// SPDX-License-Identifier: GPL-2.0
/*
 * XFRM compat layer
 * Author: Dmitry Safonov <dima@arista.com>
 * Based on code and translator idea by: Florian Westphal <fw@strlen.de>
 */
#include <linux/compat.h>
#include <linux/nospec.h>
#include <linux/xfrm.h>
#include <net/xfrm.h>

struct compat_xfrm_lifetime_cfg {
        compat_u64 soft_byte_limit, hard_byte_limit;
        compat_u64 soft_packet_limit, hard_packet_limit;
        compat_u64 soft_add_expires_seconds, hard_add_expires_seconds;
        compat_u64 soft_use_expires_seconds, hard_use_expires_seconds;
}; /* same size on 32bit, but only 4 byte alignment required */

struct compat_xfrm_lifetime_cur {
        compat_u64 bytes, packets, add_time, use_time;
}; /* same size on 32bit, but only 4 byte alignment required */

struct compat_xfrm_userpolicy_info {
        struct xfrm_selector sel;
        struct compat_xfrm_lifetime_cfg lft;
        struct compat_xfrm_lifetime_cur curlft;
        __u32 priority, index;
        u8 dir, action, flags, share;
        /* 4 bytes additional padding on 64bit */
};

struct compat_xfrm_usersa_info {
        struct xfrm_selector sel;
        struct xfrm_id id;
        xfrm_address_t saddr;
        struct compat_xfrm_lifetime_cfg lft;
        struct compat_xfrm_lifetime_cur curlft;
        struct xfrm_stats stats;
        __u32 seq, reqid;
        u16 family;
        u8 mode, replay_window, flags;
        /* 4 bytes additional padding on 64bit */
};

struct compat_xfrm_user_acquire {
        struct xfrm_id id;
        xfrm_address_t saddr;
        struct xfrm_selector sel;
        struct compat_xfrm_userpolicy_info policy;
        /* 4 bytes additional padding on 64bit */
        __u32 aalgos, ealgos, calgos, seq;
};

struct compat_xfrm_userspi_info {
        struct compat_xfrm_usersa_info info;
        /* 4 bytes additional padding on 64bit */
        __u32 min, max;
};

struct compat_xfrm_user_expire {
        struct compat_xfrm_usersa_info state;
        /* 8 bytes additional padding on 64bit */
        u8 hard;
};

struct compat_xfrm_user_polexpire {
        struct compat_xfrm_userpolicy_info pol;
        /* 8 bytes additional padding on 64bit */
        u8 hard;
};

#define XMSGSIZE(type) sizeof(struct type)

static const int compat_msg_min[XFRM_NR_MSGTYPES] = {
        [XFRM_MSG_NEWSA       - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_usersa_info),
        [XFRM_MSG_DELSA       - XFRM_MSG_BASE] = XMSGSIZE(xfrm_usersa_id),
        [XFRM_MSG_GETSA       - XFRM_MSG_BASE] = XMSGSIZE(xfrm_usersa_id),
        [XFRM_MSG_NEWPOLICY   - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_userpolicy_info),
        [XFRM_MSG_DELPOLICY   - XFRM_MSG_BASE] = XMSGSIZE(xfrm_userpolicy_id),
        [XFRM_MSG_GETPOLICY   - XFRM_MSG_BASE] = XMSGSIZE(xfrm_userpolicy_id),
        [XFRM_MSG_ALLOCSPI    - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_userspi_info),
        [XFRM_MSG_ACQUIRE     - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_user_acquire),
        [XFRM_MSG_EXPIRE      - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_user_expire),
        [XFRM_MSG_UPDPOLICY   - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_userpolicy_info),
        [XFRM_MSG_UPDSA       - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_usersa_info),
        [XFRM_MSG_POLEXPIRE   - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_user_polexpire),
        [XFRM_MSG_FLUSHSA     - XFRM_MSG_BASE] = XMSGSIZE(xfrm_usersa_flush),
        [XFRM_MSG_FLUSHPOLICY - XFRM_MSG_BASE] = 0,
        [XFRM_MSG_NEWAE       - XFRM_MSG_BASE] = XMSGSIZE(xfrm_aevent_id),
        [XFRM_MSG_GETAE       - XFRM_MSG_BASE] = XMSGSIZE(xfrm_aevent_id),
        [XFRM_MSG_REPORT      - XFRM_MSG_BASE] = XMSGSIZE(xfrm_user_report),
        [XFRM_MSG_MIGRATE     - XFRM_MSG_BASE] = XMSGSIZE(xfrm_userpolicy_id),
        [XFRM_MSG_NEWSADINFO  - XFRM_MSG_BASE] = sizeof(u32),
        [XFRM_MSG_GETSADINFO  - XFRM_MSG_BASE] = sizeof(u32),
        [XFRM_MSG_NEWSPDINFO  - XFRM_MSG_BASE] = sizeof(u32),
        [XFRM_MSG_GETSPDINFO  - XFRM_MSG_BASE] = sizeof(u32),
        [XFRM_MSG_MAPPING        - XFRM_MSG_BASE] = XMSGSIZE(xfrm_user_mapping),
        [XFRM_MSG_MIGRATE_STATE  - XFRM_MSG_BASE] = XMSGSIZE(xfrm_user_migrate_state),
};

static const struct nla_policy compat_policy[XFRMA_MAX+1] = {
        [XFRMA_UNSPEC]          = { .strict_start_type = XFRMA_SA_DIR },
        [XFRMA_SA]              = { .len = XMSGSIZE(compat_xfrm_usersa_info)},
        [XFRMA_POLICY]          = { .len = XMSGSIZE(compat_xfrm_userpolicy_info)},
        [XFRMA_LASTUSED]        = { .type = NLA_U64},
        [XFRMA_ALG_AUTH_TRUNC]  = { .len = sizeof(struct xfrm_algo_auth)},
        [XFRMA_ALG_AEAD]        = { .len = sizeof(struct xfrm_algo_aead) },
        [XFRMA_ALG_AUTH]        = { .len = sizeof(struct xfrm_algo) },
        [XFRMA_ALG_CRYPT]       = { .len = sizeof(struct xfrm_algo) },
        [XFRMA_ALG_COMP]        = { .len = sizeof(struct xfrm_algo) },
        [XFRMA_ENCAP]           = { .len = sizeof(struct xfrm_encap_tmpl) },
        [XFRMA_TMPL]            = { .len = sizeof(struct xfrm_user_tmpl) },
        [XFRMA_SEC_CTX]         = { .len = sizeof(struct xfrm_user_sec_ctx) },
        [XFRMA_LTIME_VAL]       = { .len = sizeof(struct xfrm_lifetime_cur) },
        [XFRMA_REPLAY_VAL]      = { .len = sizeof(struct xfrm_replay_state) },
        [XFRMA_REPLAY_THRESH]   = { .type = NLA_U32 },
        [XFRMA_ETIMER_THRESH]   = { .type = NLA_U32 },
        [XFRMA_SRCADDR]         = { .len = sizeof(xfrm_address_t) },
        [XFRMA_COADDR]          = { .len = sizeof(xfrm_address_t) },
        [XFRMA_POLICY_TYPE]     = { .len = sizeof(struct xfrm_userpolicy_type)},
        [XFRMA_MIGRATE]         = { .len = sizeof(struct xfrm_user_migrate) },
        [XFRMA_KMADDRESS]       = { .len = sizeof(struct xfrm_user_kmaddress) },
        [XFRMA_MARK]            = { .len = sizeof(struct xfrm_mark) },
        [XFRMA_TFCPAD]          = { .type = NLA_U32 },
        [XFRMA_REPLAY_ESN_VAL]  = { .len = sizeof(struct xfrm_replay_state_esn) },
        [XFRMA_SA_EXTRA_FLAGS]  = { .type = NLA_U32 },
        [XFRMA_PROTO]           = { .type = NLA_U8 },
        [XFRMA_ADDRESS_FILTER]  = { .len = sizeof(struct xfrm_address_filter) },
        [XFRMA_OFFLOAD_DEV]     = { .len = sizeof(struct xfrm_user_offload) },
        [XFRMA_SET_MARK]        = { .type = NLA_U32 },
        [XFRMA_SET_MARK_MASK]   = { .type = NLA_U32 },
        [XFRMA_IF_ID]           = { .type = NLA_U32 },
        [XFRMA_MTIMER_THRESH]   = { .type = NLA_U32 },
        [XFRMA_SA_DIR]          = NLA_POLICY_RANGE(NLA_U8, XFRM_SA_DIR_IN, XFRM_SA_DIR_OUT),
        [XFRMA_NAT_KEEPALIVE_INTERVAL]  = { .type = NLA_U32 },
        [XFRMA_SA_PCPU]         = { .type = NLA_U32 },
};

static struct nlmsghdr *xfrm_nlmsg_put_compat(struct sk_buff *skb,
                        const struct nlmsghdr *nlh_src, u16 type)
{
        int payload = compat_msg_min[type];
        int src_len = xfrm_msg_min[type];
        struct nlmsghdr *nlh_dst;

        /* Compat messages are shorter or equal to native (+padding) */
        if (WARN_ON_ONCE(src_len < payload))
                return ERR_PTR(-EMSGSIZE);

        nlh_dst = nlmsg_put(skb, nlh_src->nlmsg_pid, nlh_src->nlmsg_seq,
                            nlh_src->nlmsg_type, payload, nlh_src->nlmsg_flags);
        if (!nlh_dst)
                return ERR_PTR(-EMSGSIZE);

        memset(nlmsg_data(nlh_dst), 0, payload);

        switch (nlh_src->nlmsg_type) {
        /* Compat message has the same layout as native */
        case XFRM_MSG_DELSA:
        case XFRM_MSG_DELPOLICY:
        case XFRM_MSG_FLUSHSA:
        case XFRM_MSG_FLUSHPOLICY:
        case XFRM_MSG_NEWAE:
        case XFRM_MSG_REPORT:
        case XFRM_MSG_MIGRATE:
        case XFRM_MSG_MIGRATE_STATE:
        case XFRM_MSG_NEWSADINFO:
        case XFRM_MSG_NEWSPDINFO:
        case XFRM_MSG_MAPPING:
                WARN_ON_ONCE(src_len != payload);
                memcpy(nlmsg_data(nlh_dst), nlmsg_data(nlh_src), src_len);
                break;
        /* 4 byte alignment for trailing u64 on native, but not on compat */
        case XFRM_MSG_NEWSA:
        case XFRM_MSG_NEWPOLICY:
        case XFRM_MSG_UPDSA:
        case XFRM_MSG_UPDPOLICY:
                WARN_ON_ONCE(src_len != payload + 4);
                memcpy(nlmsg_data(nlh_dst), nlmsg_data(nlh_src), payload);
                break;
        case XFRM_MSG_EXPIRE: {
                const struct xfrm_user_expire *src_ue  = nlmsg_data(nlh_src);
                struct compat_xfrm_user_expire *dst_ue = nlmsg_data(nlh_dst);

                /* compat_xfrm_user_expire has 4-byte smaller state */
                memcpy(dst_ue, src_ue, sizeof(dst_ue->state));
                dst_ue->hard = src_ue->hard;
                break;
        }
        case XFRM_MSG_ACQUIRE: {
                const struct xfrm_user_acquire *src_ua  = nlmsg_data(nlh_src);
                struct compat_xfrm_user_acquire *dst_ua = nlmsg_data(nlh_dst);

                memcpy(dst_ua, src_ua, offsetof(struct compat_xfrm_user_acquire, aalgos));
                dst_ua->aalgos = src_ua->aalgos;
                dst_ua->ealgos = src_ua->ealgos;
                dst_ua->calgos = src_ua->calgos;
                dst_ua->seq    = src_ua->seq;
                break;
        }
        case XFRM_MSG_POLEXPIRE: {
                const struct xfrm_user_polexpire *src_upe  = nlmsg_data(nlh_src);
                struct compat_xfrm_user_polexpire *dst_upe = nlmsg_data(nlh_dst);

                /* compat_xfrm_user_polexpire has 4-byte smaller state */
                memcpy(dst_upe, src_upe, sizeof(dst_upe->pol));
                dst_upe->hard = src_upe->hard;
                break;
        }
        case XFRM_MSG_ALLOCSPI: {
                const struct xfrm_userspi_info *src_usi = nlmsg_data(nlh_src);
                struct compat_xfrm_userspi_info *dst_usi = nlmsg_data(nlh_dst);

                /* compat_xfrm_user_polexpire has 4-byte smaller state */
                memcpy(dst_usi, src_usi, sizeof(src_usi->info));
                dst_usi->min = src_usi->min;
                dst_usi->max = src_usi->max;
                break;
        }
        /* Not being sent by kernel */
        case XFRM_MSG_GETSA:
        case XFRM_MSG_GETPOLICY:
        case XFRM_MSG_GETAE:
        case XFRM_MSG_GETSADINFO:
        case XFRM_MSG_GETSPDINFO:
        default:
                pr_warn_once("unsupported nlmsg_type %d\n", nlh_src->nlmsg_type);
                return ERR_PTR(-EOPNOTSUPP);
        }

        return nlh_dst;
}

static int xfrm_nla_cpy(struct sk_buff *dst, const struct nlattr *src, int len)
{
        return nla_put(dst, src->nla_type, len, nla_data(src));
}

static int xfrm_xlate64_attr(struct sk_buff *dst, const struct nlattr *src)
{
        switch (src->nla_type) {
        case XFRMA_PAD:
                /* Ignore */
                return 0;
        case XFRMA_UNSPEC:
        case XFRMA_ALG_AUTH:
        case XFRMA_ALG_CRYPT:
        case XFRMA_ALG_COMP:
        case XFRMA_ENCAP:
        case XFRMA_TMPL:
                return xfrm_nla_cpy(dst, src, nla_len(src));
        case XFRMA_SA:
                return xfrm_nla_cpy(dst, src, XMSGSIZE(compat_xfrm_usersa_info));
        case XFRMA_POLICY:
                return xfrm_nla_cpy(dst, src, XMSGSIZE(compat_xfrm_userpolicy_info));
        case XFRMA_SEC_CTX:
                return xfrm_nla_cpy(dst, src, nla_len(src));
        case XFRMA_LTIME_VAL:
                return nla_put_64bit(dst, src->nla_type, nla_len(src),
                        nla_data(src), XFRMA_PAD);
        case XFRMA_REPLAY_VAL:
        case XFRMA_REPLAY_THRESH:
        case XFRMA_ETIMER_THRESH:
        case XFRMA_SRCADDR:
        case XFRMA_COADDR:
                return xfrm_nla_cpy(dst, src, nla_len(src));
        case XFRMA_LASTUSED:
                return nla_put_64bit(dst, src->nla_type, nla_len(src),
                        nla_data(src), XFRMA_PAD);
        case XFRMA_POLICY_TYPE:
        case XFRMA_MIGRATE:
        case XFRMA_ALG_AEAD:
        case XFRMA_KMADDRESS:
        case XFRMA_ALG_AUTH_TRUNC:
        case XFRMA_MARK:
        case XFRMA_TFCPAD:
        case XFRMA_REPLAY_ESN_VAL:
        case XFRMA_SA_EXTRA_FLAGS:
        case XFRMA_PROTO:
        case XFRMA_ADDRESS_FILTER:
        case XFRMA_OFFLOAD_DEV:
        case XFRMA_SET_MARK:
        case XFRMA_SET_MARK_MASK:
        case XFRMA_IF_ID:
        case XFRMA_MTIMER_THRESH:
        case XFRMA_SA_DIR:
        case XFRMA_NAT_KEEPALIVE_INTERVAL:
        case XFRMA_SA_PCPU:
        case XFRMA_IPTFS_DROP_TIME:
        case XFRMA_IPTFS_REORDER_WINDOW:
        case XFRMA_IPTFS_DONT_FRAG:
        case XFRMA_IPTFS_INIT_DELAY:
        case XFRMA_IPTFS_MAX_QSIZE:
        case XFRMA_IPTFS_PKT_SIZE:
                return xfrm_nla_cpy(dst, src, nla_len(src));
        default:
                BUILD_BUG_ON(XFRMA_MAX != XFRMA_IPTFS_PKT_SIZE);
                pr_warn_once("unsupported nla_type %d\n", src->nla_type);
                return -EOPNOTSUPP;
        }
}

/* Take kernel-built (64bit layout) and create 32bit layout for userspace */
static int xfrm_xlate64(struct sk_buff *dst, const struct nlmsghdr *nlh_src)
{
        u16 type = nlh_src->nlmsg_type - XFRM_MSG_BASE;
        const struct nlattr *nla, *attrs;
        struct nlmsghdr *nlh_dst;
        int len, remaining;

        nlh_dst = xfrm_nlmsg_put_compat(dst, nlh_src, type);
        if (IS_ERR(nlh_dst))
                return PTR_ERR(nlh_dst);

        attrs = nlmsg_attrdata(nlh_src, xfrm_msg_min[type]);
        len = nlmsg_attrlen(nlh_src, xfrm_msg_min[type]);

        nla_for_each_attr(nla, attrs, len, remaining) {
                int err;

                switch (nlh_src->nlmsg_type) {
                case XFRM_MSG_NEWSPDINFO:
                        err = xfrm_nla_cpy(dst, nla, nla_len(nla));
                        break;
                default:
                        err = xfrm_xlate64_attr(dst, nla);
                        break;
                }
                if (err)
                        return err;
        }

        nlmsg_end(dst, nlh_dst);

        return 0;
}

static int xfrm_alloc_compat(struct sk_buff *skb, const struct nlmsghdr *nlh_src)
{
        u16 type = nlh_src->nlmsg_type - XFRM_MSG_BASE;
        struct sk_buff *new = NULL;
        int err;

        if (type >= ARRAY_SIZE(xfrm_msg_min)) {
                pr_warn_once("unsupported nlmsg_type %d\n", nlh_src->nlmsg_type);
                return -EOPNOTSUPP;
        }

        if (skb_shinfo(skb)->frag_list == NULL) {
                new = alloc_skb(skb->len + skb_tailroom(skb), GFP_ATOMIC);
                if (!new)
                        return -ENOMEM;
                skb_shinfo(skb)->frag_list = new;
        }

        err = xfrm_xlate64(skb_shinfo(skb)->frag_list, nlh_src);
        if (err) {
                if (new) {
                        kfree_skb(new);
                        skb_shinfo(skb)->frag_list = NULL;
                }
                return err;
        }

        return 0;
}

/* Calculates len of translated 64-bit message. */
static size_t xfrm_user_rcv_calculate_len64(const struct nlmsghdr *src,
                                            struct nlattr *attrs[XFRMA_MAX + 1],
                                            int maxtype)
{
        size_t len = nlmsg_len(src);

        switch (src->nlmsg_type) {
        case XFRM_MSG_NEWSA:
        case XFRM_MSG_NEWPOLICY:
        case XFRM_MSG_ALLOCSPI:
        case XFRM_MSG_ACQUIRE:
        case XFRM_MSG_UPDPOLICY:
        case XFRM_MSG_UPDSA:
                len += 4;
                break;
        case XFRM_MSG_EXPIRE:
        case XFRM_MSG_POLEXPIRE:
                len += 8;
                break;
        case XFRM_MSG_NEWSPDINFO:
                /* attirbutes are xfrm_spdattr_type_t, not xfrm_attr_type_t */
                return len;
        default:
                break;
        }

        /* Unexpected for anything, but XFRM_MSG_NEWSPDINFO, please
         * correct both 64=>32-bit and 32=>64-bit translators to copy
         * new attributes.
         */
        if (WARN_ON_ONCE(maxtype))
                return len;

        if (attrs[XFRMA_SA])
                len += 4;
        if (attrs[XFRMA_POLICY])
                len += 4;

        /* XXX: some attrs may need to be realigned
         * if !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
         */

        return len;
}

static int xfrm_attr_cpy32(void *dst, size_t *pos, const struct nlattr *src,
                           size_t size, int copy_len, int payload)
{
        struct nlmsghdr *nlmsg = dst;
        struct nlattr *nla;

        /* xfrm_user_rcv_msg_compat() relies on fact that 32-bit messages
         * have the same len or shorted than 64-bit ones.
         * 32-bit translation that is bigger than 64-bit original is unexpected.
         */
        if (WARN_ON_ONCE(copy_len > payload))
                copy_len = payload;

        if (size - *pos < nla_attr_size(payload))
                return -ENOBUFS;

        nla = dst + *pos;

        memcpy(nla, src, nla_attr_size(copy_len));
        nla->nla_len = nla_attr_size(payload);
        *pos += nla_attr_size(copy_len);
        nlmsg->nlmsg_len += nla->nla_len;

        memset(dst + *pos, 0, payload - copy_len);
        *pos += payload - copy_len;

        return 0;
}

static int xfrm_xlate32_attr(void *dst, const struct nlattr *nla,
                             size_t *pos, size_t size,
                             struct netlink_ext_ack *extack)
{
        int type = nla_type(nla);
        u16 pol_len32, pol_len64;
        int err;

        if (type > XFRMA_MAX) {
                BUILD_BUG_ON(XFRMA_MAX != XFRMA_IPTFS_PKT_SIZE);
                NL_SET_ERR_MSG(extack, "Bad attribute");
                return -EOPNOTSUPP;
        }
        type = array_index_nospec(type, XFRMA_MAX + 1);
        if (nla_len(nla) < compat_policy[type].len) {
                NL_SET_ERR_MSG(extack, "Attribute bad length");
                return -EOPNOTSUPP;
        }

        pol_len32 = compat_policy[type].len;
        pol_len64 = xfrma_policy[type].len;

        /* XFRMA_SA and XFRMA_POLICY - need to know how-to translate */
        if (pol_len32 != pol_len64) {
                if (nla_len(nla) != compat_policy[type].len) {
                        NL_SET_ERR_MSG(extack, "Attribute bad length");
                        return -EOPNOTSUPP;
                }
                err = xfrm_attr_cpy32(dst, pos, nla, size, pol_len32, pol_len64);
                if (err)
                        return err;
        }

        return xfrm_attr_cpy32(dst, pos, nla, size, nla_len(nla), nla_len(nla));
}

static int xfrm_xlate32(struct nlmsghdr *dst, const struct nlmsghdr *src,
                        struct nlattr *attrs[XFRMA_MAX+1],
                        size_t size, u8 type, int maxtype,
                        struct netlink_ext_ack *extack)
{
        size_t pos;
        int i;

        memcpy(dst, src, NLMSG_HDRLEN);
        dst->nlmsg_len = NLMSG_HDRLEN + xfrm_msg_min[type];
        memset(nlmsg_data(dst), 0, xfrm_msg_min[type]);

        switch (src->nlmsg_type) {
        /* Compat message has the same layout as native */
        case XFRM_MSG_DELSA:
        case XFRM_MSG_GETSA:
        case XFRM_MSG_DELPOLICY:
        case XFRM_MSG_GETPOLICY:
        case XFRM_MSG_FLUSHSA:
        case XFRM_MSG_FLUSHPOLICY:
        case XFRM_MSG_NEWAE:
        case XFRM_MSG_GETAE:
        case XFRM_MSG_REPORT:
        case XFRM_MSG_MIGRATE:
        case XFRM_MSG_MIGRATE_STATE:
        case XFRM_MSG_NEWSADINFO:
        case XFRM_MSG_GETSADINFO:
        case XFRM_MSG_NEWSPDINFO:
        case XFRM_MSG_GETSPDINFO:
        case XFRM_MSG_MAPPING:
                memcpy(nlmsg_data(dst), nlmsg_data(src), compat_msg_min[type]);
                break;
        /* 4 byte alignment for trailing u64 on native, but not on compat */
        case XFRM_MSG_NEWSA:
        case XFRM_MSG_NEWPOLICY:
        case XFRM_MSG_UPDSA:
        case XFRM_MSG_UPDPOLICY:
                memcpy(nlmsg_data(dst), nlmsg_data(src), compat_msg_min[type]);
                break;
        case XFRM_MSG_EXPIRE: {
                const struct compat_xfrm_user_expire *src_ue = nlmsg_data(src);
                struct xfrm_user_expire *dst_ue = nlmsg_data(dst);

                /* compat_xfrm_user_expire has 4-byte smaller state */
                memcpy(dst_ue, src_ue, sizeof(src_ue->state));
                dst_ue->hard = src_ue->hard;
                break;
        }
        case XFRM_MSG_ACQUIRE: {
                const struct compat_xfrm_user_acquire *src_ua = nlmsg_data(src);
                struct xfrm_user_acquire *dst_ua = nlmsg_data(dst);

                memcpy(dst_ua, src_ua, offsetof(struct compat_xfrm_user_acquire, aalgos));
                dst_ua->aalgos = src_ua->aalgos;
                dst_ua->ealgos = src_ua->ealgos;
                dst_ua->calgos = src_ua->calgos;
                dst_ua->seq    = src_ua->seq;
                break;
        }
        case XFRM_MSG_POLEXPIRE: {
                const struct compat_xfrm_user_polexpire *src_upe = nlmsg_data(src);
                struct xfrm_user_polexpire *dst_upe = nlmsg_data(dst);

                /* compat_xfrm_user_polexpire has 4-byte smaller state */
                memcpy(dst_upe, src_upe, sizeof(src_upe->pol));
                dst_upe->hard = src_upe->hard;
                break;
        }
        case XFRM_MSG_ALLOCSPI: {
                const struct compat_xfrm_userspi_info *src_usi = nlmsg_data(src);
                struct xfrm_userspi_info *dst_usi = nlmsg_data(dst);

                /* compat_xfrm_user_polexpire has 4-byte smaller state */
                memcpy(dst_usi, src_usi, sizeof(src_usi->info));
                dst_usi->min = src_usi->min;
                dst_usi->max = src_usi->max;
                break;
        }
        default:
                NL_SET_ERR_MSG(extack, "Unsupported message type");
                return -EOPNOTSUPP;
        }
        pos = dst->nlmsg_len;

        if (maxtype) {
                /* attirbutes are xfrm_spdattr_type_t, not xfrm_attr_type_t */
                WARN_ON_ONCE(src->nlmsg_type != XFRM_MSG_NEWSPDINFO);

                for (i = 1; i <= maxtype; i++) {
                        int err;

                        if (!attrs[i])
                                continue;

                        /* just copy - no need for translation */
                        err = xfrm_attr_cpy32(dst, &pos, attrs[i], size,
                                        nla_len(attrs[i]), nla_len(attrs[i]));
                        if (err)
                                return err;
                }
                return 0;
        }

        for (i = 1; i < XFRMA_MAX + 1; i++) {
                int err;

                if (i == XFRMA_PAD)
                        continue;

                if (!attrs[i])
                        continue;

                err = xfrm_xlate32_attr(dst, attrs[i], &pos, size, extack);
                if (err)
                        return err;
        }

        return 0;
}

static struct nlmsghdr *xfrm_user_rcv_msg_compat(const struct nlmsghdr *h32,
                        int maxtype, const struct nla_policy *policy,
                        struct netlink_ext_ack *extack)
{
        /* netlink_rcv_skb() checks if a message has full (struct nlmsghdr) */
        u16 type = h32->nlmsg_type - XFRM_MSG_BASE;
        struct nlattr *attrs[XFRMA_MAX+1];
        struct nlmsghdr *h64;
        size_t len;
        int err;

        BUILD_BUG_ON(ARRAY_SIZE(xfrm_msg_min) != ARRAY_SIZE(compat_msg_min));

        if (type >= ARRAY_SIZE(xfrm_msg_min))
                return ERR_PTR(-EINVAL);

        /* Don't call parse: the message might have only nlmsg header */
        if ((h32->nlmsg_type == XFRM_MSG_GETSA ||
             h32->nlmsg_type == XFRM_MSG_GETPOLICY) &&
            (h32->nlmsg_flags & NLM_F_DUMP))
                return NULL;

        err = nlmsg_parse_deprecated(h32, compat_msg_min[type], attrs,
                        maxtype ? : XFRMA_MAX, policy ? : compat_policy, extack);
        if (err < 0)
                return ERR_PTR(err);

        len = xfrm_user_rcv_calculate_len64(h32, attrs, maxtype);
        /* The message doesn't need translation */
        if (len == nlmsg_len(h32))
                return NULL;

        len += NLMSG_HDRLEN;
        h64 = kvmalloc(len, GFP_KERNEL);
        if (!h64)
                return ERR_PTR(-ENOMEM);

        err = xfrm_xlate32(h64, h32, attrs, len, type, maxtype, extack);
        if (err < 0) {
                kvfree(h64);
                return ERR_PTR(err);
        }

        return h64;
}

static int xfrm_user_policy_compat(u8 **pdata32, int optlen)
{
        struct compat_xfrm_userpolicy_info *p = (void *)*pdata32;
        u8 *src_templates, *dst_templates;
        u8 *data64;

        if (optlen < sizeof(*p))
                return -EINVAL;

        data64 = kmalloc_track_caller(optlen + 4, GFP_USER | __GFP_NOWARN);
        if (!data64)
                return -ENOMEM;

        memcpy(data64, *pdata32, sizeof(*p));
        memset(data64 + sizeof(*p), 0, 4);

        src_templates = *pdata32 + sizeof(*p);
        dst_templates = data64 + sizeof(*p) + 4;
        memcpy(dst_templates, src_templates, optlen - sizeof(*p));

        kfree(*pdata32);
        *pdata32 = data64;
        return 0;
}

static struct xfrm_translator xfrm_translator = {
        .owner                          = THIS_MODULE,
        .alloc_compat                   = xfrm_alloc_compat,
        .rcv_msg_compat                 = xfrm_user_rcv_msg_compat,
        .xlate_user_policy_sockptr      = xfrm_user_policy_compat,
};

static int __init xfrm_compat_init(void)
{
        return xfrm_register_translator(&xfrm_translator);
}

static void __exit xfrm_compat_exit(void)
{
        xfrm_unregister_translator(&xfrm_translator);
}

module_init(xfrm_compat_init);
module_exit(xfrm_compat_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Dmitry Safonov");
MODULE_DESCRIPTION("XFRM 32-bit compatibility layer");