/*
 * Copyright (c) 2016-2017, Mellanox Technologies. All rights reserved.
 * Copyright (c) 2016-2017, Dave Watson <davejwatson@fb.com>. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#ifndef _TLS_OFFLOAD_H
#define _TLS_OFFLOAD_H

#include <linux/types.h>
#include <asm/byteorder.h>
#include <linux/crypto.h>
#include <linux/socket.h>
#include <linux/tcp.h>
#include <linux/mutex.h>
#include <linux/netdevice.h>
#include <linux/rcupdate.h>

#include <net/net_namespace.h>
#include <net/tcp.h>
#include <net/strparser.h>
#include <crypto/aead.h>
#include <uapi/linux/tls.h>

struct tls_rec;

/* Maximum data size carried in a TLS record */
#define TLS_MAX_PAYLOAD_SIZE		((size_t)1 << 14)
/* Minimum record size limit as per RFC8449 */
#define TLS_MIN_RECORD_SIZE_LIM		((size_t)1 << 6)

#define TLS_HEADER_SIZE			5
#define TLS_NONCE_OFFSET		TLS_HEADER_SIZE

#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 TLS_MAX_IV_SIZE			16
#define TLS_MAX_SALT_SIZE		4
#define TLS_TAG_SIZE			16
#define TLS_MAX_REC_SEQ_SIZE		8
#define TLS_MAX_AAD_SIZE		TLS_AAD_SPACE_SIZE

/* For CCM mode, the full 16-bytes of IV is made of '4' fields of given sizes.
 *
 * IV[16] = b0[1] || implicit nonce[4] || explicit nonce[8] || length[3]
 *
 * The field 'length' is encoded in field 'b0' as '(length width - 1)'.
 * Hence b0 contains (3 - 1) = 2.
 */
#define TLS_AES_CCM_IV_B0_BYTE		2
#define TLS_SM4_CCM_IV_B0_BYTE		2

enum {
	TLS_BASE,
	TLS_SW,
	TLS_HW,
	TLS_NUM_CONFIG,
};

struct tx_work {
	struct delayed_work work;
	struct sock *sk;
};

struct tls_sw_context_tx {
	struct crypto_aead *aead_send;
	struct crypto_wait async_wait;
	struct tx_work tx_work;
	struct tls_rec *open_rec;
	struct list_head tx_list;
	atomic_t encrypt_pending;
	u8 async_capable:1;

#define BIT_TX_SCHEDULED	0
#define BIT_TX_CLOSING		1
	unsigned long tx_bitmask;
};

struct tls_strparser {
	struct sock *sk;

	/* Bitfield word and msg_ready are serialized by the lower
	 * socket lock; BH and worker contexts both acquire it.
	 */
	u32 mark : 8;
	u32 stopped : 1;
	u32 copy_mode : 1;
	u32 mixed_decrypted : 1;

	u32 msg_announced : 1;

	bool msg_ready;

	struct strp_msg stm;

	struct sk_buff *anchor;
	struct work_struct work;
};

struct tls_sw_context_rx {
	struct crypto_aead *aead_recv;
	struct crypto_wait async_wait;
	struct sk_buff_head rx_list;	/* list of decrypted 'data' records */
	void (*saved_data_ready)(struct sock *sk);

	u8 reader_present;
	u8 async_capable:1;
	u8 zc_capable:1;
	u8 reader_contended:1;
	bool key_update_pending;

	struct tls_strparser strp;

	atomic_t decrypt_pending;
	struct sk_buff_head async_hold;
	struct wait_queue_head wq;
};

struct tls_record_info {
	struct list_head list;
	u32 end_seq;
	int len;
	int num_frags;
	skb_frag_t frags[MAX_SKB_FRAGS];
};

#define TLS_DRIVER_STATE_SIZE_TX	16
struct tls_offload_context_tx {
	struct crypto_aead *aead_send;
	spinlock_t lock;	/* protects records list */
	struct list_head records_list;
	struct tls_record_info *open_record;
	struct tls_record_info *retransmit_hint;
	u64 hint_record_sn;
	u64 unacked_record_sn;

	struct scatterlist sg_tx_data[MAX_SKB_FRAGS];
	void (*sk_destruct)(struct sock *sk);
	struct work_struct destruct_work;
	struct tls_context *ctx;
	/* The TLS layer reserves room for driver specific state
	 * Currently the belief is that there is not enough
	 * driver specific state to justify another layer of indirection
	 */
	u8 driver_state[TLS_DRIVER_STATE_SIZE_TX] __aligned(8);
};

enum tls_context_flags {
	/* tls_device_down was called after the netdev went down, device state
	 * was released, and kTLS works in software, even though rx_conf is
	 * still TLS_HW (needed for transition).
	 */
	TLS_RX_DEV_DEGRADED = 0,
	/* Unlike RX where resync is driven entirely by the core in TX only
	 * the driver knows when things went out of sync, so we need the flag
	 * to be atomic.
	 */
	TLS_TX_SYNC_SCHED = 1,
	/* tls_dev_del was called for the RX side, device state was released,
	 * but tls_ctx->netdev might still be kept, because TX-side driver
	 * resources might not be released yet. Used to prevent the second
	 * tls_dev_del call in tls_device_down if it happens simultaneously.
	 */
	TLS_RX_DEV_CLOSED = 2,
};

struct cipher_context {
	char iv[TLS_MAX_IV_SIZE + TLS_MAX_SALT_SIZE];
	char rec_seq[TLS_MAX_REC_SEQ_SIZE];
};

union tls_crypto_context {
	struct tls_crypto_info info;
	union {
		struct tls12_crypto_info_aes_gcm_128 aes_gcm_128;
		struct tls12_crypto_info_aes_gcm_256 aes_gcm_256;
		struct tls12_crypto_info_chacha20_poly1305 chacha20_poly1305;
		struct tls12_crypto_info_sm4_gcm sm4_gcm;
		struct tls12_crypto_info_sm4_ccm sm4_ccm;
	};
};

struct tls_prot_info {
	u16 version;
	u16 cipher_type;
	u16 prepend_size;
	u16 tag_size;
	u16 overhead_size;
	u16 iv_size;
	u16 salt_size;
	u16 rec_seq_size;
	u16 aad_size;
	u16 tail_size;
};

struct tls_context {
	/* read-only cache line */
	struct tls_prot_info prot_info;

	u8 tx_conf:3;
	u8 rx_conf:3;
	u8 zerocopy_sendfile:1;
	u8 rx_no_pad:1;
	u16 tx_max_payload_len;

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

	void *priv_ctx_tx;
	void *priv_ctx_rx;

	struct net_device __rcu *netdev;

	/* rw cache line */
	struct cipher_context tx;
	struct cipher_context rx;

	struct scatterlist *partially_sent_record;
	u16 partially_sent_offset;

	bool splicing_pages;
	bool pending_open_record_frags;

	struct mutex tx_lock; /* protects partially_sent_* fields and
			       * per-type TX fields
			       */
	unsigned long flags;

	/* cache cold stuff */
	struct proto *sk_proto;
	struct sock *sk;

	void (*sk_destruct)(struct sock *sk);

	union tls_crypto_context crypto_send;
	union tls_crypto_context crypto_recv;

	struct list_head list;
	refcount_t refcount;
	struct rcu_head rcu;
};

enum tls_offload_ctx_dir {
	TLS_OFFLOAD_CTX_DIR_RX,
	TLS_OFFLOAD_CTX_DIR_TX,
};

struct tlsdev_ops {
	int (*tls_dev_add)(struct net_device *netdev, struct sock *sk,
			   enum tls_offload_ctx_dir direction,
			   struct tls_crypto_info *crypto_info,
			   u32 start_offload_tcp_sn);
	void (*tls_dev_del)(struct net_device *netdev,
			    struct tls_context *ctx,
			    enum tls_offload_ctx_dir direction);
	int (*tls_dev_resync)(struct net_device *netdev,
			      struct sock *sk, u32 seq, u8 *rcd_sn,
			      enum tls_offload_ctx_dir direction);
};

enum tls_offload_sync_type {
	TLS_OFFLOAD_SYNC_TYPE_DRIVER_REQ = 0,
	TLS_OFFLOAD_SYNC_TYPE_CORE_NEXT_HINT = 1,
	TLS_OFFLOAD_SYNC_TYPE_DRIVER_REQ_ASYNC = 2,
};

#define TLS_DEVICE_RESYNC_NH_START_IVAL		2
#define TLS_DEVICE_RESYNC_NH_MAX_IVAL		128

#define TLS_DEVICE_RESYNC_ASYNC_LOGMAX		13
struct tls_offload_resync_async {
	atomic64_t req;
	u16 loglen;
	u16 rcd_delta;
	u32 log[TLS_DEVICE_RESYNC_ASYNC_LOGMAX];
};

#define TLS_DRIVER_STATE_SIZE_RX	8
struct tls_offload_context_rx {
	/* sw must be the first member of tls_offload_context_rx */
	struct tls_sw_context_rx sw;
	enum tls_offload_sync_type resync_type;
	/* this member is set regardless of resync_type, to avoid branches */
	u8 resync_nh_reset:1;
	/* CORE_NEXT_HINT-only member, but use the hole here */
	u8 resync_nh_do_now:1;
	union {
		/* TLS_OFFLOAD_SYNC_TYPE_DRIVER_REQ */
		struct {
			atomic64_t resync_req;
		};
		/* TLS_OFFLOAD_SYNC_TYPE_CORE_NEXT_HINT */
		struct {
			u32 decrypted_failed;
			u32 decrypted_tgt;
		} resync_nh;
		/* TLS_OFFLOAD_SYNC_TYPE_DRIVER_REQ_ASYNC */
		struct {
			struct tls_offload_resync_async *resync_async;
		};
	};
	/* The TLS layer reserves room for driver specific state
	 * Currently the belief is that there is not enough
	 * driver specific state to justify another layer of indirection
	 */
	u8 driver_state[TLS_DRIVER_STATE_SIZE_RX] __aligned(8);
};

struct tls_record_info *tls_get_record(struct tls_offload_context_tx *context,
				       u32 seq, u64 *p_record_sn);

static inline bool tls_record_is_start_marker(struct tls_record_info *rec)
{
	return rec->len == 0;
}

static inline u32 tls_record_start_seq(struct tls_record_info *rec)
{
	return rec->end_seq - rec->len;
}

struct sk_buff *
tls_validate_xmit_skb(struct sock *sk, struct net_device *dev,
		      struct sk_buff *skb);
struct sk_buff *
tls_validate_xmit_skb_sw(struct sock *sk, struct net_device *dev,
			 struct sk_buff *skb);

static inline bool tls_is_skb_tx_device_offloaded(const struct sk_buff *skb)
{
#ifdef CONFIG_TLS_DEVICE
	struct sock *sk = skb->sk;

	return sk && sk_fullsock(sk) &&
	       (smp_load_acquire(&sk->sk_validate_xmit_skb) ==
	       &tls_validate_xmit_skb);
#else
	return false;
#endif
}

static inline struct tls_context *tls_get_ctx(const struct sock *sk)
{
	const struct inet_connection_sock *icsk = inet_csk(sk);

	/* Use RCU on icsk_ulp_data only for sock diag code,
	 * TLS data path doesn't need rcu_dereference().
	 */
	return (__force void *)icsk->icsk_ulp_data;
}

static inline struct tls_sw_context_rx *tls_sw_ctx_rx(
		const struct tls_context *tls_ctx)
{
	return (struct tls_sw_context_rx *)tls_ctx->priv_ctx_rx;
}

static inline struct tls_sw_context_tx *tls_sw_ctx_tx(
		const struct tls_context *tls_ctx)
{
	return (struct tls_sw_context_tx *)tls_ctx->priv_ctx_tx;
}

static inline struct tls_offload_context_tx *
tls_offload_ctx_tx(const struct tls_context *tls_ctx)
{
	return (struct tls_offload_context_tx *)tls_ctx->priv_ctx_tx;
}

static inline bool tls_sw_has_ctx_tx(const struct sock *sk)
{
	struct tls_context *ctx;

	if (!sk_is_inet(sk) || !inet_test_bit(IS_ICSK, sk))
		return false;

	ctx = tls_get_ctx(sk);
	if (!ctx)
		return false;
	return !!tls_sw_ctx_tx(ctx);
}

static inline bool tls_sw_has_ctx_rx(const struct sock *sk)
{
	struct tls_context *ctx;

	if (!sk_is_inet(sk) || !inet_test_bit(IS_ICSK, sk))
		return false;

	ctx = tls_get_ctx(sk);
	if (!ctx)
		return false;
	return !!tls_sw_ctx_rx(ctx);
}

static inline struct tls_offload_context_rx *
tls_offload_ctx_rx(const struct tls_context *tls_ctx)
{
	return (struct tls_offload_context_rx *)tls_ctx->priv_ctx_rx;
}

static inline void *__tls_driver_ctx(struct tls_context *tls_ctx,
				     enum tls_offload_ctx_dir direction)
{
	if (direction == TLS_OFFLOAD_CTX_DIR_TX)
		return tls_offload_ctx_tx(tls_ctx)->driver_state;
	else
		return tls_offload_ctx_rx(tls_ctx)->driver_state;
}

static inline void *
tls_driver_ctx(const struct sock *sk, enum tls_offload_ctx_dir direction)
{
	return __tls_driver_ctx(tls_get_ctx(sk), direction);
}

#define RESYNC_REQ BIT(0)
#define RESYNC_REQ_ASYNC BIT(1)
/* The TLS context is valid until sk_destruct is called */
static inline void tls_offload_rx_resync_request(struct sock *sk, __be32 seq)
{
	struct tls_context *tls_ctx = tls_get_ctx(sk);
	struct tls_offload_context_rx *rx_ctx = tls_offload_ctx_rx(tls_ctx);

	atomic64_set(&rx_ctx->resync_req, ((u64)ntohl(seq) << 32) | RESYNC_REQ);
}

/* Log all TLS record header TCP sequences in [seq, seq+len] */
static inline void
tls_offload_rx_resync_async_request_start(struct tls_offload_resync_async *resync_async,
					  __be32 seq, u16 len)
{
	atomic64_set(&resync_async->req, ((u64)ntohl(seq) << 32) |
		     ((u64)len << 16) | RESYNC_REQ | RESYNC_REQ_ASYNC);
	resync_async->loglen = 0;
	resync_async->rcd_delta = 0;
}

static inline void
tls_offload_rx_resync_async_request_end(struct tls_offload_resync_async *resync_async,
					__be32 seq)
{
	atomic64_set(&resync_async->req, ((u64)ntohl(seq) << 32) | RESYNC_REQ);
}

static inline void
tls_offload_rx_resync_async_request_cancel(struct tls_offload_resync_async *resync_async)
{
	atomic64_set(&resync_async->req, 0);
}

static inline void
tls_offload_rx_resync_set_type(struct sock *sk, enum tls_offload_sync_type type)
{
	struct tls_context *tls_ctx = tls_get_ctx(sk);

	tls_offload_ctx_rx(tls_ctx)->resync_type = type;
}

/* Driver's seq tracking has to be disabled until resync succeeded */
static inline bool tls_offload_tx_resync_pending(struct sock *sk)
{
	struct tls_context *tls_ctx = tls_get_ctx(sk);
	bool ret;

	ret = test_bit(TLS_TX_SYNC_SCHED, &tls_ctx->flags);
	smp_mb__after_atomic();
	return ret;
}

struct sk_buff *tls_encrypt_skb(struct sk_buff *skb);

#ifdef CONFIG_TLS_DEVICE
void tls_device_sk_destruct(struct sock *sk);
void tls_offload_tx_resync_request(struct sock *sk, u32 got_seq, u32 exp_seq);

static inline bool tls_is_sk_rx_device_offloaded(struct sock *sk)
{
	if (!sk_fullsock(sk) ||
	    smp_load_acquire(&sk->sk_destruct) != tls_device_sk_destruct)
		return false;
	return tls_get_ctx(sk)->rx_conf == TLS_HW;
}
#endif
#endif /* _TLS_OFFLOAD_H */