netdev - [PATCH iproute2 net-next v2 1/2] iplink

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Message-Id: <869ad3a59a4840970514a201d5f801c6db676d6d.1541641480.git.sbrivio@redhat.com>
Date:   Thu,  8 Nov 2018 12:21:25 +0100
From:   Stefano Brivio <sbrivio@...hat.com>
To:     David Ahern <dsahern@...il.com>
Cc:     Stephen Hemminger <stephen@...workplumber.org>,
        netdev@...r.kernel.org
Subject: [PATCH iproute2 net-next v2 1/2] iplink_vxlan: Add DF configuration

Allow to set the DF bit behaviour for outgoing IPv4 packets: it can be
always on, inherited from the inner header, or, by default, always off,
which is the current behaviour.

v2:
- Indicate in the man page what DF refers to, using RFC 791 wording
  (David Ahern)

Signed-off-by: Stefano Brivio <sbrivio@...hat.com>
---
 include/uapi/linux/if_link.h |  9 +++++++++
 ip/iplink_vxlan.c            | 29 +++++++++++++++++++++++++++++
 man/man8/ip-link.8.in        | 14 ++++++++++++++
 3 files changed, 52 insertions(+)

diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 9c254603ebda..4caf683ce546 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -530,6 +530,7 @@ enum {
 	IFLA_VXLAN_LABEL,
 	IFLA_VXLAN_GPE,
 	IFLA_VXLAN_TTL_INHERIT,
+	IFLA_VXLAN_DF,
 	__IFLA_VXLAN_MAX
 };
 #define IFLA_VXLAN_MAX	(__IFLA_VXLAN_MAX - 1)
@@ -539,6 +540,14 @@ struct ifla_vxlan_port_range {
 	__be16	high;
 };
 
+enum ifla_vxlan_df {
+	VXLAN_DF_UNSET = 0,
+	VXLAN_DF_SET,
+	VXLAN_DF_INHERIT,
+	__VXLAN_DF_END,
+	VXLAN_DF_MAX = __VXLAN_DF_END - 1,
+};
+
 /* GENEVE section */
 enum {
 	IFLA_GENEVE_UNSPEC,
diff --git a/ip/iplink_vxlan.c b/ip/iplink_vxlan.c
index 7fc0e2b4eb06..86afbe1334f0 100644
--- a/ip/iplink_vxlan.c
+++ b/ip/iplink_vxlan.c
@@ -31,6 +31,7 @@ static void print_explain(FILE *f)
 		"                 [ local ADDR ]\n"
 		"                 [ ttl TTL ]\n"
 		"                 [ tos TOS ]\n"
+		"                 [ df DF ]\n"
 		"                 [ flowlabel LABEL ]\n"
 		"                 [ dev PHYS_DEV ]\n"
 		"                 [ dstport PORT ]\n"
@@ -52,6 +53,7 @@ static void print_explain(FILE *f)
 		"       ADDR  := { IP_ADDRESS | any }\n"
 		"       TOS   := { NUMBER | inherit }\n"
 		"       TTL   := { 1..255 | auto | inherit }\n"
+		"       DF    := { unset | set | inherit }\n"
 		"       LABEL := 0-1048575\n"
 	);
 }
@@ -170,6 +172,22 @@ static int vxlan_parse_opt(struct link_util *lu, int argc, char **argv,
 			} else
 				tos = 1;
 			addattr8(n, 1024, IFLA_VXLAN_TOS, tos);
+		} else if (!matches(*argv, "df")) {
+			enum ifla_vxlan_df df;
+
+			NEXT_ARG();
+			check_duparg(&attrs, IFLA_VXLAN_DF, "df", *argv);
+			if (strcmp(*argv, "unset") == 0)
+				df = VXLAN_DF_UNSET;
+			else if (strcmp(*argv, "set") == 0)
+				df = VXLAN_DF_SET;
+			else if (strcmp(*argv, "inherit") == 0)
+				df = VXLAN_DF_INHERIT;
+			else
+				invarg("DF must be 'unset', 'set' or 'inherit'",
+				       *argv);
+
+			addattr8(n, 1024, IFLA_VXLAN_DF, df);
 		} else if (!matches(*argv, "label") ||
 			   !matches(*argv, "flowlabel")) {
 			__u32 uval;
@@ -538,6 +556,17 @@ static void vxlan_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
 			print_string(PRINT_FP, NULL, "ttl %s ", "auto");
 	}
 
+	if (tb[IFLA_VXLAN_DF]) {
+		enum ifla_vxlan_df df = rta_getattr_u8(tb[IFLA_VXLAN_DF]);
+
+		if (df == VXLAN_DF_UNSET)
+			print_string(PRINT_JSON, "df", "df %s ", "unset");
+		else if (df == VXLAN_DF_SET)
+			print_string(PRINT_ANY, "df", "df %s ", "set");
+		else if (df == VXLAN_DF_INHERIT)
+			print_string(PRINT_ANY, "df", "df %s ", "inherit");
+	}
+
 	if (tb[IFLA_VXLAN_LABEL]) {
 		__u32 label = rta_getattr_u32(tb[IFLA_VXLAN_LABEL]);
 
diff --git a/man/man8/ip-link.8.in b/man/man8/ip-link.8.in
index 5132f514b279..a94cf4f19f1e 100644
--- a/man/man8/ip-link.8.in
+++ b/man/man8/ip-link.8.in
@@ -496,6 +496,8 @@ the following additional arguments are supported:
 ] [
 .BI tos " TOS "
 ] [
+.BI df " DF "
+] [
 .BI flowlabel " FLOWLABEL "
 ] [
 .BI dstport " PORT "
@@ -565,6 +567,18 @@ parameter.
 .BI tos " TOS"
 - specifies the TOS value to use in outgoing packets.
 
+.sp
+.BI df " DF"
+- specifies the usage of the Don't Fragment flag (DF) bit in outgoing packets
+with IPv4 headers. The value
+.B inherit
+causes the bit to be copied from the original IP header. The values
+.B unset
+and
+.B set
+cause the bit to be always unset or always set, respectively. By default, the
+bit is not set.
+
 .sp
 .BI flowlabel " FLOWLABEL"
 - specifies the flow label to use in outgoing packets.
-- 
2.19.1