Commit a581ed81 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'net-af_packet-allow-joining-a-fanout-when-link-is-down' 

Gur Stavi says:

====================
net: af_packet: allow joining a fanout when link is down

PACKET socket can retain its fanout membership through link down and up
and leave a fanout while closed regardless of link state.
However, socket was forbidden from joining a fanout while it was not
RUNNING.

This scenario was identified while studying DPDK pmd_af_packet_drv.
Since sockets are only created during initialization, there is no reason
to fail the initialization if a single link is temporarily down.

This patch allows PACKET socket to join a fanout while not RUNNING.

Selftest psock_fanout is extended to test this "fanout while link down"
scenario.

Selftest psock_fanout is also extended to test fanout create/join by
socket that did not bind or specified a protocol, which carries an
implicit bind.

v3: https://lore.kernel.org/cover.1728555449.git.gur.stavi@huawei.com
v2: https://lore.kernel.org/cover.1728382839.git.gur.stavi@huawei.com
v1: https://lore.kernel.org/cover.1728303615.git.gur.stavi@huawei.com
====================

Link: https://patch.msgid.link/cover.1728802323.git.gur.stavi@huawei.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents e3fc5139 7ec02a3a

net/packet/af_packet.c

+5 −4
Original line number Diff line number Diff line
@@ -1846,21 +1846,22 @@ static int fanout_add(struct sock *sk, struct fanout_args *args) 
	err = -EINVAL;



	spin_lock(&po->bind_lock);

	if (packet_sock_flag(po, PACKET_SOCK_RUNNING) &&

	if (po->num &&

	    match->type == type &&

	    match->prot_hook.type == po->prot_hook.type &&

	    match->prot_hook.dev == po->prot_hook.dev) {

		err = -ENOSPC;

		if (refcount_read(&match->sk_ref) < match->max_num_members) {

			__dev_remove_pack(&po->prot_hook);



			/* Paired with packet_setsockopt(PACKET_FANOUT_DATA) */

			WRITE_ONCE(po->fanout, match);



			po->rollover = rollover;

			rollover = NULL;

			refcount_set(&match->sk_ref, refcount_read(&match->sk_ref) + 1);

			if (packet_sock_flag(po, PACKET_SOCK_RUNNING)) {

				__dev_remove_pack(&po->prot_hook);

				__fanout_link(sk, po);

			}

			err = 0;

		}

	}

tools/testing/selftests/net/psock_fanout.c

+75 −3
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ 
#include <string.h>

#include <sys/mman.h>

#include <sys/socket.h>

#include <sys/ioctl.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <unistd.h>
@@ -59,6 +60,33 @@ 


static uint32_t cfg_max_num_members;



static void loopback_set_up_down(int state_up)

{

	struct ifreq ifreq = {};

	int fd, err;



	fd = socket(AF_PACKET, SOCK_RAW, 0);

	if (fd < 0) {

		perror("socket loopback");

		exit(1);

	}

	strcpy(ifreq.ifr_name, "lo");

	err = ioctl(fd, SIOCGIFFLAGS, &ifreq);

	if (err) {

		perror("SIOCGIFFLAGS");

		exit(1);

	}

	if (state_up != !!(ifreq.ifr_flags & IFF_UP)) {

		ifreq.ifr_flags ^= IFF_UP;

		err = ioctl(fd, SIOCSIFFLAGS, &ifreq);

		if (err) {

			perror("SIOCSIFFLAGS");

			exit(1);

		}

	}

	close(fd);

}



/* Open a socket in a given fanout mode.

 * @return -1 if mode is bad, a valid socket otherwise */

static int sock_fanout_open(uint16_t typeflags, uint16_t group_id)
@@ -251,6 +279,41 @@ static int sock_fanout_read(int fds[], char *rings[], const int expect[]) 
	return 0;

}



/* Test that creating/joining a fanout group fails for unbound socket without

 * a specified protocol

 */

static void test_unbound_fanout(void)

{

	int val, fd0, fd1, err;



	fprintf(stderr, "test: unbound fanout\n");

	fd0 = socket(PF_PACKET, SOCK_RAW, 0);

	if (fd0 < 0) {

		perror("socket packet");

		exit(1);

	}

	/* Try to create a new fanout group. Should fail. */

	val = (PACKET_FANOUT_HASH << 16) | 1;

	err = setsockopt(fd0, SOL_PACKET, PACKET_FANOUT, &val, sizeof(val));

	if (!err) {

		fprintf(stderr, "ERROR: unbound socket fanout create\n");

		exit(1);

	}

	fd1 = sock_fanout_open(PACKET_FANOUT_HASH, 1);

	if (fd1 == -1) {

		fprintf(stderr, "ERROR: failed to open HASH socket\n");

		exit(1);

	}

	/* Try to join an existing fanout group. Should fail. */

	err = setsockopt(fd0, SOL_PACKET, PACKET_FANOUT, &val, sizeof(val));

	if (!err) {

		fprintf(stderr, "ERROR: unbound socket fanout join\n");

		exit(1);

	}

	close(fd0);

	close(fd1);

}



/* Test illegal mode + flag combination */

static void test_control_single(void)

{
@@ -264,10 +327,13 @@ static void test_control_single(void) 
}



/* Test illegal group with different modes or flags */

static void test_control_group(void)

static void test_control_group(int toggle)

{

	int fds[2];



	if (toggle)

		fprintf(stderr, "test: control multiple sockets with link down toggle\n");

	else

		fprintf(stderr, "test: control multiple sockets\n");



	fds[0] = sock_fanout_open(PACKET_FANOUT_HASH, 0);
@@ -275,6 +341,8 @@ static void test_control_group(void) 
		fprintf(stderr, "ERROR: failed to open HASH socket\n");

		exit(1);

	}

	if (toggle)

		loopback_set_up_down(0);

	if (sock_fanout_open(PACKET_FANOUT_HASH |

			       PACKET_FANOUT_FLAG_DEFRAG, 0) != -1) {

		fprintf(stderr, "ERROR: joined group with wrong flag defrag\n");
@@ -294,6 +362,8 @@ static void test_control_group(void) 
		fprintf(stderr, "ERROR: failed to join group\n");

		exit(1);

	}

	if (toggle)

		loopback_set_up_down(1);

	if (close(fds[1]) || close(fds[0])) {

		fprintf(stderr, "ERROR: closing sockets\n");

		exit(1);
@@ -488,8 +558,10 @@ int main(int argc, char **argv) 
	const int expect_uniqueid[2][2] = { { 20, 20},  { 20, 20 } };

	int port_off = 2, tries = 20, ret;



	test_unbound_fanout();

	test_control_single();

	test_control_group();

	test_control_group(0);

	test_control_group(1);

	test_control_group_max_num_members();

	test_unique_fanout_group_ids();