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-rw-r--r--lib/asn1_decoder.c111
1 files changed, 73 insertions, 38 deletions
diff --git a/lib/asn1_decoder.c b/lib/asn1_decoder.c
index 11b9b01fda6b..5738ae286b41 100644
--- a/lib/asn1_decoder.c
+++ b/lib/asn1_decoder.c
@@ -1,17 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
/* Decoder for ASN.1 BER/DER/CER encoded bytestream
*
* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public Licence
- * as published by the Free Software Foundation; either version
- * 2 of the Licence, or (at your option) any later version.
*/
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/errno.h>
+#include <linux/module.h>
#include <linux/asn1_decoder.h>
#include <linux/asn1_ber_bytecode.h>
@@ -24,15 +21,20 @@ static const unsigned char asn1_op_lengths[ASN1_OP__NR] = {
[ASN1_OP_MATCH_JUMP] = 1 + 1 + 1,
[ASN1_OP_MATCH_JUMP_OR_SKIP] = 1 + 1 + 1,
[ASN1_OP_MATCH_ANY] = 1,
+ [ASN1_OP_MATCH_ANY_OR_SKIP] = 1,
[ASN1_OP_MATCH_ANY_ACT] = 1 + 1,
+ [ASN1_OP_MATCH_ANY_ACT_OR_SKIP] = 1 + 1,
[ASN1_OP_COND_MATCH_OR_SKIP] = 1 + 1,
[ASN1_OP_COND_MATCH_ACT_OR_SKIP] = 1 + 1 + 1,
[ASN1_OP_COND_MATCH_JUMP_OR_SKIP] = 1 + 1 + 1,
[ASN1_OP_COND_MATCH_ANY] = 1,
+ [ASN1_OP_COND_MATCH_ANY_OR_SKIP] = 1,
[ASN1_OP_COND_MATCH_ANY_ACT] = 1 + 1,
+ [ASN1_OP_COND_MATCH_ANY_ACT_OR_SKIP] = 1 + 1,
[ASN1_OP_COND_FAIL] = 1,
[ASN1_OP_COMPLETE] = 1,
[ASN1_OP_ACT] = 1 + 1,
+ [ASN1_OP_MAYBE_ACT] = 1 + 1,
[ASN1_OP_RETURN] = 1,
[ASN1_OP_END_SEQ] = 1,
[ASN1_OP_END_SEQ_OF] = 1 + 1,
@@ -69,7 +71,7 @@ next_tag:
/* Extract a tag from the data */
tag = data[dp++];
- if (tag == 0) {
+ if (tag == ASN1_EOC) {
/* It appears to be an EOC. */
if (data[dp++] != 0)
goto invalid_eoc;
@@ -91,10 +93,8 @@ next_tag:
/* Extract the length */
len = data[dp++];
- if (len <= 0x7f) {
- dp += len;
- goto next_tag;
- }
+ if (len <= 0x7f)
+ goto check_length;
if (unlikely(len == ASN1_INDEFINITE_LENGTH)) {
/* Indefinite length */
@@ -105,14 +105,18 @@ next_tag:
}
n = len - 0x80;
- if (unlikely(n > sizeof(size_t) - 1))
+ if (unlikely(n > sizeof(len) - 1))
goto length_too_long;
if (unlikely(n > datalen - dp))
goto data_overrun_error;
- for (len = 0; n > 0; n--) {
+ len = 0;
+ for (; n > 0; n--) {
len <<= 8;
len |= data[dp++];
}
+check_length:
+ if (len > datalen - dp)
+ goto data_overrun_error;
dp += len;
goto next_tag;
@@ -140,7 +144,7 @@ error:
* @decoder: The decoder definition (produced by asn1_compiler)
* @context: The caller's context (to be passed to the action functions)
* @data: The encoded data
- * @datasize: The size of the encoded data
+ * @datalen: The size of the encoded data
*
* Decode BER/DER/CER encoded ASN.1 data according to a bytecode pattern
* produced by asn1_compiler. Action functions are called on marked tags to
@@ -177,6 +181,7 @@ int asn1_ber_decoder(const struct asn1_decoder *decoder,
unsigned char flags = 0;
#define FLAG_INDEFINITE_LENGTH 0x01
#define FLAG_MATCHED 0x02
+#define FLAG_LAST_MATCHED 0x04 /* Last tag matched */
#define FLAG_CONS 0x20 /* Corresponds to CONS bit in the opcode tag
* - ie. whether or not we are going to parse
* a compound type.
@@ -208,9 +213,9 @@ next_op:
unsigned char tmp;
/* Skip conditional matches if possible */
- if ((op & ASN1_OP_MATCH__COND &&
- flags & FLAG_MATCHED) ||
- dp == datalen) {
+ if ((op & ASN1_OP_MATCH__COND && flags & FLAG_MATCHED) ||
+ (op & ASN1_OP_MATCH__SKIP && dp == datalen)) {
+ flags &= ~FLAG_LAST_MATCHED;
pc += asn1_op_lengths[op];
goto next_op;
}
@@ -219,7 +224,7 @@ next_op:
hdr = 2;
/* Extract a tag from the data */
- if (unlikely(dp >= datalen - 1))
+ if (unlikely(datalen - dp < 2))
goto data_overrun_error;
tag = data[dp++];
if (unlikely((tag & 0x1f) == ASN1_LONG_TAG))
@@ -265,7 +270,7 @@ next_op:
int n = len - 0x80;
if (unlikely(n > 2))
goto length_too_long;
- if (unlikely(dp >= datalen - n))
+ if (unlikely(n > datalen - dp))
goto data_overrun_error;
hdr += n;
for (len = 0; n > 0; n--) {
@@ -275,6 +280,9 @@ next_op:
if (unlikely(len > datalen - dp))
goto data_overrun_error;
}
+ } else {
+ if (unlikely(len > datalen - dp))
+ goto data_overrun_error;
}
if (flags & FLAG_CONS) {
@@ -301,38 +309,47 @@ next_op:
/* Decide how to handle the operation */
switch (op) {
- case ASN1_OP_MATCH_ANY_ACT:
- case ASN1_OP_COND_MATCH_ANY_ACT:
- ret = actions[machine[pc + 1]](context, hdr, tag, data + dp, len);
- if (ret < 0)
- return ret;
- goto skip_data;
-
- case ASN1_OP_MATCH_ACT:
- case ASN1_OP_MATCH_ACT_OR_SKIP:
- case ASN1_OP_COND_MATCH_ACT_OR_SKIP:
- ret = actions[machine[pc + 2]](context, hdr, tag, data + dp, len);
- if (ret < 0)
- return ret;
- goto skip_data;
-
case ASN1_OP_MATCH:
case ASN1_OP_MATCH_OR_SKIP:
+ case ASN1_OP_MATCH_ACT:
+ case ASN1_OP_MATCH_ACT_OR_SKIP:
case ASN1_OP_MATCH_ANY:
+ case ASN1_OP_MATCH_ANY_OR_SKIP:
+ case ASN1_OP_MATCH_ANY_ACT:
+ case ASN1_OP_MATCH_ANY_ACT_OR_SKIP:
case ASN1_OP_COND_MATCH_OR_SKIP:
+ case ASN1_OP_COND_MATCH_ACT_OR_SKIP:
case ASN1_OP_COND_MATCH_ANY:
- skip_data:
+ case ASN1_OP_COND_MATCH_ANY_OR_SKIP:
+ case ASN1_OP_COND_MATCH_ANY_ACT:
+ case ASN1_OP_COND_MATCH_ANY_ACT_OR_SKIP:
+
if (!(flags & FLAG_CONS)) {
if (flags & FLAG_INDEFINITE_LENGTH) {
+ size_t tmp = dp;
+
ret = asn1_find_indefinite_length(
- data, datalen, &dp, &len, &errmsg);
+ data, datalen, &tmp, &len, &errmsg);
if (ret < 0)
goto error;
- } else {
- dp += len;
}
pr_debug("- LEAF: %zu\n", len);
}
+
+ if (op & ASN1_OP_MATCH__ACT) {
+ unsigned char act;
+
+ if (op & ASN1_OP_MATCH__ANY)
+ act = machine[pc + 1];
+ else
+ act = machine[pc + 2];
+ ret = actions[act](context, hdr, tag, data + dp, len);
+ if (ret < 0)
+ return ret;
+ }
+
+ if (!(flags & FLAG_CONS))
+ dp += len;
pc += asn1_op_lengths[op];
goto next_op;
@@ -364,6 +381,8 @@ next_op:
case ASN1_OP_END_SET_ACT:
if (unlikely(!(flags & FLAG_MATCHED)))
goto tag_mismatch;
+ fallthrough;
+
case ASN1_OP_END_SEQ:
case ASN1_OP_END_SET_OF:
case ASN1_OP_END_SEQ_OF:
@@ -418,12 +437,23 @@ next_op:
else
act = machine[pc + 1];
ret = actions[act](context, hdr, 0, data + tdp, len);
+ if (ret < 0)
+ return ret;
}
pc += asn1_op_lengths[op];
goto next_op;
+ case ASN1_OP_MAYBE_ACT:
+ if (!(flags & FLAG_LAST_MATCHED)) {
+ pc += asn1_op_lengths[op];
+ goto next_op;
+ }
+ fallthrough;
+
case ASN1_OP_ACT:
ret = actions[machine[pc + 1]](context, hdr, tag, data + tdp, len);
+ if (ret < 0)
+ return ret;
pc += asn1_op_lengths[op];
goto next_op;
@@ -431,6 +461,7 @@ next_op:
if (unlikely(jsp <= 0))
goto jump_stack_underflow;
pc = jump_stack[--jsp];
+ flags |= FLAG_MATCHED | FLAG_LAST_MATCHED;
goto next_op;
default:
@@ -438,7 +469,8 @@ next_op:
}
/* Shouldn't reach here */
- pr_err("ASN.1 decoder error: Found reserved opcode (%u)\n", op);
+ pr_err("ASN.1 decoder error: Found reserved opcode (%u) pc=%zu\n",
+ op, pc);
return -EBADMSG;
data_overrun_error:
@@ -485,3 +517,6 @@ error:
return -EBADMSG;
}
EXPORT_SYMBOL_GPL(asn1_ber_decoder);
+
+MODULE_DESCRIPTION("Decoder for ASN.1 BER/DER/CER encoded bytestream");
+MODULE_LICENSE("GPL");
generated by cgit (git 2.34.1) at 2025-12-21 21:13:45 +0000