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Message-ID: <20190424200757.0978cbd2@cakuba.netronome.com>
Date: Wed, 24 Apr 2019 20:07:57 -0700
From: Jakub Kicinski <jakub.kicinski@...ronome.com>
To: John Fastabend <john.fastabend@...il.com>
Cc: ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
bpf@...r.kernel.org
Subject: Re: [bpf PATCH 1/3] bpf: tls, implement unhash to avoid transition
out of ESTABLISHED
On Wed, 24 Apr 2019 12:21:03 -0700, John Fastabend wrote:
> It is possible (via shutdown()) for TCP socks to go through TCP_CLOSE
> state via tcp_disconnect() without calling into close callback. This
> would allow a kTLS enabled socket to exist outside of ESTABLISHED
> state which is not supported.
>
> Solve this the same way we solved the sock{map|hash} case by adding
> an unhash hook to remove tear down the TLS state.
>
> In the process we also make the close hook more robust. We add a put
> call into the close path, also in the unhash path, to remove the
> reference to ulp data after free. Its no longer valid and may confuse
> things later if the socket (re)enters kTLS code paths. Second we add
> an 'if(ctx)' check to ensure the ctx is still valid and not released
> from a previous unhash/close path.
>
> Fixes: d91c3e17f75f2 ("net/tls: Only attach to sockets in ESTABLISHED state")
> Reported-by: Eric Dumazet <edumazet@...gle.com>
> Signed-off-by: John Fastabend <john.fastabend@...il.com>
Ah, EDOESNTBUILD, now I get to nitpick too? :)
> diff --git a/include/net/tls.h b/include/net/tls.h
> index d9d0ac66f040..ae13ea19b375 100644
> --- a/include/net/tls.h
> +++ b/include/net/tls.h
> @@ -266,6 +266,8 @@ struct tls_context {
> void (*sk_write_space)(struct sock *sk);
> void (*sk_destruct)(struct sock *sk);
> void (*sk_proto_close)(struct sock *sk, long timeout);
> + void (*sk_proto_unhash)(struct sock *sk);
> + struct proto *sk_proto;
>
> int (*setsockopt)(struct sock *sk, int level,
> int optname, char __user *optval,
> @@ -303,7 +305,7 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
> int tls_sw_sendpage(struct sock *sk, struct page *page,
> int offset, size_t size, int flags);
> void tls_sw_close(struct sock *sk, long timeout);
> -void tls_sw_free_resources_tx(struct sock *sk);
> +void tls_sw_free_resources_tx(struct sock *sk, bool locked);
> void tls_sw_free_resources_rx(struct sock *sk);
> void tls_sw_release_resources_rx(struct sock *sk);
> int tls_sw_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
> @@ -504,6 +506,16 @@ static inline void xor_iv_with_seq(int version, char *iv, char *seq)
> }
> }
>
> +static inline void tls_put_ctx(struct sock *sk)
> +{
> + struct inet_connection_sock *icsk = inet_csk(sk);
> + struct tls_context *ctx = icsk->icsk_ulp_data;
> +
> + if (!ctx)
> + return;
> + sk->sk_prot = ctx->sk_proto;
> + icsk->icsk_ulp_data = NULL;
> +}
>
> static inline struct tls_sw_context_rx *tls_sw_ctx_rx(
> const struct tls_context *tls_ctx)
> diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
> index 7e546b8ec000..2973048957bd 100644
> --- a/net/tls/tls_main.c
> +++ b/net/tls/tls_main.c
> @@ -261,23 +261,16 @@ static void tls_ctx_free(struct tls_context *ctx)
> kfree(ctx);
> }
>
> -static void tls_sk_proto_close(struct sock *sk, long timeout)
> +static bool tls_sk_proto_destroy(struct sock *sk,
> + struct tls_context *ctx, bool destroy)
perhaps this destroy should rather be called locked? It doesn't really
control destroying AFACT..
> {
> - struct tls_context *ctx = tls_get_ctx(sk);
> long timeo = sock_sndtimeo(sk, 0);
> - void (*sk_proto_close)(struct sock *sk, long timeout);
> - bool free_ctx = false;
> -
> - lock_sock(sk);
> - sk_proto_close = ctx->sk_proto_close;
>
> if (ctx->tx_conf == TLS_HW_RECORD && ctx->rx_conf == TLS_HW_RECORD)
> - goto skip_tx_cleanup;
> + return false;
>
> - if (ctx->tx_conf == TLS_BASE && ctx->rx_conf == TLS_BASE) {
> - free_ctx = true;
> - goto skip_tx_cleanup;
> - }
> + if (ctx->tx_conf == TLS_BASE && ctx->rx_conf == TLS_BASE)
> + return true;
>
> if (!tls_complete_pending_work(sk, ctx, 0, &timeo))
> tls_handle_open_record(sk, 0);
> @@ -286,10 +279,10 @@ static void tls_sk_proto_close(struct sock *sk, long timeout)
> if (ctx->tx_conf == TLS_SW) {
> kfree(ctx->tx.rec_seq);
> kfree(ctx->tx.iv);
> - tls_sw_free_resources_tx(sk);
> + tls_sw_free_resources_tx(sk, destroy);
> #ifdef CONFIG_TLS_DEVICE
> } else if (ctx->tx_conf == TLS_HW) {
> - tls_device_free_resources_tx(sk);
> + tls_device_free_resources_tx(sk, destroy);
this part breaks the build tls_device_free_resources_tx() doesn't need
changes. tls_device_offload_cleanup_rx() will though, cause it sleeps.
> #endif
> }
>
> @@ -310,8 +303,39 @@ static void tls_sk_proto_close(struct sock *sk, long timeout)
> tls_ctx_free(ctx);
> ctx = NULL;
> }
> + return false;
> +}
> +
> +static void tls_sk_proto_unhash(struct sock *sk)
> +{
> + struct tls_context *ctx = tls_get_ctx(sk);
> + void (*sk_proto_unhash)(struct sock *sk);
> + bool free_ctx;
> +
> + if (!ctx)
> + return sk->sk_prot->unhash(sk);
> + sk_proto_unhash = ctx->sk_proto_unhash;
> + free_ctx = tls_sk_proto_destroy(sk, ctx, false);
> + tls_put_ctx(sk);
> + if (sk_proto_unhash)
> + sk_proto_unhash(sk);
> + if (free_ctx)
> + tls_ctx_free(ctx);
> +}
>
> -skip_tx_cleanup:
> +static void tls_sk_proto_close(struct sock *sk, long timeout)
> +{
> + struct tls_context *ctx = tls_get_ctx(sk);
> + void (*sk_proto_close)(struct sock *sk, long timeout);
reverse xmas tree
> + bool free_ctx;
> +
> + if (!ctx)
> + return sk->sk_prot->destroy(sk);
> +
> + lock_sock(sk);
> + sk_proto_close = ctx->sk_proto_close;
> + free_ctx = tls_sk_proto_destroy(sk, ctx, true);
> + tls_put_ctx(sk);
> release_sock(sk);
> sk_proto_close(sk, timeout);
> /* free ctx for TLS_HW_RECORD, used by tcp_set_state
> @@ -609,6 +633,8 @@ static struct tls_context *create_ctx(struct sock *sk)
> ctx->setsockopt = sk->sk_prot->setsockopt;
> ctx->getsockopt = sk->sk_prot->getsockopt;
> ctx->sk_proto_close = sk->sk_prot->close;
> + ctx->sk_proto_unhash = sk->sk_prot->unhash;
> + ctx->sk_proto = sk->sk_prot;
> return ctx;
> }
>
> @@ -732,6 +758,7 @@ static void build_protos(struct proto prot[TLS_NUM_CONFIG][TLS_NUM_CONFIG],
> prot[TLS_BASE][TLS_BASE].setsockopt = tls_setsockopt;
> prot[TLS_BASE][TLS_BASE].getsockopt = tls_getsockopt;
> prot[TLS_BASE][TLS_BASE].close = tls_sk_proto_close;
> + prot[TLS_BASE][TLS_BASE].unhash = tls_sk_proto_unhash;
>
> prot[TLS_SW][TLS_BASE] = prot[TLS_BASE][TLS_BASE];
> prot[TLS_SW][TLS_BASE].sendmsg = tls_sw_sendmsg;
> diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
> index f780b473827b..0577633c319b 100644
> --- a/net/tls/tls_sw.c
> +++ b/net/tls/tls_sw.c
> @@ -2044,7 +2044,7 @@ static void tls_data_ready(struct sock *sk)
> }
> }
>
> -void tls_sw_free_resources_tx(struct sock *sk)
> +void tls_sw_free_resources_tx(struct sock *sk, bool locked)
> {
> struct tls_context *tls_ctx = tls_get_ctx(sk);
> struct tls_sw_context_tx *ctx = tls_sw_ctx_tx(tls_ctx);
> @@ -2055,9 +2055,11 @@ void tls_sw_free_resources_tx(struct sock *sk)
> if (atomic_read(&ctx->encrypt_pending))
> crypto_wait_req(-EINPROGRESS, &ctx->async_wait);
>
> - release_sock(sk);
> + if (locked)
> + release_sock(sk);
> cancel_delayed_work_sync(&ctx->tx_work.work);
> - lock_sock(sk);
> + if (locked)
> + lock_sock(sk);
>
> /* Tx whatever records we can transmit and abandon the rest */
> tls_tx_records(sk, -1);
> @@ -2080,7 +2082,10 @@ void tls_sw_free_resources_tx(struct sock *sk)
> kfree(rec);
> }
>
> - crypto_free_aead(ctx->aead_send);
> + if (ctx->aead_send) {
> + crypto_free_aead(ctx->aead_send);
> + ctx->aead_send = NULL;
> + }
> tls_free_open_rec(sk);
>
> kfree(ctx);
>
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