[mirror_ubuntu-artful-kernel.git] / tools / net / bpf_jit_disasm.c

/*
 * Minimal BPF JIT image disassembler
 *
 * Disassembles BPF JIT compiler emitted opcodes back to asm insn's for
 * debugging or verification purposes.
 *
 * To get the disassembly of the JIT code, do the following:
 *
 *  1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
 *  2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
 *  3) Run e.g. `bpf_jit_disasm -o` to read out the last JIT code
 *
 * Copyright 2013 Daniel Borkmann <borkmann@redhat.com>
 * Licensed under the GNU General Public License, version 2.0 (GPLv2)
 */

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <unistd.h>
#include <string.h>
#include <bfd.h>
#include <dis-asm.h>
#include <regex.h>
#include <fcntl.h>
#include <sys/klog.h>
#include <sys/types.h>
#include <sys/stat.h>

#define CMD_ACTION_SIZE_BUFFER		10
#define CMD_ACTION_READ_ALL		3

static void get_exec_path(char *tpath, size_t size)
{
	char *path;
	ssize_t len;

	snprintf(tpath, size, "/proc/%d/exe", (int) getpid());
	tpath[size - 1] = 0;

	path = strdup(tpath);
	assert(path);

	len = readlink(path, tpath, size);
	tpath[len] = 0;

	free(path);
}

static void get_asm_insns(uint8_t *image, size_t len, int opcodes)
{
	int count, i, pc = 0;
	char tpath[256];
	struct disassemble_info info;
	disassembler_ftype disassemble;
	bfd *bfdf;

	memset(tpath, 0, sizeof(tpath));
	get_exec_path(tpath, sizeof(tpath));

	bfdf = bfd_openr(tpath, NULL);
	assert(bfdf);
	assert(bfd_check_format(bfdf, bfd_object));

	init_disassemble_info(&info, stdout, (fprintf_ftype) fprintf);
	info.arch = bfd_get_arch(bfdf);
	info.mach = bfd_get_mach(bfdf);
	info.buffer = image;
	info.buffer_length = len;

	disassemble_init_for_target(&info);

	disassemble = disassembler(bfdf);
	assert(disassemble);

	do {
		printf("%4x:\t", pc);

		count = disassemble(pc, &info);

		if (opcodes) {
			printf("\n\t");
			for (i = 0; i < count; ++i)
				printf("%02x ", (uint8_t) image[pc + i]);
		}
		printf("\n");

		pc += count;
	} while(count > 0 && pc < len);

	bfd_close(bfdf);
}

static char *get_klog_buff(unsigned int *klen)
{
	int ret, len;
	char *buff;

	len = klogctl(CMD_ACTION_SIZE_BUFFER, NULL, 0);
	if (len < 0)
		return NULL;

	buff = malloc(len);
	if (!buff)
		return NULL;

	ret = klogctl(CMD_ACTION_READ_ALL, buff, len);
	if (ret < 0) {
		free(buff);
		return NULL;
	}

	*klen = ret;
	return buff;
}

static char *get_flog_buff(const char *file, unsigned int *klen)
{
	int fd, ret, len;
	struct stat fi;
	char *buff;

	fd = open(file, O_RDONLY);
	if (fd < 0)
		return NULL;

	ret = fstat(fd, &fi);
	if (ret < 0 || !S_ISREG(fi.st_mode))
		goto out;

	len = fi.st_size + 1;
	buff = malloc(len);
	if (!buff)
		goto out;

	memset(buff, 0, len);
	ret = read(fd, buff, len - 1);
	if (ret <= 0)
		goto out_free;

	close(fd);
	*klen = ret;
	return buff;
out_free:
	free(buff);
out:
	close(fd);
	return NULL;
}

static char *get_log_buff(const char *file, unsigned int *klen)
{
	return file ? get_flog_buff(file, klen) : get_klog_buff(klen);
}

static void put_log_buff(char *buff)
{
	free(buff);
}

static unsigned int get_last_jit_image(char *haystack, size_t hlen,
				       uint8_t *image, size_t ilen)
{
	char *ptr, *pptr, *tmp;
	off_t off = 0;
	int ret, flen, proglen, pass, ulen = 0;
	regmatch_t pmatch[1];
	unsigned long base;
	regex_t regex;

	if (hlen == 0)
		return 0;

	ret = regcomp(&regex, "flen=[[:alnum:]]+ proglen=[[:digit:]]+ "
		      "pass=[[:digit:]]+ image=[[:xdigit:]]+", REG_EXTENDED);
	assert(ret == 0);

	ptr = haystack;
	memset(pmatch, 0, sizeof(pmatch));

	while (1) {
		ret = regexec(&regex, ptr, 1, pmatch, 0);
		if (ret == 0) {
			ptr += pmatch[0].rm_eo;
			off += pmatch[0].rm_eo;
			assert(off < hlen);
		} else
			break;
	}

	ptr = haystack + off - (pmatch[0].rm_eo - pmatch[0].rm_so);
	ret = sscanf(ptr, "flen=%d proglen=%d pass=%d image=%lx",
		     &flen, &proglen, &pass, &base);
	if (ret != 4) {
		regfree(&regex);
		return 0;
	}

	tmp = ptr = haystack + off;
	while ((ptr = strtok(tmp, "\n")) != NULL && ulen < ilen) {
		tmp = NULL;
		if (!strstr(ptr, "JIT code"))
			continue;
		pptr = ptr;
		while ((ptr = strstr(pptr, ":")))
			pptr = ptr + 1;
		ptr = pptr;
		do {
			image[ulen++] = (uint8_t) strtoul(pptr, &pptr, 16);
			if (ptr == pptr || ulen >= ilen) {
				ulen--;
				break;
			}
			ptr = pptr;
		} while (1);
	}

	assert(ulen == proglen);
	printf("%d bytes emitted from JIT compiler (pass:%d, flen:%d)\n",
	       proglen, pass, flen);
	printf("%lx + <x>:\n", base);

	regfree(&regex);
	return ulen;
}

static void usage(void)
{
	printf("Usage: bpf_jit_disasm [...]\n");
	printf("       -o          Also display related opcodes (default: off).\n");
	printf("       -O <file>   Write binary image of code to file, don't disassemble to stdout.\n");
	printf("       -f <file>   Read last image dump from file or stdin (default: klog).\n");
	printf("       -h          Display this help.\n");
}

int main(int argc, char **argv)
{
	unsigned int len, klen, opt, opcodes = 0;
	static uint8_t image[32768];
	char *kbuff, *file = NULL;
	char *ofile = NULL;
	int ofd;
	ssize_t nr;
	uint8_t *pos;

	while ((opt = getopt(argc, argv, "of:O:")) != -1) {
		switch (opt) {
		case 'o':
			opcodes = 1;
			break;
		case 'O':
			ofile = optarg;
			break;
		case 'f':
			file = optarg;
			break;
		default:
			usage();
			return -1;
		}
	}

	bfd_init();
	memset(image, 0, sizeof(image));

	kbuff = get_log_buff(file, &klen);
	if (!kbuff) {
		fprintf(stderr, "Could not retrieve log buffer!\n");
		return -1;
	}

	len = get_last_jit_image(kbuff, klen, image, sizeof(image));
	if (len <= 0) {
		fprintf(stderr, "No JIT image found!\n");
		goto done;
	}
	if (!ofile) {
		get_asm_insns(image, len, opcodes);
		goto done;
	}

	ofd = open(ofile, O_WRONLY | O_CREAT | O_TRUNC, DEFFILEMODE);
	if (ofd < 0) {
		fprintf(stderr, "Could not open file %s for writing: ", ofile);
		perror(NULL);
		goto done;
	}
	pos = image;
	do {
		nr = write(ofd, pos, len);
		if (nr < 0) {
			fprintf(stderr, "Could not write data to %s: ", ofile);
			perror(NULL);
			goto done;
		}
		len -= nr;
		pos += nr;
	} while (len);
	close(ofd);

done:
	put_log_buff(kbuff);
	return 0;
}
Commit	Line	Data
e306e2c1 DB	1	/*
	2	* Minimal BPF JIT image disassembler
	3	*
	4	* Disassembles BPF JIT compiler emitted opcodes back to asm insn's for
	5	* debugging or verification purposes.
	6	*
	7	* To get the disassembly of the JIT code, do the following:
	8	*
	9	* 1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
	10	* 2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
	11	* 3) Run e.g. `bpf_jit_disasm -o` to read out the last JIT code
	12	*
	13	* Copyright 2013 Daniel Borkmann <borkmann@redhat.com>
	14	* Licensed under the GNU General Public License, version 2.0 (GPLv2)
	15	*/
	16
	17	#include <stdint.h>
	18	#include <stdio.h>
	19	#include <stdlib.h>
	20	#include <assert.h>
	21	#include <unistd.h>
	22	#include <string.h>
	23	#include <bfd.h>
	24	#include <dis-asm.h>
a6ed3836 DB	25	#include <regex.h>
a6ed3836 DB	26	#include <fcntl.h>
e306e2c1 DB	27	#include <sys/klog.h>
e306e2c1 DB	28	#include <sys/types.h>
a6ed3836 DB	29	#include <sys/stat.h>
	30
	31	#define CMD_ACTION_SIZE_BUFFER 10
	32	#define CMD_ACTION_READ_ALL 3
e306e2c1 DB	33
	34	static void get_exec_path(char *tpath, size_t size)
	35	{
	36	char *path;
	37	ssize_t len;
	38
	39	snprintf(tpath, size, "/proc/%d/exe", (int) getpid());
	40	tpath[size - 1] = 0;
	41
	42	path = strdup(tpath);
	43	assert(path);
	44
	45	len = readlink(path, tpath, size);
	46	tpath[len] = 0;
	47
	48	free(path);
	49	}
	50
ed4afd45	51	static void get_asm_insns(uint8_t *image, size_t len, int opcodes)
e306e2c1 DB	52	{
	53	int count, i, pc = 0;
	54	char tpath[256];
	55	struct disassemble_info info;
	56	disassembler_ftype disassemble;
	57	bfd *bfdf;
	58
	59	memset(tpath, 0, sizeof(tpath));
	60	get_exec_path(tpath, sizeof(tpath));
	61
	62	bfdf = bfd_openr(tpath, NULL);
	63	assert(bfdf);
	64	assert(bfd_check_format(bfdf, bfd_object));
	65
	66	init_disassemble_info(&info, stdout, (fprintf_ftype) fprintf);
	67	info.arch = bfd_get_arch(bfdf);
	68	info.mach = bfd_get_mach(bfdf);
	69	info.buffer = image;
	70	info.buffer_length = len;
	71
	72	disassemble_init_for_target(&info);
	73
	74	disassemble = disassembler(bfdf);
	75	assert(disassemble);
	76
	77	do {
	78	printf("%4x:\t", pc);
	79
	80	count = disassemble(pc, &info);
	81
	82	if (opcodes) {
	83	printf("\n\t");
	84	for (i = 0; i < count; ++i)
	85	printf("%02x ", (uint8_t) image[pc + i]);
	86	}
	87	printf("\n");
	88
	89	pc += count;
	90	} while(count > 0 && pc < len);
	91
	92	bfd_close(bfdf);
	93	}
	94
a6ed3836	95	static char get_klog_buff(unsigned int klen)
e306e2c1	96	{
a6ed3836 DB	97	int ret, len;
	98	char *buff;
	99
	100	len = klogctl(CMD_ACTION_SIZE_BUFFER, NULL, 0);
25a54342 CIK	101	if (len < 0)
	102	return NULL;
	103
a6ed3836 DB	104	buff = malloc(len);
	105	if (!buff)
	106	return NULL;
	107
	108	ret = klogctl(CMD_ACTION_READ_ALL, buff, len);
	109	if (ret < 0) {
	110	free(buff);
	111	return NULL;
	112	}
e306e2c1	113
e306e2c1	114	*klen = ret;
a6ed3836 DB	115	return buff;
a6ed3836 DB	116	}
e306e2c1	117
a6ed3836 DB	118	static char get_flog_buff(const char file, unsigned int *klen)
	119	{
	120	int fd, ret, len;
	121	struct stat fi;
	122	char *buff;
	123
	124	fd = open(file, O_RDONLY);
	125	if (fd < 0)
	126	return NULL;
	127
	128	ret = fstat(fd, &fi);
	129	if (ret < 0 \|\| !S_ISREG(fi.st_mode))
	130	goto out;
	131
	132	len = fi.st_size + 1;
	133	buff = malloc(len);
	134	if (!buff)
	135	goto out;
	136
	137	memset(buff, 0, len);
	138	ret = read(fd, buff, len - 1);
	139	if (ret <= 0)
	140	goto out_free;
	141
	142	close(fd);
	143	*klen = ret;
e306e2c1	144	return buff;
a6ed3836 DB	145	out_free:
	146	free(buff);
	147	out:
	148	close(fd);
	149	return NULL;
	150	}
	151
	152	static char get_log_buff(const char file, unsigned int *klen)
	153	{
	154	return file ? get_flog_buff(file, klen) : get_klog_buff(klen);
e306e2c1 DB	155	}
e306e2c1 DB	156
a6ed3836	157	static void put_log_buff(char *buff)
e306e2c1 DB	158	{
	159	free(buff);
	160	}
	161
4de61ba2 AH	162	static unsigned int get_last_jit_image(char *haystack, size_t hlen,
4de61ba2 AH	163	uint8_t *image, size_t ilen)
e306e2c1 DB	164	{
	165	char ptr, pptr, *tmp;
	166	off_t off = 0;
	167	int ret, flen, proglen, pass, ulen = 0;
	168	regmatch_t pmatch[1];
ed4afd45	169	unsigned long base;
e306e2c1 DB	170	regex_t regex;
	171
	172	if (hlen == 0)
	173	return 0;
	174
	175	ret = regcomp(&regex, "flen=[[:alnum:]]+ proglen=[[:digit:]]+ "
	176	"pass=[[:digit:]]+ image=[[:xdigit:]]+", REG_EXTENDED);
	177	assert(ret == 0);
	178
	179	ptr = haystack;
082739aa DB	180	memset(pmatch, 0, sizeof(pmatch));
082739aa DB	181
e306e2c1 DB	182	while (1) {
	183	ret = regexec(&regex, ptr, 1, pmatch, 0);
	184	if (ret == 0) {
	185	ptr += pmatch[0].rm_eo;
	186	off += pmatch[0].rm_eo;
	187	assert(off < hlen);
	188	} else
	189	break;
	190	}
	191
	192	ptr = haystack + off - (pmatch[0].rm_eo - pmatch[0].rm_so);
	193	ret = sscanf(ptr, "flen=%d proglen=%d pass=%d image=%lx",
ed4afd45	194	&flen, &proglen, &pass, &base);
a6ed3836 DB	195	if (ret != 4) {
a6ed3836 DB	196	regfree(&regex);
e306e2c1	197	return 0;
a6ed3836	198	}
e306e2c1 DB	199
	200	tmp = ptr = haystack + off;
	201	while ((ptr = strtok(tmp, "\n")) != NULL && ulen < ilen) {
	202	tmp = NULL;
	203	if (!strstr(ptr, "JIT code"))
	204	continue;
	205	pptr = ptr;
	206	while ((ptr = strstr(pptr, ":")))
	207	pptr = ptr + 1;
	208	ptr = pptr;
	209	do {
	210	image[ulen++] = (uint8_t) strtoul(pptr, &pptr, 16);
	211	if (ptr == pptr \|\| ulen >= ilen) {
	212	ulen--;
	213	break;
	214	}
	215	ptr = pptr;
	216	} while (1);
	217	}
	218
	219	assert(ulen == proglen);
	220	printf("%d bytes emitted from JIT compiler (pass:%d, flen:%d)\n",
	221	proglen, pass, flen);
ed4afd45	222	printf("%lx + <x>:\n", base);
e306e2c1 DB	223
	224	regfree(&regex);
	225	return ulen;
	226	}
	227
a6ed3836 DB	228	static void usage(void)
	229	{
	230	printf("Usage: bpf_jit_disasm [...]\n");
	231	printf(" -o Also display related opcodes (default: off).\n");
b6518e6a	232	printf(" -O <file> Write binary image of code to file, don't disassemble to stdout.\n");
a6ed3836 DB	233	printf(" -f <file> Read last image dump from file or stdin (default: klog).\n");
	234	printf(" -h Display this help.\n");
	235	}
	236
e306e2c1 DB	237	int main(int argc, char **argv)
e306e2c1 DB	238	{
a6ed3836	239	unsigned int len, klen, opt, opcodes = 0;
9bb1a208	240	static uint8_t image[32768];
a6ed3836	241	char kbuff, file = NULL;
b6518e6a DD	242	char *ofile = NULL;
	243	int ofd;
	244	ssize_t nr;
	245	uint8_t *pos;
e306e2c1	246
b6518e6a	247	while ((opt = getopt(argc, argv, "of:O:")) != -1) {
a6ed3836 DB	248	switch (opt) {
a6ed3836 DB	249	case 'o':
e306e2c1	250	opcodes = 1;
a6ed3836	251	break;
b6518e6a DD	252	case 'O':
	253	ofile = optarg;
	254	break;
a6ed3836 DB	255	case 'f':
	256	file = optarg;
	257	break;
	258	default:
	259	usage();
	260	return -1;
e306e2c1 DB	261	}
	262	}
	263
	264	bfd_init();
	265	memset(image, 0, sizeof(image));
	266
a6ed3836 DB	267	kbuff = get_log_buff(file, &klen);
	268	if (!kbuff) {
	269	fprintf(stderr, "Could not retrieve log buffer!\n");
	270	return -1;
	271	}
e306e2c1	272
ed4afd45	273	len = get_last_jit_image(kbuff, klen, image, sizeof(image));
b6518e6a	274	if (len <= 0) {
a6ed3836	275	fprintf(stderr, "No JIT image found!\n");
b6518e6a DD	276	goto done;
	277	}
	278	if (!ofile) {
	279	get_asm_insns(image, len, opcodes);
	280	goto done;
	281	}
	282
	283	ofd = open(ofile, O_WRONLY \| O_CREAT \| O_TRUNC, DEFFILEMODE);
	284	if (ofd < 0) {
	285	fprintf(stderr, "Could not open file %s for writing: ", ofile);
	286	perror(NULL);
	287	goto done;
	288	}
	289	pos = image;
	290	do {
	291	nr = write(ofd, pos, len);
	292	if (nr < 0) {
	293	fprintf(stderr, "Could not write data to %s: ", ofile);
	294	perror(NULL);
	295	goto done;
	296	}
	297	len -= nr;
	298	pos += nr;
	299	} while (len);
	300	close(ofd);
e306e2c1	301
b6518e6a	302	done:
a6ed3836	303	put_log_buff(kbuff);
e306e2c1 DB	304	return 0;
e306e2c1 DB	305	}