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 */
19static struct posix_acl *
20ext2_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
83fail:
84	posix_acl_release(acl);
85	return ERR_PTR(-EINVAL);
86}
87
88/*
89 * Convert from in-memory to filesystem representation.
90 */
91static void *
92ext2_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
135fail:
136	kfree(ext_acl);
137	return ERR_PTR(-EINVAL);
138}
139
140/*
141 * inode->i_mutex: don't care
142 */
143struct posix_acl *
144ext2_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
182static int
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 */
221int
222ext2_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
223	     struct posix_acl *acl, int type)
224{
225	int error;
226	int update_mode = 0;
227	struct inode *inode = d_inode(dentry);
228	umode_t mode = inode->i_mode;
229
230	if (type == ACL_TYPE_ACCESS && acl) {
231		error = posix_acl_update_mode(&nop_mnt_idmap, inode, &mode,
232					      &acl);
233		if (error)
234			return error;
235		update_mode = 1;
236	}
237	error = __ext2_set_acl(inode, acl, type);
238	if (!error && update_mode) {
239		inode->i_mode = mode;
240		inode_set_ctime_current(inode);
241		mark_inode_dirty(inode);
242	}
243	return error;
244}
245
246/*
247 * Initialize the ACLs of a new inode. Called from ext2_new_inode.
248 *
249 * dir->i_mutex: down
250 * inode->i_mutex: up (access to inode is still exclusive)
251 */
252int
253ext2_init_acl(struct inode *inode, struct inode *dir)
254{
255	struct posix_acl *default_acl, *acl;
256	int error;
257
258	error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
259	if (error)
260		return error;
261
262	if (default_acl) {
263		error = __ext2_set_acl(inode, default_acl, ACL_TYPE_DEFAULT);
264		posix_acl_release(default_acl);
265	} else {
266		inode->i_default_acl = NULL;
267	}
268	if (acl) {
269		if (!error)
270			error = __ext2_set_acl(inode, acl, ACL_TYPE_ACCESS);
271		posix_acl_release(acl);
272	} else {
273		inode->i_acl = NULL;
274	}
275	return error;
276}
277