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| author | Kees Cook <keescook@chromium.org> | 2018-05-30 15:20:52 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-05-31 22:48:46 -0400 |
| commit | ccf8dbcd062a930e64741c939ca784d15316aa0c (patch) | |
| tree | 2ee1f0523cb121c01d5bc082875c1393ce8691dd | |
| parent | 7bb8c9969d919517fc379cacebd8fa93704173db (diff) | |
| download | nfc-next-ccf8dbcd062a930e64741c939ca784d15316aa0c.tar.gz | |
rtnetlink: Remove VLA usage
In the quest to remove all stack VLA usage from the kernel[1], this
allocates the maximum size expected for all possible types and adds
sanity-checks at both registration and usage to make sure nothing gets
out of sync. This matches the proposed VLA solution for nfnetlink[2]. The
values chosen here were based on finding assignments for .maxtype and
.slave_maxtype and manually counting the enums:
slave_maxtype (max 33):
IFLA_BRPORT_MAX 33
IFLA_BOND_SLAVE_MAX 9
maxtype (max 45):
IFLA_BOND_MAX 28
IFLA_BR_MAX 45
__IFLA_CAIF_HSI_MAX 8
IFLA_CAIF_MAX 4
IFLA_CAN_MAX 16
IFLA_GENEVE_MAX 12
IFLA_GRE_MAX 25
IFLA_GTP_MAX 5
IFLA_HSR_MAX 7
IFLA_IPOIB_MAX 4
IFLA_IPTUN_MAX 21
IFLA_IPVLAN_MAX 3
IFLA_MACSEC_MAX 15
IFLA_MACVLAN_MAX 7
IFLA_PPP_MAX 2
__IFLA_RMNET_MAX 4
IFLA_VLAN_MAX 6
IFLA_VRF_MAX 2
IFLA_VTI_MAX 7
IFLA_VXLAN_MAX 28
VETH_INFO_MAX 2
VXCAN_INFO_MAX 2
This additionally changes maxtype and slave_maxtype fields to unsigned,
since they're only ever using positive values.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
[2] https://patchwork.kernel.org/patch/10439647/
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/net/rtnetlink.h | 4 | ||||
| -rw-r--r-- | net/core/rtnetlink.c | 18 |
2 files changed, 18 insertions, 4 deletions
diff --git a/include/net/rtnetlink.h b/include/net/rtnetlink.h index 14b6b3af89188..0bbaa54884233 100644 --- a/include/net/rtnetlink.h +++ b/include/net/rtnetlink.h @@ -64,7 +64,7 @@ struct rtnl_link_ops { size_t priv_size; void (*setup)(struct net_device *dev); - int maxtype; + unsigned int maxtype; const struct nla_policy *policy; int (*validate)(struct nlattr *tb[], struct nlattr *data[], @@ -92,7 +92,7 @@ struct rtnl_link_ops { unsigned int (*get_num_tx_queues)(void); unsigned int (*get_num_rx_queues)(void); - int slave_maxtype; + unsigned int slave_maxtype; const struct nla_policy *slave_policy; int (*slave_changelink)(struct net_device *dev, struct net_device *slave_dev, diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 80802546c2797..8ca49a0e13fb3 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -59,6 +59,9 @@ #include <net/rtnetlink.h> #include <net/net_namespace.h> +#define RTNL_MAX_TYPE 48 +#define RTNL_SLAVE_MAX_TYPE 36 + struct rtnl_link { rtnl_doit_func doit; rtnl_dumpit_func dumpit; @@ -389,6 +392,11 @@ int rtnl_link_register(struct rtnl_link_ops *ops) { int err; + /* Sanity-check max sizes to avoid stack buffer overflow. */ + if (WARN_ON(ops->maxtype > RTNL_MAX_TYPE || + ops->slave_maxtype > RTNL_SLAVE_MAX_TYPE)) + return -EINVAL; + rtnl_lock(); err = __rtnl_link_register(ops); rtnl_unlock(); @@ -2902,13 +2910,16 @@ replay: } if (1) { - struct nlattr *attr[ops ? ops->maxtype + 1 : 1]; - struct nlattr *slave_attr[m_ops ? m_ops->slave_maxtype + 1 : 1]; + struct nlattr *attr[RTNL_MAX_TYPE + 1]; + struct nlattr *slave_attr[RTNL_SLAVE_MAX_TYPE + 1]; struct nlattr **data = NULL; struct nlattr **slave_data = NULL; struct net *dest_net, *link_net = NULL; if (ops) { + if (ops->maxtype > RTNL_MAX_TYPE) + return -EINVAL; + if (ops->maxtype && linkinfo[IFLA_INFO_DATA]) { err = nla_parse_nested(attr, ops->maxtype, linkinfo[IFLA_INFO_DATA], @@ -2925,6 +2936,9 @@ replay: } if (m_ops) { + if (ops->slave_maxtype > RTNL_SLAVE_MAX_TYPE) + return -EINVAL; + if (m_ops->slave_maxtype && linkinfo[IFLA_INFO_SLAVE_DATA]) { err = nla_parse_nested(slave_attr, |