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a257cdd0 AG |
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> | |
5a0e3ad6 | 25 | #include <linux/gfp.h> |
a257cdd0 AG |
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 | ||
d716f0b8 TM |
33 | EXPORT_SYMBOL_GPL(nfsacl_encode); |
34 | EXPORT_SYMBOL_GPL(nfsacl_decode); | |
a257cdd0 AG |
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 | ||
f61f6da0 CL |
45 | struct nfsacl_simple_acl { |
46 | struct posix_acl acl; | |
47 | struct posix_acl_entry ace[4]; | |
48 | }; | |
49 | ||
a257cdd0 AG |
50 | static int |
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; | |
83bbe2ef | 55 | __be32 *p = elem; |
a257cdd0 | 56 | |
22c1ea44 AG |
57 | struct posix_acl_entry *entry = |
58 | &nfsacl_desc->acl->a_entries[nfsacl_desc->count++]; | |
a257cdd0 | 59 | |
22c1ea44 AG |
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; | |
a257cdd0 | 75 | } |
22c1ea44 | 76 | *p++ = htonl(entry->e_perm & S_IRWXO); |
a257cdd0 AG |
77 | return 0; |
78 | } | |
79 | ||
731f3f48 CL |
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 | */ | |
92 | int nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode, | |
93 | struct posix_acl *acl, int encode_entries, int typeflag) | |
a257cdd0 AG |
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 | }; | |
f61f6da0 | 107 | struct nfsacl_simple_acl aclbuf; |
a257cdd0 AG |
108 | int err; |
109 | ||
110 | if (entries > NFS_ACL_MAX_ENTRIES || | |
111 | xdr_encode_word(buf, base, entries)) | |
112 | return -EINVAL; | |
22c1ea44 | 113 | if (encode_entries && acl && acl->a_count == 3) { |
f61f6da0 CL |
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. */ | |
f61f6da0 CL |
120 | posix_acl_init(acl2, 4); |
121 | ||
22c1ea44 AG |
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 | } | |
a257cdd0 AG |
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 | |
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; | |
83bbe2ef | 149 | __be32 *p = elem; |
a257cdd0 AG |
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 additonal 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 | |
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 | |
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 | ||
731f3f48 CL |
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 | */ | |
255 | int nfsacl_decode(struct xdr_buf *buf, unsigned int base, unsigned int *aclcnt, | |
256 | struct posix_acl **pacl) | |
a257cdd0 AG |
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; | |
58fcb8df | 270 | nfsacl_desc.desc.array_maxlen = entries; |
a257cdd0 AG |
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 | } |