src/drivers/vpd/vpd_decode.c

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