1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *  linux/fs/adfs/dir_fplus.c
4 *
5 *  Copyright (C) 1997-1999 Russell King
6 */
7#include "adfs.h"
8#include "dir_fplus.h"
9
10/* Return the byte offset to directory entry pos */
11static unsigned int adfs_fplus_offset(const struct adfs_bigdirheader *h,
12				      unsigned int pos)
13{
14	return offsetof(struct adfs_bigdirheader, bigdirname) +
15	       ALIGN(le32_to_cpu(h->bigdirnamelen), 4) +
16	       pos * sizeof(struct adfs_bigdirentry);
17}
18
19static int adfs_fplus_validate_header(const struct adfs_bigdirheader *h)
20{
21	unsigned int size = le32_to_cpu(h->bigdirsize);
22	unsigned int len;
23
24	if (h->bigdirversion[0] != 0 || h->bigdirversion[1] != 0 ||
25	    h->bigdirversion[2] != 0 ||
26	    h->bigdirstartname != cpu_to_le32(BIGDIRSTARTNAME) ||
27	    !size || size & 2047 || size > SZ_4M)
28		return -EIO;
29
30	size -= sizeof(struct adfs_bigdirtail) +
31		offsetof(struct adfs_bigdirheader, bigdirname);
32
33	/* Check that bigdirnamelen fits within the directory */
34	len = ALIGN(le32_to_cpu(h->bigdirnamelen), 4);
35	if (len > size)
36		return -EIO;
37
38	size -= len;
39
40	/* Check that bigdirnamesize fits within the directory */
41	len = le32_to_cpu(h->bigdirnamesize);
42	if (len > size)
43		return -EIO;
44
45	size -= len;
46
47	/*
48	 * Avoid division, we know that absolute maximum number of entries
49	 * can not be so large to cause overflow of the multiplication below.
50	 */
51	len = le32_to_cpu(h->bigdirentries);
52	if (len > SZ_4M / sizeof(struct adfs_bigdirentry) ||
53	    len * sizeof(struct adfs_bigdirentry) > size)
54		return -EIO;
55
56	return 0;
57}
58
59static int adfs_fplus_validate_tail(const struct adfs_bigdirheader *h,
60				    const struct adfs_bigdirtail *t)
61{
62	if (t->bigdirendname != cpu_to_le32(BIGDIRENDNAME) ||
63	    t->bigdirendmasseq != h->startmasseq ||
64	    t->reserved[0] != 0 || t->reserved[1] != 0)
65		return -EIO;
66
67	return 0;
68}
69
70static u8 adfs_fplus_checkbyte(struct adfs_dir *dir)
71{
72	struct adfs_bigdirheader *h = dir->bighead;
73	struct adfs_bigdirtail *t = dir->bigtail;
74	unsigned int end, bs, bi, i;
75	__le32 *bp;
76	u32 dircheck;
77
78	end = adfs_fplus_offset(h, le32_to_cpu(h->bigdirentries)) +
79		le32_to_cpu(h->bigdirnamesize);
80
81	/* Accumulate the contents of the header, entries and names */
82	for (dircheck = 0, bi = 0; end; bi++) {
83		bp = (void *)dir->bhs[bi]->b_data;
84		bs = dir->bhs[bi]->b_size;
85		if (bs > end)
86			bs = end;
87
88		for (i = 0; i < bs; i += sizeof(u32))
89			dircheck = ror32(dircheck, 13) ^ le32_to_cpup(bp++);
90
91		end -= bs;
92	}
93
94	/* Accumulate the contents of the tail except for the check byte */
95	dircheck = ror32(dircheck, 13) ^ le32_to_cpu(t->bigdirendname);
96	dircheck = ror32(dircheck, 13) ^ t->bigdirendmasseq;
97	dircheck = ror32(dircheck, 13) ^ t->reserved[0];
98	dircheck = ror32(dircheck, 13) ^ t->reserved[1];
99
100	return dircheck ^ dircheck >> 8 ^ dircheck >> 16 ^ dircheck >> 24;
101}
102
103static int adfs_fplus_read(struct super_block *sb, u32 indaddr,
104			   unsigned int size, struct adfs_dir *dir)
105{
106	struct adfs_bigdirheader *h;
107	struct adfs_bigdirtail *t;
108	unsigned int dirsize;
109	int ret;
110
111	/* Read first buffer */
112	ret = adfs_dir_read_buffers(sb, indaddr, sb->s_blocksize, dir);
113	if (ret)
114		return ret;
115
116	dir->bighead = h = (void *)dir->bhs[0]->b_data;
117	ret = adfs_fplus_validate_header(h);
118	if (ret) {
119		adfs_error(sb, "dir %06x has malformed header", indaddr);
120		goto out;
121	}
122
123	dirsize = le32_to_cpu(h->bigdirsize);
124	if (size && dirsize != size) {
125		adfs_msg(sb, KERN_WARNING,
126			 "dir %06x header size %X does not match directory size %X",
127			 indaddr, dirsize, size);
128	}
129
130	/* Read remaining buffers */
131	ret = adfs_dir_read_buffers(sb, indaddr, dirsize, dir);
132	if (ret)
133		return ret;
134
135	dir->bigtail = t = (struct adfs_bigdirtail *)
136		(dir->bhs[dir->nr_buffers - 1]->b_data + (sb->s_blocksize - 8));
137
138	ret = adfs_fplus_validate_tail(h, t);
139	if (ret) {
140		adfs_error(sb, "dir %06x has malformed tail", indaddr);
141		goto out;
142	}
143
144	if (adfs_fplus_checkbyte(dir) != t->bigdircheckbyte) {
145		adfs_error(sb, "dir %06x checkbyte mismatch\n", indaddr);
146		goto out;
147	}
148
149	dir->parent_id = le32_to_cpu(h->bigdirparent);
150	return 0;
151
152out:
153	adfs_dir_relse(dir);
154
155	return ret;
156}
157
158static int
159adfs_fplus_setpos(struct adfs_dir *dir, unsigned int fpos)
160{
161	int ret = -ENOENT;
162
163	if (fpos <= le32_to_cpu(dir->bighead->bigdirentries)) {
164		dir->pos = fpos;
165		ret = 0;
166	}
167
168	return ret;
169}
170
171static int
172adfs_fplus_getnext(struct adfs_dir *dir, struct object_info *obj)
173{
174	struct adfs_bigdirheader *h = dir->bighead;
175	struct adfs_bigdirentry bde;
176	unsigned int offset;
177	int ret;
178
179	if (dir->pos >= le32_to_cpu(h->bigdirentries))
180		return -ENOENT;
181
182	offset = adfs_fplus_offset(h, dir->pos);
183
184	ret = adfs_dir_copyfrom(&bde, dir, offset,
185				sizeof(struct adfs_bigdirentry));
186	if (ret)
187		return ret;
188
189	obj->loadaddr = le32_to_cpu(bde.bigdirload);
190	obj->execaddr = le32_to_cpu(bde.bigdirexec);
191	obj->size     = le32_to_cpu(bde.bigdirlen);
192	obj->indaddr  = le32_to_cpu(bde.bigdirindaddr);
193	obj->attr     = le32_to_cpu(bde.bigdirattr);
194	obj->name_len = le32_to_cpu(bde.bigdirobnamelen);
195
196	offset = adfs_fplus_offset(h, le32_to_cpu(h->bigdirentries));
197	offset += le32_to_cpu(bde.bigdirobnameptr);
198
199	ret = adfs_dir_copyfrom(obj->name, dir, offset, obj->name_len);
200	if (ret)
201		return ret;
202
203	adfs_object_fixup(dir, obj);
204
205	dir->pos += 1;
206
207	return 0;
208}
209
210static int adfs_fplus_iterate(struct adfs_dir *dir, struct dir_context *ctx)
211{
212	struct object_info obj;
213
214	if ((ctx->pos - 2) >> 32)
215		return 0;
216
217	if (adfs_fplus_setpos(dir, ctx->pos - 2))
218		return 0;
219
220	while (!adfs_fplus_getnext(dir, &obj)) {
221		if (!dir_emit(ctx, obj.name, obj.name_len,
222			      obj.indaddr, DT_UNKNOWN))
223			break;
224		ctx->pos++;
225	}
226
227	return 0;
228}
229
230static int adfs_fplus_update(struct adfs_dir *dir, struct object_info *obj)
231{
232	struct adfs_bigdirheader *h = dir->bighead;
233	struct adfs_bigdirentry bde;
234	int offset, end, ret;
235
236	offset = adfs_fplus_offset(h, 0) - sizeof(bde);
237	end = adfs_fplus_offset(h, le32_to_cpu(h->bigdirentries));
238
239	do {
240		offset += sizeof(bde);
241		if (offset >= end) {
242			adfs_error(dir->sb, "unable to locate entry to update");
243			return -ENOENT;
244		}
245		ret = adfs_dir_copyfrom(&bde, dir, offset, sizeof(bde));
246		if (ret) {
247			adfs_error(dir->sb, "error reading directory entry");
248			return -ENOENT;
249		}
250	} while (le32_to_cpu(bde.bigdirindaddr) != obj->indaddr);
251
252	bde.bigdirload    = cpu_to_le32(obj->loadaddr);
253	bde.bigdirexec    = cpu_to_le32(obj->execaddr);
254	bde.bigdirlen     = cpu_to_le32(obj->size);
255	bde.bigdirindaddr = cpu_to_le32(obj->indaddr);
256	bde.bigdirattr    = cpu_to_le32(obj->attr);
257
258	return adfs_dir_copyto(dir, offset, &bde, sizeof(bde));
259}
260
261static int adfs_fplus_commit(struct adfs_dir *dir)
262{
263	int ret;
264
265	/* Increment directory sequence number */
266	dir->bighead->startmasseq += 1;
267	dir->bigtail->bigdirendmasseq += 1;
268
269	/* Update directory check byte */
270	dir->bigtail->bigdircheckbyte = adfs_fplus_checkbyte(dir);
271
272	/* Make sure the directory still validates correctly */
273	ret = adfs_fplus_validate_header(dir->bighead);
274	if (ret == 0)
275		ret = adfs_fplus_validate_tail(dir->bighead, dir->bigtail);
276
277	return ret;
278}
279
280const struct adfs_dir_ops adfs_fplus_dir_ops = {
281	.read		= adfs_fplus_read,
282	.iterate	= adfs_fplus_iterate,
283	.setpos		= adfs_fplus_setpos,
284	.getnext	= adfs_fplus_getnext,
285	.update		= adfs_fplus_update,
286	.commit		= adfs_fplus_commit,
287};
288