ktls: Close a race with setting so_error when dropping a connection.

[FreeBSD/FreeBSD.git] / sys / kern / uipc_ktls.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2014-2019 Netflix Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_inet.h"
#include "opt_inet6.h"
#include "opt_rss.h"

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/domainset.h>
#include <sys/ktls.h>
#include <sys/lock.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/rmlock.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/refcount.h>
#include <sys/smp.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/taskqueue.h>
#include <sys/kthread.h>
#include <sys/uio.h>
#include <sys/vmmeter.h>
#if defined(__aarch64__) || defined(__amd64__) || defined(__i386__)
#include <machine/pcb.h>
#endif
#include <machine/vmparam.h>
#include <net/if.h>
#include <net/if_var.h>
#ifdef RSS
#include <net/netisr.h>
#include <net/rss_config.h>
#endif
#include <net/route.h>
#include <net/route/nhop.h>
#if defined(INET) || defined(INET6)
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#endif
#include <netinet/tcp_var.h>
#ifdef TCP_OFFLOAD
#include <netinet/tcp_offload.h>
#endif
#include <opencrypto/xform.h>
#include <vm/uma_dbg.h>
#include <vm/vm.h>
#include <vm/vm_pageout.h>
#include <vm/vm_page.h>

struct ktls_wq {
        struct mtx      mtx;
        STAILQ_HEAD(, mbuf) m_head;
        STAILQ_HEAD(, socket) so_head;
        bool            running;
} __aligned(CACHE_LINE_SIZE);

struct ktls_domain_info {
        int count;
        int cpu[MAXCPU];
};

struct ktls_domain_info ktls_domains[MAXMEMDOM];
static struct ktls_wq *ktls_wq;
static struct proc *ktls_proc;
LIST_HEAD(, ktls_crypto_backend) ktls_backends;
static struct rmlock ktls_backends_lock;
static uma_zone_t ktls_session_zone;
static uint16_t ktls_cpuid_lookup[MAXCPU];

SYSCTL_NODE(_kern_ipc, OID_AUTO, tls, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "Kernel TLS offload");
SYSCTL_NODE(_kern_ipc_tls, OID_AUTO, stats, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "Kernel TLS offload stats");

static int ktls_allow_unload;
SYSCTL_INT(_kern_ipc_tls, OID_AUTO, allow_unload, CTLFLAG_RDTUN,
    &ktls_allow_unload, 0, "Allow software crypto modules to unload");

#ifdef RSS
static int ktls_bind_threads = 1;
#else
static int ktls_bind_threads;
#endif
SYSCTL_INT(_kern_ipc_tls, OID_AUTO, bind_threads, CTLFLAG_RDTUN,
    &ktls_bind_threads, 0,
    "Bind crypto threads to cores (1) or cores and domains (2) at boot");

static u_int ktls_maxlen = 16384;
SYSCTL_UINT(_kern_ipc_tls, OID_AUTO, maxlen, CTLFLAG_RWTUN,
    &ktls_maxlen, 0, "Maximum TLS record size");

static int ktls_number_threads;
SYSCTL_INT(_kern_ipc_tls_stats, OID_AUTO, threads, CTLFLAG_RD,
    &ktls_number_threads, 0,
    "Number of TLS threads in thread-pool");

static bool ktls_offload_enable;
SYSCTL_BOOL(_kern_ipc_tls, OID_AUTO, enable, CTLFLAG_RWTUN,
    &ktls_offload_enable, 0,
    "Enable support for kernel TLS offload");

static bool ktls_cbc_enable = true;
SYSCTL_BOOL(_kern_ipc_tls, OID_AUTO, cbc_enable, CTLFLAG_RWTUN,
    &ktls_cbc_enable, 1,
    "Enable Support of AES-CBC crypto for kernel TLS");

static COUNTER_U64_DEFINE_EARLY(ktls_tasks_active);
SYSCTL_COUNTER_U64(_kern_ipc_tls, OID_AUTO, tasks_active, CTLFLAG_RD,
    &ktls_tasks_active, "Number of active tasks");

static COUNTER_U64_DEFINE_EARLY(ktls_cnt_tx_pending);
SYSCTL_COUNTER_U64(_kern_ipc_tls_stats, OID_AUTO, sw_tx_pending, CTLFLAG_RD,
    &ktls_cnt_tx_pending,
    "Number of TLS 1.0 records waiting for earlier TLS records");

static COUNTER_U64_DEFINE_EARLY(ktls_cnt_tx_queued);
SYSCTL_COUNTER_U64(_kern_ipc_tls_stats, OID_AUTO, sw_tx_inqueue, CTLFLAG_RD,
    &ktls_cnt_tx_queued,
    "Number of TLS records in queue to tasks for SW encryption");

static COUNTER_U64_DEFINE_EARLY(ktls_cnt_rx_queued);
SYSCTL_COUNTER_U64(_kern_ipc_tls_stats, OID_AUTO, sw_rx_inqueue, CTLFLAG_RD,
    &ktls_cnt_rx_queued,
    "Number of TLS sockets in queue to tasks for SW decryption");

static COUNTER_U64_DEFINE_EARLY(ktls_offload_total);
SYSCTL_COUNTER_U64(_kern_ipc_tls_stats, OID_AUTO, offload_total,
    CTLFLAG_RD, &ktls_offload_total,
    "Total successful TLS setups (parameters set)");

static COUNTER_U64_DEFINE_EARLY(ktls_offload_enable_calls);
SYSCTL_COUNTER_U64(_kern_ipc_tls_stats, OID_AUTO, enable_calls,
    CTLFLAG_RD, &ktls_offload_enable_calls,
    "Total number of TLS enable calls made");

static COUNTER_U64_DEFINE_EARLY(ktls_offload_active);
SYSCTL_COUNTER_U64(_kern_ipc_tls_stats, OID_AUTO, active, CTLFLAG_RD,
    &ktls_offload_active, "Total Active TLS sessions");

static COUNTER_U64_DEFINE_EARLY(ktls_offload_corrupted_records);
SYSCTL_COUNTER_U64(_kern_ipc_tls_stats, OID_AUTO, corrupted_records, CTLFLAG_RD,
    &ktls_offload_corrupted_records, "Total corrupted TLS records received");

static COUNTER_U64_DEFINE_EARLY(ktls_offload_failed_crypto);
SYSCTL_COUNTER_U64(_kern_ipc_tls_stats, OID_AUTO, failed_crypto, CTLFLAG_RD,
    &ktls_offload_failed_crypto, "Total TLS crypto failures");

static COUNTER_U64_DEFINE_EARLY(ktls_switch_to_ifnet);
SYSCTL_COUNTER_U64(_kern_ipc_tls_stats, OID_AUTO, switch_to_ifnet, CTLFLAG_RD,
    &ktls_switch_to_ifnet, "TLS sessions switched from SW to ifnet");

static COUNTER_U64_DEFINE_EARLY(ktls_switch_to_sw);
SYSCTL_COUNTER_U64(_kern_ipc_tls_stats, OID_AUTO, switch_to_sw, CTLFLAG_RD,
    &ktls_switch_to_sw, "TLS sessions switched from ifnet to SW");

static COUNTER_U64_DEFINE_EARLY(ktls_switch_failed);
SYSCTL_COUNTER_U64(_kern_ipc_tls_stats, OID_AUTO, switch_failed, CTLFLAG_RD,
    &ktls_switch_failed, "TLS sessions unable to switch between SW and ifnet");

SYSCTL_NODE(_kern_ipc_tls, OID_AUTO, sw, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
    "Software TLS session stats");
SYSCTL_NODE(_kern_ipc_tls, OID_AUTO, ifnet, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
    "Hardware (ifnet) TLS session stats");
#ifdef TCP_OFFLOAD
SYSCTL_NODE(_kern_ipc_tls, OID_AUTO, toe, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
    "TOE TLS session stats");
#endif

static COUNTER_U64_DEFINE_EARLY(ktls_sw_cbc);
SYSCTL_COUNTER_U64(_kern_ipc_tls_sw, OID_AUTO, cbc, CTLFLAG_RD, &ktls_sw_cbc,
    "Active number of software TLS sessions using AES-CBC");

static COUNTER_U64_DEFINE_EARLY(ktls_sw_gcm);
SYSCTL_COUNTER_U64(_kern_ipc_tls_sw, OID_AUTO, gcm, CTLFLAG_RD, &ktls_sw_gcm,
    "Active number of software TLS sessions using AES-GCM");

static COUNTER_U64_DEFINE_EARLY(ktls_sw_chacha20);
SYSCTL_COUNTER_U64(_kern_ipc_tls_sw, OID_AUTO, chacha20, CTLFLAG_RD,
    &ktls_sw_chacha20,
    "Active number of software TLS sessions using Chacha20-Poly1305");

static COUNTER_U64_DEFINE_EARLY(ktls_ifnet_cbc);
SYSCTL_COUNTER_U64(_kern_ipc_tls_ifnet, OID_AUTO, cbc, CTLFLAG_RD,
    &ktls_ifnet_cbc,
    "Active number of ifnet TLS sessions using AES-CBC");

static COUNTER_U64_DEFINE_EARLY(ktls_ifnet_gcm);
SYSCTL_COUNTER_U64(_kern_ipc_tls_ifnet, OID_AUTO, gcm, CTLFLAG_RD,
    &ktls_ifnet_gcm,
    "Active number of ifnet TLS sessions using AES-GCM");

static COUNTER_U64_DEFINE_EARLY(ktls_ifnet_chacha20);
SYSCTL_COUNTER_U64(_kern_ipc_tls_ifnet, OID_AUTO, chacha20, CTLFLAG_RD,
    &ktls_ifnet_chacha20,
    "Active number of ifnet TLS sessions using Chacha20-Poly1305");

static COUNTER_U64_DEFINE_EARLY(ktls_ifnet_reset);
SYSCTL_COUNTER_U64(_kern_ipc_tls_ifnet, OID_AUTO, reset, CTLFLAG_RD,
    &ktls_ifnet_reset, "TLS sessions updated to a new ifnet send tag");

static COUNTER_U64_DEFINE_EARLY(ktls_ifnet_reset_dropped);
SYSCTL_COUNTER_U64(_kern_ipc_tls_ifnet, OID_AUTO, reset_dropped, CTLFLAG_RD,
    &ktls_ifnet_reset_dropped,
    "TLS sessions dropped after failing to update ifnet send tag");

static COUNTER_U64_DEFINE_EARLY(ktls_ifnet_reset_failed);
SYSCTL_COUNTER_U64(_kern_ipc_tls_ifnet, OID_AUTO, reset_failed, CTLFLAG_RD,
    &ktls_ifnet_reset_failed,
    "TLS sessions that failed to allocate a new ifnet send tag");

static int ktls_ifnet_permitted;
SYSCTL_UINT(_kern_ipc_tls_ifnet, OID_AUTO, permitted, CTLFLAG_RWTUN,
    &ktls_ifnet_permitted, 1,
    "Whether to permit hardware (ifnet) TLS sessions");

#ifdef TCP_OFFLOAD
static COUNTER_U64_DEFINE_EARLY(ktls_toe_cbc);
SYSCTL_COUNTER_U64(_kern_ipc_tls_toe, OID_AUTO, cbc, CTLFLAG_RD,
    &ktls_toe_cbc,
    "Active number of TOE TLS sessions using AES-CBC");

static COUNTER_U64_DEFINE_EARLY(ktls_toe_gcm);
SYSCTL_COUNTER_U64(_kern_ipc_tls_toe, OID_AUTO, gcm, CTLFLAG_RD,
    &ktls_toe_gcm,
    "Active number of TOE TLS sessions using AES-GCM");

static COUNTER_U64_DEFINE_EARLY(ktls_toe_chacha20);
SYSCTL_COUNTER_U64(_kern_ipc_tls_toe, OID_AUTO, chacha20, CTLFLAG_RD,
    &ktls_toe_chacha20,
    "Active number of TOE TLS sessions using Chacha20-Poly1305");
#endif

static MALLOC_DEFINE(M_KTLS, "ktls", "Kernel TLS");

static void ktls_cleanup(struct ktls_session *tls);
#if defined(INET) || defined(INET6)
static void ktls_reset_send_tag(void *context, int pending);
#endif
static void ktls_work_thread(void *ctx);

int
ktls_crypto_backend_register(struct ktls_crypto_backend *be)
{
        struct ktls_crypto_backend *curr_be, *tmp;

        if (be->api_version != KTLS_API_VERSION) {
                printf("KTLS: API version mismatch (%d vs %d) for %s\n",
                    be->api_version, KTLS_API_VERSION,
                    be->name);
                return (EINVAL);
        }

        rm_wlock(&ktls_backends_lock);
        printf("KTLS: Registering crypto method %s with prio %d\n",
               be->name, be->prio);
        if (LIST_EMPTY(&ktls_backends)) {
                LIST_INSERT_HEAD(&ktls_backends, be, next);
        } else {
                LIST_FOREACH_SAFE(curr_be, &ktls_backends, next, tmp) {
                        if (curr_be->prio < be->prio) {
                                LIST_INSERT_BEFORE(curr_be, be, next);
                                break;
                        }
                        if (LIST_NEXT(curr_be, next) == NULL) {
                                LIST_INSERT_AFTER(curr_be, be, next);
                                break;
                        }
                }
        }
        rm_wunlock(&ktls_backends_lock);
        return (0);
}

int
ktls_crypto_backend_deregister(struct ktls_crypto_backend *be)
{
        struct ktls_crypto_backend *tmp;

        /*
         * Don't error if the backend isn't registered.  This permits
         * MOD_UNLOAD handlers to use this function unconditionally.
         */
        rm_wlock(&ktls_backends_lock);
        LIST_FOREACH(tmp, &ktls_backends, next) {
                if (tmp == be)
                        break;
        }
        if (tmp == NULL) {
                rm_wunlock(&ktls_backends_lock);
                return (0);
        }

        if (!ktls_allow_unload) {
                rm_wunlock(&ktls_backends_lock);
                printf(
                    "KTLS: Deregistering crypto method %s is not supported\n",
                    be->name);
                return (EBUSY);
        }

        if (be->use_count) {
                rm_wunlock(&ktls_backends_lock);
                return (EBUSY);
        }

        LIST_REMOVE(be, next);
        rm_wunlock(&ktls_backends_lock);
        return (0);
}

#if defined(INET) || defined(INET6)
static u_int
ktls_get_cpu(struct socket *so)
{
        struct inpcb *inp;
#ifdef NUMA
        struct ktls_domain_info *di;
#endif
        u_int cpuid;

        inp = sotoinpcb(so);
#ifdef RSS
        cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
        if (cpuid != NETISR_CPUID_NONE)
                return (cpuid);
#endif
        /*
         * Just use the flowid to shard connections in a repeatable
         * fashion.  Note that some crypto backends rely on the
         * serialization provided by having the same connection use
         * the same queue.
         */
#ifdef NUMA
        if (ktls_bind_threads > 1 && inp->inp_numa_domain != M_NODOM) {
                di = &ktls_domains[inp->inp_numa_domain];
                cpuid = di->cpu[inp->inp_flowid % di->count];
        } else
#endif
                cpuid = ktls_cpuid_lookup[inp->inp_flowid % ktls_number_threads];
        return (cpuid);
}
#endif

static void
ktls_init(void *dummy __unused)
{
        struct thread *td;
        struct pcpu *pc;
        cpuset_t mask;
        int count, domain, error, i;

        rm_init(&ktls_backends_lock, "ktls backends");
        LIST_INIT(&ktls_backends);

        ktls_wq = malloc(sizeof(*ktls_wq) * (mp_maxid + 1), M_KTLS,
            M_WAITOK | M_ZERO);

        ktls_session_zone = uma_zcreate("ktls_session",
            sizeof(struct ktls_session),
            NULL, NULL, NULL, NULL,
            UMA_ALIGN_CACHE, 0);

        /*
         * Initialize the workqueues to run the TLS work.  We create a
         * work queue for each CPU.
         */
        CPU_FOREACH(i) {
                STAILQ_INIT(&ktls_wq[i].m_head);
                STAILQ_INIT(&ktls_wq[i].so_head);
                mtx_init(&ktls_wq[i].mtx, "ktls work queue", NULL, MTX_DEF);
                error = kproc_kthread_add(ktls_work_thread, &ktls_wq[i],
                    &ktls_proc, &td, 0, 0, "KTLS", "thr_%d", i);
                if (error)
                        panic("Can't add KTLS thread %d error %d", i, error);

                /*
                 * Bind threads to cores.  If ktls_bind_threads is >
                 * 1, then we bind to the NUMA domain.
                 */
                if (ktls_bind_threads) {
                        if (ktls_bind_threads > 1) {
                                pc = pcpu_find(i);
                                domain = pc->pc_domain;
                                CPU_COPY(&cpuset_domain[domain], &mask);
                                count = ktls_domains[domain].count;
                                ktls_domains[domain].cpu[count] = i;
                                ktls_domains[domain].count++;
                        } else {
                                CPU_SETOF(i, &mask);
                        }
                        error = cpuset_setthread(td->td_tid, &mask);
                        if (error)
                                panic(
                            "Unable to bind KTLS thread for CPU %d error %d",
                                     i, error);
                }
                ktls_cpuid_lookup[ktls_number_threads] = i;
                ktls_number_threads++;
        }

        /*
         * If we somehow have an empty domain, fall back to choosing
         * among all KTLS threads.
         */
        if (ktls_bind_threads > 1) {
                for (i = 0; i < vm_ndomains; i++) {
                        if (ktls_domains[i].count == 0) {
                                ktls_bind_threads = 1;
                                break;
                        }
                }
        }

        if (bootverbose)
                printf("KTLS: Initialized %d threads\n", ktls_number_threads);
}
SYSINIT(ktls, SI_SUB_SMP + 1, SI_ORDER_ANY, ktls_init, NULL);

#if defined(INET) || defined(INET6)
static int
ktls_create_session(struct socket *so, struct tls_enable *en,
    struct ktls_session **tlsp)
{
        struct ktls_session *tls;
        int error;

        /* Only TLS 1.0 - 1.3 are supported. */
        if (en->tls_vmajor != TLS_MAJOR_VER_ONE)
                return (EINVAL);
        if (en->tls_vminor < TLS_MINOR_VER_ZERO ||
            en->tls_vminor > TLS_MINOR_VER_THREE)
                return (EINVAL);

        if (en->auth_key_len < 0 || en->auth_key_len > TLS_MAX_PARAM_SIZE)
                return (EINVAL);
        if (en->cipher_key_len < 0 || en->cipher_key_len > TLS_MAX_PARAM_SIZE)
                return (EINVAL);
        if (en->iv_len < 0 || en->iv_len > sizeof(tls->params.iv))
                return (EINVAL);

        /* All supported algorithms require a cipher key. */
        if (en->cipher_key_len == 0)
                return (EINVAL);

        /* No flags are currently supported. */
        if (en->flags != 0)
                return (EINVAL);

        /* Common checks for supported algorithms. */
        switch (en->cipher_algorithm) {
        case CRYPTO_AES_NIST_GCM_16:
                /*
                 * auth_algorithm isn't used, but permit GMAC values
                 * for compatibility.
                 */
                switch (en->auth_algorithm) {
                case 0:
#ifdef COMPAT_FREEBSD12
                /* XXX: Really 13.0-current COMPAT. */
                case CRYPTO_AES_128_NIST_GMAC:
                case CRYPTO_AES_192_NIST_GMAC:
                case CRYPTO_AES_256_NIST_GMAC:
#endif
                        break;
                default:
                        return (EINVAL);
                }
                if (en->auth_key_len != 0)
                        return (EINVAL);
                switch (en->tls_vminor) {
                case TLS_MINOR_VER_TWO:
                        if (en->iv_len != TLS_AEAD_GCM_LEN)
                                return (EINVAL);
                        break;
                case TLS_MINOR_VER_THREE:
                        if (en->iv_len != TLS_1_3_GCM_IV_LEN)
                                return (EINVAL);
                        break;
                default:
                        return (EINVAL);
                }
                break;
        case CRYPTO_AES_CBC:
                switch (en->auth_algorithm) {
                case CRYPTO_SHA1_HMAC:
                        break;
                case CRYPTO_SHA2_256_HMAC:
                case CRYPTO_SHA2_384_HMAC:
                        if (en->tls_vminor != TLS_MINOR_VER_TWO)
                                return (EINVAL);
                        break;
                default:
                        return (EINVAL);
                }
                if (en->auth_key_len == 0)
                        return (EINVAL);

                /*
                 * TLS 1.0 requires an implicit IV.  TLS 1.1 and 1.2
                 * use explicit IVs.
                 */
                switch (en->tls_vminor) {
                case TLS_MINOR_VER_ZERO:
                        if (en->iv_len != TLS_CBC_IMPLICIT_IV_LEN)
                                return (EINVAL);
                        break;
                case TLS_MINOR_VER_ONE:
                case TLS_MINOR_VER_TWO:
                        /* Ignore any supplied IV. */
                        en->iv_len = 0;
                        break;
                default:
                        return (EINVAL);
                }
                break;
        case CRYPTO_CHACHA20_POLY1305:
                if (en->auth_algorithm != 0 || en->auth_key_len != 0)
                        return (EINVAL);
                if (en->tls_vminor != TLS_MINOR_VER_TWO &&
                    en->tls_vminor != TLS_MINOR_VER_THREE)
                        return (EINVAL);
                if (en->iv_len != TLS_CHACHA20_IV_LEN)
                        return (EINVAL);
                break;
        default:
                return (EINVAL);
        }

        tls = uma_zalloc(ktls_session_zone, M_WAITOK | M_ZERO);

        counter_u64_add(ktls_offload_active, 1);

        refcount_init(&tls->refcount, 1);
        TASK_INIT(&tls->reset_tag_task, 0, ktls_reset_send_tag, tls);

        tls->wq_index = ktls_get_cpu(so);

        tls->params.cipher_algorithm = en->cipher_algorithm;
        tls->params.auth_algorithm = en->auth_algorithm;
        tls->params.tls_vmajor = en->tls_vmajor;
        tls->params.tls_vminor = en->tls_vminor;
        tls->params.flags = en->flags;
        tls->params.max_frame_len = min(TLS_MAX_MSG_SIZE_V10_2, ktls_maxlen);

        /* Set the header and trailer lengths. */
        tls->params.tls_hlen = sizeof(struct tls_record_layer);
        switch (en->cipher_algorithm) {
        case CRYPTO_AES_NIST_GCM_16:
                /*
                 * TLS 1.2 uses a 4 byte implicit IV with an explicit 8 byte
                 * nonce.  TLS 1.3 uses a 12 byte implicit IV.
                 */
                if (en->tls_vminor < TLS_MINOR_VER_THREE)
                        tls->params.tls_hlen += sizeof(uint64_t);
                tls->params.tls_tlen = AES_GMAC_HASH_LEN;
                tls->params.tls_bs = 1;
                break;
        case CRYPTO_AES_CBC:
                switch (en->auth_algorithm) {
                case CRYPTO_SHA1_HMAC:
                        if (en->tls_vminor == TLS_MINOR_VER_ZERO) {
                                /* Implicit IV, no nonce. */
                                tls->sequential_records = true;
                                tls->next_seqno = be64dec(en->rec_seq);
                                STAILQ_INIT(&tls->pending_records);
                        } else {
                                tls->params.tls_hlen += AES_BLOCK_LEN;
                        }
                        tls->params.tls_tlen = AES_BLOCK_LEN +
                            SHA1_HASH_LEN;
                        break;
                case CRYPTO_SHA2_256_HMAC:
                        tls->params.tls_hlen += AES_BLOCK_LEN;
                        tls->params.tls_tlen = AES_BLOCK_LEN +
                            SHA2_256_HASH_LEN;
                        break;
                case CRYPTO_SHA2_384_HMAC:
                        tls->params.tls_hlen += AES_BLOCK_LEN;
                        tls->params.tls_tlen = AES_BLOCK_LEN +
                            SHA2_384_HASH_LEN;
                        break;
                default:
                        panic("invalid hmac");
                }
                tls->params.tls_bs = AES_BLOCK_LEN;
                break;
        case CRYPTO_CHACHA20_POLY1305:
                /*
                 * Chacha20 uses a 12 byte implicit IV.
                 */
                tls->params.tls_tlen = POLY1305_HASH_LEN;
                tls->params.tls_bs = 1;
                break;
        default:
                panic("invalid cipher");
        }

        /*
         * TLS 1.3 includes optional padding which we do not support,
         * and also puts the "real" record type at the end of the
         * encrypted data.
         */
        if (en->tls_vminor == TLS_MINOR_VER_THREE)
                tls->params.tls_tlen += sizeof(uint8_t);

        KASSERT(tls->params.tls_hlen <= MBUF_PEXT_HDR_LEN,
            ("TLS header length too long: %d", tls->params.tls_hlen));
        KASSERT(tls->params.tls_tlen <= MBUF_PEXT_TRAIL_LEN,
            ("TLS trailer length too long: %d", tls->params.tls_tlen));

        if (en->auth_key_len != 0) {
                tls->params.auth_key_len = en->auth_key_len;
                tls->params.auth_key = malloc(en->auth_key_len, M_KTLS,
                    M_WAITOK);
                error = copyin(en->auth_key, tls->params.auth_key,
                    en->auth_key_len);
                if (error)
                        goto out;
        }

        tls->params.cipher_key_len = en->cipher_key_len;
        tls->params.cipher_key = malloc(en->cipher_key_len, M_KTLS, M_WAITOK);
        error = copyin(en->cipher_key, tls->params.cipher_key,
            en->cipher_key_len);
        if (error)
                goto out;

        /*
         * This holds the implicit portion of the nonce for AEAD
         * ciphers and the initial implicit IV for TLS 1.0.  The
         * explicit portions of the IV are generated in ktls_frame().
         */
        if (en->iv_len != 0) {
                tls->params.iv_len = en->iv_len;
                error = copyin(en->iv, tls->params.iv, en->iv_len);
                if (error)
                        goto out;

                /*
                 * For TLS 1.2 with GCM, generate an 8-byte nonce as a
                 * counter to generate unique explicit IVs.
                 *
                 * Store this counter in the last 8 bytes of the IV
                 * array so that it is 8-byte aligned.
                 */
                if (en->cipher_algorithm == CRYPTO_AES_NIST_GCM_16 &&
                    en->tls_vminor == TLS_MINOR_VER_TWO)
                        arc4rand(tls->params.iv + 8, sizeof(uint64_t), 0);
        }

        *tlsp = tls;
        return (0);

out:
        ktls_free(tls);
        return (error);
}

static struct ktls_session *
ktls_clone_session(struct ktls_session *tls)
{
        struct ktls_session *tls_new;

        tls_new = uma_zalloc(ktls_session_zone, M_WAITOK | M_ZERO);

        counter_u64_add(ktls_offload_active, 1);

        refcount_init(&tls_new->refcount, 1);
        TASK_INIT(&tls_new->reset_tag_task, 0, ktls_reset_send_tag, tls_new);

        /* Copy fields from existing session. */
        tls_new->params = tls->params;
        tls_new->wq_index = tls->wq_index;

        /* Deep copy keys. */
        if (tls_new->params.auth_key != NULL) {
                tls_new->params.auth_key = malloc(tls->params.auth_key_len,
                    M_KTLS, M_WAITOK);
                memcpy(tls_new->params.auth_key, tls->params.auth_key,
                    tls->params.auth_key_len);
        }

        tls_new->params.cipher_key = malloc(tls->params.cipher_key_len, M_KTLS,
            M_WAITOK);
        memcpy(tls_new->params.cipher_key, tls->params.cipher_key,
            tls->params.cipher_key_len);

        return (tls_new);
}
#endif

static void
ktls_cleanup(struct ktls_session *tls)
{

        counter_u64_add(ktls_offload_active, -1);
        switch (tls->mode) {
        case TCP_TLS_MODE_SW:
                MPASS(tls->be != NULL);
                switch (tls->params.cipher_algorithm) {
                case CRYPTO_AES_CBC:
                        counter_u64_add(ktls_sw_cbc, -1);
                        break;
                case CRYPTO_AES_NIST_GCM_16:
                        counter_u64_add(ktls_sw_gcm, -1);
                        break;
                case CRYPTO_CHACHA20_POLY1305:
                        counter_u64_add(ktls_sw_chacha20, -1);
                        break;
                }
                tls->free(tls);
                break;
        case TCP_TLS_MODE_IFNET:
                switch (tls->params.cipher_algorithm) {
                case CRYPTO_AES_CBC:
                        counter_u64_add(ktls_ifnet_cbc, -1);
                        break;
                case CRYPTO_AES_NIST_GCM_16:
                        counter_u64_add(ktls_ifnet_gcm, -1);
                        break;
                case CRYPTO_CHACHA20_POLY1305:
                        counter_u64_add(ktls_ifnet_chacha20, -1);
                        break;
                }
                if (tls->snd_tag != NULL)
                        m_snd_tag_rele(tls->snd_tag);
                break;
#ifdef TCP_OFFLOAD
        case TCP_TLS_MODE_TOE:
                switch (tls->params.cipher_algorithm) {
                case CRYPTO_AES_CBC:
                        counter_u64_add(ktls_toe_cbc, -1);
                        break;
                case CRYPTO_AES_NIST_GCM_16:
                        counter_u64_add(ktls_toe_gcm, -1);
                        break;
                case CRYPTO_CHACHA20_POLY1305:
                        counter_u64_add(ktls_toe_chacha20, -1);
                        break;
                }
                break;
#endif
        }
        if (tls->params.auth_key != NULL) {
                zfree(tls->params.auth_key, M_KTLS);
                tls->params.auth_key = NULL;
                tls->params.auth_key_len = 0;
        }
        if (tls->params.cipher_key != NULL) {
                zfree(tls->params.cipher_key, M_KTLS);
                tls->params.cipher_key = NULL;
                tls->params.cipher_key_len = 0;
        }
        explicit_bzero(tls->params.iv, sizeof(tls->params.iv));
}

#if defined(INET) || defined(INET6)

#ifdef TCP_OFFLOAD
static int
ktls_try_toe(struct socket *so, struct ktls_session *tls, int direction)
{
        struct inpcb *inp;
        struct tcpcb *tp;
        int error;

        inp = so->so_pcb;
        INP_WLOCK(inp);
        if (inp->inp_flags2 & INP_FREED) {
                INP_WUNLOCK(inp);
                return (ECONNRESET);
        }
        if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
                INP_WUNLOCK(inp);
                return (ECONNRESET);
        }
        if (inp->inp_socket == NULL) {
                INP_WUNLOCK(inp);
                return (ECONNRESET);
        }
        tp = intotcpcb(inp);
        if (!(tp->t_flags & TF_TOE)) {
                INP_WUNLOCK(inp);
                return (EOPNOTSUPP);
        }

        error = tcp_offload_alloc_tls_session(tp, tls, direction);
        INP_WUNLOCK(inp);
        if (error == 0) {
                tls->mode = TCP_TLS_MODE_TOE;
                switch (tls->params.cipher_algorithm) {
                case CRYPTO_AES_CBC:
                        counter_u64_add(ktls_toe_cbc, 1);
                        break;
                case CRYPTO_AES_NIST_GCM_16:
                        counter_u64_add(ktls_toe_gcm, 1);
                        break;
                case CRYPTO_CHACHA20_POLY1305:
                        counter_u64_add(ktls_toe_chacha20, 1);
                        break;
                }
        }
        return (error);
}
#endif

/*
 * Common code used when first enabling ifnet TLS on a connection or
 * when allocating a new ifnet TLS session due to a routing change.
 * This function allocates a new TLS send tag on whatever interface
 * the connection is currently routed over.
 */
static int
ktls_alloc_snd_tag(struct inpcb *inp, struct ktls_session *tls, bool force,
    struct m_snd_tag **mstp)
{
        union if_snd_tag_alloc_params params;
        struct ifnet *ifp;
        struct nhop_object *nh;
        struct tcpcb *tp;
        int error;

        INP_RLOCK(inp);
        if (inp->inp_flags2 & INP_FREED) {
                INP_RUNLOCK(inp);
                return (ECONNRESET);
        }
        if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
                INP_RUNLOCK(inp);
                return (ECONNRESET);
        }
        if (inp->inp_socket == NULL) {
                INP_RUNLOCK(inp);
                return (ECONNRESET);
        }
        tp = intotcpcb(inp);

        /*
         * Check administrative controls on ifnet TLS to determine if
         * ifnet TLS should be denied.
         *
         * - Always permit 'force' requests.
         * - ktls_ifnet_permitted == 0: always deny.
         */
        if (!force && ktls_ifnet_permitted == 0) {
                INP_RUNLOCK(inp);
                return (ENXIO);
        }

        /*
         * XXX: Use the cached route in the inpcb to find the
         * interface.  This should perhaps instead use
         * rtalloc1_fib(dst, 0, 0, fibnum).  Since KTLS is only
         * enabled after a connection has completed key negotiation in
         * userland, the cached route will be present in practice.
         */
        nh = inp->inp_route.ro_nh;
        if (nh == NULL) {
                INP_RUNLOCK(inp);
                return (ENXIO);
        }
        ifp = nh->nh_ifp;
        if_ref(ifp);

        /*
         * Allocate a TLS + ratelimit tag if the connection has an
         * existing pacing rate.
         */
        if (tp->t_pacing_rate != -1 &&
            (ifp->if_capenable & IFCAP_TXTLS_RTLMT) != 0) {
                params.hdr.type = IF_SND_TAG_TYPE_TLS_RATE_LIMIT;
                params.tls_rate_limit.inp = inp;
                params.tls_rate_limit.tls = tls;
                params.tls_rate_limit.max_rate = tp->t_pacing_rate;
        } else {
                params.hdr.type = IF_SND_TAG_TYPE_TLS;
                params.tls.inp = inp;
                params.tls.tls = tls;
        }
        params.hdr.flowid = inp->inp_flowid;
        params.hdr.flowtype = inp->inp_flowtype;
        params.hdr.numa_domain = inp->inp_numa_domain;
        INP_RUNLOCK(inp);

        if ((ifp->if_capenable & IFCAP_MEXTPG) == 0) {
                error = EOPNOTSUPP;
                goto out;
        }
        if (inp->inp_vflag & INP_IPV6) {
                if ((ifp->if_capenable & IFCAP_TXTLS6) == 0) {
                        error = EOPNOTSUPP;
                        goto out;
                }
        } else {
                if ((ifp->if_capenable & IFCAP_TXTLS4) == 0) {
                        error = EOPNOTSUPP;
                        goto out;
                }
        }
        error = m_snd_tag_alloc(ifp, &params, mstp);
out:
        if_rele(ifp);
        return (error);
}

static int
ktls_try_ifnet(struct socket *so, struct ktls_session *tls, bool force)
{
        struct m_snd_tag *mst;
        int error;

        error = ktls_alloc_snd_tag(so->so_pcb, tls, force, &mst);
        if (error == 0) {
                tls->mode = TCP_TLS_MODE_IFNET;
                tls->snd_tag = mst;
                switch (tls->params.cipher_algorithm) {
                case CRYPTO_AES_CBC:
                        counter_u64_add(ktls_ifnet_cbc, 1);
                        break;
                case CRYPTO_AES_NIST_GCM_16:
                        counter_u64_add(ktls_ifnet_gcm, 1);
                        break;
                case CRYPTO_CHACHA20_POLY1305:
                        counter_u64_add(ktls_ifnet_chacha20, 1);
                        break;
                }
        }
        return (error);
}

static int
ktls_try_sw(struct socket *so, struct ktls_session *tls, int direction)
{
        struct rm_priotracker prio;
        struct ktls_crypto_backend *be;

        /*
         * Choose the best software crypto backend.  Backends are
         * stored in sorted priority order (larget value == most
         * important at the head of the list), so this just stops on
         * the first backend that claims the session by returning
         * success.
         */
        if (ktls_allow_unload)
                rm_rlock(&ktls_backends_lock, &prio);
        LIST_FOREACH(be, &ktls_backends, next) {
                if (be->try(so, tls, direction) == 0)
                        break;
                KASSERT(tls->cipher == NULL,
                    ("ktls backend leaked a cipher pointer"));
        }
        if (be != NULL) {
                if (ktls_allow_unload)
                        be->use_count++;
                tls->be = be;
        }
        if (ktls_allow_unload)
                rm_runlock(&ktls_backends_lock, &prio);
        if (be == NULL)
                return (EOPNOTSUPP);
        tls->mode = TCP_TLS_MODE_SW;
        switch (tls->params.cipher_algorithm) {
        case CRYPTO_AES_CBC:
                counter_u64_add(ktls_sw_cbc, 1);
                break;
        case CRYPTO_AES_NIST_GCM_16:
                counter_u64_add(ktls_sw_gcm, 1);
                break;
        case CRYPTO_CHACHA20_POLY1305:
                counter_u64_add(ktls_sw_chacha20, 1);
                break;
        }
        return (0);
}

/*
 * KTLS RX stores data in the socket buffer as a list of TLS records,
 * where each record is stored as a control message containg the TLS
 * header followed by data mbufs containing the decrypted data.  This
 * is different from KTLS TX which always uses an mb_ext_pgs mbuf for
 * both encrypted and decrypted data.  TLS records decrypted by a NIC
 * should be queued to the socket buffer as records, but encrypted
 * data which needs to be decrypted by software arrives as a stream of
 * regular mbufs which need to be converted.  In addition, there may
 * already be pending encrypted data in the socket buffer when KTLS RX
 * is enabled.
 *
 * To manage not-yet-decrypted data for KTLS RX, the following scheme
 * is used:
 *
 * - A single chain of NOTREADY mbufs is hung off of sb_mtls.
 *
 * - ktls_check_rx checks this chain of mbufs reading the TLS header
 *   from the first mbuf.  Once all of the data for that TLS record is
 *   queued, the socket is queued to a worker thread.
 *
 * - The worker thread calls ktls_decrypt to decrypt TLS records in
 *   the TLS chain.  Each TLS record is detached from the TLS chain,
 *   decrypted, and inserted into the regular socket buffer chain as
 *   record starting with a control message holding the TLS header and
 *   a chain of mbufs holding the encrypted data.
 */

static void
sb_mark_notready(struct sockbuf *sb)
{
        struct mbuf *m;

        m = sb->sb_mb;
        sb->sb_mtls = m;
        sb->sb_mb = NULL;
        sb->sb_mbtail = NULL;
        sb->sb_lastrecord = NULL;
        for (; m != NULL; m = m->m_next) {
                KASSERT(m->m_nextpkt == NULL, ("%s: m_nextpkt != NULL",
                    __func__));
                KASSERT((m->m_flags & M_NOTAVAIL) == 0, ("%s: mbuf not avail",
                    __func__));
                KASSERT(sb->sb_acc >= m->m_len, ("%s: sb_acc < m->m_len",
                    __func__));
                m->m_flags |= M_NOTREADY;
                sb->sb_acc -= m->m_len;
                sb->sb_tlscc += m->m_len;
                sb->sb_mtlstail = m;
        }
        KASSERT(sb->sb_acc == 0 && sb->sb_tlscc == sb->sb_ccc,
            ("%s: acc %u tlscc %u ccc %u", __func__, sb->sb_acc, sb->sb_tlscc,
            sb->sb_ccc));
}

int
ktls_enable_rx(struct socket *so, struct tls_enable *en)
{
        struct ktls_session *tls;
        int error;

        if (!ktls_offload_enable)
                return (ENOTSUP);
        if (SOLISTENING(so))
                return (EINVAL);

        counter_u64_add(ktls_offload_enable_calls, 1);

        /*
         * This should always be true since only the TCP socket option
         * invokes this function.
         */
        if (so->so_proto->pr_protocol != IPPROTO_TCP)
                return (EINVAL);

        /*
         * XXX: Don't overwrite existing sessions.  We should permit
         * this to support rekeying in the future.
         */
        if (so->so_rcv.sb_tls_info != NULL)
                return (EALREADY);

        if (en->cipher_algorithm == CRYPTO_AES_CBC && !ktls_cbc_enable)
                return (ENOTSUP);

        error = ktls_create_session(so, en, &tls);
        if (error)
                return (error);

#ifdef TCP_OFFLOAD
        error = ktls_try_toe(so, tls, KTLS_RX);
        if (error)
#endif
                error = ktls_try_sw(so, tls, KTLS_RX);

        if (error) {
                ktls_free(tls);
                return (error);
        }

        /* Mark the socket as using TLS offload. */
        SOCKBUF_LOCK(&so->so_rcv);
        so->so_rcv.sb_tls_seqno = be64dec(en->rec_seq);
        so->so_rcv.sb_tls_info = tls;
        so->so_rcv.sb_flags |= SB_TLS_RX;

        /* Mark existing data as not ready until it can be decrypted. */
        if (tls->mode != TCP_TLS_MODE_TOE) {
                sb_mark_notready(&so->so_rcv);
                ktls_check_rx(&so->so_rcv);
        }
        SOCKBUF_UNLOCK(&so->so_rcv);

        counter_u64_add(ktls_offload_total, 1);

        return (0);
}

int
ktls_enable_tx(struct socket *so, struct tls_enable *en)
{
        struct ktls_session *tls;
        struct inpcb *inp;
        int error;

        if (!ktls_offload_enable)
                return (ENOTSUP);
        if (SOLISTENING(so))
                return (EINVAL);

        counter_u64_add(ktls_offload_enable_calls, 1);

        /*
         * This should always be true since only the TCP socket option
         * invokes this function.
         */
        if (so->so_proto->pr_protocol != IPPROTO_TCP)
                return (EINVAL);

        /*
         * XXX: Don't overwrite existing sessions.  We should permit
         * this to support rekeying in the future.
         */
        if (so->so_snd.sb_tls_info != NULL)
                return (EALREADY);

        if (en->cipher_algorithm == CRYPTO_AES_CBC && !ktls_cbc_enable)
                return (ENOTSUP);

        /* TLS requires ext pgs */
        if (mb_use_ext_pgs == 0)
                return (ENXIO);

        error = ktls_create_session(so, en, &tls);
        if (error)
                return (error);

        /* Prefer TOE -> ifnet TLS -> software TLS. */
#ifdef TCP_OFFLOAD
        error = ktls_try_toe(so, tls, KTLS_TX);
        if (error)
#endif
                error = ktls_try_ifnet(so, tls, false);
        if (error)
                error = ktls_try_sw(so, tls, KTLS_TX);

        if (error) {
                ktls_free(tls);
                return (error);
        }

        error = SOCK_IO_SEND_LOCK(so, SBL_WAIT);
        if (error) {
                ktls_free(tls);
                return (error);
        }

        /*
         * Write lock the INP when setting sb_tls_info so that
         * routines in tcp_ratelimit.c can read sb_tls_info while
         * holding the INP lock.
         */
        inp = so->so_pcb;
        INP_WLOCK(inp);
        SOCKBUF_LOCK(&so->so_snd);
        so->so_snd.sb_tls_seqno = be64dec(en->rec_seq);
        so->so_snd.sb_tls_info = tls;
        if (tls->mode != TCP_TLS_MODE_SW)
                so->so_snd.sb_flags |= SB_TLS_IFNET;
        SOCKBUF_UNLOCK(&so->so_snd);
        INP_WUNLOCK(inp);
        SOCK_IO_SEND_UNLOCK(so);

        counter_u64_add(ktls_offload_total, 1);

        return (0);
}

int
ktls_get_rx_mode(struct socket *so)
{
        struct ktls_session *tls;
        struct inpcb *inp;
        int mode;

        if (SOLISTENING(so))
                return (EINVAL);
        inp = so->so_pcb;
        INP_WLOCK_ASSERT(inp);
        SOCKBUF_LOCK(&so->so_rcv);
        tls = so->so_rcv.sb_tls_info;
        if (tls == NULL)
                mode = TCP_TLS_MODE_NONE;
        else
                mode = tls->mode;
        SOCKBUF_UNLOCK(&so->so_rcv);
        return (mode);
}

int
ktls_get_tx_mode(struct socket *so)
{
        struct ktls_session *tls;
        struct inpcb *inp;
        int mode;

        if (SOLISTENING(so))
                return (EINVAL);
        inp = so->so_pcb;
        INP_WLOCK_ASSERT(inp);
        SOCKBUF_LOCK(&so->so_snd);
        tls = so->so_snd.sb_tls_info;
        if (tls == NULL)
                mode = TCP_TLS_MODE_NONE;
        else
                mode = tls->mode;
        SOCKBUF_UNLOCK(&so->so_snd);
        return (mode);
}

/*
 * Switch between SW and ifnet TLS sessions as requested.
 */
int
ktls_set_tx_mode(struct socket *so, int mode)
{
        struct ktls_session *tls, *tls_new;
        struct inpcb *inp;
        int error;

        if (SOLISTENING(so))
                return (EINVAL);
        switch (mode) {
        case TCP_TLS_MODE_SW:
        case TCP_TLS_MODE_IFNET:
                break;
        default:
                return (EINVAL);
        }

        inp = so->so_pcb;
        INP_WLOCK_ASSERT(inp);
        SOCKBUF_LOCK(&so->so_snd);
        tls = so->so_snd.sb_tls_info;
        if (tls == NULL) {
                SOCKBUF_UNLOCK(&so->so_snd);
                return (0);
        }

        if (tls->mode == mode) {
                SOCKBUF_UNLOCK(&so->so_snd);
                return (0);
        }

        tls = ktls_hold(tls);
        SOCKBUF_UNLOCK(&so->so_snd);
        INP_WUNLOCK(inp);

        tls_new = ktls_clone_session(tls);

        if (mode == TCP_TLS_MODE_IFNET)
                error = ktls_try_ifnet(so, tls_new, true);
        else
                error = ktls_try_sw(so, tls_new, KTLS_TX);
        if (error) {
                counter_u64_add(ktls_switch_failed, 1);
                ktls_free(tls_new);
                ktls_free(tls);
                INP_WLOCK(inp);
                return (error);
        }

        error = SOCK_IO_SEND_LOCK(so, SBL_WAIT);
        if (error) {
                counter_u64_add(ktls_switch_failed, 1);
                ktls_free(tls_new);
                ktls_free(tls);
                INP_WLOCK(inp);
                return (error);
        }

        /*
         * If we raced with another session change, keep the existing
         * session.
         */
        if (tls != so->so_snd.sb_tls_info) {
                counter_u64_add(ktls_switch_failed, 1);
                SOCK_IO_SEND_UNLOCK(so);
                ktls_free(tls_new);
                ktls_free(tls);
                INP_WLOCK(inp);
                return (EBUSY);
        }

        INP_WLOCK(inp);
        SOCKBUF_LOCK(&so->so_snd);
        so->so_snd.sb_tls_info = tls_new;
        if (tls_new->mode != TCP_TLS_MODE_SW)
                so->so_snd.sb_flags |= SB_TLS_IFNET;
        SOCKBUF_UNLOCK(&so->so_snd);
        SOCK_IO_SEND_UNLOCK(so);

        /*
         * Drop two references on 'tls'.  The first is for the
         * ktls_hold() above.  The second drops the reference from the
         * socket buffer.
         */
        KASSERT(tls->refcount >= 2, ("too few references on old session"));
        ktls_free(tls);
        ktls_free(tls);

        if (mode == TCP_TLS_MODE_IFNET)
                counter_u64_add(ktls_switch_to_ifnet, 1);
        else
                counter_u64_add(ktls_switch_to_sw, 1);

        return (0);
}

/*
 * Try to allocate a new TLS send tag.  This task is scheduled when
 * ip_output detects a route change while trying to transmit a packet
 * holding a TLS record.  If a new tag is allocated, replace the tag
 * in the TLS session.  Subsequent packets on the connection will use
 * the new tag.  If a new tag cannot be allocated, drop the
 * connection.
 */
static void
ktls_reset_send_tag(void *context, int pending)
{
        struct epoch_tracker et;
        struct ktls_session *tls;
        struct m_snd_tag *old, *new;
        struct inpcb *inp;
        struct tcpcb *tp;
        int error;

        MPASS(pending == 1);

        tls = context;
        inp = tls->inp;

        /*
         * Free the old tag first before allocating a new one.
         * ip[6]_output_send() will treat a NULL send tag the same as
         * an ifp mismatch and drop packets until a new tag is
         * allocated.
         *
         * Write-lock the INP when changing tls->snd_tag since
         * ip[6]_output_send() holds a read-lock when reading the
         * pointer.
         */
        INP_WLOCK(inp);
        old = tls->snd_tag;
        tls->snd_tag = NULL;
        INP_WUNLOCK(inp);
        if (old != NULL)
                m_snd_tag_rele(old);

        error = ktls_alloc_snd_tag(inp, tls, true, &new);

        if (error == 0) {
                INP_WLOCK(inp);
                tls->snd_tag = new;
                mtx_pool_lock(mtxpool_sleep, tls);
                tls->reset_pending = false;
                mtx_pool_unlock(mtxpool_sleep, tls);
                if (!in_pcbrele_wlocked(inp))
                        INP_WUNLOCK(inp);

                counter_u64_add(ktls_ifnet_reset, 1);

                /*
                 * XXX: Should we kick tcp_output explicitly now that
                 * the send tag is fixed or just rely on timers?
                 */
        } else {
                NET_EPOCH_ENTER(et);
                INP_WLOCK(inp);
                if (!in_pcbrele_wlocked(inp)) {
                        if (!(inp->inp_flags & INP_TIMEWAIT) &&
                            !(inp->inp_flags & INP_DROPPED)) {
                                tp = intotcpcb(inp);
                                CURVNET_SET(tp->t_vnet);
                                tp = tcp_drop(tp, ECONNABORTED);
                                CURVNET_RESTORE();
                                if (tp != NULL)
                                        INP_WUNLOCK(inp);
                                counter_u64_add(ktls_ifnet_reset_dropped, 1);
                        } else
                                INP_WUNLOCK(inp);
                }
                NET_EPOCH_EXIT(et);

                counter_u64_add(ktls_ifnet_reset_failed, 1);

                /*
                 * Leave reset_pending true to avoid future tasks while
                 * the socket goes away.
                 */
        }

        ktls_free(tls);
}

int
ktls_output_eagain(struct inpcb *inp, struct ktls_session *tls)
{

        if (inp == NULL)
                return (ENOBUFS);

        INP_LOCK_ASSERT(inp);

        /*
         * See if we should schedule a task to update the send tag for
         * this session.
         */
        mtx_pool_lock(mtxpool_sleep, tls);
        if (!tls->reset_pending) {
                (void) ktls_hold(tls);
                in_pcbref(inp);
                tls->inp = inp;
                tls->reset_pending = true;
                taskqueue_enqueue(taskqueue_thread, &tls->reset_tag_task);
        }
        mtx_pool_unlock(mtxpool_sleep, tls);
        return (ENOBUFS);
}

#ifdef RATELIMIT
int
ktls_modify_txrtlmt(struct ktls_session *tls, uint64_t max_pacing_rate)
{
        union if_snd_tag_modify_params params = {
                .rate_limit.max_rate = max_pacing_rate,
                .rate_limit.flags = M_NOWAIT,
        };
        struct m_snd_tag *mst;
        struct ifnet *ifp;
        int error;

        /* Can't get to the inp, but it should be locked. */
        /* INP_LOCK_ASSERT(inp); */

        MPASS(tls->mode == TCP_TLS_MODE_IFNET);

        if (tls->snd_tag == NULL) {
                /*
                 * Resetting send tag, ignore this change.  The
                 * pending reset may or may not see this updated rate
                 * in the tcpcb.  If it doesn't, we will just lose
                 * this rate change.
                 */
                return (0);
        }

        mst = tls->snd_tag;

        MPASS(mst != NULL);
        MPASS(mst->type == IF_SND_TAG_TYPE_TLS_RATE_LIMIT);

        ifp = mst->ifp;
        return (ifp->if_snd_tag_modify(mst, &params));
}
#endif
#endif

void
ktls_destroy(struct ktls_session *tls)
{
        struct rm_priotracker prio;

        if (tls->sequential_records) {
                struct mbuf *m, *n;
                int page_count;

                STAILQ_FOREACH_SAFE(m, &tls->pending_records, m_epg_stailq, n) {
                        page_count = m->m_epg_enc_cnt;
                        while (page_count > 0) {
                                KASSERT(page_count >= m->m_epg_nrdy,
                                    ("%s: too few pages", __func__));
                                page_count -= m->m_epg_nrdy;
                                m = m_free(m);
                        }
                }
        }
        ktls_cleanup(tls);
        if (tls->be != NULL && ktls_allow_unload) {
                rm_rlock(&ktls_backends_lock, &prio);
                tls->be->use_count--;
                rm_runlock(&ktls_backends_lock, &prio);
        }
        uma_zfree(ktls_session_zone, tls);
}

void
ktls_seq(struct sockbuf *sb, struct mbuf *m)
{

        for (; m != NULL; m = m->m_next) {
                KASSERT((m->m_flags & M_EXTPG) != 0,
                    ("ktls_seq: mapped mbuf %p", m));

                m->m_epg_seqno = sb->sb_tls_seqno;
                sb->sb_tls_seqno++;
        }
}

/*
 * Add TLS framing (headers and trailers) to a chain of mbufs.  Each
 * mbuf in the chain must be an unmapped mbuf.  The payload of the
 * mbuf must be populated with the payload of each TLS record.
 *
 * The record_type argument specifies the TLS record type used when
 * populating the TLS header.
 *
 * The enq_count argument on return is set to the number of pages of
 * payload data for this entire chain that need to be encrypted via SW
 * encryption.  The returned value should be passed to ktls_enqueue
 * when scheduling encryption of this chain of mbufs.  To handle the
 * special case of empty fragments for TLS 1.0 sessions, an empty
 * fragment counts as one page.
 */
void
ktls_frame(struct mbuf *top, struct ktls_session *tls, int *enq_cnt,
    uint8_t record_type)
{
        struct tls_record_layer *tlshdr;
        struct mbuf *m;
        uint64_t *noncep;
        uint16_t tls_len;
        int maxlen;

        maxlen = tls->params.max_frame_len;
        *enq_cnt = 0;
        for (m = top; m != NULL; m = m->m_next) {
                /*
                 * All mbufs in the chain should be TLS records whose
                 * payload does not exceed the maximum frame length.
                 *
                 * Empty TLS 1.0 records are permitted when using CBC.
                 */
                KASSERT(m->m_len <= maxlen && m->m_len >= 0 &&
                    (m->m_len > 0 || ktls_permit_empty_frames(tls)),
                    ("ktls_frame: m %p len %d", m, m->m_len));

                /*
                 * TLS frames require unmapped mbufs to store session
                 * info.
                 */
                KASSERT((m->m_flags & M_EXTPG) != 0,
                    ("ktls_frame: mapped mbuf %p (top = %p)", m, top));

                tls_len = m->m_len;

                /* Save a reference to the session. */
                m->m_epg_tls = ktls_hold(tls);

                m->m_epg_hdrlen = tls->params.tls_hlen;
                m->m_epg_trllen = tls->params.tls_tlen;
                if (tls->params.cipher_algorithm == CRYPTO_AES_CBC) {
                        int bs, delta;

                        /*
                         * AES-CBC pads messages to a multiple of the
                         * block size.  Note that the padding is
                         * applied after the digest and the encryption
                         * is done on the "plaintext || mac || padding".
                         * At least one byte of padding is always
                         * present.
                         *
                         * Compute the final trailer length assuming
                         * at most one block of padding.
                         * tls->params.sb_tls_tlen is the maximum
                         * possible trailer length (padding + digest).
                         * delta holds the number of excess padding
                         * bytes if the maximum were used.  Those
                         * extra bytes are removed.
                         */
                        bs = tls->params.tls_bs;
                        delta = (tls_len + tls->params.tls_tlen) & (bs - 1);
                        m->m_epg_trllen -= delta;
                }
                m->m_len += m->m_epg_hdrlen + m->m_epg_trllen;

                /* Populate the TLS header. */
                tlshdr = (void *)m->m_epg_hdr;
                tlshdr->tls_vmajor = tls->params.tls_vmajor;

                /*
                 * TLS 1.3 masquarades as TLS 1.2 with a record type
                 * of TLS_RLTYPE_APP.
                 */
                if (tls->params.tls_vminor == TLS_MINOR_VER_THREE &&
                    tls->params.tls_vmajor == TLS_MAJOR_VER_ONE) {
                        tlshdr->tls_vminor = TLS_MINOR_VER_TWO;
                        tlshdr->tls_type = TLS_RLTYPE_APP;
                        /* save the real record type for later */
                        m->m_epg_record_type = record_type;
                        m->m_epg_trail[0] = record_type;
                } else {
                        tlshdr->tls_vminor = tls->params.tls_vminor;
                        tlshdr->tls_type = record_type;
                }
                tlshdr->tls_length = htons(m->m_len - sizeof(*tlshdr));

                /*
                 * Store nonces / explicit IVs after the end of the
                 * TLS header.
                 *
                 * For GCM with TLS 1.2, an 8 byte nonce is copied
                 * from the end of the IV.  The nonce is then
                 * incremented for use by the next record.
                 *
                 * For CBC, a random nonce is inserted for TLS 1.1+.
                 */
                if (tls->params.cipher_algorithm == CRYPTO_AES_NIST_GCM_16 &&
                    tls->params.tls_vminor == TLS_MINOR_VER_TWO) {
                        noncep = (uint64_t *)(tls->params.iv + 8);
                        be64enc(tlshdr + 1, *noncep);
                        (*noncep)++;
                } else if (tls->params.cipher_algorithm == CRYPTO_AES_CBC &&
                    tls->params.tls_vminor >= TLS_MINOR_VER_ONE)
                        arc4rand(tlshdr + 1, AES_BLOCK_LEN, 0);

                /*
                 * When using SW encryption, mark the mbuf not ready.
                 * It will be marked ready via sbready() after the
                 * record has been encrypted.
                 *
                 * When using ifnet TLS, unencrypted TLS records are
                 * sent down the stack to the NIC.
                 */
                if (tls->mode == TCP_TLS_MODE_SW) {
                        m->m_flags |= M_NOTREADY;
                        if (__predict_false(tls_len == 0)) {
                                /* TLS 1.0 empty fragment. */
                                m->m_epg_nrdy = 1;
                        } else
                                m->m_epg_nrdy = m->m_epg_npgs;
                        *enq_cnt += m->m_epg_nrdy;
                }
        }
}

bool
ktls_permit_empty_frames(struct ktls_session *tls)
{
        return (tls->params.cipher_algorithm == CRYPTO_AES_CBC &&
            tls->params.tls_vminor == TLS_MINOR_VER_ZERO);
}

void
ktls_check_rx(struct sockbuf *sb)
{
        struct tls_record_layer hdr;
        struct ktls_wq *wq;
        struct socket *so;
        bool running;

        SOCKBUF_LOCK_ASSERT(sb);
        KASSERT(sb->sb_flags & SB_TLS_RX, ("%s: sockbuf %p isn't TLS RX",
            __func__, sb));
        so = __containerof(sb, struct socket, so_rcv);

        if (sb->sb_flags & SB_TLS_RX_RUNNING)
                return;

        /* Is there enough queued for a TLS header? */
        if (sb->sb_tlscc < sizeof(hdr)) {
                if ((sb->sb_state & SBS_CANTRCVMORE) != 0 && sb->sb_tlscc != 0)
                        so->so_error = EMSGSIZE;
                return;
        }

        m_copydata(sb->sb_mtls, 0, sizeof(hdr), (void *)&hdr);

        /* Is the entire record queued? */
        if (sb->sb_tlscc < sizeof(hdr) + ntohs(hdr.tls_length)) {
                if ((sb->sb_state & SBS_CANTRCVMORE) != 0)
                        so->so_error = EMSGSIZE;
                return;
        }

        sb->sb_flags |= SB_TLS_RX_RUNNING;

        soref(so);
        wq = &ktls_wq[so->so_rcv.sb_tls_info->wq_index];
        mtx_lock(&wq->mtx);
        STAILQ_INSERT_TAIL(&wq->so_head, so, so_ktls_rx_list);
        running = wq->running;
        mtx_unlock(&wq->mtx);
        if (!running)
                wakeup(wq);
        counter_u64_add(ktls_cnt_rx_queued, 1);
}

static struct mbuf *
ktls_detach_record(struct sockbuf *sb, int len)
{
        struct mbuf *m, *n, *top;
        int remain;

        SOCKBUF_LOCK_ASSERT(sb);
        MPASS(len <= sb->sb_tlscc);

        /*
         * If TLS chain is the exact size of the record,
         * just grab the whole record.
         */
        top = sb->sb_mtls;
        if (sb->sb_tlscc == len) {
                sb->sb_mtls = NULL;
                sb->sb_mtlstail = NULL;
                goto out;
        }

        /*
         * While it would be nice to use m_split() here, we need
         * to know exactly what m_split() allocates to update the
         * accounting, so do it inline instead.
         */
        remain = len;
        for (m = top; remain > m->m_len; m = m->m_next)
                remain -= m->m_len;

        /* Easy case: don't have to split 'm'. */
        if (remain == m->m_len) {
                sb->sb_mtls = m->m_next;
                if (sb->sb_mtls == NULL)
                        sb->sb_mtlstail = NULL;
                m->m_next = NULL;
                goto out;
        }

        /*
         * Need to allocate an mbuf to hold the remainder of 'm'.  Try
         * with M_NOWAIT first.
         */
        n = m_get(M_NOWAIT, MT_DATA);
        if (n == NULL) {
                /*
                 * Use M_WAITOK with socket buffer unlocked.  If
                 * 'sb_mtls' changes while the lock is dropped, return
                 * NULL to force the caller to retry.
                 */
                SOCKBUF_UNLOCK(sb);

                n = m_get(M_WAITOK, MT_DATA);

                SOCKBUF_LOCK(sb);
                if (sb->sb_mtls != top) {
                        m_free(n);
                        return (NULL);
                }
        }
        n->m_flags |= M_NOTREADY;

        /* Store remainder in 'n'. */
        n->m_len = m->m_len - remain;
        if (m->m_flags & M_EXT) {
                n->m_data = m->m_data + remain;
                mb_dupcl(n, m);
        } else {
                bcopy(mtod(m, caddr_t) + remain, mtod(n, caddr_t), n->m_len);
        }

        /* Trim 'm' and update accounting. */
        m->m_len -= n->m_len;
        sb->sb_tlscc -= n->m_len;
        sb->sb_ccc -= n->m_len;

        /* Account for 'n'. */
        sballoc_ktls_rx(sb, n);

        /* Insert 'n' into the TLS chain. */
        sb->sb_mtls = n;
        n->m_next = m->m_next;
        if (sb->sb_mtlstail == m)
                sb->sb_mtlstail = n;

        /* Detach the record from the TLS chain. */
        m->m_next = NULL;

out:
        MPASS(m_length(top, NULL) == len);
        for (m = top; m != NULL; m = m->m_next)
                sbfree_ktls_rx(sb, m);
        sb->sb_tlsdcc = len;
        sb->sb_ccc += len;
        SBCHECK(sb);
        return (top);
}

/*
 * Determine the length of the trailing zero padding and find the real
 * record type in the byte before the padding.
 *
 * Walking the mbuf chain backwards is clumsy, so another option would
 * be to scan forwards remembering the last non-zero byte before the
 * trailer.  However, it would be expensive to scan the entire record.
 * Instead, find the last non-zero byte of each mbuf in the chain
 * keeping track of the relative offset of that nonzero byte.
 *
 * trail_len is the size of the MAC/tag on input and is set to the
 * size of the full trailer including padding and the record type on
 * return.
 */
static int
tls13_find_record_type(struct ktls_session *tls, struct mbuf *m, int tls_len,
    int *trailer_len, uint8_t *record_typep)
{
        char *cp;
        u_int digest_start, last_offset, m_len, offset;
        uint8_t record_type;

        digest_start = tls_len - *trailer_len;
        last_offset = 0;
        offset = 0;
        for (; m != NULL && offset < digest_start;
             offset += m->m_len, m = m->m_next) {
                /* Don't look for padding in the tag. */
                m_len = min(digest_start - offset, m->m_len);
                cp = mtod(m, char *);

                /* Find last non-zero byte in this mbuf. */
                while (m_len > 0 && cp[m_len - 1] == 0)
                        m_len--;
                if (m_len > 0) {
                        record_type = cp[m_len - 1];
                        last_offset = offset + m_len;
                }
        }
        if (last_offset < tls->params.tls_hlen)
                return (EBADMSG);

        *record_typep = record_type;
        *trailer_len = tls_len - last_offset + 1;
        return (0);
}

static void
ktls_drop(struct socket *so, int error)
{
        struct epoch_tracker et;
        struct inpcb *inp = sotoinpcb(so);
        struct tcpcb *tp;

        NET_EPOCH_ENTER(et);
        INP_WLOCK(inp);
        if (!(inp->inp_flags & INP_DROPPED)) {
                tp = intotcpcb(inp);
                CURVNET_SET(inp->inp_vnet);
                tp = tcp_drop(tp, error);
                CURVNET_RESTORE();
                if (tp != NULL)
                        INP_WUNLOCK(inp);
        } else
                INP_WUNLOCK(inp);
        NET_EPOCH_EXIT(et);
}

static void
ktls_decrypt(struct socket *so)
{
        char tls_header[MBUF_PEXT_HDR_LEN];
        struct ktls_session *tls;
        struct sockbuf *sb;
        struct tls_record_layer *hdr;
        struct tls_get_record tgr;
        struct mbuf *control, *data, *m;
        uint64_t seqno;
        int error, remain, tls_len, trail_len;
        bool tls13;
        uint8_t vminor, record_type;

        hdr = (struct tls_record_layer *)tls_header;
        sb = &so->so_rcv;
        SOCKBUF_LOCK(sb);
        KASSERT(sb->sb_flags & SB_TLS_RX_RUNNING,
            ("%s: socket %p not running", __func__, so));

        tls = sb->sb_tls_info;
        MPASS(tls != NULL);

        tls13 = (tls->params.tls_vminor == TLS_MINOR_VER_THREE);
        if (tls13)
                vminor = TLS_MINOR_VER_TWO;
        else
                vminor = tls->params.tls_vminor;
        for (;;) {
                /* Is there enough queued for a TLS header? */
                if (sb->sb_tlscc < tls->params.tls_hlen)
                        break;

                m_copydata(sb->sb_mtls, 0, tls->params.tls_hlen, tls_header);
                tls_len = sizeof(*hdr) + ntohs(hdr->tls_length);

                if (hdr->tls_vmajor != tls->params.tls_vmajor ||
                    hdr->tls_vminor != vminor)
                        error = EINVAL;
                else if (tls13 && hdr->tls_type != TLS_RLTYPE_APP)
                        error = EINVAL;
                else if (tls_len < tls->params.tls_hlen || tls_len >
                    tls->params.tls_hlen + TLS_MAX_MSG_SIZE_V10_2 +
                    tls->params.tls_tlen)
                        error = EMSGSIZE;
                else
                        error = 0;
                if (__predict_false(error != 0)) {
                        /*
                         * We have a corrupted record and are likely
                         * out of sync.  The connection isn't
                         * recoverable at this point, so abort it.
                         */
                        SOCKBUF_UNLOCK(sb);
                        counter_u64_add(ktls_offload_corrupted_records, 1);

                        ktls_drop(so, error);
                        goto deref;
                }

                /* Is the entire record queued? */
                if (sb->sb_tlscc < tls_len)
                        break;

                /*
                 * Split out the portion of the mbuf chain containing
                 * this TLS record.
                 */
                data = ktls_detach_record(sb, tls_len);
                if (data == NULL)
                        continue;
                MPASS(sb->sb_tlsdcc == tls_len);

                seqno = sb->sb_tls_seqno;
                sb->sb_tls_seqno++;
                SBCHECK(sb);
                SOCKBUF_UNLOCK(sb);

                error = tls->sw_decrypt(tls, hdr, data, seqno, &trail_len);
                if (error == 0) {
                        if (tls13)
                                error = tls13_find_record_type(tls, data,
                                    tls_len, &trail_len, &record_type);
                        else
                                record_type = hdr->tls_type;
                }
                if (error) {
                        counter_u64_add(ktls_offload_failed_crypto, 1);

                        SOCKBUF_LOCK(sb);
                        if (sb->sb_tlsdcc == 0) {
                                /*
                                 * sbcut/drop/flush discarded these
                                 * mbufs.
                                 */
                                m_freem(data);
                                break;
                        }

                        /*
                         * Drop this TLS record's data, but keep
                         * decrypting subsequent records.
                         */
                        sb->sb_ccc -= tls_len;
                        sb->sb_tlsdcc = 0;

                        CURVNET_SET(so->so_vnet);
                        so->so_error = EBADMSG;
                        sorwakeup_locked(so);
                        CURVNET_RESTORE();

                        m_freem(data);

                        SOCKBUF_LOCK(sb);
                        continue;
                }

                /* Allocate the control mbuf. */
                memset(&tgr, 0, sizeof(tgr));
                tgr.tls_type = record_type;
                tgr.tls_vmajor = hdr->tls_vmajor;
                tgr.tls_vminor = hdr->tls_vminor;
                tgr.tls_length = htobe16(tls_len - tls->params.tls_hlen -
                    trail_len);
                control = sbcreatecontrol_how(&tgr, sizeof(tgr),
                    TLS_GET_RECORD, IPPROTO_TCP, M_WAITOK);

                SOCKBUF_LOCK(sb);
                if (sb->sb_tlsdcc == 0) {
                        /* sbcut/drop/flush discarded these mbufs. */
                        MPASS(sb->sb_tlscc == 0);
                        m_freem(data);
                        m_freem(control);
                        break;
                }

                /*
                 * Clear the 'dcc' accounting in preparation for
                 * adding the decrypted record.
                 */
                sb->sb_ccc -= tls_len;
                sb->sb_tlsdcc = 0;
                SBCHECK(sb);

                /* If there is no payload, drop all of the data. */
                if (tgr.tls_length == htobe16(0)) {
                        m_freem(data);
                        data = NULL;
                } else {
                        /* Trim header. */
                        remain = tls->params.tls_hlen;
                        while (remain > 0) {
                                if (data->m_len > remain) {
                                        data->m_data += remain;
                                        data->m_len -= remain;
                                        break;
                                }
                                remain -= data->m_len;
                                data = m_free(data);
                        }

                        /* Trim trailer and clear M_NOTREADY. */
                        remain = be16toh(tgr.tls_length);
                        m = data;
                        for (m = data; remain > m->m_len; m = m->m_next) {
                                m->m_flags &= ~M_NOTREADY;
                                remain -= m->m_len;
                        }
                        m->m_len = remain;
                        m_freem(m->m_next);
                        m->m_next = NULL;
                        m->m_flags &= ~M_NOTREADY;

                        /* Set EOR on the final mbuf. */
                        m->m_flags |= M_EOR;
                }

                sbappendcontrol_locked(sb, data, control, 0);
        }

        sb->sb_flags &= ~SB_TLS_RX_RUNNING;

        if ((sb->sb_state & SBS_CANTRCVMORE) != 0 && sb->sb_tlscc > 0)
                so->so_error = EMSGSIZE;

        sorwakeup_locked(so);

deref:
        SOCKBUF_UNLOCK_ASSERT(sb);

        CURVNET_SET(so->so_vnet);
        SOCK_LOCK(so);
        sorele(so);
        CURVNET_RESTORE();
}

void
ktls_enqueue_to_free(struct mbuf *m)
{
        struct ktls_wq *wq;
        bool running;

        /* Mark it for freeing. */
        m->m_epg_flags |= EPG_FLAG_2FREE;
        wq = &ktls_wq[m->m_epg_tls->wq_index];
        mtx_lock(&wq->mtx);
        STAILQ_INSERT_TAIL(&wq->m_head, m, m_epg_stailq);
        running = wq->running;
        mtx_unlock(&wq->mtx);
        if (!running)
                wakeup(wq);
}

/* Number of TLS records in a batch passed to ktls_enqueue(). */
static u_int
ktls_batched_records(struct mbuf *m)
{
        int page_count, records;

        records = 0;
        page_count = m->m_epg_enc_cnt;
        while (page_count > 0) {
                records++;
                page_count -= m->m_epg_nrdy;
                m = m->m_next;
        }
        KASSERT(page_count == 0, ("%s: mismatched page count", __func__));
        return (records);
}

void
ktls_enqueue(struct mbuf *m, struct socket *so, int page_count)
{
        struct ktls_session *tls;
        struct ktls_wq *wq;
        int queued;
        bool running;

        KASSERT(((m->m_flags & (M_EXTPG | M_NOTREADY)) ==
            (M_EXTPG | M_NOTREADY)),
            ("ktls_enqueue: %p not unready & nomap mbuf\n", m));
        KASSERT(page_count != 0, ("enqueueing TLS mbuf with zero page count"));

        KASSERT(m->m_epg_tls->mode == TCP_TLS_MODE_SW, ("!SW TLS mbuf"));

        m->m_epg_enc_cnt = page_count;

        /*
         * Save a pointer to the socket.  The caller is responsible
         * for taking an additional reference via soref().
         */
        m->m_epg_so = so;

        queued = 1;
        tls = m->m_epg_tls;
        wq = &ktls_wq[tls->wq_index];
        mtx_lock(&wq->mtx);
        if (__predict_false(tls->sequential_records)) {
                /*
                 * For TLS 1.0, records must be encrypted
                 * sequentially.  For a given connection, all records
                 * queued to the associated work queue are processed
                 * sequentially.  However, sendfile(2) might complete
                 * I/O requests spanning multiple TLS records out of
                 * order.  Here we ensure TLS records are enqueued to
                 * the work queue in FIFO order.
                 *
                 * tls->next_seqno holds the sequence number of the
                 * next TLS record that should be enqueued to the work
                 * queue.  If this next record is not tls->next_seqno,
                 * it must be a future record, so insert it, sorted by
                 * TLS sequence number, into tls->pending_records and
                 * return.
                 *
                 * If this TLS record matches tls->next_seqno, place
                 * it in the work queue and then check
                 * tls->pending_records to see if any
                 * previously-queued records are now ready for
                 * encryption.
                 */
                if (m->m_epg_seqno != tls->next_seqno) {
                        struct mbuf *n, *p;

                        p = NULL;
                        STAILQ_FOREACH(n, &tls->pending_records, m_epg_stailq) {
                                if (n->m_epg_seqno > m->m_epg_seqno)
                                        break;
                                p = n;
                        }
                        if (n == NULL)
                                STAILQ_INSERT_TAIL(&tls->pending_records, m,
                                    m_epg_stailq);
                        else if (p == NULL)
                                STAILQ_INSERT_HEAD(&tls->pending_records, m,
                                    m_epg_stailq);
                        else
                                STAILQ_INSERT_AFTER(&tls->pending_records, p, m,
                                    m_epg_stailq);
                        mtx_unlock(&wq->mtx);
                        counter_u64_add(ktls_cnt_tx_pending, 1);
                        return;
                }

                tls->next_seqno += ktls_batched_records(m);
                STAILQ_INSERT_TAIL(&wq->m_head, m, m_epg_stailq);

                while (!STAILQ_EMPTY(&tls->pending_records)) {
                        struct mbuf *n;

                        n = STAILQ_FIRST(&tls->pending_records);
                        if (n->m_epg_seqno != tls->next_seqno)
                                break;

                        queued++;
                        STAILQ_REMOVE_HEAD(&tls->pending_records, m_epg_stailq);
                        tls->next_seqno += ktls_batched_records(n);
                        STAILQ_INSERT_TAIL(&wq->m_head, n, m_epg_stailq);
                }
                counter_u64_add(ktls_cnt_tx_pending, -(queued - 1));
        } else
                STAILQ_INSERT_TAIL(&wq->m_head, m, m_epg_stailq);

        running = wq->running;
        mtx_unlock(&wq->mtx);
        if (!running)
                wakeup(wq);
        counter_u64_add(ktls_cnt_tx_queued, queued);
}

static __noinline void
ktls_encrypt(struct mbuf *top)
{
        struct ktls_session *tls;
        struct socket *so;
        struct mbuf *m;
        vm_paddr_t parray[1 + btoc(TLS_MAX_MSG_SIZE_V10_2)];
        struct iovec src_iov[1 + btoc(TLS_MAX_MSG_SIZE_V10_2)];
        struct iovec dst_iov[1 + btoc(TLS_MAX_MSG_SIZE_V10_2)];
        vm_page_t pg;
        int error, i, len, npages, off, total_pages;
        bool is_anon;

        so = top->m_epg_so;
        tls = top->m_epg_tls;
        KASSERT(tls != NULL, ("tls = NULL, top = %p\n", top));
        KASSERT(so != NULL, ("so = NULL, top = %p\n", top));
#ifdef INVARIANTS
        top->m_epg_so = NULL;
#endif
        total_pages = top->m_epg_enc_cnt;
        npages = 0;

        /*
         * Encrypt the TLS records in the chain of mbufs starting with
         * 'top'.  'total_pages' gives us a total count of pages and is
         * used to know when we have finished encrypting the TLS
         * records originally queued with 'top'.
         *
         * NB: These mbufs are queued in the socket buffer and
         * 'm_next' is traversing the mbufs in the socket buffer.  The
         * socket buffer lock is not held while traversing this chain.
         * Since the mbufs are all marked M_NOTREADY their 'm_next'
         * pointers should be stable.  However, the 'm_next' of the
         * last mbuf encrypted is not necessarily NULL.  It can point
         * to other mbufs appended while 'top' was on the TLS work
         * queue.
         *
         * Each mbuf holds an entire TLS record.
         */
        error = 0;
        for (m = top; npages != total_pages; m = m->m_next) {
                KASSERT(m->m_epg_tls == tls,
                    ("different TLS sessions in a single mbuf chain: %p vs %p",
                    tls, m->m_epg_tls));
                KASSERT((m->m_flags & (M_EXTPG | M_NOTREADY)) ==
                    (M_EXTPG | M_NOTREADY),
                    ("%p not unready & nomap mbuf (top = %p)\n", m, top));
                KASSERT(npages + m->m_epg_npgs <= total_pages,
                    ("page count mismatch: top %p, total_pages %d, m %p", top,
                    total_pages, m));

                /*
                 * Generate source and destination ivoecs to pass to
                 * the SW encryption backend.  For writable mbufs, the
                 * destination iovec is a copy of the source and
                 * encryption is done in place.  For file-backed mbufs
                 * (from sendfile), anonymous wired pages are
                 * allocated and assigned to the destination iovec.
                 */
                is_anon = (m->m_epg_flags & EPG_FLAG_ANON) != 0;

                off = m->m_epg_1st_off;
                for (i = 0; i < m->m_epg_npgs; i++, off = 0) {
                        len = m_epg_pagelen(m, i, off);
                        src_iov[i].iov_len = len;
                        src_iov[i].iov_base =
                            (char *)(void *)PHYS_TO_DMAP(m->m_epg_pa[i]) +
                                off;

                        if (is_anon) {
                                dst_iov[i].iov_base = src_iov[i].iov_base;
                                dst_iov[i].iov_len = src_iov[i].iov_len;
                                continue;
                        }
retry_page:
                        pg = vm_page_alloc_noobj(VM_ALLOC_NODUMP |
                            VM_ALLOC_WIRED);
                        if (pg == NULL) {
                                vm_wait(NULL);
                                goto retry_page;
                        }
                        parray[i] = VM_PAGE_TO_PHYS(pg);
                        dst_iov[i].iov_base =
                            (char *)(void *)PHYS_TO_DMAP(parray[i]) + off;
                        dst_iov[i].iov_len = len;
                }

                npages += m->m_epg_nrdy;

                error = (*tls->sw_encrypt)(tls,
                    (const struct tls_record_layer *)m->m_epg_hdr,
                    m->m_epg_trail, src_iov, dst_iov, i, m->m_epg_seqno,
                    m->m_epg_record_type);
                if (error) {
                        counter_u64_add(ktls_offload_failed_crypto, 1);
                        break;
                }

                /*
                 * For file-backed mbufs, release the file-backed
                 * pages and replace them in the ext_pgs array with
                 * the anonymous wired pages allocated above.
                 */
                if (!is_anon) {
                        /* Free the old pages. */
                        m->m_ext.ext_free(m);

                        /* Replace them with the new pages. */
                        for (i = 0; i < m->m_epg_npgs; i++)
                                m->m_epg_pa[i] = parray[i];

                        /* Use the basic free routine. */
                        m->m_ext.ext_free = mb_free_mext_pgs;

                        /* Pages are now writable. */
                        m->m_epg_flags |= EPG_FLAG_ANON;
                }

                /*
                 * Drop a reference to the session now that it is no
                 * longer needed.  Existing code depends on encrypted
                 * records having no associated session vs
                 * yet-to-be-encrypted records having an associated
                 * session.
                 */
                m->m_epg_tls = NULL;
                ktls_free(tls);
        }

        CURVNET_SET(so->so_vnet);
        if (error == 0) {
                (void)(*so->so_proto->pr_usrreqs->pru_ready)(so, top, npages);
        } else {
                ktls_drop(so, EIO);
                mb_free_notready(top, total_pages);
        }

        SOCK_LOCK(so);
        sorele(so);
        CURVNET_RESTORE();
}

static void
ktls_work_thread(void *ctx)
{
        struct ktls_wq *wq = ctx;
        struct mbuf *m, *n;
        struct socket *so, *son;
        STAILQ_HEAD(, mbuf) local_m_head;
        STAILQ_HEAD(, socket) local_so_head;

        if (ktls_bind_threads > 1) {
                curthread->td_domain.dr_policy =
                        DOMAINSET_PREF(PCPU_GET(domain));
        }
#if defined(__aarch64__) || defined(__amd64__) || defined(__i386__)
        fpu_kern_thread(0);
#endif
        for (;;) {
                mtx_lock(&wq->mtx);
                while (STAILQ_EMPTY(&wq->m_head) &&
                    STAILQ_EMPTY(&wq->so_head)) {
                        wq->running = false;
                        mtx_sleep(wq, &wq->mtx, 0, "-", 0);
                        wq->running = true;
                }

                STAILQ_INIT(&local_m_head);
                STAILQ_CONCAT(&local_m_head, &wq->m_head);
                STAILQ_INIT(&local_so_head);
                STAILQ_CONCAT(&local_so_head, &wq->so_head);
                mtx_unlock(&wq->mtx);

                STAILQ_FOREACH_SAFE(m, &local_m_head, m_epg_stailq, n) {
                        if (m->m_epg_flags & EPG_FLAG_2FREE) {
                                ktls_free(m->m_epg_tls);
                                m_free_raw(m);
                        } else {
                                ktls_encrypt(m);
                                counter_u64_add(ktls_cnt_tx_queued, -1);
                        }
                }

                STAILQ_FOREACH_SAFE(so, &local_so_head, so_ktls_rx_list, son) {
                        ktls_decrypt(so);
                        counter_u64_add(ktls_cnt_rx_queued, -1);
                }
        }
}