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Message-Id: <23d0934b85fa00e8f2aa8ebb1af3005fbed5b347.1635784253.git.cdleonard@gmail.com>
Date: Mon, 1 Nov 2021 18:34:48 +0200
From: Leonard Crestez <cdleonard@...il.com>
To: David Ahern <dsahern@...nel.org>, Shuah Khan <shuah@...nel.org>,
Dmitry Safonov <0x7f454c46@...il.com>,
Eric Dumazet <edumazet@...gle.com>
Cc: "David S. Miller" <davem@...emloft.net>,
Herbert Xu <herbert@...dor.apana.org.au>,
Kuniyuki Iwashima <kuniyu@...zon.co.jp>,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
Jakub Kicinski <kuba@...nel.org>,
Yuchung Cheng <ycheng@...gle.com>,
Francesco Ruggeri <fruggeri@...sta.com>,
Mat Martineau <mathew.j.martineau@...ux.intel.com>,
Christoph Paasch <cpaasch@...le.com>,
Ivan Delalande <colona@...sta.com>,
Priyaranjan Jha <priyarjha@...gle.com>, netdev@...r.kernel.org,
linux-crypto@...r.kernel.org, linux-kselftest@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 13/25] tcp: authopt: Add support for signing skb-less replies
This is required because tcp ipv4 sometimes sends replies without
allocating a full skb that can be signed by tcp authopt.
Handle this with additional code in tcp authopt.
Signed-off-by: Leonard Crestez <cdleonard@...il.com>
---
include/net/tcp_authopt.h | 7 ++
net/ipv4/tcp_authopt.c | 147 ++++++++++++++++++++++++++++++++++++++
2 files changed, 154 insertions(+)
diff --git a/include/net/tcp_authopt.h b/include/net/tcp_authopt.h
index 7360bda20f97..ae7d6a1eab8d 100644
--- a/include/net/tcp_authopt.h
+++ b/include/net/tcp_authopt.h
@@ -101,10 +101,17 @@ static inline struct tcp_authopt_key_info *tcp_authopt_select_key(
int tcp_authopt_hash(
char *hash_location,
struct tcp_authopt_key_info *key,
struct tcp_authopt_info *info,
struct sock *sk, struct sk_buff *skb);
+int tcp_v4_authopt_hash_reply(
+ char *hash_location,
+ struct tcp_authopt_info *info,
+ struct tcp_authopt_key_info *key,
+ __be32 saddr,
+ __be32 daddr,
+ struct tcphdr *th);
int __tcp_authopt_openreq(struct sock *newsk, const struct sock *oldsk, struct request_sock *req);
static inline int tcp_authopt_openreq(
struct sock *newsk,
const struct sock *oldsk,
struct request_sock *req)
diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c
index c9d201d8f7a7..aef63e35b56f 100644
--- a/net/ipv4/tcp_authopt.c
+++ b/net/ipv4/tcp_authopt.c
@@ -799,10 +799,74 @@ static int tcp_authopt_get_traffic_key(struct sock *sk,
out:
tcp_authopt_put_kdf_shash(key, kdf_tfm);
return err;
}
+struct tcp_v4_authopt_context_data {
+ __be32 saddr;
+ __be32 daddr;
+ __be16 sport;
+ __be16 dport;
+ __be32 sisn;
+ __be32 disn;
+ __be16 digestbits;
+} __packed;
+
+static int tcp_v4_authopt_get_traffic_key_noskb(struct tcp_authopt_key_info *key,
+ __be32 saddr,
+ __be32 daddr,
+ __be16 sport,
+ __be16 dport,
+ __be32 sisn,
+ __be32 disn,
+ u8 *traffic_key)
+{
+ int err;
+ struct crypto_shash *kdf_tfm;
+ SHASH_DESC_ON_STACK(desc, kdf_tfm);
+ struct tcp_v4_authopt_context_data data;
+
+ BUILD_BUG_ON(sizeof(data) != 22);
+
+ kdf_tfm = tcp_authopt_get_kdf_shash(key);
+ if (IS_ERR(kdf_tfm))
+ return PTR_ERR(kdf_tfm);
+
+ err = tcp_authopt_setkey(kdf_tfm, key);
+ if (err)
+ goto out;
+
+ desc->tfm = kdf_tfm;
+ err = crypto_shash_init(desc);
+ if (err)
+ goto out;
+
+ // RFC5926 section 3.1.1.1
+ // Separate to keep alignment semi-sane
+ err = crypto_shash_update(desc, "\x01TCP-AO", 7);
+ if (err)
+ return err;
+ data.saddr = saddr;
+ data.daddr = daddr;
+ data.sport = sport;
+ data.dport = dport;
+ data.sisn = sisn;
+ data.disn = disn;
+ data.digestbits = htons(crypto_shash_digestsize(desc->tfm) * 8);
+
+ err = crypto_shash_update(desc, (u8 *)&data, sizeof(data));
+ if (err)
+ goto out;
+ err = crypto_shash_final(desc, traffic_key);
+ if (err)
+ goto out;
+
+out:
+ tcp_authopt_put_kdf_shash(key, kdf_tfm);
+ return err;
+}
+
static int crypto_shash_update_zero(struct shash_desc *desc, int len)
{
u8 zero = 0;
int i, err;
@@ -1205,10 +1269,93 @@ int tcp_authopt_hash(char *hash_location,
memset(hash_location, 0, TCP_AUTHOPT_MACLEN);
return err;
}
EXPORT_SYMBOL(tcp_authopt_hash);
+/**
+ * tcp_v4_authopt_hash_reply - Hash tcp+ipv4 header without SKB
+ *
+ * @hash_location: output buffer
+ * @info: sending socket's tcp_authopt_info
+ * @key: signing key, from tcp_authopt_select_key.
+ * @saddr: source address
+ * @daddr: destination address
+ * @th: Pointer to TCP header and options
+ */
+int tcp_v4_authopt_hash_reply(char *hash_location,
+ struct tcp_authopt_info *info,
+ struct tcp_authopt_key_info *key,
+ __be32 saddr,
+ __be32 daddr,
+ struct tcphdr *th)
+{
+ struct crypto_shash *mac_tfm;
+ u8 macbuf[TCP_AUTHOPT_MAXMACBUF];
+ u8 traffic_key[TCP_AUTHOPT_MAX_TRAFFIC_KEY_LEN];
+ SHASH_DESC_ON_STACK(desc, tfm);
+ __be32 sne = 0;
+ int err;
+
+ /* Call special code path for computing traffic key without skb
+ * This can be called from tcp_v4_reqsk_send_ack so caching would be
+ * difficult here.
+ */
+ err = tcp_v4_authopt_get_traffic_key_noskb(key, saddr, daddr,
+ th->source, th->dest,
+ htonl(info->src_isn), htonl(info->dst_isn),
+ traffic_key);
+ if (err)
+ goto out_err_traffic_key;
+
+ /* Init mac shash */
+ mac_tfm = tcp_authopt_get_mac_shash(key);
+ if (IS_ERR(mac_tfm))
+ return PTR_ERR(mac_tfm);
+ err = crypto_shash_setkey(mac_tfm, traffic_key, key->alg->traffic_key_len);
+ if (err)
+ goto out_err;
+
+ desc->tfm = mac_tfm;
+ err = crypto_shash_init(desc);
+ if (err)
+ return err;
+
+ err = crypto_shash_update(desc, (u8 *)&sne, 4);
+ if (err)
+ return err;
+
+ err = tcp_authopt_hash_tcp4_pseudoheader(desc, saddr, daddr, th->doff * 4);
+ if (err)
+ return err;
+
+ // TCP header with checksum set to zero. Caller ensures this.
+ if (WARN_ON_ONCE(th->check != 0))
+ goto out_err;
+ err = crypto_shash_update(desc, (u8 *)th, sizeof(*th));
+ if (err)
+ goto out_err;
+
+ // TCP options
+ err = tcp_authopt_hash_opts(desc, th, !(key->flags & TCP_AUTHOPT_KEY_EXCLUDE_OPTS));
+ if (err)
+ goto out_err;
+
+ err = crypto_shash_final(desc, macbuf);
+ if (err)
+ goto out_err;
+ memcpy(hash_location, macbuf, TCP_AUTHOPT_MACLEN);
+
+ tcp_authopt_put_mac_shash(key, mac_tfm);
+ return 0;
+
+out_err:
+ tcp_authopt_put_mac_shash(key, mac_tfm);
+out_err_traffic_key:
+ memset(hash_location, 0, TCP_AUTHOPT_MACLEN);
+ return err;
+}
+
static struct tcp_authopt_key_info *tcp_authopt_lookup_recv(struct sock *sk,
struct sk_buff *skb,
struct tcp_authopt_info *info,
int recv_id)
{
--
2.25.1
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