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 */
11 static 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
19 static 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
59 static 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
70 static 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
103 static 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
152 out:
153 adfs_dir_relse(dir);
154
155 return ret;
156 }
157
158 static int
159 adfs_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
171 static int
172 adfs_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
210 static 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
230 static 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
261 static 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
280 const 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
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