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Diffstat (limited to 'drivers/firmware/google/vpd_decode.c')
-rw-r--r--drivers/firmware/google/vpd_decode.c98
1 files changed, 98 insertions, 0 deletions
diff --git a/drivers/firmware/google/vpd_decode.c b/drivers/firmware/google/vpd_decode.c
new file mode 100644
index 000000000..5c6f2a74f
--- /dev/null
+++ b/drivers/firmware/google/vpd_decode.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * vpd_decode.c
+ *
+ * Google VPD decoding routines.
+ *
+ * Copyright 2017 Google Inc.
+ */
+
+#include "vpd_decode.h"
+
+static int vpd_decode_len(const u32 max_len, const u8 *in,
+ u32 *length, u32 *decoded_len)
+{
+ u8 more;
+ int i = 0;
+
+ if (!length || !decoded_len)
+ return VPD_FAIL;
+
+ *length = 0;
+ do {
+ if (i >= max_len)
+ return VPD_FAIL;
+
+ more = in[i] & 0x80;
+ *length <<= 7;
+ *length |= in[i] & 0x7f;
+ ++i;
+ } while (more);
+
+ *decoded_len = i;
+ return VPD_OK;
+}
+
+static int vpd_decode_entry(const u32 max_len, const u8 *input_buf,
+ u32 *_consumed, const u8 **entry, u32 *entry_len)
+{
+ u32 decoded_len;
+ u32 consumed = *_consumed;
+
+ if (vpd_decode_len(max_len - consumed, &input_buf[consumed],
+ entry_len, &decoded_len) != VPD_OK)
+ return VPD_FAIL;
+ if (max_len - consumed < decoded_len)
+ return VPD_FAIL;
+
+ consumed += decoded_len;
+ *entry = input_buf + consumed;
+
+ /* entry_len is untrusted data and must be checked again. */
+ if (max_len - consumed < *entry_len)
+ return VPD_FAIL;
+
+ consumed += *entry_len;
+ *_consumed = consumed;
+ return VPD_OK;
+}
+
+int vpd_decode_string(const u32 max_len, const u8 *input_buf, u32 *consumed,
+ vpd_decode_callback callback, void *callback_arg)
+{
+ int type;
+ u32 key_len;
+ u32 value_len;
+ const u8 *key;
+ const u8 *value;
+
+ /* type */
+ if (*consumed >= max_len)
+ return VPD_FAIL;
+
+ type = input_buf[*consumed];
+
+ switch (type) {
+ case VPD_TYPE_INFO:
+ case VPD_TYPE_STRING:
+ (*consumed)++;
+
+ if (vpd_decode_entry(max_len, input_buf, consumed, &key,
+ &key_len) != VPD_OK)
+ return VPD_FAIL;
+
+ if (vpd_decode_entry(max_len, input_buf, consumed, &value,
+ &value_len) != VPD_OK)
+ return VPD_FAIL;
+
+ if (type == VPD_TYPE_STRING)
+ return callback(key, key_len, value, value_len,
+ callback_arg);
+ break;
+
+ default:
+ return VPD_FAIL;
+ }
+
+ return VPD_OK;
+}