When a TLS handshake record carrying a KeyUpdate message is received, all subsequent records will be encrypted with a new key. We need to stop decrypting incoming records with the old key, and wait until userspace provides a new key.
Make a note of this in the RX context just after decrypting that record, and stop recvmsg/splice calls with EKEYEXPIRED until the new key is available.
v3: - move key_update_pending check into tls_rx_rec_wait (Jakub) - TLS_RECORD_TYPE_HANDSHAKE was added to include/net/tls_prot.h by the tls handshake series, drop that from this patch - move key_update_pending into an existing hole
Signed-off-by: Sabrina Dubroca sd@queasysnail.net --- include/net/tls.h | 3 +++ net/tls/tls_sw.c | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+)
diff --git a/include/net/tls.h b/include/net/tls.h index 06fca9160346..219a4f38c0e4 100644 --- a/include/net/tls.h +++ b/include/net/tls.h @@ -69,6 +69,8 @@ extern const struct tls_cipher_size_desc tls_cipher_size_desc[];
#define TLS_CRYPTO_INFO_READY(info) ((info)->cipher_type)
+#define TLS_HANDSHAKE_KEYUPDATE 24 /* rfc8446 B.3: Key update */ + #define TLS_AAD_SPACE_SIZE 13
#define MAX_IV_SIZE 16 @@ -141,6 +143,7 @@ struct tls_sw_context_rx { u8 async_capable:1; u8 zc_capable:1; u8 reader_contended:1; + bool key_update_pending;
struct tls_strparser strp;
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index 2ca0eb90a2a5..497f56c5f169 100644 --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -1293,6 +1293,10 @@ tls_rx_rec_wait(struct sock *sk, struct sk_psock *psock, bool nonblock, DEFINE_WAIT_FUNC(wait, woken_wake_function); long timeo;
+ /* a rekey is pending, let userspace deal with it */ + if (unlikely(ctx->key_update_pending)) + return -EKEYEXPIRED; + timeo = sock_rcvtimeo(sk, nonblock);
while (!tls_strp_msg_ready(ctx)) { @@ -1689,6 +1693,33 @@ tls_decrypt_device(struct sock *sk, struct msghdr *msg, return 1; }
+static int tls_check_pending_rekey(struct sock *sk, struct sk_buff *skb) +{ + const struct tls_msg *tlm = tls_msg(skb); + const struct strp_msg *rxm = strp_msg(skb); + + if (tlm->control == TLS_RECORD_TYPE_HANDSHAKE) { + char hs_type; + int err; + + if (rxm->full_len < 1) + return -EINVAL; + + err = skb_copy_bits(skb, rxm->offset, &hs_type, 1); + if (err < 0) + return err; + + if (hs_type == TLS_HANDSHAKE_KEYUPDATE) { + struct tls_context *ctx = tls_get_ctx(sk); + struct tls_sw_context_rx *rx_ctx = ctx->priv_ctx_rx; + + rx_ctx->key_update_pending = true; + } + } + + return 0; +} + static int tls_rx_one_record(struct sock *sk, struct msghdr *msg, struct tls_decrypt_arg *darg) { @@ -1708,6 +1739,10 @@ static int tls_rx_one_record(struct sock *sk, struct msghdr *msg, rxm->full_len -= prot->overhead_size; tls_advance_record_sn(sk, prot, &tls_ctx->rx);
+ err = tls_check_pending_rekey(sk, darg->skb); + if (err < 0) + return err; + return 0; }
@@ -2642,6 +2677,7 @@ int tls_set_sw_offload(struct sock *sk, int tx) skb_queue_head_init(&sw_ctx_rx->rx_list); skb_queue_head_init(&sw_ctx_rx->async_hold); aead = &sw_ctx_rx->aead_recv; + sw_ctx_rx->key_update_pending = false; }
switch (crypto_info->cipher_type) {