mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-06 19:07:52 +00:00
netfilter: nf_osf: add struct nf_osf_hdr_ctx
Wrap context that allow us to guess the OS into a structure. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
parent
06ff4aa252
commit
31a9c29210
1 changed files with 62 additions and 43 deletions
|
@ -51,18 +51,25 @@ static inline int nf_osf_ttl(const struct sk_buff *skb,
|
||||||
return ip->ttl == f_ttl;
|
return ip->ttl == f_ttl;
|
||||||
}
|
}
|
||||||
|
|
||||||
|
struct nf_osf_hdr_ctx {
|
||||||
|
bool df;
|
||||||
|
u16 window;
|
||||||
|
u16 totlen;
|
||||||
|
const unsigned char *optp;
|
||||||
|
unsigned int optsize;
|
||||||
|
};
|
||||||
|
|
||||||
static bool nf_osf_match_one(const struct sk_buff *skb,
|
static bool nf_osf_match_one(const struct sk_buff *skb,
|
||||||
const struct nf_osf_user_finger *f,
|
const struct nf_osf_user_finger *f,
|
||||||
int ttl_check, u16 totlen, u16 window,
|
int ttl_check,
|
||||||
const unsigned char *optp,
|
struct nf_osf_hdr_ctx *ctx)
|
||||||
unsigned int optsize)
|
|
||||||
{
|
{
|
||||||
unsigned int check_WSS = 0;
|
unsigned int check_WSS = 0;
|
||||||
int fmatch = FMATCH_WRONG;
|
int fmatch = FMATCH_WRONG;
|
||||||
int foptsize, optnum;
|
int foptsize, optnum;
|
||||||
u16 mss = 0;
|
u16 mss = 0;
|
||||||
|
|
||||||
if (totlen != f->ss || !nf_osf_ttl(skb, ttl_check, f->ttl))
|
if (ctx->totlen != f->ss || !nf_osf_ttl(skb, ttl_check, f->ttl))
|
||||||
return false;
|
return false;
|
||||||
|
|
||||||
/*
|
/*
|
||||||
|
@ -78,24 +85,24 @@ static bool nf_osf_match_one(const struct sk_buff *skb,
|
||||||
foptsize += f->opt[optnum].length;
|
foptsize += f->opt[optnum].length;
|
||||||
|
|
||||||
if (foptsize > MAX_IPOPTLEN ||
|
if (foptsize > MAX_IPOPTLEN ||
|
||||||
optsize > MAX_IPOPTLEN ||
|
ctx->optsize > MAX_IPOPTLEN ||
|
||||||
optsize != foptsize)
|
ctx->optsize != foptsize)
|
||||||
return false;
|
return false;
|
||||||
|
|
||||||
check_WSS = f->wss.wc;
|
check_WSS = f->wss.wc;
|
||||||
|
|
||||||
for (optnum = 0; optnum < f->opt_num; ++optnum) {
|
for (optnum = 0; optnum < f->opt_num; ++optnum) {
|
||||||
if (f->opt[optnum].kind == (*optp)) {
|
if (f->opt[optnum].kind == *ctx->optp) {
|
||||||
__u32 len = f->opt[optnum].length;
|
__u32 len = f->opt[optnum].length;
|
||||||
const __u8 *optend = optp + len;
|
const __u8 *optend = ctx->optp + len;
|
||||||
|
|
||||||
fmatch = FMATCH_OK;
|
fmatch = FMATCH_OK;
|
||||||
|
|
||||||
switch (*optp) {
|
switch (*ctx->optp) {
|
||||||
case OSFOPT_MSS:
|
case OSFOPT_MSS:
|
||||||
mss = optp[3];
|
mss = ctx->optp[3];
|
||||||
mss <<= 8;
|
mss <<= 8;
|
||||||
mss |= optp[2];
|
mss |= ctx->optp[2];
|
||||||
|
|
||||||
mss = ntohs((__force __be16)mss);
|
mss = ntohs((__force __be16)mss);
|
||||||
break;
|
break;
|
||||||
|
@ -103,7 +110,7 @@ static bool nf_osf_match_one(const struct sk_buff *skb,
|
||||||
break;
|
break;
|
||||||
}
|
}
|
||||||
|
|
||||||
optp = optend;
|
ctx->optp = optend;
|
||||||
} else
|
} else
|
||||||
fmatch = FMATCH_OPT_WRONG;
|
fmatch = FMATCH_OPT_WRONG;
|
||||||
|
|
||||||
|
@ -116,7 +123,7 @@ static bool nf_osf_match_one(const struct sk_buff *skb,
|
||||||
|
|
||||||
switch (check_WSS) {
|
switch (check_WSS) {
|
||||||
case OSF_WSS_PLAIN:
|
case OSF_WSS_PLAIN:
|
||||||
if (f->wss.val == 0 || window == f->wss.val)
|
if (f->wss.val == 0 || ctx->window == f->wss.val)
|
||||||
fmatch = FMATCH_OK;
|
fmatch = FMATCH_OK;
|
||||||
break;
|
break;
|
||||||
case OSF_WSS_MSS:
|
case OSF_WSS_MSS:
|
||||||
|
@ -128,19 +135,19 @@ static bool nf_osf_match_one(const struct sk_buff *skb,
|
||||||
*/
|
*/
|
||||||
#define SMART_MSS_1 1460
|
#define SMART_MSS_1 1460
|
||||||
#define SMART_MSS_2 1448
|
#define SMART_MSS_2 1448
|
||||||
if (window == f->wss.val * mss ||
|
if (ctx->window == f->wss.val * mss ||
|
||||||
window == f->wss.val * SMART_MSS_1 ||
|
ctx->window == f->wss.val * SMART_MSS_1 ||
|
||||||
window == f->wss.val * SMART_MSS_2)
|
ctx->window == f->wss.val * SMART_MSS_2)
|
||||||
fmatch = FMATCH_OK;
|
fmatch = FMATCH_OK;
|
||||||
break;
|
break;
|
||||||
case OSF_WSS_MTU:
|
case OSF_WSS_MTU:
|
||||||
if (window == f->wss.val * (mss + 40) ||
|
if (ctx->window == f->wss.val * (mss + 40) ||
|
||||||
window == f->wss.val * (SMART_MSS_1 + 40) ||
|
ctx->window == f->wss.val * (SMART_MSS_1 + 40) ||
|
||||||
window == f->wss.val * (SMART_MSS_2 + 40))
|
ctx->window == f->wss.val * (SMART_MSS_2 + 40))
|
||||||
fmatch = FMATCH_OK;
|
fmatch = FMATCH_OK;
|
||||||
break;
|
break;
|
||||||
case OSF_WSS_MODULO:
|
case OSF_WSS_MODULO:
|
||||||
if ((window % f->wss.val) == 0)
|
if ((ctx->window % f->wss.val) == 0)
|
||||||
fmatch = FMATCH_OK;
|
fmatch = FMATCH_OK;
|
||||||
break;
|
break;
|
||||||
}
|
}
|
||||||
|
@ -149,54 +156,66 @@ static bool nf_osf_match_one(const struct sk_buff *skb,
|
||||||
return fmatch == FMATCH_OK;
|
return fmatch == FMATCH_OK;
|
||||||
}
|
}
|
||||||
|
|
||||||
|
static const struct tcphdr *nf_osf_hdr_ctx_init(struct nf_osf_hdr_ctx *ctx,
|
||||||
|
const struct sk_buff *skb,
|
||||||
|
const struct iphdr *ip,
|
||||||
|
unsigned char *opts)
|
||||||
|
{
|
||||||
|
const struct tcphdr *tcp;
|
||||||
|
struct tcphdr _tcph;
|
||||||
|
|
||||||
|
tcp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(struct tcphdr), &_tcph);
|
||||||
|
if (!tcp)
|
||||||
|
return NULL;
|
||||||
|
|
||||||
|
if (!tcp->syn)
|
||||||
|
return NULL;
|
||||||
|
|
||||||
|
ctx->totlen = ntohs(ip->tot_len);
|
||||||
|
ctx->df = ntohs(ip->frag_off) & IP_DF;
|
||||||
|
ctx->window = ntohs(tcp->window);
|
||||||
|
|
||||||
|
if (tcp->doff * 4 > sizeof(struct tcphdr)) {
|
||||||
|
ctx->optsize = tcp->doff * 4 - sizeof(struct tcphdr);
|
||||||
|
|
||||||
|
ctx->optp = skb_header_pointer(skb, ip_hdrlen(skb) +
|
||||||
|
sizeof(struct tcphdr), ctx->optsize, opts);
|
||||||
|
}
|
||||||
|
|
||||||
|
return tcp;
|
||||||
|
}
|
||||||
|
|
||||||
bool
|
bool
|
||||||
nf_osf_match(const struct sk_buff *skb, u_int8_t family,
|
nf_osf_match(const struct sk_buff *skb, u_int8_t family,
|
||||||
int hooknum, struct net_device *in, struct net_device *out,
|
int hooknum, struct net_device *in, struct net_device *out,
|
||||||
const struct nf_osf_info *info, struct net *net,
|
const struct nf_osf_info *info, struct net *net,
|
||||||
const struct list_head *nf_osf_fingers)
|
const struct list_head *nf_osf_fingers)
|
||||||
{
|
{
|
||||||
const unsigned char *optp = NULL, *_optp = NULL;
|
|
||||||
const struct iphdr *ip = ip_hdr(skb);
|
const struct iphdr *ip = ip_hdr(skb);
|
||||||
const struct nf_osf_user_finger *f;
|
const struct nf_osf_user_finger *f;
|
||||||
unsigned char opts[MAX_IPOPTLEN];
|
unsigned char opts[MAX_IPOPTLEN];
|
||||||
const struct nf_osf_finger *kf;
|
const struct nf_osf_finger *kf;
|
||||||
int fcount = 0, ttl_check;
|
int fcount = 0, ttl_check;
|
||||||
int fmatch = FMATCH_WRONG;
|
int fmatch = FMATCH_WRONG;
|
||||||
unsigned int optsize = 0;
|
struct nf_osf_hdr_ctx ctx;
|
||||||
const struct tcphdr *tcp;
|
const struct tcphdr *tcp;
|
||||||
struct tcphdr _tcph;
|
|
||||||
u16 window, totlen;
|
|
||||||
bool df;
|
|
||||||
|
|
||||||
tcp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(struct tcphdr), &_tcph);
|
memset(&ctx, 0, sizeof(ctx));
|
||||||
|
|
||||||
|
tcp = nf_osf_hdr_ctx_init(&ctx, skb, ip, opts);
|
||||||
if (!tcp)
|
if (!tcp)
|
||||||
return false;
|
return false;
|
||||||
|
|
||||||
if (!tcp->syn)
|
|
||||||
return false;
|
|
||||||
|
|
||||||
totlen = ntohs(ip->tot_len);
|
|
||||||
df = ntohs(ip->frag_off) & IP_DF;
|
|
||||||
window = ntohs(tcp->window);
|
|
||||||
|
|
||||||
if (tcp->doff * 4 > sizeof(struct tcphdr)) {
|
|
||||||
optsize = tcp->doff * 4 - sizeof(struct tcphdr);
|
|
||||||
|
|
||||||
_optp = optp = skb_header_pointer(skb, ip_hdrlen(skb) +
|
|
||||||
sizeof(struct tcphdr), optsize, opts);
|
|
||||||
}
|
|
||||||
|
|
||||||
ttl_check = (info->flags & NF_OSF_TTL) ? info->ttl : -1;
|
ttl_check = (info->flags & NF_OSF_TTL) ? info->ttl : -1;
|
||||||
|
|
||||||
list_for_each_entry_rcu(kf, &nf_osf_fingers[df], finger_entry) {
|
list_for_each_entry_rcu(kf, &nf_osf_fingers[ctx.df], finger_entry) {
|
||||||
|
|
||||||
f = &kf->finger;
|
f = &kf->finger;
|
||||||
|
|
||||||
if (!(info->flags & NF_OSF_LOG) && strcmp(info->genre, f->genre))
|
if (!(info->flags & NF_OSF_LOG) && strcmp(info->genre, f->genre))
|
||||||
continue;
|
continue;
|
||||||
|
|
||||||
if (!nf_osf_match_one(skb, f,
|
if (!nf_osf_match_one(skb, f, ttl_check, &ctx))
|
||||||
ttl_check, totlen, window, optp, optsize))
|
|
||||||
continue;
|
continue;
|
||||||
|
|
||||||
fmatch = FMATCH_OK;
|
fmatch = FMATCH_OK;
|
||||||
|
|
Loading…
Reference in a new issue