[PATCH iproute2-next v2] ip-link: add support for nolocalbypass in vxlan

[PATCH iproute2-next v2] ip-link: add support for nolocalbypass in vxlan

[Vladimir Nikishkin]

Add userspace support for the [no]localbypass vxlan netlink
attribute. With localbypass on (default), the vxlan driver processes
the packets destined to the local machine by itself, bypassing the
nework stack. With nolocalbypass the packets are always forwarded to
the userspace network stack, so usepspace programs, such as tcpdump
have a chance to process them.

Signed-off-by: Vladimir Nikishkin <vladimir@nikishkin.pw>
---
v2: this patch matches commit 69474a8a5837be63f13c6f60a7d622b98ed5c539
in the main tree.

 ip/iplink_vxlan.c     | 19 +++++++++++++++++++
 man/man8/ip-link.8.in | 10 ++++++++++
 2 files changed, 29 insertions(+)

diff --git a/ip/iplink_vxlan.c b/ip/iplink_vxlan.c
index c7e0e1c4..98fbc65c 100644
--- a/ip/iplink_vxlan.c
+++ b/ip/iplink_vxlan.c
@@ -45,6 +45,7 @@ static void print_explain(FILE *f)
 		"		[ [no]remcsumtx ] [ [no]remcsumrx ]\n"
 		"		[ [no]external ] [ gbp ] [ gpe ]\n"
 		"		[ [no]vnifilter ]\n"
+		"		[ [no]localbypass ]\n"
 		"\n"
 		"Where:	VNI	:= 0-16777215\n"
 		"	ADDR	:= { IP_ADDRESS | any }\n"
@@ -276,6 +277,12 @@ static int vxlan_parse_opt(struct link_util *lu, int argc, char **argv,
 		} else if (!matches(*argv, "noudpcsum")) {
 			check_duparg(&attrs, IFLA_VXLAN_UDP_CSUM, *argv, *argv);
 			addattr8(n, 1024, IFLA_VXLAN_UDP_CSUM, 0);
+		} else if (0 == strcmp(*argv, "localbypass")) {
+			check_duparg(&attrs, IFLA_VXLAN_LOCALBYPASS, *argv, *argv);
+			addattr8(n, 1024, IFLA_VXLAN_LOCALBYPASS, 1);
+		} else if (0 == strcmp(*argv, "nolocalbypass")) {
+			check_duparg(&attrs, IFLA_VXLAN_LOCALBYPASS, *argv, *argv);
+			addattr8(n, 1024, IFLA_VXLAN_LOCALBYPASS, 0);
 		} else if (!matches(*argv, "udp6zerocsumtx")) {
 			check_duparg(&attrs, IFLA_VXLAN_UDP_ZERO_CSUM6_TX,
 				     *argv, *argv);
@@ -613,6 +620,18 @@ static void vxlan_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
 		}
 	}
 
+	if (tb[IFLA_VXLAN_LOCALBYPASS]) {
+		__u8 localbypass = rta_getattr_u8(tb[IFLA_VXLAN_LOCALBYPASS]);
+
+		if (is_json_context()) {
+			print_bool(PRINT_ANY, "localbypass", NULL, localbypass);
+		} else {
+			if (!localbypass)
+				fputs("no", f);
+			fputs("localbypass ", f);
+		}
+	}
+
 	if (tb[IFLA_VXLAN_UDP_ZERO_CSUM6_TX]) {
 		__u8 csum6 = rta_getattr_u8(tb[IFLA_VXLAN_UDP_ZERO_CSUM6_TX]);
 
diff --git a/man/man8/ip-link.8.in b/man/man8/ip-link.8.in
index bf3605a9..e53efc45 100644
--- a/man/man8/ip-link.8.in
+++ b/man/man8/ip-link.8.in
@@ -630,6 +630,8 @@ the following additional arguments are supported:
 ] [
 .RB [ no ] udpcsum
 ] [
+.RB [ no ] localbypass
+] [
 .RB [ no ] udp6zerocsumtx
 ] [
 .RB [ no ] udp6zerocsumrx
@@ -734,6 +736,14 @@ are entered into the VXLAN device forwarding database.
 .RB [ no ] udpcsum
 - specifies if UDP checksum is calculated for transmitted packets over IPv4.
 
+.sp
+.RB [ no ] localbypass
+- if fdb destination is local, with nolocalbypass set, forward packets
+to the userspace network stack. If there is a userspace process
+listening for these packets, it will have a chance to process them.
+If localbypass is active (default), bypass the network stack and
+inject the packet into the driver directly.
+
 .sp
 .RB [ no ] udp6zerocsumtx
 - skip UDP checksum calculation for transmitted packets over IPv6.
-- 
2.35.8

--
Fastmail.

Re: [PATCH iproute2-next v2] ip-link: add support for nolocalbypass in vxlan

[Ido Schimmel]

On Tue, May 16, 2023 at 10:04:57PM +0800, Vladimir Nikishkin wrote:
> Add userspace support for the [no]localbypass vxlan netlink
> attribute. With localbypass on (default), the vxlan driver processes
> the packets destined to the local machine by itself, bypassing the
> nework stack. With nolocalbypass the packets are always forwarded to
> the userspace network stack, so usepspace programs, such as tcpdump

s/usepspace/userspace/

> have a chance to process them.
> 
> Signed-off-by: Vladimir Nikishkin <vladimir@nikishkin.pw>
> ---
> v2: this patch matches commit 69474a8a5837be63f13c6f60a7d622b98ed5c539
> in the main tree.
> 
>  ip/iplink_vxlan.c     | 19 +++++++++++++++++++
>  man/man8/ip-link.8.in | 10 ++++++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/ip/iplink_vxlan.c b/ip/iplink_vxlan.c
> index c7e0e1c4..98fbc65c 100644
> --- a/ip/iplink_vxlan.c
> +++ b/ip/iplink_vxlan.c
> @@ -45,6 +45,7 @@ static void print_explain(FILE *f)
>  		"		[ [no]remcsumtx ] [ [no]remcsumrx ]\n"
>  		"		[ [no]external ] [ gbp ] [ gpe ]\n"
>  		"		[ [no]vnifilter ]\n"
> +		"		[ [no]localbypass ]\n"
>  		"\n"
>  		"Where:	VNI	:= 0-16777215\n"
>  		"	ADDR	:= { IP_ADDRESS | any }\n"
> @@ -276,6 +277,12 @@ static int vxlan_parse_opt(struct link_util *lu, int argc, char **argv,
>  		} else if (!matches(*argv, "noudpcsum")) {
>  			check_duparg(&attrs, IFLA_VXLAN_UDP_CSUM, *argv, *argv);
>  			addattr8(n, 1024, IFLA_VXLAN_UDP_CSUM, 0);
> +		} else if (0 == strcmp(*argv, "localbypass")) {

To be consistent with other strcmp() instances in this file, please
either use '!strcmp()' or 'strcmp() == 0'

> +			check_duparg(&attrs, IFLA_VXLAN_LOCALBYPASS, *argv, *argv);

Make this fit in 80 chars like other options

> +			addattr8(n, 1024, IFLA_VXLAN_LOCALBYPASS, 1);
> +		} else if (0 == strcmp(*argv, "nolocalbypass")) {
> +			check_duparg(&attrs, IFLA_VXLAN_LOCALBYPASS, *argv, *argv);

Likewise

> +			addattr8(n, 1024, IFLA_VXLAN_LOCALBYPASS, 0);
>  		} else if (!matches(*argv, "udp6zerocsumtx")) {
>  			check_duparg(&attrs, IFLA_VXLAN_UDP_ZERO_CSUM6_TX,
>  				     *argv, *argv);
> @@ -613,6 +620,18 @@ static void vxlan_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
>  		}
>  	}
>  
> +	if (tb[IFLA_VXLAN_LOCALBYPASS]) {
> +		__u8 localbypass = rta_getattr_u8(tb[IFLA_VXLAN_LOCALBYPASS]);
> +
> +		if (is_json_context()) {
> +			print_bool(PRINT_ANY, "localbypass", NULL, localbypass);
> +		} else {
> +			if (!localbypass)
> +				fputs("no", f);
> +			fputs("localbypass ", f);
> +		}
> +	}
> +
>  	if (tb[IFLA_VXLAN_UDP_ZERO_CSUM6_TX]) {
>  		__u8 csum6 = rta_getattr_u8(tb[IFLA_VXLAN_UDP_ZERO_CSUM6_TX]);
>  
> diff --git a/man/man8/ip-link.8.in b/man/man8/ip-link.8.in
> index bf3605a9..e53efc45 100644
> --- a/man/man8/ip-link.8.in
> +++ b/man/man8/ip-link.8.in
> @@ -630,6 +630,8 @@ the following additional arguments are supported:
>  ] [
>  .RB [ no ] udpcsum
>  ] [
> +.RB [ no ] localbypass
> +] [
>  .RB [ no ] udp6zerocsumtx
>  ] [
>  .RB [ no ] udp6zerocsumrx
> @@ -734,6 +736,14 @@ are entered into the VXLAN device forwarding database.
>  .RB [ no ] udpcsum
>  - specifies if UDP checksum is calculated for transmitted packets over IPv4.
>  
> +.sp
> +.RB [ no ] localbypass
> +- if fdb destination is local, with nolocalbypass set, forward packets

s/fdb/FDB/

forward encapsulated packets

> +to the userspace network stack. If there is a userspace process
> +listening for these packets, it will have a chance to process them.
> +If localbypass is active (default), bypass the network stack and

bypass the kernel network stack (since you mentioned "userspace network
stack" earlier)

> +inject the packet into the driver directly.

inject the packets to the target VXLAN device, assuming one exists.


> +
>  .sp
>  .RB [ no ] udp6zerocsumtx
>  - skip UDP checksum calculation for transmitted packets over IPv6.
> -- 
> 2.35.8
> 
> --
> Fastmail.
> 
> 

Re: [PATCH iproute2-next v2] ip-link: add support for nolocalbypass in vxlan

[Andrea Claudi]

On Tue, May 16, 2023 at 10:04:57PM +0800, Vladimir Nikishkin wrote:
> Add userspace support for the [no]localbypass vxlan netlink
> attribute. With localbypass on (default), the vxlan driver processes
> the packets destined to the local machine by itself, bypassing the
> nework stack. With nolocalbypass the packets are always forwarded to
> the userspace network stack, so usepspace programs, such as tcpdump
> have a chance to process them.
> 
> Signed-off-by: Vladimir Nikishkin <vladimir@nikishkin.pw>
> ---
> v2: this patch matches commit 69474a8a5837be63f13c6f60a7d622b98ed5c539
> in the main tree.
> 
>  ip/iplink_vxlan.c     | 19 +++++++++++++++++++
>  man/man8/ip-link.8.in | 10 ++++++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/ip/iplink_vxlan.c b/ip/iplink_vxlan.c
> index c7e0e1c4..98fbc65c 100644
> --- a/ip/iplink_vxlan.c
> +++ b/ip/iplink_vxlan.c
> @@ -45,6 +45,7 @@ static void print_explain(FILE *f)
>  		"		[ [no]remcsumtx ] [ [no]remcsumrx ]\n"
>  		"		[ [no]external ] [ gbp ] [ gpe ]\n"
>  		"		[ [no]vnifilter ]\n"
> +		"		[ [no]localbypass ]\n"
>  		"\n"
>  		"Where:	VNI	:= 0-16777215\n"
>  		"	ADDR	:= { IP_ADDRESS | any }\n"
> @@ -276,6 +277,12 @@ static int vxlan_parse_opt(struct link_util *lu, int argc, char **argv,
>  		} else if (!matches(*argv, "noudpcsum")) {
>  			check_duparg(&attrs, IFLA_VXLAN_UDP_CSUM, *argv, *argv);
>  			addattr8(n, 1024, IFLA_VXLAN_UDP_CSUM, 0);
> +		} else if (0 == strcmp(*argv, "localbypass")) {
> +			check_duparg(&attrs, IFLA_VXLAN_LOCALBYPASS, *argv, *argv);
> +			addattr8(n, 1024, IFLA_VXLAN_LOCALBYPASS, 1);
> +		} else if (0 == strcmp(*argv, "nolocalbypass")) {
> +			check_duparg(&attrs, IFLA_VXLAN_LOCALBYPASS, *argv, *argv);
> +			addattr8(n, 1024, IFLA_VXLAN_LOCALBYPASS, 0);
>  		} else if (!matches(*argv, "udp6zerocsumtx")) {
>  			check_duparg(&attrs, IFLA_VXLAN_UDP_ZERO_CSUM6_TX,
>  				     *argv, *argv);
> @@ -613,6 +620,18 @@ static void vxlan_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
>  		}
>  	}
>  
> +	if (tb[IFLA_VXLAN_LOCALBYPASS]) {
> +		__u8 localbypass = rta_getattr_u8(tb[IFLA_VXLAN_LOCALBYPASS]);
> +
> +		if (is_json_context()) {
> +			print_bool(PRINT_ANY, "localbypass", NULL, localbypass);
> +		} else {
> +			if (!localbypass)
> +				fputs("no", f);
> +			fputs("localbypass ", f);
> +		}

Please use print_* functions for non-json output, too.

Also, you don't need to use is_json_context() here, you can simply use
PRINT_JSON to ensure that info is printed only for json output.

Something like this should work:

+		print_bool(PRINT_JSON, "localbypass", NULL, localbypass);
+		if (localbypass) {
+			print_string(PRINT_FP, NULL, "localbypass ", NULL);
+		} else {
+			print_string(PRINT_FP, NULL, "nolocalbypass ", NULL);
+		}

> +	}
> +
>  	if (tb[IFLA_VXLAN_UDP_ZERO_CSUM6_TX]) {
>  		__u8 csum6 = rta_getattr_u8(tb[IFLA_VXLAN_UDP_ZERO_CSUM6_TX]);
>  
> diff --git a/man/man8/ip-link.8.in b/man/man8/ip-link.8.in
> index bf3605a9..e53efc45 100644
> --- a/man/man8/ip-link.8.in
> +++ b/man/man8/ip-link.8.in
> @@ -630,6 +630,8 @@ the following additional arguments are supported:
>  ] [
>  .RB [ no ] udpcsum
>  ] [
> +.RB [ no ] localbypass
> +] [
>  .RB [ no ] udp6zerocsumtx
>  ] [
>  .RB [ no ] udp6zerocsumrx
> @@ -734,6 +736,14 @@ are entered into the VXLAN device forwarding database.
>  .RB [ no ] udpcsum
>  - specifies if UDP checksum is calculated for transmitted packets over IPv4.
>  
> +.sp
> +.RB [ no ] localbypass
> +- if fdb destination is local, with nolocalbypass set, forward packets
> +to the userspace network stack. If there is a userspace process
> +listening for these packets, it will have a chance to process them.
> +If localbypass is active (default), bypass the network stack and
> +inject the packet into the driver directly.
> +
>  .sp
>  .RB [ no ] udp6zerocsumtx
>  - skip UDP checksum calculation for transmitted packets over IPv6.
> -- 
> 2.35.8
> 
> --
> Fastmail.
> 
>