diff options
Diffstat (limited to 'net/netfilter/xt_TCPMSS.c')
| -rw-r--r-- | net/netfilter/xt_TCPMSS.c | 31 |
1 files changed, 17 insertions, 14 deletions
diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c index eda64c1cb1e5..c5f4b9919e9a 100644 --- a/net/netfilter/xt_TCPMSS.c +++ b/net/netfilter/xt_TCPMSS.c @@ -11,6 +11,7 @@ #include <linux/module.h> #include <linux/skbuff.h> #include <linux/ip.h> +#include <linux/gfp.h> #include <linux/ipv6.h> #include <linux/tcp.h> #include <net/dst.h> @@ -60,17 +61,9 @@ tcpmss_mangle_packet(struct sk_buff *skb, tcplen = skb->len - tcphoff; tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff); - /* Since it passed flags test in tcp match, we know it is is - not a fragment, and has data >= tcp header length. SYN - packets should not contain data: if they did, then we risk - running over MTU, sending Frag Needed and breaking things - badly. --RR */ - if (tcplen != tcph->doff*4) { - if (net_ratelimit()) - printk(KERN_ERR "xt_TCPMSS: bad length (%u bytes)\n", - skb->len); + /* Header cannot be larger than the packet */ + if (tcplen < tcph->doff*4) return -1; - } if (info->mss == XT_TCPMSS_CLAMP_PMTU) { if (dst_mtu(skb_dst(skb)) <= minlen) { @@ -115,6 +108,12 @@ tcpmss_mangle_packet(struct sk_buff *skb, } } + /* There is data after the header so the option can't be added + without moving it, and doing so may make the SYN packet + itself too large. Accept the packet unmodified instead. */ + if (tcplen > tcph->doff*4) + return 0; + /* * MSS Option not found ?! add it.. */ @@ -241,6 +240,7 @@ static bool tcpmss_tg4_check(const struct xt_tgchk_param *par) { const struct xt_tcpmss_info *info = par->targinfo; const struct ipt_entry *e = par->entryinfo; + const struct xt_entry_match *ematch; if (info->mss == XT_TCPMSS_CLAMP_PMTU && (par->hook_mask & ~((1 << NF_INET_FORWARD) | @@ -250,8 +250,9 @@ static bool tcpmss_tg4_check(const struct xt_tgchk_param *par) "FORWARD, OUTPUT and POSTROUTING hooks\n"); return false; } - if (IPT_MATCH_ITERATE(e, find_syn_match)) - return true; + xt_ematch_foreach(ematch, e) + if (find_syn_match(ematch)) + return true; printk("xt_TCPMSS: Only works on TCP SYN packets\n"); return false; } @@ -261,6 +262,7 @@ static bool tcpmss_tg6_check(const struct xt_tgchk_param *par) { const struct xt_tcpmss_info *info = par->targinfo; const struct ip6t_entry *e = par->entryinfo; + const struct xt_entry_match *ematch; if (info->mss == XT_TCPMSS_CLAMP_PMTU && (par->hook_mask & ~((1 << NF_INET_FORWARD) | @@ -270,8 +272,9 @@ static bool tcpmss_tg6_check(const struct xt_tgchk_param *par) "FORWARD, OUTPUT and POSTROUTING hooks\n"); return false; } - if (IP6T_MATCH_ITERATE(e, find_syn_match)) - return true; + xt_ematch_foreach(ematch, e) + if (find_syn_match(ematch)) + return true; printk("xt_TCPMSS: Only works on TCP SYN packets\n"); return false; } |