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Commit a664a834 authored by Peter Wu's avatar Peter Wu Committed by Daniel Borkmann
Browse files

tools: bpftool: fix reading from /proc/config.gz 



/proc/config has never existed as far as I can see, but /proc/config.gz
is present on Arch Linux. Add support for decompressing config.gz using
zlib which is a mandatory dependency of libelf anyway. Replace existing
stdio functions with gzFile operations since the latter transparently
handles uncompressed and gzip-compressed files.

Cc: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: default avatarPeter Wu <peter@lekensteyn.nl>
Reviewed-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 9f30cd56

tools/bpf/bpftool/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -52,7 +52,7 @@ ifneq ($(EXTRA_LDFLAGS),) 
LDFLAGS += $(EXTRA_LDFLAGS)

endif



LIBS = -lelf $(LIBBPF)

LIBS = -lelf -lz $(LIBBPF)



INSTALL ?= install

RM ?= rm -f

tools/bpf/bpftool/feature.c

+53 −52
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 


#include <bpf.h>

#include <libbpf.h>

#include <zlib.h>



#include "main.h"
@@ -284,34 +285,32 @@ static void probe_jit_limit(void) 
	}

}



static char *get_kernel_config_option(FILE *fd, const char *option)

static bool read_next_kernel_config_option(gzFile file, char *buf, size_t n,

					   char **value)

{

	size_t line_n = 0, optlen = strlen(option);

	char *res, *strval, *line = NULL;

	ssize_t n;

	char *sep;



	rewind(fd);

	while ((n = getline(&line, &line_n, fd)) > 0) {

		if (strncmp(line, option, optlen))

	while (gzgets(file, buf, n)) {

		if (strncmp(buf, "CONFIG_", 7))

			continue;

		/* Check we have at least '=', value, and '\n' */

		if (strlen(line) < optlen + 3)

			continue;

		if (*(line + optlen) != '=')



		sep = strchr(buf, '=');

		if (!sep)

			continue;



		/* Trim ending '\n' */

		line[strlen(line) - 1] = '\0';

		buf[strlen(buf) - 1] = '\0';



		/* Copy and return config option value */

		strval = line + optlen + 1;

		res = strdup(strval);

		free(line);

		return res;

		/* Split on '=' and ensure that a value is present. */

		*sep = '\0';

		if (!sep[1])

			continue;



		*value = sep + 1;

		return true;

	}

	free(line);



	return NULL;

	return false;

}



static void probe_kernel_image_config(void)
@@ -386,59 +385,61 @@ static void probe_kernel_image_config(void) 
		/* test_bpf module for BPF tests */

		"CONFIG_TEST_BPF",

	};

	char *value, *buf = NULL;

	char *values[ARRAY_SIZE(options)] = { };

	struct utsname utsn;

	char path[PATH_MAX];

	size_t i, n;

	ssize_t ret;

	FILE *fd;



	if (uname(&utsn))

		goto no_config;

	gzFile file = NULL;

	char buf[4096];

	char *value;

	size_t i;



	if (!uname(&utsn)) {

		snprintf(path, sizeof(path), "/boot/config-%s", utsn.release);



	fd = fopen(path, "r");

	if (!fd && errno == ENOENT) {

		/* Some distributions put the config file at /proc/config, give

		 * it a try.

		 * Sometimes it is also at /proc/config.gz but we do not try

		 * this one for now, it would require linking against libz.

		/* gzopen also accepts uncompressed files. */

		file = gzopen(path, "r");

	}



	if (!file) {

		/* Some distributions build with CONFIG_IKCONFIG=y and put the

		 * config file at /proc/config.gz.

		 */

		fd = fopen("/proc/config", "r");

		file = gzopen("/proc/config.gz", "r");

	}

	if (!fd) {

	if (!file) {

		p_info("skipping kernel config, can't open file: %s",

		       strerror(errno));

		goto no_config;

		goto end_parse;

	}

	/* Sanity checks */

	ret = getline(&buf, &n, fd);

	ret = getline(&buf, &n, fd);

	if (!buf || !ret) {

	if (!gzgets(file, buf, sizeof(buf)) ||

	    !gzgets(file, buf, sizeof(buf))) {

		p_info("skipping kernel config, can't read from file: %s",

		       strerror(errno));

		free(buf);

		goto no_config;

		goto end_parse;

	}

	if (strcmp(buf, "# Automatically generated file; DO NOT EDIT.\n")) {

		p_info("skipping kernel config, can't find correct file");

		free(buf);

		goto no_config;

		goto end_parse;

	}

	free(buf);



	while (read_next_kernel_config_option(file, buf, sizeof(buf), &value)) {

		for (i = 0; i < ARRAY_SIZE(options); i++) {

		value = get_kernel_config_option(fd, options[i]);

		print_kernel_option(options[i], value);

		free(value);

			if (values[i] || strcmp(buf, options[i]))

				continue;



			values[i] = strdup(value);

		}

	fclose(fd);

	return;

	}



end_parse:

	if (file)

		gzclose(file);



no_config:

	for (i = 0; i < ARRAY_SIZE(options); i++)

		print_kernel_option(options[i], NULL);

	for (i = 0; i < ARRAY_SIZE(options); i++) {

		print_kernel_option(options[i], values[i]);

		free(values[i]);

	}

}



static bool probe_bpf_syscall(const char *define_prefix)