1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2008, Christoph Hellwig
4 * All Rights Reserved.
5 */
6#include "xfs.h"
7#include "xfs_shared.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_inode.h"
13#include "xfs_da_format.h"
14#include "xfs_da_btree.h"
15#include "xfs_attr.h"
16#include "xfs_trace.h"
17#include "xfs_error.h"
18#include "xfs_acl.h"
19#include "xfs_trans.h"
20#include "xfs_xattr.h"
21
22#include <linux/posix_acl_xattr.h>
23
24/*
25 * Locking scheme:
26 *  - all ACL updates are protected by inode->i_mutex, which is taken before
27 *    calling into this file.
28 */
29
30STATIC struct posix_acl *
31xfs_acl_from_disk(
32	struct xfs_mount	*mp,
33	const struct xfs_acl	*aclp,
34	int			len,
35	int			max_entries)
36{
37	struct posix_acl_entry *acl_e;
38	struct posix_acl *acl;
39	const struct xfs_acl_entry *ace;
40	unsigned int count, i;
41
42	if (len < sizeof(*aclp)) {
43		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, aclp,
44				len);
45		return ERR_PTR(-EFSCORRUPTED);
46	}
47
48	count = be32_to_cpu(aclp->acl_cnt);
49	if (count > max_entries || XFS_ACL_SIZE(count) != len) {
50		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, aclp,
51				len);
52		return ERR_PTR(-EFSCORRUPTED);
53	}
54
55	acl = posix_acl_alloc(count, GFP_KERNEL);
56	if (!acl)
57		return ERR_PTR(-ENOMEM);
58
59	for (i = 0; i < count; i++) {
60		acl_e = &acl->a_entries[i];
61		ace = &aclp->acl_entry[i];
62
63		/*
64		 * The tag is 32 bits on disk and 16 bits in core.
65		 *
66		 * Because every access to it goes through the core
67		 * format first this is not a problem.
68		 */
69		acl_e->e_tag = be32_to_cpu(ace->ae_tag);
70		acl_e->e_perm = be16_to_cpu(ace->ae_perm);
71
72		switch (acl_e->e_tag) {
73		case ACL_USER:
74			acl_e->e_uid = make_kuid(&init_user_ns,
75						 be32_to_cpu(ace->ae_id));
76			break;
77		case ACL_GROUP:
78			acl_e->e_gid = make_kgid(&init_user_ns,
79						 be32_to_cpu(ace->ae_id));
80			break;
81		case ACL_USER_OBJ:
82		case ACL_GROUP_OBJ:
83		case ACL_MASK:
84		case ACL_OTHER:
85			break;
86		default:
87			goto fail;
88		}
89	}
90	return acl;
91
92fail:
93	posix_acl_release(acl);
94	return ERR_PTR(-EINVAL);
95}
96
97STATIC void
98xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
99{
100	const struct posix_acl_entry *acl_e;
101	struct xfs_acl_entry *ace;
102	int i;
103
104	aclp->acl_cnt = cpu_to_be32(acl->a_count);
105	for (i = 0; i < acl->a_count; i++) {
106		ace = &aclp->acl_entry[i];
107		acl_e = &acl->a_entries[i];
108
109		ace->ae_tag = cpu_to_be32(acl_e->e_tag);
110		switch (acl_e->e_tag) {
111		case ACL_USER:
112			ace->ae_id = cpu_to_be32(
113					from_kuid(&init_user_ns, acl_e->e_uid));
114			break;
115		case ACL_GROUP:
116			ace->ae_id = cpu_to_be32(
117					from_kgid(&init_user_ns, acl_e->e_gid));
118			break;
119		default:
120			ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
121			break;
122		}
123
124		ace->ae_perm = cpu_to_be16(acl_e->e_perm);
125	}
126}
127
128struct posix_acl *
129xfs_get_acl(struct inode *inode, int type, bool rcu)
130{
131	struct xfs_inode	*ip = XFS_I(inode);
132	struct xfs_mount	*mp = ip->i_mount;
133	struct posix_acl	*acl = NULL;
134	struct xfs_da_args	args = {
135		.dp		= ip,
136		.attr_filter	= XFS_ATTR_ROOT,
137		.valuelen	= XFS_ACL_MAX_SIZE(mp),
138	};
139	int			error;
140
141	if (rcu)
142		return ERR_PTR(-ECHILD);
143
144	trace_xfs_get_acl(ip);
145
146	switch (type) {
147	case ACL_TYPE_ACCESS:
148		args.name = SGI_ACL_FILE;
149		break;
150	case ACL_TYPE_DEFAULT:
151		args.name = SGI_ACL_DEFAULT;
152		break;
153	default:
154		BUG();
155	}
156	args.namelen = strlen(args.name);
157
158	/*
159	 * If the attribute doesn't exist make sure we have a negative cache
160	 * entry, for any other error assume it is transient.
161	 */
162	error = xfs_attr_get(&args);
163	if (!error) {
164		acl = xfs_acl_from_disk(mp, args.value, args.valuelen,
165					XFS_ACL_MAX_ENTRIES(mp));
166	} else if (error != -ENOATTR) {
167		acl = ERR_PTR(error);
168	}
169
170	kvfree(args.value);
171	return acl;
172}
173
174int
175__xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
176{
177	struct xfs_inode	*ip = XFS_I(inode);
178	struct xfs_da_args	args = {
179		.dp		= ip,
180		.attr_filter	= XFS_ATTR_ROOT,
181	};
182	int			error;
183
184	switch (type) {
185	case ACL_TYPE_ACCESS:
186		args.name = SGI_ACL_FILE;
187		break;
188	case ACL_TYPE_DEFAULT:
189		if (!S_ISDIR(inode->i_mode))
190			return acl ? -EACCES : 0;
191		args.name = SGI_ACL_DEFAULT;
192		break;
193	default:
194		return -EINVAL;
195	}
196	args.namelen = strlen(args.name);
197
198	if (acl) {
199		args.valuelen = XFS_ACL_SIZE(acl->a_count);
200		args.value = kvzalloc(args.valuelen, GFP_KERNEL);
201		if (!args.value)
202			return -ENOMEM;
203		xfs_acl_to_disk(args.value, acl);
204	}
205
206	error = xfs_attr_change(&args);
207	kvfree(args.value);
208
209	/*
210	 * If the attribute didn't exist to start with that's fine.
211	 */
212	if (!acl && error == -ENOATTR)
213		error = 0;
214	if (!error)
215		set_cached_acl(inode, type, acl);
216	return error;
217}
218
219static int
220xfs_acl_set_mode(
221	struct inode		*inode,
222	umode_t			mode)
223{
224	struct xfs_inode	*ip = XFS_I(inode);
225	struct xfs_mount	*mp = ip->i_mount;
226	struct xfs_trans	*tp;
227	int			error;
228
229	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
230	if (error)
231		return error;
232
233	xfs_ilock(ip, XFS_ILOCK_EXCL);
234	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
235	inode->i_mode = mode;
236	inode_set_ctime_current(inode);
237	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
238
239	if (xfs_has_wsync(mp))
240		xfs_trans_set_sync(tp);
241	return xfs_trans_commit(tp);
242}
243
244int
245xfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
246	    struct posix_acl *acl, int type)
247{
248	umode_t mode;
249	bool set_mode = false;
250	int error = 0;
251	struct inode *inode = d_inode(dentry);
252
253	if (!acl)
254		goto set_acl;
255
256	error = -E2BIG;
257	if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
258		return error;
259
260	if (type == ACL_TYPE_ACCESS) {
261		error = posix_acl_update_mode(idmap, inode, &mode, &acl);
262		if (error)
263			return error;
264		set_mode = true;
265	}
266
267 set_acl:
268	/*
269	 * We set the mode after successfully updating the ACL xattr because the
270	 * xattr update can fail at ENOSPC and we don't want to change the mode
271	 * if the ACL update hasn't been applied.
272	 */
273	error =  __xfs_set_acl(inode, acl, type);
274	if (!error && set_mode && mode != inode->i_mode)
275		error = xfs_acl_set_mode(inode, mode);
276	return error;
277}
278
279/*
280 * Invalidate any cached ACLs if the user has bypassed the ACL interface.
281 * We don't validate the content whatsoever so it is caller responsibility to
282 * provide data in valid format and ensure i_mode is consistent.
283 */
284void
285xfs_forget_acl(
286	struct inode		*inode,
287	const char		*name)
288{
289	if (!strcmp(name, SGI_ACL_FILE))
290		forget_cached_acl(inode, ACL_TYPE_ACCESS);
291	else if (!strcmp(name, SGI_ACL_DEFAULT))
292		forget_cached_acl(inode, ACL_TYPE_DEFAULT);
293}
294