Add ttl option support to the nftables "osf" expression.
Signed-off-by: Fernando Fernandez Mancera <ffmanc...@riseup.net>
---
v1:initial patch
v2:v2: code correctness and fix the "~" typo.
v3:make priv->ttl = ttl; optional and priv->ttl default value is now 0.
v4:delete "if (ttl_check != -1)" branch
---
include/linux/netfilter/nfnetlink_osf.h | 3 +-
include/uapi/linux/netfilter/nf_tables.h | 7 ++++
net/netfilter/nfnetlink_osf.c | 46 +++++++++++-------------
net/netfilter/nft_osf.c | 15 +++++++-
4 files changed, 44 insertions(+), 27 deletions(-)
diff --git a/include/linux/netfilter/nfnetlink_osf.h
b/include/linux/netfilter/nfnetlink_osf.h
index ecf7dab81e9e..c6000046c966 100644
--- 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 5444e76870bb..579974b0bf0d 100644
--- 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 00db27dfd2ff..6f41dd74729d 100644
--- 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 bce6617ca514..fe689ba6367a 100644
--- 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;
--
2.19.1
