[J-u-boot.git] / lib / asn1_decoder.c

// 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 ([email protected])
 */

#ifdef __UBOOT__
#include <log.h>
#include <linux/compat.h>
#include <linux/printk.h>
#else
#include <linux/export.h>
#endif
#include <linux/kernel.h>
#include <linux/errno.h>
#ifndef __UBOOT__
#include <linux/module.h>
#endif
#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_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,
	[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
 * @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
 */
static int asn1_find_indefinite_length(const unsigned char *data, size_t datalen,
				       size_t *_dp, size_t *_len,
				       const char **_errmsg)
{
	unsigned char tag, tmp;
	size_t dp = *_dp, len, n;
	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 == ASN1_EOC) {
		/* It appears to be an EOC. */
		if (data[dp++] != 0)
			goto invalid_eoc;
		if (--indef_level <= 0) {
			*_len = dp - *_dp;
			*_dp = dp;
			return 0;
		}
		goto next_tag;
	}

	if (unlikely((tag & 0x1f) == ASN1_LONG_TAG)) {
		do {
			if (unlikely(datalen - dp < 2))
				goto data_overrun_error;
			tmp = data[dp++];
		} while (tmp & 0x80);
	}

	/* Extract the length */
	len = data[dp++];
	if (len <= 0x7f)
		goto check_length;

	if (unlikely(len == ASN1_INDEFINITE_LENGTH)) {
		/* 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(len) - 1))
		goto length_too_long;
	if (unlikely(n > datalen - dp))
		goto data_overrun_error;
	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;

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:
	*_dp = dp;
	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
 * @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
 * 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
#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.
				      */

#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) ||
		    (op & ASN1_OP_MATCH__SKIP && dp == datalen)) {
			flags &= ~FLAG_LAST_MATCHED;
			pc += asn1_op_lengths[op];
			goto next_op;
		}

		flags = 0;
		hdr = 2;

		/* Extract a tag from the data */
		if (unlikely(datalen - dp < 2))
			goto data_overrun_error;
		tag = data[dp++];
		if (unlikely((tag & 0x1f) == ASN1_LONG_TAG))
			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) {
			if (unlikely(len == ASN1_INDEFINITE_LENGTH)) {
				/* 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(n > datalen - dp))
					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;
			}
		} else {
			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:
	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:
	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, &tmp, &len, &errmsg);
				if (ret < 0)
					goto error;
			}
			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;

	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;
		/* fall through */

	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);
			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;
		}
		/* fall through */

	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;

	case ASN1_OP_RETURN:
		if (unlikely(jsp <= 0))
			goto jump_stack_underflow;
		pc = jump_stack[--jsp];
		flags |= FLAG_MATCHED | FLAG_LAST_MATCHED;
		goto next_op;

	default:
		break;
	}

	/* Shouldn't reach here */
	pr_err("ASN.1 decoder error: Found reserved opcode (%u) pc=%zu\n",
	       op, pc);
	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);

MODULE_LICENSE("GPL");
Commit	Line	Data
ab8a0e06 AT	1	// SPDX-License-Identifier: GPL-2.0-or-later
	2	/* Decoder for ASN.1 BER/DER/CER encoded bytestream
	3	*
	4	* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
	5	* Written by David Howells ([email protected])
	6	*/
	7
	8	#ifdef __UBOOT__
f7ae49fc	9	#include <log.h>
ab8a0e06	10	#include <linux/compat.h>
1e94b46f	11	#include <linux/printk.h>
ab8a0e06 AT	12	#else
	13	#include <linux/export.h>
	14	#endif
	15	#include <linux/kernel.h>
	16	#include <linux/errno.h>
	17	#ifndef __UBOOT__
	18	#include <linux/module.h>
	19	#endif
	20	#include <linux/asn1_decoder.h>
	21	#include <linux/asn1_ber_bytecode.h>
	22
	23	static const unsigned char asn1_op_lengths[ASN1_OP__NR] = {
	24	/* OPC TAG JMP ACT */
	25	[ASN1_OP_MATCH] = 1 + 1,
	26	[ASN1_OP_MATCH_OR_SKIP] = 1 + 1,
	27	[ASN1_OP_MATCH_ACT] = 1 + 1 + 1,
	28	[ASN1_OP_MATCH_ACT_OR_SKIP] = 1 + 1 + 1,
	29	[ASN1_OP_MATCH_JUMP] = 1 + 1 + 1,
	30	[ASN1_OP_MATCH_JUMP_OR_SKIP] = 1 + 1 + 1,
	31	[ASN1_OP_MATCH_ANY] = 1,
	32	[ASN1_OP_MATCH_ANY_OR_SKIP] = 1,
	33	[ASN1_OP_MATCH_ANY_ACT] = 1 + 1,
	34	[ASN1_OP_MATCH_ANY_ACT_OR_SKIP] = 1 + 1,
	35	[ASN1_OP_COND_MATCH_OR_SKIP] = 1 + 1,
	36	[ASN1_OP_COND_MATCH_ACT_OR_SKIP] = 1 + 1 + 1,
	37	[ASN1_OP_COND_MATCH_JUMP_OR_SKIP] = 1 + 1 + 1,
	38	[ASN1_OP_COND_MATCH_ANY] = 1,
	39	[ASN1_OP_COND_MATCH_ANY_OR_SKIP] = 1,
	40	[ASN1_OP_COND_MATCH_ANY_ACT] = 1 + 1,
	41	[ASN1_OP_COND_MATCH_ANY_ACT_OR_SKIP] = 1 + 1,
	42	[ASN1_OP_COND_FAIL] = 1,
	43	[ASN1_OP_COMPLETE] = 1,
	44	[ASN1_OP_ACT] = 1 + 1,
	45	[ASN1_OP_MAYBE_ACT] = 1 + 1,
	46	[ASN1_OP_RETURN] = 1,
	47	[ASN1_OP_END_SEQ] = 1,
	48	[ASN1_OP_END_SEQ_OF] = 1 + 1,
	49	[ASN1_OP_END_SET] = 1,
	50	[ASN1_OP_END_SET_OF] = 1 + 1,
	51	[ASN1_OP_END_SEQ_ACT] = 1 + 1,
	52	[ASN1_OP_END_SEQ_OF_ACT] = 1 + 1 + 1,
	53	[ASN1_OP_END_SET_ACT] = 1 + 1,
	54	[ASN1_OP_END_SET_OF_ACT] = 1 + 1 + 1,
	55	};
	56
	57	/*
	58	* Find the length of an indefinite length object
	59	* @data: The data buffer
	60	* @datalen: The end of the innermost containing element in the buffer
	61	* @_dp: The data parse cursor (updated before returning)
	62	* @_len: Where to return the size of the element.
	63	* @_errmsg: Where to return a pointer to an error message on error
	64	*/
	65	static int asn1_find_indefinite_length(const unsigned char *data, size_t datalen,
	66	size_t _dp, size_t _len,
	67	const char **_errmsg)
	68	{
	69	unsigned char tag, tmp;
	70	size_t dp = *_dp, len, n;
	71	int indef_level = 1;
	72
	73	next_tag:
	74	if (unlikely(datalen - dp < 2)) {
	75	if (datalen == dp)
76	goto missing_eoc;
77	goto data_overrun_error;
78	}
79
80	/* Extract a tag from the data */
81	tag = data[dp++];
82	if (tag == ASN1_EOC) {
83	/* It appears to be an EOC. */
84	if (data[dp++] != 0)
85	goto invalid_eoc;
86	if (--indef_level <= 0) {
87	_len = dp - _dp;
88	*_dp = dp;
89	return 0;
90	}
91	goto next_tag;
92	}
93
94	if (unlikely((tag & 0x1f) == ASN1_LONG_TAG)) {
95	do {
96	if (unlikely(datalen - dp < 2))
97	goto data_overrun_error;
98	tmp = data[dp++];
99	} while (tmp & 0x80);
100	}
101
102	/* Extract the length */
103	len = data[dp++];
104	if (len <= 0x7f)
105	goto check_length;
106
107	if (unlikely(len == ASN1_INDEFINITE_LENGTH)) {
108	/* Indefinite length */
109	if (unlikely((tag & ASN1_CONS_BIT) == ASN1_PRIM << 5))
110	goto indefinite_len_primitive;
111	indef_level++;
112	goto next_tag;
113	}
114
115	n = len - 0x80;
116	if (unlikely(n > sizeof(len) - 1))
117	goto length_too_long;
118	if (unlikely(n > datalen - dp))
119	goto data_overrun_error;
120	len = 0;
121	for (; n > 0; n--) {
122	len <<= 8;
123	len \|= data[dp++];
124	}
125	check_length:
126	if (len > datalen - dp)
127	goto data_overrun_error;
128	dp += len;
129	goto next_tag;
130
131	length_too_long:
132	*_errmsg = "Unsupported length";
133	goto error;
134	indefinite_len_primitive:
135	*_errmsg = "Indefinite len primitive not permitted";
136	goto error;
137	invalid_eoc:
138	*_errmsg = "Invalid length EOC";
139	goto error;
140	data_overrun_error:
141	*_errmsg = "Data overrun error";
142	goto error;
143	missing_eoc:
144	*_errmsg = "Missing EOC in indefinite len cons";
145	error:
146	*_dp = dp;
147	return -1;
148	}
149
150	/**
151	* asn1_ber_decoder - Decoder BER/DER/CER ASN.1 according to pattern
152	* @decoder: The decoder definition (produced by asn1_compiler)
153	* @context: The caller's context (to be passed to the action functions)
154	* @data: The encoded data
155	* @datalen: The size of the encoded data
156	*
157	* Decode BER/DER/CER encoded ASN.1 data according to a bytecode pattern
158	* produced by asn1_compiler. Action functions are called on marked tags to
159	* allow the caller to retrieve significant data.
160	*
161	* LIMITATIONS:
162	*
163	* To keep down the amount of stack used by this function, the following limits
164	* have been imposed:
165	*
166	* (1) This won't handle datalen > 65535 without increasing the size of the
167	* cons stack elements and length_too_long checking.
168	*
169	* (2) The stack of constructed types is 10 deep. If the depth of non-leaf
170	* constructed types exceeds this, the decode will fail.
171	*
172	* (3) The SET type (not the SET OF type) isn't really supported as tracking
173	* what members of the set have been seen is a pain.
174	*/
175	int asn1_ber_decoder(const struct asn1_decoder *decoder,
176	void *context,
177	const unsigned char *data,
178	size_t datalen)
179	{
180	const unsigned char *machine = decoder->machine;
181	const asn1_action_t *actions = decoder->actions;
182	size_t machlen = decoder->machlen;
183	enum asn1_opcode op;
184	unsigned char tag = 0, csp = 0, jsp = 0, optag = 0, hdr = 0;
185	const char *errmsg;
186	size_t pc = 0, dp = 0, tdp = 0, len = 0;
187	int ret;
188
189	unsigned char flags = 0;
190	#define FLAG_INDEFINITE_LENGTH 0x01
191	#define FLAG_MATCHED 0x02
192	#define FLAG_LAST_MATCHED 0x04 /* Last tag matched */
193	#define FLAG_CONS 0x20 /* Corresponds to CONS bit in the opcode tag
194	* - ie. whether or not we are going to parse
195	* a compound type.
196	*/
197
198	#define NR_CONS_STACK 10
199	unsigned short cons_dp_stack[NR_CONS_STACK];
200	unsigned short cons_datalen_stack[NR_CONS_STACK];
201	unsigned char cons_hdrlen_stack[NR_CONS_STACK];
202	#define NR_JUMP_STACK 10
203	unsigned char jump_stack[NR_JUMP_STACK];
204
205	if (datalen > 65535)
206	return -EMSGSIZE;
207
208	next_op:
209	pr_debug("next_op: pc=\e[32m%zu\e[m/%zu dp=\e[33m%zu\e[m/%zu C=%d J=%d\n",
210	pc, machlen, dp, datalen, csp, jsp);
211	if (unlikely(pc >= machlen))
212	goto machine_overrun_error;
213	op = machine[pc];
214	if (unlikely(pc + asn1_op_lengths[op] > machlen))
215	goto machine_overrun_error;
216
217	/* If this command is meant to match a tag, then do that before
218	* evaluating the command.
219	*/
220	if (op <= ASN1_OP__MATCHES_TAG) {
221	unsigned char tmp;
222
223	/* Skip conditional matches if possible */
224	if ((op & ASN1_OP_MATCH__COND && flags & FLAG_MATCHED) \|\|
225	(op & ASN1_OP_MATCH__SKIP && dp == datalen)) {
226	flags &= ~FLAG_LAST_MATCHED;
227	pc += asn1_op_lengths[op];
228	goto next_op;
229	}
230
231	flags = 0;
232	hdr = 2;
233
234	/* Extract a tag from the data */
235	if (unlikely(datalen - dp < 2))
236	goto data_overrun_error;
237	tag = data[dp++];
238	if (unlikely((tag & 0x1f) == ASN1_LONG_TAG))
239	goto long_tag_not_supported;
240
241	if (op & ASN1_OP_MATCH__ANY) {
242	pr_debug("- any %02x\n", tag);
243	} else {
244	/* Extract the tag from the machine
245	* - Either CONS or PRIM are permitted in the data if
246	* CONS is not set in the op stream, otherwise CONS
247	* is mandatory.
248	*/
249	optag = machine[pc + 1];
250	flags \|= optag & FLAG_CONS;
251
252	/* Determine whether the tag matched */
253	tmp = optag ^ tag;
254	tmp &= ~(optag & ASN1_CONS_BIT);
255	pr_debug("- match? %02x %02x %02x\n", tag, optag, tmp);
256	if (tmp != 0) {
257	/* All odd-numbered tags are MATCH_OR_SKIP. */
258	if (op & ASN1_OP_MATCH__SKIP) {
259	pc += asn1_op_lengths[op];
260	dp--;
261	goto next_op;
262	}
263	goto tag_mismatch;
264	}
265	}
266	flags \|= FLAG_MATCHED;
267
268	len = data[dp++];
269	if (len > 0x7f) {
270	if (unlikely(len == ASN1_INDEFINITE_LENGTH)) {
271	/* Indefinite length */
272	if (unlikely(!(tag & ASN1_CONS_BIT)))
273	goto indefinite_len_primitive;
274	flags \|= FLAG_INDEFINITE_LENGTH;
275	if (unlikely(2 > datalen - dp))
276	goto data_overrun_error;
277	} else {
278	int n = len - 0x80;
279	if (unlikely(n > 2))
280	goto length_too_long;
281	if (unlikely(n > datalen - dp))
282	goto data_overrun_error;
283	hdr += n;
284	for (len = 0; n > 0; n--) {
285	len <<= 8;
286	len \|= data[dp++];
287	}
288	if (unlikely(len > datalen - dp))
289	goto data_overrun_error;
290	}
291	} else {
292	if (unlikely(len > datalen - dp))
293	goto data_overrun_error;
294	}
295
296	if (flags & FLAG_CONS) {
297	/* For expected compound forms, we stack the positions
298	* of the start and end of the data.
299	*/
300	if (unlikely(csp >= NR_CONS_STACK))
301	goto cons_stack_overflow;
302	cons_dp_stack[csp] = dp;
303	cons_hdrlen_stack[csp] = hdr;
304	if (!(flags & FLAG_INDEFINITE_LENGTH)) {
305	cons_datalen_stack[csp] = datalen;
306	datalen = dp + len;
307	} else {
308	cons_datalen_stack[csp] = 0;
309	}
310	csp++;
311	}
312
313	pr_debug("- TAG: %02x %zu%s\n",
314	tag, len, flags & FLAG_CONS ? " CONS" : "");
315	tdp = dp;
316	}
317
318	/* Decide how to handle the operation */
319	switch (op) {
320	case ASN1_OP_MATCH:
321	case ASN1_OP_MATCH_OR_SKIP:
322	case ASN1_OP_MATCH_ACT:
323	case ASN1_OP_MATCH_ACT_OR_SKIP:
324	case ASN1_OP_MATCH_ANY:
325	case ASN1_OP_MATCH_ANY_OR_SKIP:
326	case ASN1_OP_MATCH_ANY_ACT:
327	case ASN1_OP_MATCH_ANY_ACT_OR_SKIP:
328	case ASN1_OP_COND_MATCH_OR_SKIP:
329	case ASN1_OP_COND_MATCH_ACT_OR_SKIP:
330	case ASN1_OP_COND_MATCH_ANY:
331	case ASN1_OP_COND_MATCH_ANY_OR_SKIP:
332	case ASN1_OP_COND_MATCH_ANY_ACT:
333	case ASN1_OP_COND_MATCH_ANY_ACT_OR_SKIP:
334
335	if (!(flags & FLAG_CONS)) {
336	if (flags & FLAG_INDEFINITE_LENGTH) {
337	size_t tmp = dp;
338
339	ret = asn1_find_indefinite_length(
340	data, datalen, &tmp, &len, &errmsg);
341	if (ret < 0)
342	goto error;
343	}
344	pr_debug("- LEAF: %zu\n", len);
345	}
346
347	if (op & ASN1_OP_MATCH__ACT) {
348	unsigned char act;
349
350	if (op & ASN1_OP_MATCH__ANY)
351	act = machine[pc + 1];
352	else
353	act = machine[pc + 2];
354	ret = actions[act](context, hdr, tag, data + dp, len);
355	if (ret < 0)
356	return ret;
357	}
358
359	if (!(flags & FLAG_CONS))
360	dp += len;
361	pc += asn1_op_lengths[op];
362	goto next_op;
363
364	case ASN1_OP_MATCH_JUMP:
365	case ASN1_OP_MATCH_JUMP_OR_SKIP:
366	case ASN1_OP_COND_MATCH_JUMP_OR_SKIP:
367	pr_debug("- MATCH_JUMP\n");
368	if (unlikely(jsp == NR_JUMP_STACK))
369	goto jump_stack_overflow;
370	jump_stack[jsp++] = pc + asn1_op_lengths[op];
371	pc = machine[pc + 2];
372	goto next_op;
373
374	case ASN1_OP_COND_FAIL:
375	if (unlikely(!(flags & FLAG_MATCHED)))
376	goto tag_mismatch;
377	pc += asn1_op_lengths[op];
378	goto next_op;
379
380	case ASN1_OP_COMPLETE:
381	if (unlikely(jsp != 0 \|\| csp != 0)) {
382	pr_err("ASN.1 decoder error: Stacks not empty at completion (%u, %u)\n",
383	jsp, csp);
384	return -EBADMSG;
385	}
386	return 0;
387
388	case ASN1_OP_END_SET:
389	case ASN1_OP_END_SET_ACT:
390	if (unlikely(!(flags & FLAG_MATCHED)))
391	goto tag_mismatch;
392	/* fall through */
393
394	case ASN1_OP_END_SEQ:
395	case ASN1_OP_END_SET_OF:
396	case ASN1_OP_END_SEQ_OF:
397	case ASN1_OP_END_SEQ_ACT:
398	case ASN1_OP_END_SET_OF_ACT:
399	case ASN1_OP_END_SEQ_OF_ACT:
400	if (unlikely(csp <= 0))
401	goto cons_stack_underflow;
402	csp--;
403	tdp = cons_dp_stack[csp];
404	hdr = cons_hdrlen_stack[csp];
405	len = datalen;
406	datalen = cons_datalen_stack[csp];
407	pr_debug("- end cons t=%zu dp=%zu l=%zu/%zu\n",
408	tdp, dp, len, datalen);
409	if (datalen == 0) {
410	/* Indefinite length - check for the EOC. */
411	datalen = len;
412	if (unlikely(datalen - dp < 2))
413	goto data_overrun_error;
414	if (data[dp++] != 0) {
415	if (op & ASN1_OP_END__OF) {
416	dp--;
417	csp++;
418	pc = machine[pc + 1];
419	pr_debug("- continue\n");
420	goto next_op;
421	}
422	goto missing_eoc;
423	}
424	if (data[dp++] != 0)
425	goto invalid_eoc;
426	len = dp - tdp - 2;
427	} else {
428	if (dp < len && (op & ASN1_OP_END__OF)) {
429	datalen = len;
430	csp++;
431	pc = machine[pc + 1];
432	pr_debug("- continue\n");
433	goto next_op;
434	}
435	if (dp != len)
436	goto cons_length_error;
437	len -= tdp;
438	pr_debug("- cons len l=%zu d=%zu\n", len, dp - tdp);
439	}
440
441	if (op & ASN1_OP_END__ACT) {
442	unsigned char act;
443	if (op & ASN1_OP_END__OF)
444	act = machine[pc + 2];
445	else
446	act = machine[pc + 1];
447	ret = actions[act](context, hdr, 0, data + tdp, len);
448	if (ret < 0)
449	return ret;
450	}
451	pc += asn1_op_lengths[op];
452	goto next_op;
453
454	case ASN1_OP_MAYBE_ACT:
455	if (!(flags & FLAG_LAST_MATCHED)) {
456	pc += asn1_op_lengths[op];
457	goto next_op;
458	}
459	/* fall through */
460
461	case ASN1_OP_ACT:
462	ret = actions[machine[pc + 1]](context, hdr, tag, data + tdp, len);
463	if (ret < 0)
464	return ret;
465	pc += asn1_op_lengths[op];
466	goto next_op;
467
468	case ASN1_OP_RETURN:
469	if (unlikely(jsp <= 0))
470	goto jump_stack_underflow;
471	pc = jump_stack[--jsp];
472	flags \|= FLAG_MATCHED \| FLAG_LAST_MATCHED;
473	goto next_op;
474
475	default:
476	break;
477	}
478
479	/* Shouldn't reach here */
480	pr_err("ASN.1 decoder error: Found reserved opcode (%u) pc=%zu\n",
481	op, pc);
482	return -EBADMSG;
483
484	data_overrun_error:
485	errmsg = "Data overrun error";
486	goto error;
487	machine_overrun_error:
488	errmsg = "Machine overrun error";
489	goto error;
490	jump_stack_underflow:
491	errmsg = "Jump stack underflow";
492	goto error;
493	jump_stack_overflow:
494	errmsg = "Jump stack overflow";
495	goto error;
496	cons_stack_underflow:
497	errmsg = "Cons stack underflow";
498	goto error;
499	cons_stack_overflow:
500	errmsg = "Cons stack overflow";
501	goto error;
502	cons_length_error:
503	errmsg = "Cons length error";
504	goto error;
505	missing_eoc:
506	errmsg = "Missing EOC in indefinite len cons";
507	goto error;
508	invalid_eoc:
509	errmsg = "Invalid length EOC";
510	goto error;
511	length_too_long:
512	errmsg = "Unsupported length";
513	goto error;
514	indefinite_len_primitive:
515	errmsg = "Indefinite len primitive not permitted";
516	goto error;
517	tag_mismatch:
518	errmsg = "Unexpected tag";
519	goto error;
520	long_tag_not_supported:
521	errmsg = "Long tag not supported";
522	error:
523	pr_debug("\nASN1: %s [m=%zu d=%zu ot=%02x t=%02x l=%zu]\n",
524	errmsg, pc, dp, optag, tag, len);
525	return -EBADMSG;
526	}
527	EXPORT_SYMBOL_GPL(asn1_ber_decoder);
528
529	MODULE_LICENSE("GPL");