netfilter: ipset: Replace strlcpy with strscpy

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().

Direct replacement is safe here since return value from all
callers of STRLCPY macro were ignored.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Acked-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230613003437.3538694-1-azeemshaikh38@gmail.com

net/netfilter/ipset/ip_set_hash_netiface.c

@@ -40,7 +40,7 @@ MODULE_ALIAS("ip_set_hash:net,iface");
 #define IP_SET_HASH_WITH_MULTI
 #define IP_SET_HASH_WITH_NET0
 
-#define STRLCPY(a, b)	strlcpy(a, b, IFNAMSIZ)
+#define STRSCPY(a, b)	strscpy(a, b, IFNAMSIZ)
 
 /* IPv4 variant */
 
@@ -182,11 +182,11 @@ hash_netiface4_kadt(struct ip_set *set, const struct sk_buff *skb,
 
 		if (!eiface)
 			return -EINVAL;
-		STRLCPY(e.iface, eiface);
+		STRSCPY(e.iface, eiface);
 		e.physdev = 1;
 #endif
 	} else {
-		STRLCPY(e.iface, SRCDIR ? IFACE(in) : IFACE(out));
+		STRSCPY(e.iface, SRCDIR ? IFACE(in) : IFACE(out));
 	}
 
 	if (strlen(e.iface) == 0)
@@ -400,11 +400,11 @@ hash_netiface6_kadt(struct ip_set *set, const struct sk_buff *skb,
 
 		if (!eiface)
 			return -EINVAL;
-		STRLCPY(e.iface, eiface);
+		STRSCPY(e.iface, eiface);
 		e.physdev = 1;
 #endif
 	} else {
-		STRLCPY(e.iface, SRCDIR ? IFACE(in) : IFACE(out));
+		STRSCPY(e.iface, SRCDIR ? IFACE(in) : IFACE(out));
 	}
 
 	if (strlen(e.iface) == 0)