On 11/2/17 12:22 AM, David Miller wrote:
> I wish we could trap things like this using the policy,
> enforcing an exact size access for attributes such as
> these.
From feae5aa9dd7a26b7fbf33582738c7c89f068d81b Mon Sep 17 00:00:00 2001
From: David Ahern <dsah...@gmail.com>
Date: Thu, 2 Nov 2017 12:18:02 -0700
Subject: [PATCH net-next] net: netlink: Update attr validation to require
exact length for some types
Attributes using NLA_U* and NLA_S* (where * is 8, 16,32 and 64) are
expected to be an exact length. Spliti these data types from
nla_attr_minlen into nla_attr_len and update validate_nla to require
the attribute to have exact length for them.
Signed-off-by: David Ahern <dsah...@gmail.com>
---
lib/nlattr.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/lib/nlattr.c b/lib/nlattr.c
index 927c2f19f119..b5e360e7dfc8 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -14,19 +14,23 @@
#include <linux/types.h>
#include <net/netlink.h>
-static const u8 nla_attr_minlen[NLA_TYPE_MAX+1] = {
+/* for these data types attribute length must be exactly given size */
+static const u8 nla_attr_len[NLA_TYPE_MAX+1] = {
[NLA_U8] = sizeof(u8),
[NLA_U16] = sizeof(u16),
[NLA_U32] = sizeof(u32),
[NLA_U64] = sizeof(u64),
- [NLA_MSECS] = sizeof(u64),
- [NLA_NESTED] = NLA_HDRLEN,
[NLA_S8] = sizeof(s8),
[NLA_S16] = sizeof(s16),
[NLA_S32] = sizeof(s32),
[NLA_S64] = sizeof(s64),
};
+static const u8 nla_attr_minlen[NLA_TYPE_MAX+1] = {
+ [NLA_MSECS] = sizeof(u64),
+ [NLA_NESTED] = NLA_HDRLEN,
+};
+
static int validate_nla_bitfield32(const struct nlattr *nla,
u32 *valid_flags_allowed)
{
@@ -64,6 +68,13 @@ static int validate_nla(const struct nlattr *nla, int
maxtype,
BUG_ON(pt->type > NLA_TYPE_MAX);
+ /* for data types NLA_U* and NLA_S* require exact length */
+ if (nla_attr_len[pt->type]) {
+ if (attrlen != nla_attr_len[pt->type])
+ return -ERANGE;
+ return 0;
+ }
+
switch (pt->type) {
case NLA_FLAG:
if (attrlen > 0)
--
2.13.5 (Apple Git-94)
