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linux-brain/lib/asn1_decoder.c

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X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
/* 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/asn1_decoder.h>
#include <linux/asn1_ber_bytecode.h>
static const unsigned char asn1_op_lengths[ASN1_OP__NR] = {
/* OPC TAG JMP ACT */
[ASN1_OP_MATCH] = 1 + 1,
[ASN1_OP_MATCH_OR_SKIP] = 1 + 1,
[ASN1_OP_MATCH_ACT] = 1 + 1 + 1,
[ASN1_OP_MATCH_ACT_OR_SKIP] = 1 + 1 + 1,
[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_ACT] = 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_ACT] = 1 + 1,
[ASN1_OP_COND_FAIL] = 1,
[ASN1_OP_COMPLETE] = 1,
[ASN1_OP_ACT] = 1 + 1,
ASN.1: Fix actions on CHOICE elements with IMPLICIT tags In an ASN.1 description where there is a CHOICE construct that contains elements with IMPLICIT tags that refer to constructed types, actions to be taken on those elements should be conditional on the corresponding element actually being matched. Currently, however, such actions are performed unconditionally in the middle of processing the CHOICE. For example, look at elements 'b' and 'e' here: A ::= SEQUENCE { CHOICE { b [0] IMPLICIT B ({ do_XXXXXXXXXXXX_b }), c [1] EXPLICIT C ({ do_XXXXXXXXXXXX_c }), d [2] EXPLICIT B ({ do_XXXXXXXXXXXX_d }), e [3] IMPLICIT C ({ do_XXXXXXXXXXXX_e }), f [4] IMPLICIT INTEGER ({ do_XXXXXXXXXXXX_f }) } } ({ do_XXXXXXXXXXXX_A }) B ::= SET OF OBJECT IDENTIFIER ({ do_XXXXXXXXXXXX_oid }) C ::= SET OF INTEGER ({ do_XXXXXXXXXXXX_int }) They each have an action (do_XXXXXXXXXXXX_b and do_XXXXXXXXXXXX_e) that should only be processed if that element is matched. The problem is that there's no easy place to hang the action off in the subclause (type B for element 'b' and type C for element 'e') because subclause opcode sequences can be shared. To fix this, introduce a conditional action opcode(ASN1_OP_MAYBE_ACT) that the decoder only processes if the preceding match was successful. This can be seen in an excerpt from the output of the fixed ASN.1 compiler for the above ASN.1 description: [ 13] = ASN1_OP_COND_MATCH_JUMP_OR_SKIP, // e [ 14] = _tagn(CONT, CONS, 3), [ 15] = _jump_target(45), // --> C [ 16] = ASN1_OP_MAYBE_ACT, [ 17] = _action(ACT_do_XXXXXXXXXXXX_e), In this, if the op at [13] is matched (ie. element 'e' above) then the action at [16] will be performed. However, if the op at [13] doesn't match or is skipped because it is conditional and some previous op matched, then the action at [16] will be ignored. Note that to make this work in the decoder, the ASN1_OP_RETURN op must set the flag to indicate that a match happened. This is necessary because the _jump_target() seen above introduces a subclause (in this case an object of type 'C') which is likely to alter the flag. Setting the flag here is okay because to process a subclause, a match must have happened and caused a jump. This cannot be tested with the code as it stands, but rather affects future code. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 20:54:46 +09:00
[ASN1_OP_MAYBE_ACT] = 1 + 1,
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
[ASN1_OP_RETURN] = 1,
[ASN1_OP_END_SEQ] = 1,
[ASN1_OP_END_SEQ_OF] = 1 + 1,
[ASN1_OP_END_SET] = 1,
[ASN1_OP_END_SET_OF] = 1 + 1,
[ASN1_OP_END_SEQ_ACT] = 1 + 1,
[ASN1_OP_END_SEQ_OF_ACT] = 1 + 1 + 1,
[ASN1_OP_END_SET_ACT] = 1 + 1,
[ASN1_OP_END_SET_OF_ACT] = 1 + 1 + 1,
};
/*
* Find the length of an indefinite length object
X.509: Fix indefinite length element skip error handling asn1_find_indefinite_length() returns an error indicator of -1, which the caller asn1_ber_decoder() places in a size_t (which is usually unsigned) and then checks to see whether it is less than 0 (which it can't be). This can lead to the following warning: lib/asn1_decoder.c:320 asn1_ber_decoder() warn: unsigned 'len' is never less than zero. Instead, asn1_find_indefinite_length() update the caller's idea of the data cursor and length separately from returning the error code. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-10-04 22:21:23 +09:00
* @data: The data buffer
* @datalen: The end of the innermost containing element in the buffer
* @_dp: The data parse cursor (updated before returning)
* @_len: Where to return the size of the element.
* @_errmsg: Where to return a pointer to an error message on error
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
*/
static int asn1_find_indefinite_length(const unsigned char *data, size_t datalen,
X.509: Fix indefinite length element skip error handling asn1_find_indefinite_length() returns an error indicator of -1, which the caller asn1_ber_decoder() places in a size_t (which is usually unsigned) and then checks to see whether it is less than 0 (which it can't be). This can lead to the following warning: lib/asn1_decoder.c:320 asn1_ber_decoder() warn: unsigned 'len' is never less than zero. Instead, asn1_find_indefinite_length() update the caller's idea of the data cursor and length separately from returning the error code. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-10-04 22:21:23 +09:00
size_t *_dp, size_t *_len,
const char **_errmsg)
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
{
unsigned char tag, tmp;
X.509: Fix indefinite length element skip error handling asn1_find_indefinite_length() returns an error indicator of -1, which the caller asn1_ber_decoder() places in a size_t (which is usually unsigned) and then checks to see whether it is less than 0 (which it can't be). This can lead to the following warning: lib/asn1_decoder.c:320 asn1_ber_decoder() warn: unsigned 'len' is never less than zero. Instead, asn1_find_indefinite_length() update the caller's idea of the data cursor and length separately from returning the error code. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-10-04 22:21:23 +09:00
size_t dp = *_dp, len, n;
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
int indef_level = 1;
next_tag:
if (unlikely(datalen - dp < 2)) {
if (datalen == dp)
goto missing_eoc;
goto data_overrun_error;
}
/* Extract a tag from the data */
tag = data[dp++];
if (tag == 0) {
/* It appears to be an EOC. */
if (data[dp++] != 0)
goto invalid_eoc;
X.509: Fix indefinite length element skip error handling asn1_find_indefinite_length() returns an error indicator of -1, which the caller asn1_ber_decoder() places in a size_t (which is usually unsigned) and then checks to see whether it is less than 0 (which it can't be). This can lead to the following warning: lib/asn1_decoder.c:320 asn1_ber_decoder() warn: unsigned 'len' is never less than zero. Instead, asn1_find_indefinite_length() update the caller's idea of the data cursor and length separately from returning the error code. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-10-04 22:21:23 +09:00
if (--indef_level <= 0) {
*_len = dp - *_dp;
*_dp = dp;
return 0;
}
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
goto next_tag;
}
ASN.1: Use the ASN1_LONG_TAG and ASN1_INDEFINITE_LENGTH constants Use the ASN1_LONG_TAG and ASN1_INDEFINITE_LENGTH constants in the ASN.1 general decoder instead of the equivalent numbers. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-12-05 10:25:30 +09:00
if (unlikely((tag & 0x1f) == ASN1_LONG_TAG)) {
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
do {
if (unlikely(datalen - dp < 2))
goto data_overrun_error;
tmp = data[dp++];
} while (tmp & 0x80);
}
/* Extract the length */
len = data[dp++];
ASN.1: Fix an indefinite length skip error Fix an error in asn1_find_indefinite_length() whereby small definite length elements of size 0x7f are incorrecly classified as non-small. Without this fix, an error will be given as the length of the length will be perceived as being very much greater than the maximum supported size. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-10-22 23:05:55 +09:00
if (len <= 0x7f) {
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
dp += len;
goto next_tag;
}
ASN.1: Use the ASN1_LONG_TAG and ASN1_INDEFINITE_LENGTH constants Use the ASN1_LONG_TAG and ASN1_INDEFINITE_LENGTH constants in the ASN.1 general decoder instead of the equivalent numbers. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-12-05 10:25:30 +09:00
if (unlikely(len == ASN1_INDEFINITE_LENGTH)) {
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
/* Indefinite length */
if (unlikely((tag & ASN1_CONS_BIT) == ASN1_PRIM << 5))
goto indefinite_len_primitive;
indef_level++;
goto next_tag;
}
n = len - 0x80;
if (unlikely(n > sizeof(size_t) - 1))
goto length_too_long;
if (unlikely(n > datalen - dp))
goto data_overrun_error;
for (len = 0; n > 0; n--) {
len <<= 8;
len |= data[dp++];
}
dp += len;
goto next_tag;
length_too_long:
*_errmsg = "Unsupported length";
goto error;
indefinite_len_primitive:
*_errmsg = "Indefinite len primitive not permitted";
goto error;
invalid_eoc:
*_errmsg = "Invalid length EOC";
goto error;
data_overrun_error:
*_errmsg = "Data overrun error";
goto error;
missing_eoc:
*_errmsg = "Missing EOC in indefinite len cons";
error:
X.509: Fix indefinite length element skip error handling asn1_find_indefinite_length() returns an error indicator of -1, which the caller asn1_ber_decoder() places in a size_t (which is usually unsigned) and then checks to see whether it is less than 0 (which it can't be). This can lead to the following warning: lib/asn1_decoder.c:320 asn1_ber_decoder() warn: unsigned 'len' is never less than zero. Instead, asn1_find_indefinite_length() update the caller's idea of the data cursor and length separately from returning the error code. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-10-04 22:21:23 +09:00
*_dp = dp;
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
return -1;
}
/**
* asn1_ber_decoder - Decoder BER/DER/CER ASN.1 according to pattern
* @decoder: The decoder definition (produced by asn1_compiler)
* @context: The caller's context (to be passed to the action functions)
* @data: The encoded data
lib/asn1_decoder.c: kernel-doc warning fix Signed-off-by: Fabian Frederick <fabf@skynet.be> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-05 08:12:01 +09:00
* @datalen: The size of the encoded data
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
*
* 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
* allow the caller to retrieve significant data.
*
* LIMITATIONS:
*
* To keep down the amount of stack used by this function, the following limits
* have been imposed:
*
* (1) This won't handle datalen > 65535 without increasing the size of the
* cons stack elements and length_too_long checking.
*
* (2) The stack of constructed types is 10 deep. If the depth of non-leaf
* constructed types exceeds this, the decode will fail.
*
* (3) The SET type (not the SET OF type) isn't really supported as tracking
* what members of the set have been seen is a pain.
*/
int asn1_ber_decoder(const struct asn1_decoder *decoder,
void *context,
const unsigned char *data,
size_t datalen)
{
const unsigned char *machine = decoder->machine;
const asn1_action_t *actions = decoder->actions;
size_t machlen = decoder->machlen;
enum asn1_opcode op;
unsigned char tag = 0, csp = 0, jsp = 0, optag = 0, hdr = 0;
const char *errmsg;
size_t pc = 0, dp = 0, tdp = 0, len = 0;
int ret;
unsigned char flags = 0;
#define FLAG_INDEFINITE_LENGTH 0x01
#define FLAG_MATCHED 0x02
ASN.1: Fix actions on CHOICE elements with IMPLICIT tags In an ASN.1 description where there is a CHOICE construct that contains elements with IMPLICIT tags that refer to constructed types, actions to be taken on those elements should be conditional on the corresponding element actually being matched. Currently, however, such actions are performed unconditionally in the middle of processing the CHOICE. For example, look at elements 'b' and 'e' here: A ::= SEQUENCE { CHOICE { b [0] IMPLICIT B ({ do_XXXXXXXXXXXX_b }), c [1] EXPLICIT C ({ do_XXXXXXXXXXXX_c }), d [2] EXPLICIT B ({ do_XXXXXXXXXXXX_d }), e [3] IMPLICIT C ({ do_XXXXXXXXXXXX_e }), f [4] IMPLICIT INTEGER ({ do_XXXXXXXXXXXX_f }) } } ({ do_XXXXXXXXXXXX_A }) B ::= SET OF OBJECT IDENTIFIER ({ do_XXXXXXXXXXXX_oid }) C ::= SET OF INTEGER ({ do_XXXXXXXXXXXX_int }) They each have an action (do_XXXXXXXXXXXX_b and do_XXXXXXXXXXXX_e) that should only be processed if that element is matched. The problem is that there's no easy place to hang the action off in the subclause (type B for element 'b' and type C for element 'e') because subclause opcode sequences can be shared. To fix this, introduce a conditional action opcode(ASN1_OP_MAYBE_ACT) that the decoder only processes if the preceding match was successful. This can be seen in an excerpt from the output of the fixed ASN.1 compiler for the above ASN.1 description: [ 13] = ASN1_OP_COND_MATCH_JUMP_OR_SKIP, // e [ 14] = _tagn(CONT, CONS, 3), [ 15] = _jump_target(45), // --> C [ 16] = ASN1_OP_MAYBE_ACT, [ 17] = _action(ACT_do_XXXXXXXXXXXX_e), In this, if the op at [13] is matched (ie. element 'e' above) then the action at [16] will be performed. However, if the op at [13] doesn't match or is skipped because it is conditional and some previous op matched, then the action at [16] will be ignored. Note that to make this work in the decoder, the ASN1_OP_RETURN op must set the flag to indicate that a match happened. This is necessary because the _jump_target() seen above introduces a subclause (in this case an object of type 'C') which is likely to alter the flag. Setting the flag here is okay because to process a subclause, a match must have happened and caused a jump. This cannot be tested with the code as it stands, but rather affects future code. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 20:54:46 +09:00
#define FLAG_LAST_MATCHED 0x04 /* Last tag matched */
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
#define FLAG_CONS 0x20 /* Corresponds to CONS bit in the opcode tag
* - ie. whether or not we are going to parse
* a compound type.
*/
#define NR_CONS_STACK 10
unsigned short cons_dp_stack[NR_CONS_STACK];
unsigned short cons_datalen_stack[NR_CONS_STACK];
unsigned char cons_hdrlen_stack[NR_CONS_STACK];
#define NR_JUMP_STACK 10
unsigned char jump_stack[NR_JUMP_STACK];
if (datalen > 65535)
return -EMSGSIZE;
next_op:
pr_debug("next_op: pc=\e[32m%zu\e[m/%zu dp=\e[33m%zu\e[m/%zu C=%d J=%d\n",
pc, machlen, dp, datalen, csp, jsp);
if (unlikely(pc >= machlen))
goto machine_overrun_error;
op = machine[pc];
if (unlikely(pc + asn1_op_lengths[op] > machlen))
goto machine_overrun_error;
/* If this command is meant to match a tag, then do that before
* evaluating the command.
*/
if (op <= ASN1_OP__MATCHES_TAG) {
unsigned char tmp;
/* Skip conditional matches if possible */
if ((op & ASN1_OP_MATCH__COND &&
flags & FLAG_MATCHED) ||
dp == datalen) {
ASN.1: Fix actions on CHOICE elements with IMPLICIT tags In an ASN.1 description where there is a CHOICE construct that contains elements with IMPLICIT tags that refer to constructed types, actions to be taken on those elements should be conditional on the corresponding element actually being matched. Currently, however, such actions are performed unconditionally in the middle of processing the CHOICE. For example, look at elements 'b' and 'e' here: A ::= SEQUENCE { CHOICE { b [0] IMPLICIT B ({ do_XXXXXXXXXXXX_b }), c [1] EXPLICIT C ({ do_XXXXXXXXXXXX_c }), d [2] EXPLICIT B ({ do_XXXXXXXXXXXX_d }), e [3] IMPLICIT C ({ do_XXXXXXXXXXXX_e }), f [4] IMPLICIT INTEGER ({ do_XXXXXXXXXXXX_f }) } } ({ do_XXXXXXXXXXXX_A }) B ::= SET OF OBJECT IDENTIFIER ({ do_XXXXXXXXXXXX_oid }) C ::= SET OF INTEGER ({ do_XXXXXXXXXXXX_int }) They each have an action (do_XXXXXXXXXXXX_b and do_XXXXXXXXXXXX_e) that should only be processed if that element is matched. The problem is that there's no easy place to hang the action off in the subclause (type B for element 'b' and type C for element 'e') because subclause opcode sequences can be shared. To fix this, introduce a conditional action opcode(ASN1_OP_MAYBE_ACT) that the decoder only processes if the preceding match was successful. This can be seen in an excerpt from the output of the fixed ASN.1 compiler for the above ASN.1 description: [ 13] = ASN1_OP_COND_MATCH_JUMP_OR_SKIP, // e [ 14] = _tagn(CONT, CONS, 3), [ 15] = _jump_target(45), // --> C [ 16] = ASN1_OP_MAYBE_ACT, [ 17] = _action(ACT_do_XXXXXXXXXXXX_e), In this, if the op at [13] is matched (ie. element 'e' above) then the action at [16] will be performed. However, if the op at [13] doesn't match or is skipped because it is conditional and some previous op matched, then the action at [16] will be ignored. Note that to make this work in the decoder, the ASN1_OP_RETURN op must set the flag to indicate that a match happened. This is necessary because the _jump_target() seen above introduces a subclause (in this case an object of type 'C') which is likely to alter the flag. Setting the flag here is okay because to process a subclause, a match must have happened and caused a jump. This cannot be tested with the code as it stands, but rather affects future code. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 20:54:46 +09:00
flags &= ~FLAG_LAST_MATCHED;
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
pc += asn1_op_lengths[op];
goto next_op;
}
flags = 0;
hdr = 2;
/* Extract a tag from the data */
if (unlikely(dp >= datalen - 1))
goto data_overrun_error;
tag = data[dp++];
ASN.1: Use the ASN1_LONG_TAG and ASN1_INDEFINITE_LENGTH constants Use the ASN1_LONG_TAG and ASN1_INDEFINITE_LENGTH constants in the ASN.1 general decoder instead of the equivalent numbers. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-12-05 10:25:30 +09:00
if (unlikely((tag & 0x1f) == ASN1_LONG_TAG))
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
goto long_tag_not_supported;
if (op & ASN1_OP_MATCH__ANY) {
pr_debug("- any %02x\n", tag);
} else {
/* Extract the tag from the machine
* - Either CONS or PRIM are permitted in the data if
* CONS is not set in the op stream, otherwise CONS
* is mandatory.
*/
optag = machine[pc + 1];
flags |= optag & FLAG_CONS;
/* Determine whether the tag matched */
tmp = optag ^ tag;
tmp &= ~(optag & ASN1_CONS_BIT);
pr_debug("- match? %02x %02x %02x\n", tag, optag, tmp);
if (tmp != 0) {
/* All odd-numbered tags are MATCH_OR_SKIP. */
if (op & ASN1_OP_MATCH__SKIP) {
pc += asn1_op_lengths[op];
dp--;
goto next_op;
}
goto tag_mismatch;
}
}
flags |= FLAG_MATCHED;
len = data[dp++];
if (len > 0x7f) {
ASN.1: Use the ASN1_LONG_TAG and ASN1_INDEFINITE_LENGTH constants Use the ASN1_LONG_TAG and ASN1_INDEFINITE_LENGTH constants in the ASN.1 general decoder instead of the equivalent numbers. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-12-05 10:25:30 +09:00
if (unlikely(len == ASN1_INDEFINITE_LENGTH)) {
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
/* Indefinite length */
if (unlikely(!(tag & ASN1_CONS_BIT)))
goto indefinite_len_primitive;
flags |= FLAG_INDEFINITE_LENGTH;
if (unlikely(2 > datalen - dp))
goto data_overrun_error;
} else {
int n = len - 0x80;
if (unlikely(n > 2))
goto length_too_long;
if (unlikely(dp >= datalen - n))
goto data_overrun_error;
hdr += n;
for (len = 0; n > 0; n--) {
len <<= 8;
len |= data[dp++];
}
if (unlikely(len > datalen - dp))
goto data_overrun_error;
}
}
if (flags & FLAG_CONS) {
/* For expected compound forms, we stack the positions
* of the start and end of the data.
*/
if (unlikely(csp >= NR_CONS_STACK))
goto cons_stack_overflow;
cons_dp_stack[csp] = dp;
cons_hdrlen_stack[csp] = hdr;
if (!(flags & FLAG_INDEFINITE_LENGTH)) {
cons_datalen_stack[csp] = datalen;
datalen = dp + len;
} else {
cons_datalen_stack[csp] = 0;
}
csp++;
}
pr_debug("- TAG: %02x %zu%s\n",
tag, len, flags & FLAG_CONS ? " CONS" : "");
tdp = dp;
}
/* 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_ANY:
case ASN1_OP_COND_MATCH_OR_SKIP:
case ASN1_OP_COND_MATCH_ANY:
skip_data:
if (!(flags & FLAG_CONS)) {
if (flags & FLAG_INDEFINITE_LENGTH) {
X.509: Fix indefinite length element skip error handling asn1_find_indefinite_length() returns an error indicator of -1, which the caller asn1_ber_decoder() places in a size_t (which is usually unsigned) and then checks to see whether it is less than 0 (which it can't be). This can lead to the following warning: lib/asn1_decoder.c:320 asn1_ber_decoder() warn: unsigned 'len' is never less than zero. Instead, asn1_find_indefinite_length() update the caller's idea of the data cursor and length separately from returning the error code. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-10-04 22:21:23 +09:00
ret = asn1_find_indefinite_length(
data, datalen, &dp, &len, &errmsg);
if (ret < 0)
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
goto error;
X.509: Fix indefinite length element skip error handling asn1_find_indefinite_length() returns an error indicator of -1, which the caller asn1_ber_decoder() places in a size_t (which is usually unsigned) and then checks to see whether it is less than 0 (which it can't be). This can lead to the following warning: lib/asn1_decoder.c:320 asn1_ber_decoder() warn: unsigned 'len' is never less than zero. Instead, asn1_find_indefinite_length() update the caller's idea of the data cursor and length separately from returning the error code. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-10-04 22:21:23 +09:00
} else {
dp += len;
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
}
pr_debug("- LEAF: %zu\n", len);
}
pc += asn1_op_lengths[op];
goto next_op;
case ASN1_OP_MATCH_JUMP:
case ASN1_OP_MATCH_JUMP_OR_SKIP:
case ASN1_OP_COND_MATCH_JUMP_OR_SKIP:
pr_debug("- MATCH_JUMP\n");
if (unlikely(jsp == NR_JUMP_STACK))
goto jump_stack_overflow;
jump_stack[jsp++] = pc + asn1_op_lengths[op];
pc = machine[pc + 2];
goto next_op;
case ASN1_OP_COND_FAIL:
if (unlikely(!(flags & FLAG_MATCHED)))
goto tag_mismatch;
pc += asn1_op_lengths[op];
goto next_op;
case ASN1_OP_COMPLETE:
if (unlikely(jsp != 0 || csp != 0)) {
pr_err("ASN.1 decoder error: Stacks not empty at completion (%u, %u)\n",
jsp, csp);
return -EBADMSG;
}
return 0;
case ASN1_OP_END_SET:
case ASN1_OP_END_SET_ACT:
if (unlikely(!(flags & FLAG_MATCHED)))
goto tag_mismatch;
case ASN1_OP_END_SEQ:
case ASN1_OP_END_SET_OF:
case ASN1_OP_END_SEQ_OF:
case ASN1_OP_END_SEQ_ACT:
case ASN1_OP_END_SET_OF_ACT:
case ASN1_OP_END_SEQ_OF_ACT:
if (unlikely(csp <= 0))
goto cons_stack_underflow;
csp--;
tdp = cons_dp_stack[csp];
hdr = cons_hdrlen_stack[csp];
len = datalen;
datalen = cons_datalen_stack[csp];
pr_debug("- end cons t=%zu dp=%zu l=%zu/%zu\n",
tdp, dp, len, datalen);
if (datalen == 0) {
/* Indefinite length - check for the EOC. */
datalen = len;
if (unlikely(datalen - dp < 2))
goto data_overrun_error;
if (data[dp++] != 0) {
if (op & ASN1_OP_END__OF) {
dp--;
csp++;
pc = machine[pc + 1];
pr_debug("- continue\n");
goto next_op;
}
goto missing_eoc;
}
if (data[dp++] != 0)
goto invalid_eoc;
len = dp - tdp - 2;
} else {
if (dp < len && (op & ASN1_OP_END__OF)) {
datalen = len;
csp++;
pc = machine[pc + 1];
pr_debug("- continue\n");
goto next_op;
}
if (dp != len)
goto cons_length_error;
len -= tdp;
pr_debug("- cons len l=%zu d=%zu\n", len, dp - tdp);
}
if (op & ASN1_OP_END__ACT) {
unsigned char act;
if (op & ASN1_OP_END__OF)
act = machine[pc + 2];
else
act = machine[pc + 1];
ret = actions[act](context, hdr, 0, data + tdp, len);
}
pc += asn1_op_lengths[op];
goto next_op;
ASN.1: Fix actions on CHOICE elements with IMPLICIT tags In an ASN.1 description where there is a CHOICE construct that contains elements with IMPLICIT tags that refer to constructed types, actions to be taken on those elements should be conditional on the corresponding element actually being matched. Currently, however, such actions are performed unconditionally in the middle of processing the CHOICE. For example, look at elements 'b' and 'e' here: A ::= SEQUENCE { CHOICE { b [0] IMPLICIT B ({ do_XXXXXXXXXXXX_b }), c [1] EXPLICIT C ({ do_XXXXXXXXXXXX_c }), d [2] EXPLICIT B ({ do_XXXXXXXXXXXX_d }), e [3] IMPLICIT C ({ do_XXXXXXXXXXXX_e }), f [4] IMPLICIT INTEGER ({ do_XXXXXXXXXXXX_f }) } } ({ do_XXXXXXXXXXXX_A }) B ::= SET OF OBJECT IDENTIFIER ({ do_XXXXXXXXXXXX_oid }) C ::= SET OF INTEGER ({ do_XXXXXXXXXXXX_int }) They each have an action (do_XXXXXXXXXXXX_b and do_XXXXXXXXXXXX_e) that should only be processed if that element is matched. The problem is that there's no easy place to hang the action off in the subclause (type B for element 'b' and type C for element 'e') because subclause opcode sequences can be shared. To fix this, introduce a conditional action opcode(ASN1_OP_MAYBE_ACT) that the decoder only processes if the preceding match was successful. This can be seen in an excerpt from the output of the fixed ASN.1 compiler for the above ASN.1 description: [ 13] = ASN1_OP_COND_MATCH_JUMP_OR_SKIP, // e [ 14] = _tagn(CONT, CONS, 3), [ 15] = _jump_target(45), // --> C [ 16] = ASN1_OP_MAYBE_ACT, [ 17] = _action(ACT_do_XXXXXXXXXXXX_e), In this, if the op at [13] is matched (ie. element 'e' above) then the action at [16] will be performed. However, if the op at [13] doesn't match or is skipped because it is conditional and some previous op matched, then the action at [16] will be ignored. Note that to make this work in the decoder, the ASN1_OP_RETURN op must set the flag to indicate that a match happened. This is necessary because the _jump_target() seen above introduces a subclause (in this case an object of type 'C') which is likely to alter the flag. Setting the flag here is okay because to process a subclause, a match must have happened and caused a jump. This cannot be tested with the code as it stands, but rather affects future code. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 20:54:46 +09:00
case ASN1_OP_MAYBE_ACT:
if (!(flags & FLAG_LAST_MATCHED)) {
pc += asn1_op_lengths[op];
goto next_op;
}
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
case ASN1_OP_ACT:
ret = actions[machine[pc + 1]](context, hdr, tag, data + tdp, len);
ASN.1: Fix actions on CHOICE elements with IMPLICIT tags In an ASN.1 description where there is a CHOICE construct that contains elements with IMPLICIT tags that refer to constructed types, actions to be taken on those elements should be conditional on the corresponding element actually being matched. Currently, however, such actions are performed unconditionally in the middle of processing the CHOICE. For example, look at elements 'b' and 'e' here: A ::= SEQUENCE { CHOICE { b [0] IMPLICIT B ({ do_XXXXXXXXXXXX_b }), c [1] EXPLICIT C ({ do_XXXXXXXXXXXX_c }), d [2] EXPLICIT B ({ do_XXXXXXXXXXXX_d }), e [3] IMPLICIT C ({ do_XXXXXXXXXXXX_e }), f [4] IMPLICIT INTEGER ({ do_XXXXXXXXXXXX_f }) } } ({ do_XXXXXXXXXXXX_A }) B ::= SET OF OBJECT IDENTIFIER ({ do_XXXXXXXXXXXX_oid }) C ::= SET OF INTEGER ({ do_XXXXXXXXXXXX_int }) They each have an action (do_XXXXXXXXXXXX_b and do_XXXXXXXXXXXX_e) that should only be processed if that element is matched. The problem is that there's no easy place to hang the action off in the subclause (type B for element 'b' and type C for element 'e') because subclause opcode sequences can be shared. To fix this, introduce a conditional action opcode(ASN1_OP_MAYBE_ACT) that the decoder only processes if the preceding match was successful. This can be seen in an excerpt from the output of the fixed ASN.1 compiler for the above ASN.1 description: [ 13] = ASN1_OP_COND_MATCH_JUMP_OR_SKIP, // e [ 14] = _tagn(CONT, CONS, 3), [ 15] = _jump_target(45), // --> C [ 16] = ASN1_OP_MAYBE_ACT, [ 17] = _action(ACT_do_XXXXXXXXXXXX_e), In this, if the op at [13] is matched (ie. element 'e' above) then the action at [16] will be performed. However, if the op at [13] doesn't match or is skipped because it is conditional and some previous op matched, then the action at [16] will be ignored. Note that to make this work in the decoder, the ASN1_OP_RETURN op must set the flag to indicate that a match happened. This is necessary because the _jump_target() seen above introduces a subclause (in this case an object of type 'C') which is likely to alter the flag. Setting the flag here is okay because to process a subclause, a match must have happened and caused a jump. This cannot be tested with the code as it stands, but rather affects future code. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 20:54:46 +09:00
if (ret < 0)
return ret;
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
pc += asn1_op_lengths[op];
goto next_op;
case ASN1_OP_RETURN:
if (unlikely(jsp <= 0))
goto jump_stack_underflow;
pc = jump_stack[--jsp];
ASN.1: Fix actions on CHOICE elements with IMPLICIT tags In an ASN.1 description where there is a CHOICE construct that contains elements with IMPLICIT tags that refer to constructed types, actions to be taken on those elements should be conditional on the corresponding element actually being matched. Currently, however, such actions are performed unconditionally in the middle of processing the CHOICE. For example, look at elements 'b' and 'e' here: A ::= SEQUENCE { CHOICE { b [0] IMPLICIT B ({ do_XXXXXXXXXXXX_b }), c [1] EXPLICIT C ({ do_XXXXXXXXXXXX_c }), d [2] EXPLICIT B ({ do_XXXXXXXXXXXX_d }), e [3] IMPLICIT C ({ do_XXXXXXXXXXXX_e }), f [4] IMPLICIT INTEGER ({ do_XXXXXXXXXXXX_f }) } } ({ do_XXXXXXXXXXXX_A }) B ::= SET OF OBJECT IDENTIFIER ({ do_XXXXXXXXXXXX_oid }) C ::= SET OF INTEGER ({ do_XXXXXXXXXXXX_int }) They each have an action (do_XXXXXXXXXXXX_b and do_XXXXXXXXXXXX_e) that should only be processed if that element is matched. The problem is that there's no easy place to hang the action off in the subclause (type B for element 'b' and type C for element 'e') because subclause opcode sequences can be shared. To fix this, introduce a conditional action opcode(ASN1_OP_MAYBE_ACT) that the decoder only processes if the preceding match was successful. This can be seen in an excerpt from the output of the fixed ASN.1 compiler for the above ASN.1 description: [ 13] = ASN1_OP_COND_MATCH_JUMP_OR_SKIP, // e [ 14] = _tagn(CONT, CONS, 3), [ 15] = _jump_target(45), // --> C [ 16] = ASN1_OP_MAYBE_ACT, [ 17] = _action(ACT_do_XXXXXXXXXXXX_e), In this, if the op at [13] is matched (ie. element 'e' above) then the action at [16] will be performed. However, if the op at [13] doesn't match or is skipped because it is conditional and some previous op matched, then the action at [16] will be ignored. Note that to make this work in the decoder, the ASN1_OP_RETURN op must set the flag to indicate that a match happened. This is necessary because the _jump_target() seen above introduces a subclause (in this case an object of type 'C') which is likely to alter the flag. Setting the flag here is okay because to process a subclause, a match must have happened and caused a jump. This cannot be tested with the code as it stands, but rather affects future code. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 20:54:46 +09:00
flags |= FLAG_MATCHED | FLAG_LAST_MATCHED;
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
goto next_op;
default:
break;
}
/* Shouldn't reach here */
ASN.1: Fix actions on CHOICE elements with IMPLICIT tags In an ASN.1 description where there is a CHOICE construct that contains elements with IMPLICIT tags that refer to constructed types, actions to be taken on those elements should be conditional on the corresponding element actually being matched. Currently, however, such actions are performed unconditionally in the middle of processing the CHOICE. For example, look at elements 'b' and 'e' here: A ::= SEQUENCE { CHOICE { b [0] IMPLICIT B ({ do_XXXXXXXXXXXX_b }), c [1] EXPLICIT C ({ do_XXXXXXXXXXXX_c }), d [2] EXPLICIT B ({ do_XXXXXXXXXXXX_d }), e [3] IMPLICIT C ({ do_XXXXXXXXXXXX_e }), f [4] IMPLICIT INTEGER ({ do_XXXXXXXXXXXX_f }) } } ({ do_XXXXXXXXXXXX_A }) B ::= SET OF OBJECT IDENTIFIER ({ do_XXXXXXXXXXXX_oid }) C ::= SET OF INTEGER ({ do_XXXXXXXXXXXX_int }) They each have an action (do_XXXXXXXXXXXX_b and do_XXXXXXXXXXXX_e) that should only be processed if that element is matched. The problem is that there's no easy place to hang the action off in the subclause (type B for element 'b' and type C for element 'e') because subclause opcode sequences can be shared. To fix this, introduce a conditional action opcode(ASN1_OP_MAYBE_ACT) that the decoder only processes if the preceding match was successful. This can be seen in an excerpt from the output of the fixed ASN.1 compiler for the above ASN.1 description: [ 13] = ASN1_OP_COND_MATCH_JUMP_OR_SKIP, // e [ 14] = _tagn(CONT, CONS, 3), [ 15] = _jump_target(45), // --> C [ 16] = ASN1_OP_MAYBE_ACT, [ 17] = _action(ACT_do_XXXXXXXXXXXX_e), In this, if the op at [13] is matched (ie. element 'e' above) then the action at [16] will be performed. However, if the op at [13] doesn't match or is skipped because it is conditional and some previous op matched, then the action at [16] will be ignored. Note that to make this work in the decoder, the ASN1_OP_RETURN op must set the flag to indicate that a match happened. This is necessary because the _jump_target() seen above introduces a subclause (in this case an object of type 'C') which is likely to alter the flag. Setting the flag here is okay because to process a subclause, a match must have happened and caused a jump. This cannot be tested with the code as it stands, but rather affects future code. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
2015-08-05 20:54:46 +09:00
pr_err("ASN.1 decoder error: Found reserved opcode (%u) pc=%zu\n",
op, pc);
X.509: Add an ASN.1 decoder Add an ASN.1 BER/DER/CER decoder. This uses the bytecode from the ASN.1 compiler in the previous patch to inform it as to what to expect to find in the encoded byte stream. The output from the compiler also tells it what functions to call on what tags, thus allowing the caller to retrieve information. The decoder is called as follows: int asn1_decoder(const struct asn1_decoder *decoder, void *context, const unsigned char *data, size_t datalen); The decoder argument points to the bytecode from the ASN.1 compiler. context is the caller's context and is passed to the action functions. data and datalen define the byte stream to be decoded. Note that the decoder is currently limited to datalen being less than 64K. This reduces the amount of stack space used by the decoder because ASN.1 is a nested construct. Similarly, the decoder is limited to a maximum of 10 levels of constructed data outside of a leaf node also in an effort to keep stack usage down. These restrictions can be raised if necessary. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-09-25 01:11:16 +09:00
return -EBADMSG;
data_overrun_error:
errmsg = "Data overrun error";
goto error;
machine_overrun_error:
errmsg = "Machine overrun error";
goto error;
jump_stack_underflow:
errmsg = "Jump stack underflow";
goto error;
jump_stack_overflow:
errmsg = "Jump stack overflow";
goto error;
cons_stack_underflow:
errmsg = "Cons stack underflow";
goto error;
cons_stack_overflow:
errmsg = "Cons stack overflow";
goto error;
cons_length_error:
errmsg = "Cons length error";
goto error;
missing_eoc:
errmsg = "Missing EOC in indefinite len cons";
goto error;
invalid_eoc:
errmsg = "Invalid length EOC";
goto error;
length_too_long:
errmsg = "Unsupported length";
goto error;
indefinite_len_primitive:
errmsg = "Indefinite len primitive not permitted";
goto error;
tag_mismatch:
errmsg = "Unexpected tag";
goto error;
long_tag_not_supported:
errmsg = "Long tag not supported";
error:
pr_debug("\nASN1: %s [m=%zu d=%zu ot=%02x t=%02x l=%zu]\n",
errmsg, pc, dp, optag, tag, len);
return -EBADMSG;
}
EXPORT_SYMBOL_GPL(asn1_ber_decoder);
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