xfrm_output.c

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/*
 * xfrm_output.c - Common IPsec encapsulation code.
 *
 * Copyright (c) 2007 Herbert Xu <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <net/dst.h>
#include <net/xfrm.h>

static int xfrm_output2(struct sk_buff *skb);

static int xfrm_skb_check_space(struct sk_buff *skb)
{
    struct dst_entry *dst = skb_dst(skb);
    int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
        - skb_headroom(skb);
    int ntail = dst->dev->needed_tailroom - skb_tailroom(skb);

    if (nhead <= 0) {
        if (ntail <= 0)
            return 0;
        nhead = 0;
    } else if (ntail < 0)
        ntail = 0;

    return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC);
}

static int xfrm_output_one(struct sk_buff *skb, int err)
{
    struct dst_entry *dst = skb_dst(skb);
    struct xfrm_state *x = dst->xfrm;
    struct net *net = xs_net(x);

    if (err <= 0)
        goto resume;

    do {
        err = xfrm_skb_check_space(skb);
        if (err) {
            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
            goto error_nolock;
        }

        err = x->outer_mode->output(x, skb);
        if (err) {
            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
            goto error_nolock;
        }

        spin_lock_bh(&x->lock);
        err = xfrm_state_check_expire(x);
        if (err) {
            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
            goto error;
        }

        err = x->repl->overflow(x, skb);
        if (err) {
            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
            goto error;
        }

        x->curlft.bytes += skb->len;
        x->curlft.packets++;

        spin_unlock_bh(&x->lock);

        skb_dst_force(skb);

        err = x->type->output(x, skb);
        if (err == -EINPROGRESS)
            goto out_exit;

resume:
        if (err) {
            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
            goto error_nolock;
        }

        dst = skb_dst_pop(skb);
        if (!dst) {
            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
            err = -EHOSTUNREACH;
            goto error_nolock;
        }
        skb_dst_set(skb, dst);
        x = dst->xfrm;
    } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));

    err = 0;

out_exit:
    return err;
error:
    spin_unlock_bh(&x->lock);
error_nolock:
    kfree_skb(skb);
    goto out_exit;
}

int xfrm_output_resume(struct sk_buff *skb, int err)
{
    while (likely((err = xfrm_output_one(skb, err)) == 0)) {
        nf_reset(skb);

        err = skb_dst(skb)->ops->local_out(skb);
        if (unlikely(err != 1))
            goto out;

        if (!skb_dst(skb)->xfrm)
            return dst_output(skb);

        err = nf_hook(skb_dst(skb)->ops->family,
                  NF_INET_POST_ROUTING, skb,
                  NULL, skb_dst(skb)->dev, xfrm_output2);
        if (unlikely(err != 1))
            goto out;
    }

    if (err == -EINPROGRESS)
        err = 0;

out:
    return err;
}
EXPORT_SYMBOL_GPL(xfrm_output_resume);

static int xfrm_output2(struct sk_buff *skb)
{
    return xfrm_output_resume(skb, 1);
}

static int xfrm_output_gso(struct sk_buff *skb)
{
    struct sk_buff *segs;

    segs = skb_gso_segment(skb, 0);
    kfree_skb(skb);
    if (IS_ERR(segs))
        return PTR_ERR(segs);

    do {
        struct sk_buff *nskb = segs->next;
        int err;

        segs->next = NULL;
        err = xfrm_output2(segs);

        if (unlikely(err)) {
            while ((segs = nskb)) {
                nskb = segs->next;
                segs->next = NULL;
                kfree_skb(segs);
            }
            return err;
        }

        segs = nskb;
    } while (segs);

    return 0;
}

int xfrm_output(struct sk_buff *skb)
{
    struct net *net = dev_net(skb_dst(skb)->dev);
    int err;

    if (skb_is_gso(skb))
        return xfrm_output_gso(skb);

    if (skb->ip_summed == CHECKSUM_PARTIAL) {
        err = skb_checksum_help(skb);
        if (err) {
            XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
            kfree_skb(skb);
            return err;
        }
    }

    return xfrm_output2(skb);
}

int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
{
    struct xfrm_mode *inner_mode;
    if (x->sel.family == AF_UNSPEC)
        inner_mode = xfrm_ip2inner_mode(x,
                xfrm_af2proto(skb_dst(skb)->ops->family));
    else
        inner_mode = x->inner_mode;

    if (inner_mode == NULL)
        return -EAFNOSUPPORT;
    return inner_mode->afinfo->extract_output(x, skb);
}

EXPORT_SYMBOL_GPL(xfrm_output);
EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);