netdev - [PATCH iproute2 1/1] actions: Add support for user cookies

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Date:   Sat, 22 Apr 2017 08:36:23 -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 1/1] actions: Add support for user cookies

From: Jamal Hadi Salim <jhs@...atatu.com>

Make use of 128b user cookies

Introduce optional 128-bit action cookie.
Like all other cookie schemes in the networking world (eg in protocols
like http or existing kernel fib protocol field, etc) the idea is to
save user state that when retrieved serves as a correlator. The kernel
_should not_ intepret it. The user can store whatever they wish in the
128 bits.

Sample exercise(showing variable length use of cookie)

.. create an accept action with cookie a1b2c3d4
sudo $TC actions add action ok index 1 cookie a1b2c3d4

.. dump all gact actions..
sudo $TC -s actions ls action gact

    action order 0: gact action pass
     random type none pass val 0
     index 1 ref 1 bind 0 installed 5 sec used 5 sec
    Action statistics:
    Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
    backlog 0b 0p requeues 0
    cookie a1b2c3d4

.. bind the accept action to a filter..
sudo $TC filter add dev lo parent ffff: protocol ip prio 1 \
u32 match ip dst 127.0.0.1/32 flowid 1:1 action gact index 1

... send some traffic..
$ ping 127.0.0.1 -c 3
PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.020 ms
64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.027 ms
64 bytes from 127.0.0.1: icmp_seq=3 ttl=64 time=0.038 ms

Signed-off-by: Jamal Hadi Salim <jhs@...atatu.com>
---
 tc/m_action.c | 49 +++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 43 insertions(+), 6 deletions(-)

diff --git a/tc/m_action.c b/tc/m_action.c
index 05ef07e..6ebe85e 100644
--- a/tc/m_action.c
+++ b/tc/m_action.c
@@ -150,18 +150,19 @@ new_cmd(char **argv)
 
 }
 
-int
-parse_action(int *argc_p, char ***argv_p, int tca_id, struct nlmsghdr *n)
+int parse_action(int *argc_p, char ***argv_p, int tca_id, struct nlmsghdr *n)
 {
 	int argc = *argc_p;
 	char **argv = *argv_p;
 	struct rtattr *tail, *tail2;
 	char k[16];
+	int act_ck_len = 0;
 	int ok = 0;
 	int eap = 0; /* expect action parameters */
 
 	int ret = 0;
 	int prio = 0;
+	unsigned char act_ck[TC_COOKIE_MAX_SIZE];
 
 	if (argc <= 0)
 		return -1;
@@ -215,16 +216,44 @@ done0:
 			addattr_l(n, MAX_MSG, ++prio, NULL, 0);
 			addattr_l(n, MAX_MSG, TCA_ACT_KIND, k, strlen(k) + 1);
 
-			ret = a->parse_aopt(a, &argc, &argv, TCA_ACT_OPTIONS, n);
+			ret = a->parse_aopt(a, &argc, &argv, TCA_ACT_OPTIONS,
+					    n);
 
 			if (ret < 0) {
 				fprintf(stderr, "bad action parsing\n");
 				goto bad_val;
 			}
+
+			if (*argv && strcmp(*argv, "cookie") == 0) {
+				size_t slen;
+
+				NEXT_ARG();
+				slen = strlen(*argv);
+				if (slen > TC_COOKIE_MAX_SIZE * 2) {
+					char cookie_err_m[128];
+
+					snprintf(cookie_err_m, 128,
+						 "%zd Max allowed size %d",
+						 slen, TC_COOKIE_MAX_SIZE*2);
+					invarg(cookie_err_m, *argv);
+				}
+
+				if (hex2mem(*argv, act_ck, slen / 2) < 0)
+					invarg("cookie must be a hex string\n",
+					       *argv);
+
+				act_ck_len = slen;
+				argc--;
+				argv++;
+			}
+
+			if (act_ck_len)
+				addattr_l(n, MAX_MSG, TCA_ACT_COOKIE,
+					  &act_ck, act_ck_len);
+
 			tail->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail;
 			ok++;
 		}
-
 	}
 
 	if (eap > 0) {
@@ -245,8 +274,7 @@ bad_val:
 	return -1;
 }
 
-static int
-tc_print_one_action(FILE *f, struct rtattr *arg)
+static int tc_print_one_action(FILE *f, struct rtattr *arg)
 {
 
 	struct rtattr *tb[TCA_ACT_MAX + 1];
@@ -274,8 +302,17 @@ tc_print_one_action(FILE *f, struct rtattr *arg)
 		return err;
 
 	if (show_stats && tb[TCA_ACT_STATS]) {
+
 		fprintf(f, "\tAction statistics:\n");
 		print_tcstats2_attr(f, tb[TCA_ACT_STATS], "\t", NULL);
+		if (tb[TCA_ACT_COOKIE]) {
+			int strsz = RTA_PAYLOAD(tb[TCA_ACT_COOKIE]);
+			char b1[strsz+1];
+
+			fprintf(f, "\n\tcookie len %d %s ", strsz,
+				hexstring_n2a(RTA_DATA(tb[TCA_ACT_COOKIE]),
+					      strsz, b1, sizeof(b1)));
+		}
 		fprintf(f, "\n");
 	}
 
-- 
1.9.1