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Diffstat (limited to 'net/netfilter/nf_osf.c')
-rw-r--r--net/netfilter/nf_osf.c252
1 files changed, 143 insertions, 109 deletions
diff --git a/net/netfilter/nf_osf.c b/net/netfilter/nf_osf.c
index 5ba5c7bef2f9..b44d62d5d9a9 100644
--- a/net/netfilter/nf_osf.c
+++ b/net/netfilter/nf_osf.c
@@ -21,15 +21,14 @@
#include <linux/netfilter/nf_osf.h>
static inline int nf_osf_ttl(const struct sk_buff *skb,
- const struct nf_osf_info *info,
- unsigned char f_ttl)
+ int ttl_check, unsigned char f_ttl)
{
const struct iphdr *ip = ip_hdr(skb);
- if (info->flags & NF_OSF_TTL) {
- if (info->ttl == NF_OSF_TTL_TRUE)
+ if (ttl_check != -1) {
+ if (ttl_check == NF_OSF_TTL_TRUE)
return ip->ttl == f_ttl;
- if (info->ttl == NF_OSF_TTL_NOCHECK)
+ if (ttl_check == NF_OSF_TTL_NOCHECK)
return 1;
else if (ip->ttl <= f_ttl)
return 1;
@@ -52,140 +51,175 @@ static inline int nf_osf_ttl(const struct sk_buff *skb,
return ip->ttl == f_ttl;
}
-bool
-nf_osf_match(const struct sk_buff *skb, u_int8_t family,
- int hooknum, struct net_device *in, struct net_device *out,
- const struct nf_osf_info *info, struct net *net,
- const struct list_head *nf_osf_fingers)
+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,
+ const struct nf_osf_user_finger *f,
+ int ttl_check,
+ struct nf_osf_hdr_ctx *ctx)
{
- const unsigned char *optp = NULL, *_optp = NULL;
- unsigned int optsize = 0, check_WSS = 0;
- int fmatch = FMATCH_WRONG, fcount = 0;
- const struct iphdr *ip = ip_hdr(skb);
- const struct nf_osf_user_finger *f;
- unsigned char opts[MAX_IPOPTLEN];
- const struct nf_osf_finger *kf;
- u16 window, totlen, mss = 0;
- const struct tcphdr *tcp;
- struct tcphdr _tcph;
- bool df;
+ unsigned int check_WSS = 0;
+ int fmatch = FMATCH_WRONG;
+ int foptsize, optnum;
+ u16 mss = 0;
- tcp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(struct tcphdr), &_tcph);
- if (!tcp)
+ if (ctx->totlen != f->ss || !nf_osf_ttl(skb, ttl_check, f->ttl))
return false;
- if (!tcp->syn)
+ /*
+ * Should not happen if userspace parser was written correctly.
+ */
+ if (f->wss.wc >= OSF_WSS_MAX)
return false;
- totlen = ntohs(ip->tot_len);
- df = ntohs(ip->frag_off) & IP_DF;
- window = ntohs(tcp->window);
+ /* Check options */
- if (tcp->doff * 4 > sizeof(struct tcphdr)) {
- optsize = tcp->doff * 4 - sizeof(struct tcphdr);
+ foptsize = 0;
+ for (optnum = 0; optnum < f->opt_num; ++optnum)
+ foptsize += f->opt[optnum].length;
- _optp = optp = skb_header_pointer(skb, ip_hdrlen(skb) +
- sizeof(struct tcphdr), optsize, opts);
- }
+ if (foptsize > MAX_IPOPTLEN ||
+ ctx->optsize > MAX_IPOPTLEN ||
+ ctx->optsize != foptsize)
+ return false;
- list_for_each_entry_rcu(kf, &nf_osf_fingers[df], finger_entry) {
- int foptsize, optnum;
+ check_WSS = f->wss.wc;
- f = &kf->finger;
+ for (optnum = 0; optnum < f->opt_num; ++optnum) {
+ if (f->opt[optnum].kind == *ctx->optp) {
+ __u32 len = f->opt[optnum].length;
+ const __u8 *optend = ctx->optp + len;
- if (!(info->flags & NF_OSF_LOG) && strcmp(info->genre, f->genre))
- continue;
+ fmatch = FMATCH_OK;
+
+ switch (*ctx->optp) {
+ case OSFOPT_MSS:
+ mss = ctx->optp[3];
+ mss <<= 8;
+ mss |= ctx->optp[2];
+
+ mss = ntohs((__force __be16)mss);
+ break;
+ case OSFOPT_TS:
+ break;
+ }
+
+ ctx->optp = optend;
+ } else
+ fmatch = FMATCH_OPT_WRONG;
+
+ if (fmatch != FMATCH_OK)
+ break;
+ }
- optp = _optp;
+ if (fmatch != FMATCH_OPT_WRONG) {
fmatch = FMATCH_WRONG;
- if (totlen != f->ss || !nf_osf_ttl(skb, info, f->ttl))
- continue;
+ switch (check_WSS) {
+ case OSF_WSS_PLAIN:
+ if (f->wss.val == 0 || ctx->window == f->wss.val)
+ fmatch = FMATCH_OK;
+ break;
+ case OSF_WSS_MSS:
+ /*
+ * Some smart modems decrease mangle MSS to
+ * SMART_MSS_2, so we check standard, decreased
+ * and the one provided in the fingerprint MSS
+ * values.
+ */
+#define SMART_MSS_1 1460
+#define SMART_MSS_2 1448
+ if (ctx->window == f->wss.val * mss ||
+ ctx->window == f->wss.val * SMART_MSS_1 ||
+ ctx->window == f->wss.val * SMART_MSS_2)
+ fmatch = FMATCH_OK;
+ break;
+ case OSF_WSS_MTU:
+ if (ctx->window == f->wss.val * (mss + 40) ||
+ ctx->window == f->wss.val * (SMART_MSS_1 + 40) ||
+ ctx->window == f->wss.val * (SMART_MSS_2 + 40))
+ fmatch = FMATCH_OK;
+ break;
+ case OSF_WSS_MODULO:
+ if ((ctx->window % f->wss.val) == 0)
+ fmatch = FMATCH_OK;
+ break;
+ }
+ }
- /*
- * Should not happen if userspace parser was written correctly.
- */
- if (f->wss.wc >= OSF_WSS_MAX)
- continue;
+ return fmatch == FMATCH_OK;
+}
- /* Check options */
+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;
- foptsize = 0;
- for (optnum = 0; optnum < f->opt_num; ++optnum)
- foptsize += f->opt[optnum].length;
+ tcp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(struct tcphdr), &_tcph);
+ if (!tcp)
+ return NULL;
- if (foptsize > MAX_IPOPTLEN ||
- optsize > MAX_IPOPTLEN ||
- optsize != foptsize)
- continue;
+ if (!tcp->syn)
+ return NULL;
- check_WSS = f->wss.wc;
+ ctx->totlen = ntohs(ip->tot_len);
+ ctx->df = ntohs(ip->frag_off) & IP_DF;
+ ctx->window = ntohs(tcp->window);
- for (optnum = 0; optnum < f->opt_num; ++optnum) {
- if (f->opt[optnum].kind == (*optp)) {
- __u32 len = f->opt[optnum].length;
- const __u8 *optend = optp + len;
+ if (tcp->doff * 4 > sizeof(struct tcphdr)) {
+ ctx->optsize = tcp->doff * 4 - sizeof(struct tcphdr);
- fmatch = FMATCH_OK;
+ ctx->optp = skb_header_pointer(skb, ip_hdrlen(skb) +
+ sizeof(struct tcphdr), ctx->optsize, opts);
+ }
- switch (*optp) {
- case OSFOPT_MSS:
- mss = optp[3];
- mss <<= 8;
- mss |= optp[2];
+ return tcp;
+}
- mss = ntohs((__force __be16)mss);
- break;
- case OSFOPT_TS:
- break;
- }
+bool
+nf_osf_match(const struct sk_buff *skb, u_int8_t family,
+ int hooknum, struct net_device *in, struct net_device *out,
+ const struct nf_osf_info *info, struct net *net,
+ const struct list_head *nf_osf_fingers)
+{
+ const struct iphdr *ip = ip_hdr(skb);
+ const struct nf_osf_user_finger *f;
+ unsigned char opts[MAX_IPOPTLEN];
+ const struct nf_osf_finger *kf;
+ int fcount = 0, ttl_check;
+ int fmatch = FMATCH_WRONG;
+ struct nf_osf_hdr_ctx ctx;
+ const struct tcphdr *tcp;
- optp = optend;
- } else
- fmatch = FMATCH_OPT_WRONG;
+ memset(&ctx, 0, sizeof(ctx));
- if (fmatch != FMATCH_OK)
- break;
- }
+ tcp = nf_osf_hdr_ctx_init(&ctx, skb, ip, opts);
+ if (!tcp)
+ return false;
- if (fmatch != FMATCH_OPT_WRONG) {
- fmatch = FMATCH_WRONG;
+ ttl_check = (info->flags & NF_OSF_TTL) ? info->ttl : -1;
- switch (check_WSS) {
- case OSF_WSS_PLAIN:
- if (f->wss.val == 0 || window == f->wss.val)
- fmatch = FMATCH_OK;
- break;
- case OSF_WSS_MSS:
- /*
- * Some smart modems decrease mangle MSS to
- * SMART_MSS_2, so we check standard, decreased
- * and the one provided in the fingerprint MSS
- * values.
- */
-#define SMART_MSS_1 1460
-#define SMART_MSS_2 1448
- if (window == f->wss.val * mss ||
- window == f->wss.val * SMART_MSS_1 ||
- window == f->wss.val * SMART_MSS_2)
- fmatch = FMATCH_OK;
- break;
- case OSF_WSS_MTU:
- if (window == f->wss.val * (mss + 40) ||
- window == f->wss.val * (SMART_MSS_1 + 40) ||
- window == f->wss.val * (SMART_MSS_2 + 40))
- fmatch = FMATCH_OK;
- break;
- case OSF_WSS_MODULO:
- if ((window % f->wss.val) == 0)
- fmatch = FMATCH_OK;
- break;
- }
- }
+ list_for_each_entry_rcu(kf, &nf_osf_fingers[ctx.df], finger_entry) {
- if (fmatch != FMATCH_OK)
+ f = &kf->finger;
+
+ if (!(info->flags & NF_OSF_LOG) && strcmp(info->genre, f->genre))
+ continue;
+
+ if (!nf_osf_match_one(skb, f, ttl_check, &ctx))
continue;
+ fmatch = FMATCH_OK;
+
fcount++;
if (info->flags & NF_OSF_LOG)
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-14 21:34:07 +0000