[U-Boot] [PATCH v1 06/11] lib: add asn1 decoder

Heinrich Schuchardt
2019-10-12T12:29:49Z

On 10/11/19 9:41 AM, AKASHI Takahiro wrote:
> Imported from linux kernel v5.3.
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> ---
> lib/Kconfig | 6 +
> lib/Makefile | 1 +
> lib/asn1_decoder.c | 527 +++++++++++++++++++++++++++++++++++++++++++++

Except for adjustments of include files lib/asn1_decoder.c is a
verbatime copy of the Linux kernel file. OK.

> 3 files changed, 534 insertions(+)
> create mode 100644 lib/asn1_decoder.c
>
> diff --git a/lib/Kconfig b/lib/Kconfig
> index 3da45a5ec322..26c94f49ecd2 100644
> --- a/lib/Kconfig
> +++ b/lib/Kconfig
> @@ -521,6 +521,12 @@ config SMBIOS_PRODUCT_NAME
>
> endmenu
>
> +config ASN1
> + bool
> + select BUILD_ASN1

BUILD_ASN1 does not really fit into cmd/Kconfig.

Should we move it here?

Why do we need two separate flags ASN1 and BUILD_ASN1?

Best regards

Heinrich

> + help
> + Enable asn1 decoder library.
> +
> source lib/efi/Kconfig
> source lib/efi_loader/Kconfig
> source lib/optee/Kconfig
> diff --git a/lib/Makefile b/lib/Makefile
> index 2fffd68f943c..eb3a675fb8c2 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -17,6 +17,7 @@ obj-$(CONFIG_OF_LIVE) += of_live.o
> obj-$(CONFIG_CMD_DHRYSTONE) += dhry/
> obj-$(CONFIG_ARCH_AT91) += at91/
> obj-$(CONFIG_OPTEE) += optee/
> +obj-$(CONFIG_BUILD_ASN1) += asn1_decoder.o
>
> obj-$(CONFIG_AES) += aes.o
>
> diff --git a/lib/asn1_decoder.c b/lib/asn1_decoder.c
> new file mode 100644
> index 000000000000..db222625dd0f
> --- /dev/null
> +++ b/lib/asn1_decoder.c
> @@ -0,0 +1,527 @@
> +// 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 at redhat.com)
> + */
> +
> +#ifdef __UBOOT__
> +#include <linux/compat.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");
>