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author | Andreas Baumann <mail@andreasbaumann.cc> | 2015-01-03 12:04:58 +0100 |
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committer | Andreas Baumann <mail@andreasbaumann.cc> | 2015-01-03 12:04:58 +0100 |
commit | 008d0be72b2f160382c6e880765e96b64a050c65 (patch) | |
tree | 36f48a98a3815a408e2ce1693dd182af90f80305 /release/src/linux/linux/net/ipv4/netfilter/ipt_tcpmss.c | |
parent | 611becfb8726c60cb060368541ad98191d4532f5 (diff) | |
download | tomato-008d0be72b2f160382c6e880765e96b64a050c65.tar.gz tomato-008d0be72b2f160382c6e880765e96b64a050c65.tar.bz2 |
imported original firmware WRT54GL_v4.30.11_11_US
Diffstat (limited to 'release/src/linux/linux/net/ipv4/netfilter/ipt_tcpmss.c')
-rw-r--r-- | release/src/linux/linux/net/ipv4/netfilter/ipt_tcpmss.c | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/release/src/linux/linux/net/ipv4/netfilter/ipt_tcpmss.c b/release/src/linux/linux/net/ipv4/netfilter/ipt_tcpmss.c new file mode 100644 index 00000000..001f7a83 --- /dev/null +++ b/release/src/linux/linux/net/ipv4/netfilter/ipt_tcpmss.c @@ -0,0 +1,109 @@ +/* Kernel module to match TCP MSS values. */ +#include <linux/module.h> +#include <linux/skbuff.h> +#include <net/tcp.h> + +#include <linux/netfilter_ipv4/ipt_tcpmss.h> +#include <linux/netfilter_ipv4/ip_tables.h> + +#define TH_SYN 0x02 + +/* Returns 1 if the mss option is set and matched by the range, 0 otherwise */ +static inline int +mssoption_match(u_int16_t min, u_int16_t max, + const struct tcphdr *tcp, + u_int16_t datalen, + int invert, + int *hotdrop) +{ + unsigned int i; + const u_int8_t *opt = (u_int8_t *)tcp; + + /* If we don't have the whole header, drop packet. */ + if (tcp->doff * 4 > datalen) { + *hotdrop = 1; + return 0; + } + + for (i = sizeof(struct tcphdr); i < tcp->doff * 4; ) { + if ((opt[i] == TCPOPT_MSS) + && ((tcp->doff * 4 - i) >= TCPOLEN_MSS) + && (opt[i+1] == TCPOLEN_MSS)) { + u_int16_t mssval; + + mssval = (opt[i+2] << 8) | opt[i+3]; + + return (mssval >= min && mssval <= max) ^ invert; + } + if (opt[i] < 2) i++; + else i += opt[i+1]?:1; + } + + return invert; +} + +static int +match(const struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + const void *matchinfo, + int offset, + const void *hdr, + u_int16_t datalen, + int *hotdrop) +{ + const struct ipt_tcpmss_match_info *info = matchinfo; + const struct tcphdr *tcph = (void *)skb->nh.iph + skb->nh.iph->ihl*4; + + return mssoption_match(info->mss_min, info->mss_max, tcph, + skb->len - skb->nh.iph->ihl*4, + info->invert, hotdrop); +} + +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)) + return 1; + + return 0; +} + +static int +checkentry(const char *tablename, + const struct ipt_ip *ip, + void *matchinfo, + unsigned int matchsize, + unsigned int hook_mask) +{ + if (matchsize != IPT_ALIGN(sizeof(struct ipt_tcpmss_match_info))) + return 0; + + /* Must specify -p tcp */ + if (ip->proto != IPPROTO_TCP || (ip->invflags & IPT_INV_PROTO)) { + printk("tcpmss: Only works on TCP packets\n"); + return 0; + } + + return 1; +} + +static struct ipt_match tcpmss_match += { { NULL, NULL }, "tcpmss", &match, &checkentry, NULL, THIS_MODULE }; + +static int __init init(void) +{ + return ipt_register_match(&tcpmss_match); +} + +static void __exit fini(void) +{ + ipt_unregister_match(&tcpmss_match); +} + +module_init(init); +module_exit(fini); +MODULE_LICENSE("GPL"); |