xfrm: enable to manage default policies

Two new commands to manage default policies:
 - ip xfrm policy setdefault
 - ip xfrm policy getdefault

And the corresponding part in 'ip xfrm monitor'.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David Ahern <dsahern@kernel.org>

ip/xfrm.h

@@ -132,6 +132,7 @@ void xfrm_state_info_print(struct xfrm_usersa_info *xsinfo,
 void xfrm_policy_info_print(struct xfrm_userpolicy_info *xpinfo,
 			    struct rtattr *tb[], FILE *fp, const char *prefix,
 			    const char *title);
+int xfrm_policy_default_print(struct nlmsghdr *n, FILE *fp);
 int xfrm_id_parse(xfrm_address_t *saddr, struct xfrm_id *id, __u16 *family,
 		  int loose, int *argcp, char ***argvp);
 int xfrm_mode_parse(__u8 *mode, int *argcp, char ***argvp);

ip/xfrm_monitor.c

@@ -323,6 +323,9 @@ static int xfrm_accept_msg(struct rtnl_ctrl_data *ctrl,
 	case XFRM_MSG_MAPPING:
 		xfrm_mapping_print(n, arg);
 		return 0;
+	case XFRM_MSG_GETDEFAULT:
+		xfrm_policy_default_print(n, arg);
+		return 0;
 	default:
 		break;
 	}

ip/xfrm_policy.c

@@ -66,6 +66,8 @@ static void usage(void)
 		"Usage: ip xfrm policy flush [ ptype PTYPE ]\n"
 		"Usage: ip xfrm policy count\n"
 		"Usage: ip xfrm policy set [ hthresh4 LBITS RBITS ] [ hthresh6 LBITS RBITS ]\n"
+		"Usage: ip xfrm policy setdefault DIR ACTION [ DIR ACTION ] [ DIR ACTION ]\n"
+		"Usage: ip xfrm policy getdefault\n"
 		"SELECTOR := [ src ADDR[/PLEN] ] [ dst ADDR[/PLEN] ] [ dev DEV ] [ UPSPEC ]\n"
 		"UPSPEC := proto { { tcp | udp | sctp | dccp } [ sport PORT ] [ dport PORT ] |\n"
 		"                  { icmp | ipv6-icmp | mobility-header } [ type NUMBER ] [ code NUMBER ] |\n"
@@ -1124,6 +1126,133 @@ static int xfrm_spd_getinfo(int argc, char **argv)
 	return 0;
 }
 
+static int xfrm_str_to_policy(char *name, uint8_t *policy)
+{
+	if (strcmp(name, "block") == 0) {
+		*policy = XFRM_USERPOLICY_BLOCK;
+		return 0;
+	} else if (strcmp(name, "accept") == 0) {
+		*policy = XFRM_USERPOLICY_ACCEPT;
+		return 0;
+	}
+
+	return -1;
+}
+
+static char *xfrm_policy_to_str(uint8_t policy)
+{
+	switch (policy) {
+	case XFRM_USERPOLICY_UNSPEC:
+		return "unspec";
+	case XFRM_USERPOLICY_BLOCK:
+		return "block";
+	case XFRM_USERPOLICY_ACCEPT:
+		return "accept";
+	default:
+		return "unknown";
+	}
+}
+
+static int xfrm_spd_setdefault(int argc, char **argv)
+{
+	struct rtnl_handle rth;
+	struct {
+		struct nlmsghdr			n;
+		struct xfrm_userpolicy_default  up;
+	} req = {
+		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct xfrm_userpolicy_default)),
+		.n.nlmsg_flags = NLM_F_REQUEST,
+		.n.nlmsg_type = XFRM_MSG_SETDEFAULT,
+	};
+
+	while (argc > 0) {
+		if (strcmp(*argv, "in") == 0) {
+			if (req.up.in)
+				duparg("in", *argv);
+
+			NEXT_ARG();
+			if (xfrm_str_to_policy(*argv, &req.up.in) < 0)
+				invarg("in policy value is invalid", *argv);
+		} else if (strcmp(*argv, "fwd") == 0) {
+			if (req.up.fwd)
+				duparg("fwd", *argv);
+
+			NEXT_ARG();
+			if (xfrm_str_to_policy(*argv, &req.up.fwd) < 0)
+				invarg("fwd policy value is invalid", *argv);
+		} else if (strcmp(*argv, "out") == 0) {
+			if (req.up.out)
+				duparg("out", *argv);
+
+			NEXT_ARG();
+			if (xfrm_str_to_policy(*argv, &req.up.out) < 0)
+				invarg("out policy value is invalid", *argv);
+		} else {
+			invarg("unknown direction", *argv);
+		}
+
+		argc--; argv++;
+	}
+
+	if (rtnl_open_byproto(&rth, 0, NETLINK_XFRM) < 0)
+		exit(1);
+
+	if (rtnl_talk(&rth, &req.n, NULL) < 0)
+		exit(2);
+
+	rtnl_close(&rth);
+
+	return 0;
+}
+
+int xfrm_policy_default_print(struct nlmsghdr *n, FILE *fp)
+{
+	struct xfrm_userpolicy_default *up = NLMSG_DATA(n);
+	int len = n->nlmsg_len - NLMSG_SPACE(sizeof(*up));
+
+	if (len < 0) {
+		fprintf(stderr,
+			"BUG: short nlmsg len %u (expect %lu) for XFRM_MSG_GETDEFAULT\n",
+			n->nlmsg_len, NLMSG_SPACE(sizeof(*up)));
+		return -1;
+	}
+
+	fprintf(fp, "Default policies:\n");
+	fprintf(fp, " in:  %s\n", xfrm_policy_to_str(up->in));
+	fprintf(fp, " fwd: %s\n", xfrm_policy_to_str(up->fwd));
+	fprintf(fp, " out: %s\n", xfrm_policy_to_str(up->out));
+	fflush(fp);
+
+	return 0;
+}
+
+static int xfrm_spd_getdefault(int argc, char **argv)
+{
+	struct rtnl_handle rth;
+	struct {
+		struct nlmsghdr			n;
+		struct xfrm_userpolicy_default  up;
+	} req = {
+		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct xfrm_userpolicy_default)),
+		.n.nlmsg_flags = NLM_F_REQUEST,
+		.n.nlmsg_type = XFRM_MSG_GETDEFAULT,
+	};
+	struct nlmsghdr *answer;
+
+	if (rtnl_open_byproto(&rth, 0, NETLINK_XFRM) < 0)
+		exit(1);
+
+	if (rtnl_talk(&rth, &req.n, &answer) < 0)
+		exit(2);
+
+	xfrm_policy_default_print(answer, (FILE *)stdout);
+
+	free(answer);
+	rtnl_close(&rth);
+
+	return 0;
+}
+
 static int xfrm_policy_flush(int argc, char **argv)
 {
 	struct rtnl_handle rth;
@@ -1197,6 +1326,10 @@ int do_xfrm_policy(int argc, char **argv)
 		return xfrm_spd_getinfo(argc, argv);
 	if (matches(*argv, "set") == 0)
 		return xfrm_spd_setinfo(argc-1, argv+1);
+	if (matches(*argv, "setdefault") == 0)
+		return xfrm_spd_setdefault(argc-1, argv+1);
+	if (matches(*argv, "getdefault") == 0)
+		return xfrm_spd_getdefault(argc-1, argv+1);
 	if (matches(*argv, "help") == 0)
 		usage();
 	fprintf(stderr, "Command \"%s\" is unknown, try \"ip xfrm policy help\".\n", *argv);

man/man8/ip-xfrm.8

@@ -298,6 +298,18 @@ ip-xfrm \- transform configuration
 .RB "[ " hthresh6
 .IR LBITS " " RBITS " ]"
 
+.ti -8
+.B "ip xfrm policy setdefault"
+.IR DIR
+.IR ACTION " [ "
+.IR DIR
+.IR ACTION " ] [ "
+.IR DIR
+.IR ACTION " ]"
+
+.ti -8
+.B "ip xfrm policy getdefault"
+
 .ti -8
 .IR SELECTOR " :="
 .RB "[ " src