Hi Leonard,
On 11/1/21 16:34, Leonard Crestez wrote:
[..]
+struct tcp_authopt_key {[..]
+ /** @flags: Combination of &enum tcp_authopt_key_flag */
+ __u32 flags;
+ /** @send_id: keyid value for send */
+ __u8 send_id;
+ /** @recv_id: keyid value for receive */
+ __u8 recv_id;
+ /** @alg: One of &enum tcp_authopt_alg */
+ __u8 alg;
+ /** @keylen: Length of the key buffer */
+ __u8 keylen;
+ /** @key: Secret key */
+ __u8 key[TCP_AUTHOPT_MAXKEYLEN];
+ /**
+ * @addr: Key is only valid for this address
+ *
+ * Ignored unless TCP_AUTHOPT_KEY_ADDR_BIND flag is set
+ */
+ struct __kernel_sockaddr_storage addr;
+};
+/* Free key nicely, for living sockets */[..]
+static void tcp_authopt_key_del(struct sock *sk,
+ struct tcp_authopt_info *info,
+ struct tcp_authopt_key_info *key)
+{
+ sock_owned_by_me(sk);
+ hlist_del_rcu(&key->node);
+ atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
+ kfree_rcu(key, rcu);
+}
+#define TCP_AUTHOPT_KEY_KNOWN_FLAGS ( \[..]
+ TCP_AUTHOPT_KEY_DEL | \
+ TCP_AUTHOPT_KEY_EXCLUDE_OPTS | \
+ TCP_AUTHOPT_KEY_ADDR_BIND)
+
+int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen)
+{
+ /* Delete is a special case: */
+ if (opt.flags & TCP_AUTHOPT_KEY_DEL) {
+ info = rcu_dereference_check(tcp_sk(sk)->authopt_info, lockdep_sock_is_held(sk));
+ if (!info)
+ return -ENOENT;
+ key_info = tcp_authopt_key_lookup_exact(sk, info, &opt);
+ if (!key_info)
+ return -ENOENT;
+ tcp_authopt_key_del(sk, info, key_info);
+ return 0;
I remember we discussed it in RFC, that removing a key that's currently
in use may result in random MKT to be used.
I think, it's possible to make this API a bit more predictable if:
- DEL command fails to remove a key that is current/receive_next;
- opt.flags has CURR/NEXT flag that has corresponding `u8 current_key`
and `u8 receive_next` values. As socket lock is held - that makes
current_key/receive_next change atomic with deletion of an existing key
that might have been in use.
In result user may remove a key that's not in use or has to set new
current/next. Which avoids the issue with random MKT being used to sign
segments.