/*
 * 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/skmsg.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>


/* Maximum data size carried in a TLS record */
#define TLS_MAX_PAYLOAD_SIZE            ((size_t)1 << 14)

#define TLS_HEADER_SIZE                 5
#define TLS_NONCE_OFFSET                TLS_HEADER_SIZE

#define TLS_CRYPTO_INFO_READY(info)     ((info)->cipher_type)

#define TLS_RECORD_TYPE_DATA            0x17

#define TLS_AAD_SPACE_SIZE              13

#define MAX_IV_SIZE                     16
#define TLS_MAX_REC_SEQ_SIZE            8

/* For AES-CCM, 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_INC_STATS(net, field)                             \
        __SNMP_INC_STATS((net)->mib.tls_statistics, field)
#define TLS_INC_STATS(net, field)                               \
        SNMP_INC_STATS((net)->mib.tls_statistics, field)
#define __TLS_DEC_STATS(net, field)                             \
        __SNMP_DEC_STATS((net)->mib.tls_statistics, field)
#define TLS_DEC_STATS(net, field)                               \
        SNMP_DEC_STATS((net)->mib.tls_statistics, field)

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

/* TLS records are maintained in 'struct tls_rec'. It stores the memory pages
 * allocated or mapped for each TLS record. After encryption, the records are
 * stores in a linked list.
 */
struct tls_rec {
        struct list_head list;
        int tx_ready;
        int tx_flags;

        struct sk_msg msg_plaintext;
        struct sk_msg msg_encrypted;

        /* AAD | msg_plaintext.sg.data | sg_tag */
        struct scatterlist sg_aead_in[2];
        /* AAD | msg_encrypted.sg.data (data contains overhead for hdr & iv & tag) */
        struct scatterlist sg_aead_out[2];

        char content_type;
        struct scatterlist sg_content_type;

        char aad_space[TLS_AAD_SPACE_SIZE];
        u8 iv_data[MAX_IV_SIZE];
        struct aead_request aead_req;
        u8 aead_req_ctx[];
};

struct tls_msg {
        struct strp_msg rxm;
        u8 control;
};

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;
        int async_notify;
        u8 async_capable:1;

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

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

        struct sk_buff *recv_pkt;
        u8 control;
        u8 async_capable:1;
        u8 decrypted:1;
        atomic_t decrypt_pending;
        bool async_notify;
};

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

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);
        u8 driver_state[] __aligned(8);
        /* 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
         */
#define TLS_DRIVER_STATE_SIZE_TX        16
};

#define TLS_OFFLOAD_CONTEXT_SIZE_TX                                            \
        (sizeof(struct tls_offload_context_tx) + TLS_DRIVER_STATE_SIZE_TX)

enum tls_context_flags {
        TLS_RX_SYNC_RUNNING = 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,
};

struct cipher_context {
        char *iv;
        char *rec_seq;
};

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 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;

        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 *netdev;

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

        struct scatterlist *partially_sent_record;
        u16 partially_sent_offset;

        bool in_tcp_sendpages;
        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;

        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,
};

#define TLS_DEVICE_RESYNC_NH_START_IVAL         2
#define TLS_DEVICE_RESYNC_NH_MAX_IVAL           128

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;
        };
        u8 driver_state[] __aligned(8);
        /* 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
         */
#define TLS_DRIVER_STATE_SIZE_RX        8
};

#define TLS_OFFLOAD_CONTEXT_SIZE_RX                                     \
        (sizeof(struct tls_offload_context_rx) + TLS_DRIVER_STATE_SIZE_RX)

struct tls_context *tls_ctx_create(struct sock *sk);
void tls_ctx_free(struct sock *sk, struct tls_context *ctx);
void update_sk_prot(struct sock *sk, struct tls_context *ctx);

int wait_on_pending_writer(struct sock *sk, long *timeo);
int tls_sk_query(struct sock *sk, int optname, char __user *optval,
                int __user *optlen);
int tls_sk_attach(struct sock *sk, int optname, char __user *optval,
                  unsigned int optlen);

int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx);
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);
int tls_sw_sendpage_locked(struct sock *sk, struct page *page,
                           int offset, size_t size, int flags);
int tls_sw_sendpage(struct sock *sk, struct page *page,
                    int offset, size_t size, int flags);
void tls_sw_cancel_work_tx(struct tls_context *tls_ctx);
void tls_sw_release_resources_tx(struct sock *sk);
void tls_sw_free_ctx_tx(struct tls_context *tls_ctx);
void tls_sw_free_resources_rx(struct sock *sk);
void tls_sw_release_resources_rx(struct sock *sk);
void tls_sw_free_ctx_rx(struct tls_context *tls_ctx);
int tls_sw_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
                   int nonblock, int flags, int *addr_len);
bool tls_sw_stream_read(const struct sock *sk);
ssize_t tls_sw_splice_read(struct socket *sock, loff_t *ppos,
                           struct pipe_inode_info *pipe,
                           size_t len, unsigned int flags);

int tls_device_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
int tls_device_sendpage(struct sock *sk, struct page *page,
                        int offset, size_t size, int flags);
int tls_tx_records(struct sock *sk, int flags);

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;
}

int tls_push_sg(struct sock *sk, struct tls_context *ctx,
                struct scatterlist *sg, u16 first_offset,
                int flags);
int tls_push_partial_record(struct sock *sk, struct tls_context *ctx,
                            int flags);
void tls_free_partial_record(struct sock *sk, struct tls_context *ctx);

static inline struct tls_msg *tls_msg(struct sk_buff *skb)
{
        return (struct tls_msg *)strp_msg(skb);
}

static inline bool tls_is_partially_sent_record(struct tls_context *ctx)
{
        return !!ctx->partially_sent_record;
}

static inline bool tls_is_pending_open_record(struct tls_context *tls_ctx)
{
        return tls_ctx->pending_open_record_frags;
}

static inline bool is_tx_ready(struct tls_sw_context_tx *ctx)
{
        struct tls_rec *rec;

        rec = list_first_entry(&ctx->tx_list, struct tls_rec, list);
        if (!rec)
                return false;

        return READ_ONCE(rec->tx_ready);
}

static inline u16 tls_user_config(struct tls_context *ctx, bool tx)
{
        u16 config = tx ? ctx->tx_conf : ctx->rx_conf;

        switch (config) {
        case TLS_BASE:
                return TLS_CONF_BASE;
        case TLS_SW:
                return TLS_CONF_SW;
        case TLS_HW:
                return TLS_CONF_HW;
        case TLS_HW_RECORD:
                return TLS_CONF_HW_RECORD;
        }
        return 0;
}

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

static inline bool tls_is_sk_tx_device_offloaded(struct sock *sk)
{
#ifdef CONFIG_SOCK_VALIDATE_XMIT
        return sk_fullsock(sk) &&
               (smp_load_acquire(&sk->sk_validate_xmit_skb) ==
               &tls_validate_xmit_skb);
#else
        return false;
#endif
}

static inline void tls_err_abort(struct sock *sk, int err)
{
        sk->sk_err = err;
        sk->sk_error_report(sk);
}

static inline bool tls_bigint_increment(unsigned char *seq, int len)
{
        int i;

        for (i = len - 1; i >= 0; i--) {
                ++seq[i];
                if (seq[i] != 0)
                        break;
        }

        return (i == -1);
}

static inline struct tls_context *tls_get_ctx(const struct sock *sk)
{
        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 void tls_advance_record_sn(struct sock *sk,
                                         struct tls_prot_info *prot,
                                         struct cipher_context *ctx)
{
        if (tls_bigint_increment(ctx->rec_seq, prot->rec_seq_size))
                tls_err_abort(sk, EBADMSG);

        if (prot->version != TLS_1_3_VERSION)
                tls_bigint_increment(ctx->iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE,
                                     prot->iv_size);
}

static inline void tls_fill_prepend(struct tls_context *ctx,
                             char *buf,
                             size_t plaintext_len,
                             unsigned char record_type,
                             int version)
{
        struct tls_prot_info *prot = &ctx->prot_info;
        size_t pkt_len, iv_size = prot->iv_size;

        pkt_len = plaintext_len + prot->tag_size;
        if (version != TLS_1_3_VERSION) {
                pkt_len += iv_size;

                memcpy(buf + TLS_NONCE_OFFSET,
                       ctx->tx.iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE, iv_size);
        }

        /* we cover nonce explicit here as well, so buf should be of
         * size KTLS_DTLS_HEADER_SIZE + KTLS_DTLS_NONCE_EXPLICIT_SIZE
         */
        buf[0] = version == TLS_1_3_VERSION ?
                   TLS_RECORD_TYPE_DATA : record_type;
        /* Note that VERSION must be TLS_1_2 for both TLS1.2 and TLS1.3 */
        buf[1] = TLS_1_2_VERSION_MINOR;
        buf[2] = TLS_1_2_VERSION_MAJOR;
        /* we can use IV for nonce explicit according to spec */
        buf[3] = pkt_len >> 8;
        buf[4] = pkt_len & 0xFF;
}

static inline void tls_make_aad(char *buf,
                                size_t size,
                                char *record_sequence,
                                int record_sequence_size,
                                unsigned char record_type,
                                int version)
{
        if (version != TLS_1_3_VERSION) {
                memcpy(buf, record_sequence, record_sequence_size);
                buf += 8;
        } else {
                size += TLS_CIPHER_AES_GCM_128_TAG_SIZE;
        }

        buf[0] = version == TLS_1_3_VERSION ?
                  TLS_RECORD_TYPE_DATA : record_type;
        buf[1] = TLS_1_2_VERSION_MAJOR;
        buf[2] = TLS_1_2_VERSION_MINOR;
        buf[3] = size >> 8;
        buf[4] = size & 0xFF;
}

static inline void xor_iv_with_seq(int version, char *iv, char *seq)
{
        int i;

        if (version == TLS_1_3_VERSION) {
                for (i = 0; i < 8; i++)
                        iv[i + 4] ^= seq[i];
        }
}


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 = tls_get_ctx(sk);

        if (!ctx)
                return false;
        return !!tls_sw_ctx_tx(ctx);
}

void tls_sw_write_space(struct sock *sk, struct tls_context *ctx);
void tls_device_write_space(struct sock *sk, struct tls_context *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;
}

#if IS_ENABLED(CONFIG_TLS_DEVICE)
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);
}
#endif

/* 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) | 1);
}

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;
}

int __net_init tls_proc_init(struct net *net);
void __net_exit tls_proc_fini(struct net *net);

int tls_proccess_cmsg(struct sock *sk, struct msghdr *msg,
                      unsigned char *record_type);
int decrypt_skb(struct sock *sk, struct sk_buff *skb,
                struct scatterlist *sgout);
struct sk_buff *tls_encrypt_skb(struct sk_buff *skb);

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

int tls_sw_fallback_init(struct sock *sk,
                         struct tls_offload_context_tx *offload_ctx,
                         struct tls_crypto_info *crypto_info);

#ifdef CONFIG_TLS_DEVICE
void tls_device_init(void);
void tls_device_cleanup(void);
int tls_set_device_offload(struct sock *sk, struct tls_context *ctx);
void tls_device_free_resources_tx(struct sock *sk);
int tls_set_device_offload_rx(struct sock *sk, struct tls_context *ctx);
void tls_device_offload_cleanup_rx(struct sock *sk);
void tls_device_rx_resync_new_rec(struct sock *sk, u32 rcd_len, u32 seq);
void tls_offload_tx_resync_request(struct sock *sk, u32 got_seq, u32 exp_seq);
int tls_device_decrypted(struct sock *sk, struct tls_context *tls_ctx,
                         struct sk_buff *skb, struct strp_msg *rxm);
#else
static inline void tls_device_init(void) {}
static inline void tls_device_cleanup(void) {}

static inline int
tls_set_device_offload(struct sock *sk, struct tls_context *ctx)
{
        return -EOPNOTSUPP;
}

static inline void tls_device_free_resources_tx(struct sock *sk) {}

static inline int
tls_set_device_offload_rx(struct sock *sk, struct tls_context *ctx)
{
        return -EOPNOTSUPP;
}

static inline void tls_device_offload_cleanup_rx(struct sock *sk) {}
static inline void
tls_device_rx_resync_new_rec(struct sock *sk, u32 rcd_len, u32 seq) {}

static inline int
tls_device_decrypted(struct sock *sk, struct tls_context *tls_ctx,
                     struct sk_buff *skb, struct strp_msg *rxm)
{
        return 0;
}
#endif
#endif /* _TLS_OFFLOAD_H */