Re: [PATCH nf-next 2/2] netfilter: nfnetlink_log: validate dependencies to avoid breaking atomicity

[Ken-ichirou MATSUZAWA <chamaken@gmail.com>]

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 Thank you for your usual support.
 
On Tue, Oct 13, 2015 at 12:47:47PM +0200, Pablo Neira Ayuso wrote:
> @Ken-ichirou: Could you give a test to this patches? Thanks.

I've tested these with appended and is fine, of course.
Before applying patches:

    # ./a.out 123
    a.out: empty_cfg.c:56: main: Assertion `mnl_cb_run(buf, ret, 0, portid, ((void *)0), ((void *)0)) == -1' failed.
    Aborted

On Tue, Oct 13, 2015 at 12:47:48PM +0200, Pablo Neira Ayuso wrote:
> +#ifdef CONFIG_MODULES
> +			nfnl_unlock(NFNL_SUBSYS_ULOG);
> +			request_module("ip_conntrack_netlink");
> +			nfnl_lock(NFNL_SUBSYS_ULOG);
> +			if (rcu_access_pointer(nfnl_ct_hook)) {
> +				ret = -EAGAIN;
> +				goto out_put;
> +			}
> +#endif
> +			ret = -EOPNOTSUPP;
> +			goto out_put;

It's off the subject, but this fixes module unload. It was not
put instance at my first patch, Thanks!

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/*
 * This example is placed in the public domain.
 * cc empty_cfg.c -lmnl -lnetfilter_log
 */

#include <stdio.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <errno.h>
#include <assert.h>

#include <linux/netfilter/nfnetlink_log.h>

#include <libmnl/libmnl.h>
#include <libnetfilter_log/libnetfilter_log.h>

int main(int argc, char *argv[])
{
	struct mnl_socket *nl;
	char buf[MNL_SOCKET_BUFFER_SIZE];
	struct nlmsghdr *nlh;
	int ret;
	unsigned int portid, qnum;

	if (argc != 2) {
		printf("Usage: %s [queue_num]\n", argv[0]);
		exit(EXIT_FAILURE);
	}
	qnum = atoi(argv[1]);

	nl = mnl_socket_open(NETLINK_NETFILTER);
	if (nl == NULL) {
		perror("mnl_socket_open");
		exit(EXIT_FAILURE);
	}

	if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
		perror("mnl_socket_bind");
		exit(EXIT_FAILURE);
	}
	portid = mnl_socket_get_portid(nl);

	nlh = nflog_nlmsg_put_header(buf, NFULNL_MSG_CONFIG, AF_UNSPEC, qnum);
	nlh->nlmsg_flags |= NLM_F_ACK;
	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
		perror("mnl_socket_sendto");
		exit(EXIT_FAILURE);
	}

	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
	if (ret == -1) {
		perror("mnl_socket_recvfrom");
		exit(EXIT_FAILURE);
	}

	assert(mnl_cb_run(buf, ret, 0, portid, NULL, NULL) == MNL_CB_ERROR);
	assert(errno == ENODEV);

	mnl_socket_close(nl);

	return 0;
}