1*44e33a5aSSean Rhodes // SPDX-License-Identifier: GPL-2.0-only
2*44e33a5aSSean Rhodes /*
3*44e33a5aSSean Rhodes * vpd_decode.c
4*44e33a5aSSean Rhodes *
5*44e33a5aSSean Rhodes * Google VPD decoding routines.
6*44e33a5aSSean Rhodes *
7*44e33a5aSSean Rhodes * Copyright 2017 Google Inc.
8*44e33a5aSSean Rhodes */
9*44e33a5aSSean Rhodes
10*44e33a5aSSean Rhodes #include "vpd_decode.h"
11*44e33a5aSSean Rhodes
vpd_decode_len(const u32 max_len,const u8 * in,u32 * length,u32 * decoded_len)12*44e33a5aSSean Rhodes static int vpd_decode_len(const u32 max_len, const u8 *in,
13*44e33a5aSSean Rhodes u32 *length, u32 *decoded_len)
14*44e33a5aSSean Rhodes {
15*44e33a5aSSean Rhodes u8 more;
16*44e33a5aSSean Rhodes int i = 0;
17*44e33a5aSSean Rhodes
18*44e33a5aSSean Rhodes if (!length || !decoded_len)
19*44e33a5aSSean Rhodes return VPD_FAIL;
20*44e33a5aSSean Rhodes
21*44e33a5aSSean Rhodes *length = 0;
22*44e33a5aSSean Rhodes do {
23*44e33a5aSSean Rhodes if (i >= max_len)
24*44e33a5aSSean Rhodes return VPD_FAIL;
25*44e33a5aSSean Rhodes
26*44e33a5aSSean Rhodes more = in[i] & 0x80;
27*44e33a5aSSean Rhodes *length <<= 7;
28*44e33a5aSSean Rhodes *length |= in[i] & 0x7f;
29*44e33a5aSSean Rhodes ++i;
30*44e33a5aSSean Rhodes } while (more);
31*44e33a5aSSean Rhodes
32*44e33a5aSSean Rhodes *decoded_len = i;
33*44e33a5aSSean Rhodes return VPD_OK;
34*44e33a5aSSean Rhodes }
35*44e33a5aSSean Rhodes
vpd_decode_entry(const u32 max_len,const u8 * input_buf,u32 * _consumed,const u8 ** entry,u32 * entry_len)36*44e33a5aSSean Rhodes static int vpd_decode_entry(const u32 max_len, const u8 *input_buf,
37*44e33a5aSSean Rhodes u32 *_consumed, const u8 **entry, u32 *entry_len)
38*44e33a5aSSean Rhodes {
39*44e33a5aSSean Rhodes u32 decoded_len;
40*44e33a5aSSean Rhodes u32 consumed = *_consumed;
41*44e33a5aSSean Rhodes
42*44e33a5aSSean Rhodes if (vpd_decode_len(max_len - consumed, &input_buf[consumed],
43*44e33a5aSSean Rhodes entry_len, &decoded_len) != VPD_OK)
44*44e33a5aSSean Rhodes return VPD_FAIL;
45*44e33a5aSSean Rhodes if (max_len - consumed < decoded_len)
46*44e33a5aSSean Rhodes return VPD_FAIL;
47*44e33a5aSSean Rhodes
48*44e33a5aSSean Rhodes consumed += decoded_len;
49*44e33a5aSSean Rhodes *entry = input_buf + consumed;
50*44e33a5aSSean Rhodes
51*44e33a5aSSean Rhodes /* entry_len is untrusted data and must be checked again. */
52*44e33a5aSSean Rhodes if (max_len - consumed < *entry_len)
53*44e33a5aSSean Rhodes return VPD_FAIL;
54*44e33a5aSSean Rhodes
55*44e33a5aSSean Rhodes consumed += *entry_len;
56*44e33a5aSSean Rhodes *_consumed = consumed;
57*44e33a5aSSean Rhodes return VPD_OK;
58*44e33a5aSSean Rhodes }
59*44e33a5aSSean Rhodes
vpd_decode_string(const u32 max_len,const u8 * input_buf,u32 * consumed,vpd_decode_callback callback,void * callback_arg)60*44e33a5aSSean Rhodes int vpd_decode_string(const u32 max_len, const u8 *input_buf, u32 *consumed,
61*44e33a5aSSean Rhodes vpd_decode_callback callback, void *callback_arg)
62*44e33a5aSSean Rhodes {
63*44e33a5aSSean Rhodes int type;
64*44e33a5aSSean Rhodes u32 key_len;
65*44e33a5aSSean Rhodes u32 value_len;
66*44e33a5aSSean Rhodes const u8 *key;
67*44e33a5aSSean Rhodes const u8 *value;
68*44e33a5aSSean Rhodes
69*44e33a5aSSean Rhodes /* type */
70*44e33a5aSSean Rhodes if (*consumed >= max_len)
71*44e33a5aSSean Rhodes return VPD_FAIL;
72*44e33a5aSSean Rhodes
73*44e33a5aSSean Rhodes type = input_buf[*consumed];
74*44e33a5aSSean Rhodes
75*44e33a5aSSean Rhodes switch (type) {
76*44e33a5aSSean Rhodes case VPD_TYPE_INFO:
77*44e33a5aSSean Rhodes case VPD_TYPE_STRING:
78*44e33a5aSSean Rhodes (*consumed)++;
79*44e33a5aSSean Rhodes
80*44e33a5aSSean Rhodes if (vpd_decode_entry(max_len, input_buf, consumed, &key,
81*44e33a5aSSean Rhodes &key_len) != VPD_OK)
82*44e33a5aSSean Rhodes return VPD_FAIL;
83*44e33a5aSSean Rhodes
84*44e33a5aSSean Rhodes if (vpd_decode_entry(max_len, input_buf, consumed, &value,
85*44e33a5aSSean Rhodes &value_len) != VPD_OK)
86*44e33a5aSSean Rhodes return VPD_FAIL;
87*44e33a5aSSean Rhodes
88*44e33a5aSSean Rhodes if (type == VPD_TYPE_STRING)
89*44e33a5aSSean Rhodes return callback(key, key_len, value, value_len,
90*44e33a5aSSean Rhodes callback_arg);
91*44e33a5aSSean Rhodes break;
92*44e33a5aSSean Rhodes
93*44e33a5aSSean Rhodes default:
94*44e33a5aSSean Rhodes return VPD_FAIL;
95*44e33a5aSSean Rhodes }
96*44e33a5aSSean Rhodes
97*44e33a5aSSean Rhodes return VPD_OK;
98*44e33a5aSSean Rhodes }
99