selftests/net: convert xfrm_policy.sh to run it in unique namespace

Here is the test result after conversion.

# ./xfrm_policy.sh
PASS: policy before exception matches
PASS: ping to .254 bypassed ipsec tunnel (exceptions)
PASS: direct policy matches (exceptions)
PASS: policy matches (exceptions)
PASS: ping to .254 bypassed ipsec tunnel (exceptions and block policies)
PASS: direct policy matches (exceptions and block policies)
PASS: policy matches (exceptions and block policies)
PASS: ping to .254 bypassed ipsec tunnel (exceptions and block policies after hresh changes)
PASS: direct policy matches (exceptions and block policies after hresh changes)
PASS: policy matches (exceptions and block policies after hresh changes)
PASS: ping to .254 bypassed ipsec tunnel (exceptions and block policies after hthresh change in ns3)
PASS: direct policy matches (exceptions and block policies after hthresh change in ns3)
PASS: policy matches (exceptions and block policies after hthresh change in ns3)
PASS: ping to .254 bypassed ipsec tunnel (exceptions and block policies after htresh change to normal)
PASS: direct policy matches (exceptions and block policies after htresh change to normal)
PASS: policy matches (exceptions and block policies after htresh change to normal)
PASS: policies with repeated htresh change

Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xfrm: Fix wraparound in xfrm_policy_addr_delta()

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>

selftests: xfrm: fix test return value override issue in xfrm_policy.sh

When running this xfrm_policy.sh test script, even with some cases
marked as FAIL, the overall test result will still be PASS:

$ sudo ./xfrm_policy.sh
PASS: policy before exception matches
FAIL: expected ping to .254 to fail (exceptions)
PASS: direct policy matches (exceptions)
PASS: policy matches (exceptions)
FAIL: expected ping to .254 to fail (exceptions and block policies)
PASS: direct policy matches (exceptions and block policies)
PASS: policy matches (exceptions and block policies)
FAIL: expected ping to .254 to fail (exceptions and block policies after hresh changes)
PASS: direct policy matches (exceptions and block policies after hresh changes)
PASS: policy matches (exceptions and block policies after hresh changes)
FAIL: expected ping to .254 to fail (exceptions and block policies after hthresh change in ns3)
PASS: direct policy matches (exceptions and block policies after hthresh change in ns3)
PASS: policy matches (exceptions and block policies after hthresh change in ns3)
FAIL: expected ping to .254 to fail (exceptions and block policies after htresh change to normal)
PASS: direct policy matches (exceptions and block policies after htresh change to normal)
PASS: policy matches (exceptions and block policies after htresh change to normal)
PASS: policies with repeated htresh change
$ echo $?
0

This is because the $lret in check_xfrm() is not a local variable.
Therefore when a test failed in check_exceptions(), the non-zero $lret
will later get reset to 0 when the next test calls check_xfrm().

With this fix, the final return value will be 1. Make it easier for
testers to spot this failure.

Fixes: 39aa6928d462d0 ("xfrm: policy: fix netlink/pf_key policy lookups")
Signed-off-by: Po-Hsu Lin <po-hsu.lin@canonical.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

xfrm: policy: avoid warning splat when merging nodes

syzbot reported a splat:
xfrm_policy_inexact_list_reinsert+0x625/0x6e0 net/xfrm/xfrm_policy.c:877
CPU: 1 PID: 6756 Comm: syz-executor.1 Not tainted 5.3.0-rc2+ #57
Call Trace:
xfrm_policy_inexact_node_reinsert net/xfrm/xfrm_policy.c:922 [inline]
xfrm_policy_inexact_node_merge net/xfrm/xfrm_policy.c:958 [inline]
xfrm_policy_inexact_insert_node+0x537/0xb50 net/xfrm/xfrm_policy.c:1023
xfrm_policy_inexact_alloc_chain+0x62b/0xbd0 net/xfrm/xfrm_policy.c:1139
xfrm_policy_inexact_insert+0xe8/0x1540 net/xfrm/xfrm_policy.c:1182
xfrm_policy_insert+0xdf/0xce0 net/xfrm/xfrm_policy.c:1574
xfrm_add_policy+0x4cf/0x9b0 net/xfrm/xfrm_user.c:1670
xfrm_user_rcv_msg+0x46b/0x720 net/xfrm/xfrm_user.c:2676
netlink_rcv_skb+0x1f0/0x460 net/netlink/af_netlink.c:2477
xfrm_netlink_rcv+0x74/0x90 net/xfrm/xfrm_user.c:2684
netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
netlink_unicast+0x809/0x9a0 net/netlink/af_netlink.c:1328
netlink_sendmsg+0xa70/0xd30 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:637 [inline]
sock_sendmsg net/socket.c:657 [inline]

There is no reproducer, however, the warning can be reproduced
by adding rules with ever smaller prefixes.

The sanity check ("does the policy match the node") uses the prefix value
of the node before its updated to the smaller value.

To fix this, update the prefix earlier. The bug has no impact on tree
correctness, this is only to prevent a false warning.

Reported-by: syzbot+8cc27ace5f6972910b31@syzkaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

xfrm: policy: fix bydst hlist corruption on hash rebuild

syzbot reported following spat:

BUG: KASAN: use-after-free in __write_once_size include/linux/compiler.h:221
BUG: KASAN: use-after-free in hlist_del_rcu include/linux/rculist.h:455
BUG: KASAN: use-after-free in xfrm_hash_rebuild+0xa0d/0x1000 net/xfrm/xfrm_policy.c:1318
Write of size 8 at addr ffff888095e79c00 by task kworker/1:3/8066
Workqueue: events xfrm_hash_rebuild
Call Trace:
__write_once_size include/linux/compiler.h:221 [inline]
hlist_del_rcu include/linux/rculist.h:455 [inline]
xfrm_hash_rebuild+0xa0d/0x1000 net/xfrm/xfrm_policy.c:1318
process_one_work+0x814/0x1130 kernel/workqueue.c:2269
Allocated by task 8064:
__kmalloc+0x23c/0x310 mm/slab.c:3669
kzalloc include/linux/slab.h:742 [inline]
xfrm_hash_alloc+0x38/0xe0 net/xfrm/xfrm_hash.c:21
xfrm_policy_init net/xfrm/xfrm_policy.c:4036 [inline]
xfrm_net_init+0x269/0xd60 net/xfrm/xfrm_policy.c:4120
ops_init+0x336/0x420 net/core/net_namespace.c:130
setup_net+0x212/0x690 net/core/net_namespace.c:316

The faulting address is the address of the old chain head,
free'd by xfrm_hash_resize().

In xfrm_hash_rehash(), chain heads get re-initialized without
any hlist_del_rcu:

for (i = hmask; i >= 0; i--)
INIT_HLIST_HEAD(odst + i);

Then, hlist_del_rcu() gets called on the about to-be-reinserted policy
when iterating the per-net list of policies.

hlist_del_rcu() will then make chain->first be nonzero again:

static inline void __hlist_del(struct hlist_node *n)
{
struct hlist_node *next = n->next; // address of next element in list
struct hlist_node **pprev = n->pprev;// location of previous elem, this
// can point at chain->first
WRITE_ONCE(*pprev, next); // chain->first points to next elem
if (next)
next->pprev = pprev;

Then, when we walk chainlist to find insertion point, we may find a
non-empty list even though we're supposedly reinserting the first
policy to an empty chain.

To fix this first unlink all exact and inexact policies instead of
zeroing the list heads.

Add the commands equivalent to the syzbot reproducer to xfrm_policy.sh,
without fix KASAN catches the corruption as it happens, SLUB poisoning
detects it a bit later.

Reported-by: syzbot+0165480d4ef07360eeda@syzkaller.appspotmail.com
Fixes: 1548bc4e0512 ("xfrm: policy: delete inexact policies from inexact list on hash rebuild")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

xfrm: policy: fix infinite loop when merging src-nodes

With very small change to test script we can trigger softlockup due to
bogus assignment of 'p' (policy to be examined) on restart.

Previously the two to-be-merged nodes had same address/prefixlength pair,
so no erase/reinsert was necessary, we only had to append the list from
node a to b.

If prefix lengths are different, the node has to be deleted and re-inserted
into the tree, with the updated prefix length. This was broken; due to
bogus update to 'p' this loops forever.

Add a 'restart' label and use that instead.

While at it, don't perform the unneeded reinserts of the policies that
are already sorted into the 'new' node.

A previous patch in this series made xfrm_policy_inexact_list_reinsert()
use the relative position indicator to sort policies according to age in
case priorities are identical.

Fixes: 6ac098b2a9d30 ("xfrm: policy: add 2nd-level saddr trees for inexact policies")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

selftests: xfrm: alter htresh to trigger move of policies to hash table

... and back to inexact tree.
Repeat ping test after each htresh change: lookup results must not change.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

selftests: xfrm: add block rules with adjacent/overlapping subnets

The existing script lacks a policy pattern that triggers 'tree node
merges' in the kernel.

Consider adding policy affecting following subnet:
pol1: dst 10.0.0.0/22
pol2: dst 10.0.0.0/23 # adds to existing 10.0.0.0/22 node

-> no problems here. But now, lets consider reverse order:
pol1: dst 10.0.0.0/24
pol2: dst 10.0.0.0/23 # CANNOT add to existing node

When second policy gets added, the kernel must check that the new node
("10.0.0.0/23") doesn't overlap with any existing subnet.

Example:
dst 10.0.0.0/24
dst 10.0.0.1/24
dst 10.0.0.0/23

When the third policy gets added, the kernel must replace the nodes for
the 10.0.0.0/24 and 10.0.0.1/24 policies with a single one and must merge
all the subtrees/lists stored in those nodes into the new node.

The existing test cases only have overlaps with a single node, so no
merging takes place (we can always remove the 'old' node and replace
it with the new subnet prefix).

Add a few 'block policies' in a pattern that triggers this, with a priority
that will make kernel prefer the 'esp' rules.

Make sure the 'tunnel ping' tests still pass after they have been added.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

xfrm: policy: fix netlink/pf_key policy lookups

Colin Ian King says:
Static analysis with CoverityScan found a potential issue [..]
It seems that pointer pol is set to NULL and then a check to see if it
is non-null is used to set pol to tmp; howeverm this check is always
going to be false because pol is always NULL.

Fix this and update test script to catch this. Updated script only:
./xfrm_policy.sh ; echo $?
RTNETLINK answers: No such file or directory
FAIL: ip -net ns3 xfrm policy get src 10.0.1.0/24 dst 10.0.2.0/24 dir out
RTNETLINK answers: No such file or directory
[..]
PASS: policy before exception matches
PASS: ping to .254 bypassed ipsec tunnel
PASS: direct policy matches
PASS: policy matches
1

Fixes: 6be3b0db6db ("xfrm: policy: add inexact policy search tree infrastructure")
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

selftests: add xfrm policy test script

add a script that adds a ipsec tunnel between two network
namespaces plus following policies:

.0/24 -> ipsec tunnel
.240/28 -> bypass
.253/32 -> ipsec tunnel

Then check that .254 bypasses tunnel (match /28 exception),
and .2 (match /24) and .253 (match direct policy) pass through the
tunnel.

Abuses iptables to check if ping did resolve an ipsec policy or not.

Also adds a bunch of 'block' rules that are not supposed to match.

Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>