1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/isofs/namei.c
4 *
5 * (C) 1992 Eric Youngdale Modified for ISO 9660 filesystem.
6 *
7 * (C) 1991 Linus Torvalds - minix filesystem
8 */
9
10 #include <linux/gfp.h>
11 #include "isofs.h"
12
isofs_dir_record_valid(struct iso_directory_record * de,unsigned long offset,unsigned long bufsize)13 bool isofs_dir_record_valid(struct iso_directory_record *de,
14 unsigned long offset,
15 unsigned long bufsize)
16 {
17 unsigned int len;
18 unsigned int name_len;
19 unsigned long min_len = offsetof(struct iso_directory_record, name);
20
21 if (offset > bufsize || bufsize - offset < min_len)
22 return false;
23
24 len = isonum_711(de->length);
25 name_len = isonum_711(de->name_len);
26 if (len < min_len || name_len > len - min_len)
27 return false;
28 if (len > bufsize - offset)
29 return false;
30 return true;
31 }
32
33 static int
isofs_cmp(struct dentry * dentry,const char * compare,int dlen)34 isofs_cmp(struct dentry *dentry, const char *compare, int dlen)
35 {
36 if (likely(!dentry->d_op))
37 return dentry->d_name.len != dlen || memcmp(dentry->d_name.name, compare, dlen);
38 return dentry->d_op->d_compare(NULL, dentry->d_name.len, dentry->d_name.name,
39 &QSTR_LEN(compare, dlen));
40 }
41
42 /*
43 * isofs_find_entry()
44 *
45 * finds an entry in the specified directory with the wanted name. It
46 * returns the inode number of the found entry, or 0 on error.
47 */
48 static unsigned long
isofs_find_entry(struct inode * dir,struct dentry * dentry,unsigned long * block_rv,unsigned long * offset_rv,char * tmpname)49 isofs_find_entry(struct inode *dir, struct dentry *dentry,
50 unsigned long *block_rv, unsigned long *offset_rv,
51 char *tmpname)
52 {
53 unsigned long bufsize = ISOFS_BUFFER_SIZE(dir);
54 unsigned char bufbits = ISOFS_BUFFER_BITS(dir);
55 unsigned long block, f_pos, offset, block_saved, offset_saved;
56 struct buffer_head *bh = NULL;
57 struct isofs_sb_info *sbi = ISOFS_SB(dir->i_sb);
58
59 if (!ISOFS_I(dir)->i_first_extent)
60 return 0;
61
62 f_pos = 0;
63 offset = 0;
64 block = 0;
65
66 while (f_pos < dir->i_size) {
67 struct iso_directory_record *de;
68 int de_len, match, i, dlen;
69 char *dpnt;
70
71 if (!bh) {
72 bh = isofs_bread(dir, block);
73 if (!bh)
74 return 0;
75 }
76
77 de = (struct iso_directory_record *) (bh->b_data + offset);
78
79 de_len = *(unsigned char *) de;
80 if (!de_len) {
81 brelse(bh);
82 bh = NULL;
83 f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1);
84 block = f_pos >> bufbits;
85 offset = 0;
86 continue;
87 }
88
89 block_saved = bh->b_blocknr;
90 offset_saved = offset;
91 offset += de_len;
92 f_pos += de_len;
93
94 if (!isofs_dir_record_valid(de, offset_saved, bufsize)) {
95 printk(KERN_NOTICE "iso9660: Corrupted directory entry"
96 " in block %lu of inode %llu\n", block,
97 dir->i_ino);
98 brelse(bh);
99 return 0;
100 }
101 dlen = de->name_len[0];
102 dpnt = de->name;
103
104 if (sbi->s_rock &&
105 ((i = get_rock_ridge_filename(de, tmpname, dir)))) {
106 dlen = i; /* possibly -1 */
107 dpnt = tmpname;
108 #ifdef CONFIG_JOLIET
109 } else if (sbi->s_joliet_level) {
110 dlen = get_joliet_filename(de, tmpname, dir);
111 dpnt = tmpname;
112 #endif
113 } else if (sbi->s_mapping == 'a') {
114 dlen = get_acorn_filename(de, tmpname, dir);
115 dpnt = tmpname;
116 } else if (sbi->s_mapping == 'n') {
117 dlen = isofs_name_translate(de, tmpname, dir);
118 dpnt = tmpname;
119 }
120
121 /*
122 * Skip hidden or associated files unless hide or showassoc,
123 * respectively, is set
124 */
125 match = 0;
126 if (dlen > 0 &&
127 (!sbi->s_hide ||
128 (!(de->flags[-sbi->s_high_sierra] & 1))) &&
129 (sbi->s_showassoc ||
130 (!(de->flags[-sbi->s_high_sierra] & 4)))) {
131 if (dpnt && (dlen > 1 || dpnt[0] > 1))
132 match = (isofs_cmp(dentry, dpnt, dlen) == 0);
133 }
134 if (match) {
135 isofs_normalize_block_and_offset(de,
136 &block_saved,
137 &offset_saved);
138 *block_rv = block_saved;
139 *offset_rv = offset_saved;
140 brelse(bh);
141 return 1;
142 }
143 }
144 brelse(bh);
145 return 0;
146 }
147
isofs_lookup(struct inode * dir,struct dentry * dentry,unsigned int flags)148 struct dentry *isofs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
149 {
150 int found;
151 unsigned long block;
152 unsigned long offset;
153 struct inode *inode;
154 char *tmpname;
155
156 tmpname = kmalloc(1024, GFP_USER);
157 if (!tmpname)
158 return ERR_PTR(-ENOMEM);
159
160 found = isofs_find_entry(dir, dentry, &block, &offset, tmpname);
161 kfree(tmpname);
162
163 inode = found ? isofs_iget(dir->i_sb, block, offset) : NULL;
164
165 return d_splice_alias(inode, dentry);
166 }
167