1 /*
2 * fs/nfs_common/nfsacl.c
3 *
4 * Copyright (C) 2002-2003 Andreas Gruenbacher <agruen@suse.de>
5 */
6
7 /*
8 * The Solaris nfsacl protocol represents some ACLs slightly differently
9 * than POSIX 1003.1e draft 17 does (and we do):
10 *
11 * - Minimal ACLs always have an ACL_MASK entry, so they have
12 * four instead of three entries.
13 * - The ACL_MASK entry in such minimal ACLs always has the same
14 * permissions as the ACL_GROUP_OBJ entry. (In extended ACLs
15 * the ACL_MASK and ACL_GROUP_OBJ entries may differ.)
16 * - The identifier fields of the ACL_USER_OBJ and ACL_GROUP_OBJ
17 * entries contain the identifiers of the owner and owning group.
18 * (In POSIX ACLs we always set them to ACL_UNDEFINED_ID).
19 * - ACL entries in the kernel are kept sorted in ascending order
20 * of (e_tag, e_id). Solaris ACLs are unsorted.
21 */
22
23 #include <linux/module.h>
24 #include <linux/fs.h>
25 #include <linux/gfp.h>
26 #include <linux/sunrpc/xdr.h>
27 #include <linux/nfsacl.h>
28 #include <linux/nfs3.h>
29 #include <linux/sort.h>
30
31 MODULE_LICENSE("GPL");
32
33 struct nfsacl_encode_desc {
34 struct xdr_array2_desc desc;
35 unsigned int count;
36 struct posix_acl *acl;
37 int typeflag;
38 kuid_t uid;
39 kgid_t gid;
40 };
41
42 struct nfsacl_simple_acl {
43 struct posix_acl acl;
44 struct posix_acl_entry ace[4];
45 };
46
47 static int
xdr_nfsace_encode(struct xdr_array2_desc * desc,void * elem)48 xdr_nfsace_encode(struct xdr_array2_desc *desc, void *elem)
49 {
50 struct nfsacl_encode_desc *nfsacl_desc =
51 (struct nfsacl_encode_desc *) desc;
52 __be32 *p = elem;
53
54 struct posix_acl_entry *entry =
55 &nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
56
57 *p++ = htonl(entry->e_tag | nfsacl_desc->typeflag);
58 switch(entry->e_tag) {
59 case ACL_USER_OBJ:
60 *p++ = htonl(from_kuid(&init_user_ns, nfsacl_desc->uid));
61 break;
62 case ACL_GROUP_OBJ:
63 *p++ = htonl(from_kgid(&init_user_ns, nfsacl_desc->gid));
64 break;
65 case ACL_USER:
66 *p++ = htonl(from_kuid(&init_user_ns, entry->e_uid));
67 break;
68 case ACL_GROUP:
69 *p++ = htonl(from_kgid(&init_user_ns, entry->e_gid));
70 break;
71 default: /* Solaris depends on that! */
72 *p++ = 0;
73 break;
74 }
75 *p++ = htonl(entry->e_perm & S_IRWXO);
76 return 0;
77 }
78
79 /**
80 * nfsacl_encode - Encode an NFSv3 ACL
81 *
82 * @buf: destination xdr_buf to contain XDR encoded ACL
83 * @base: byte offset in xdr_buf where XDR'd ACL begins
84 * @inode: inode of file whose ACL this is
85 * @acl: posix_acl to encode
86 * @encode_entries: whether to encode ACEs as well
87 * @typeflag: ACL type: NFS_ACL_DEFAULT or zero
88 *
89 * Returns size of encoded ACL in bytes or a negative errno value.
90 */
nfsacl_encode(struct xdr_buf * buf,unsigned int base,struct inode * inode,struct posix_acl * acl,int encode_entries,int typeflag)91 int nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
92 struct posix_acl *acl, int encode_entries, int typeflag)
93 {
94 int entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
95 struct nfsacl_encode_desc nfsacl_desc = {
96 .desc = {
97 .elem_size = 12,
98 .array_len = encode_entries ? entries : 0,
99 .xcode = xdr_nfsace_encode,
100 },
101 .acl = acl,
102 .typeflag = typeflag,
103 .uid = inode->i_uid,
104 .gid = inode->i_gid,
105 };
106 struct nfsacl_simple_acl aclbuf;
107 int err;
108
109 if (entries > NFS_ACL_MAX_ENTRIES ||
110 xdr_encode_word(buf, base, entries))
111 return -EINVAL;
112 if (encode_entries && acl && acl->a_count == 3) {
113 struct posix_acl *acl2 = &aclbuf.acl;
114
115 /* Avoid the use of posix_acl_alloc(). nfsacl_encode() is
116 * invoked in contexts where a memory allocation failure is
117 * fatal. Fortunately this fake ACL is small enough to
118 * construct on the stack. */
119 posix_acl_init(acl2, 4);
120
121 /* Insert entries in canonical order: other orders seem
122 to confuse Solaris VxFS. */
123 acl2->a_entries[0] = acl->a_entries[0]; /* ACL_USER_OBJ */
124 acl2->a_entries[1] = acl->a_entries[1]; /* ACL_GROUP_OBJ */
125 acl2->a_entries[2] = acl->a_entries[1]; /* ACL_MASK */
126 acl2->a_entries[2].e_tag = ACL_MASK;
127 acl2->a_entries[3] = acl->a_entries[2]; /* ACL_OTHER */
128 nfsacl_desc.acl = acl2;
129 }
130 err = xdr_encode_array2(buf, base + 4, &nfsacl_desc.desc);
131 if (!err)
132 err = 8 + nfsacl_desc.desc.elem_size *
133 nfsacl_desc.desc.array_len;
134 return err;
135 }
136 EXPORT_SYMBOL_GPL(nfsacl_encode);
137
138 struct nfsacl_decode_desc {
139 struct xdr_array2_desc desc;
140 unsigned int count;
141 struct posix_acl *acl;
142 };
143
144 static int
xdr_nfsace_decode(struct xdr_array2_desc * desc,void * elem)145 xdr_nfsace_decode(struct xdr_array2_desc *desc, void *elem)
146 {
147 struct nfsacl_decode_desc *nfsacl_desc =
148 (struct nfsacl_decode_desc *) desc;
149 __be32 *p = elem;
150 struct posix_acl_entry *entry;
151 unsigned int id;
152
153 if (!nfsacl_desc->acl) {
154 if (desc->array_len > NFS_ACL_MAX_ENTRIES)
155 return -EINVAL;
156 nfsacl_desc->acl = posix_acl_alloc(desc->array_len, GFP_KERNEL);
157 if (!nfsacl_desc->acl)
158 return -ENOMEM;
159 nfsacl_desc->count = 0;
160 }
161
162 entry = &nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
163 entry->e_tag = ntohl(*p++) & ~NFS_ACL_DEFAULT;
164 id = ntohl(*p++);
165 entry->e_perm = ntohl(*p++);
166
167 switch(entry->e_tag) {
168 case ACL_USER:
169 entry->e_uid = make_kuid(&init_user_ns, id);
170 if (!uid_valid(entry->e_uid))
171 return -EINVAL;
172 break;
173 case ACL_GROUP:
174 entry->e_gid = make_kgid(&init_user_ns, id);
175 if (!gid_valid(entry->e_gid))
176 return -EINVAL;
177 break;
178 case ACL_USER_OBJ:
179 case ACL_GROUP_OBJ:
180 case ACL_OTHER:
181 if (entry->e_perm & ~S_IRWXO)
182 return -EINVAL;
183 break;
184 case ACL_MASK:
185 /* Solaris sometimes sets additional bits in the mask */
186 entry->e_perm &= S_IRWXO;
187 break;
188 default:
189 return -EINVAL;
190 }
191
192 return 0;
193 }
194
195 static int
cmp_acl_entry(const void * x,const void * y)196 cmp_acl_entry(const void *x, const void *y)
197 {
198 const struct posix_acl_entry *a = x, *b = y;
199
200 if (a->e_tag != b->e_tag)
201 return a->e_tag - b->e_tag;
202 else if ((a->e_tag == ACL_USER) && uid_gt(a->e_uid, b->e_uid))
203 return 1;
204 else if ((a->e_tag == ACL_USER) && uid_lt(a->e_uid, b->e_uid))
205 return -1;
206 else if ((a->e_tag == ACL_GROUP) && gid_gt(a->e_gid, b->e_gid))
207 return 1;
208 else if ((a->e_tag == ACL_GROUP) && gid_lt(a->e_gid, b->e_gid))
209 return -1;
210 else
211 return 0;
212 }
213
214 /*
215 * Convert from a Solaris ACL to a POSIX 1003.1e draft 17 ACL.
216 */
217 static int
posix_acl_from_nfsacl(struct posix_acl * acl)218 posix_acl_from_nfsacl(struct posix_acl *acl)
219 {
220 struct posix_acl_entry *pa, *pe,
221 *group_obj = NULL, *mask = NULL;
222
223 if (!acl)
224 return 0;
225
226 sort(acl->a_entries, acl->a_count, sizeof(struct posix_acl_entry),
227 cmp_acl_entry, NULL);
228
229 /* Find the ACL_GROUP_OBJ and ACL_MASK entries. */
230 FOREACH_ACL_ENTRY(pa, acl, pe) {
231 switch(pa->e_tag) {
232 case ACL_USER_OBJ:
233 break;
234 case ACL_GROUP_OBJ:
235 group_obj = pa;
236 break;
237 case ACL_MASK:
238 mask = pa;
239 /* fall through */
240 case ACL_OTHER:
241 break;
242 }
243 }
244 if (acl->a_count == 4 && group_obj && mask &&
245 mask->e_perm == group_obj->e_perm) {
246 /* remove bogus ACL_MASK entry */
247 memmove(mask, mask+1, (3 - (mask - acl->a_entries)) *
248 sizeof(struct posix_acl_entry));
249 acl->a_count = 3;
250 }
251 return 0;
252 }
253
254 /**
255 * nfsacl_decode - Decode an NFSv3 ACL
256 *
257 * @buf: xdr_buf containing XDR'd ACL data to decode
258 * @base: byte offset in xdr_buf where XDR'd ACL begins
259 * @aclcnt: count of ACEs in decoded posix_acl
260 * @pacl: buffer in which to place decoded posix_acl
261 *
262 * Returns the length of the decoded ACL in bytes, or a negative errno value.
263 */
nfsacl_decode(struct xdr_buf * buf,unsigned int base,unsigned int * aclcnt,struct posix_acl ** pacl)264 int nfsacl_decode(struct xdr_buf *buf, unsigned int base, unsigned int *aclcnt,
265 struct posix_acl **pacl)
266 {
267 struct nfsacl_decode_desc nfsacl_desc = {
268 .desc = {
269 .elem_size = 12,
270 .xcode = pacl ? xdr_nfsace_decode : NULL,
271 },
272 };
273 u32 entries;
274 int err;
275
276 if (xdr_decode_word(buf, base, &entries) ||
277 entries > NFS_ACL_MAX_ENTRIES)
278 return -EINVAL;
279 nfsacl_desc.desc.array_maxlen = entries;
280 err = xdr_decode_array2(buf, base + 4, &nfsacl_desc.desc);
281 if (err)
282 return err;
283 if (pacl) {
284 if (entries != nfsacl_desc.desc.array_len ||
285 posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
286 posix_acl_release(nfsacl_desc.acl);
287 return -EINVAL;
288 }
289 *pacl = nfsacl_desc.acl;
290 }
291 if (aclcnt)
292 *aclcnt = entries;
293 return 8 + nfsacl_desc.desc.elem_size *
294 nfsacl_desc.desc.array_len;
295 }
296 EXPORT_SYMBOL_GPL(nfsacl_decode);
297