Commonly, ethernet addresses are just using a policy of
{ .len = ETH_ALEN }
which leaves userspace free to send more data than it should,
which may hide bugs.
Introduce NLA_EXACT_LEN which checks for exact size, rejecting
the attribute if it's not exactly that length. Also add
NLA_EXACT_LEN_WARN which requires the minimum length and will
warn on longer attributes, for backward compatibility.
Use these to define NLA_POLICY_ETH_ADDR (new strict policy) and
NLA_POLICY_ETH_ADDR_COMPAT (compatible policy with warning);
these are used like this:
static const struct nla_policy <name>[...] = {
[NL_ATTR_NAME] = NLA_POLICY_ETH_ADDR,
...
};
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
NLA_S64,
NLA_BITFIELD32,
NLA_REJECT,
+ NLA_EXACT_LEN,
+ NLA_EXACT_LEN_WARN,
__NLA_TYPE_MAX,
};
* just like "All other"
* NLA_BITFIELD32 Unused
* NLA_REJECT Unused
+ * NLA_EXACT_LEN Attribute must have exactly this length, otherwise
+ * it is rejected.
+ * NLA_EXACT_LEN_WARN Attribute should have exactly this length, a warning
+ * is logged if it is longer, shorter is rejected.
* All other Minimum length of attribute payload
*
* Meaning of `validation_data' field:
void *validation_data;
};
+#define NLA_POLICY_EXACT_LEN(_len) { .type = NLA_EXACT_LEN, .len = _len }
+#define NLA_POLICY_EXACT_LEN_WARN(_len) { .type = NLA_EXACT_LEN_WARN, \
+ .len = _len }
+
+#define NLA_POLICY_ETH_ADDR NLA_POLICY_EXACT_LEN(ETH_ALEN)
+#define NLA_POLICY_ETH_ADDR_COMPAT NLA_POLICY_EXACT_LEN_WARN(ETH_ALEN)
+
/**
* struct nl_info - netlink source information
* @nlh: Netlink message header of original request
BUG_ON(pt->type > NLA_TYPE_MAX);
- if (nla_attr_len[pt->type] && attrlen != nla_attr_len[pt->type]) {
+ if ((nla_attr_len[pt->type] && attrlen != nla_attr_len[pt->type]) ||
+ (pt->type == NLA_EXACT_LEN_WARN && attrlen != pt->len)) {
pr_warn_ratelimited("netlink: '%s': attribute type %d has an invalid length.\n",
current->comm, type);
}
switch (pt->type) {
+ case NLA_EXACT_LEN:
+ if (attrlen != pt->len)
+ return -ERANGE;
+ break;
+
case NLA_REJECT:
if (pt->validation_data && error_msg)
*error_msg = pt->validation_data;