netfilter: nft_osf: Add ttl option support

Add ttl option support to the nftables "osf" expression.

Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/linux/netfilter/nfnetlink_osf.h b/include/linux/netfilter/nfnetlink_osf.h
index ecf7dab..c600004 100644 (file)
--- a/include/linux/netfilter/nfnetlink_osf.h
+++ b/include/linux/netfilter/nfnetlink_osf.h
@@ -27,6 +27,7 @@ bool nf_osf_match(const struct sk_buff *skb, u_int8_t family,
                  const struct list_head *nf_osf_fingers);
 
 const char *nf_osf_find(const struct sk_buff *skb,
-                        const struct list_head *nf_osf_fingers);
+                       const struct list_head *nf_osf_fingers,
+                       const int ttl_check);
 
 #endif /* _NFOSF_H */

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 5444e76..579974b 100644 (file)
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -1511,9 +1511,16 @@ enum nft_flowtable_hook_attributes {
 };
 #define NFTA_FLOWTABLE_HOOK_MAX        (__NFTA_FLOWTABLE_HOOK_MAX - 1)
 
+/**
+ * enum nft_osf_attributes - nftables osf expression netlink attributes
+ *
+ * @NFTA_OSF_DREG: destination register (NLA_U32: nft_registers)
+ * @NFTA_OSF_TTL: Value of the TTL osf option (NLA_U8)
+ */
 enum nft_osf_attributes {
        NFTA_OSF_UNSPEC,
        NFTA_OSF_DREG,
+       NFTA_OSF_TTL,
        __NFTA_OSF_MAX,
 };
 #define NFTA_OSF_MAX (__NFTA_OSF_MAX - 1)

diff --git a/net/netfilter/nfnetlink_osf.c b/net/netfilter/nfnetlink_osf.c
index 00db27d..6f41dd7 100644 (file)
--- a/net/netfilter/nfnetlink_osf.c
+++ b/net/netfilter/nfnetlink_osf.c
@@ -30,32 +30,27 @@ EXPORT_SYMBOL_GPL(nf_osf_fingers);
 static inline int nf_osf_ttl(const struct sk_buff *skb,
                             int ttl_check, unsigned char f_ttl)
 {
+       struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
        const struct iphdr *ip = ip_hdr(skb);
-
-       if (ttl_check != -1) {
-               if (ttl_check == NF_OSF_TTL_TRUE)
-                       return ip->ttl == f_ttl;
-               if (ttl_check == NF_OSF_TTL_NOCHECK)
-                       return 1;
-               else if (ip->ttl <= f_ttl)
-                       return 1;
-               else {
-                       struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
-                       int ret = 0;
-
-                       for_ifa(in_dev) {
-                               if (inet_ifa_match(ip->saddr, ifa)) {
-                                       ret = (ip->ttl == f_ttl);
-                                       break;
-                               }
-                       }
-                       endfor_ifa(in_dev);
-
-                       return ret;
+       int ret = 0;
+
+       if (ttl_check == NF_OSF_TTL_TRUE)
+               return ip->ttl == f_ttl;
+       if (ttl_check == NF_OSF_TTL_NOCHECK)
+               return 1;
+       else if (ip->ttl <= f_ttl)
+               return 1;
+
+       for_ifa(in_dev) {
+               if (inet_ifa_match(ip->saddr, ifa)) {
+                       ret = (ip->ttl == f_ttl);
+                       break;
                }
        }
 
-       return ip->ttl == f_ttl;
+       endfor_ifa(in_dev);
+
+       return ret;
 }
 
 struct nf_osf_hdr_ctx {
@@ -213,7 +208,7 @@ nf_osf_match(const struct sk_buff *skb, u_int8_t family,
        if (!tcp)
                return false;
 
-       ttl_check = (info->flags & NF_OSF_TTL) ? info->ttl : -1;
+       ttl_check = (info->flags & NF_OSF_TTL) ? info->ttl : 0;
 
        list_for_each_entry_rcu(kf, &nf_osf_fingers[ctx.df], finger_entry) {
 
@@ -257,7 +252,8 @@ nf_osf_match(const struct sk_buff *skb, u_int8_t family,
 EXPORT_SYMBOL_GPL(nf_osf_match);
 
 const char *nf_osf_find(const struct sk_buff *skb,
-                       const struct list_head *nf_osf_fingers)
+                       const struct list_head *nf_osf_fingers,
+                       const int ttl_check)
 {
        const struct iphdr *ip = ip_hdr(skb);
        const struct nf_osf_user_finger *f;
@@ -275,7 +271,7 @@ const char *nf_osf_find(const struct sk_buff *skb,
 
        list_for_each_entry_rcu(kf, &nf_osf_fingers[ctx.df], finger_entry) {
                f = &kf->finger;
-               if (!nf_osf_match_one(skb, f, -1, &ctx))
+               if (!nf_osf_match_one(skb, f, ttl_check, &ctx))
                        continue;
 
                genre = f->genre;

diff --git a/net/netfilter/nft_osf.c b/net/netfilter/nft_osf.c
index a35fb59..0b452fd 100644 (file)
--- a/net/netfilter/nft_osf.c
+++ b/net/netfilter/nft_osf.c
@@ -6,10 +6,12 @@
 
 struct nft_osf {
        enum nft_registers      dreg:8;
+       u8                      ttl;
 };
 
 static const struct nla_policy nft_osf_policy[NFTA_OSF_MAX + 1] = {
        [NFTA_OSF_DREG]         = { .type = NLA_U32 },
+       [NFTA_OSF_TTL]          = { .type = NLA_U8 },
 };
 
 static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
@@ -33,7 +35,7 @@ static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
                return;
        }
 
-       os_name = nf_osf_find(skb, nf_osf_fingers);
+       os_name = nf_osf_find(skb, nf_osf_fingers, priv->ttl);
        if (!os_name)
                strncpy((char *)dest, "unknown", NFT_OSF_MAXGENRELEN);
        else
@@ -46,6 +48,14 @@ static int nft_osf_init(const struct nft_ctx *ctx,
 {
        struct nft_osf *priv = nft_expr_priv(expr);
        int err;
+       u8 ttl;
+
+       if (nla_get_u8(tb[NFTA_OSF_TTL])) {
+               ttl = nla_get_u8(tb[NFTA_OSF_TTL]);
+               if (ttl > 2)
+                       return -EINVAL;
+               priv->ttl = ttl;
+       }
 
        priv->dreg = nft_parse_register(tb[NFTA_OSF_DREG]);
        err = nft_validate_register_store(ctx, priv->dreg, NULL,
@@ -60,6 +70,9 @@ static int nft_osf_dump(struct sk_buff *skb, const struct nft_expr *expr)
 {
        const struct nft_osf *priv = nft_expr_priv(expr);
 
+       if (nla_put_u8(skb, NFTA_OSF_TTL, priv->ttl))
+               goto nla_put_failure;
+
        if (nft_dump_register(skb, NFTA_OSF_DREG, priv->dreg))
                goto nla_put_failure;