diff mbox series

[net-next,v2,3/5] tls: implement rekey for TLS1.3

Message ID c7e5a34fcc3759326a89713a392a807f3a5069a0.1676052788.git.sd@queasysnail.net (mailing list archive)
State New
Headers show
Series tls: implement key updates for TLS1.3 | expand

Commit Message

Sabrina Dubroca Feb. 14, 2023, 11:17 a.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.

v2: reverse xmas tree
    turn the alt_crypto_info into an else if
    don't modify the context when rekey fails

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
---
 net/tls/tls.h        |   3 +-
 net/tls/tls_device.c |   2 +-
 net/tls/tls_main.c   |  37 +++++++++---
 net/tls/tls_sw.c     | 134 +++++++++++++++++++++++++++++++------------
 4 files changed, 129 insertions(+), 47 deletions(-)
diff mbox series

Patch

diff --git a/net/tls/tls.h b/net/tls/tls.h
index 34d0fe814600..6f9c85eaa9c5 100644
--- a/net/tls/tls.h
+++ b/net/tls/tls.h
@@ -90,7 +90,8 @@  int tls_sk_attach(struct sock *sk, int optname, char __user *optval,
 		  unsigned int optlen);
 void tls_err_abort(struct sock *sk, int err);
 
-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 c149f36b42ee..1ad50c253dfe 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -1291,7 +1291,7 @@  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 fb1da1780f50..24a4bdb54a53 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -669,9 +669,11 @@  static int tls_getsockopt(struct sock *sk, int level, int optname,
 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);
+	union tls_crypto_context tmp = {};
+	bool update = false;
 	size_t optsize;
 	int rc = 0;
 	int conf;
@@ -687,9 +689,17 @@  static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 		alt_crypto_info = &ctx->crypto_send.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;
+	}
 
 	rc = copy_from_sockptr(crypto_info, optval, sizeof(*crypto_info));
 	if (rc) {
@@ -704,8 +714,15 @@  static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 		goto err_crypto_info;
 	}
 
-	/* Ensure that TLS version and ciphers are same in both directions */
-	if (TLS_CRYPTO_INFO_READY(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;
+			goto err_crypto_info;
+		}
+	} else if (TLS_CRYPTO_INFO_READY(alt_crypto_info)) {
+		/* Ensure that TLS version and ciphers are same in both directions */
 		if (alt_crypto_info->version != crypto_info->version ||
 		    alt_crypto_info->cipher_type != crypto_info->cipher_type) {
 			rc = -EINVAL;
@@ -772,7 +789,8 @@  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);
@@ -786,7 +804,8 @@  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);
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 149a39d9a56a..a35b3bfe5b47 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -2508,23 +2508,50 @@  void tls_update_rx_zc_capable(struct tls_context *tls_ctx)
 		tls_ctx->prot_info.version != TLS_1_3_VERSION;
 }
 
-int tls_set_sw_offload(struct sock *sk, int tx)
+static void tls_finish_key_update(struct tls_context *tls_ctx)
+{
+	struct tls_sw_context_rx *ctx = tls_ctx->priv_ctx_rx;
+
+	ctx->key_update_pending = false;
+}
+
+int tls_set_sw_offload(struct sock *sk, int tx,
+		       struct tls_crypto_info *new_crypto_info)
 {
 	u16 nonce_size, tag_size, iv_size, rec_seq_size, salt_size;
+	struct tls_crypto_info *crypto_info, *src_crypto_info;
 	char *iv, *rec_seq, *key, *salt, *cipher_name;
 	struct tls_sw_context_tx *sw_ctx_tx = NULL;
 	struct tls_sw_context_rx *sw_ctx_rx = NULL;
 	struct tls_context *ctx = tls_get_ctx(sk);
-	struct tls_crypto_info *crypto_info;
+	size_t keysize, crypto_info_size;
 	struct cipher_context *cctx;
 	struct tls_prot_info *prot;
 	struct crypto_aead **aead;
 	struct crypto_tfm *tfm;
-	size_t keysize;
 	int rc = 0;
 
 	prot = &ctx->prot_info;
 
+	if (new_crypto_info) {
+		/* non-NULL new_crypto_info means rekey */
+		src_crypto_info = new_crypto_info;
+		if (tx) {
+			sw_ctx_tx = ctx->priv_ctx_tx;
+			crypto_info = &ctx->crypto_send.info;
+			cctx = &ctx->tx;
+			aead = &sw_ctx_tx->aead_send;
+			sw_ctx_tx = NULL;
+		} else {
+			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 = NULL;
+		}
+		goto skip_init;
+	}
+
 	if (tx) {
 		if (!ctx->priv_ctx_tx) {
 			sw_ctx_tx = kzalloc(sizeof(*sw_ctx_tx), GFP_KERNEL);
@@ -2571,12 +2598,15 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 		aead = &sw_ctx_rx->aead_recv;
 		sw_ctx_rx->key_update_pending = false;
 	}
+	src_crypto_info = crypto_info;
 
+skip_init:
 	switch (crypto_info->cipher_type) {
 	case TLS_CIPHER_AES_GCM_128: {
 		struct tls12_crypto_info_aes_gcm_128 *gcm_128_info;
 
-		gcm_128_info = (void *)crypto_info;
+		crypto_info_size = sizeof(struct tls12_crypto_info_aes_gcm_128);
+		gcm_128_info = (void *)src_crypto_info;
 		nonce_size = TLS_CIPHER_AES_GCM_128_IV_SIZE;
 		tag_size = TLS_CIPHER_AES_GCM_128_TAG_SIZE;
 		iv_size = TLS_CIPHER_AES_GCM_128_IV_SIZE;
@@ -2593,7 +2623,8 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 	case TLS_CIPHER_AES_GCM_256: {
 		struct tls12_crypto_info_aes_gcm_256 *gcm_256_info;
 
-		gcm_256_info = (void *)crypto_info;
+		crypto_info_size = sizeof(struct tls12_crypto_info_aes_gcm_256);
+		gcm_256_info = (void *)src_crypto_info;
 		nonce_size = TLS_CIPHER_AES_GCM_256_IV_SIZE;
 		tag_size = TLS_CIPHER_AES_GCM_256_TAG_SIZE;
 		iv_size = TLS_CIPHER_AES_GCM_256_IV_SIZE;
@@ -2610,7 +2641,8 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 	case TLS_CIPHER_AES_CCM_128: {
 		struct tls12_crypto_info_aes_ccm_128 *ccm_128_info;
 
-		ccm_128_info = (void *)crypto_info;
+		crypto_info_size = sizeof(struct tls12_crypto_info_aes_ccm_128);
+		ccm_128_info = (void *)src_crypto_info;
 		nonce_size = TLS_CIPHER_AES_CCM_128_IV_SIZE;
 		tag_size = TLS_CIPHER_AES_CCM_128_TAG_SIZE;
 		iv_size = TLS_CIPHER_AES_CCM_128_IV_SIZE;
@@ -2627,7 +2659,8 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 	case TLS_CIPHER_CHACHA20_POLY1305: {
 		struct tls12_crypto_info_chacha20_poly1305 *chacha20_poly1305_info;
 
-		chacha20_poly1305_info = (void *)crypto_info;
+		crypto_info_size = sizeof(struct tls12_crypto_info_chacha20_poly1305);
+		chacha20_poly1305_info = (void *)src_crypto_info;
 		nonce_size = 0;
 		tag_size = TLS_CIPHER_CHACHA20_POLY1305_TAG_SIZE;
 		iv_size = TLS_CIPHER_CHACHA20_POLY1305_IV_SIZE;
@@ -2644,7 +2677,8 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 	case TLS_CIPHER_SM4_GCM: {
 		struct tls12_crypto_info_sm4_gcm *sm4_gcm_info;
 
-		sm4_gcm_info = (void *)crypto_info;
+		crypto_info_size = sizeof(struct tls12_crypto_info_sm4_gcm);
+		sm4_gcm_info = (void *)src_crypto_info;
 		nonce_size = TLS_CIPHER_SM4_GCM_IV_SIZE;
 		tag_size = TLS_CIPHER_SM4_GCM_TAG_SIZE;
 		iv_size = TLS_CIPHER_SM4_GCM_IV_SIZE;
@@ -2661,7 +2695,8 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 	case TLS_CIPHER_SM4_CCM: {
 		struct tls12_crypto_info_sm4_ccm *sm4_ccm_info;
 
-		sm4_ccm_info = (void *)crypto_info;
+		crypto_info_size = sizeof(struct tls12_crypto_info_sm4_ccm);
+		sm4_ccm_info = (void *)src_crypto_info;
 		nonce_size = TLS_CIPHER_SM4_CCM_IV_SIZE;
 		tag_size = TLS_CIPHER_SM4_CCM_TAG_SIZE;
 		iv_size = TLS_CIPHER_SM4_CCM_IV_SIZE;
@@ -2678,7 +2713,8 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 	case TLS_CIPHER_ARIA_GCM_128: {
 		struct tls12_crypto_info_aria_gcm_128 *aria_gcm_128_info;
 
-		aria_gcm_128_info = (void *)crypto_info;
+		crypto_info_size = sizeof(struct tls12_crypto_info_aria_gcm_128);
+		aria_gcm_128_info = (void *)src_crypto_info;
 		nonce_size = TLS_CIPHER_ARIA_GCM_128_IV_SIZE;
 		tag_size = TLS_CIPHER_ARIA_GCM_128_TAG_SIZE;
 		iv_size = TLS_CIPHER_ARIA_GCM_128_IV_SIZE;
@@ -2695,7 +2731,8 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 	case TLS_CIPHER_ARIA_GCM_256: {
 		struct tls12_crypto_info_aria_gcm_256 *gcm_256_info;
 
-		gcm_256_info = (void *)crypto_info;
+		crypto_info_size = sizeof(struct tls12_crypto_info_aria_gcm_256);
+		gcm_256_info = (void *)src_crypto_info;
 		nonce_size = TLS_CIPHER_ARIA_GCM_256_IV_SIZE;
 		tag_size = TLS_CIPHER_ARIA_GCM_256_TAG_SIZE;
 		iv_size = TLS_CIPHER_ARIA_GCM_256_IV_SIZE;
@@ -2739,19 +2776,18 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 			      prot->tag_size + prot->tail_size;
 	prot->iv_size = iv_size;
 	prot->salt_size = salt_size;
-	cctx->iv = kmalloc(iv_size + salt_size, GFP_KERNEL);
-	if (!cctx->iv) {
-		rc = -ENOMEM;
-		goto free_priv;
-	}
-	/* Note: 128 & 256 bit salt are the same size */
-	prot->rec_seq_size = rec_seq_size;
-	memcpy(cctx->iv, salt, salt_size);
-	memcpy(cctx->iv + salt_size, iv, iv_size);
-	cctx->rec_seq = kmemdup(rec_seq, rec_seq_size, GFP_KERNEL);
-	if (!cctx->rec_seq) {
-		rc = -ENOMEM;
-		goto free_iv;
+	if (!new_crypto_info) {
+		cctx->iv = kmalloc(iv_size + salt_size, GFP_KERNEL);
+		if (!cctx->iv) {
+			rc = -ENOMEM;
+			goto free_priv;
+		}
+
+		cctx->rec_seq = kmemdup(rec_seq, rec_seq_size, GFP_KERNEL);
+		if (!cctx->rec_seq) {
+			rc = -ENOMEM;
+			goto free_iv;
+		}
 	}
 
 	if (!*aead) {
@@ -2765,14 +2801,24 @@  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, keysize);
+	if (rc) {
+		if (new_crypto_info)
+			goto out;
+		else
+			goto free_aead;
+	}
 
-	if (rc)
-		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) {
 		tfm = crypto_aead_tfm(sw_ctx_rx->aead_recv);
@@ -2787,6 +2833,20 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 			goto free_aead;
 	}
 
+	/* Note: 128 & 256 bit salt are the same size */
+	prot->rec_seq_size = rec_seq_size;
+	memcpy(cctx->iv, salt, salt_size);
+	memcpy(cctx->iv + salt_size, iv, iv_size);
+
+	if (new_crypto_info) {
+		memcpy(cctx->rec_seq, rec_seq, rec_seq_size);
+
+		memcpy(crypto_info, new_crypto_info, crypto_info_size);
+		memzero_explicit(new_crypto_info, crypto_info_size);
+		if (!tx)
+			tls_finish_key_update(ctx);
+	}
+
 	goto out;
 
 free_aead:
@@ -2799,12 +2859,14 @@  int tls_set_sw_offload(struct sock *sk, int tx)
 	kfree(cctx->iv);
 	cctx->iv = 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;