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,bool rcu)144 ext2_get_acl(struct inode *inode, int type, bool rcu)
145 {
146 	int name_index;
147 	char *value = NULL;
148 	struct posix_acl *acl;
149 	int retval;
150 
151 	if (rcu)
152 		return ERR_PTR(-ECHILD);
153 
154 	switch (type) {
155 	case ACL_TYPE_ACCESS:
156 		name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
157 		break;
158 	case ACL_TYPE_DEFAULT:
159 		name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
160 		break;
161 	default:
162 		BUG();
163 	}
164 	retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
165 	if (retval > 0) {
166 		value = kmalloc(retval, GFP_KERNEL);
167 		if (!value)
168 			return ERR_PTR(-ENOMEM);
169 		retval = ext2_xattr_get(inode, name_index, "", value, retval);
170 	}
171 	if (retval > 0)
172 		acl = ext2_acl_from_disk(value, retval);
173 	else if (retval == -ENODATA || retval == -ENOSYS)
174 		acl = NULL;
175 	else
176 		acl = ERR_PTR(retval);
177 	kfree(value);
178 
179 	return acl;
180 }
181 
182 static int
__ext2_set_acl(struct inode * inode,struct posix_acl * acl,int type)183 __ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
184 {
185 	int name_index;
186 	void *value = NULL;
187 	size_t size = 0;
188 	int error;
189 
190 	switch(type) {
191 		case ACL_TYPE_ACCESS:
192 			name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
193 			break;
194 
195 		case ACL_TYPE_DEFAULT:
196 			name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
197 			if (!S_ISDIR(inode->i_mode))
198 				return acl ? -EACCES : 0;
199 			break;
200 
201 		default:
202 			return -EINVAL;
203 	}
204  	if (acl) {
205 		value = ext2_acl_to_disk(acl, &size);
206 		if (IS_ERR(value))
207 			return (int)PTR_ERR(value);
208 	}
209 
210 	error = ext2_xattr_set(inode, name_index, "", value, size, 0);
211 
212 	kfree(value);
213 	if (!error)
214 		set_cached_acl(inode, type, acl);
215 	return error;
216 }
217 
218 /*
219  * inode->i_mutex: down
220  */
221 int
ext2_set_acl(struct user_namespace * mnt_userns,struct inode * inode,struct posix_acl * acl,int type)222 ext2_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
223 	     struct posix_acl *acl, int type)
224 {
225 	int error;
226 	int update_mode = 0;
227 	umode_t mode = inode->i_mode;
228 
229 	if (type == ACL_TYPE_ACCESS && acl) {
230 		error = posix_acl_update_mode(&init_user_ns, inode, &mode,
231 					      &acl);
232 		if (error)
233 			return error;
234 		update_mode = 1;
235 	}
236 	error = __ext2_set_acl(inode, acl, type);
237 	if (!error && update_mode) {
238 		inode->i_mode = mode;
239 		inode->i_ctime = current_time(inode);
240 		mark_inode_dirty(inode);
241 	}
242 	return error;
243 }
244 
245 /*
246  * Initialize the ACLs of a new inode. Called from ext2_new_inode.
247  *
248  * dir->i_mutex: down
249  * inode->i_mutex: up (access to inode is still exclusive)
250  */
251 int
ext2_init_acl(struct inode * inode,struct inode * dir)252 ext2_init_acl(struct inode *inode, struct inode *dir)
253 {
254 	struct posix_acl *default_acl, *acl;
255 	int error;
256 
257 	error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
258 	if (error)
259 		return error;
260 
261 	if (default_acl) {
262 		error = __ext2_set_acl(inode, default_acl, ACL_TYPE_DEFAULT);
263 		posix_acl_release(default_acl);
264 	} else {
265 		inode->i_default_acl = NULL;
266 	}
267 	if (acl) {
268 		if (!error)
269 			error = __ext2_set_acl(inode, acl, ACL_TYPE_ACCESS);
270 		posix_acl_release(acl);
271 	} else {
272 		inode->i_acl = NULL;
273 	}
274 	return error;
275 }
276