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