xref: /openbmc/linux/fs/xfs/xfs_acl.c (revision a0a415e3)
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 
30 STATIC struct posix_acl *
xfs_acl_from_disk(struct xfs_mount * mp,const struct xfs_acl * aclp,int len,int max_entries)31 xfs_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 
92 fail:
93 	posix_acl_release(acl);
94 	return ERR_PTR(-EINVAL);
95 }
96 
97 STATIC void
xfs_acl_to_disk(struct xfs_acl * aclp,const struct posix_acl * acl)98 xfs_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 
128 struct posix_acl *
xfs_get_acl(struct inode * inode,int type,bool rcu)129 xfs_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 	kmem_free(args.value);
171 	return acl;
172 }
173 
174 int
__xfs_set_acl(struct inode * inode,struct posix_acl * acl,int type)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 	kmem_free(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 
219 static int
xfs_acl_set_mode(struct inode * inode,umode_t mode)220 xfs_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 
244 int
xfs_set_acl(struct mnt_idmap * idmap,struct dentry * dentry,struct posix_acl * acl,int type)245 xfs_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  */
284 void
xfs_forget_acl(struct inode * inode,const char * name)285 xfs_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