[PATCH net-next v3 1/4] netfilter: conntrack: add shared port and uint parsers for helpers

[HACKE-RC <rc@rexion.ai>]

Add nf_ct_helper_parse_uint() for bounded unsigned integer parsing
from an unterminated buffer, and nf_ct_helper_parse_port() which calls
it with max=65535 and rejects port zero.  Both helpers are exported so
conntrack protocol helpers can replace ad-hoc simple_strtoul() usage.

Signed-off-by: HACKE-RC <rc@rexion.ai>
---
 include/net/netfilter/nf_conntrack_helper.h |  5 +++
 net/netfilter/nf_conntrack_helper.c         | 39 +++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h
index de2f956ab..ab145fcd9 100644
--- a/include/net/netfilter/nf_conntrack_helper.h
+++ b/include/net/netfilter/nf_conntrack_helper.h
@@ -160,6 +160,11 @@ nf_ct_helper_expectfn_find_by_name(const char *name);
 struct nf_ct_helper_expectfn *
 nf_ct_helper_expectfn_find_by_symbol(const void *symbol);
 
+int nf_ct_helper_parse_uint(const char *cp, unsigned int len,
+			    unsigned long max, unsigned long *val, char **endp);
+int nf_ct_helper_parse_port(const char *cp, unsigned int len,
+			    u16 *port, char **endp);
+
 extern struct hlist_head *nf_ct_helper_hash;
 extern unsigned int nf_ct_helper_hsize;
 
diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index a715304a5..f6229957c 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -499,6 +499,45 @@ void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat)
 }
 EXPORT_SYMBOL_GPL(nf_nat_helper_unregister);
 
+int nf_ct_helper_parse_uint(const char *cp, unsigned int len,
+			    unsigned long max, unsigned long *val, char **endp)
+{
+	unsigned long result = 0;
+
+	if (!len || *cp < '0' || *cp > '9')
+		return -1;
+
+	while (len > 0 && *cp >= '0' && *cp <= '9') {
+		result = result * 10 + (*cp - '0');
+		if (result > max)
+			return -1;
+		cp++;
+		len--;
+	}
+
+	*val = result;
+	if (endp)
+		*endp = (char *)cp;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nf_ct_helper_parse_uint);
+
+int nf_ct_helper_parse_port(const char *cp, unsigned int len,
+			    u16 *port, char **endp)
+{
+	unsigned long val;
+
+	if (nf_ct_helper_parse_uint(cp, len, 65535, &val, endp))
+		return -1;
+	if (val == 0)
+		return -1;
+
+	*port = val;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nf_ct_helper_parse_port);
+
 int nf_conntrack_helper_init(void)
 {
 	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
-- 
2.54.0