diff mbox series

[net-next,v5,2/6] tls: implement rekey for TLS1.3

Message ID a4278b8f7a396daf7e5cdc1c435a46346cf09aa9.1734013874.git.sd@queasysnail.net (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series tls: implement key updates for TLS1.3 | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 4 maintainers not CCed: pabeni@redhat.com edumazet@google.com linux-hardening@vger.kernel.org kees@kernel.org
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1 this patch: 1
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 274 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Sabrina Dubroca Dec. 12, 2024, 3:36 p.m. UTC 
This adds the possibility to change the key and IV when using
TLS1.3. Changing the cipher or TLS version is not supported.

Once we have updated the RX key, we can unblock the receive side. If
the rekey fails, the context is unmodified and userspace is free to
retry the update or close the socket.

This change only affects tls_sw, since 1.3 offload isn't supported.

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: Jakub Kicinski <kuba@kernel.org>
---
v2:
 - reverse xmas tree
 - turn the alt_crypto_info into an else if
 - don't modify the context when rekey fails

v3:
 - only call tls_sw_strparser_arm when setting the initial RX key, not
   on rekeys
 - update tls_sk_poll to not say the socket is readable when we're
   waiting for a rekey, and wake up poll() when the new key is installed
 - use unsafe_memcpy to make FORTIFY_SOURCE happy

v4:
 - rebase on top of current net-next
 - no {} needed around single line (Simon)

v5: unchanged, keep Jakub's ack from v4

 net/tls/tls.h        |   3 +-
 net/tls/tls_device.c |   2 +-
 net/tls/tls_main.c   |  46 ++++++++++++++-----
 net/tls/tls_sw.c     | 105 +++++++++++++++++++++++++++++--------------
 4 files changed, 108 insertions(+), 48 deletions(-)
diff mbox series

Patch

diff --git a/net/tls/tls.h b/net/tls/tls.h
index e5e47452308a..774859b63f0d 100644
--- a/net/tls/tls.h
+++ b/net/tls/tls.h
@@ -145,7 +145,8 @@  void tls_err_abort(struct sock *sk, int err);
 int init_prot_info(struct tls_prot_info *prot,
 		   const struct tls_crypto_info *crypto_info,
 		   const struct tls_cipher_desc *cipher_desc);
-int tls_set_sw_offload(struct sock *sk, int tx);
+int tls_set_sw_offload(struct sock *sk, int tx,
+		       struct tls_crypto_info *new_crypto_info);
 void tls_update_rx_zc_capable(struct tls_context *tls_ctx);
 void tls_sw_strparser_arm(struct sock *sk, struct tls_context *ctx);
 void tls_sw_strparser_done(struct tls_context *tls_ctx);
diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index dc063c2c7950..e50b6e71df13 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -1227,7 +1227,7 @@  int tls_set_device_offload_rx(struct sock *sk, struct tls_context *ctx)
 	context->resync_nh_reset = 1;
 
 	ctx->priv_ctx_rx = context;
-	rc = tls_set_sw_offload(sk, 0);
+	rc = tls_set_sw_offload(sk, 0, NULL);
 	if (rc)
 		goto release_ctx;
 
diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 6b4b9f2749a6..68b5735dafc1 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -423,9 +423,10 @@  static __poll_t tls_sk_poll(struct file *file, struct socket *sock,
 	ctx = tls_sw_ctx_rx(tls_ctx);
 	psock = sk_psock_get(sk);
 
-	if (skb_queue_empty_lockless(&ctx->rx_list) &&
-	    !tls_strp_msg_ready(ctx) &&
-	    sk_psock_queue_empty(psock))
+	if ((skb_queue_empty_lockless(&ctx->rx_list) &&
+	     !tls_strp_msg_ready(ctx) &&
+	     sk_psock_queue_empty(psock)) ||
+	    READ_ONCE(ctx->key_update_pending))
 		mask &= ~(EPOLLIN | EPOLLRDNORM);
 
 	if (psock)
@@ -612,11 +613,13 @@  static int validate_crypto_info(const struct tls_crypto_info *crypto_info,
 static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 				  unsigned int optlen, int tx)
 {
-	struct tls_crypto_info *crypto_info;
-	struct tls_crypto_info *alt_crypto_info;
+	struct tls_crypto_info *crypto_info, *alt_crypto_info;
+	struct tls_crypto_info *old_crypto_info = NULL;
 	struct tls_context *ctx = tls_get_ctx(sk);
 	const struct tls_cipher_desc *cipher_desc;
 	union tls_crypto_context *crypto_ctx;
+	union tls_crypto_context tmp = {};
+	bool update = false;
 	int rc = 0;
 	int conf;
 
@@ -633,9 +636,18 @@  static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 
 	crypto_info = &crypto_ctx->info;
 
-	/* Currently we don't support set crypto info more than one time */
-	if (TLS_CRYPTO_INFO_READY(crypto_info))
-		return -EBUSY;
+	if (TLS_CRYPTO_INFO_READY(crypto_info)) {
+		/* Currently we only support setting crypto info more
+		 * than one time for TLS 1.3
+		 */
+		if (crypto_info->version != TLS_1_3_VERSION)
+			return -EBUSY;
+
+		update = true;
+		old_crypto_info = crypto_info;
+		crypto_info = &tmp.info;
+		crypto_ctx = &tmp;
+	}
 
 	rc = copy_from_sockptr(crypto_info, optval, sizeof(*crypto_info));
 	if (rc) {
@@ -643,7 +655,14 @@  static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 		goto err_crypto_info;
 	}
 
-	rc = validate_crypto_info(crypto_info, alt_crypto_info);
+	if (update) {
+		/* Ensure that TLS version and ciphers are not modified */
+		if (crypto_info->version != old_crypto_info->version ||
+		    crypto_info->cipher_type != old_crypto_info->cipher_type)
+			rc = -EINVAL;
+	} else {
+		rc = validate_crypto_info(crypto_info, alt_crypto_info);
+	}
 	if (rc)
 		goto err_crypto_info;
 
@@ -673,7 +692,8 @@  static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSTXDEVICE);
 			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRTXDEVICE);
 		} else {
-			rc = tls_set_sw_offload(sk, 1);
+			rc = tls_set_sw_offload(sk, 1,
+						update ? crypto_info : NULL);
 			if (rc)
 				goto err_crypto_info;
 			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSTXSW);
@@ -687,14 +707,16 @@  static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXDEVICE);
 			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRRXDEVICE);
 		} else {
-			rc = tls_set_sw_offload(sk, 0);
+			rc = tls_set_sw_offload(sk, 0,
+						update ? crypto_info : NULL);
 			if (rc)
 				goto err_crypto_info;
 			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXSW);
 			TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSCURRRXSW);
 			conf = TLS_SW;
 		}
-		tls_sw_strparser_arm(sk, ctx);
+		if (!update)
+			tls_sw_strparser_arm(sk, ctx);
 	}
 
 	if (tx)
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 3dcf8ee60fea..9e5aff5bab98 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -2716,12 +2716,22 @@  int init_prot_info(struct tls_prot_info *prot,
 	return 0;
 }
 
-int tls_set_sw_offload(struct sock *sk, int tx)
+static void tls_finish_key_update(struct sock *sk, struct tls_context *tls_ctx)
 {
+	struct tls_sw_context_rx *ctx = tls_ctx->priv_ctx_rx;
+
+	WRITE_ONCE(ctx->key_update_pending, false);
+	/* wake-up pre-existing poll() */
+	ctx->saved_data_ready(sk);
+}
+
+int tls_set_sw_offload(struct sock *sk, int tx,
+		       struct tls_crypto_info *new_crypto_info)
+{
+	struct tls_crypto_info *crypto_info, *src_crypto_info;
 	struct tls_sw_context_tx *sw_ctx_tx = NULL;
 	struct tls_sw_context_rx *sw_ctx_rx = NULL;
 	const struct tls_cipher_desc *cipher_desc;
-	struct tls_crypto_info *crypto_info;
 	char *iv, *rec_seq, *key, *salt;
 	struct cipher_context *cctx;
 	struct tls_prot_info *prot;
@@ -2733,45 +2743,47 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 	ctx = tls_get_ctx(sk);
 	prot = &ctx->prot_info;
 
-	if (tx) {
-		ctx->priv_ctx_tx = init_ctx_tx(ctx, sk);
-		if (!ctx->priv_ctx_tx)
-			return -ENOMEM;
+	/* new_crypto_info != NULL means rekey */
+	if (!new_crypto_info) {
+		if (tx) {
+			ctx->priv_ctx_tx = init_ctx_tx(ctx, sk);
+			if (!ctx->priv_ctx_tx)
+				return -ENOMEM;
+		} else {
+			ctx->priv_ctx_rx = init_ctx_rx(ctx);
+			if (!ctx->priv_ctx_rx)
+				return -ENOMEM;
+		}
+	}
 
+	if (tx) {
 		sw_ctx_tx = ctx->priv_ctx_tx;
 		crypto_info = &ctx->crypto_send.info;
 		cctx = &ctx->tx;
 		aead = &sw_ctx_tx->aead_send;
 	} else {
-		ctx->priv_ctx_rx = init_ctx_rx(ctx);
-		if (!ctx->priv_ctx_rx)
-			return -ENOMEM;
-
 		sw_ctx_rx = ctx->priv_ctx_rx;
 		crypto_info = &ctx->crypto_recv.info;
 		cctx = &ctx->rx;
 		aead = &sw_ctx_rx->aead_recv;
-		sw_ctx_rx->key_update_pending = false;
 	}
 
-	cipher_desc = get_cipher_desc(crypto_info->cipher_type);
+	src_crypto_info = new_crypto_info ?: crypto_info;
+
+	cipher_desc = get_cipher_desc(src_crypto_info->cipher_type);
 	if (!cipher_desc) {
 		rc = -EINVAL;
 		goto free_priv;
 	}
 
-	rc = init_prot_info(prot, crypto_info, cipher_desc);
+	rc = init_prot_info(prot, src_crypto_info, cipher_desc);
 	if (rc)
 		goto free_priv;
 
-	iv = crypto_info_iv(crypto_info, cipher_desc);
-	key = crypto_info_key(crypto_info, cipher_desc);
-	salt = crypto_info_salt(crypto_info, cipher_desc);
-	rec_seq = crypto_info_rec_seq(crypto_info, cipher_desc);
-
-	memcpy(cctx->iv, salt, cipher_desc->salt);
-	memcpy(cctx->iv + cipher_desc->salt, iv, cipher_desc->iv);
-	memcpy(cctx->rec_seq, rec_seq, cipher_desc->rec_seq);
+	iv = crypto_info_iv(src_crypto_info, cipher_desc);
+	key = crypto_info_key(src_crypto_info, cipher_desc);
+	salt = crypto_info_salt(src_crypto_info, cipher_desc);
+	rec_seq = crypto_info_rec_seq(src_crypto_info, cipher_desc);
 
 	if (!*aead) {
 		*aead = crypto_alloc_aead(cipher_desc->cipher_name, 0, 0);
@@ -2784,20 +2796,30 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 
 	ctx->push_pending_record = tls_sw_push_pending_record;
 
+	/* setkey is the last operation that could fail during a
+	 * rekey. if it succeeds, we can start modifying the
+	 * context.
+	 */
 	rc = crypto_aead_setkey(*aead, key, cipher_desc->key);
-	if (rc)
-		goto free_aead;
+	if (rc) {
+		if (new_crypto_info)
+			goto out;
+		else
+			goto free_aead;
+	}
 
-	rc = crypto_aead_setauthsize(*aead, prot->tag_size);
-	if (rc)
-		goto free_aead;
+	if (!new_crypto_info) {
+		rc = crypto_aead_setauthsize(*aead, prot->tag_size);
+		if (rc)
+			goto free_aead;
+	}
 
-	if (sw_ctx_rx) {
+	if (!tx && !new_crypto_info) {
 		tfm = crypto_aead_tfm(sw_ctx_rx->aead_recv);
 
 		tls_update_rx_zc_capable(ctx);
 		sw_ctx_rx->async_capable =
-			crypto_info->version != TLS_1_3_VERSION &&
+			src_crypto_info->version != TLS_1_3_VERSION &&
 			!!(tfm->__crt_alg->cra_flags & CRYPTO_ALG_ASYNC);
 
 		rc = tls_strp_init(&sw_ctx_rx->strp, sk);
@@ -2805,18 +2827,33 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 			goto free_aead;
 	}
 
+	memcpy(cctx->iv, salt, cipher_desc->salt);
+	memcpy(cctx->iv + cipher_desc->salt, iv, cipher_desc->iv);
+	memcpy(cctx->rec_seq, rec_seq, cipher_desc->rec_seq);
+
+	if (new_crypto_info) {
+		unsafe_memcpy(crypto_info, new_crypto_info,
+			      cipher_desc->crypto_info,
+			      /* size was checked in do_tls_setsockopt_conf */);
+		memzero_explicit(new_crypto_info, cipher_desc->crypto_info);
+		if (!tx)
+			tls_finish_key_update(sk, ctx);
+	}
+
 	goto out;
 
 free_aead:
 	crypto_free_aead(*aead);
 	*aead = NULL;
 free_priv:
-	if (tx) {
-		kfree(ctx->priv_ctx_tx);
-		ctx->priv_ctx_tx = NULL;
-	} else {
-		kfree(ctx->priv_ctx_rx);
-		ctx->priv_ctx_rx = NULL;
+	if (!new_crypto_info) {
+		if (tx) {
+			kfree(ctx->priv_ctx_tx);
+			ctx->priv_ctx_tx = NULL;
+		} else {
+			kfree(ctx->priv_ctx_rx);
+			ctx->priv_ctx_rx = NULL;
+		}
 	}
 out:
 	return rc;