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[RFC PATCH 3/3] bpf: Add sk_lookup test to use ORIGDSTADDR cmsg.

Tiago Lam posted 3 patches 2 months, 2 weeks ago
[RFC PATCH 3/3] bpf: Add sk_lookup test to use ORIGDSTADDR cmsg.
Posted by Tiago Lam 2 months, 2 weeks ago 
This patch reuses the framework already in place for sk_lookup, allowing
it now to send a reply from the server fd directly, instead of having to
create a socket bound to the original destination address and reply from
there. It does this by passing the source address and port from where to
reply from in a IP_ORIGDSTADDR ancilliary message passed in sendmsg.

Signed-off-by: Tiago Lam <tiagolam@cloudflare.com>
---
 tools/testing/selftests/bpf/prog_tests/sk_lookup.c | 70 +++++++++++++++-------
 1 file changed, 48 insertions(+), 22 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
index ae87c00867ba..b99aff2e3976 100644
--- a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
+++ b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
@@ -75,6 +75,7 @@ struct test {
 	struct inet_addr listen_at;
 	enum server accept_on;
 	bool reuseport_has_conns; /* Add a connected socket to reuseport group */
+	bool dont_bind_reply; /* Don't bind, send direct from server fd. */
 };
 
 struct cb_opts {
@@ -363,7 +364,7 @@ static void v4_to_v6(struct sockaddr_storage *ss)
 	memset(&v6->sin6_addr.s6_addr[0], 0, 10);
 }
 
-static int udp_recv_send(int server_fd)
+static int udp_recv_send(int server_fd, bool dont_bind_reply)
 {
 	char cmsg_buf[CMSG_SPACE(sizeof(struct sockaddr_storage))];
 	struct sockaddr_storage _src_addr = { 0 };
@@ -415,26 +416,41 @@ static int udp_recv_send(int server_fd)
 		v4_to_v6(dst_addr);
 	}
 
-	/* Reply from original destination address. */
-	fd = start_server_addr(SOCK_DGRAM, dst_addr, sizeof(*dst_addr), NULL);
-	if (!ASSERT_OK_FD(fd, "start_server_addr")) {
-		log_err("failed to create tx socket");
-		return -1;
-	}
+	if (dont_bind_reply) {
+		/* Reply directly from server fd, specifying the source address and/or
+		 * port in struct msghdr.
+		 */
+		n = sendmsg(server_fd, &msg, 0);
+		if (CHECK(n <= 0, "sendmsg", "failed\n")) {
+			log_err("failed to send echo reply");
+			return -1;
+		}
+	} else {
+		/* Reply from original destination address. */
+		fd = socket(dst_addr->ss_family, SOCK_DGRAM, 0);
+		if (CHECK(fd < 0, "socket", "failed\n")) {
+			log_err("failed to create tx socket");
+			return -1;
+		}
 
-	msg.msg_control = NULL;
-	msg.msg_controllen = 0;
-	n = sendmsg(fd, &msg, 0);
-	if (CHECK(n <= 0, "sendmsg", "failed\n")) {
-		log_err("failed to send echo reply");
-		ret = -1;
-		goto out;
-	}
+		ret = bind(fd, (struct sockaddr *)dst_addr, sizeof(*dst_addr));
+		if (CHECK(ret, "bind", "failed\n")) {
+			log_err("failed to bind tx socket");
+			close(fd);
+			return ret;
+		}
 
-	ret = 0;
-out:
-	close(fd);
-	return ret;
+		msg.msg_control = NULL;
+		msg.msg_controllen = 0;
+		n = sendmsg(fd, &msg, 0);
+		if (CHECK(n <= 0, "sendmsg", "failed\n")) {
+			log_err("failed to send echo reply");
+			close(fd);
+			return -1;
+		}
+
+		close(fd);
+	}
 }
 
 static int tcp_echo_test(int client_fd, int server_fd)
@@ -454,14 +470,14 @@ static int tcp_echo_test(int client_fd, int server_fd)
 	return 0;
 }
 
-static int udp_echo_test(int client_fd, int server_fd)
+static int udp_echo_test(int client_fd, int server_fd, bool dont_bind_reply)
 {
 	int err;
 
 	err = send_byte(client_fd);
 	if (err)
 		return -1;
-	err = udp_recv_send(server_fd);
+	err = udp_recv_send(server_fd, dont_bind_reply);
 	if (err)
 		return -1;
 	err = recv_byte(client_fd);
@@ -653,7 +669,7 @@ static void run_lookup_prog(const struct test *t)
 	if (t->sotype == SOCK_STREAM)
 		tcp_echo_test(client_fd, server_fds[t->accept_on]);
 	else
-		udp_echo_test(client_fd, server_fds[t->accept_on]);
+		udp_echo_test(client_fd, server_fds[t->accept_on], t->dont_bind_reply);
 
 	close(client_fd);
 close:
@@ -775,6 +791,16 @@ static void test_redirect_lookup(struct test_sk_lookup *skel)
 			.listen_at	= { INT_IP4, INT_PORT },
 			.accept_on	= SERVER_B,
 		},
+		{
+			.desc		= "UDP IPv4 redir different ports",
+			.lookup_prog	= skel->progs.select_sock_a_no_reuseport,
+			.sock_map	= skel->maps.redir_map,
+			.sotype		= SOCK_DGRAM,
+			.connect_to	= { EXT_IP4, EXT_PORT },
+			.listen_at	= { INT_IP4, INT_PORT },
+			.accept_on	= SERVER_A,
+			.dont_bind_reply = true,
+		},
 		{
 			.desc		= "UDP IPv4 redir and reuseport with conns",
 			.lookup_prog	= skel->progs.select_sock_a,

-- 
2.34.1
Re: [RFC PATCH 3/3] bpf: Add sk_lookup test to use ORIGDSTADDR cmsg.
Posted by Philo Lu 2 months, 2 weeks ago 
Hi Tiago,

On 2024/9/13 17:39, Tiago Lam wrote:
> This patch reuses the framework already in place for sk_lookup, allowing
> it now to send a reply from the server fd directly, instead of having to
> create a socket bound to the original destination address and reply from
> there. It does this by passing the source address and port from where to
> reply from in a IP_ORIGDSTADDR ancilliary message passed in sendmsg.
> 
> Signed-off-by: Tiago Lam <tiagolam@cloudflare.com>
> ---
>   tools/testing/selftests/bpf/prog_tests/sk_lookup.c | 70 +++++++++++++++-------
>   1 file changed, 48 insertions(+), 22 deletions(-)
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
> index ae87c00867ba..b99aff2e3976 100644
> --- a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
> +++ b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
> @@ -75,6 +75,7 @@ struct test {
>   	struct inet_addr listen_at;
>   	enum server accept_on;
>   	bool reuseport_has_conns; /* Add a connected socket to reuseport group */
> +	bool dont_bind_reply; /* Don't bind, send direct from server fd. */
>   };
>   
>   struct cb_opts {
> @@ -363,7 +364,7 @@ static void v4_to_v6(struct sockaddr_storage *ss)
>   	memset(&v6->sin6_addr.s6_addr[0], 0, 10);
>   }
>   
> -static int udp_recv_send(int server_fd)
> +static int udp_recv_send(int server_fd, bool dont_bind_reply)
>   {
>   	char cmsg_buf[CMSG_SPACE(sizeof(struct sockaddr_storage))];
>   	struct sockaddr_storage _src_addr = { 0 };
> @@ -415,26 +416,41 @@ static int udp_recv_send(int server_fd)
>   		v4_to_v6(dst_addr);
>   	}
>   
> -	/* Reply from original destination address. */
> -	fd = start_server_addr(SOCK_DGRAM, dst_addr, sizeof(*dst_addr), NULL);
> -	if (!ASSERT_OK_FD(fd, "start_server_addr")) {
> -		log_err("failed to create tx socket");
> -		return -1;
> -	}
> +	if (dont_bind_reply) {
> +		/* Reply directly from server fd, specifying the source address and/or
> +		 * port in struct msghdr.
> +		 */
> +		n = sendmsg(server_fd, &msg, 0);
> +		if (CHECK(n <= 0, "sendmsg", "failed\n")) {
> +			log_err("failed to send echo reply");
> +			return -1;
> +		}
> +	} else {
> +		/* Reply from original destination address. */
> +		fd = socket(dst_addr->ss_family, SOCK_DGRAM, 0);
> +		if (CHECK(fd < 0, "socket", "failed\n")) {
> +			log_err("failed to create tx socket");
> +			return -1;
> +		}
>   
Just curious, why not use start_server_addr() here like before?

> -	msg.msg_control = NULL;
> -	msg.msg_controllen = 0;
> -	n = sendmsg(fd, &msg, 0);
> -	if (CHECK(n <= 0, "sendmsg", "failed\n")) {
> -		log_err("failed to send echo reply");
> -		ret = -1;
> -		goto out;
> -	}
> +		ret = bind(fd, (struct sockaddr *)dst_addr, sizeof(*dst_addr));
> +		if (CHECK(ret, "bind", "failed\n")) {
> +			log_err("failed to bind tx socket");
> +			close(fd);
> +			return ret;
> +		}
>   
> -	ret = 0;
> -out:
> -	close(fd);
> -	return ret;
> +		msg.msg_control = NULL;
> +		msg.msg_controllen = 0;
> +		n = sendmsg(fd, &msg, 0);
> +		if (CHECK(n <= 0, "sendmsg", "failed\n")) {
> +			log_err("failed to send echo reply");
> +			close(fd);
> +			return -1;
> +		}
> +
> +		close(fd);
> +	}

nit: "return 0" missed.

>   }
>   

-- 
Philo
Re: [RFC PATCH 3/3] bpf: Add sk_lookup test to use ORIGDSTADDR cmsg.
Posted by Tiago Lam 2 months, 1 week ago 
On Fri, Sep 13, 2024 at 08:10:24PM +0800, Philo Lu wrote:
> Hi Tiago,
> 
> On 2024/9/13 17:39, Tiago Lam wrote:
> > This patch reuses the framework already in place for sk_lookup, allowing
> > it now to send a reply from the server fd directly, instead of having to
> > create a socket bound to the original destination address and reply from
> > there. It does this by passing the source address and port from where to
> > reply from in a IP_ORIGDSTADDR ancilliary message passed in sendmsg.
> > 
> > Signed-off-by: Tiago Lam <tiagolam@cloudflare.com>
> > ---
> >   tools/testing/selftests/bpf/prog_tests/sk_lookup.c | 70 +++++++++++++++-------
> >   1 file changed, 48 insertions(+), 22 deletions(-)
> > 
> > diff --git a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
> > index ae87c00867ba..b99aff2e3976 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
> > @@ -75,6 +75,7 @@ struct test {
> >   	struct inet_addr listen_at;
> >   	enum server accept_on;
> >   	bool reuseport_has_conns; /* Add a connected socket to reuseport group */
> > +	bool dont_bind_reply; /* Don't bind, send direct from server fd. */
> >   };
> >   struct cb_opts {
> > @@ -363,7 +364,7 @@ static void v4_to_v6(struct sockaddr_storage *ss)
> >   	memset(&v6->sin6_addr.s6_addr[0], 0, 10);
> >   }
> > -static int udp_recv_send(int server_fd)
> > +static int udp_recv_send(int server_fd, bool dont_bind_reply)
> >   {
> >   	char cmsg_buf[CMSG_SPACE(sizeof(struct sockaddr_storage))];
> >   	struct sockaddr_storage _src_addr = { 0 };
> > @@ -415,26 +416,41 @@ static int udp_recv_send(int server_fd)
> >   		v4_to_v6(dst_addr);
> >   	}
> > -	/* Reply from original destination address. */
> > -	fd = start_server_addr(SOCK_DGRAM, dst_addr, sizeof(*dst_addr), NULL);
> > -	if (!ASSERT_OK_FD(fd, "start_server_addr")) {
> > -		log_err("failed to create tx socket");
> > -		return -1;
> > -	}
> > +	if (dont_bind_reply) {
> > +		/* Reply directly from server fd, specifying the source address and/or
> > +		 * port in struct msghdr.
> > +		 */
> > +		n = sendmsg(server_fd, &msg, 0);
> > +		if (CHECK(n <= 0, "sendmsg", "failed\n")) {
> > +			log_err("failed to send echo reply");
> > +			return -1;
> > +		}
> > +	} else {
> > +		/* Reply from original destination address. */
> > +		fd = socket(dst_addr->ss_family, SOCK_DGRAM, 0);
> > +		if (CHECK(fd < 0, "socket", "failed\n")) {
> > +			log_err("failed to create tx socket");
> > +			return -1;
> > +		}
> Just curious, why not use start_server_addr() here like before?
> 

Thanks, you're right. Initially I rebased this on commit
e3d332aaf898ed755b29c8cdf59be2cfba1cac4b (v6.6.31), which didn't have
start_server_addr(), and used bind() instead. I must have messed up the
rebased.

I've fixed this and included your other suggestion in the patch below
and will fold it into the next revision.

diff --git a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
index b99aff2e3976..0628a67681c5 100644
--- a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
+++ b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
@@ -374,7 +374,7 @@ static int udp_recv_send(int server_fd, bool dont_bind_reply)
        struct iovec iov = { 0 };
        struct cmsghdr *cm;
        char buf[1];
-       int ret, fd;
+       int fd;
        ssize_t n;
 
        iov.iov_base = buf;
@@ -427,19 +427,12 @@ static int udp_recv_send(int server_fd, bool dont_bind_reply)
                }
        } else {
                /* Reply from original destination address. */
-               fd = socket(dst_addr->ss_family, SOCK_DGRAM, 0);
-               if (CHECK(fd < 0, "socket", "failed\n")) {
+               fd = start_server_addr(SOCK_DGRAM, dst_addr, sizeof(*dst_addr), NULL);
+               if (!ASSERT_OK_FD(fd, "start_server_addr")) {
                        log_err("failed to create tx socket");
                        return -1;
                }
 
-               ret = bind(fd, (struct sockaddr *)dst_addr, sizeof(*dst_addr));
-               if (CHECK(ret, "bind", "failed\n")) {
-                       log_err("failed to bind tx socket");
-                       close(fd);
-                       return ret;
-               }
-
                msg.msg_control = NULL;
                msg.msg_controllen = 0;
                n = sendmsg(fd, &msg, 0);
@@ -451,6 +444,8 @@ static int udp_recv_send(int server_fd, bool dont_bind_reply)
 
                close(fd);
        }
+
+       return 0;
 }
 
 static int tcp_echo_test(int client_fd, int server_fd)

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