/home/lenb/src/to-linus-stable branch 'acpi-2.6.12'
[linux-2.6] / fs / nfs_common / nfsacl.c
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/sunrpc/xdr.h>
26 #include <linux/nfsacl.h>
27 #include <linux/nfs3.h>
28 #include <linux/sort.h>
29
30 MODULE_LICENSE("GPL");
31
32 EXPORT_SYMBOL(nfsacl_encode);
33 EXPORT_SYMBOL(nfsacl_decode);
34
35 struct nfsacl_encode_desc {
36         struct xdr_array2_desc desc;
37         unsigned int count;
38         struct posix_acl *acl;
39         int typeflag;
40         uid_t uid;
41         gid_t gid;
42 };
43
44 static int
45 xdr_nfsace_encode(struct xdr_array2_desc *desc, void *elem)
46 {
47         struct nfsacl_encode_desc *nfsacl_desc =
48                 (struct nfsacl_encode_desc *) desc;
49         u32 *p = (u32 *) elem;
50
51         if (nfsacl_desc->count < nfsacl_desc->acl->a_count) {
52                 struct posix_acl_entry *entry =
53                         &nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
54
55                 *p++ = htonl(entry->e_tag | nfsacl_desc->typeflag);
56                 switch(entry->e_tag) {
57                         case ACL_USER_OBJ:
58                                 *p++ = htonl(nfsacl_desc->uid);
59                                 break;
60                         case ACL_GROUP_OBJ:
61                                 *p++ = htonl(nfsacl_desc->gid);
62                                 break;
63                         case ACL_USER:
64                         case ACL_GROUP:
65                                 *p++ = htonl(entry->e_id);
66                                 break;
67                         default:  /* Solaris depends on that! */
68                                 *p++ = 0;
69                                 break;
70                 }
71                 *p++ = htonl(entry->e_perm & S_IRWXO);
72         } else {
73                 const struct posix_acl_entry *pa, *pe;
74                 int group_obj_perm = ACL_READ|ACL_WRITE|ACL_EXECUTE;
75
76                 FOREACH_ACL_ENTRY(pa, nfsacl_desc->acl, pe) {
77                         if (pa->e_tag == ACL_GROUP_OBJ) {
78                                 group_obj_perm = pa->e_perm & S_IRWXO;
79                                 break;
80                         }
81                 }
82                 /* fake up ACL_MASK entry */
83                 *p++ = htonl(ACL_MASK | nfsacl_desc->typeflag);
84                 *p++ = htonl(0);
85                 *p++ = htonl(group_obj_perm);
86         }
87
88         return 0;
89 }
90
91 unsigned int
92 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         int err;
108
109         if (entries > NFS_ACL_MAX_ENTRIES ||
110             xdr_encode_word(buf, base, entries))
111                 return -EINVAL;
112         err = xdr_encode_array2(buf, base + 4, &nfsacl_desc.desc);
113         if (!err)
114                 err = 8 + nfsacl_desc.desc.elem_size *
115                           nfsacl_desc.desc.array_len;
116         return err;
117 }
118
119 struct nfsacl_decode_desc {
120         struct xdr_array2_desc desc;
121         unsigned int count;
122         struct posix_acl *acl;
123 };
124
125 static int
126 xdr_nfsace_decode(struct xdr_array2_desc *desc, void *elem)
127 {
128         struct nfsacl_decode_desc *nfsacl_desc =
129                 (struct nfsacl_decode_desc *) desc;
130         u32 *p = (u32 *) elem;
131         struct posix_acl_entry *entry;
132
133         if (!nfsacl_desc->acl) {
134                 if (desc->array_len > NFS_ACL_MAX_ENTRIES)
135                         return -EINVAL;
136                 nfsacl_desc->acl = posix_acl_alloc(desc->array_len, GFP_KERNEL);
137                 if (!nfsacl_desc->acl)
138                         return -ENOMEM;
139                 nfsacl_desc->count = 0;
140         }
141
142         entry = &nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
143         entry->e_tag = ntohl(*p++) & ~NFS_ACL_DEFAULT;
144         entry->e_id = ntohl(*p++);
145         entry->e_perm = ntohl(*p++);
146
147         switch(entry->e_tag) {
148                 case ACL_USER_OBJ:
149                 case ACL_USER:
150                 case ACL_GROUP_OBJ:
151                 case ACL_GROUP:
152                 case ACL_OTHER:
153                         if (entry->e_perm & ~S_IRWXO)
154                                 return -EINVAL;
155                         break;
156                 case ACL_MASK:
157                         /* Solaris sometimes sets additonal bits in the mask */
158                         entry->e_perm &= S_IRWXO;
159                         break;
160                 default:
161                         return -EINVAL;
162         }
163
164         return 0;
165 }
166
167 static int
168 cmp_acl_entry(const void *x, const void *y)
169 {
170         const struct posix_acl_entry *a = x, *b = y;
171
172         if (a->e_tag != b->e_tag)
173                 return a->e_tag - b->e_tag;
174         else if (a->e_id > b->e_id)
175                 return 1;
176         else if (a->e_id < b->e_id)
177                 return -1;
178         else
179                 return 0;
180 }
181
182 /*
183  * Convert from a Solaris ACL to a POSIX 1003.1e draft 17 ACL.
184  */
185 static int
186 posix_acl_from_nfsacl(struct posix_acl *acl)
187 {
188         struct posix_acl_entry *pa, *pe,
189                *group_obj = NULL, *mask = NULL;
190
191         if (!acl)
192                 return 0;
193
194         sort(acl->a_entries, acl->a_count, sizeof(struct posix_acl_entry),
195              cmp_acl_entry, NULL);
196
197         /* Clear undefined identifier fields and find the ACL_GROUP_OBJ
198            and ACL_MASK entries. */
199         FOREACH_ACL_ENTRY(pa, acl, pe) {
200                 switch(pa->e_tag) {
201                         case ACL_USER_OBJ:
202                                 pa->e_id = ACL_UNDEFINED_ID;
203                                 break;
204                         case ACL_GROUP_OBJ:
205                                 pa->e_id = ACL_UNDEFINED_ID;
206                                 group_obj = pa;
207                                 break;
208                         case ACL_MASK:
209                                 mask = pa;
210                                 /* fall through */
211                         case ACL_OTHER:
212                                 pa->e_id = ACL_UNDEFINED_ID;
213                                 break;
214                 }
215         }
216         if (acl->a_count == 4 && group_obj && mask &&
217             mask->e_perm == group_obj->e_perm) {
218                 /* remove bogus ACL_MASK entry */
219                 memmove(mask, mask+1, (3 - (mask - acl->a_entries)) *
220                                       sizeof(struct posix_acl_entry));
221                 acl->a_count = 3;
222         }
223         return 0;
224 }
225
226 unsigned int
227 nfsacl_decode(struct xdr_buf *buf, unsigned int base, unsigned int *aclcnt,
228               struct posix_acl **pacl)
229 {
230         struct nfsacl_decode_desc nfsacl_desc = {
231                 .desc = {
232                         .elem_size = 12,
233                         .xcode = pacl ? xdr_nfsace_decode : NULL,
234                 },
235         };
236         u32 entries;
237         int err;
238
239         if (xdr_decode_word(buf, base, &entries) ||
240             entries > NFS_ACL_MAX_ENTRIES)
241                 return -EINVAL;
242         err = xdr_decode_array2(buf, base + 4, &nfsacl_desc.desc);
243         if (err)
244                 return err;
245         if (pacl) {
246                 if (entries != nfsacl_desc.desc.array_len ||
247                     posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
248                         posix_acl_release(nfsacl_desc.acl);
249                         return -EINVAL;
250                 }
251                 *pacl = nfsacl_desc.acl;
252         }
253         if (aclcnt)
254                 *aclcnt = entries;
255         return 8 + nfsacl_desc.desc.elem_size *
256                    nfsacl_desc.desc.array_len;
257 }