[PATCH 5.15 338/570] netlink: introduce NLA_POLICY_MAX_BE

Greg Kroah-Hartman
2026-04-13T16:34:03Z

From: Florian Westphal <fw@strlen.de>

[ Upstream commit 08724ef69907214ce622344fe4945412e38368f0 ]

netlink allows to specify allowed ranges for integer types.
Unfortunately, nfnetlink passes integers in big endian, so the existing
NLA_POLICY_MAX() cannot be used.

At the moment, nfnetlink users, such as nf_tables, need to resort to
programmatic checking via helpers such as nft_parse_u32_check().

This is both cumbersome and error prone. This adds NLA_POLICY_MAX_BE
which adds range check support for BE16, BE32 and BE64 integers.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 8f15b5071b45 ("netfilter: ctnetlink: use netlink policy range checks")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/netlink.h | 9 +++++++++
lib/nlattr.c | 31 +++++++++++++++++++++++++++----
2 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/include/net/netlink.h b/include/net/netlink.h
index 7a2a9d3144ba6..6eb4593983319 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -325,6 +325,7 @@ struct nla_policy {
struct netlink_range_validation_signed *range_signed;
struct {
s16 min, max;
+ u8 network_byte_order:1;
};
int (*validate)(const struct nlattr *attr,
struct netlink_ext_ack *extack);
@@ -418,6 +419,14 @@ struct nla_policy {
.type = NLA_ENSURE_INT_OR_BINARY_TYPE(tp), \
.validation_type = NLA_VALIDATE_MAX, \
.max = _max, \
+ .network_byte_order = 0, \
+}
+
+#define NLA_POLICY_MAX_BE(tp, _max) { \
+ .type = NLA_ENSURE_UINT_TYPE(tp), \
+ .validation_type = NLA_VALIDATE_MAX, \
+ .max = _max, \
+ .network_byte_order = 1, \
}

#define NLA_POLICY_MASK(tp, _mask) { \
diff --git a/lib/nlattr.c b/lib/nlattr.c
index 73635bdb00620..a0c80fbf71895 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -160,6 +160,31 @@ void nla_get_range_unsigned(const struct nla_policy *pt,
}
}

+static u64 nla_get_attr_bo(const struct nla_policy *pt,
+ const struct nlattr *nla)
+{
+ switch (pt->type) {
+ case NLA_U16:
+ if (pt->network_byte_order)
+ return ntohs(nla_get_be16(nla));
+
+ return nla_get_u16(nla);
+ case NLA_U32:
+ if (pt->network_byte_order)
+ return ntohl(nla_get_be32(nla));
+
+ return nla_get_u32(nla);
+ case NLA_U64:
+ if (pt->network_byte_order)
+ return be64_to_cpu(nla_get_be64(nla));
+
+ return nla_get_u64(nla);
+ }
+
+ WARN_ON_ONCE(1);
+ return 0;
+}
+
static int nla_validate_range_unsigned(const struct nla_policy *pt,
const struct nlattr *nla,
struct netlink_ext_ack *extack,
@@ -173,12 +198,10 @@ static int nla_validate_range_unsigned(const struct nla_policy *pt,
value = nla_get_u8(nla);
break;
case NLA_U16:
- value = nla_get_u16(nla);
- break;
case NLA_U32:
- value = nla_get_u32(nla);
- break;
case NLA_U64:
+ value = nla_get_attr_bo(pt, nla);
+ break;
case NLA_MSECS:
value = nla_get_u64(nla);
break;
--
2.51.0