Commit 88527790 authored by Jakub Kicinski's avatar Jakub Kicinski Committed by David S. Miller
Browse files

tls: rx: add sockopt for enabling optimistic decrypt with TLS 1.3 



Since optimisitic decrypt may add extra load in case of retries
require socket owner to explicitly opt-in.

Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ce61327c

Documentation/networking/tls.rst

+18 −0
Original line number Diff line number Diff line
@@ -239,6 +239,19 @@ for the original TCP transmission and TCP retransmissions. To the receiver 
this will look like TLS records had been tampered with and will result

in record authentication failures.



TLS_RX_EXPECT_NO_PAD

~~~~~~~~~~~~~~~~~~~~



TLS 1.3 only. Expect the sender to not pad records. This allows the data

to be decrypted directly into user space buffers with TLS 1.3.



This optimization is safe to enable only if the remote end is trusted,

otherwise it is an attack vector to doubling the TLS processing cost.



If the record decrypted turns out to had been padded or is not a data

record it will be decrypted again into a kernel buffer without zero copy.

Such events are counted in the ``TlsDecryptRetry`` statistic.



Statistics

==========
@@ -264,3 +277,8 @@ TLS implementation exposes the following per-namespace statistics 


- ``TlsDeviceRxResync`` -

  number of RX resyncs sent to NICs handling cryptography



- ``TlsDecryptRetry`` -

  number of RX records which had to be re-decrypted due to

  ``TLS_RX_EXPECT_NO_PAD`` mis-prediction. Note that this counter will

  also increment for non-data records.

include/linux/sockptr.h

+8 −0
Original line number Diff line number Diff line
@@ -102,4 +102,12 @@ static inline long strncpy_from_sockptr(char *dst, sockptr_t src, size_t count) 
	return strncpy_from_user(dst, src.user, count);

}



static inline int check_zeroed_sockptr(sockptr_t src, size_t offset,

				       size_t size)

{

	if (!sockptr_is_kernel(src))

		return check_zeroed_user(src.user + offset, size);

	return memchr_inv(src.kernel + offset, 0, size) == NULL;

}



#endif /* _LINUX_SOCKPTR_H */

include/net/tls.h

+3 −0
Original line number Diff line number Diff line
@@ -149,6 +149,7 @@ struct tls_sw_context_rx { 


	struct sk_buff *recv_pkt;

	u8 async_capable:1;

	u8 zc_capable:1;

	atomic_t decrypt_pending;

	/* protect crypto_wait with decrypt_pending*/

	spinlock_t decrypt_compl_lock;
@@ -239,6 +240,7 @@ struct tls_context { 
	u8 tx_conf:3;

	u8 rx_conf:3;

	u8 zerocopy_sendfile:1;

	u8 rx_no_pad:1;



	int (*push_pending_record)(struct sock *sk, int flags);

	void (*sk_write_space)(struct sock *sk);
@@ -358,6 +360,7 @@ int tls_sk_attach(struct sock *sk, int optname, char __user *optval, 
void tls_err_abort(struct sock *sk, int err);



int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx);

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);

int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);

include/uapi/linux/snmp.h

+1 −0
Original line number Diff line number Diff line
@@ -344,6 +344,7 @@ enum 
	LINUX_MIB_TLSRXDEVICE,			/* TlsRxDevice */

	LINUX_MIB_TLSDECRYPTERROR,		/* TlsDecryptError */

	LINUX_MIB_TLSRXDEVICERESYNC,		/* TlsRxDeviceResync */

	LINUX_MIN_TLSDECRYPTRETRY,		/* TlsDecryptRetry */

	__LINUX_MIB_TLSMAX

};

include/uapi/linux/tls.h

+2 −0
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ 
#define TLS_TX			1	/* Set transmit parameters */

#define TLS_RX			2	/* Set receive parameters */

#define TLS_TX_ZEROCOPY_RO	3	/* TX zerocopy (only sendfile now) */

#define TLS_RX_EXPECT_NO_PAD	4	/* Attempt opportunistic zero-copy */



/* Supported versions */

#define TLS_VERSION_MINOR(ver)	((ver) & 0xFF)
@@ -162,6 +163,7 @@ enum { 
	TLS_INFO_TXCONF,

	TLS_INFO_RXCONF,

	TLS_INFO_ZC_RO_TX,

	TLS_INFO_RX_NO_PAD,

	__TLS_INFO_MAX,

};

#define TLS_INFO_MAX (__TLS_INFO_MAX - 1)