From: Dmitry Safonov <dima@arista.com>
To: Eric Dumazet <edumazet@google.com>,
"David S. Miller" <davem@davemloft.net>,
linux-kernel@vger.kernel.org
Cc: Dmitry Safonov <dima@arista.com>,
Andy Lutomirski <luto@amacapital.net>,
Ard Biesheuvel <ardb@kernel.org>,
Bob Gilligan <gilligan@arista.com>,
David Ahern <dsahern@kernel.org>,
Dmitry Safonov <0x7f454c46@gmail.com>,
Eric Biggers <ebiggers@kernel.org>,
Francesco Ruggeri <fruggeri@arista.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
Ivan Delalande <colona@arista.com>,
Jakub Kicinski <kuba@kernel.org>,
Leonard Crestez <cdleonard@gmail.com>,
Paolo Abeni <pabeni@redhat.com>,
Salam Noureddine <noureddine@arista.com>,
Shuah Khan <shuah@kernel.org>,
netdev@vger.kernel.org, linux-crypto@vger.kernel.org
Subject: [PATCH 21/31] net/tcp: Ignore specific ICMPs for TCP-AO connections
Date: Thu, 18 Aug 2022 17:59:55 +0100 [thread overview]
Message-ID: <20220818170005.747015-22-dima@arista.com> (raw)
In-Reply-To: <20220818170005.747015-1-dima@arista.com>
Similarly to IPsec, RFC5925 prescribes:
">> A TCP-AO implementation MUST default to ignore incoming ICMPv4
messages of Type 3 (destination unreachable), Codes 2-4 (protocol
unreachable, port unreachable, and fragmentation needed -- ’hard
errors’), and ICMPv6 Type 1 (destination unreachable), Code 1
(administratively prohibited) and Code 4 (port unreachable) intended
for connections in synchronized states (ESTABLISHED, FIN-WAIT-1, FIN-
WAIT-2, CLOSE-WAIT, CLOSING, LAST-ACK, TIME-WAIT) that match MKTs."
A selftest (later in patch series) verifies that this attack is not
possible in this TCP-AO implementation.
Co-developed-by: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Co-developed-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
include/net/tcp_ao.h | 9 +++++
include/uapi/linux/snmp.h | 1 +
include/uapi/linux/tcp.h | 1 +
net/ipv4/proc.c | 1 +
net/ipv4/tcp_ao.c | 70 ++++++++++++++++++++++++++++++++++++++-
net/ipv4/tcp_ipv4.c | 5 +++
net/ipv6/tcp_ipv6.c | 4 +++
7 files changed, 90 insertions(+), 1 deletion(-)
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index e99c8f300a5a..743a910ba508 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -25,6 +25,7 @@ struct tcp_ao_counters {
atomic64_t pkt_bad;
atomic64_t key_not_found;
atomic64_t ao_required;
+ atomic64_t dropped_icmp;
};
struct tcp_ao_key {
@@ -77,6 +78,9 @@ static inline unsigned int tcp_ao_digest_size(struct tcp_ao_key *key)
return key->digest_size;
}
+/* bits in 'ao_flags' */
+#define AO_ACCEPT_ICMPS BIT(0)
+
struct tcp_ao_info {
struct hlist_head head;
struct rcu_head rcu;
@@ -169,6 +173,7 @@ u32 tcp_ao_compute_sne(u32 sne, u32 seq, u32 new_seq);
void tcp_ao_time_wait(struct tcp_timewait_sock *tcptw, struct tcp_sock *tp);
int tcp_ao_cache_traffic_keys(const struct sock *sk, struct tcp_ao_info *ao,
struct tcp_ao_key *ao_key);
+bool tcp_ao_ignore_icmp(struct sock *sk, int type, int code);
enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk,
const struct sk_buff *skb, unsigned short int family,
const struct request_sock *req,
@@ -239,6 +244,10 @@ void tcp_ao_connect_init(struct sock *sk);
#else /* CONFIG_TCP_AO */
+static inline bool tcp_ao_ignore_icmp(struct sock *sk, int type, int code)
+{
+ return false;
+}
static inline enum skb_drop_reason tcp_inbound_ao_hash(struct sock *sk,
const struct sk_buff *skb, unsigned short int family,
const struct request_sock *req, const struct tcp_ao_hdr *aoh)
diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index f09119db8b40..bc7655394e9a 100644
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -296,6 +296,7 @@ enum
LINUX_MIB_TCPAOBAD, /* TCPAOBad */
LINUX_MIB_TCPAOKEYNOTFOUND, /* TCPAOKeyNotFound */
LINUX_MIB_TCPAOGOOD, /* TCPAOGood */
+ LINUX_MIB_TCPAODROPPEDICMPS, /* TCPAODroppedIcmps */
__LINUX_MIB_MAX
};
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 5369458ae89f..508bedbc6ad8 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -349,6 +349,7 @@ struct tcp_diag_md5sig {
#define TCP_AO_CMDF_CURR (1 << 0) /* Only checks field sndid */
#define TCP_AO_CMDF_NEXT (1 << 1) /* Only checks field rcvid */
+#define TCP_AO_CMDF_ACCEPT_ICMP (1 << 2) /* Accept incoming ICMPs */
struct tcp_ao { /* setsockopt(TCP_AO) */
struct __kernel_sockaddr_storage tcpa_addr;
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 1b5a078adcf1..ccfb7f51e82f 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -301,6 +301,7 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("TCPAOBad", LINUX_MIB_TCPAOBAD),
SNMP_MIB_ITEM("TCPAOKeyNotFound", LINUX_MIB_TCPAOKEYNOTFOUND),
SNMP_MIB_ITEM("TCPAOGood", LINUX_MIB_TCPAOGOOD),
+ SNMP_MIB_ITEM("TCPAODroppedIcmps", LINUX_MIB_TCPAODROPPEDICMPS),
SNMP_MIB_SENTINEL
};
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 4283e0193e2a..858295393643 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -15,6 +15,7 @@
#include <net/tcp.h>
#include <net/ipv6.h>
+#include <net/icmp.h>
int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
unsigned int len)
@@ -52,6 +53,63 @@ int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,
return 1;
}
+bool tcp_ao_ignore_icmp(struct sock *sk, int type, int code)
+{
+ struct tcp_ao_info *ao;
+ bool ignore_icmp = false;
+
+ /* RFC5925, 7.8:
+ * >> A TCP-AO implementation MUST default to ignore incoming ICMPv4
+ * messages of Type 3 (destination unreachable), Codes 2-4 (protocol
+ * unreachable, port unreachable, and fragmentation needed -- ’hard
+ * errors’), and ICMPv6 Type 1 (destination unreachable), Code 1
+ * (administratively prohibited) and Code 4 (port unreachable) intended
+ * for connections in synchronized states (ESTABLISHED, FIN-WAIT-1, FIN-
+ * WAIT-2, CLOSE-WAIT, CLOSING, LAST-ACK, TIME-WAIT) that match MKTs.
+ */
+ if (sk->sk_family == AF_INET) {
+ if (type != ICMP_DEST_UNREACH)
+ return false;
+ if (code < ICMP_PROT_UNREACH || code > ICMP_FRAG_NEEDED)
+ return false;
+ } else if (sk->sk_family == AF_INET6) {
+ if (type != ICMPV6_DEST_UNREACH)
+ return false;
+ if (code != ICMPV6_ADM_PROHIBITED && code != ICMPV6_PORT_UNREACH)
+ return false;
+ } else {
+ WARN_ON_ONCE(1);
+ return false;
+ }
+
+ rcu_read_lock();
+ switch (sk->sk_state) {
+ case TCP_TIME_WAIT:
+ ao = rcu_dereference(tcp_twsk(sk)->ao_info);
+ break;
+ case TCP_SYN_SENT:
+ case TCP_SYN_RECV:
+ case TCP_LISTEN:
+ case TCP_NEW_SYN_RECV:
+ /* RFC5925 specifies to ignore ICMPs *only* on connections
+ * in synchronized states.
+ */
+ rcu_read_unlock();
+ return false;
+ default:
+ ao = rcu_dereference(tcp_sk(sk)->ao_info);
+ }
+
+ if (ao && !(ao->ao_flags & AO_ACCEPT_ICMPS)) {
+ ignore_icmp = true;
+ __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAODROPPEDICMPS);
+ atomic64_inc(&ao->counters.dropped_icmp);
+ }
+ rcu_read_unlock();
+
+ return ignore_icmp;
+}
+
struct tcp_ao_key *tcp_ao_do_lookup_keyid(struct tcp_ao_info *ao,
int sndid, int rcvid)
{
@@ -1360,7 +1418,7 @@ static bool tcp_ao_mkt_overlap_v6(struct tcp_ao *cmd,
#define TCP_AO_KEYF_ALL (0)
#define TCP_AO_CMDF_ADDMOD_VALID \
- (TCP_AO_CMDF_CURR | TCP_AO_CMDF_NEXT)
+ (TCP_AO_CMDF_CURR | TCP_AO_CMDF_NEXT | TCP_AO_CMDF_ACCEPT_ICMP)
#define TCP_AO_CMDF_DEL_VALID \
(TCP_AO_CMDF_CURR | TCP_AO_CMDF_NEXT)
@@ -1443,6 +1501,11 @@ static int tcp_ao_add_cmd(struct sock *sk, unsigned short int family,
atomic64_set(&key->pkt_good, 0);
atomic64_set(&key->pkt_bad, 0);
+ if (cmd.tcpa_flags & TCP_AO_CMDF_ACCEPT_ICMP)
+ ao_info->ao_flags |= AO_ACCEPT_ICMPS;
+ else
+ ao_info->ao_flags &= ~AO_ACCEPT_ICMPS;
+
ret = tcp_ao_parse_crypto(&cmd, key);
if (ret < 0)
goto err_free_sock;
@@ -1601,6 +1664,11 @@ static int tcp_ao_mod_cmd(struct sock *sk, unsigned short int family,
if (!ao_info)
return -ENOENT;
/* TODO: make tcp_ao_current_rnext() and flags set atomic */
+ if (cmd.tcpa_flags & TCP_AO_CMDF_ACCEPT_ICMP)
+ ao_info->ao_flags |= AO_ACCEPT_ICMPS;
+ else
+ ao_info->ao_flags &= ~AO_ACCEPT_ICMPS;
+
return tcp_ao_current_rnext(sk, cmd.tcpa_flags,
cmd.tcpa_current, cmd.tcpa_rnext);
}
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index a1e1a23abfea..bb4d208da8a8 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -484,6 +484,8 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
return -ENOENT;
}
if (sk->sk_state == TCP_TIME_WAIT) {
+ /* To increase the counter of ignored icmps for TCP-AO */
+ tcp_ao_ignore_icmp(sk, type, code);
inet_twsk_put(inet_twsk(sk));
return 0;
}
@@ -498,6 +500,9 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
}
bh_lock_sock(sk);
+ if (tcp_ao_ignore_icmp(sk, type, code))
+ goto out;
+
/* If too many ICMPs get dropped on busy
* servers this needs to be solved differently.
* We do take care of PMTU discovery (RFC1191) special case :
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 8a27408549cd..78994d1cbc45 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -399,6 +399,8 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
}
if (sk->sk_state == TCP_TIME_WAIT) {
+ /* To increase the counter of ignored icmps for TCP-AO */
+ tcp_ao_ignore_icmp(sk, type, code);
inet_twsk_put(inet_twsk(sk));
return 0;
}
@@ -410,6 +412,8 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
}
bh_lock_sock(sk);
+ if (tcp_ao_ignore_icmp(sk, type, code))
+ goto out;
if (sock_owned_by_user(sk) && type != ICMPV6_PKT_TOOBIG)
__NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
--
2.37.2
next prev parent reply other threads:[~2022-08-18 17:04 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-18 16:59 [PATCH 00/31] net/tcp: Add TCP-AO support Dmitry Safonov
2022-08-18 16:59 ` [PATCH 01/31] crypto: Introduce crypto_pool Dmitry Safonov
2022-08-18 16:59 ` [PATCH 02/31] crypto_pool: Add crypto_pool_reserve_scratch() Dmitry Safonov
2022-08-22 10:45 ` Dan Carpenter
2022-08-26 14:42 ` Dmitry Safonov
2022-08-18 16:59 ` [PATCH 03/31] net/tcp: Separate tcp_md5sig_info allocation into tcp_md5sig_info_add() Dmitry Safonov
2022-08-18 16:59 ` [PATCH 04/31] net/tcp: Disable TCP-MD5 static key on tcp_md5sig_info destruction Dmitry Safonov
2022-08-18 16:59 ` [PATCH 05/31] net/tcp: Use crypto_pool for TCP-MD5 Dmitry Safonov
2022-08-18 16:59 ` [PATCH 06/31] net/ipv6: sr: Switch to using crypto_pool Dmitry Safonov
2022-08-18 16:59 ` [PATCH 07/31] tcp: Add TCP-AO config and structures Dmitry Safonov
2022-08-18 16:59 ` [PATCH 08/31] net/tcp: Introduce TCP_AO setsockopt()s Dmitry Safonov
2022-08-18 18:50 ` kernel test robot
2022-08-18 18:50 ` kernel test robot
2022-08-23 14:45 ` Leonard Crestez
2022-08-31 18:48 ` Dmitry Safonov
2022-09-03 9:35 ` Leonard Crestez
2022-08-25 15:31 ` David Ahern
2022-08-25 18:21 ` David Laight
2022-08-18 16:59 ` [PATCH 09/31] net/tcp: Prevent TCP-MD5 with TCP-AO being set Dmitry Safonov
2022-08-18 16:59 ` [PATCH 10/31] net/tcp: Calculate TCP-AO traffic keys Dmitry Safonov
2022-08-18 16:59 ` [PATCH 11/31] net/tcp: Add TCP-AO sign to outgoing packets Dmitry Safonov
2022-08-22 12:03 ` [kbuild] " Dan Carpenter
2022-08-29 17:55 ` Dmitry Safonov
2022-08-18 16:59 ` [PATCH 12/31] net/tcp: Add tcp_parse_auth_options() Dmitry Safonov
2022-08-18 19:00 ` kernel test robot
2022-08-18 16:59 ` [PATCH 13/31] net/tcp: Add AO sign to RST packets Dmitry Safonov
2022-08-18 16:59 ` [PATCH 14/31] net/tcp: Add TCP-AO sign to twsk Dmitry Safonov
2022-08-18 16:59 ` [PATCH 15/31] net/tcp: Wire TCP-AO to request sockets Dmitry Safonov
2022-08-18 16:59 ` [PATCH 16/31] net/tcp: Sign SYN-ACK segments with TCP-AO Dmitry Safonov
2022-08-18 16:59 ` [PATCH 17/31] net/tcp: Verify inbound TCP-AO signed segments Dmitry Safonov
2022-08-18 16:59 ` [PATCH 18/31] net/tcp: Add TCP-AO segments counters Dmitry Safonov
2022-08-18 16:59 ` [PATCH 19/31] net/tcp: Add TCP-AO SNE support Dmitry Safonov
2022-08-23 14:50 ` Leonard Crestez
2022-08-23 22:40 ` Francesco Ruggeri
2022-08-18 16:59 ` [PATCH 20/31] net/tcp: Add tcp_hash_fail() ratelimited logs Dmitry Safonov
2022-08-18 16:59 ` Dmitry Safonov [this message]
2022-08-18 16:59 ` [PATCH 22/31] net/tcp: Add option for TCP-AO to (not) hash header Dmitry Safonov
2022-08-18 16:59 ` [PATCH 23/31] net/tcp: Add getsockopt(TCP_AO_GET) Dmitry Safonov
2022-08-23 14:45 ` Leonard Crestez
2022-08-18 16:59 ` [PATCH 24/31] net/tcp: Allow asynchronous delete for TCP-AO keys (MKTs) Dmitry Safonov
2022-08-18 16:59 ` [PATCH 25/31] selftests/net: Add TCP-AO library Dmitry Safonov
2022-08-23 15:47 ` Shuah Khan
2022-09-05 20:24 ` Dmitry Safonov
2022-09-06 16:34 ` Dmitry Safonov
2022-08-18 17:00 ` [PATCH 26/31] selftests/net: Verify that TCP-AO complies with ignoring ICMPs Dmitry Safonov
2022-08-18 17:00 ` [PATCH 27/31] selftest/net: Add TCP-AO ICMPs accept test Dmitry Safonov
2022-08-18 17:00 ` [PATCH 28/31] selftest/tcp-ao: Add a test for MKT matching Dmitry Safonov
2022-08-18 17:00 ` [PATCH 29/31] selftest/tcp-ao: Add test for TCP-AO add setsockopt() command Dmitry Safonov
2022-08-18 17:00 ` [PATCH 30/31] selftests/tcp-ao: Add TCP-AO + TCP-MD5 + no sign listen socket tests Dmitry Safonov
2022-08-18 17:00 ` [PATCH 31/31] selftests/aolib: Add test/benchmark for removing MKTs Dmitry Safonov
2022-08-21 20:34 ` [PATCH 00/31] net/tcp: Add TCP-AO support Leonard Crestez
2022-08-21 23:51 ` David Ahern
2022-08-22 20:35 ` Dmitry Safonov
2022-08-23 15:30 ` Leonard Crestez
2022-08-23 16:31 ` Dmitry Safonov
2022-08-24 12:46 ` Andrew Lunn
2022-08-24 17:55 ` Jakub Kicinski
2022-08-27 8:55 ` Leonard Crestez
2022-08-22 18:42 ` Salam Noureddine
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220818170005.747015-22-dima@arista.com \
--to=dima@arista.com \
--cc=0x7f454c46@gmail.com \
--cc=ardb@kernel.org \
--cc=cdleonard@gmail.com \
--cc=colona@arista.com \
--cc=davem@davemloft.net \
--cc=dsahern@kernel.org \
--cc=ebiggers@kernel.org \
--cc=edumazet@google.com \
--cc=fruggeri@arista.com \
--cc=gilligan@arista.com \
--cc=herbert@gondor.apana.org.au \
--cc=kuba@kernel.org \
--cc=linux-crypto@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=netdev@vger.kernel.org \
--cc=noureddine@arista.com \
--cc=pabeni@redhat.com \
--cc=shuah@kernel.org \
--cc=yoshfuji@linux-ipv6.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).