linux/tools/bpf/bpftool/xlated_dumper.c

// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
/*
 * Copyright (C) 2018 Netronome Systems, Inc.
 *
 * This software is dual licensed under the GNU General License Version 2,
 * June 1991 as shown in the file COPYING in the top-level directory of this
 * source tree or the BSD 2-Clause License provided below.  You have the
 * option to license this software under the complete terms of either license.
 *
 * The BSD 2-Clause License:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      1. Redistributions of source code must retain the above
 *         copyright notice, this list of conditions and the following
 *         disclaimer.
 *
 *      2. Redistributions in binary form must reproduce the above
 *         copyright notice, this list of conditions and the following
 *         disclaimer in the documentation and/or other materials
 *         provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>

#include "disasm.h"
#include "json_writer.h"
#include "main.h"
#include "xlated_dumper.h"

static int kernel_syms_cmp(const void *sym_a, const void *sym_b)
{
	return ((struct kernel_sym *)sym_a)->address -
	       ((struct kernel_sym *)sym_b)->address;
}

void kernel_syms_load(struct dump_data *dd)
{
	struct kernel_sym *sym;
	char buff[256];
	void *tmp, *address;
	FILE *fp;

	fp = fopen("/proc/kallsyms", "r");
	if (!fp)
		return;

	while (!feof(fp)) {
		if (!fgets(buff, sizeof(buff), fp))
			break;
		tmp = realloc(dd->sym_mapping,
			      (dd->sym_count + 1) *
			      sizeof(*dd->sym_mapping));
		if (!tmp) {
out:
			free(dd->sym_mapping);
			dd->sym_mapping = NULL;
			fclose(fp);
			return;
		}
		dd->sym_mapping = tmp;
		sym = &dd->sym_mapping[dd->sym_count];
		if (sscanf(buff, "%p %*c %s", &address, sym->name) != 2)
			continue;
		sym->address = (unsigned long)address;
		if (!strcmp(sym->name, "__bpf_call_base")) {
			dd->address_call_base = sym->address;
			/* sysctl kernel.kptr_restrict was set */
			if (!sym->address)
				goto out;
		}
		if (sym->address)
			dd->sym_count++;
	}

	fclose(fp);

	qsort(dd->sym_mapping, dd->sym_count,
	      sizeof(*dd->sym_mapping), kernel_syms_cmp);
}

void kernel_syms_destroy(struct dump_data *dd)
{
	free(dd->sym_mapping);
}

static struct kernel_sym *kernel_syms_search(struct dump_data *dd,
					     unsigned long key)
{
	struct kernel_sym sym = {
		.address = key,
	};

	return dd->sym_mapping ?
	       bsearch(&sym, dd->sym_mapping, dd->sym_count,
		       sizeof(*dd->sym_mapping), kernel_syms_cmp) : NULL;
}

static void print_insn(struct bpf_verifier_env *env, const char *fmt, ...)
{
	va_list args;

	va_start(args, fmt);
	vprintf(fmt, args);
	va_end(args);
}

static void print_insn_json(struct bpf_verifier_env *env, const char *fmt, ...)
{
	unsigned int l = strlen(fmt);
	char chomped_fmt[l];
	va_list args;

	va_start(args, fmt);
	if (l > 0) {
		strncpy(chomped_fmt, fmt, l - 1);
		chomped_fmt[l - 1] = '\0';
	}
	jsonw_vprintf_enquote(json_wtr, chomped_fmt, args);
	va_end(args);
}

static const char *print_call_pcrel(struct dump_data *dd,
				    struct kernel_sym *sym,
				    unsigned long address,
				    const struct bpf_insn *insn)
{
	if (sym)
		snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
			 "%+d#%s", insn->off, sym->name);
	else
		snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
			 "%+d#0x%lx", insn->off, address);
	return dd->scratch_buff;
}

static const char *print_call_helper(struct dump_data *dd,
				     struct kernel_sym *sym,
				     unsigned long address)
{
	if (sym)
		snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
			 "%s", sym->name);
	else
		snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
			 "0x%lx", address);
	return dd->scratch_buff;
}

static const char *print_call(void *private_data,
			      const struct bpf_insn *insn)
{
	struct dump_data *dd = private_data;
	unsigned long address = dd->address_call_base + insn->imm;
	struct kernel_sym *sym;

	sym = kernel_syms_search(dd, address);
	if (insn->src_reg == BPF_PSEUDO_CALL)
		return print_call_pcrel(dd, sym, address, insn);
	else
		return print_call_helper(dd, sym, address);
}

static const char *print_imm(void *private_data,
			     const struct bpf_insn *insn,
			     __u64 full_imm)
{
	struct dump_data *dd = private_data;

	if (insn->src_reg == BPF_PSEUDO_MAP_FD)
		snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
			 "map[id:%u]", insn->imm);
	else
		snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
			 "0x%llx", (unsigned long long)full_imm);
	return dd->scratch_buff;
}

void dump_xlated_json(struct dump_data *dd, void *buf, unsigned int len,
		      bool opcodes)
{
	const struct bpf_insn_cbs cbs = {
		.cb_print	= print_insn_json,
		.cb_call	= print_call,
		.cb_imm		= print_imm,
		.private_data	= dd,
	};
	struct bpf_insn *insn = buf;
	bool double_insn = false;
	unsigned int i;

	jsonw_start_array(json_wtr);
	for (i = 0; i < len / sizeof(*insn); i++) {
		if (double_insn) {
			double_insn = false;
			continue;
		}
		double_insn = insn[i].code == (BPF_LD | BPF_IMM | BPF_DW);

		jsonw_start_object(json_wtr);
		jsonw_name(json_wtr, "disasm");
		print_bpf_insn(&cbs, NULL, insn + i, true);

		if (opcodes) {
			jsonw_name(json_wtr, "opcodes");
			jsonw_start_object(json_wtr);

			jsonw_name(json_wtr, "code");
			jsonw_printf(json_wtr, "\"0x%02hhx\"", insn[i].code);

			jsonw_name(json_wtr, "src_reg");
			jsonw_printf(json_wtr, "\"0x%hhx\"", insn[i].src_reg);

			jsonw_name(json_wtr, "dst_reg");
			jsonw_printf(json_wtr, "\"0x%hhx\"", insn[i].dst_reg);

			jsonw_name(json_wtr, "off");
			print_hex_data_json((uint8_t *)(&insn[i].off), 2);

			jsonw_name(json_wtr, "imm");
			if (double_insn && i < len - 1)
				print_hex_data_json((uint8_t *)(&insn[i].imm),
						    12);
			else
				print_hex_data_json((uint8_t *)(&insn[i].imm),
						    4);
			jsonw_end_object(json_wtr);
		}
		jsonw_end_object(json_wtr);
	}
	jsonw_end_array(json_wtr);
}

void dump_xlated_plain(struct dump_data *dd, void *buf, unsigned int len,
		       bool opcodes)
{
	const struct bpf_insn_cbs cbs = {
		.cb_print	= print_insn,
		.cb_call	= print_call,
		.cb_imm		= print_imm,
		.private_data	= dd,
	};
	struct bpf_insn *insn = buf;
	bool double_insn = false;
	unsigned int i;

	for (i = 0; i < len / sizeof(*insn); i++) {
		if (double_insn) {
			double_insn = false;
			continue;
		}

		double_insn = insn[i].code == (BPF_LD | BPF_IMM | BPF_DW);

		printf("% 4d: ", i);
		print_bpf_insn(&cbs, NULL, insn + i, true);

		if (opcodes) {
			printf("       ");
			fprint_hex(stdout, insn + i, 8, " ");
			if (double_insn && i < len - 1) {
				printf(" ");
				fprint_hex(stdout, insn + i + 1, 8, " ");
			}
			printf("\n");
		}
	}
}