Linux 5.7.7

[linux/fpc-iii.git] / net / tipc / crypto.c

// SPDX-License-Identifier: GPL-2.0
/**
 * net/tipc/crypto.c: TIPC crypto for key handling & packet en/decryption
 *
 * Copyright (c) 2019, Ericsson AB
 * All rights reserved.
 *
 * 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.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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 <crypto/aead.h>
#include <crypto/aes.h>
#include "crypto.h"

#define TIPC_TX_PROBE_LIM       msecs_to_jiffies(1000) /* > 1s */
#define TIPC_TX_LASTING_LIM     msecs_to_jiffies(120000) /* 2 mins */
#define TIPC_RX_ACTIVE_LIM      msecs_to_jiffies(3000) /* 3s */
#define TIPC_RX_PASSIVE_LIM     msecs_to_jiffies(180000) /* 3 mins */
#define TIPC_MAX_TFMS_DEF       10
#define TIPC_MAX_TFMS_LIM       1000

/**
 * TIPC Key ids
 */
enum {
        KEY_UNUSED = 0,
        KEY_MIN,
        KEY_1 = KEY_MIN,
        KEY_2,
        KEY_3,
        KEY_MAX = KEY_3,
};

/**
 * TIPC Crypto statistics
 */
enum {
        STAT_OK,
        STAT_NOK,
        STAT_ASYNC,
        STAT_ASYNC_OK,
        STAT_ASYNC_NOK,
        STAT_BADKEYS, /* tx only */
        STAT_BADMSGS = STAT_BADKEYS, /* rx only */
        STAT_NOKEYS,
        STAT_SWITCHES,

        MAX_STATS,
};

/* TIPC crypto statistics' header */
static const char *hstats[MAX_STATS] = {"ok", "nok", "async", "async_ok",
                                        "async_nok", "badmsgs", "nokeys",
                                        "switches"};

/* Max TFMs number per key */
int sysctl_tipc_max_tfms __read_mostly = TIPC_MAX_TFMS_DEF;

/**
 * struct tipc_key - TIPC keys' status indicator
 *
 *         7     6     5     4     3     2     1     0
 *      +-----+-----+-----+-----+-----+-----+-----+-----+
 * key: | (reserved)|passive idx| active idx|pending idx|
 *      +-----+-----+-----+-----+-----+-----+-----+-----+
 */
struct tipc_key {
#define KEY_BITS (2)
#define KEY_MASK ((1 << KEY_BITS) - 1)
        union {
                struct {
#if defined(__LITTLE_ENDIAN_BITFIELD)
                        u8 pending:2,
                           active:2,
                           passive:2, /* rx only */
                           reserved:2;
#elif defined(__BIG_ENDIAN_BITFIELD)
                        u8 reserved:2,
                           passive:2, /* rx only */
                           active:2,
                           pending:2;
#else
#error  "Please fix <asm/byteorder.h>"
#endif
                } __packed;
                u8 keys;
        };
};

/**
 * struct tipc_tfm - TIPC TFM structure to form a list of TFMs
 */
struct tipc_tfm {
        struct crypto_aead *tfm;
        struct list_head list;
};

/**
 * struct tipc_aead - TIPC AEAD key structure
 * @tfm_entry: per-cpu pointer to one entry in TFM list
 * @crypto: TIPC crypto owns this key
 * @cloned: reference to the source key in case cloning
 * @users: the number of the key users (TX/RX)
 * @salt: the key's SALT value
 * @authsize: authentication tag size (max = 16)
 * @mode: crypto mode is applied to the key
 * @hint[]: a hint for user key
 * @rcu: struct rcu_head
 * @seqno: the key seqno (cluster scope)
 * @refcnt: the key reference counter
 */
struct tipc_aead {
#define TIPC_AEAD_HINT_LEN (5)
        struct tipc_tfm * __percpu *tfm_entry;
        struct tipc_crypto *crypto;
        struct tipc_aead *cloned;
        atomic_t users;
        u32 salt;
        u8 authsize;
        u8 mode;
        char hint[TIPC_AEAD_HINT_LEN + 1];
        struct rcu_head rcu;

        atomic64_t seqno ____cacheline_aligned;
        refcount_t refcnt ____cacheline_aligned;

} ____cacheline_aligned;

/**
 * struct tipc_crypto_stats - TIPC Crypto statistics
 */
struct tipc_crypto_stats {
        unsigned int stat[MAX_STATS];
};

/**
 * struct tipc_crypto - TIPC TX/RX crypto structure
 * @net: struct net
 * @node: TIPC node (RX)
 * @aead: array of pointers to AEAD keys for encryption/decryption
 * @peer_rx_active: replicated peer RX active key index
 * @key: the key states
 * @working: the crypto is working or not
 * @stats: the crypto statistics
 * @sndnxt: the per-peer sndnxt (TX)
 * @timer1: general timer 1 (jiffies)
 * @timer2: general timer 1 (jiffies)
 * @lock: tipc_key lock
 */
struct tipc_crypto {
        struct net *net;
        struct tipc_node *node;
        struct tipc_aead __rcu *aead[KEY_MAX + 1]; /* key[0] is UNUSED */
        atomic_t peer_rx_active;
        struct tipc_key key;
        u8 working:1;
        struct tipc_crypto_stats __percpu *stats;

        atomic64_t sndnxt ____cacheline_aligned;
        unsigned long timer1;
        unsigned long timer2;
        spinlock_t lock; /* crypto lock */

} ____cacheline_aligned;

/* struct tipc_crypto_tx_ctx - TX context for callbacks */
struct tipc_crypto_tx_ctx {
        struct tipc_aead *aead;
        struct tipc_bearer *bearer;
        struct tipc_media_addr dst;
};

/* struct tipc_crypto_rx_ctx - RX context for callbacks */
struct tipc_crypto_rx_ctx {
        struct tipc_aead *aead;
        struct tipc_bearer *bearer;
};

static struct tipc_aead *tipc_aead_get(struct tipc_aead __rcu *aead);
static inline void tipc_aead_put(struct tipc_aead *aead);
static void tipc_aead_free(struct rcu_head *rp);
static int tipc_aead_users(struct tipc_aead __rcu *aead);
static void tipc_aead_users_inc(struct tipc_aead __rcu *aead, int lim);
static void tipc_aead_users_dec(struct tipc_aead __rcu *aead, int lim);
static void tipc_aead_users_set(struct tipc_aead __rcu *aead, int val);
static struct crypto_aead *tipc_aead_tfm_next(struct tipc_aead *aead);
static int tipc_aead_init(struct tipc_aead **aead, struct tipc_aead_key *ukey,
                          u8 mode);
static int tipc_aead_clone(struct tipc_aead **dst, struct tipc_aead *src);
static void *tipc_aead_mem_alloc(struct crypto_aead *tfm,
                                 unsigned int crypto_ctx_size,
                                 u8 **iv, struct aead_request **req,
                                 struct scatterlist **sg, int nsg);
static int tipc_aead_encrypt(struct tipc_aead *aead, struct sk_buff *skb,
                             struct tipc_bearer *b,
                             struct tipc_media_addr *dst,
                             struct tipc_node *__dnode);
static void tipc_aead_encrypt_done(struct crypto_async_request *base, int err);
static int tipc_aead_decrypt(struct net *net, struct tipc_aead *aead,
                             struct sk_buff *skb, struct tipc_bearer *b);
static void tipc_aead_decrypt_done(struct crypto_async_request *base, int err);
static inline int tipc_ehdr_size(struct tipc_ehdr *ehdr);
static int tipc_ehdr_build(struct net *net, struct tipc_aead *aead,
                           u8 tx_key, struct sk_buff *skb,
                           struct tipc_crypto *__rx);
static inline void tipc_crypto_key_set_state(struct tipc_crypto *c,
                                             u8 new_passive,
                                             u8 new_active,
                                             u8 new_pending);
static int tipc_crypto_key_attach(struct tipc_crypto *c,
                                  struct tipc_aead *aead, u8 pos);
static bool tipc_crypto_key_try_align(struct tipc_crypto *rx, u8 new_pending);
static struct tipc_aead *tipc_crypto_key_pick_tx(struct tipc_crypto *tx,
                                                 struct tipc_crypto *rx,
                                                 struct sk_buff *skb);
static void tipc_crypto_key_synch(struct tipc_crypto *rx, u8 new_rx_active,
                                  struct tipc_msg *hdr);
static int tipc_crypto_key_revoke(struct net *net, u8 tx_key);
static void tipc_crypto_rcv_complete(struct net *net, struct tipc_aead *aead,
                                     struct tipc_bearer *b,
                                     struct sk_buff **skb, int err);
static void tipc_crypto_do_cmd(struct net *net, int cmd);
static char *tipc_crypto_key_dump(struct tipc_crypto *c, char *buf);
#ifdef TIPC_CRYPTO_DEBUG
static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
                                  char *buf);
#endif

#define key_next(cur) ((cur) % KEY_MAX + 1)

#define tipc_aead_rcu_ptr(rcu_ptr, lock)                                \
        rcu_dereference_protected((rcu_ptr), lockdep_is_held(lock))

#define tipc_aead_rcu_replace(rcu_ptr, ptr, lock)                       \
do {                                                                    \
        typeof(rcu_ptr) __tmp = rcu_dereference_protected((rcu_ptr),    \
                                                lockdep_is_held(lock)); \
        rcu_assign_pointer((rcu_ptr), (ptr));                           \
        tipc_aead_put(__tmp);                                           \
} while (0)

#define tipc_crypto_key_detach(rcu_ptr, lock)                           \
        tipc_aead_rcu_replace((rcu_ptr), NULL, lock)

/**
 * tipc_aead_key_validate - Validate a AEAD user key
 */
int tipc_aead_key_validate(struct tipc_aead_key *ukey)
{
        int keylen;

        /* Check if algorithm exists */
        if (unlikely(!crypto_has_alg(ukey->alg_name, 0, 0))) {
                pr_info("Not found cipher: \"%s\"!\n", ukey->alg_name);
                return -ENODEV;
        }

        /* Currently, we only support the "gcm(aes)" cipher algorithm */
        if (strcmp(ukey->alg_name, "gcm(aes)"))
                return -ENOTSUPP;

        /* Check if key size is correct */
        keylen = ukey->keylen - TIPC_AES_GCM_SALT_SIZE;
        if (unlikely(keylen != TIPC_AES_GCM_KEY_SIZE_128 &&
                     keylen != TIPC_AES_GCM_KEY_SIZE_192 &&
                     keylen != TIPC_AES_GCM_KEY_SIZE_256))
                return -EINVAL;

        return 0;
}

static struct tipc_aead *tipc_aead_get(struct tipc_aead __rcu *aead)
{
        struct tipc_aead *tmp;

        rcu_read_lock();
        tmp = rcu_dereference(aead);
        if (unlikely(!tmp || !refcount_inc_not_zero(&tmp->refcnt)))
                tmp = NULL;
        rcu_read_unlock();

        return tmp;
}

static inline void tipc_aead_put(struct tipc_aead *aead)
{
        if (aead && refcount_dec_and_test(&aead->refcnt))
                call_rcu(&aead->rcu, tipc_aead_free);
}

/**
 * tipc_aead_free - Release AEAD key incl. all the TFMs in the list
 * @rp: rcu head pointer
 */
static void tipc_aead_free(struct rcu_head *rp)
{
        struct tipc_aead *aead = container_of(rp, struct tipc_aead, rcu);
        struct tipc_tfm *tfm_entry, *head, *tmp;

        if (aead->cloned) {
                tipc_aead_put(aead->cloned);
        } else {
                head = *this_cpu_ptr(aead->tfm_entry);
                list_for_each_entry_safe(tfm_entry, tmp, &head->list, list) {
                        crypto_free_aead(tfm_entry->tfm);
                        list_del(&tfm_entry->list);
                        kfree(tfm_entry);
                }
                /* Free the head */
                crypto_free_aead(head->tfm);
                list_del(&head->list);
                kfree(head);
        }
        free_percpu(aead->tfm_entry);
        kfree(aead);
}

static int tipc_aead_users(struct tipc_aead __rcu *aead)
{
        struct tipc_aead *tmp;
        int users = 0;

        rcu_read_lock();
        tmp = rcu_dereference(aead);
        if (tmp)
                users = atomic_read(&tmp->users);
        rcu_read_unlock();

        return users;
}

static void tipc_aead_users_inc(struct tipc_aead __rcu *aead, int lim)
{
        struct tipc_aead *tmp;

        rcu_read_lock();
        tmp = rcu_dereference(aead);
        if (tmp)
                atomic_add_unless(&tmp->users, 1, lim);
        rcu_read_unlock();
}

static void tipc_aead_users_dec(struct tipc_aead __rcu *aead, int lim)
{
        struct tipc_aead *tmp;

        rcu_read_lock();
        tmp = rcu_dereference(aead);
        if (tmp)
                atomic_add_unless(&rcu_dereference(aead)->users, -1, lim);
        rcu_read_unlock();
}

static void tipc_aead_users_set(struct tipc_aead __rcu *aead, int val)
{
        struct tipc_aead *tmp;
        int cur;

        rcu_read_lock();
        tmp = rcu_dereference(aead);
        if (tmp) {
                do {
                        cur = atomic_read(&tmp->users);
                        if (cur == val)
                                break;
                } while (atomic_cmpxchg(&tmp->users, cur, val) != cur);
        }
        rcu_read_unlock();
}

/**
 * tipc_aead_tfm_next - Move TFM entry to the next one in list and return it
 */
static struct crypto_aead *tipc_aead_tfm_next(struct tipc_aead *aead)
{
        struct tipc_tfm **tfm_entry = this_cpu_ptr(aead->tfm_entry);

        *tfm_entry = list_next_entry(*tfm_entry, list);
        return (*tfm_entry)->tfm;
}

/**
 * tipc_aead_init - Initiate TIPC AEAD
 * @aead: returned new TIPC AEAD key handle pointer
 * @ukey: pointer to user key data
 * @mode: the key mode
 *
 * Allocate a (list of) new cipher transformation (TFM) with the specific user
 * key data if valid. The number of the allocated TFMs can be set via the sysfs
 * "net/tipc/max_tfms" first.
 * Also, all the other AEAD data are also initialized.
 *
 * Return: 0 if the initiation is successful, otherwise: < 0
 */
static int tipc_aead_init(struct tipc_aead **aead, struct tipc_aead_key *ukey,
                          u8 mode)
{
        struct tipc_tfm *tfm_entry, *head;
        struct crypto_aead *tfm;
        struct tipc_aead *tmp;
        int keylen, err, cpu;
        int tfm_cnt = 0;

        if (unlikely(*aead))
                return -EEXIST;

        /* Allocate a new AEAD */
        tmp = kzalloc(sizeof(*tmp), GFP_ATOMIC);
        if (unlikely(!tmp))
                return -ENOMEM;

        /* The key consists of two parts: [AES-KEY][SALT] */
        keylen = ukey->keylen - TIPC_AES_GCM_SALT_SIZE;

        /* Allocate per-cpu TFM entry pointer */
        tmp->tfm_entry = alloc_percpu(struct tipc_tfm *);
        if (!tmp->tfm_entry) {
                kzfree(tmp);
                return -ENOMEM;
        }

        /* Make a list of TFMs with the user key data */
        do {
                tfm = crypto_alloc_aead(ukey->alg_name, 0, 0);
                if (IS_ERR(tfm)) {
                        err = PTR_ERR(tfm);
                        break;
                }

                if (unlikely(!tfm_cnt &&
                             crypto_aead_ivsize(tfm) != TIPC_AES_GCM_IV_SIZE)) {
                        crypto_free_aead(tfm);
                        err = -ENOTSUPP;
                        break;
                }

                err = crypto_aead_setauthsize(tfm, TIPC_AES_GCM_TAG_SIZE);
                err |= crypto_aead_setkey(tfm, ukey->key, keylen);
                if (unlikely(err)) {
                        crypto_free_aead(tfm);
                        break;
                }

                tfm_entry = kmalloc(sizeof(*tfm_entry), GFP_KERNEL);
                if (unlikely(!tfm_entry)) {
                        crypto_free_aead(tfm);
                        err = -ENOMEM;
                        break;
                }
                INIT_LIST_HEAD(&tfm_entry->list);
                tfm_entry->tfm = tfm;

                /* First entry? */
                if (!tfm_cnt) {
                        head = tfm_entry;
                        for_each_possible_cpu(cpu) {
                                *per_cpu_ptr(tmp->tfm_entry, cpu) = head;
                        }
                } else {
                        list_add_tail(&tfm_entry->list, &head->list);
                }

        } while (++tfm_cnt < sysctl_tipc_max_tfms);

        /* Not any TFM is allocated? */
        if (!tfm_cnt) {
                free_percpu(tmp->tfm_entry);
                kzfree(tmp);
                return err;
        }

        /* Copy some chars from the user key as a hint */
        memcpy(tmp->hint, ukey->key, TIPC_AEAD_HINT_LEN);
        tmp->hint[TIPC_AEAD_HINT_LEN] = '\0';

        /* Initialize the other data */
        tmp->mode = mode;
        tmp->cloned = NULL;
        tmp->authsize = TIPC_AES_GCM_TAG_SIZE;
        memcpy(&tmp->salt, ukey->key + keylen, TIPC_AES_GCM_SALT_SIZE);
        atomic_set(&tmp->users, 0);
        atomic64_set(&tmp->seqno, 0);
        refcount_set(&tmp->refcnt, 1);

        *aead = tmp;
        return 0;
}

/**
 * tipc_aead_clone - Clone a TIPC AEAD key
 * @dst: dest key for the cloning
 * @src: source key to clone from
 *
 * Make a "copy" of the source AEAD key data to the dest, the TFMs list is
 * common for the keys.
 * A reference to the source is hold in the "cloned" pointer for the later
 * freeing purposes.
 *
 * Note: this must be done in cluster-key mode only!
 * Return: 0 in case of success, otherwise < 0
 */
static int tipc_aead_clone(struct tipc_aead **dst, struct tipc_aead *src)
{
        struct tipc_aead *aead;
        int cpu;

        if (!src)
                return -ENOKEY;

        if (src->mode != CLUSTER_KEY)
                return -EINVAL;

        if (unlikely(*dst))
                return -EEXIST;

        aead = kzalloc(sizeof(*aead), GFP_ATOMIC);
        if (unlikely(!aead))
                return -ENOMEM;

        aead->tfm_entry = alloc_percpu_gfp(struct tipc_tfm *, GFP_ATOMIC);
        if (unlikely(!aead->tfm_entry)) {
                kzfree(aead);
                return -ENOMEM;
        }

        for_each_possible_cpu(cpu) {
                *per_cpu_ptr(aead->tfm_entry, cpu) =
                                *per_cpu_ptr(src->tfm_entry, cpu);
        }

        memcpy(aead->hint, src->hint, sizeof(src->hint));
        aead->mode = src->mode;
        aead->salt = src->salt;
        aead->authsize = src->authsize;
        atomic_set(&aead->users, 0);
        atomic64_set(&aead->seqno, 0);
        refcount_set(&aead->refcnt, 1);

        WARN_ON(!refcount_inc_not_zero(&src->refcnt));
        aead->cloned = src;

        *dst = aead;
        return 0;
}

/**
 * tipc_aead_mem_alloc - Allocate memory for AEAD request operations
 * @tfm: cipher handle to be registered with the request
 * @crypto_ctx_size: size of crypto context for callback
 * @iv: returned pointer to IV data
 * @req: returned pointer to AEAD request data
 * @sg: returned pointer to SG lists
 * @nsg: number of SG lists to be allocated
 *
 * Allocate memory to store the crypto context data, AEAD request, IV and SG
 * lists, the memory layout is as follows:
 * crypto_ctx || iv || aead_req || sg[]
 *
 * Return: the pointer to the memory areas in case of success, otherwise NULL
 */
static void *tipc_aead_mem_alloc(struct crypto_aead *tfm,
                                 unsigned int crypto_ctx_size,
                                 u8 **iv, struct aead_request **req,
                                 struct scatterlist **sg, int nsg)
{
        unsigned int iv_size, req_size;
        unsigned int len;
        u8 *mem;

        iv_size = crypto_aead_ivsize(tfm);
        req_size = sizeof(**req) + crypto_aead_reqsize(tfm);

        len = crypto_ctx_size;
        len += iv_size;
        len += crypto_aead_alignmask(tfm) & ~(crypto_tfm_ctx_alignment() - 1);
        len = ALIGN(len, crypto_tfm_ctx_alignment());
        len += req_size;
        len = ALIGN(len, __alignof__(struct scatterlist));
        len += nsg * sizeof(**sg);

        mem = kmalloc(len, GFP_ATOMIC);
        if (!mem)
                return NULL;

        *iv = (u8 *)PTR_ALIGN(mem + crypto_ctx_size,
                              crypto_aead_alignmask(tfm) + 1);
        *req = (struct aead_request *)PTR_ALIGN(*iv + iv_size,
                                                crypto_tfm_ctx_alignment());
        *sg = (struct scatterlist *)PTR_ALIGN((u8 *)*req + req_size,
                                              __alignof__(struct scatterlist));

        return (void *)mem;
}

/**
 * tipc_aead_encrypt - Encrypt a message
 * @aead: TIPC AEAD key for the message encryption
 * @skb: the input/output skb
 * @b: TIPC bearer where the message will be delivered after the encryption
 * @dst: the destination media address
 * @__dnode: TIPC dest node if "known"
 *
 * Return:
 * 0                   : if the encryption has completed
 * -EINPROGRESS/-EBUSY : if a callback will be performed
 * < 0                 : the encryption has failed
 */
static int tipc_aead_encrypt(struct tipc_aead *aead, struct sk_buff *skb,
                             struct tipc_bearer *b,
                             struct tipc_media_addr *dst,
                             struct tipc_node *__dnode)
{
        struct crypto_aead *tfm = tipc_aead_tfm_next(aead);
        struct tipc_crypto_tx_ctx *tx_ctx;
        struct aead_request *req;
        struct sk_buff *trailer;
        struct scatterlist *sg;
        struct tipc_ehdr *ehdr;
        int ehsz, len, tailen, nsg, rc;
        void *ctx;
        u32 salt;
        u8 *iv;

        /* Make sure message len at least 4-byte aligned */
        len = ALIGN(skb->len, 4);
        tailen = len - skb->len + aead->authsize;

        /* Expand skb tail for authentication tag:
         * As for simplicity, we'd have made sure skb having enough tailroom
         * for authentication tag @skb allocation. Even when skb is nonlinear
         * but there is no frag_list, it should be still fine!
         * Otherwise, we must cow it to be a writable buffer with the tailroom.
         */
#ifdef TIPC_CRYPTO_DEBUG
        SKB_LINEAR_ASSERT(skb);
        if (tailen > skb_tailroom(skb)) {
                pr_warn("TX: skb tailroom is not enough: %d, requires: %d\n",
                        skb_tailroom(skb), tailen);
        }
#endif

        if (unlikely(!skb_cloned(skb) && tailen <= skb_tailroom(skb))) {
                nsg = 1;
                trailer = skb;
        } else {
                /* TODO: We could avoid skb_cow_data() if skb has no frag_list
                 * e.g. by skb_fill_page_desc() to add another page to the skb
                 * with the wanted tailen... However, page skbs look not often,
                 * so take it easy now!
                 * Cloned skbs e.g. from link_xmit() seems no choice though :(
                 */
                nsg = skb_cow_data(skb, tailen, &trailer);
                if (unlikely(nsg < 0)) {
                        pr_err("TX: skb_cow_data() returned %d\n", nsg);
                        return nsg;
                }
        }

        pskb_put(skb, trailer, tailen);

        /* Allocate memory for the AEAD operation */
        ctx = tipc_aead_mem_alloc(tfm, sizeof(*tx_ctx), &iv, &req, &sg, nsg);
        if (unlikely(!ctx))
                return -ENOMEM;
        TIPC_SKB_CB(skb)->crypto_ctx = ctx;

        /* Map skb to the sg lists */
        sg_init_table(sg, nsg);
        rc = skb_to_sgvec(skb, sg, 0, skb->len);
        if (unlikely(rc < 0)) {
                pr_err("TX: skb_to_sgvec() returned %d, nsg %d!\n", rc, nsg);
                goto exit;
        }

        /* Prepare IV: [SALT (4 octets)][SEQNO (8 octets)]
         * In case we're in cluster-key mode, SALT is varied by xor-ing with
         * the source address (or w0 of id), otherwise with the dest address
         * if dest is known.
         */
        ehdr = (struct tipc_ehdr *)skb->data;
        salt = aead->salt;
        if (aead->mode == CLUSTER_KEY)
                salt ^= ehdr->addr; /* __be32 */
        else if (__dnode)
                salt ^= tipc_node_get_addr(__dnode);
        memcpy(iv, &salt, 4);
        memcpy(iv + 4, (u8 *)&ehdr->seqno, 8);

        /* Prepare request */
        ehsz = tipc_ehdr_size(ehdr);
        aead_request_set_tfm(req, tfm);
        aead_request_set_ad(req, ehsz);
        aead_request_set_crypt(req, sg, sg, len - ehsz, iv);

        /* Set callback function & data */
        aead_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
                                  tipc_aead_encrypt_done, skb);
        tx_ctx = (struct tipc_crypto_tx_ctx *)ctx;
        tx_ctx->aead = aead;
        tx_ctx->bearer = b;
        memcpy(&tx_ctx->dst, dst, sizeof(*dst));

        /* Hold bearer */
        if (unlikely(!tipc_bearer_hold(b))) {
                rc = -ENODEV;
                goto exit;
        }

        /* Now, do encrypt */
        rc = crypto_aead_encrypt(req);
        if (rc == -EINPROGRESS || rc == -EBUSY)
                return rc;

        tipc_bearer_put(b);

exit:
        kfree(ctx);
        TIPC_SKB_CB(skb)->crypto_ctx = NULL;
        return rc;
}

static void tipc_aead_encrypt_done(struct crypto_async_request *base, int err)
{
        struct sk_buff *skb = base->data;
        struct tipc_crypto_tx_ctx *tx_ctx = TIPC_SKB_CB(skb)->crypto_ctx;
        struct tipc_bearer *b = tx_ctx->bearer;
        struct tipc_aead *aead = tx_ctx->aead;
        struct tipc_crypto *tx = aead->crypto;
        struct net *net = tx->net;

        switch (err) {
        case 0:
                this_cpu_inc(tx->stats->stat[STAT_ASYNC_OK]);
                if (likely(test_bit(0, &b->up)))
                        b->media->send_msg(net, skb, b, &tx_ctx->dst);
                else
                        kfree_skb(skb);
                break;
        case -EINPROGRESS:
                return;
        default:
                this_cpu_inc(tx->stats->stat[STAT_ASYNC_NOK]);
                kfree_skb(skb);
                break;
        }

        kfree(tx_ctx);
        tipc_bearer_put(b);
        tipc_aead_put(aead);
}

/**
 * tipc_aead_decrypt - Decrypt an encrypted message
 * @net: struct net
 * @aead: TIPC AEAD for the message decryption
 * @skb: the input/output skb
 * @b: TIPC bearer where the message has been received
 *
 * Return:
 * 0                   : if the decryption has completed
 * -EINPROGRESS/-EBUSY : if a callback will be performed
 * < 0                 : the decryption has failed
 */
static int tipc_aead_decrypt(struct net *net, struct tipc_aead *aead,
                             struct sk_buff *skb, struct tipc_bearer *b)
{
        struct tipc_crypto_rx_ctx *rx_ctx;
        struct aead_request *req;
        struct crypto_aead *tfm;
        struct sk_buff *unused;
        struct scatterlist *sg;
        struct tipc_ehdr *ehdr;
        int ehsz, nsg, rc;
        void *ctx;
        u32 salt;
        u8 *iv;

        if (unlikely(!aead))
                return -ENOKEY;

        /* Cow skb data if needed */
        if (likely(!skb_cloned(skb) &&
                   (!skb_is_nonlinear(skb) || !skb_has_frag_list(skb)))) {
                nsg = 1 + skb_shinfo(skb)->nr_frags;
        } else {
                nsg = skb_cow_data(skb, 0, &unused);
                if (unlikely(nsg < 0)) {
                        pr_err("RX: skb_cow_data() returned %d\n", nsg);
                        return nsg;
                }
        }

        /* Allocate memory for the AEAD operation */
        tfm = tipc_aead_tfm_next(aead);
        ctx = tipc_aead_mem_alloc(tfm, sizeof(*rx_ctx), &iv, &req, &sg, nsg);
        if (unlikely(!ctx))
                return -ENOMEM;
        TIPC_SKB_CB(skb)->crypto_ctx = ctx;

        /* Map skb to the sg lists */
        sg_init_table(sg, nsg);
        rc = skb_to_sgvec(skb, sg, 0, skb->len);
        if (unlikely(rc < 0)) {
                pr_err("RX: skb_to_sgvec() returned %d, nsg %d\n", rc, nsg);
                goto exit;
        }

        /* Reconstruct IV: */
        ehdr = (struct tipc_ehdr *)skb->data;
        salt = aead->salt;
        if (aead->mode == CLUSTER_KEY)
                salt ^= ehdr->addr; /* __be32 */
        else if (ehdr->destined)
                salt ^= tipc_own_addr(net);
        memcpy(iv, &salt, 4);
        memcpy(iv + 4, (u8 *)&ehdr->seqno, 8);

        /* Prepare request */
        ehsz = tipc_ehdr_size(ehdr);
        aead_request_set_tfm(req, tfm);
        aead_request_set_ad(req, ehsz);
        aead_request_set_crypt(req, sg, sg, skb->len - ehsz, iv);

        /* Set callback function & data */
        aead_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
                                  tipc_aead_decrypt_done, skb);
        rx_ctx = (struct tipc_crypto_rx_ctx *)ctx;
        rx_ctx->aead = aead;
        rx_ctx->bearer = b;

        /* Hold bearer */
        if (unlikely(!tipc_bearer_hold(b))) {
                rc = -ENODEV;
                goto exit;
        }

        /* Now, do decrypt */
        rc = crypto_aead_decrypt(req);
        if (rc == -EINPROGRESS || rc == -EBUSY)
                return rc;

        tipc_bearer_put(b);

exit:
        kfree(ctx);
        TIPC_SKB_CB(skb)->crypto_ctx = NULL;
        return rc;
}

static void tipc_aead_decrypt_done(struct crypto_async_request *base, int err)
{
        struct sk_buff *skb = base->data;
        struct tipc_crypto_rx_ctx *rx_ctx = TIPC_SKB_CB(skb)->crypto_ctx;
        struct tipc_bearer *b = rx_ctx->bearer;
        struct tipc_aead *aead = rx_ctx->aead;
        struct tipc_crypto_stats __percpu *stats = aead->crypto->stats;
        struct net *net = aead->crypto->net;

        switch (err) {
        case 0:
                this_cpu_inc(stats->stat[STAT_ASYNC_OK]);
                break;
        case -EINPROGRESS:
                return;
        default:
                this_cpu_inc(stats->stat[STAT_ASYNC_NOK]);
                break;
        }

        kfree(rx_ctx);
        tipc_crypto_rcv_complete(net, aead, b, &skb, err);
        if (likely(skb)) {
                if (likely(test_bit(0, &b->up)))
                        tipc_rcv(net, skb, b);
                else
                        kfree_skb(skb);
        }

        tipc_bearer_put(b);
}

static inline int tipc_ehdr_size(struct tipc_ehdr *ehdr)
{
        return (ehdr->user != LINK_CONFIG) ? EHDR_SIZE : EHDR_CFG_SIZE;
}

/**
 * tipc_ehdr_validate - Validate an encryption message
 * @skb: the message buffer
 *
 * Returns "true" if this is a valid encryption message, otherwise "false"
 */
bool tipc_ehdr_validate(struct sk_buff *skb)
{
        struct tipc_ehdr *ehdr;
        int ehsz;

        if (unlikely(!pskb_may_pull(skb, EHDR_MIN_SIZE)))
                return false;

        ehdr = (struct tipc_ehdr *)skb->data;
        if (unlikely(ehdr->version != TIPC_EVERSION))
                return false;
        ehsz = tipc_ehdr_size(ehdr);
        if (unlikely(!pskb_may_pull(skb, ehsz)))
                return false;
        if (unlikely(skb->len <= ehsz + TIPC_AES_GCM_TAG_SIZE))
                return false;
        if (unlikely(!ehdr->tx_key))
                return false;

        return true;
}

/**
 * tipc_ehdr_build - Build TIPC encryption message header
 * @net: struct net
 * @aead: TX AEAD key to be used for the message encryption
 * @tx_key: key id used for the message encryption
 * @skb: input/output message skb
 * @__rx: RX crypto handle if dest is "known"
 *
 * Return: the header size if the building is successful, otherwise < 0
 */
static int tipc_ehdr_build(struct net *net, struct tipc_aead *aead,
                           u8 tx_key, struct sk_buff *skb,
                           struct tipc_crypto *__rx)
{
        struct tipc_msg *hdr = buf_msg(skb);
        struct tipc_ehdr *ehdr;
        u32 user = msg_user(hdr);
        u64 seqno;
        int ehsz;

        /* Make room for encryption header */
        ehsz = (user != LINK_CONFIG) ? EHDR_SIZE : EHDR_CFG_SIZE;
        WARN_ON(skb_headroom(skb) < ehsz);
        ehdr = (struct tipc_ehdr *)skb_push(skb, ehsz);

        /* Obtain a seqno first:
         * Use the key seqno (= cluster wise) if dest is unknown or we're in
         * cluster key mode, otherwise it's better for a per-peer seqno!
         */
        if (!__rx || aead->mode == CLUSTER_KEY)
                seqno = atomic64_inc_return(&aead->seqno);
        else
                seqno = atomic64_inc_return(&__rx->sndnxt);

        /* Revoke the key if seqno is wrapped around */
        if (unlikely(!seqno))
                return tipc_crypto_key_revoke(net, tx_key);

        /* Word 1-2 */
        ehdr->seqno = cpu_to_be64(seqno);

        /* Words 0, 3- */
        ehdr->version = TIPC_EVERSION;
        ehdr->user = 0;
        ehdr->keepalive = 0;
        ehdr->tx_key = tx_key;
        ehdr->destined = (__rx) ? 1 : 0;
        ehdr->rx_key_active = (__rx) ? __rx->key.active : 0;
        ehdr->reserved_1 = 0;
        ehdr->reserved_2 = 0;

        switch (user) {
        case LINK_CONFIG:
                ehdr->user = LINK_CONFIG;
                memcpy(ehdr->id, tipc_own_id(net), NODE_ID_LEN);
                break;
        default:
                if (user == LINK_PROTOCOL && msg_type(hdr) == STATE_MSG) {
                        ehdr->user = LINK_PROTOCOL;
                        ehdr->keepalive = msg_is_keepalive(hdr);
                }
                ehdr->addr = hdr->hdr[3];
                break;
        }

        return ehsz;
}

static inline void tipc_crypto_key_set_state(struct tipc_crypto *c,
                                             u8 new_passive,
                                             u8 new_active,
                                             u8 new_pending)
{
#ifdef TIPC_CRYPTO_DEBUG
        struct tipc_key old = c->key;
        char buf[32];
#endif

        c->key.keys = ((new_passive & KEY_MASK) << (KEY_BITS * 2)) |
                      ((new_active  & KEY_MASK) << (KEY_BITS)) |
                      ((new_pending & KEY_MASK));

#ifdef TIPC_CRYPTO_DEBUG
        pr_info("%s(%s): key changing %s ::%pS\n",
                (c->node) ? "RX" : "TX",
                (c->node) ? tipc_node_get_id_str(c->node) :
                            tipc_own_id_string(c->net),
                tipc_key_change_dump(old, c->key, buf),
                __builtin_return_address(0));
#endif
}

/**
 * tipc_crypto_key_init - Initiate a new user / AEAD key
 * @c: TIPC crypto to which new key is attached
 * @ukey: the user key
 * @mode: the key mode (CLUSTER_KEY or PER_NODE_KEY)
 *
 * A new TIPC AEAD key will be allocated and initiated with the specified user
 * key, then attached to the TIPC crypto.
 *
 * Return: new key id in case of success, otherwise: < 0
 */
int tipc_crypto_key_init(struct tipc_crypto *c, struct tipc_aead_key *ukey,
                         u8 mode)
{
        struct tipc_aead *aead = NULL;
        int rc = 0;

        /* Initiate with the new user key */
        rc = tipc_aead_init(&aead, ukey, mode);

        /* Attach it to the crypto */
        if (likely(!rc)) {
                rc = tipc_crypto_key_attach(c, aead, 0);
                if (rc < 0)
                        tipc_aead_free(&aead->rcu);
        }

        pr_info("%s(%s): key initiating, rc %d!\n",
                (c->node) ? "RX" : "TX",
                (c->node) ? tipc_node_get_id_str(c->node) :
                            tipc_own_id_string(c->net),
                rc);

        return rc;
}

/**
 * tipc_crypto_key_attach - Attach a new AEAD key to TIPC crypto
 * @c: TIPC crypto to which the new AEAD key is attached
 * @aead: the new AEAD key pointer
 * @pos: desired slot in the crypto key array, = 0 if any!
 *
 * Return: new key id in case of success, otherwise: -EBUSY
 */
static int tipc_crypto_key_attach(struct tipc_crypto *c,
                                  struct tipc_aead *aead, u8 pos)
{
        u8 new_pending, new_passive, new_key;
        struct tipc_key key;
        int rc = -EBUSY;

        spin_lock_bh(&c->lock);
        key = c->key;
        if (key.active && key.passive)
                goto exit;
        if (key.passive && !tipc_aead_users(c->aead[key.passive]))
                goto exit;
        if (key.pending) {
                if (pos)
                        goto exit;
                if (tipc_aead_users(c->aead[key.pending]) > 0)
                        goto exit;
                /* Replace it */
                new_pending = key.pending;
                new_passive = key.passive;
                new_key = new_pending;
        } else {
                if (pos) {
                        if (key.active && pos != key_next(key.active)) {
                                new_pending = key.pending;
                                new_passive = pos;
                                new_key = new_passive;
                                goto attach;
                        } else if (!key.active && !key.passive) {
                                new_pending = pos;
                                new_passive = key.passive;
                                new_key = new_pending;
                                goto attach;
                        }
                }
                new_pending = key_next(key.active ?: key.passive);
                new_passive = key.passive;
                new_key = new_pending;
        }

attach:
        aead->crypto = c;
        tipc_crypto_key_set_state(c, new_passive, key.active, new_pending);
        tipc_aead_rcu_replace(c->aead[new_key], aead, &c->lock);

        c->working = 1;
        c->timer1 = jiffies;
        c->timer2 = jiffies;
        rc = new_key;

exit:
        spin_unlock_bh(&c->lock);
        return rc;
}

void tipc_crypto_key_flush(struct tipc_crypto *c)
{
        int k;

        spin_lock_bh(&c->lock);
        c->working = 0;
        tipc_crypto_key_set_state(c, 0, 0, 0);
        for (k = KEY_MIN; k <= KEY_MAX; k++)
                tipc_crypto_key_detach(c->aead[k], &c->lock);
        atomic_set(&c->peer_rx_active, 0);
        atomic64_set(&c->sndnxt, 0);
        spin_unlock_bh(&c->lock);
}

/**
 * tipc_crypto_key_try_align - Align RX keys if possible
 * @rx: RX crypto handle
 * @new_pending: new pending slot if aligned (= TX key from peer)
 *
 * Peer has used an unknown key slot, this only happens when peer has left and
 * rejoned, or we are newcomer.
 * That means, there must be no active key but a pending key at unaligned slot.
 * If so, we try to move the pending key to the new slot.
 * Note: A potential passive key can exist, it will be shifted correspondingly!
 *
 * Return: "true" if key is successfully aligned, otherwise "false"
 */
static bool tipc_crypto_key_try_align(struct tipc_crypto *rx, u8 new_pending)
{
        struct tipc_aead *tmp1, *tmp2 = NULL;
        struct tipc_key key;
        bool aligned = false;
        u8 new_passive = 0;
        int x;

        spin_lock(&rx->lock);
        key = rx->key;
        if (key.pending == new_pending) {
                aligned = true;
                goto exit;
        }
        if (key.active)
                goto exit;
        if (!key.pending)
                goto exit;
        if (tipc_aead_users(rx->aead[key.pending]) > 0)
                goto exit;

        /* Try to "isolate" this pending key first */
        tmp1 = tipc_aead_rcu_ptr(rx->aead[key.pending], &rx->lock);
        if (!refcount_dec_if_one(&tmp1->refcnt))
                goto exit;
        rcu_assign_pointer(rx->aead[key.pending], NULL);

        /* Move passive key if any */
        if (key.passive) {
                tmp2 = rcu_replace_pointer(rx->aead[key.passive], tmp2, lockdep_is_held(&rx->lock));
                x = (key.passive - key.pending + new_pending) % KEY_MAX;
                new_passive = (x <= 0) ? x + KEY_MAX : x;
        }

        /* Re-allocate the key(s) */
        tipc_crypto_key_set_state(rx, new_passive, 0, new_pending);
        rcu_assign_pointer(rx->aead[new_pending], tmp1);
        if (new_passive)
                rcu_assign_pointer(rx->aead[new_passive], tmp2);
        refcount_set(&tmp1->refcnt, 1);
        aligned = true;
        pr_info("RX(%s): key is aligned!\n", tipc_node_get_id_str(rx->node));

exit:
        spin_unlock(&rx->lock);
        return aligned;
}

/**
 * tipc_crypto_key_pick_tx - Pick one TX key for message decryption
 * @tx: TX crypto handle
 * @rx: RX crypto handle (can be NULL)
 * @skb: the message skb which will be decrypted later
 *
 * This function looks up the existing TX keys and pick one which is suitable
 * for the message decryption, that must be a cluster key and not used before
 * on the same message (i.e. recursive).
 *
 * Return: the TX AEAD key handle in case of success, otherwise NULL
 */
static struct tipc_aead *tipc_crypto_key_pick_tx(struct tipc_crypto *tx,
                                                 struct tipc_crypto *rx,
                                                 struct sk_buff *skb)
{
        struct tipc_skb_cb *skb_cb = TIPC_SKB_CB(skb);
        struct tipc_aead *aead = NULL;
        struct tipc_key key = tx->key;
        u8 k, i = 0;

        /* Initialize data if not yet */
        if (!skb_cb->tx_clone_deferred) {
                skb_cb->tx_clone_deferred = 1;
                memset(&skb_cb->tx_clone_ctx, 0, sizeof(skb_cb->tx_clone_ctx));
        }

        skb_cb->tx_clone_ctx.rx = rx;
        if (++skb_cb->tx_clone_ctx.recurs > 2)
                return NULL;

        /* Pick one TX key */
        spin_lock(&tx->lock);
        do {
                k = (i == 0) ? key.pending :
                        ((i == 1) ? key.active : key.passive);
                if (!k)
                        continue;
                aead = tipc_aead_rcu_ptr(tx->aead[k], &tx->lock);
                if (!aead)
                        continue;
                if (aead->mode != CLUSTER_KEY ||
                    aead == skb_cb->tx_clone_ctx.last) {
                        aead = NULL;
                        continue;
                }
                /* Ok, found one cluster key */
                skb_cb->tx_clone_ctx.last = aead;
                WARN_ON(skb->next);
                skb->next = skb_clone(skb, GFP_ATOMIC);
                if (unlikely(!skb->next))
                        pr_warn("Failed to clone skb for next round if any\n");
                WARN_ON(!refcount_inc_not_zero(&aead->refcnt));
                break;
        } while (++i < 3);
        spin_unlock(&tx->lock);

        return aead;
}

/**
 * tipc_crypto_key_synch: Synch own key data according to peer key status
 * @rx: RX crypto handle
 * @new_rx_active: latest RX active key from peer
 * @hdr: TIPCv2 message
 *
 * This function updates the peer node related data as the peer RX active key
 * has changed, so the number of TX keys' users on this node are increased and
 * decreased correspondingly.
 *
 * The "per-peer" sndnxt is also reset when the peer key has switched.
 */
static void tipc_crypto_key_synch(struct tipc_crypto *rx, u8 new_rx_active,
                                  struct tipc_msg *hdr)
{
        struct net *net = rx->net;
        struct tipc_crypto *tx = tipc_net(net)->crypto_tx;
        u8 cur_rx_active;

        /* TX might be even not ready yet */
        if (unlikely(!tx->key.active && !tx->key.pending))
                return;

        cur_rx_active = atomic_read(&rx->peer_rx_active);
        if (likely(cur_rx_active == new_rx_active))
                return;

        /* Make sure this message destined for this node */
        if (unlikely(msg_short(hdr) ||
                     msg_destnode(hdr) != tipc_own_addr(net)))
                return;

        /* Peer RX active key has changed, try to update owns' & TX users */
        if (atomic_cmpxchg(&rx->peer_rx_active,
                           cur_rx_active,
                           new_rx_active) == cur_rx_active) {
                if (new_rx_active)
                        tipc_aead_users_inc(tx->aead[new_rx_active], INT_MAX);
                if (cur_rx_active)
                        tipc_aead_users_dec(tx->aead[cur_rx_active], 0);

                atomic64_set(&rx->sndnxt, 0);
                /* Mark the point TX key users changed */
                tx->timer1 = jiffies;

#ifdef TIPC_CRYPTO_DEBUG
                pr_info("TX(%s): key users changed %d-- %d++, peer RX(%s)\n",
                        tipc_own_id_string(net), cur_rx_active,
                        new_rx_active, tipc_node_get_id_str(rx->node));
#endif
        }
}

static int tipc_crypto_key_revoke(struct net *net, u8 tx_key)
{
        struct tipc_crypto *tx = tipc_net(net)->crypto_tx;
        struct tipc_key key;

        spin_lock(&tx->lock);
        key = tx->key;
        WARN_ON(!key.active || tx_key != key.active);

        /* Free the active key */
        tipc_crypto_key_set_state(tx, key.passive, 0, key.pending);
        tipc_crypto_key_detach(tx->aead[key.active], &tx->lock);
        spin_unlock(&tx->lock);

        pr_warn("TX(%s): key is revoked!\n", tipc_own_id_string(net));
        return -EKEYREVOKED;
}

int tipc_crypto_start(struct tipc_crypto **crypto, struct net *net,
                      struct tipc_node *node)
{
        struct tipc_crypto *c;

        if (*crypto)
                return -EEXIST;

        /* Allocate crypto */
        c = kzalloc(sizeof(*c), GFP_ATOMIC);
        if (!c)
                return -ENOMEM;

        /* Allocate statistic structure */
        c->stats = alloc_percpu_gfp(struct tipc_crypto_stats, GFP_ATOMIC);
        if (!c->stats) {
                kzfree(c);
                return -ENOMEM;
        }

        c->working = 0;
        c->net = net;
        c->node = node;
        tipc_crypto_key_set_state(c, 0, 0, 0);
        atomic_set(&c->peer_rx_active, 0);
        atomic64_set(&c->sndnxt, 0);
        c->timer1 = jiffies;
        c->timer2 = jiffies;
        spin_lock_init(&c->lock);
        *crypto = c;

        return 0;
}

void tipc_crypto_stop(struct tipc_crypto **crypto)
{
        struct tipc_crypto *c, *tx, *rx;
        bool is_rx;
        u8 k;

        if (!*crypto)
                return;

        rcu_read_lock();
        /* RX stopping? => decrease TX key users if any */
        is_rx = !!((*crypto)->node);
        if (is_rx) {
                rx = *crypto;
                tx = tipc_net(rx->net)->crypto_tx;
                k = atomic_read(&rx->peer_rx_active);
                if (k) {
                        tipc_aead_users_dec(tx->aead[k], 0);
                        /* Mark the point TX key users changed */
                        tx->timer1 = jiffies;
                }
        }

        /* Release AEAD keys */
        c = *crypto;
        for (k = KEY_MIN; k <= KEY_MAX; k++)
                tipc_aead_put(rcu_dereference(c->aead[k]));
        rcu_read_unlock();

        pr_warn("%s(%s) has been purged, node left!\n",
                (is_rx) ? "RX" : "TX",
                (is_rx) ? tipc_node_get_id_str((*crypto)->node) :
                          tipc_own_id_string((*crypto)->net));

        /* Free this crypto statistics */
        free_percpu(c->stats);

        *crypto = NULL;
        kzfree(c);
}

void tipc_crypto_timeout(struct tipc_crypto *rx)
{
        struct tipc_net *tn = tipc_net(rx->net);
        struct tipc_crypto *tx = tn->crypto_tx;
        struct tipc_key key;
        u8 new_pending, new_passive;
        int cmd;

        /* TX key activating:
         * The pending key (users > 0) -> active
         * The active key if any (users == 0) -> free
         */
        spin_lock(&tx->lock);
        key = tx->key;
        if (key.active && tipc_aead_users(tx->aead[key.active]) > 0)
                goto s1;
        if (!key.pending || tipc_aead_users(tx->aead[key.pending]) <= 0)
                goto s1;
        if (time_before(jiffies, tx->timer1 + TIPC_TX_LASTING_LIM))
                goto s1;

        tipc_crypto_key_set_state(tx, key.passive, key.pending, 0);
        if (key.active)
                tipc_crypto_key_detach(tx->aead[key.active], &tx->lock);
        this_cpu_inc(tx->stats->stat[STAT_SWITCHES]);
        pr_info("TX(%s): key %d is activated!\n", tipc_own_id_string(tx->net),
                key.pending);

s1:
        spin_unlock(&tx->lock);

        /* RX key activating:
         * The pending key (users > 0) -> active
         * The active key if any -> passive, freed later
         */
        spin_lock(&rx->lock);
        key = rx->key;
        if (!key.pending || tipc_aead_users(rx->aead[key.pending]) <= 0)
                goto s2;

        new_pending = (key.passive &&
                       !tipc_aead_users(rx->aead[key.passive])) ?
                                       key.passive : 0;
        new_passive = (key.active) ?: ((new_pending) ? 0 : key.passive);
        tipc_crypto_key_set_state(rx, new_passive, key.pending, new_pending);
        this_cpu_inc(rx->stats->stat[STAT_SWITCHES]);
        pr_info("RX(%s): key %d is activated!\n",
                tipc_node_get_id_str(rx->node), key.pending);
        goto s5;

s2:
        /* RX key "faulty" switching:
         * The faulty pending key (users < -30) -> passive
         * The passive key (users = 0) -> pending
         * Note: This only happens after RX deactivated - s3!
         */
        key = rx->key;
        if (!key.pending || tipc_aead_users(rx->aead[key.pending]) > -30)
                goto s3;
        if (!key.passive || tipc_aead_users(rx->aead[key.passive]) != 0)
                goto s3;

        new_pending = key.passive;
        new_passive = key.pending;
        tipc_crypto_key_set_state(rx, new_passive, key.active, new_pending);
        goto s5;

s3:
        /* RX key deactivating:
         * The passive key if any -> pending
         * The active key -> passive (users = 0) / pending
         * The pending key if any -> passive (users = 0)
         */
        key = rx->key;
        if (!key.active)
                goto s4;
        if (time_before(jiffies, rx->timer1 + TIPC_RX_ACTIVE_LIM))
                goto s4;

        new_pending = (key.passive) ?: key.active;
        new_passive = (key.passive) ? key.active : key.pending;
        tipc_aead_users_set(rx->aead[new_pending], 0);
        if (new_passive)
                tipc_aead_users_set(rx->aead[new_passive], 0);
        tipc_crypto_key_set_state(rx, new_passive, 0, new_pending);
        pr_info("RX(%s): key %d is deactivated!\n",
                tipc_node_get_id_str(rx->node), key.active);
        goto s5;

s4:
        /* RX key passive -> freed: */
        key = rx->key;
        if (!key.passive || !tipc_aead_users(rx->aead[key.passive]))
                goto s5;
        if (time_before(jiffies, rx->timer2 + TIPC_RX_PASSIVE_LIM))
                goto s5;

        tipc_crypto_key_set_state(rx, 0, key.active, key.pending);
        tipc_crypto_key_detach(rx->aead[key.passive], &rx->lock);
        pr_info("RX(%s): key %d is freed!\n", tipc_node_get_id_str(rx->node),
                key.passive);

s5:
        spin_unlock(&rx->lock);

        /* Limit max_tfms & do debug commands if needed */
        if (likely(sysctl_tipc_max_tfms <= TIPC_MAX_TFMS_LIM))
                return;

        cmd = sysctl_tipc_max_tfms;
        sysctl_tipc_max_tfms = TIPC_MAX_TFMS_DEF;
        tipc_crypto_do_cmd(rx->net, cmd);
}

/**
 * tipc_crypto_xmit - Build & encrypt TIPC message for xmit
 * @net: struct net
 * @skb: input/output message skb pointer
 * @b: bearer used for xmit later
 * @dst: destination media address
 * @__dnode: destination node for reference if any
 *
 * First, build an encryption message header on the top of the message, then
 * encrypt the original TIPC message by using the active or pending TX key.
 * If the encryption is successful, the encrypted skb is returned directly or
 * via the callback.
 * Otherwise, the skb is freed!
 *
 * Return:
 * 0                   : the encryption has succeeded (or no encryption)
 * -EINPROGRESS/-EBUSY : the encryption is ongoing, a callback will be made
 * -ENOKEK             : the encryption has failed due to no key
 * -EKEYREVOKED        : the encryption has failed due to key revoked
 * -ENOMEM             : the encryption has failed due to no memory
 * < 0                 : the encryption has failed due to other reasons
 */
int tipc_crypto_xmit(struct net *net, struct sk_buff **skb,
                     struct tipc_bearer *b, struct tipc_media_addr *dst,
                     struct tipc_node *__dnode)
{
        struct tipc_crypto *__rx = tipc_node_crypto_rx(__dnode);
        struct tipc_crypto *tx = tipc_net(net)->crypto_tx;
        struct tipc_crypto_stats __percpu *stats = tx->stats;
        struct tipc_key key = tx->key;
        struct tipc_aead *aead = NULL;
        struct sk_buff *probe;
        int rc = -ENOKEY;
        u8 tx_key;

        /* No encryption? */
        if (!tx->working)
                return 0;

        /* Try with the pending key if available and:
         * 1) This is the only choice (i.e. no active key) or;
         * 2) Peer has switched to this key (unicast only) or;
         * 3) It is time to do a pending key probe;
         */
        if (unlikely(key.pending)) {
                tx_key = key.pending;
                if (!key.active)
                        goto encrypt;
                if (__rx && atomic_read(&__rx->peer_rx_active) == tx_key)
                        goto encrypt;
                if (TIPC_SKB_CB(*skb)->probe)
                        goto encrypt;
                if (!__rx &&
                    time_after(jiffies, tx->timer2 + TIPC_TX_PROBE_LIM)) {
                        tx->timer2 = jiffies;
                        probe = skb_clone(*skb, GFP_ATOMIC);
                        if (probe) {
                                TIPC_SKB_CB(probe)->probe = 1;
                                tipc_crypto_xmit(net, &probe, b, dst, __dnode);
                                if (probe)
                                        b->media->send_msg(net, probe, b, dst);
                        }
                }
        }
        /* Else, use the active key if any */
        if (likely(key.active)) {
                tx_key = key.active;
                goto encrypt;
        }
        goto exit;

encrypt:
        aead = tipc_aead_get(tx->aead[tx_key]);
        if (unlikely(!aead))
                goto exit;
        rc = tipc_ehdr_build(net, aead, tx_key, *skb, __rx);
        if (likely(rc > 0))
                rc = tipc_aead_encrypt(aead, *skb, b, dst, __dnode);

exit:
        switch (rc) {
        case 0:
                this_cpu_inc(stats->stat[STAT_OK]);
                break;
        case -EINPROGRESS:
        case -EBUSY:
                this_cpu_inc(stats->stat[STAT_ASYNC]);
                *skb = NULL;
                return rc;
        default:
                this_cpu_inc(stats->stat[STAT_NOK]);
                if (rc == -ENOKEY)
                        this_cpu_inc(stats->stat[STAT_NOKEYS]);
                else if (rc == -EKEYREVOKED)
                        this_cpu_inc(stats->stat[STAT_BADKEYS]);
                kfree_skb(*skb);
                *skb = NULL;
                break;
        }

        tipc_aead_put(aead);
        return rc;
}

/**
 * tipc_crypto_rcv - Decrypt an encrypted TIPC message from peer
 * @net: struct net
 * @rx: RX crypto handle
 * @skb: input/output message skb pointer
 * @b: bearer where the message has been received
 *
 * If the decryption is successful, the decrypted skb is returned directly or
 * as the callback, the encryption header and auth tag will be trimed out
 * before forwarding to tipc_rcv() via the tipc_crypto_rcv_complete().
 * Otherwise, the skb will be freed!
 * Note: RX key(s) can be re-aligned, or in case of no key suitable, TX
 * cluster key(s) can be taken for decryption (- recursive).
 *
 * Return:
 * 0                   : the decryption has successfully completed
 * -EINPROGRESS/-EBUSY : the decryption is ongoing, a callback will be made
 * -ENOKEY             : the decryption has failed due to no key
 * -EBADMSG            : the decryption has failed due to bad message
 * -ENOMEM             : the decryption has failed due to no memory
 * < 0                 : the decryption has failed due to other reasons
 */
int tipc_crypto_rcv(struct net *net, struct tipc_crypto *rx,
                    struct sk_buff **skb, struct tipc_bearer *b)
{
        struct tipc_crypto *tx = tipc_net(net)->crypto_tx;
        struct tipc_crypto_stats __percpu *stats;
        struct tipc_aead *aead = NULL;
        struct tipc_key key;
        int rc = -ENOKEY;
        u8 tx_key = 0;

        /* New peer?
         * Let's try with TX key (i.e. cluster mode) & verify the skb first!
         */
        if (unlikely(!rx))
                goto pick_tx;

        /* Pick RX key according to TX key, three cases are possible:
         * 1) The current active key (likely) or;
         * 2) The pending (new or deactivated) key (if any) or;
         * 3) The passive or old active key (i.e. users > 0);
         */
        tx_key = ((struct tipc_ehdr *)(*skb)->data)->tx_key;
        key = rx->key;
        if (likely(tx_key == key.active))
                goto decrypt;
        if (tx_key == key.pending)
                goto decrypt;
        if (tx_key == key.passive) {
                rx->timer2 = jiffies;
                if (tipc_aead_users(rx->aead[key.passive]) > 0)
                        goto decrypt;
        }

        /* Unknown key, let's try to align RX key(s) */
        if (tipc_crypto_key_try_align(rx, tx_key))
                goto decrypt;

pick_tx:
        /* No key suitable? Try to pick one from TX... */
        aead = tipc_crypto_key_pick_tx(tx, rx, *skb);
        if (aead)
                goto decrypt;
        goto exit;

decrypt:
        rcu_read_lock();
        if (!aead)
                aead = tipc_aead_get(rx->aead[tx_key]);
        rc = tipc_aead_decrypt(net, aead, *skb, b);
        rcu_read_unlock();

exit:
        stats = ((rx) ?: tx)->stats;
        switch (rc) {
        case 0:
                this_cpu_inc(stats->stat[STAT_OK]);
                break;
        case -EINPROGRESS:
        case -EBUSY:
                this_cpu_inc(stats->stat[STAT_ASYNC]);
                *skb = NULL;
                tipc_aead_put(aead);
                return rc;
        default:
                this_cpu_inc(stats->stat[STAT_NOK]);
                if (rc == -ENOKEY) {
                        kfree_skb(*skb);
                        *skb = NULL;
                        if (rx)
                                tipc_node_put(rx->node);
                        this_cpu_inc(stats->stat[STAT_NOKEYS]);
                        return rc;
                } else if (rc == -EBADMSG) {
                        this_cpu_inc(stats->stat[STAT_BADMSGS]);
                }
                break;
        }

        tipc_crypto_rcv_complete(net, aead, b, skb, rc);
        return rc;
}

static void tipc_crypto_rcv_complete(struct net *net, struct tipc_aead *aead,
                                     struct tipc_bearer *b,
                                     struct sk_buff **skb, int err)
{
        struct tipc_skb_cb *skb_cb = TIPC_SKB_CB(*skb);
        struct tipc_crypto *rx = aead->crypto;
        struct tipc_aead *tmp = NULL;
        struct tipc_ehdr *ehdr;
        struct tipc_node *n;
        u8 rx_key_active;
        bool destined;

        /* Is this completed by TX? */
        if (unlikely(!rx->node)) {
                rx = skb_cb->tx_clone_ctx.rx;
#ifdef TIPC_CRYPTO_DEBUG
                pr_info("TX->RX(%s): err %d, aead %p, skb->next %p, flags %x\n",
                        (rx) ? tipc_node_get_id_str(rx->node) : "-", err, aead,
                        (*skb)->next, skb_cb->flags);
                pr_info("skb_cb [recurs %d, last %p], tx->aead [%p %p %p]\n",
                        skb_cb->tx_clone_ctx.recurs, skb_cb->tx_clone_ctx.last,
                        aead->crypto->aead[1], aead->crypto->aead[2],
                        aead->crypto->aead[3]);
#endif
                if (unlikely(err)) {
                        if (err == -EBADMSG && (*skb)->next)
                                tipc_rcv(net, (*skb)->next, b);
                        goto free_skb;
                }

                if (likely((*skb)->next)) {
                        kfree_skb((*skb)->next);
                        (*skb)->next = NULL;
                }
                ehdr = (struct tipc_ehdr *)(*skb)->data;
                if (!rx) {
                        WARN_ON(ehdr->user != LINK_CONFIG);
                        n = tipc_node_create(net, 0, ehdr->id, 0xffffu, 0,
                                             true);
                        rx = tipc_node_crypto_rx(n);
                        if (unlikely(!rx))
                                goto free_skb;
                }

                /* Skip cloning this time as we had a RX pending key */
                if (rx->key.pending)
                        goto rcv;
                if (tipc_aead_clone(&tmp, aead) < 0)
                        goto rcv;
                if (tipc_crypto_key_attach(rx, tmp, ehdr->tx_key) < 0) {
                        tipc_aead_free(&tmp->rcu);
                        goto rcv;
                }
                tipc_aead_put(aead);
                aead = tipc_aead_get(tmp);
        }

        if (unlikely(err)) {
                tipc_aead_users_dec(aead, INT_MIN);
                goto free_skb;
        }

        /* Set the RX key's user */
        tipc_aead_users_set(aead, 1);

rcv:
        /* Mark this point, RX works */
        rx->timer1 = jiffies;

        /* Remove ehdr & auth. tag prior to tipc_rcv() */
        ehdr = (struct tipc_ehdr *)(*skb)->data;
        destined = ehdr->destined;
        rx_key_active = ehdr->rx_key_active;
        skb_pull(*skb, tipc_ehdr_size(ehdr));
        pskb_trim(*skb, (*skb)->len - aead->authsize);

        /* Validate TIPCv2 message */
        if (unlikely(!tipc_msg_validate(skb))) {
                pr_err_ratelimited("Packet dropped after decryption!\n");
                goto free_skb;
        }

        /* Update peer RX active key & TX users */
        if (destined)
                tipc_crypto_key_synch(rx, rx_key_active, buf_msg(*skb));

        /* Mark skb decrypted */
        skb_cb->decrypted = 1;

        /* Clear clone cxt if any */
        if (likely(!skb_cb->tx_clone_deferred))
                goto exit;
        skb_cb->tx_clone_deferred = 0;
        memset(&skb_cb->tx_clone_ctx, 0, sizeof(skb_cb->tx_clone_ctx));
        goto exit;

free_skb:
        kfree_skb(*skb);
        *skb = NULL;

exit:
        tipc_aead_put(aead);
        if (rx)
                tipc_node_put(rx->node);
}

static void tipc_crypto_do_cmd(struct net *net, int cmd)
{
        struct tipc_net *tn = tipc_net(net);
        struct tipc_crypto *tx = tn->crypto_tx, *rx;
        struct list_head *p;
        unsigned int stat;
        int i, j, cpu;
        char buf[200];

        /* Currently only one command is supported */
        switch (cmd) {
        case 0xfff1:
                goto print_stats;
        default:
                return;
        }

print_stats:
        /* Print a header */
        pr_info("\n=============== TIPC Crypto Statistics ===============\n\n");

        /* Print key status */
        pr_info("Key status:\n");
        pr_info("TX(%7.7s)\n%s", tipc_own_id_string(net),
                tipc_crypto_key_dump(tx, buf));

        rcu_read_lock();
        for (p = tn->node_list.next; p != &tn->node_list; p = p->next) {
                rx = tipc_node_crypto_rx_by_list(p);
                pr_info("RX(%7.7s)\n%s", tipc_node_get_id_str(rx->node),
                        tipc_crypto_key_dump(rx, buf));
        }
        rcu_read_unlock();

        /* Print crypto statistics */
        for (i = 0, j = 0; i < MAX_STATS; i++)
                j += scnprintf(buf + j, 200 - j, "|%11s ", hstats[i]);
        pr_info("\nCounter     %s", buf);

        memset(buf, '-', 115);
        buf[115] = '\0';
        pr_info("%s\n", buf);

        j = scnprintf(buf, 200, "TX(%7.7s) ", tipc_own_id_string(net));
        for_each_possible_cpu(cpu) {
                for (i = 0; i < MAX_STATS; i++) {
                        stat = per_cpu_ptr(tx->stats, cpu)->stat[i];
                        j += scnprintf(buf + j, 200 - j, "|%11d ", stat);
                }
                pr_info("%s", buf);
                j = scnprintf(buf, 200, "%12s", " ");
        }

        rcu_read_lock();
        for (p = tn->node_list.next; p != &tn->node_list; p = p->next) {
                rx = tipc_node_crypto_rx_by_list(p);
                j = scnprintf(buf, 200, "RX(%7.7s) ",
                              tipc_node_get_id_str(rx->node));
                for_each_possible_cpu(cpu) {
                        for (i = 0; i < MAX_STATS; i++) {
                                stat = per_cpu_ptr(rx->stats, cpu)->stat[i];
                                j += scnprintf(buf + j, 200 - j, "|%11d ",
                                               stat);
                        }
                        pr_info("%s", buf);
                        j = scnprintf(buf, 200, "%12s", " ");
                }
        }
        rcu_read_unlock();

        pr_info("\n======================== Done ========================\n");
}

static char *tipc_crypto_key_dump(struct tipc_crypto *c, char *buf)
{
        struct tipc_key key = c->key;
        struct tipc_aead *aead;
        int k, i = 0;
        char *s;

        for (k = KEY_MIN; k <= KEY_MAX; k++) {
                if (k == key.passive)
                        s = "PAS";
                else if (k == key.active)
                        s = "ACT";
                else if (k == key.pending)
                        s = "PEN";
                else
                        s = "-";
                i += scnprintf(buf + i, 200 - i, "\tKey%d: %s", k, s);

                rcu_read_lock();
                aead = rcu_dereference(c->aead[k]);
                if (aead)
                        i += scnprintf(buf + i, 200 - i,
                                       "{\"%s...\", \"%s\"}/%d:%d",
                                       aead->hint,
                                       (aead->mode == CLUSTER_KEY) ? "c" : "p",
                                       atomic_read(&aead->users),
                                       refcount_read(&aead->refcnt));
                rcu_read_unlock();
                i += scnprintf(buf + i, 200 - i, "\n");
        }

        if (c->node)
                i += scnprintf(buf + i, 200 - i, "\tPeer RX active: %d\n",
                               atomic_read(&c->peer_rx_active));

        return buf;
}

#ifdef TIPC_CRYPTO_DEBUG
static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
                                  char *buf)
{
        struct tipc_key *key = &old;
        int k, i = 0;
        char *s;

        /* Output format: "[%s %s %s] -> [%s %s %s]", max len = 32 */
again:
        i += scnprintf(buf + i, 32 - i, "[");
        for (k = KEY_MIN; k <= KEY_MAX; k++) {
                if (k == key->passive)
                        s = "pas";
                else if (k == key->active)
                        s = "act";
                else if (k == key->pending)
                        s = "pen";
                else
                        s = "-";
                i += scnprintf(buf + i, 32 - i,
                               (k != KEY_MAX) ? "%s " : "%s", s);
        }
        if (key != &new) {
                i += scnprintf(buf + i, 32 - i, "] -> ");
                key = &new;
                goto again;
        }
        i += scnprintf(buf + i, 32 - i, "]");
        return buf;
}
#endif