1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * linux/fs/ext2/acl.c
4  *
5  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
6  */
7 
8 #include <linux/init.h>
9 #include <linux/sched.h>
10 #include <linux/slab.h>
11 #include <linux/fs.h>
12 #include "ext2.h"
13 #include "xattr.h"
14 #include "acl.h"
15 
16 /*
17  * Convert from filesystem to in-memory representation.
18  */
19 static struct posix_acl *
ext2_acl_from_disk(const void * value,size_t size)20 ext2_acl_from_disk(const void *value, size_t size)
21 {
22 	const char *end = (char *)value + size;
23 	int n, count;
24 	struct posix_acl *acl;
25 
26 	if (!value)
27 		return NULL;
28 	if (size < sizeof(ext2_acl_header))
29 		 return ERR_PTR(-EINVAL);
30 	if (((ext2_acl_header *)value)->a_version !=
31 	    cpu_to_le32(EXT2_ACL_VERSION))
32 		return ERR_PTR(-EINVAL);
33 	value = (char *)value + sizeof(ext2_acl_header);
34 	count = ext2_acl_count(size);
35 	if (count < 0)
36 		return ERR_PTR(-EINVAL);
37 	if (count == 0)
38 		return NULL;
39 	acl = posix_acl_alloc(count, GFP_KERNEL);
40 	if (!acl)
41 		return ERR_PTR(-ENOMEM);
42 	for (n=0; n < count; n++) {
43 		ext2_acl_entry *entry =
44 			(ext2_acl_entry *)value;
45 		if ((char *)value + sizeof(ext2_acl_entry_short) > end)
46 			goto fail;
47 		acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
48 		acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
49 		switch(acl->a_entries[n].e_tag) {
50 			case ACL_USER_OBJ:
51 			case ACL_GROUP_OBJ:
52 			case ACL_MASK:
53 			case ACL_OTHER:
54 				value = (char *)value +
55 					sizeof(ext2_acl_entry_short);
56 				break;
57 
58 			case ACL_USER:
59 				value = (char *)value + sizeof(ext2_acl_entry);
60 				if ((char *)value > end)
61 					goto fail;
62 				acl->a_entries[n].e_uid =
63 					make_kuid(&init_user_ns,
64 						  le32_to_cpu(entry->e_id));
65 				break;
66 			case ACL_GROUP:
67 				value = (char *)value + sizeof(ext2_acl_entry);
68 				if ((char *)value > end)
69 					goto fail;
70 				acl->a_entries[n].e_gid =
71 					make_kgid(&init_user_ns,
72 						  le32_to_cpu(entry->e_id));
73 				break;
74 
75 			default:
76 				goto fail;
77 		}
78 	}
79 	if (value != end)
80 		goto fail;
81 	return acl;
82 
83 fail:
84 	posix_acl_release(acl);
85 	return ERR_PTR(-EINVAL);
86 }
87 
88 /*
89  * Convert from in-memory to filesystem representation.
90  */
91 static void *
ext2_acl_to_disk(const struct posix_acl * acl,size_t * size)92 ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
93 {
94 	ext2_acl_header *ext_acl;
95 	char *e;
96 	size_t n;
97 
98 	*size = ext2_acl_size(acl->a_count);
99 	ext_acl = kmalloc(sizeof(ext2_acl_header) + acl->a_count *
100 			sizeof(ext2_acl_entry), GFP_KERNEL);
101 	if (!ext_acl)
102 		return ERR_PTR(-ENOMEM);
103 	ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
104 	e = (char *)ext_acl + sizeof(ext2_acl_header);
105 	for (n=0; n < acl->a_count; n++) {
106 		const struct posix_acl_entry *acl_e = &acl->a_entries[n];
107 		ext2_acl_entry *entry = (ext2_acl_entry *)e;
108 		entry->e_tag  = cpu_to_le16(acl_e->e_tag);
109 		entry->e_perm = cpu_to_le16(acl_e->e_perm);
110 		switch(acl_e->e_tag) {
111 			case ACL_USER:
112 				entry->e_id = cpu_to_le32(
113 					from_kuid(&init_user_ns, acl_e->e_uid));
114 				e += sizeof(ext2_acl_entry);
115 				break;
116 			case ACL_GROUP:
117 				entry->e_id = cpu_to_le32(
118 					from_kgid(&init_user_ns, acl_e->e_gid));
119 				e += sizeof(ext2_acl_entry);
120 				break;
121 
122 			case ACL_USER_OBJ:
123 			case ACL_GROUP_OBJ:
124 			case ACL_MASK:
125 			case ACL_OTHER:
126 				e += sizeof(ext2_acl_entry_short);
127 				break;
128 
129 			default:
130 				goto fail;
131 		}
132 	}
133 	return (char *)ext_acl;
134 
135 fail:
136 	kfree(ext_acl);
137 	return ERR_PTR(-EINVAL);
138 }
139 
140 /*
141  * inode->i_mutex: don't care
142  */
143 struct posix_acl *
ext2_get_acl(struct inode * inode,int type)144 ext2_get_acl(struct inode *inode, int type)
145 {
146 	int name_index;
147 	char *value = NULL;
148 	struct posix_acl *acl;
149 	int retval;
150 
151 	switch (type) {
152 	case ACL_TYPE_ACCESS:
153 		name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
154 		break;
155 	case ACL_TYPE_DEFAULT:
156 		name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
157 		break;
158 	default:
159 		BUG();
160 	}
161 	retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
162 	if (retval > 0) {
163 		value = kmalloc(retval, GFP_KERNEL);
164 		if (!value)
165 			return ERR_PTR(-ENOMEM);
166 		retval = ext2_xattr_get(inode, name_index, "", value, retval);
167 	}
168 	if (retval > 0)
169 		acl = ext2_acl_from_disk(value, retval);
170 	else if (retval == -ENODATA || retval == -ENOSYS)
171 		acl = NULL;
172 	else
173 		acl = ERR_PTR(retval);
174 	kfree(value);
175 
176 	return acl;
177 }
178 
179 static int
__ext2_set_acl(struct inode * inode,struct posix_acl * acl,int type)180 __ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
181 {
182 	int name_index;
183 	void *value = NULL;
184 	size_t size = 0;
185 	int error;
186 
187 	switch(type) {
188 		case ACL_TYPE_ACCESS:
189 			name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
190 			break;
191 
192 		case ACL_TYPE_DEFAULT:
193 			name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
194 			if (!S_ISDIR(inode->i_mode))
195 				return acl ? -EACCES : 0;
196 			break;
197 
198 		default:
199 			return -EINVAL;
200 	}
201  	if (acl) {
202 		value = ext2_acl_to_disk(acl, &size);
203 		if (IS_ERR(value))
204 			return (int)PTR_ERR(value);
205 	}
206 
207 	error = ext2_xattr_set(inode, name_index, "", value, size, 0);
208 
209 	kfree(value);
210 	if (!error)
211 		set_cached_acl(inode, type, acl);
212 	return error;
213 }
214 
215 /*
216  * inode->i_mutex: down
217  */
218 int
ext2_set_acl(struct inode * inode,struct posix_acl * acl,int type)219 ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
220 {
221 	int error;
222 	int update_mode = 0;
223 	umode_t mode = inode->i_mode;
224 
225 	if (type == ACL_TYPE_ACCESS && acl) {
226 		error = posix_acl_update_mode(inode, &mode, &acl);
227 		if (error)
228 			return error;
229 		update_mode = 1;
230 	}
231 	error = __ext2_set_acl(inode, acl, type);
232 	if (!error && update_mode) {
233 		inode->i_mode = mode;
234 		inode->i_ctime = current_time(inode);
235 		mark_inode_dirty(inode);
236 	}
237 	return error;
238 }
239 
240 /*
241  * Initialize the ACLs of a new inode. Called from ext2_new_inode.
242  *
243  * dir->i_mutex: down
244  * inode->i_mutex: up (access to inode is still exclusive)
245  */
246 int
ext2_init_acl(struct inode * inode,struct inode * dir)247 ext2_init_acl(struct inode *inode, struct inode *dir)
248 {
249 	struct posix_acl *default_acl, *acl;
250 	int error;
251 
252 	error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
253 	if (error)
254 		return error;
255 
256 	if (default_acl) {
257 		error = __ext2_set_acl(inode, default_acl, ACL_TYPE_DEFAULT);
258 		posix_acl_release(default_acl);
259 	}
260 	if (acl) {
261 		if (!error)
262 			error = __ext2_set_acl(inode, acl, ACL_TYPE_ACCESS);
263 		posix_acl_release(acl);
264 	}
265 	return error;
266 }
267