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.
Signed-off-by: Sabrina Dubroca sd@queasysnail.net --- include/net/tls.h | 4 ++++ net/tls/tls_sw.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 48 insertions(+)
diff --git a/include/net/tls.h b/include/net/tls.h index 154949c7b0c8..297732f23804 100644 --- a/include/net/tls.h +++ b/include/net/tls.h @@ -69,8 +69,11 @@ extern const struct tls_cipher_size_desc tls_cipher_size_desc[];
#define TLS_CRYPTO_INFO_READY(info) ((info)->cipher_type)
+#define TLS_RECORD_TYPE_HANDSHAKE 0x16 #define TLS_RECORD_TYPE_DATA 0x17
+#define TLS_HANDSHAKE_KEYUPDATE 24 /* rfc8446 B.3: Key update */ + #define TLS_AAD_SPACE_SIZE 13
#define MAX_IV_SIZE 16 @@ -145,6 +148,7 @@ struct tls_sw_context_rx {
struct tls_strparser strp;
+ bool key_update_pending; atomic_t decrypt_pending; /* protect crypto_wait with decrypt_pending*/ spinlock_t decrypt_compl_lock; diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index 238bd18c5eb6..149a39d9a56a 100644 --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -1687,6 +1687,33 @@ 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) { @@ -1706,6 +1733,10 @@ 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; }
@@ -1957,6 +1988,12 @@ int tls_sw_recvmsg(struct sock *sk, struct tls_decrypt_arg darg; int to_decrypt, chunk;
+ /* a rekey is pending, let userspace deal with it */ + if (unlikely(ctx->key_update_pending)) { + err = -EKEYEXPIRED; + break; + } + err = tls_rx_rec_wait(sk, psock, flags & MSG_DONTWAIT, released); if (err <= 0) { @@ -2141,6 +2178,12 @@ ssize_t tls_sw_splice_read(struct socket *sock, loff_t *ppos, if (err < 0) return err;
+ /* a rekey is pending, let userspace deal with it */ + if (unlikely(ctx->key_update_pending)) { + err = -EKEYEXPIRED; + goto splice_read_end; + } + if (!skb_queue_empty(&ctx->rx_list)) { skb = __skb_dequeue(&ctx->rx_list); } else { @@ -2526,6 +2569,7 @@ 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) {