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
30MODULE_LICENSE("GPL");
31
32EXPORT_SYMBOL(nfsacl_encode);
33EXPORT_SYMBOL(nfsacl_decode);
34
35struct 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
44static int
45xdr_nfsace_encode(struct xdr_array2_desc *desc, void *elem)
46{
47	struct nfsacl_encode_desc *nfsacl_desc =
48		(struct nfsacl_encode_desc *) desc;
49	__be32 *p = elem;
50
51	struct posix_acl_entry *entry =
52		&nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
53
54	*p++ = htonl(entry->e_tag | nfsacl_desc->typeflag);
55	switch(entry->e_tag) {
56		case ACL_USER_OBJ:
57			*p++ = htonl(nfsacl_desc->uid);
58			break;
59		case ACL_GROUP_OBJ:
60			*p++ = htonl(nfsacl_desc->gid);
61			break;
62		case ACL_USER:
63		case ACL_GROUP:
64			*p++ = htonl(entry->e_id);
65			break;
66		default:  /* Solaris depends on that! */
67			*p++ = 0;
68			break;
69	}
70	*p++ = htonl(entry->e_perm & S_IRWXO);
71	return 0;
72}
73
74unsigned int
75nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
76	      struct posix_acl *acl, int encode_entries, int typeflag)
77{
78	int entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
79	struct nfsacl_encode_desc nfsacl_desc = {
80		.desc = {
81			.elem_size = 12,
82			.array_len = encode_entries ? entries : 0,
83			.xcode = xdr_nfsace_encode,
84		},
85		.acl = acl,
86		.typeflag = typeflag,
87		.uid = inode->i_uid,
88		.gid = inode->i_gid,
89	};
90	int err;
91	struct posix_acl *acl2 = NULL;
92
93	if (entries > NFS_ACL_MAX_ENTRIES ||
94	    xdr_encode_word(buf, base, entries))
95		return -EINVAL;
96	if (encode_entries && acl && acl->a_count == 3) {
97		/* Fake up an ACL_MASK entry. */
98		acl2 = posix_acl_alloc(4, GFP_KERNEL);
99		if (!acl2)
100			return -ENOMEM;
101		/* Insert entries in canonical order: other orders seem
102		 to confuse Solaris VxFS. */
103		acl2->a_entries[0] = acl->a_entries[0];  /* ACL_USER_OBJ */
104		acl2->a_entries[1] = acl->a_entries[1];  /* ACL_GROUP_OBJ */
105		acl2->a_entries[2] = acl->a_entries[1];  /* ACL_MASK */
106		acl2->a_entries[2].e_tag = ACL_MASK;
107		acl2->a_entries[3] = acl->a_entries[2];  /* ACL_OTHER */
108		nfsacl_desc.acl = acl2;
109	}
110	err = xdr_encode_array2(buf, base + 4, &nfsacl_desc.desc);
111	if (acl2)
112		posix_acl_release(acl2);
113	if (!err)
114		err = 8 + nfsacl_desc.desc.elem_size *
115			  nfsacl_desc.desc.array_len;
116	return err;
117}
118
119struct nfsacl_decode_desc {
120	struct xdr_array2_desc desc;
121	unsigned int count;
122	struct posix_acl *acl;
123};
124
125static int
126xdr_nfsace_decode(struct xdr_array2_desc *desc, void *elem)
127{
128	struct nfsacl_decode_desc *nfsacl_desc =
129		(struct nfsacl_decode_desc *) desc;
130	__be32 *p = 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
167static int
168cmp_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 */
185static int
186posix_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
226unsigned int
227nfsacl_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	nfsacl_desc.desc.array_maxlen = entries;
243	err = xdr_decode_array2(buf, base + 4, &nfsacl_desc.desc);
244	if (err)
245		return err;
246	if (pacl) {
247		if (entries != nfsacl_desc.desc.array_len ||
248		    posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
249			posix_acl_release(nfsacl_desc.acl);
250			return -EINVAL;
251		}
252		*pacl = nfsacl_desc.acl;
253	}
254	if (aclcnt)
255		*aclcnt = entries;
256	return 8 + nfsacl_desc.desc.elem_size *
257		   nfsacl_desc.desc.array_len;
258}
259