• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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 */
adfs_fplus_offset(const struct adfs_bigdirheader * h,unsigned int 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  
adfs_fplus_validate_header(const struct adfs_bigdirheader * h)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  
adfs_fplus_validate_tail(const struct adfs_bigdirheader * h,const struct adfs_bigdirtail * t)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  
adfs_fplus_checkbyte(struct adfs_dir * dir)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  
adfs_fplus_read(struct super_block * sb,u32 indaddr,unsigned int size,struct adfs_dir * dir)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
adfs_fplus_setpos(struct adfs_dir * dir,unsigned int fpos)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
adfs_fplus_getnext(struct adfs_dir * dir,struct object_info * obj)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  
adfs_fplus_iterate(struct adfs_dir * dir,struct dir_context * ctx)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  
adfs_fplus_update(struct adfs_dir * dir,struct object_info * obj)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  
adfs_fplus_commit(struct adfs_dir * dir)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