28 	int error, asize = size;
29 
30 	/* Convert Linux syscall to XFS internal ATTR flags */
31 	if (!size) {
32 		xflags |= ATTR_KERNOVAL;
33 		value = NULL;
34 	}
35 
36 	error = xfs_attr_get(ip, (unsigned char *)name, value, &asize, xflags);
37 	if (error)
38 		return error;
39 	return asize;
40 }
41 
42 void
xfs_forget_acl(struct inode * inode,const char * name,int xflags)43 xfs_forget_acl(
44 	struct inode		*inode,
45 	const char		*name,
46 	int			xflags)
47 {
48 	/*
49 	 * Invalidate any cached ACLs if the user has bypassed the ACL
50 	 * interface. We don't validate the content whatsoever so it is caller
51 	 * responsibility to provide data in valid format and ensure i_mode is
52 	 * consistent.
53 	 */
54 	if (xflags & ATTR_ROOT) {
55 #ifdef CONFIG_XFS_POSIX_ACL
56 		if (!strcmp(name, SGI_ACL_FILE))
57 			forget_cached_acl(inode, ACL_TYPE_ACCESS);
58 		else if (!strcmp(name, SGI_ACL_DEFAULT))
59 			forget_cached_acl(inode, ACL_TYPE_DEFAULT);
60 #endif
61 	}
62 }
63 
64 static int
xfs_xattr_set(const struct xattr_handler * handler,struct dentry * unused,struct inode * inode,const char * name,const void * value,size_t size,int flags)65 xfs_xattr_set(const struct xattr_handler *handler, struct dentry *unused,
66 		struct inode *inode, const char *name, const void *value,
67 		size_t size, int flags)
68 {
69 	int			xflags = handler->flags;
70 	struct xfs_inode	*ip = XFS_I(inode);
71 	int			error;
72 
73 	/* Convert Linux syscall to XFS internal ATTR flags */
74 	if (flags & XATTR_CREATE)
75 		xflags |= ATTR_CREATE;
76 	if (flags & XATTR_REPLACE)
77 		xflags |= ATTR_REPLACE;
78 
79 	if (!value)
80 		return xfs_attr_remove(ip, (unsigned char *)name, xflags);
81 	error = xfs_attr_set(ip, (unsigned char *)name,
82 				(void *)value, size, xflags);
83 	if (!error)
84 		xfs_forget_acl(inode, name, xflags);
85 
86 	return error;
87 }
88 
89 static const struct xattr_handler xfs_xattr_user_handler = {
90 	.prefix	= XATTR_USER_PREFIX,
91 	.flags	= 0, /* no flags implies user namespace */
92 	.get	= xfs_xattr_get,
93 	.set	= xfs_xattr_set,
94 };
95 
96 static const struct xattr_handler xfs_xattr_trusted_handler = {
97 	.prefix	= XATTR_TRUSTED_PREFIX,
98 	.flags	= ATTR_ROOT,
99 	.get	= xfs_xattr_get,
100 	.set	= xfs_xattr_set,
101 };
102 
103 static const struct xattr_handler xfs_xattr_security_handler = {
104 	.prefix	= XATTR_SECURITY_PREFIX,
105 	.flags	= ATTR_SECURE,
106 	.get	= xfs_xattr_get,
107 	.set	= xfs_xattr_set,
108 };
109 
110 const struct xattr_handler *xfs_xattr_handlers[] = {
111 	&xfs_xattr_user_handler,
112 	&xfs_xattr_trusted_handler,
113 	&xfs_xattr_security_handler,
114 #ifdef CONFIG_XFS_POSIX_ACL
115 	&posix_acl_access_xattr_handler,
116 	&posix_acl_default_xattr_handler,
117 #endif
118 	NULL
119 };
120 
121 static void
__xfs_xattr_put_listent(struct xfs_attr_list_context * context,char * prefix,int prefix_len,unsigned char * name,int namelen)122 __xfs_xattr_put_listent(
123 	struct xfs_attr_list_context *context,
124 	char *prefix,
125 	int prefix_len,
126 	unsigned char *name,
127 	int namelen)
128 {
129 	char *offset;
130 	int arraytop;
131 
132 	if (context->count < 0 || context->seen_enough)
133 		return;
134 
135 	if (!context->alist)
136 		goto compute_size;
137 
138 	arraytop = context->count + prefix_len + namelen + 1;
139 	if (arraytop > context->firstu) {
140 		context->count = -1;	/* insufficient space */
141 		context->seen_enough = 1;
142 		return;
143 	}
144 	offset = (char *)context->alist + context->count;
145 	strncpy(offset, prefix, prefix_len);
146 	offset += prefix_len;
147 	strncpy(offset, (char *)name, namelen);			/* real name */
148 	offset += namelen;
149 	*offset = '\0';
150 
151 compute_size:
152 	context->count += prefix_len + namelen + 1;
153 	return;
154 }
155 
156 static void
xfs_xattr_put_listent(struct xfs_attr_list_context * context,int flags,unsigned char * name,int namelen,int valuelen)157 xfs_xattr_put_listent(
158 	struct xfs_attr_list_context *context,
159 	int		flags,
160 	unsigned char	*name,
161 	int		namelen,
162 	int		valuelen)
163 {
164 	char *prefix;
165 	int prefix_len;
166 
167 	ASSERT(context->count >= 0);
168 
169 	if (flags & XFS_ATTR_ROOT) {
170 #ifdef CONFIG_XFS_POSIX_ACL
171 		if (namelen == SGI_ACL_FILE_SIZE &&
172 		    strncmp(name, SGI_ACL_FILE,
173 			    SGI_ACL_FILE_SIZE) == 0) {
174 			__xfs_xattr_put_listent(
175 					context, XATTR_SYSTEM_PREFIX,
176 					XATTR_SYSTEM_PREFIX_LEN,
177 					XATTR_POSIX_ACL_ACCESS,
178 					strlen(XATTR_POSIX_ACL_ACCESS));
179 		} else if (namelen == SGI_ACL_DEFAULT_SIZE &&
180 			 strncmp(name, SGI_ACL_DEFAULT,
181 				 SGI_ACL_DEFAULT_SIZE) == 0) {
182 			__xfs_xattr_put_listent(
183 					context, XATTR_SYSTEM_PREFIX,
184 					XATTR_SYSTEM_PREFIX_LEN,
185 					XATTR_POSIX_ACL_DEFAULT,
186 					strlen(XATTR_POSIX_ACL_DEFAULT));
187 		}
188 #endif
189 
190 		/*
191 		 * Only show root namespace entries if we are actually allowed to
192 		 * see them.
193 		 */
194 		if (!capable(CAP_SYS_ADMIN))
195 			return;
196 
197 		prefix = XATTR_TRUSTED_PREFIX;
198 		prefix_len = XATTR_TRUSTED_PREFIX_LEN;
199 	} else if (flags & XFS_ATTR_SECURE) {
200 		prefix = XATTR_SECURITY_PREFIX;
201 		prefix_len = XATTR_SECURITY_PREFIX_LEN;
202 	} else {
203 		prefix = XATTR_USER_PREFIX;
204 		prefix_len = XATTR_USER_PREFIX_LEN;
205 	}
206 
207 	__xfs_xattr_put_listent(context, prefix, prefix_len, name,
208 				namelen);
209 	return;
210 }
211 
212 ssize_t
xfs_vn_listxattr(struct dentry * dentry,char * data,size_t size)213 xfs_vn_listxattr(
214 	struct dentry	*dentry,
215 	char		*data,
216 	size_t		size)
217 {
218 	struct xfs_attr_list_context context;
219 	struct attrlist_cursor_kern cursor = { 0 };
220 	struct inode	*inode = d_inode(dentry);
221 	int		error;
222 
223 	/*
224 	 * First read the regular on-disk attributes.
225 	 */
226 	memset(&context, 0, sizeof(context));
227 	context.dp = XFS_I(inode);
228 	context.cursor = &cursor;
229 	context.resynch = 1;
230 	context.alist = size ? data : NULL;
231 	context.bufsize = size;
232 	context.firstu = context.bufsize;
233 	context.put_listent = xfs_xattr_put_listent;
234 
235 	error = xfs_attr_list_int(&context);
236 	if (error)
237 		return error;
238 	if (context.count < 0)
239 		return -ERANGE;
240 
241 	return context.count;
242 }
243