1 /*
2  * misc.c
3  *
4  * PURPOSE
5  *	Miscellaneous routines for the OSTA-UDF(tm) filesystem.
6  *
7  * COPYRIGHT
8  *	This file is distributed under the terms of the GNU General Public
9  *	License (GPL). Copies of the GPL can be obtained from:
10  *		ftp://prep.ai.mit.edu/pub/gnu/GPL
11  *	Each contributing author retains all rights to their own work.
12  *
13  *  (C) 1998 Dave Boynton
14  *  (C) 1998-2004 Ben Fennema
15  *  (C) 1999-2000 Stelias Computing Inc
16  *
17  * HISTORY
18  *
19  *  04/19/99 blf  partial support for reading/writing specific EA's
20  */
21 
22 #include "udfdecl.h"
23 
24 #include <linux/fs.h>
25 #include <linux/string.h>
26 #include <linux/crc-itu-t.h>
27 
28 #include "udf_i.h"
29 #include "udf_sb.h"
30 
udf_tgetblk(struct super_block * sb,udf_pblk_t block)31 struct buffer_head *udf_tgetblk(struct super_block *sb, udf_pblk_t block)
32 {
33 	if (UDF_QUERY_FLAG(sb, UDF_FLAG_VARCONV))
34 		return sb_getblk(sb, udf_fixed_to_variable(block));
35 	else
36 		return sb_getblk(sb, block);
37 }
38 
udf_tread(struct super_block * sb,udf_pblk_t block)39 struct buffer_head *udf_tread(struct super_block *sb, udf_pblk_t block)
40 {
41 	if (UDF_QUERY_FLAG(sb, UDF_FLAG_VARCONV))
42 		return sb_bread(sb, udf_fixed_to_variable(block));
43 	else
44 		return sb_bread(sb, block);
45 }
46 
udf_add_extendedattr(struct inode * inode,uint32_t size,uint32_t type,uint8_t loc)47 struct genericFormat *udf_add_extendedattr(struct inode *inode, uint32_t size,
48 					   uint32_t type, uint8_t loc)
49 {
50 	uint8_t *ea = NULL, *ad = NULL;
51 	int offset;
52 	uint16_t crclen;
53 	struct udf_inode_info *iinfo = UDF_I(inode);
54 
55 	ea = iinfo->i_data;
56 	if (iinfo->i_lenEAttr) {
57 		ad = iinfo->i_data + iinfo->i_lenEAttr;
58 	} else {
59 		ad = ea;
60 		size += sizeof(struct extendedAttrHeaderDesc);
61 	}
62 
63 	offset = inode->i_sb->s_blocksize - udf_file_entry_alloc_offset(inode) -
64 		iinfo->i_lenAlloc;
65 
66 	/* TODO - Check for FreeEASpace */
67 
68 	if (loc & 0x01 && offset >= size) {
69 		struct extendedAttrHeaderDesc *eahd;
70 		eahd = (struct extendedAttrHeaderDesc *)ea;
71 
72 		if (iinfo->i_lenAlloc)
73 			memmove(&ad[size], ad, iinfo->i_lenAlloc);
74 
75 		if (iinfo->i_lenEAttr) {
76 			/* check checksum/crc */
77 			if (eahd->descTag.tagIdent !=
78 					cpu_to_le16(TAG_IDENT_EAHD) ||
79 			    le32_to_cpu(eahd->descTag.tagLocation) !=
80 					iinfo->i_location.logicalBlockNum)
81 				return NULL;
82 		} else {
83 			struct udf_sb_info *sbi = UDF_SB(inode->i_sb);
84 
85 			size -= sizeof(struct extendedAttrHeaderDesc);
86 			iinfo->i_lenEAttr +=
87 				sizeof(struct extendedAttrHeaderDesc);
88 			eahd->descTag.tagIdent = cpu_to_le16(TAG_IDENT_EAHD);
89 			if (sbi->s_udfrev >= 0x0200)
90 				eahd->descTag.descVersion = cpu_to_le16(3);
91 			else
92 				eahd->descTag.descVersion = cpu_to_le16(2);
93 			eahd->descTag.tagSerialNum =
94 					cpu_to_le16(sbi->s_serial_number);
95 			eahd->descTag.tagLocation = cpu_to_le32(
96 					iinfo->i_location.logicalBlockNum);
97 			eahd->impAttrLocation = cpu_to_le32(0xFFFFFFFF);
98 			eahd->appAttrLocation = cpu_to_le32(0xFFFFFFFF);
99 		}
100 
101 		offset = iinfo->i_lenEAttr;
102 		if (type < 2048) {
103 			if (le32_to_cpu(eahd->appAttrLocation) <
104 					iinfo->i_lenEAttr) {
105 				uint32_t aal =
106 					le32_to_cpu(eahd->appAttrLocation);
107 				memmove(&ea[offset - aal + size],
108 					&ea[aal], offset - aal);
109 				offset -= aal;
110 				eahd->appAttrLocation =
111 						cpu_to_le32(aal + size);
112 			}
113 			if (le32_to_cpu(eahd->impAttrLocation) <
114 					iinfo->i_lenEAttr) {
115 				uint32_t ial =
116 					le32_to_cpu(eahd->impAttrLocation);
117 				memmove(&ea[offset - ial + size],
118 					&ea[ial], offset - ial);
119 				offset -= ial;
120 				eahd->impAttrLocation =
121 						cpu_to_le32(ial + size);
122 			}
123 		} else if (type < 65536) {
124 			if (le32_to_cpu(eahd->appAttrLocation) <
125 					iinfo->i_lenEAttr) {
126 				uint32_t aal =
127 					le32_to_cpu(eahd->appAttrLocation);
128 				memmove(&ea[offset - aal + size],
129 					&ea[aal], offset - aal);
130 				offset -= aal;
131 				eahd->appAttrLocation =
132 						cpu_to_le32(aal + size);
133 			}
134 		}
135 		/* rewrite CRC + checksum of eahd */
136 		crclen = sizeof(struct extendedAttrHeaderDesc) - sizeof(struct tag);
137 		eahd->descTag.descCRCLength = cpu_to_le16(crclen);
138 		eahd->descTag.descCRC = cpu_to_le16(crc_itu_t(0, (char *)eahd +
139 						sizeof(struct tag), crclen));
140 		eahd->descTag.tagChecksum = udf_tag_checksum(&eahd->descTag);
141 		iinfo->i_lenEAttr += size;
142 		return (struct genericFormat *)&ea[offset];
143 	}
144 
145 	return NULL;
146 }
147 
udf_get_extendedattr(struct inode * inode,uint32_t type,uint8_t subtype)148 struct genericFormat *udf_get_extendedattr(struct inode *inode, uint32_t type,
149 					   uint8_t subtype)
150 {
151 	struct genericFormat *gaf;
152 	uint8_t *ea = NULL;
153 	uint32_t offset;
154 	struct udf_inode_info *iinfo = UDF_I(inode);
155 
156 	ea = iinfo->i_data;
157 
158 	if (iinfo->i_lenEAttr) {
159 		struct extendedAttrHeaderDesc *eahd;
160 		eahd = (struct extendedAttrHeaderDesc *)ea;
161 
162 		/* check checksum/crc */
163 		if (eahd->descTag.tagIdent !=
164 				cpu_to_le16(TAG_IDENT_EAHD) ||
165 		    le32_to_cpu(eahd->descTag.tagLocation) !=
166 				iinfo->i_location.logicalBlockNum)
167 			return NULL;
168 
169 		if (type < 2048)
170 			offset = sizeof(struct extendedAttrHeaderDesc);
171 		else if (type < 65536)
172 			offset = le32_to_cpu(eahd->impAttrLocation);
173 		else
174 			offset = le32_to_cpu(eahd->appAttrLocation);
175 
176 		while (offset + sizeof(*gaf) < iinfo->i_lenEAttr) {
177 			uint32_t attrLength;
178 
179 			gaf = (struct genericFormat *)&ea[offset];
180 			attrLength = le32_to_cpu(gaf->attrLength);
181 
182 			/* Detect undersized elements and buffer overflows */
183 			if ((attrLength < sizeof(*gaf)) ||
184 			    (attrLength > (iinfo->i_lenEAttr - offset)))
185 				break;
186 
187 			if (le32_to_cpu(gaf->attrType) == type &&
188 					gaf->attrSubtype == subtype)
189 				return gaf;
190 			else
191 				offset += attrLength;
192 		}
193 	}
194 
195 	return NULL;
196 }
197 
198 /*
199  * udf_read_tagged
200  *
201  * PURPOSE
202  *	Read the first block of a tagged descriptor.
203  *
204  * HISTORY
205  *	July 1, 1997 - Andrew E. Mileski
206  *	Written, tested, and released.
207  */
udf_read_tagged(struct super_block * sb,uint32_t block,uint32_t location,uint16_t * ident)208 struct buffer_head *udf_read_tagged(struct super_block *sb, uint32_t block,
209 				    uint32_t location, uint16_t *ident)
210 {
211 	struct tag *tag_p;
212 	struct buffer_head *bh = NULL;
213 	u8 checksum;
214 
215 	/* Read the block */
216 	if (block == 0xFFFFFFFF)
217 		return NULL;
218 
219 	bh = udf_tread(sb, block);
220 	if (!bh) {
221 		udf_err(sb, "read failed, block=%u, location=%u\n",
222 			block, location);
223 		return NULL;
224 	}
225 
226 	tag_p = (struct tag *)(bh->b_data);
227 
228 	*ident = le16_to_cpu(tag_p->tagIdent);
229 
230 	if (location != le32_to_cpu(tag_p->tagLocation)) {
231 		udf_debug("location mismatch block %u, tag %u != %u\n",
232 			  block, le32_to_cpu(tag_p->tagLocation), location);
233 		goto error_out;
234 	}
235 
236 	/* Verify the tag checksum */
237 	checksum = udf_tag_checksum(tag_p);
238 	if (checksum != tag_p->tagChecksum) {
239 		udf_err(sb, "tag checksum failed, block %u: 0x%02x != 0x%02x\n",
240 			block, checksum, tag_p->tagChecksum);
241 		goto error_out;
242 	}
243 
244 	/* Verify the tag version */
245 	if (tag_p->descVersion != cpu_to_le16(0x0002U) &&
246 	    tag_p->descVersion != cpu_to_le16(0x0003U)) {
247 		udf_err(sb, "tag version 0x%04x != 0x0002 || 0x0003, block %u\n",
248 			le16_to_cpu(tag_p->descVersion), block);
249 		goto error_out;
250 	}
251 
252 	/* Verify the descriptor CRC */
253 	if (le16_to_cpu(tag_p->descCRCLength) + sizeof(struct tag) > sb->s_blocksize ||
254 	    le16_to_cpu(tag_p->descCRC) == crc_itu_t(0,
255 					bh->b_data + sizeof(struct tag),
256 					le16_to_cpu(tag_p->descCRCLength)))
257 		return bh;
258 
259 	udf_debug("Crc failure block %u: crc = %u, crclen = %u\n", block,
260 		  le16_to_cpu(tag_p->descCRC),
261 		  le16_to_cpu(tag_p->descCRCLength));
262 error_out:
263 	brelse(bh);
264 	return NULL;
265 }
266 
udf_read_ptagged(struct super_block * sb,struct kernel_lb_addr * loc,uint32_t offset,uint16_t * ident)267 struct buffer_head *udf_read_ptagged(struct super_block *sb,
268 				     struct kernel_lb_addr *loc,
269 				     uint32_t offset, uint16_t *ident)
270 {
271 	return udf_read_tagged(sb, udf_get_lb_pblock(sb, loc, offset),
272 			       loc->logicalBlockNum + offset, ident);
273 }
274 
udf_update_tag(char * data,int length)275 void udf_update_tag(char *data, int length)
276 {
277 	struct tag *tptr = (struct tag *)data;
278 	length -= sizeof(struct tag);
279 
280 	tptr->descCRCLength = cpu_to_le16(length);
281 	tptr->descCRC = cpu_to_le16(crc_itu_t(0, data + sizeof(struct tag), length));
282 	tptr->tagChecksum = udf_tag_checksum(tptr);
283 }
284 
udf_new_tag(char * data,uint16_t ident,uint16_t version,uint16_t snum,uint32_t loc,int length)285 void udf_new_tag(char *data, uint16_t ident, uint16_t version, uint16_t snum,
286 		 uint32_t loc, int length)
287 {
288 	struct tag *tptr = (struct tag *)data;
289 	tptr->tagIdent = cpu_to_le16(ident);
290 	tptr->descVersion = cpu_to_le16(version);
291 	tptr->tagSerialNum = cpu_to_le16(snum);
292 	tptr->tagLocation = cpu_to_le32(loc);
293 	udf_update_tag(data, length);
294 }
295 
udf_tag_checksum(const struct tag * t)296 u8 udf_tag_checksum(const struct tag *t)
297 {
298 	u8 *data = (u8 *)t;
299 	u8 checksum = 0;
300 	int i;
301 	for (i = 0; i < sizeof(struct tag); ++i)
302 		if (i != 4) /* position of checksum */
303 			checksum += data[i];
304 	return checksum;
305 }
306