iplink_geneve: 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@redhat.com>
Signed-off-by: David Ahern <dsahern@gmail.com>

diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 52512202476e36daf0f98a9f06c5ad041c2feb38..e1ef848aed011d3fc4f7cbefb30ee528c0a027bc 100644 (file)
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -564,10 +564,19 @@ enum {
        IFLA_GENEVE_UDP_ZERO_CSUM6_RX,
        IFLA_GENEVE_LABEL,
        IFLA_GENEVE_TTL_INHERIT,
+       IFLA_GENEVE_DF,
        __IFLA_GENEVE_MAX
 };
 #define IFLA_GENEVE_MAX        (__IFLA_GENEVE_MAX - 1)
 
+enum ifla_geneve_df {
+       GENEVE_DF_UNSET = 0,
+       GENEVE_DF_SET,
+       GENEVE_DF_INHERIT,
+       __GENEVE_DF_END,
+       GENEVE_DF_MAX = __GENEVE_DF_END - 1,
+};
+
 /* PPP section */
 enum {
        IFLA_PPP_UNSPEC,

diff --git a/ip/iplink_geneve.c b/ip/iplink_geneve.c
index c417842b2a5b58f63b1147fd02283c03d451829a..1872b74c5d701170869af966ac9b331614a9501f 100644 (file)
--- a/ip/iplink_geneve.c
+++ b/ip/iplink_geneve.c
@@ -24,6 +24,7 @@ static void print_explain(FILE *f)
                "                  remote ADDR\n"
                "                  [ ttl TTL ]\n"
                "                  [ tos TOS ]\n"
+               "                  [ df DF ]\n"
                "                  [ flowlabel LABEL ]\n"
                "                  [ dstport PORT ]\n"
                "                  [ [no]external ]\n"
@@ -35,6 +36,7 @@ static void print_explain(FILE *f)
                "       ADDR  := IP_ADDRESS\n"
                "       TOS   := { NUMBER | inherit }\n"
                "       TTL   := { 1..255 | auto | inherit }\n"
+               "       DF    := { unset | set | inherit }\n"
                "       LABEL := 0-1048575\n"
        );
 }
@@ -115,6 +117,22 @@ static int geneve_parse_opt(struct link_util *lu, int argc, char **argv,
                                tos = uval;
                        } else
                                tos = 1;
+               } else if (!matches(*argv, "df")) {
+                       enum ifla_geneve_df df;
+
+                       NEXT_ARG();
+                       check_duparg(&attrs, IFLA_GENEVE_DF, "df", *argv);
+                       if (strcmp(*argv, "unset") == 0)
+                               df = GENEVE_DF_UNSET;
+                       else if (strcmp(*argv, "set") == 0)
+                               df = GENEVE_DF_SET;
+                       else if (strcmp(*argv, "inherit") == 0)
+                               df = GENEVE_DF_INHERIT;
+                       else
+                               invarg("DF must be 'unset', 'set' or 'inherit'",
+                                      *argv);
+
+                       addattr8(n, 1024, IFLA_GENEVE_DF, df);
                } else if (!matches(*argv, "label") ||
                           !matches(*argv, "flowlabel")) {
                        __u32 uval;
@@ -287,6 +305,17 @@ static void geneve_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
                        print_string(PRINT_FP, NULL, "tos %s ", "inherit");
        }
 
+       if (tb[IFLA_GENEVE_DF]) {
+               enum ifla_geneve_df df = rta_getattr_u8(tb[IFLA_GENEVE_DF]);
+
+               if (df == GENEVE_DF_UNSET)
+                       print_string(PRINT_JSON, "df", "df %s ", "unset");
+               else if (df == GENEVE_DF_SET)
+                       print_string(PRINT_ANY, "df", "df %s ", "set");
+               else if (df == GENEVE_DF_INHERIT)
+                       print_string(PRINT_ANY, "df", "df %s ", "inherit");
+       }
+
        if (tb[IFLA_GENEVE_LABEL]) {
                __u32 label = rta_getattr_u32(tb[IFLA_GENEVE_LABEL]);
 

diff --git a/man/man8/ip-link.8.in b/man/man8/ip-link.8.in
index a94cf4f19f1e378086cd2c846408b7326f0ae0fc..73d37c190fffa638cd973cb00ede24ad2ac22732 100644 (file)
--- a/man/man8/ip-link.8.in
+++ b/man/man8/ip-link.8.in
@@ -1180,6 +1180,8 @@ the following additional arguments are supported:
 ] [
 .BI tos " TOS "
 ] [
+.BI df " DF "
+] [
 .BI flowlabel " FLOWLABEL "
 ] [
 .BI dstport " PORT"
@@ -1212,6 +1214,18 @@ ttl. Default option is "0".
 .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.