| Message ID | eae51cdb1d15c914577a88fb5cd9d1c4b1121642.1691584074.git.sd@queasysnail.net (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | tls: implement key updates for TLS1.3 | expand |
On Wed, Aug 09, 2023 at 02:58:51PM +0200, Sabrina Dubroca wrote: > 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; Hi Sabrina, Would it make sense for this to be u8 key_update_pending:1; > > 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); nit: reverse xmas tree > + > + 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) { > -- > 2.40.1 > >
On Wed, 9 Aug 2023 14:58:51 +0200 Sabrina Dubroca wrote: > +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) { unlikely() does the nachine code look worse if we flip the condition and return early instead of indenting the entire function? > + char hs_type; > + int err; I'd probably err on the side of declaring those on the outside, but if we don't we should move rxm in here, it's not needed outside. Either, or. > + 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); feels a bit like we should just pass ctx rather than sk? > + struct tls_sw_context_rx *rx_ctx = ctx->priv_ctx_rx; > + > + rx_ctx->key_update_pending = true; > + } > + } > + > + return 0; > +}
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) {
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(+)