xref: /openbmc/linux/fs/xfs/xfs_acl.c (revision f220d3eb)
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_format.h"
8 #include "xfs_log_format.h"
9 #include "xfs_trans_resv.h"
10 #include "xfs_mount.h"
11 #include "xfs_inode.h"
12 #include "xfs_acl.h"
13 #include "xfs_attr.h"
14 #include "xfs_trace.h"
15 #include <linux/slab.h>
16 #include <linux/xattr.h>
17 #include <linux/posix_acl_xattr.h>
18 
19 
20 /*
21  * Locking scheme:
22  *  - all ACL updates are protected by inode->i_mutex, which is taken before
23  *    calling into this file.
24  */
25 
26 STATIC struct posix_acl *
27 xfs_acl_from_disk(
28 	const struct xfs_acl	*aclp,
29 	int			len,
30 	int			max_entries)
31 {
32 	struct posix_acl_entry *acl_e;
33 	struct posix_acl *acl;
34 	const struct xfs_acl_entry *ace;
35 	unsigned int count, i;
36 
37 	if (len < sizeof(*aclp))
38 		return ERR_PTR(-EFSCORRUPTED);
39 	count = be32_to_cpu(aclp->acl_cnt);
40 	if (count > max_entries || XFS_ACL_SIZE(count) != len)
41 		return ERR_PTR(-EFSCORRUPTED);
42 
43 	acl = posix_acl_alloc(count, GFP_KERNEL);
44 	if (!acl)
45 		return ERR_PTR(-ENOMEM);
46 
47 	for (i = 0; i < count; i++) {
48 		acl_e = &acl->a_entries[i];
49 		ace = &aclp->acl_entry[i];
50 
51 		/*
52 		 * The tag is 32 bits on disk and 16 bits in core.
53 		 *
54 		 * Because every access to it goes through the core
55 		 * format first this is not a problem.
56 		 */
57 		acl_e->e_tag = be32_to_cpu(ace->ae_tag);
58 		acl_e->e_perm = be16_to_cpu(ace->ae_perm);
59 
60 		switch (acl_e->e_tag) {
61 		case ACL_USER:
62 			acl_e->e_uid = xfs_uid_to_kuid(be32_to_cpu(ace->ae_id));
63 			break;
64 		case ACL_GROUP:
65 			acl_e->e_gid = xfs_gid_to_kgid(be32_to_cpu(ace->ae_id));
66 			break;
67 		case ACL_USER_OBJ:
68 		case ACL_GROUP_OBJ:
69 		case ACL_MASK:
70 		case ACL_OTHER:
71 			break;
72 		default:
73 			goto fail;
74 		}
75 	}
76 	return acl;
77 
78 fail:
79 	posix_acl_release(acl);
80 	return ERR_PTR(-EINVAL);
81 }
82 
83 STATIC void
84 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
85 {
86 	const struct posix_acl_entry *acl_e;
87 	struct xfs_acl_entry *ace;
88 	int i;
89 
90 	aclp->acl_cnt = cpu_to_be32(acl->a_count);
91 	for (i = 0; i < acl->a_count; i++) {
92 		ace = &aclp->acl_entry[i];
93 		acl_e = &acl->a_entries[i];
94 
95 		ace->ae_tag = cpu_to_be32(acl_e->e_tag);
96 		switch (acl_e->e_tag) {
97 		case ACL_USER:
98 			ace->ae_id = cpu_to_be32(xfs_kuid_to_uid(acl_e->e_uid));
99 			break;
100 		case ACL_GROUP:
101 			ace->ae_id = cpu_to_be32(xfs_kgid_to_gid(acl_e->e_gid));
102 			break;
103 		default:
104 			ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
105 			break;
106 		}
107 
108 		ace->ae_perm = cpu_to_be16(acl_e->e_perm);
109 	}
110 }
111 
112 struct posix_acl *
113 xfs_get_acl(struct inode *inode, int type)
114 {
115 	struct xfs_inode *ip = XFS_I(inode);
116 	struct posix_acl *acl = NULL;
117 	struct xfs_acl *xfs_acl;
118 	unsigned char *ea_name;
119 	int error;
120 	int len;
121 
122 	trace_xfs_get_acl(ip);
123 
124 	switch (type) {
125 	case ACL_TYPE_ACCESS:
126 		ea_name = SGI_ACL_FILE;
127 		break;
128 	case ACL_TYPE_DEFAULT:
129 		ea_name = SGI_ACL_DEFAULT;
130 		break;
131 	default:
132 		BUG();
133 	}
134 
135 	/*
136 	 * If we have a cached ACLs value just return it, not need to
137 	 * go out to the disk.
138 	 */
139 	len = XFS_ACL_MAX_SIZE(ip->i_mount);
140 	xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
141 	if (!xfs_acl)
142 		return ERR_PTR(-ENOMEM);
143 
144 	error = xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
145 							&len, ATTR_ROOT);
146 	if (error) {
147 		/*
148 		 * If the attribute doesn't exist make sure we have a negative
149 		 * cache entry, for any other error assume it is transient.
150 		 */
151 		if (error != -ENOATTR)
152 			acl = ERR_PTR(error);
153 	} else  {
154 		acl = xfs_acl_from_disk(xfs_acl, len,
155 					XFS_ACL_MAX_ENTRIES(ip->i_mount));
156 	}
157 	kmem_free(xfs_acl);
158 	return acl;
159 }
160 
161 int
162 __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
163 {
164 	struct xfs_inode *ip = XFS_I(inode);
165 	unsigned char *ea_name;
166 	int error;
167 
168 	switch (type) {
169 	case ACL_TYPE_ACCESS:
170 		ea_name = SGI_ACL_FILE;
171 		break;
172 	case ACL_TYPE_DEFAULT:
173 		if (!S_ISDIR(inode->i_mode))
174 			return acl ? -EACCES : 0;
175 		ea_name = SGI_ACL_DEFAULT;
176 		break;
177 	default:
178 		return -EINVAL;
179 	}
180 
181 	if (acl) {
182 		struct xfs_acl *xfs_acl;
183 		int len = XFS_ACL_MAX_SIZE(ip->i_mount);
184 
185 		xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
186 		if (!xfs_acl)
187 			return -ENOMEM;
188 
189 		xfs_acl_to_disk(xfs_acl, acl);
190 
191 		/* subtract away the unused acl entries */
192 		len -= sizeof(struct xfs_acl_entry) *
193 			 (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
194 
195 		error = xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
196 				len, ATTR_ROOT);
197 
198 		kmem_free(xfs_acl);
199 	} else {
200 		/*
201 		 * A NULL ACL argument means we want to remove the ACL.
202 		 */
203 		error = xfs_attr_remove(ip, ea_name, ATTR_ROOT);
204 
205 		/*
206 		 * If the attribute didn't exist to start with that's fine.
207 		 */
208 		if (error == -ENOATTR)
209 			error = 0;
210 	}
211 
212 	if (!error)
213 		set_cached_acl(inode, type, acl);
214 	return error;
215 }
216 
217 static int
218 xfs_set_mode(struct inode *inode, umode_t mode)
219 {
220 	int error = 0;
221 
222 	if (mode != inode->i_mode) {
223 		struct iattr iattr;
224 
225 		iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
226 		iattr.ia_mode = mode;
227 		iattr.ia_ctime = current_time(inode);
228 
229 		error = xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
230 	}
231 
232 	return error;
233 }
234 
235 int
236 xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
237 {
238 	umode_t mode;
239 	bool set_mode = false;
240 	int error = 0;
241 
242 	if (!acl)
243 		goto set_acl;
244 
245 	error = -E2BIG;
246 	if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
247 		return error;
248 
249 	if (type == ACL_TYPE_ACCESS) {
250 		error = posix_acl_update_mode(inode, &mode, &acl);
251 		if (error)
252 			return error;
253 		set_mode = true;
254 	}
255 
256  set_acl:
257 	error =  __xfs_set_acl(inode, acl, type);
258 	if (error)
259 		return error;
260 
261 	/*
262 	 * We set the mode after successfully updating the ACL xattr because the
263 	 * xattr update can fail at ENOSPC and we don't want to change the mode
264 	 * if the ACL update hasn't been applied.
265 	 */
266 	if (set_mode)
267 		error = xfs_set_mode(inode, mode);
268 
269 	return error;
270 }
271