git: a03aff88a144 - main - icmp6: bring rate limiting on a par with IPv4
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Date: Sun, 24 Mar 2024 16:19:34 UTC
The branch main has been updated by glebius:
URL: https://cgit.FreeBSD.org/src/commit/?id=a03aff88a14448c3084a0384082ec996d7213897
commit a03aff88a14448c3084a0384082ec996d7213897
Author: Gleb Smirnoff <glebius@FreeBSD.org>
AuthorDate: 2024-03-24 16:13:23 +0000
Commit: Gleb Smirnoff <glebius@FreeBSD.org>
CommitDate: 2024-03-24 16:13:23 +0000
icmp6: bring rate limiting on a par with IPv4
Use counter_ratecheck() instead of racy and slow ppsratecheck. Use a
separate counter for every currently known type of ICMPv6. Provide logging
of ratelimit events. Provide jitter to counter open UDP port detection.
Reviewed by: tuexen, zlei
Differential Revision: https://reviews.freebsd.org/D44482
---
sys/netinet6/icmp6.c | 185 ++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 162 insertions(+), 23 deletions(-)
diff --git a/sys/netinet6/icmp6.c b/sys/netinet6/icmp6.c
index 8f039d6dd196..ef4216b844b5 100644
--- a/sys/netinet6/icmp6.c
+++ b/sys/netinet6/icmp6.c
@@ -143,18 +143,6 @@ SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_NODEINFO, nodeinfo,
VNET_DECLARE(struct inpcbinfo, ripcbinfo);
#define V_ripcbinfo VNET(ripcbinfo)
-VNET_DEFINE_STATIC(int, icmp6errppslim) = 100;
-#define V_icmp6errppslim VNET(icmp6errppslim)
-SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_ERRPPSLIMIT, errppslimit,
- CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmp6errppslim), 0,
- "Maximum number of ICMPv6 error messages per second");
-
-VNET_DEFINE_STATIC(int, icmp6errpps_count) = 0;
-VNET_DEFINE_STATIC(struct timeval, icmp6errppslim_last);
-
-#define V_icmp6errpps_count VNET(icmp6errpps_count)
-#define V_icmp6errppslim_last VNET(icmp6errppslim_last)
-
static void icmp6_errcount(int, int);
static int icmp6_rip6_input(struct mbuf **, int);
static void icmp6_reflect(struct mbuf *, size_t);
@@ -2743,6 +2731,126 @@ icmp6_ctloutput(struct socket *so, struct sockopt *sopt)
return (error);
}
+static int sysctl_icmp6lim_and_jitter(SYSCTL_HANDLER_ARGS);
+VNET_DEFINE_STATIC(u_int, icmp6errppslim) = 100;
+#define V_icmp6errppslim VNET(icmp6errppslim)
+SYSCTL_PROC(_net_inet6_icmp6, ICMPV6CTL_ERRPPSLIMIT, errppslimit,
+ CTLTYPE_UINT | CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmp6errppslim), 0,
+ &sysctl_icmp6lim_and_jitter, "IU",
+ "Maximum number of ICMPv6 error/reply messages per second");
+
+VNET_DEFINE_STATIC(int, icmp6lim_curr_jitter) = 0;
+#define V_icmp6lim_curr_jitter VNET(icmp6lim_curr_jitter)
+
+VNET_DEFINE_STATIC(u_int, icmp6lim_jitter) = 8;
+#define V_icmp6lim_jitter VNET(icmp6lim_jitter)
+SYSCTL_PROC(_net_inet6_icmp6, OID_AUTO, icmp6lim_jitter, CTLTYPE_UINT |
+ CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmp6lim_jitter), 0,
+ &sysctl_icmp6lim_and_jitter, "IU",
+ "Random errppslimit jitter adjustment limit");
+
+VNET_DEFINE_STATIC(int, icmp6lim_output) = 1;
+#define V_icmp6lim_output VNET(icmp6lim_output)
+SYSCTL_INT(_net_inet6_icmp6, OID_AUTO, icmp6lim_output,
+ CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmp6lim_output), 0,
+ "Enable logging of ICMPv6 response rate limiting");
+
+typedef enum {
+ RATELIM_PARAM_PROB = 0,
+ RATELIM_TOO_BIG,
+ RATELIM_UNREACH,
+ RATELIM_TEXCEED,
+ RATELIM_REDIR,
+ RATELIM_REPLY,
+ RATELIM_OTHER,
+ RATELIM_MAX
+} ratelim_which;
+
+static const char *icmp6_rate_descrs[RATELIM_MAX] = {
+ [RATELIM_PARAM_PROB] = "bad IPv6 header",
+ [RATELIM_TOO_BIG] = "packet too big",
+ [RATELIM_UNREACH] = "destination unreachable",
+ [RATELIM_TEXCEED] = "time exceeded",
+ [RATELIM_REPLY] = "echo reply",
+ [RATELIM_REDIR] = "neighbor discovery redirect",
+ [RATELIM_OTHER] = "(other)",
+};
+
+static void
+icmp6lim_new_jitter(void)
+{
+ /*
+ * Adjust limit +/- to jitter the measurement to deny a side-channel
+ * port scan as in https://dl.acm.org/doi/10.1145/3372297.3417280
+ */
+ if (V_icmp6lim_jitter > 0)
+ V_icmp6lim_curr_jitter =
+ arc4random_uniform(V_icmp6lim_jitter * 2 + 1) -
+ V_icmp6lim_jitter;
+}
+
+static int
+sysctl_icmp6lim_and_jitter(SYSCTL_HANDLER_ARGS)
+{
+ uint32_t new;
+ int error;
+ bool lim;
+
+ MPASS(oidp->oid_arg1 == &VNET_NAME(icmp6errppslim) ||
+ oidp->oid_arg1 == &VNET_NAME(icmp6lim_jitter));
+
+ lim = (oidp->oid_arg1 == &VNET_NAME(icmp6errppslim));
+ new = lim ? V_icmp6errppslim : V_icmp6lim_jitter;
+ error = sysctl_handle_int(oidp, &new, 0, req);
+ if (error == 0 && req->newptr) {
+ if (lim) {
+ if (new <= V_icmp6lim_jitter)
+ error = EINVAL;
+ else
+ V_icmp6errppslim = new;
+ } else {
+ if (new >= V_icmp6errppslim)
+ error = EINVAL;
+ else {
+ V_icmp6lim_jitter = new;
+ icmp6lim_new_jitter();
+ }
+ }
+ }
+ MPASS(V_icmp6errppslim + V_icmp6lim_curr_jitter > 0);
+
+ return (error);
+}
+
+
+VNET_DEFINE_STATIC(struct counter_rate, icmp6_rates[RATELIM_MAX]);
+#define V_icmp6_rates VNET(icmp6_rates)
+
+static void
+icmp6_ratelimit_init(void)
+{
+
+ for (int i = 0; i < RATELIM_MAX; i++) {
+ V_icmp6_rates[i].cr_rate = counter_u64_alloc(M_WAITOK);
+ V_icmp6_rates[i].cr_ticks = ticks;
+ }
+ icmp6lim_new_jitter();
+}
+VNET_SYSINIT(icmp6_ratelimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY,
+ icmp6_ratelimit_init, NULL);
+
+#ifdef VIMAGE
+static void
+icmp6_ratelimit_uninit(void)
+{
+
+ for (int i = 0; i < RATELIM_MAX; i++)
+ counter_u64_free(V_icmp6_rates[i].cr_rate);
+}
+VNET_SYSUNINIT(icmp6_ratelimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD,
+ icmp6_ratelimit_uninit, NULL);
+#endif
+
/*
* Perform rate limit check.
* Returns 0 if it is okay to send the icmp6 packet.
@@ -2752,24 +2860,55 @@ icmp6_ctloutput(struct socket *so, struct sockopt *sopt)
* XXX per-destination/type check necessary?
*
* dst - not used at this moment
- * type - not used at this moment
* code - not used at this moment
*/
int
-icmp6_ratelimit(const struct in6_addr *dst, const int type,
- const int code)
+icmp6_ratelimit(const struct in6_addr *dst, const int type, const int code)
{
- int ret;
+ ratelim_which which;
+ int64_t pps;
- ret = 0; /* okay to send */
+ if (V_icmp6errppslim == 0)
+ return (0);
- /* PPS limit */
- if (!ppsratecheck(&V_icmp6errppslim_last, &V_icmp6errpps_count,
- V_icmp6errppslim)) {
- /* The packet is subject to rate limit */
- ret++;
+ switch (type) {
+ case ICMP6_PARAM_PROB:
+ which = RATELIM_PARAM_PROB;
+ break;
+ case ICMP6_PACKET_TOO_BIG:
+ which = RATELIM_TOO_BIG;
+ break;
+ case ICMP6_DST_UNREACH:
+ which = RATELIM_UNREACH;
+ break;
+ case ICMP6_TIME_EXCEEDED:
+ which = RATELIM_TEXCEED;
+ break;
+ case ND_REDIRECT:
+ which = RATELIM_REDIR;
+ break;
+ case ICMP6_ECHO_REPLY:
+ which = RATELIM_REPLY;
+ break;
+ default:
+ which = RATELIM_OTHER;
+ break;
+ };
+
+ pps = counter_ratecheck(&V_icmp6_rates[which], V_icmp6errppslim +
+ V_icmp6lim_curr_jitter);
+ if (pps > 0) {
+ if (V_icmp6lim_output)
+ log(LOG_NOTICE, "Limiting ICMPv6 %s output from %jd "
+ "to %d packets/sec\n", icmp6_rate_descrs[which],
+ (intmax_t )pps, V_icmp6errppslim +
+ V_icmp6lim_curr_jitter);
+ icmp6lim_new_jitter();
+ }
+ if (pps == -1) {
ICMP6STAT_INC(icp6s_toofreq);
+ return (-1);
}
- return ret;
+ return (0);
}