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 <sbri...@redhat.com>
---
include/uapi/linux/if_link.h | 9 +++++++++
ip/iplink_geneve.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 4caf683ce546..183ca7527178 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -563,10 +563,19 @@ 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 c417842b2a5b..1872b74c5d70 100644
--- 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 a94cf4f19f1e..73d37c190fff 100644
--- 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.
--
2.19.1
