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880a13c4 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
e6459606 PA |
2 | /* ----------------------------------------------------------------------- * |
3 | * | |
4 | * Copyright 2012 Intel Corporation; author H. Peter Anvin | |
5 | * | |
e6459606 PA |
6 | * ----------------------------------------------------------------------- */ |
7 | ||
8 | /* | |
9 | * earlycpio.c | |
10 | * | |
11 | * Find a specific cpio member; must precede any compressed content. | |
12 | * This is used to locate data items in the initramfs used by the | |
13 | * kernel itself during early boot (before the main initramfs is | |
14 | * decompressed.) It is the responsibility of the initramfs creator | |
15 | * to ensure that these items are uncompressed at the head of the | |
16 | * blob. Depending on the boot loader or package tool that may be a | |
17 | * separate file or part of the same file. | |
18 | */ | |
19 | ||
20 | #include <linux/earlycpio.h> | |
21 | #include <linux/kernel.h> | |
22 | #include <linux/string.h> | |
23 | ||
24 | enum cpio_fields { | |
25 | C_MAGIC, | |
26 | C_INO, | |
27 | C_MODE, | |
28 | C_UID, | |
29 | C_GID, | |
30 | C_NLINK, | |
31 | C_MTIME, | |
32 | C_FILESIZE, | |
33 | C_MAJ, | |
34 | C_MIN, | |
35 | C_RMAJ, | |
36 | C_RMIN, | |
37 | C_NAMESIZE, | |
38 | C_CHKSUM, | |
39 | C_NFIELDS | |
40 | }; | |
41 | ||
42 | /** | |
c95c2d32 | 43 | * find_cpio_data - Search for files in an uncompressed cpio |
598bae70 | 44 | * @path: The directory to search for, including a slash at the end |
4e20ace0 | 45 | * @data: Pointer to the cpio archive or a header inside |
598bae70 TC |
46 | * @len: Remaining length of the cpio based on data pointer |
47 | * @nextoff: When a matching file is found, this is the offset from the | |
48 | * beginning of the cpio to the beginning of the next file, not the | |
49 | * matching file itself. It can be used to iterate through the cpio | |
50 | * to find all files inside of a directory path. | |
e6459606 | 51 | * |
c95c2d32 | 52 | * Return: &struct cpio_data containing the address, length and |
598bae70 TC |
53 | * filename (with the directory path cut off) of the found file. |
54 | * If you search for a filename and not for files in a directory, | |
55 | * pass the absolute path of the filename in the cpio and make sure | |
56 | * the match returned an empty filename string. | |
e6459606 PA |
57 | */ |
58 | ||
0db0628d | 59 | struct cpio_data find_cpio_data(const char *path, void *data, |
598bae70 | 60 | size_t len, long *nextoff) |
e6459606 PA |
61 | { |
62 | const size_t cpio_header_len = 8*C_NFIELDS - 2; | |
63 | struct cpio_data cd = { NULL, 0, "" }; | |
64 | const char *p, *dptr, *nptr; | |
65 | unsigned int ch[C_NFIELDS], *chp, v; | |
66 | unsigned char c, x; | |
67 | size_t mypathsize = strlen(path); | |
68 | int i, j; | |
69 | ||
70 | p = data; | |
71 | ||
72 | while (len > cpio_header_len) { | |
73 | if (!*p) { | |
74 | /* All cpio headers need to be 4-byte aligned */ | |
75 | p += 4; | |
76 | len -= 4; | |
77 | continue; | |
78 | } | |
79 | ||
80 | j = 6; /* The magic field is only 6 characters */ | |
81 | chp = ch; | |
82 | for (i = C_NFIELDS; i; i--) { | |
83 | v = 0; | |
84 | while (j--) { | |
85 | v <<= 4; | |
86 | c = *p++; | |
87 | ||
88 | x = c - '0'; | |
89 | if (x < 10) { | |
90 | v += x; | |
91 | continue; | |
92 | } | |
93 | ||
94 | x = (c | 0x20) - 'a'; | |
95 | if (x < 6) { | |
96 | v += x + 10; | |
97 | continue; | |
98 | } | |
99 | ||
100 | goto quit; /* Invalid hexadecimal */ | |
101 | } | |
102 | *chp++ = v; | |
103 | j = 8; /* All other fields are 8 characters */ | |
104 | } | |
105 | ||
106 | if ((ch[C_MAGIC] - 0x070701) > 1) | |
107 | goto quit; /* Invalid magic */ | |
108 | ||
109 | len -= cpio_header_len; | |
110 | ||
111 | dptr = PTR_ALIGN(p + ch[C_NAMESIZE], 4); | |
112 | nptr = PTR_ALIGN(dptr + ch[C_FILESIZE], 4); | |
113 | ||
114 | if (nptr > p + len || dptr < p || nptr < dptr) | |
115 | goto quit; /* Buffer overrun */ | |
116 | ||
117 | if ((ch[C_MODE] & 0170000) == 0100000 && | |
118 | ch[C_NAMESIZE] >= mypathsize && | |
119 | !memcmp(p, path, mypathsize)) { | |
7557933e BP |
120 | |
121 | if (nextoff) | |
122 | *nextoff = (long)nptr - (long)data; | |
123 | ||
e6459606 PA |
124 | if (ch[C_NAMESIZE] - mypathsize >= MAX_CPIO_FILE_NAME) { |
125 | pr_warn( | |
126 | "File %s exceeding MAX_CPIO_FILE_NAME [%d]\n", | |
127 | p, MAX_CPIO_FILE_NAME); | |
128 | } | |
977bbf43 | 129 | strscpy(cd.name, p + mypathsize, MAX_CPIO_FILE_NAME); |
e6459606 PA |
130 | |
131 | cd.data = (void *)dptr; | |
132 | cd.size = ch[C_FILESIZE]; | |
133 | return cd; /* Found it! */ | |
134 | } | |
135 | len -= (nptr - p); | |
136 | p = nptr; | |
137 | } | |
138 | ||
139 | quit: | |
140 | return cd; | |
141 | } |