[net v3] netlabel: validate unlabeled address and mask attribute lengths
From: Chenguang Zhao <hidden>
Date: 2026-06-03 01:14:25
Also in:
netdev
Subsystem:
networking [general], networking [labeled] (netlabel, labeled ipsec, secmark), the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Paul Moore, Linus Torvalds
netlbl_unlabel_addrinfo_get() used the address attribute length to
determine whether the attribute data could be read as an IPv4 or IPv6
address, but did not independently validate the corresponding mask
attribute length. A crafted Generic Netlink request could therefore
provide a valid IPv4/IPv6 address attribute with a shorter mask
attribute, which would later be read as a full struct in_addr or
struct in6_addr.
NLA_BINARY policy lengths are maximum lengths by default, so use
NLA_POLICY_EXACT_LEN() for the unlabeled IPv4/IPv6 address and mask
attributes. This rejects short attributes during policy validation and
also exposes the exact length requirements through policy introspection.
Fixes: 8cc44579d1bd ("NetLabel: Introduce static network labels for unlabeled connections")
Signed-off-by: Chenguang Zhao <redacted>
---
v3:
Use NLA_POLICY_EXACT_LEN() as suggested by Jakub
v2:
https://lore.kernel.org/all/20260528015913.190970-1-zhaochenguang@kylinos.cn/ (local)
v1:
https://lore.kernel.org/all/20260522054521.1169755-1-zhaochenguang@kylinos.cn/ (local)
---
net/netlabel/netlabel_unlabeled.c | 30 ++++++++++--------------------
1 file changed, 10 insertions(+), 20 deletions(-)
diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
index ca7a9e2a3de7..870e7699326a 100644
--- a/net/netlabel/netlabel_unlabeled.c
+++ b/net/netlabel/netlabel_unlabeled.c@@ -114,14 +114,14 @@ static struct genl_family netlbl_unlabel_gnl_family; /* NetLabel Netlink attribute policy */ static const struct nla_policy netlbl_unlabel_genl_policy[NLBL_UNLABEL_A_MAX + 1] = { [NLBL_UNLABEL_A_ACPTFLG] = { .type = NLA_U8 }, - [NLBL_UNLABEL_A_IPV6ADDR] = { .type = NLA_BINARY, - .len = sizeof(struct in6_addr) }, - [NLBL_UNLABEL_A_IPV6MASK] = { .type = NLA_BINARY, - .len = sizeof(struct in6_addr) }, - [NLBL_UNLABEL_A_IPV4ADDR] = { .type = NLA_BINARY, - .len = sizeof(struct in_addr) }, - [NLBL_UNLABEL_A_IPV4MASK] = { .type = NLA_BINARY, - .len = sizeof(struct in_addr) }, + [NLBL_UNLABEL_A_IPV6ADDR] = + NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)), + [NLBL_UNLABEL_A_IPV6MASK] = + NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)), + [NLBL_UNLABEL_A_IPV4ADDR] = + NLA_POLICY_EXACT_LEN(sizeof(struct in_addr)), + [NLBL_UNLABEL_A_IPV4MASK] = + NLA_POLICY_EXACT_LEN(sizeof(struct in_addr)), [NLBL_UNLABEL_A_IFACE] = { .type = NLA_NUL_STRING, .len = IFNAMSIZ - 1 }, [NLBL_UNLABEL_A_SECCTX] = { .type = NLA_BINARY }
@@ -757,24 +757,14 @@ static int netlbl_unlabel_addrinfo_get(struct genl_info *info, void **mask, u32 *len) { - u32 addr_len; - if (info->attrs[NLBL_UNLABEL_A_IPV4ADDR] && info->attrs[NLBL_UNLABEL_A_IPV4MASK]) { - addr_len = nla_len(info->attrs[NLBL_UNLABEL_A_IPV4ADDR]); - if (addr_len != sizeof(struct in_addr) && - addr_len != nla_len(info->attrs[NLBL_UNLABEL_A_IPV4MASK])) - return -EINVAL; - *len = addr_len; + *len = sizeof(struct in_addr); *addr = nla_data(info->attrs[NLBL_UNLABEL_A_IPV4ADDR]); *mask = nla_data(info->attrs[NLBL_UNLABEL_A_IPV4MASK]); return 0; } else if (info->attrs[NLBL_UNLABEL_A_IPV6ADDR]) { - addr_len = nla_len(info->attrs[NLBL_UNLABEL_A_IPV6ADDR]); - if (addr_len != sizeof(struct in6_addr) && - addr_len != nla_len(info->attrs[NLBL_UNLABEL_A_IPV6MASK])) - return -EINVAL; - *len = addr_len; + *len = sizeof(struct in6_addr); *addr = nla_data(info->attrs[NLBL_UNLABEL_A_IPV6ADDR]); *mask = nla_data(info->attrs[NLBL_UNLABEL_A_IPV6MASK]); return 0;
--
2.25.1