1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * linux/fs/ext4/acl.c
4  *
5  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
6  */
7 
8 #include <linux/quotaops.h>
9 #include "ext4_jbd2.h"
10 #include "ext4.h"
11 #include "xattr.h"
12 #include "acl.h"
13 
14 /*
15  * Convert from filesystem to in-memory representation.
16  */
17 static struct posix_acl *
ext4_acl_from_disk(const void * value,size_t size)18 ext4_acl_from_disk(const void *value, size_t size)
19 {
20 	const char *end = (char *)value + size;
21 	int n, count;
22 	struct posix_acl *acl;
23 
24 	if (!value)
25 		return NULL;
26 	if (size < sizeof(ext4_acl_header))
27 		 return ERR_PTR(-EINVAL);
28 	if (((ext4_acl_header *)value)->a_version !=
29 	    cpu_to_le32(EXT4_ACL_VERSION))
30 		return ERR_PTR(-EINVAL);
31 	value = (char *)value + sizeof(ext4_acl_header);
32 	count = ext4_acl_count(size);
33 	if (count < 0)
34 		return ERR_PTR(-EINVAL);
35 	if (count == 0)
36 		return NULL;
37 	acl = posix_acl_alloc(count, GFP_NOFS);
38 	if (!acl)
39 		return ERR_PTR(-ENOMEM);
40 	for (n = 0; n < count; n++) {
41 		ext4_acl_entry *entry =
42 			(ext4_acl_entry *)value;
43 		if ((char *)value + sizeof(ext4_acl_entry_short) > end)
44 			goto fail;
45 		acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
46 		acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
47 
48 		switch (acl->a_entries[n].e_tag) {
49 		case ACL_USER_OBJ:
50 		case ACL_GROUP_OBJ:
51 		case ACL_MASK:
52 		case ACL_OTHER:
53 			value = (char *)value +
54 				sizeof(ext4_acl_entry_short);
55 			break;
56 
57 		case ACL_USER:
58 			value = (char *)value + sizeof(ext4_acl_entry);
59 			if ((char *)value > end)
60 				goto fail;
61 			acl->a_entries[n].e_uid =
62 				make_kuid(&init_user_ns,
63 					  le32_to_cpu(entry->e_id));
64 			break;
65 		case ACL_GROUP:
66 			value = (char *)value + sizeof(ext4_acl_entry);
67 			if ((char *)value > end)
68 				goto fail;
69 			acl->a_entries[n].e_gid =
70 				make_kgid(&init_user_ns,
71 					  le32_to_cpu(entry->e_id));
72 			break;
73 
74 		default:
75 			goto fail;
76 		}
77 	}
78 	if (value != end)
79 		goto fail;
80 	return acl;
81 
82 fail:
83 	posix_acl_release(acl);
84 	return ERR_PTR(-EINVAL);
85 }
86 
87 /*
88  * Convert from in-memory to filesystem representation.
89  */
90 static void *
ext4_acl_to_disk(const struct posix_acl * acl,size_t * size)91 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
92 {
93 	ext4_acl_header *ext_acl;
94 	char *e;
95 	size_t n;
96 
97 	*size = ext4_acl_size(acl->a_count);
98 	ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
99 			sizeof(ext4_acl_entry), GFP_NOFS);
100 	if (!ext_acl)
101 		return ERR_PTR(-ENOMEM);
102 	ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
103 	e = (char *)ext_acl + sizeof(ext4_acl_header);
104 	for (n = 0; n < acl->a_count; n++) {
105 		const struct posix_acl_entry *acl_e = &acl->a_entries[n];
106 		ext4_acl_entry *entry = (ext4_acl_entry *)e;
107 		entry->e_tag  = cpu_to_le16(acl_e->e_tag);
108 		entry->e_perm = cpu_to_le16(acl_e->e_perm);
109 		switch (acl_e->e_tag) {
110 		case ACL_USER:
111 			entry->e_id = cpu_to_le32(
112 				from_kuid(&init_user_ns, acl_e->e_uid));
113 			e += sizeof(ext4_acl_entry);
114 			break;
115 		case ACL_GROUP:
116 			entry->e_id = cpu_to_le32(
117 				from_kgid(&init_user_ns, acl_e->e_gid));
118 			e += sizeof(ext4_acl_entry);
119 			break;
120 
121 		case ACL_USER_OBJ:
122 		case ACL_GROUP_OBJ:
123 		case ACL_MASK:
124 		case ACL_OTHER:
125 			e += sizeof(ext4_acl_entry_short);
126 			break;
127 
128 		default:
129 			goto fail;
130 		}
131 	}
132 	return (char *)ext_acl;
133 
134 fail:
135 	kfree(ext_acl);
136 	return ERR_PTR(-EINVAL);
137 }
138 
139 /*
140  * Inode operation get_posix_acl().
141  *
142  * inode->i_rwsem: don't care
143  */
144 struct posix_acl *
ext4_get_acl(struct inode * inode,int type,bool rcu)145 ext4_get_acl(struct inode *inode, int type, bool rcu)
146 {
147 	int name_index;
148 	char *value = NULL;
149 	struct posix_acl *acl;
150 	int retval;
151 
152 	if (rcu)
153 		return ERR_PTR(-ECHILD);
154 
155 	switch (type) {
156 	case ACL_TYPE_ACCESS:
157 		name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
158 		break;
159 	case ACL_TYPE_DEFAULT:
160 		name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
161 		break;
162 	default:
163 		BUG();
164 	}
165 	retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
166 	if (retval > 0) {
167 		value = kmalloc(retval, GFP_NOFS);
168 		if (!value)
169 			return ERR_PTR(-ENOMEM);
170 		retval = ext4_xattr_get(inode, name_index, "", value, retval);
171 	}
172 	if (retval > 0)
173 		acl = ext4_acl_from_disk(value, retval);
174 	else if (retval == -ENODATA || retval == -ENOSYS)
175 		acl = NULL;
176 	else
177 		acl = ERR_PTR(retval);
178 	kfree(value);
179 
180 	return acl;
181 }
182 
183 /*
184  * Set the access or default ACL of an inode.
185  *
186  * inode->i_rwsem: down unless called from ext4_new_inode
187  */
188 static int
__ext4_set_acl(handle_t * handle,struct inode * inode,int type,struct posix_acl * acl,int xattr_flags)189 __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
190 	     struct posix_acl *acl, int xattr_flags)
191 {
192 	int name_index;
193 	void *value = NULL;
194 	size_t size = 0;
195 	int error;
196 
197 	switch (type) {
198 	case ACL_TYPE_ACCESS:
199 		name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
200 		break;
201 
202 	case ACL_TYPE_DEFAULT:
203 		name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
204 		if (!S_ISDIR(inode->i_mode))
205 			return acl ? -EACCES : 0;
206 		break;
207 
208 	default:
209 		return -EINVAL;
210 	}
211 	if (acl) {
212 		value = ext4_acl_to_disk(acl, &size);
213 		if (IS_ERR(value))
214 			return (int)PTR_ERR(value);
215 	}
216 
217 	error = ext4_xattr_set_handle(handle, inode, name_index, "",
218 				      value, size, xattr_flags);
219 
220 	kfree(value);
221 	if (!error)
222 		set_cached_acl(inode, type, acl);
223 
224 	return error;
225 }
226 
227 int
ext4_set_acl(struct user_namespace * mnt_userns,struct inode * inode,struct posix_acl * acl,int type)228 ext4_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
229 	     struct posix_acl *acl, int type)
230 {
231 	handle_t *handle;
232 	int error, credits, retries = 0;
233 	size_t acl_size = acl ? ext4_acl_size(acl->a_count) : 0;
234 	umode_t mode = inode->i_mode;
235 	int update_mode = 0;
236 
237 	error = dquot_initialize(inode);
238 	if (error)
239 		return error;
240 retry:
241 	error = ext4_xattr_set_credits(inode, acl_size, false /* is_create */,
242 				       &credits);
243 	if (error)
244 		return error;
245 
246 	handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
247 	if (IS_ERR(handle))
248 		return PTR_ERR(handle);
249 
250 	if ((type == ACL_TYPE_ACCESS) && acl) {
251 		error = posix_acl_update_mode(mnt_userns, inode, &mode, &acl);
252 		if (error)
253 			goto out_stop;
254 		if (mode != inode->i_mode)
255 			update_mode = 1;
256 	}
257 
258 	error = __ext4_set_acl(handle, inode, type, acl, 0 /* xattr_flags */);
259 	if (!error && update_mode) {
260 		inode->i_mode = mode;
261 		inode->i_ctime = current_time(inode);
262 		error = ext4_mark_inode_dirty(handle, inode);
263 	}
264 out_stop:
265 	ext4_journal_stop(handle);
266 	if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
267 		goto retry;
268 	return error;
269 }
270 
271 /*
272  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
273  *
274  * dir->i_rwsem: down
275  * inode->i_rwsem: up (access to inode is still exclusive)
276  */
277 int
ext4_init_acl(handle_t * handle,struct inode * inode,struct inode * dir)278 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
279 {
280 	struct posix_acl *default_acl, *acl;
281 	int error;
282 
283 	error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
284 	if (error)
285 		return error;
286 
287 	if (default_acl) {
288 		error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT,
289 				       default_acl, XATTR_CREATE);
290 		posix_acl_release(default_acl);
291 	} else {
292 		inode->i_default_acl = NULL;
293 	}
294 	if (acl) {
295 		if (!error)
296 			error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS,
297 					       acl, XATTR_CREATE);
298 		posix_acl_release(acl);
299 	} else {
300 		inode->i_acl = NULL;
301 	}
302 	return error;
303 }
304