[PATCH v9 net-next 07/23] net/tcp: Add tcp_parse_auth_options()
From: Dmitry Safonov
Date: Wed Aug 02 2023 - 13:28:36 EST
Introduce a helper that:
(1) shares the common code with TCP-MD5 header options parsing
(2) looks for hash signature only once for both TCP-MD5 and TCP-AO
(3) fails with -EEXIST if any TCP sign option is present twice, see
RFC5925 (2.2):
">> A single TCP segment MUST NOT have more than one TCP-AO in its
options sequence. When multiple TCP-AOs appear, TCP MUST discard
the segment."
Co-developed-by: Francesco Ruggeri <fruggeri@xxxxxxxxxx>
Signed-off-by: Francesco Ruggeri <fruggeri@xxxxxxxxxx>
Co-developed-by: Salam Noureddine <noureddine@xxxxxxxxxx>
Signed-off-by: Salam Noureddine <noureddine@xxxxxxxxxx>
Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>
Acked-by: David Ahern <dsahern@xxxxxxxxxx>
---
include/net/dropreason-core.h | 6 ++++++
include/net/tcp.h | 24 ++++++++++++++++++++-
include/net/tcp_ao.h | 17 ++++++++++++++-
net/ipv4/tcp.c | 3 ++-
net/ipv4/tcp_input.c | 39 ++++++++++++++++++++++++++---------
net/ipv4/tcp_ipv4.c | 15 +++++++++-----
net/ipv6/tcp_ipv6.c | 11 ++++++----
7 files changed, 93 insertions(+), 22 deletions(-)
diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h
index f291a3b0f9e5..05255bffa2c8 100644
--- a/include/net/dropreason-core.h
+++ b/include/net/dropreason-core.h
@@ -20,6 +20,7 @@
FN(IP_NOPROTO) \
FN(SOCKET_RCVBUFF) \
FN(PROTO_MEM) \
+ FN(TCP_AUTH_HDR) \
FN(TCP_MD5NOTFOUND) \
FN(TCP_MD5UNEXPECTED) \
FN(TCP_MD5FAILURE) \
@@ -140,6 +141,11 @@ enum skb_drop_reason {
* drop out of udp_memory_allocated.
*/
SKB_DROP_REASON_PROTO_MEM,
+ /**
+ * @SKB_DROP_REASON_TCP_AUTH_HDR: TCP-MD5 or TCP-AO hashes are met
+ * twice or set incorrectly.
+ */
+ SKB_DROP_REASON_TCP_AUTH_HDR,
/**
* @SKB_DROP_REASON_TCP_MD5NOTFOUND: no MD5 hash and one expected,
* corresponding to LINUX_MIB_TCPMD5NOTFOUND
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 73e6730fc3e6..a09b5b53a834 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -427,7 +427,6 @@ int tcp_mmap(struct file *file, struct socket *sock,
void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
struct tcp_options_received *opt_rx,
int estab, struct tcp_fastopen_cookie *foc);
-const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
/*
* BPF SKB-less helpers
@@ -2574,6 +2573,29 @@ static inline u64 tcp_transmit_time(const struct sock *sk)
return 0;
}
+static inline int tcp_parse_auth_options(const struct tcphdr *th,
+ const u8 **md5_hash, const struct tcp_ao_hdr **aoh)
+{
+ const u8 *md5_tmp, *ao_tmp;
+ int ret;
+
+ ret = tcp_do_parse_auth_options(th, &md5_tmp, &ao_tmp);
+ if (ret)
+ return ret;
+
+ if (md5_hash)
+ *md5_hash = md5_tmp;
+
+ if (aoh) {
+ if (!ao_tmp)
+ *aoh = NULL;
+ else
+ *aoh = (struct tcp_ao_hdr *)(ao_tmp - 2);
+ }
+
+ return 0;
+}
+
static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
int family)
{
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index cd85d292f78e..e685ad9db949 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -148,7 +148,9 @@ int tcp_v6_ao_hash_skb(char *ao_hash, struct tcp_ao_key *key,
int tcp_v6_parse_ao(struct sock *sk, int cmd, sockptr_t optval, int optlen);
void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb);
void tcp_ao_connect_init(struct sock *sk);
-
+void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb,
+ struct tcp_request_sock *treq,
+ unsigned short int family);
#else /* CONFIG_TCP_AO */
static inline struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,
@@ -170,4 +172,17 @@ static inline void tcp_ao_connect_init(struct sock *sk)
}
#endif
+#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
+int tcp_do_parse_auth_options(const struct tcphdr *th,
+ const u8 **md5_hash, const u8 **ao_hash);
+#else
+static inline int tcp_do_parse_auth_options(const struct tcphdr *th,
+ const u8 **md5_hash, const u8 **ao_hash)
+{
+ *md5_hash = NULL;
+ *ao_hash = NULL;
+ return 0;
+}
+#endif
+
#endif /* _TCP_AO_H */
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 9a94910f7ff7..2547a9a6ac57 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -4397,7 +4397,8 @@ tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
l3index = sdif ? dif : 0;
hash_expected = tcp_md5_do_lookup(sk, l3index, saddr, family);
- hash_location = tcp_parse_md5sig_option(th);
+ if (tcp_parse_auth_options(th, &hash_location, NULL))
+ return SKB_DROP_REASON_TCP_AUTH_HDR;
/* We've parsed the options - do we have a hash? */
if (!hash_expected && !hash_location)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 7780ceef3415..d9241385468a 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4212,39 +4212,58 @@ static bool tcp_fast_parse_options(const struct net *net,
return true;
}
-#ifdef CONFIG_TCP_MD5SIG
+#if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
/*
- * Parse MD5 Signature option
+ * Parse Signature options
*/
-const u8 *tcp_parse_md5sig_option(const struct tcphdr *th)
+int tcp_do_parse_auth_options(const struct tcphdr *th,
+ const u8 **md5_hash, const u8 **ao_hash)
{
int length = (th->doff << 2) - sizeof(*th);
const u8 *ptr = (const u8 *)(th + 1);
+ unsigned int minlen = TCPOLEN_MD5SIG;
+
+ if (IS_ENABLED(CONFIG_TCP_AO))
+ minlen = sizeof(struct tcp_ao_hdr) + 1;
+
+ *md5_hash = NULL;
+ *ao_hash = NULL;
/* If not enough data remaining, we can short cut */
- while (length >= TCPOLEN_MD5SIG) {
+ while (length >= minlen) {
int opcode = *ptr++;
int opsize;
switch (opcode) {
case TCPOPT_EOL:
- return NULL;
+ return 0;
case TCPOPT_NOP:
length--;
continue;
default:
opsize = *ptr++;
if (opsize < 2 || opsize > length)
- return NULL;
- if (opcode == TCPOPT_MD5SIG)
- return opsize == TCPOLEN_MD5SIG ? ptr : NULL;
+ return -EINVAL;
+ if (opcode == TCPOPT_MD5SIG) {
+ if (opsize != TCPOLEN_MD5SIG)
+ return -EINVAL;
+ if (unlikely(*md5_hash || *ao_hash))
+ return -EEXIST;
+ *md5_hash = ptr;
+ } else if (opcode == TCPOPT_AO) {
+ if (opsize <= sizeof(struct tcp_ao_hdr))
+ return -EINVAL;
+ if (unlikely(*md5_hash || *ao_hash))
+ return -EEXIST;
+ *ao_hash = ptr;
+ }
}
ptr += opsize - 2;
length -= opsize;
}
- return NULL;
+ return 0;
}
-EXPORT_SYMBOL(tcp_parse_md5sig_option);
+EXPORT_SYMBOL(tcp_do_parse_auth_options);
#endif
/* Sorry, PAWS as specified is broken wrt. pure-ACKs -DaveM
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index de7dfafa175e..8649ff94017f 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -670,7 +670,9 @@ EXPORT_SYMBOL(tcp_v4_send_check);
* Exception: precedence violation. We do not implement it in any case.
*/
-#ifdef CONFIG_TCP_MD5SIG
+#ifdef CONFIG_TCP_AO
+#define OPTION_BYTES MAX_TCP_OPTION_SPACE
+#elif defined(CONFIG_TCP_MD5SIG)
#define OPTION_BYTES TCPOLEN_MD5SIG_ALIGNED
#else
#define OPTION_BYTES sizeof(__be32)
@@ -685,8 +687,8 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
} rep;
struct ip_reply_arg arg;
#ifdef CONFIG_TCP_MD5SIG
+ const __u8 *md5_hash_location = NULL;
struct tcp_md5sig_key *key = NULL;
- const __u8 *hash_location = NULL;
unsigned char newhash[16];
int genhash;
struct sock *sk1 = NULL;
@@ -727,8 +729,11 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
#ifdef CONFIG_TCP_MD5SIG
+ /* Invalid TCP option size or twice included auth */
+ if (tcp_parse_auth_options(tcp_hdr(skb), &md5_hash_location, NULL))
+ return;
+
rcu_read_lock();
- hash_location = tcp_parse_md5sig_option(th);
if (sk && sk_fullsock(sk)) {
const union tcp_md5_addr *addr;
int l3index;
@@ -739,7 +744,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
l3index = tcp_v4_sdif(skb) ? inet_iif(skb) : 0;
addr = (union tcp_md5_addr *)&ip_hdr(skb)->saddr;
key = tcp_md5_do_lookup(sk, l3index, addr, AF_INET);
- } else if (hash_location) {
+ } else if (md5_hash_location) {
const union tcp_md5_addr *addr;
int sdif = tcp_v4_sdif(skb);
int dif = inet_iif(skb);
@@ -771,7 +776,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
genhash = tcp_v4_md5_hash_skb(newhash, key, NULL, skb);
- if (genhash || memcmp(hash_location, newhash, 16) != 0)
+ if (genhash || memcmp(md5_hash_location, newhash, 16) != 0)
goto out;
}
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 8200a7e79c79..6b943b4345a7 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -989,7 +989,7 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
u32 seq = 0, ack_seq = 0;
struct tcp_md5sig_key *key = NULL;
#ifdef CONFIG_TCP_MD5SIG
- const __u8 *hash_location = NULL;
+ const __u8 *md5_hash_location = NULL;
unsigned char newhash[16];
int genhash;
struct sock *sk1 = NULL;
@@ -1011,8 +1011,11 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
#ifdef CONFIG_TCP_MD5SIG
+ /* Invalid TCP option size or twice included auth */
+ if (tcp_parse_auth_options(th, &md5_hash_location, NULL))
+ return;
+
rcu_read_lock();
- hash_location = tcp_parse_md5sig_option(th);
if (sk && sk_fullsock(sk)) {
int l3index;
@@ -1021,7 +1024,7 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
*/
l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
key = tcp_v6_md5_do_lookup(sk, &ipv6h->saddr, l3index);
- } else if (hash_location) {
+ } else if (md5_hash_location) {
int dif = tcp_v6_iif_l3_slave(skb);
int sdif = tcp_v6_sdif(skb);
int l3index;
@@ -1050,7 +1053,7 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
goto out;
genhash = tcp_v6_md5_hash_skb(newhash, key, NULL, skb);
- if (genhash || memcmp(hash_location, newhash, 16) != 0)
+ if (genhash || memcmp(md5_hash_location, newhash, 16) != 0)
goto out;
}
#endif
--
2.41.0