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ipv4: validate IPV4_DEVCONF attributes properly

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As the IPV4_DEVCONF netlink attributes are not being validated, it is
possible to use netlink to set read-only values like mc_forwarding. In
addition, valid ranges are not being validated neither but that is less
relevant as they aren't in sysctl.

To avoid similar situations in the future, define a NLA policy for
IPV4_DEVCONF attributes which are nested in IFLA_INET_CONF.

Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Link: https://patch.msgid.link/20260312142637.5704-1-fmancera@suse.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Fernando Fernandez Mancera
2026-03-12 15:26:37 +01:00
committed by Jakub Kicinski
parent f807b5b9b8
commit fa8fca8871
1 changed files with 45 additions and 10 deletions
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55
net/ipv4/devinet.c
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@@ -2063,12 +2063,50 @@ static const struct nla_policy inet_af_policy[IFLA_INET_MAX+1] = {
[IFLA_INET_CONF] = { .type = NLA_NESTED },
};
static const struct nla_policy inet_devconf_policy[IPV4_DEVCONF_MAX + 1] = {
[IPV4_DEVCONF_FORWARDING] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_MC_FORWARDING] = { .type = NLA_REJECT },
[IPV4_DEVCONF_PROXY_ARP] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_ACCEPT_REDIRECTS] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_SECURE_REDIRECTS] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_SEND_REDIRECTS] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_SHARED_MEDIA] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_RP_FILTER] = NLA_POLICY_RANGE(NLA_U32, 0, 2),
[IPV4_DEVCONF_ACCEPT_SOURCE_ROUTE] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_BOOTP_RELAY] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_LOG_MARTIANS] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_TAG] = { .type = NLA_U32 },
[IPV4_DEVCONF_ARPFILTER] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_MEDIUM_ID] = NLA_POLICY_MIN(NLA_S32, -1),
[IPV4_DEVCONF_NOXFRM] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_NOPOLICY] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_FORCE_IGMP_VERSION] = NLA_POLICY_RANGE(NLA_U32, 0, 3),
[IPV4_DEVCONF_ARP_ANNOUNCE] = NLA_POLICY_RANGE(NLA_U32, 0, 2),
[IPV4_DEVCONF_ARP_IGNORE] = NLA_POLICY_RANGE(NLA_U32, 0, 8),
[IPV4_DEVCONF_PROMOTE_SECONDARIES] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_ARP_ACCEPT] = NLA_POLICY_RANGE(NLA_U32, 0, 2),
[IPV4_DEVCONF_ARP_NOTIFY] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_ACCEPT_LOCAL] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_SRC_VMARK] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_PROXY_ARP_PVLAN] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_ROUTE_LOCALNET] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_BC_FORWARDING] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_IGMPV2_UNSOLICITED_REPORT_INTERVAL] = { .type = NLA_U32 },
[IPV4_DEVCONF_IGMPV3_UNSOLICITED_REPORT_INTERVAL] = { .type = NLA_U32 },
[IPV4_DEVCONF_IGNORE_ROUTES_WITH_LINKDOWN] =
NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_DROP_UNICAST_IN_L2_MULTICAST] =
NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_DROP_GRATUITOUS_ARP] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
[IPV4_DEVCONF_ARP_EVICT_NOCARRIER] = NLA_POLICY_RANGE(NLA_U32, 0, 1),
};
static int inet_validate_link_af(const struct net_device *dev,
const struct nlattr *nla,
struct netlink_ext_ack *extack)
{
struct nlattr *a, *tb[IFLA_INET_MAX+1];
int err, rem;
struct nlattr *tb[IFLA_INET_MAX + 1], *nested_tb[IPV4_DEVCONF_MAX + 1];
int err;
if (dev && !__in_dev_get_rtnl(dev))
return -EAFNOSUPPORT;
@@ -2079,15 +2117,12 @@ static int inet_validate_link_af(const struct net_device *dev,
return err;
if (tb[IFLA_INET_CONF]) {
nla_for_each_nested(a, tb[IFLA_INET_CONF], rem) {
int cfgid = nla_type(a);
err = nla_parse_nested(nested_tb, IPV4_DEVCONF_MAX,
tb[IFLA_INET_CONF], inet_devconf_policy,
extack);
if (nla_len(a) < 4)
return -EINVAL;
if (cfgid <= 0 || cfgid > IPV4_DEVCONF_MAX)
return -EINVAL;
}
if (err < 0)
return err;
}
return 0;