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Message-Id: <1475354917-7912-7-git-send-email-jhs@emojatatu.com>
Date: Sat, 1 Oct 2016 16:48:34 -0400
From: Jamal Hadi Salim <jhs@...atatu.com>
To: stephen@...workplumber.org
Cc: netdev@...r.kernel.org, Jamal Hadi Salim <jhs@...atatu.com>
Subject: [PATCH iproute2 6/9] actions: add skbmod action
From: Jamal Hadi Salim <jhs@...atatu.com>
This action is intended to be an upgrade from a usability perspective
from pedit (as well as operational debugability).
Compare this:
sudo tc filter add dev $ETH parent 1: protocol ip prio 10 \
u32 match ip protocol 1 0xff flowid 1:2 \
action pedit munge offset -14 u8 set 0x02 \
munge offset -13 u8 set 0x15 \
munge offset -12 u8 set 0x15 \
munge offset -11 u8 set 0x15 \
munge offset -10 u16 set 0x1515 \
pipe
to:
sudo tc filter add dev $ETH parent 1: protocol ip prio 10 \
u32 match ip protocol 1 0xff flowid 1:2 \
action skbmod dmac 02:15:15:15:15:15
Or worse, try to debug a policy with destination mac, source mac and
etherype. Then make that a hundred rules and you'll get my point.
The most important ethernet use case at the moment is when redirecting or
mirroring packets to a remote machine. The dst mac address needs a re-write
so that it doesnt get dropped or confuse an interconnecting (learning) switch
or dropped by a target machine (which looks at the dst mac).
In the future common use cases on pedit can be migrated to this action
(as an example different fields in ip v4/6, transports like tcp/udp/sctp
etc). For this first cut, this allows modifying basic ethernet header.
Signed-off-by: Jamal Hadi Salim <jhs@...atatu.com>
---
tc/Makefile | 1 +
tc/m_skbmod.c | 270 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 271 insertions(+)
create mode 100644 tc/m_skbmod.c
diff --git a/tc/Makefile b/tc/Makefile
index 8917eaf..e2f340c 100644
--- a/tc/Makefile
+++ b/tc/Makefile
@@ -45,6 +45,7 @@ TCMODULES += m_nat.o
TCMODULES += m_pedit.o
TCMODULES += m_ife.o
TCMODULES += m_skbedit.o
+TCMODULES += m_skbmod.o
TCMODULES += m_csum.o
TCMODULES += m_simple.o
TCMODULES += m_vlan.o
diff --git a/tc/m_skbmod.c b/tc/m_skbmod.c
new file mode 100644
index 0000000..38c83a2
--- /dev/null
+++ b/tc/m_skbmod.c
@@ -0,0 +1,270 @@
+/*
+ * m_skbmod.c skb modifier action module
+ *
+ * This program is free software; you can distribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * Authors: J Hadi Salim (jhs@...atatu.com)
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <syslog.h>
+#include <fcntl.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <string.h>
+#include <linux/netdevice.h>
+
+#include "rt_names.h"
+#include "utils.h"
+#include "tc_util.h"
+#include <linux/tc_act/tc_skbmod.h>
+
+static void skbmod_explain(void)
+{
+ fprintf(stderr,
+ "Usage:... skbmod {[set <SETTABLE>] [swap <SWAPABLE>]} [CONTROL] [index INDEX]\n");
+ fprintf(stderr, "where SETTABLE is: [dmac DMAC] [smac SMAC] [etype ETYPE] \n");
+ fprintf(stderr, "where SWAPABLE is: \"mac\" to swap mac addresses\n");
+ fprintf(stderr, "note: \"swap mac\" is done after any outstanding D/SMAC change\n");
+ fprintf(stderr,
+ "\tDMAC := 6 byte Destination MAC address\n"
+ "\tSMAC := optional 6 byte Source MAC address\n"
+ "\tETYPE := optional 16 bit ethertype\n"
+ "\tCONTROL := reclassify|pipe|drop|continue|ok\n"
+ "\tINDEX := skbmod index value to use\n");
+}
+
+static void skbmod_usage(void)
+{
+ skbmod_explain();
+ exit(-1);
+}
+
+static int parse_skbmod(struct action_util *a, int *argc_p, char ***argv_p,
+ int tca_id, struct nlmsghdr *n)
+{
+ int argc = *argc_p;
+ char **argv = *argv_p;
+ int ok = 0;
+ struct tc_skbmod p;
+ struct rtattr *tail;
+ char dbuf[ETH_ALEN];
+ char sbuf[ETH_ALEN];
+ __u16 skbmod_etype = 0;
+ char *daddr = NULL;
+ char *saddr = NULL;
+
+ memset(&p, 0, sizeof(p));
+ p.action = TC_ACT_PIPE; /* good default */
+
+ if (argc <= 0)
+ return -1;
+
+ while (argc > 0) {
+ if (matches(*argv, "skbmod") == 0) {
+ NEXT_ARG();
+ continue;
+ } else if (matches(*argv, "swap") == 0) {
+ NEXT_ARG();
+ continue;
+ } else if (matches(*argv, "mac") == 0) {
+ p.flags |= SKBMOD_F_SWAPMAC;
+ ok +=1;
+ } else if (matches(*argv, "set") == 0) {
+ NEXT_ARG();
+ continue;
+ } else if (matches(*argv, "etype") == 0) {
+ NEXT_ARG();
+ if (get_u16(&skbmod_etype, *argv, 0))
+ invarg("ethertype is invalid", *argv);
+ fprintf(stderr, "skbmod etype 0x%x\n", skbmod_etype);
+ p.flags |= SKBMOD_F_ETYPE;
+ ok +=1;
+ } else if (matches(*argv, "dmac") == 0) {
+ NEXT_ARG();
+ daddr = *argv;
+ if (sscanf(daddr, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
+ dbuf, dbuf + 1, dbuf + 2,
+ dbuf + 3, dbuf + 4, dbuf + 5) != 6) {
+ fprintf(stderr, "Invalid dst mac address %s\n",
+ daddr);
+ return -1;
+ }
+ p.flags |= SKBMOD_F_DMAC;
+ fprintf(stderr, "dst MAC address <%s>\n", daddr);
+ ok +=1;
+
+ } else if (matches(*argv, "smac") == 0) {
+ NEXT_ARG();
+ saddr = *argv;
+ if (sscanf(saddr, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
+ sbuf, sbuf + 1, sbuf + 2,
+ sbuf + 3, sbuf + 4, sbuf + 5) != 6) {
+ fprintf(stderr, "Invalid smac address %s\n",
+ saddr);
+ return -1;
+ }
+ p.flags |= SKBMOD_F_SMAC;
+ fprintf(stderr, "src MAC address <%s>\n", saddr);
+ ok +=1;
+ } else if (matches(*argv, "help") == 0) {
+ skbmod_usage();
+ } else {
+ break;
+ }
+
+ argc--;
+ argv++;
+ }
+
+#if 0
+ if (p.flags & SKBMOD_F_SWAPMAC) {
+ if ((p.flags & SKBMOD_F_DMAC) || (p.flags & SKBMOD_F_SMAC)) {
+ fprintf(stderr, "Not allowed to mix S/MAC and swapping\n");
+ skbmod_usage();
+ }
+ }
+#endif
+
+ if (argc) {
+ if (matches(*argv, "reclassify") == 0) {
+ p.action = TC_ACT_RECLASSIFY;
+ argc--;
+ argv++;
+ } else if (matches(*argv, "pipe") == 0) {
+ p.action = TC_ACT_PIPE;
+ argc--;
+ argv++;
+ } else if (matches(*argv, "drop") == 0 ||
+ matches(*argv, "shot") == 0) {
+ p.action = TC_ACT_SHOT;
+ argc--;
+ argv++;
+ } else if (matches(*argv, "continue") == 0) {
+ p.action = TC_ACT_UNSPEC;
+ argc--;
+ argv++;
+ } else if (matches(*argv, "pass") == 0 ||
+ matches(*argv, "ok") == 0) {
+ p.action = TC_ACT_OK;
+ argc--;
+ argv++;
+ }
+ }
+
+ if (argc) {
+ if (matches(*argv, "index") == 0) {
+ NEXT_ARG();
+ if (get_u32(&p.index, *argv, 0)) {
+ fprintf(stderr, "skbmod: Illegal \"index\"\n");
+ return -1;
+ }
+ ok++;
+ argc--;
+ argv++;
+ }
+ }
+
+ if (!ok) {
+ fprintf(stderr, "skbmod requires at least one option\n");
+ skbmod_usage();
+ }
+
+ tail = NLMSG_TAIL(n);
+ addattr_l(n, MAX_MSG, tca_id, NULL, 0);
+ addattr_l(n, MAX_MSG, TCA_SKBMOD_PARMS, &p, sizeof(p));
+
+ if (daddr)
+ addattr_l(n, MAX_MSG, TCA_SKBMOD_DMAC, dbuf, ETH_ALEN);
+ if (skbmod_etype)
+ addattr16(n, MAX_MSG, TCA_SKBMOD_ETYPE, skbmod_etype);
+ if (saddr)
+ addattr_l(n, MAX_MSG, TCA_SKBMOD_SMAC, sbuf, ETH_ALEN);
+
+ tail->rta_len = (void *)NLMSG_TAIL(n) - (void *)tail;
+
+ *argc_p = argc;
+ *argv_p = argv;
+ return 0;
+}
+
+static int print_skbmod(struct action_util *au, FILE *f, struct rtattr *arg)
+{
+ struct tc_skbmod *p = NULL;
+ struct rtattr *tb[TCA_SKBMOD_MAX + 1];
+ __u16 skbmod_etype = 0;
+ int has_optional = 0;
+ SPRINT_BUF(b1);
+ SPRINT_BUF(b2);
+
+ if (arg == NULL)
+ return -1;
+
+ parse_rtattr_nested(tb, TCA_SKBMOD_MAX, arg);
+
+ if (tb[TCA_SKBMOD_PARMS] == NULL) {
+ fprintf(f, "[NULL skbmod parameters]");
+ return -1;
+ }
+
+ p = RTA_DATA(tb[TCA_SKBMOD_PARMS]);
+
+ fprintf(f, "skbmod action %s ", action_n2a(p->action));
+
+ if (tb[TCA_SKBMOD_ETYPE]) {
+ skbmod_etype = rta_getattr_u16(tb[TCA_SKBMOD_ETYPE]);
+ has_optional = 1;
+ fprintf(f, "set etype 0x%X ", skbmod_etype);
+ }
+
+ if (has_optional)
+ fprintf(f, "\n\t ");
+
+ if (tb[TCA_SKBMOD_DMAC]) {
+ has_optional = 1;
+ fprintf(f, "set dmac %s ",
+ ll_addr_n2a(RTA_DATA(tb[TCA_SKBMOD_DMAC]),
+ RTA_PAYLOAD(tb[TCA_SKBMOD_DMAC]), 0, b1,
+ sizeof(b1)));
+
+ }
+
+ if (tb[TCA_SKBMOD_SMAC]) {
+ has_optional = 1;
+ fprintf(f, "set smac %s ",
+ ll_addr_n2a(RTA_DATA(tb[TCA_SKBMOD_SMAC]),
+ RTA_PAYLOAD(tb[TCA_SKBMOD_SMAC]), 0, b2,
+ sizeof(b2)));
+ }
+
+ if (p->flags & SKBMOD_F_SWAPMAC) {
+ fprintf(f, "swap mac ");
+ }
+
+ fprintf(f, "\n\t index %d ref %d bind %d", p->index, p->refcnt,
+ p->bindcnt);
+ if (show_stats) {
+ if (tb[TCA_SKBMOD_TM]) {
+ struct tcf_t *tm = RTA_DATA(tb[TCA_SKBMOD_TM]);
+
+ print_tm(f, tm);
+ }
+ }
+
+ fprintf(f, "\n");
+
+ return 0;
+}
+
+struct action_util skbmod_action_util = {
+ .id = "skbmod",
+ .parse_aopt = parse_skbmod,
+ .print_aopt = print_skbmod,
+};
--
1.9.1
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