xref: /openbmc/linux/fs/xfs/xfs_acl.c (revision 4bb1eb3c)
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_attr.h"
14 #include "xfs_trace.h"
15 #include "xfs_error.h"
16 #include "xfs_acl.h"
17 #include "xfs_da_format.h"
18 #include "xfs_da_btree.h"
19 
20 #include <linux/posix_acl_xattr.h>
21 
22 /*
23  * Locking scheme:
24  *  - all ACL updates are protected by inode->i_mutex, which is taken before
25  *    calling into this file.
26  */
27 
28 STATIC struct posix_acl *
29 xfs_acl_from_disk(
30 	struct xfs_mount	*mp,
31 	const struct xfs_acl	*aclp,
32 	int			len,
33 	int			max_entries)
34 {
35 	struct posix_acl_entry *acl_e;
36 	struct posix_acl *acl;
37 	const struct xfs_acl_entry *ace;
38 	unsigned int count, i;
39 
40 	if (len < sizeof(*aclp)) {
41 		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, aclp,
42 				len);
43 		return ERR_PTR(-EFSCORRUPTED);
44 	}
45 
46 	count = be32_to_cpu(aclp->acl_cnt);
47 	if (count > max_entries || XFS_ACL_SIZE(count) != len) {
48 		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, aclp,
49 				len);
50 		return ERR_PTR(-EFSCORRUPTED);
51 	}
52 
53 	acl = posix_acl_alloc(count, GFP_KERNEL);
54 	if (!acl)
55 		return ERR_PTR(-ENOMEM);
56 
57 	for (i = 0; i < count; i++) {
58 		acl_e = &acl->a_entries[i];
59 		ace = &aclp->acl_entry[i];
60 
61 		/*
62 		 * The tag is 32 bits on disk and 16 bits in core.
63 		 *
64 		 * Because every access to it goes through the core
65 		 * format first this is not a problem.
66 		 */
67 		acl_e->e_tag = be32_to_cpu(ace->ae_tag);
68 		acl_e->e_perm = be16_to_cpu(ace->ae_perm);
69 
70 		switch (acl_e->e_tag) {
71 		case ACL_USER:
72 			acl_e->e_uid = make_kuid(&init_user_ns,
73 						 be32_to_cpu(ace->ae_id));
74 			break;
75 		case ACL_GROUP:
76 			acl_e->e_gid = make_kgid(&init_user_ns,
77 						 be32_to_cpu(ace->ae_id));
78 			break;
79 		case ACL_USER_OBJ:
80 		case ACL_GROUP_OBJ:
81 		case ACL_MASK:
82 		case ACL_OTHER:
83 			break;
84 		default:
85 			goto fail;
86 		}
87 	}
88 	return acl;
89 
90 fail:
91 	posix_acl_release(acl);
92 	return ERR_PTR(-EINVAL);
93 }
94 
95 STATIC void
96 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
97 {
98 	const struct posix_acl_entry *acl_e;
99 	struct xfs_acl_entry *ace;
100 	int i;
101 
102 	aclp->acl_cnt = cpu_to_be32(acl->a_count);
103 	for (i = 0; i < acl->a_count; i++) {
104 		ace = &aclp->acl_entry[i];
105 		acl_e = &acl->a_entries[i];
106 
107 		ace->ae_tag = cpu_to_be32(acl_e->e_tag);
108 		switch (acl_e->e_tag) {
109 		case ACL_USER:
110 			ace->ae_id = cpu_to_be32(
111 					from_kuid(&init_user_ns, acl_e->e_uid));
112 			break;
113 		case ACL_GROUP:
114 			ace->ae_id = cpu_to_be32(
115 					from_kgid(&init_user_ns, acl_e->e_gid));
116 			break;
117 		default:
118 			ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
119 			break;
120 		}
121 
122 		ace->ae_perm = cpu_to_be16(acl_e->e_perm);
123 	}
124 }
125 
126 struct posix_acl *
127 xfs_get_acl(struct inode *inode, int type)
128 {
129 	struct xfs_inode	*ip = XFS_I(inode);
130 	struct xfs_mount	*mp = ip->i_mount;
131 	struct posix_acl	*acl = NULL;
132 	struct xfs_da_args	args = {
133 		.dp		= ip,
134 		.attr_filter	= XFS_ATTR_ROOT,
135 		.valuelen	= XFS_ACL_MAX_SIZE(mp),
136 	};
137 	int			error;
138 
139 	trace_xfs_get_acl(ip);
140 
141 	switch (type) {
142 	case ACL_TYPE_ACCESS:
143 		args.name = SGI_ACL_FILE;
144 		break;
145 	case ACL_TYPE_DEFAULT:
146 		args.name = SGI_ACL_DEFAULT;
147 		break;
148 	default:
149 		BUG();
150 	}
151 	args.namelen = strlen(args.name);
152 
153 	/*
154 	 * If the attribute doesn't exist make sure we have a negative cache
155 	 * entry, for any other error assume it is transient.
156 	 */
157 	error = xfs_attr_get(&args);
158 	if (!error) {
159 		acl = xfs_acl_from_disk(mp, args.value, args.valuelen,
160 					XFS_ACL_MAX_ENTRIES(mp));
161 	} else if (error != -ENOATTR) {
162 		acl = ERR_PTR(error);
163 	}
164 
165 	kmem_free(args.value);
166 	return acl;
167 }
168 
169 int
170 __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
171 {
172 	struct xfs_inode	*ip = XFS_I(inode);
173 	struct xfs_da_args	args = {
174 		.dp		= ip,
175 		.attr_filter	= XFS_ATTR_ROOT,
176 	};
177 	int			error;
178 
179 	switch (type) {
180 	case ACL_TYPE_ACCESS:
181 		args.name = SGI_ACL_FILE;
182 		break;
183 	case ACL_TYPE_DEFAULT:
184 		if (!S_ISDIR(inode->i_mode))
185 			return acl ? -EACCES : 0;
186 		args.name = SGI_ACL_DEFAULT;
187 		break;
188 	default:
189 		return -EINVAL;
190 	}
191 	args.namelen = strlen(args.name);
192 
193 	if (acl) {
194 		args.valuelen = XFS_ACL_SIZE(acl->a_count);
195 		args.value = kmem_zalloc_large(args.valuelen, 0);
196 		if (!args.value)
197 			return -ENOMEM;
198 		xfs_acl_to_disk(args.value, acl);
199 	}
200 
201 	error = xfs_attr_set(&args);
202 	kmem_free(args.value);
203 
204 	/*
205 	 * If the attribute didn't exist to start with that's fine.
206 	 */
207 	if (!acl && error == -ENOATTR)
208 		error = 0;
209 	if (!error)
210 		set_cached_acl(inode, type, acl);
211 	return error;
212 }
213 
214 static int
215 xfs_set_mode(struct inode *inode, umode_t mode)
216 {
217 	int error = 0;
218 
219 	if (mode != inode->i_mode) {
220 		struct iattr iattr;
221 
222 		iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
223 		iattr.ia_mode = mode;
224 		iattr.ia_ctime = current_time(inode);
225 
226 		error = xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
227 	}
228 
229 	return error;
230 }
231 
232 int
233 xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
234 {
235 	umode_t mode;
236 	bool set_mode = false;
237 	int error = 0;
238 
239 	if (!acl)
240 		goto set_acl;
241 
242 	error = -E2BIG;
243 	if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
244 		return error;
245 
246 	if (type == ACL_TYPE_ACCESS) {
247 		error = posix_acl_update_mode(inode, &mode, &acl);
248 		if (error)
249 			return error;
250 		set_mode = true;
251 	}
252 
253  set_acl:
254 	error =  __xfs_set_acl(inode, acl, type);
255 	if (error)
256 		return error;
257 
258 	/*
259 	 * We set the mode after successfully updating the ACL xattr because the
260 	 * xattr update can fail at ENOSPC and we don't want to change the mode
261 	 * if the ACL update hasn't been applied.
262 	 */
263 	if (set_mode)
264 		error = xfs_set_mode(inode, mode);
265 
266 	return error;
267 }
268 
269 /*
270  * Invalidate any cached ACLs if the user has bypassed the ACL interface.
271  * We don't validate the content whatsoever so it is caller responsibility to
272  * provide data in valid format and ensure i_mode is consistent.
273  */
274 void
275 xfs_forget_acl(
276 	struct inode		*inode,
277 	const char		*name)
278 {
279 	if (!strcmp(name, SGI_ACL_FILE))
280 		forget_cached_acl(inode, ACL_TYPE_ACCESS);
281 	else if (!strcmp(name, SGI_ACL_DEFAULT))
282 		forget_cached_acl(inode, ACL_TYPE_DEFAULT);
283 }
284