gre/gre6: allow clearing {,i,o}{key,seq,csum} flags

Currently, iproute allows setting those flags, but it's impossible to
clear them, since their current value is fetched from the kernel and
then we OR in the additional flags passed on the command line.

Add no* variants to allow clearing them.

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David Ahern <dsahern@gmail.com>

ip/link_gre.c

@@ -31,9 +31,9 @@ static void gre_print_help(struct link_util *lu, int argc, char **argv, FILE *f)
 	);
 	fprintf(f,
 		"                     [ local ADDR ]\n"
-		"                     [ [i|o]seq ]\n"
+		"                     [ [no][i|o]seq ]\n"
-		"                     [ [i|o]key KEY ]\n"
+		"                     [ [i|o]key KEY | no[i|o]key ]\n"
-		"                     [ [i|o]csum ]\n"
+		"                     [ [no][i|o]csum ]\n"
 		"                     [ ttl TTL ]\n"
 		"                     [ tos TOS ]\n"
 		"                     [ [no]pmtudisc ]\n"
@@ -210,28 +210,52 @@ get_failed:
 			iflags |= GRE_KEY;
 			oflags |= GRE_KEY;
 			ikey = okey = tnl_parse_key("key", *argv);
+		} else if (!matches(*argv, "nokey")) {
+			iflags &= ~GRE_KEY;
+			oflags &= ~GRE_KEY;
+			ikey = okey = 0;
 		} else if (!matches(*argv, "ikey")) {
 			NEXT_ARG();
 			iflags |= GRE_KEY;
 			ikey = tnl_parse_key("ikey", *argv);
+		} else if (!matches(*argv, "noikey")) {
+			iflags &= ~GRE_KEY;
+			ikey = 0;
 		} else if (!matches(*argv, "okey")) {
 			NEXT_ARG();
 			oflags |= GRE_KEY;
 			okey = tnl_parse_key("okey", *argv);
+		} else if (!matches(*argv, "nookey")) {
+			oflags &= ~GRE_KEY;
+			okey = 0;
 		} else if (!matches(*argv, "seq")) {
 			iflags |= GRE_SEQ;
 			oflags |= GRE_SEQ;
+		} else if (!matches(*argv, "noseq")) {
+			iflags &= ~GRE_SEQ;
+			oflags &= ~GRE_SEQ;
 		} else if (!matches(*argv, "iseq")) {
 			iflags |= GRE_SEQ;
+		} else if (!matches(*argv, "noiseq")) {
+			iflags &= ~GRE_SEQ;
 		} else if (!matches(*argv, "oseq")) {
 			oflags |= GRE_SEQ;
+		} else if (!matches(*argv, "nooseq")) {
+			oflags &= ~GRE_SEQ;
 		} else if (!matches(*argv, "csum")) {
 			iflags |= GRE_CSUM;
 			oflags |= GRE_CSUM;
+		} else if (!matches(*argv, "nocsum")) {
+			iflags &= ~GRE_CSUM;
+			oflags &= ~GRE_CSUM;
 		} else if (!matches(*argv, "icsum")) {
 			iflags |= GRE_CSUM;
+		} else if (!matches(*argv, "noicsum")) {
+			iflags &= ~GRE_CSUM;
 		} else if (!matches(*argv, "ocsum")) {
 			oflags |= GRE_CSUM;
+		} else if (!matches(*argv, "noocsum")) {
+			oflags &= ~GRE_CSUM;
 		} else if (!matches(*argv, "nopmtudisc")) {
 			pmtudisc = 0;
 		} else if (!matches(*argv, "pmtudisc")) {

ip/link_gre6.c

@@ -38,9 +38,9 @@ static void gre_print_help(struct link_util *lu, int argc, char **argv, FILE *f)
 	);
 	fprintf(f,
 		"                     [ local ADDR ]\n"
-		"                     [ [i|o]seq ]\n"
+		"                     [ [no][i|o]seq ]\n"
-		"                     [ [i|o]key KEY ]\n"
+		"                     [ [i|o]key KEY | no[i|o]key ]\n"
-		"                     [ [i|o]csum ]\n"
+		"                     [ [no][i|o]csum ]\n"
 		"                     [ hoplimit TTL ]\n"
 		"                     [ encaplimit ELIM ]\n"
 		"                     [ tclass TCLASS ]\n"
@@ -220,28 +220,52 @@ get_failed:
 			iflags |= GRE_KEY;
 			oflags |= GRE_KEY;
 			ikey = okey = tnl_parse_key("key", *argv);
+		} else if (!matches(*argv, "nokey")) {
+			iflags &= ~GRE_KEY;
+			oflags &= ~GRE_KEY;
+			ikey = okey = 0;
 		} else if (!matches(*argv, "ikey")) {
 			NEXT_ARG();
 			iflags |= GRE_KEY;
 			ikey = tnl_parse_key("ikey", *argv);
+		} else if (!matches(*argv, "noikey")) {
+			iflags &= ~GRE_KEY;
+			ikey = 0;
 		} else if (!matches(*argv, "okey")) {
 			NEXT_ARG();
 			oflags |= GRE_KEY;
 			okey = tnl_parse_key("okey", *argv);
+		} else if (!matches(*argv, "nookey")) {
+			oflags &= ~GRE_KEY;
+			okey = 0;
 		} else if (!matches(*argv, "seq")) {
 			iflags |= GRE_SEQ;
 			oflags |= GRE_SEQ;
+		} else if (!matches(*argv, "noseq")) {
+			iflags &= ~GRE_SEQ;
+			oflags &= ~GRE_SEQ;
 		} else if (!matches(*argv, "iseq")) {
 			iflags |= GRE_SEQ;
+		} else if (!matches(*argv, "noiseq")) {
+			iflags &= ~GRE_SEQ;
 		} else if (!matches(*argv, "oseq")) {
 			oflags |= GRE_SEQ;
+		} else if (!matches(*argv, "nooseq")) {
+			oflags &= ~GRE_SEQ;
 		} else if (!matches(*argv, "csum")) {
 			iflags |= GRE_CSUM;
 			oflags |= GRE_CSUM;
+		} else if (!matches(*argv, "nocsum")) {
+			iflags &= ~GRE_CSUM;
+			oflags &= ~GRE_CSUM;
 		} else if (!matches(*argv, "icsum")) {
 			iflags |= GRE_CSUM;
+		} else if (!matches(*argv, "noicsum")) {
+			iflags &= ~GRE_CSUM;
 		} else if (!matches(*argv, "ocsum")) {
 			oflags |= GRE_CSUM;
+		} else if (!matches(*argv, "noocsum")) {
+			oflags &= ~GRE_CSUM;
 		} else if (!matches(*argv, "remote")) {
 			NEXT_ARG();
 			get_addr(&daddr, *argv, AF_INET6);

man/man8/ip-link.8.in

@@ -775,12 +775,14 @@ the following additional arguments are supported:
 .BR type " { " gre " | " gretap " }"
 .BI " remote " ADDR " local " ADDR
 [
-.RB [ i | o ] seq
+.RB [ no ] "" [ i | o ] seq
 ] [
 .RB [ i | o ] key
 .I KEY
+|
+.BR no [ i | o ] key
 ] [
-.RB [ i | o ] csum
+.RB [ no ] "" [ i | o ] csum
 ] [
 .BI ttl " TTL "
 ] [
@@ -816,7 +818,7 @@ the following additional arguments are supported:
 It must be an address on another interface on this host.
 
 .sp
-.RB [ i | o ] seq
+.RB  [ no ] "" [ i | o ] seq
 - serialize packets.
 The
 .B oseq
@@ -828,6 +830,8 @@ flag requires that all input packets are serialized.
 .sp
 .RB [ i | o ] key
 .I KEY
+|
+.BR no [ i | o ] key
 - use keyed GRE with key
 .IR KEY ". "KEY
 is either a number or an IPv4 address-like dotted quad.
@@ -839,7 +843,7 @@ The
 parameters specify different keys for input and output.
 
 .sp
-.RB  [ i | o ] csum
+.RB  [ no ] "" [ i | o ] csum
 - generate/require checksums for tunneled packets.
 The
 .B ocsum
@@ -920,12 +924,14 @@ the following additional arguments are supported:
 .BR type " { " ip6gre " | " ip6gretap " }"
 .BI remote " ADDR " local " ADDR"
 [
-.RB [ i | o ] seq
+.RB [ no ] "" [ i | o ] seq
 ] [
 .RB [ i | o ] key
 .I KEY
+|
+.BR no [ i | o ] key
 ] [
-.RB [ i | o ] csum
+.RB [ no ] "" [ i | o ] csum
 ] [
 .BI hoplimit " TTL "
 ] [
@@ -955,7 +961,7 @@ the following additional arguments are supported:
 It must be an address on another interface on this host.
 
 .sp
-.RB  [ i | o ] seq
+.RB  [ no ] "" [ i | o ] seq
 - serialize packets.
 The
 .B oseq
@@ -965,7 +971,10 @@ The
 flag requires that all input packets are serialized.
 
 .sp
-.RB  [ i | o ] key " \fIKEY"
+.RB [ i | o ] key
+.I KEY
+|
+.BR no [ i | o ] key
 - use keyed GRE with key
 .IR KEY ". "KEY
 is either a number or an IPv4 address-like dotted quad.
@@ -977,7 +986,7 @@ The
 parameters specify different keys for input and output.
 
 .sp
-.RB  [ i | o ] csum
+.RB  [ no ] "" [ i | o ] csum
 - generate/require checksums for tunneled packets.
 The
 .B ocsum