X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=net%2Fipv4%2Fnetfilter%2Fipt_TCPMSS.c;h=93eb5c3c1884c3c65297b3e7a8b5e15dd5f30315;hb=97bf2856c6014879bd04983a3e9dfcdac1e7fe85;hp=c122841e182c965d0c8629eb26987af736830001;hpb=76828883507a47dae78837ab5dec5a5b4513c667;p=linux-2.6.git diff --git a/net/ipv4/netfilter/ipt_TCPMSS.c b/net/ipv4/netfilter/ipt_TCPMSS.c index c122841e1..93eb5c3c1 100644 --- a/net/ipv4/netfilter/ipt_TCPMSS.c +++ b/net/ipv4/netfilter/ipt_TCPMSS.c @@ -21,26 +21,14 @@ MODULE_LICENSE("GPL"); MODULE_AUTHOR("Marc Boucher "); MODULE_DESCRIPTION("iptables TCP MSS modification module"); -#if 0 -#define DEBUGP printk -#else -#define DEBUGP(format, args...) -#endif - -static u_int16_t -cheat_check(u_int32_t oldvalinv, u_int32_t newval, u_int16_t oldcheck) -{ - u_int32_t diffs[] = { oldvalinv, newval }; - return csum_fold(csum_partial((char *)diffs, sizeof(diffs), - oldcheck^0xFFFF)); -} - static inline unsigned int optlen(const u_int8_t *opt, unsigned int offset) { /* Beware zero-length options: make finite progress */ - if (opt[offset] <= TCPOPT_NOP || opt[offset+1] == 0) return 1; - else return opt[offset+1]; + if (opt[offset] <= TCPOPT_NOP || opt[offset+1] == 0) + return 1; + else + return opt[offset+1]; } static unsigned int @@ -48,26 +36,22 @@ ipt_tcpmss_target(struct sk_buff **pskb, const struct net_device *in, const struct net_device *out, unsigned int hooknum, - const void *targinfo, - void *userinfo) + const struct xt_target *target, + const void *targinfo) { const struct ipt_tcpmss_info *tcpmssinfo = targinfo; struct tcphdr *tcph; struct iphdr *iph; - u_int16_t tcplen, newtotlen, oldval, newmss; + u_int16_t tcplen, newmss; + __be16 newtotlen, oldval; unsigned int i; u_int8_t *opt; if (!skb_make_writable(pskb, (*pskb)->len)) return NF_DROP; - if ((*pskb)->ip_summed == CHECKSUM_HW && - skb_checksum_help(*pskb, out == NULL)) - return NF_DROP; - iph = (*pskb)->nh.iph; tcplen = (*pskb)->len - iph->ihl*4; - tcph = (void *)iph + iph->ihl*4; /* Since it passed flags test in tcp match, we know it is is @@ -83,54 +67,39 @@ ipt_tcpmss_target(struct sk_buff **pskb, return NF_DROP; } - if(tcpmssinfo->mss == IPT_TCPMSS_CLAMP_PMTU) { - if(!(*pskb)->dst) { - if (net_ratelimit()) - printk(KERN_ERR - "ipt_tcpmss_target: no dst?! can't determine path-MTU\n"); - return NF_DROP; /* or IPT_CONTINUE ?? */ - } - - if(dst_mtu((*pskb)->dst) <= (sizeof(struct iphdr) + sizeof(struct tcphdr))) { + if (tcpmssinfo->mss == IPT_TCPMSS_CLAMP_PMTU) { + if (dst_mtu((*pskb)->dst) <= sizeof(struct iphdr) + + sizeof(struct tcphdr)) { if (net_ratelimit()) - printk(KERN_ERR - "ipt_tcpmss_target: unknown or invalid path-MTU (%d)\n", dst_mtu((*pskb)->dst)); + printk(KERN_ERR "ipt_tcpmss_target: " + "unknown or invalid path-MTU (%d)\n", + dst_mtu((*pskb)->dst)); return NF_DROP; /* or IPT_CONTINUE ?? */ } - newmss = dst_mtu((*pskb)->dst) - sizeof(struct iphdr) - sizeof(struct tcphdr); + newmss = dst_mtu((*pskb)->dst) - sizeof(struct iphdr) - + sizeof(struct tcphdr); } else newmss = tcpmssinfo->mss; opt = (u_int8_t *)tcph; - for (i = sizeof(struct tcphdr); i < tcph->doff*4; i += optlen(opt, i)){ - if ((opt[i] == TCPOPT_MSS) && - ((tcph->doff*4 - i) >= TCPOLEN_MSS) && - (opt[i+1] == TCPOLEN_MSS)) { + for (i = sizeof(struct tcphdr); i < tcph->doff*4; i += optlen(opt, i)) { + if (opt[i] == TCPOPT_MSS && tcph->doff*4 - i >= TCPOLEN_MSS && + opt[i+1] == TCPOLEN_MSS) { u_int16_t oldmss; oldmss = (opt[i+2] << 8) | opt[i+3]; - if((tcpmssinfo->mss == IPT_TCPMSS_CLAMP_PMTU) && - (oldmss <= newmss)) - return IPT_CONTINUE; + if (tcpmssinfo->mss == IPT_TCPMSS_CLAMP_PMTU && + oldmss <= newmss) + return IPT_CONTINUE; opt[i+2] = (newmss & 0xff00) >> 8; opt[i+3] = (newmss & 0x00ff); - tcph->check = cheat_check(htons(oldmss)^0xFFFF, - htons(newmss), - tcph->check); - - DEBUGP(KERN_INFO "ipt_tcpmss_target: %u.%u.%u.%u:%hu" - "->%u.%u.%u.%u:%hu changed TCP MSS option" - " (from %u to %u)\n", - NIPQUAD((*pskb)->nh.iph->saddr), - ntohs(tcph->source), - NIPQUAD((*pskb)->nh.iph->daddr), - ntohs(tcph->dest), - oldmss, newmss); - goto retmodified; + nf_proto_csum_replace2(&tcph->check, *pskb, + htons(oldmss), htons(newmss), 0); + return IPT_CONTINUE; } } @@ -142,13 +111,8 @@ ipt_tcpmss_target(struct sk_buff **pskb, newskb = skb_copy_expand(*pskb, skb_headroom(*pskb), TCPOLEN_MSS, GFP_ATOMIC); - if (!newskb) { - if (net_ratelimit()) - printk(KERN_ERR "ipt_tcpmss_target:" - " unable to allocate larger skb\n"); + if (!newskb) return NF_DROP; - } - kfree_skb(*pskb); *pskb = newskb; iph = (*pskb)->nh.iph; @@ -160,36 +124,23 @@ ipt_tcpmss_target(struct sk_buff **pskb, opt = (u_int8_t *)tcph + sizeof(struct tcphdr); memmove(opt + TCPOLEN_MSS, opt, tcplen - sizeof(struct tcphdr)); - tcph->check = cheat_check(htons(tcplen) ^ 0xFFFF, - htons(tcplen + TCPOLEN_MSS), tcph->check); - tcplen += TCPOLEN_MSS; - + nf_proto_csum_replace2(&tcph->check, *pskb, + htons(tcplen), htons(tcplen + TCPOLEN_MSS), 1); opt[0] = TCPOPT_MSS; opt[1] = TCPOLEN_MSS; opt[2] = (newmss & 0xff00) >> 8; opt[3] = (newmss & 0x00ff); - tcph->check = cheat_check(~0, *((u_int32_t *)opt), tcph->check); + nf_proto_csum_replace4(&tcph->check, *pskb, 0, *((__be32 *)opt), 0); - oldval = ((u_int16_t *)tcph)[6]; + oldval = ((__be16 *)tcph)[6]; tcph->doff += TCPOLEN_MSS/4; - tcph->check = cheat_check(oldval ^ 0xFFFF, - ((u_int16_t *)tcph)[6], tcph->check); + nf_proto_csum_replace2(&tcph->check, *pskb, + oldval, ((__be16 *)tcph)[6], 0); newtotlen = htons(ntohs(iph->tot_len) + TCPOLEN_MSS); - iph->check = cheat_check(iph->tot_len ^ 0xFFFF, - newtotlen, iph->check); + nf_csum_replace2(&iph->check, iph->tot_len, newtotlen); iph->tot_len = newtotlen; - - DEBUGP(KERN_INFO "ipt_tcpmss_target: %u.%u.%u.%u:%hu" - "->%u.%u.%u.%u:%hu added TCP MSS option (%u)\n", - NIPQUAD((*pskb)->nh.iph->saddr), - ntohs(tcph->source), - NIPQUAD((*pskb)->nh.iph->daddr), - ntohs(tcph->dest), - newmss); - - retmodified: return IPT_CONTINUE; } @@ -199,9 +150,9 @@ static inline int find_syn_match(const struct ipt_entry_match *m) { const struct ipt_tcp *tcpinfo = (const struct ipt_tcp *)m->data; - if (strcmp(m->u.kernel.match->name, "tcp") == 0 - && (tcpinfo->flg_cmp & TH_SYN) - && !(tcpinfo->invflags & IPT_TCP_INV_FLAGS)) + if (strcmp(m->u.kernel.match->name, "tcp") == 0 && + tcpinfo->flg_cmp & TH_SYN && + !(tcpinfo->invflags & IPT_TCP_INV_FLAGS)) return 1; return 0; @@ -211,33 +162,24 @@ static inline int find_syn_match(const struct ipt_entry_match *m) static int ipt_tcpmss_checkentry(const char *tablename, const void *e_void, + const struct xt_target *target, void *targinfo, - unsigned int targinfosize, unsigned int hook_mask) { const struct ipt_tcpmss_info *tcpmssinfo = targinfo; const struct ipt_entry *e = e_void; - if (targinfosize != IPT_ALIGN(sizeof(struct ipt_tcpmss_info))) { - DEBUGP("ipt_tcpmss_checkentry: targinfosize %u != %u\n", - targinfosize, IPT_ALIGN(sizeof(struct ipt_tcpmss_info))); + if (tcpmssinfo->mss == IPT_TCPMSS_CLAMP_PMTU && + (hook_mask & ~((1 << NF_IP_FORWARD) | + (1 << NF_IP_LOCAL_OUT) | + (1 << NF_IP_POST_ROUTING))) != 0) { + printk("TCPMSS: path-MTU clamping only supported in " + "FORWARD, OUTPUT and POSTROUTING hooks\n"); return 0; } - - if((tcpmssinfo->mss == IPT_TCPMSS_CLAMP_PMTU) && - ((hook_mask & ~((1 << NF_IP_FORWARD) - | (1 << NF_IP_LOCAL_OUT) - | (1 << NF_IP_POST_ROUTING))) != 0)) { - printk("TCPMSS: path-MTU clamping only supported in FORWARD, OUTPUT and POSTROUTING hooks\n"); - return 0; - } - - if (e->ip.proto == IPPROTO_TCP - && !(e->ip.invflags & IPT_INV_PROTO) - && IPT_MATCH_ITERATE(e, find_syn_match)) + if (IPT_MATCH_ITERATE(e, find_syn_match)) return 1; - printk("TCPMSS: Only works on TCP SYN packets\n"); return 0; } @@ -245,19 +187,21 @@ ipt_tcpmss_checkentry(const char *tablename, static struct ipt_target ipt_tcpmss_reg = { .name = "TCPMSS", .target = ipt_tcpmss_target, + .targetsize = sizeof(struct ipt_tcpmss_info), + .proto = IPPROTO_TCP, .checkentry = ipt_tcpmss_checkentry, .me = THIS_MODULE, }; -static int __init init(void) +static int __init ipt_tcpmss_init(void) { return ipt_register_target(&ipt_tcpmss_reg); } -static void __exit fini(void) +static void __exit ipt_tcpmss_fini(void) { ipt_unregister_target(&ipt_tcpmss_reg); } -module_init(init); -module_exit(fini); +module_init(ipt_tcpmss_init); +module_exit(ipt_tcpmss_fini);