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 EXPORT_SYMBOL_GPL(nfsacl_encode);
34 EXPORT_SYMBOL_GPL(nfsacl_decode);
35
36 struct nfsacl_encode_desc {
37 struct xdr_array2_desc desc;
38 unsigned int count;
39 struct posix_acl *acl;
40 int typeflag;
41 uid_t uid;
42 gid_t gid;
43 };
44
45 struct nfsacl_simple_acl {
46 struct posix_acl acl;
47 struct posix_acl_entry ace[4];
48 };
49
50 static int
xdr_nfsace_encode(struct xdr_array2_desc * desc,void * elem)51 xdr_nfsace_encode(struct xdr_array2_desc *desc, void *elem)
52 {
53 struct nfsacl_encode_desc *nfsacl_desc =
54 (struct nfsacl_encode_desc *) desc;
55 __be32 *p = elem;
56
57 struct posix_acl_entry *entry =
58 &nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
59
60 *p++ = htonl(entry->e_tag | nfsacl_desc->typeflag);
61 switch(entry->e_tag) {
62 case ACL_USER_OBJ:
63 *p++ = htonl(nfsacl_desc->uid);
64 break;
65 case ACL_GROUP_OBJ:
66 *p++ = htonl(nfsacl_desc->gid);
67 break;
68 case ACL_USER:
69 case ACL_GROUP:
70 *p++ = htonl(entry->e_id);
71 break;
72 default: /* Solaris depends on that! */
73 *p++ = 0;
74 break;
75 }
76 *p++ = htonl(entry->e_perm & S_IRWXO);
77 return 0;
78 }
79
80 /**
81 * nfsacl_encode - Encode an NFSv3 ACL
82 *
83 * @buf: destination xdr_buf to contain XDR encoded ACL
84 * @base: byte offset in xdr_buf where XDR'd ACL begins
85 * @inode: inode of file whose ACL this is
86 * @acl: posix_acl to encode
87 * @encode_entries: whether to encode ACEs as well
88 * @typeflag: ACL type: NFS_ACL_DEFAULT or zero
89 *
90 * Returns size of encoded ACL in bytes or a negative errno value.
91 */
nfsacl_encode(struct xdr_buf * buf,unsigned int base,struct inode * inode,struct posix_acl * acl,int encode_entries,int typeflag)92 int nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
93 struct posix_acl *acl, int encode_entries, int typeflag)
94 {
95 int entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
96 struct nfsacl_encode_desc nfsacl_desc = {
97 .desc = {
98 .elem_size = 12,
99 .array_len = encode_entries ? entries : 0,
100 .xcode = xdr_nfsace_encode,
101 },
102 .acl = acl,
103 .typeflag = typeflag,
104 .uid = inode->i_uid,
105 .gid = inode->i_gid,
106 };
107 struct nfsacl_simple_acl aclbuf;
108 int err;
109
110 if (entries > NFS_ACL_MAX_ENTRIES ||
111 xdr_encode_word(buf, base, entries))
112 return -EINVAL;
113 if (encode_entries && acl && acl->a_count == 3) {
114 struct posix_acl *acl2 = &aclbuf.acl;
115
116 /* Avoid the use of posix_acl_alloc(). nfsacl_encode() is
117 * invoked in contexts where a memory allocation failure is
118 * fatal. Fortunately this fake ACL is small enough to
119 * construct on the stack. */
120 posix_acl_init(acl2, 4);
121
122 /* Insert entries in canonical order: other orders seem
123 to confuse Solaris VxFS. */
124 acl2->a_entries[0] = acl->a_entries[0]; /* ACL_USER_OBJ */
125 acl2->a_entries[1] = acl->a_entries[1]; /* ACL_GROUP_OBJ */
126 acl2->a_entries[2] = acl->a_entries[1]; /* ACL_MASK */
127 acl2->a_entries[2].e_tag = ACL_MASK;
128 acl2->a_entries[3] = acl->a_entries[2]; /* ACL_OTHER */
129 nfsacl_desc.acl = acl2;
130 }
131 err = xdr_encode_array2(buf, base + 4, &nfsacl_desc.desc);
132 if (!err)
133 err = 8 + nfsacl_desc.desc.elem_size *
134 nfsacl_desc.desc.array_len;
135 return err;
136 }
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
152 if (!nfsacl_desc->acl) {
153 if (desc->array_len > NFS_ACL_MAX_ENTRIES)
154 return -EINVAL;
155 nfsacl_desc->acl = posix_acl_alloc(desc->array_len, GFP_KERNEL);
156 if (!nfsacl_desc->acl)
157 return -ENOMEM;
158 nfsacl_desc->count = 0;
159 }
160
161 entry = &nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
162 entry->e_tag = ntohl(*p++) & ~NFS_ACL_DEFAULT;
163 entry->e_id = ntohl(*p++);
164 entry->e_perm = ntohl(*p++);
165
166 switch(entry->e_tag) {
167 case ACL_USER_OBJ:
168 case ACL_USER:
169 case ACL_GROUP_OBJ:
170 case ACL_GROUP:
171 case ACL_OTHER:
172 if (entry->e_perm & ~S_IRWXO)
173 return -EINVAL;
174 break;
175 case ACL_MASK:
176 /* Solaris sometimes sets additional bits in the mask */
177 entry->e_perm &= S_IRWXO;
178 break;
179 default:
180 return -EINVAL;
181 }
182
183 return 0;
184 }
185
186 static int
cmp_acl_entry(const void * x,const void * y)187 cmp_acl_entry(const void *x, const void *y)
188 {
189 const struct posix_acl_entry *a = x, *b = y;
190
191 if (a->e_tag != b->e_tag)
192 return a->e_tag - b->e_tag;
193 else if (a->e_id > b->e_id)
194 return 1;
195 else if (a->e_id < b->e_id)
196 return -1;
197 else
198 return 0;
199 }
200
201 /*
202 * Convert from a Solaris ACL to a POSIX 1003.1e draft 17 ACL.
203 */
204 static int
posix_acl_from_nfsacl(struct posix_acl * acl)205 posix_acl_from_nfsacl(struct posix_acl *acl)
206 {
207 struct posix_acl_entry *pa, *pe,
208 *group_obj = NULL, *mask = NULL;
209
210 if (!acl)
211 return 0;
212
213 sort(acl->a_entries, acl->a_count, sizeof(struct posix_acl_entry),
214 cmp_acl_entry, NULL);
215
216 /* Clear undefined identifier fields and find the ACL_GROUP_OBJ
217 and ACL_MASK entries. */
218 FOREACH_ACL_ENTRY(pa, acl, pe) {
219 switch(pa->e_tag) {
220 case ACL_USER_OBJ:
221 pa->e_id = ACL_UNDEFINED_ID;
222 break;
223 case ACL_GROUP_OBJ:
224 pa->e_id = ACL_UNDEFINED_ID;
225 group_obj = pa;
226 break;
227 case ACL_MASK:
228 mask = pa;
229 /* fall through */
230 case ACL_OTHER:
231 pa->e_id = ACL_UNDEFINED_ID;
232 break;
233 }
234 }
235 if (acl->a_count == 4 && group_obj && mask &&
236 mask->e_perm == group_obj->e_perm) {
237 /* remove bogus ACL_MASK entry */
238 memmove(mask, mask+1, (3 - (mask - acl->a_entries)) *
239 sizeof(struct posix_acl_entry));
240 acl->a_count = 3;
241 }
242 return 0;
243 }
244
245 /**
246 * nfsacl_decode - Decode an NFSv3 ACL
247 *
248 * @buf: xdr_buf containing XDR'd ACL data to decode
249 * @base: byte offset in xdr_buf where XDR'd ACL begins
250 * @aclcnt: count of ACEs in decoded posix_acl
251 * @pacl: buffer in which to place decoded posix_acl
252 *
253 * Returns the length of the decoded ACL in bytes, or a negative errno value.
254 */
nfsacl_decode(struct xdr_buf * buf,unsigned int base,unsigned int * aclcnt,struct posix_acl ** pacl)255 int nfsacl_decode(struct xdr_buf *buf, unsigned int base, unsigned int *aclcnt,
256 struct posix_acl **pacl)
257 {
258 struct nfsacl_decode_desc nfsacl_desc = {
259 .desc = {
260 .elem_size = 12,
261 .xcode = pacl ? xdr_nfsace_decode : NULL,
262 },
263 };
264 u32 entries;
265 int err;
266
267 if (xdr_decode_word(buf, base, &entries) ||
268 entries > NFS_ACL_MAX_ENTRIES)
269 return -EINVAL;
270 nfsacl_desc.desc.array_maxlen = entries;
271 err = xdr_decode_array2(buf, base + 4, &nfsacl_desc.desc);
272 if (err)
273 return err;
274 if (pacl) {
275 if (entries != nfsacl_desc.desc.array_len ||
276 posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
277 posix_acl_release(nfsacl_desc.acl);
278 return -EINVAL;
279 }
280 *pacl = nfsacl_desc.acl;
281 }
282 if (aclcnt)
283 *aclcnt = entries;
284 return 8 + nfsacl_desc.desc.elem_size *
285 nfsacl_desc.desc.array_len;
286 }
287