[PATCH 5.10 081/142] xfrm: Fix wraparound in xfrm_policy_addr_delta()

Greg Kroah-Hartman
2021-02-02T14:00:27Z

From: Visa Hankala <visa@hankala.org>

[ Upstream commit da64ae2d35d3673233f0403b035d4c6acbf71965 ]

Use three-way comparison for address components to avoid integer
wraparound in the result of xfrm_policy_addr_delta(). This ensures
that the search trees are built and traversed correctly.

Treat IPv4 and IPv6 similarly by returning 0 when prefixlen == 0.
Prefix /0 has only one equivalence class.

Fixes: 9cf545ebd591d ("xfrm: policy: store inexact policies in a tree ordered by destination address")
Signed-off-by: Visa Hankala <visa@hankala.org>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/xfrm/xfrm_policy.c | 26 +++++++++----
tools/testing/selftests/net/xfrm_policy.sh | 43 ++++++++++++++++++++++
2 files changed, 61 insertions(+), 8 deletions(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 2f84136af48ab..b74f28cabe24f 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -793,15 +793,22 @@ static int xfrm_policy_addr_delta(const xfrm_address_t *a,
const xfrm_address_t *b,
u8 prefixlen, u16 family)
{
+ u32 ma, mb, mask;
unsigned int pdw, pbi;
int delta = 0;

switch (family) {
case AF_INET:
- if (sizeof(long) == 4 && prefixlen == 0)
- return ntohl(a->a4) - ntohl(b->a4);
- return (ntohl(a->a4) & ((~0UL << (32 - prefixlen)))) -
- (ntohl(b->a4) & ((~0UL << (32 - prefixlen))));
+ if (prefixlen == 0)
+ return 0;
+ mask = ~0U << (32 - prefixlen);
+ ma = ntohl(a->a4) & mask;
+ mb = ntohl(b->a4) & mask;
+ if (ma < mb)
+ delta = -1;
+ else if (ma > mb)
+ delta = 1;
+ break;
case AF_INET6:
pdw = prefixlen >> 5;
pbi = prefixlen & 0x1f;
@@ -812,10 +819,13 @@ static int xfrm_policy_addr_delta(const xfrm_address_t *a,
return delta;
}
if (pbi) {
- u32 mask = ~0u << (32 - pbi);
-
- delta = (ntohl(a->a6[pdw]) & mask) -
- (ntohl(b->a6[pdw]) & mask);
+ mask = ~0U << (32 - pbi);
+ ma = ntohl(a->a6[pdw]) & mask;
+ mb = ntohl(b->a6[pdw]) & mask;
+ if (ma < mb)
+ delta = -1;
+ else if (ma > mb)
+ delta = 1;
}
break;
default:
diff --git a/tools/testing/selftests/net/xfrm_policy.sh b/tools/testing/selftests/net/xfrm_policy.sh
index 5922941e70c6c..bdf450eaf60cf 100755
--- a/tools/testing/selftests/net/xfrm_policy.sh
+++ b/tools/testing/selftests/net/xfrm_policy.sh
@@ -287,6 +287,47 @@ check_hthresh_repeat()
return 0
}

+# insert non-overlapping policies in a random order and check that
+# all of them can be fetched using the traffic selectors.
+check_random_order()
+{
+ local ns=$1
+ local log=$2
+
+ for i in $(seq 100); do
+ ip -net $ns xfrm policy flush
+ for j in $(seq 0 16 255 | sort -R); do
+ ip -net $ns xfrm policy add dst $j.0.0.0/24 dir out priority 10 action allow
+ done
+ for j in $(seq 0 16 255); do
+ if ! ip -net $ns xfrm policy get dst $j.0.0.0/24 dir out > /dev/null; then
+ echo "FAIL: $log" 1>&2
+ return 1
+ fi
+ done
+ done
+
+ for i in $(seq 100); do
+ ip -net $ns xfrm policy flush
+ for j in $(seq 0 16 255 | sort -R); do
+ local addr=$(printf "e000:0000:%02x00::/56" $j)
+ ip -net $ns xfrm policy add dst $addr dir out priority 10 action allow
+ done
+ for j in $(seq 0 16 255); do
+ local addr=$(printf "e000:0000:%02x00::/56" $j)
+ if ! ip -net $ns xfrm policy get dst $addr dir out > /dev/null; then
+ echo "FAIL: $log" 1>&2
+ return 1
+ fi
+ done
+ done
+
+ ip -net $ns xfrm policy flush
+
+ echo "PASS: $log"
+ return 0
+}
+
#check for needed privileges
if [ "$(id -u)" -ne 0 ];then
echo "SKIP: Need root privileges"
@@ -438,6 +479,8 @@ check_exceptions "exceptions and block policies after htresh change to normal"

check_hthresh_repeat "policies with repeated htresh change"

+check_random_order ns3 "policies inserted in random order"
+
for i in 1 2 3 4;do ip netns del ns$i;done

exit $ret
--
2.27.0