From 2d151d39073aff498358543801fca0f670fea981 Mon Sep 17 00:00:00 2001 From: Steffen Klassert Date: Sun, 18 Jul 2021 09:11:06 +0200 Subject: xfrm: Add possibility to set the default to block if we have no policy As the default we assume the traffic to pass, if we have no matching IPsec policy. With this patch, we have a possibility to change this default from allow to block. It can be configured via netlink. Each direction (input/output/forward) can be configured separately. With the default to block configuered, we need allow policies for all packet flows we accept. We do not use default policy lookup for the loopback device. v1->v2 - fix compiling when XFRM is disabled - Reported-by: kernel test robot Co-developed-by: Christian Langrock Signed-off-by: Christian Langrock Co-developed-by: Antony Antony Signed-off-by: Antony Antony Signed-off-by: Steffen Klassert --- net/xfrm/xfrm_policy.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'net/xfrm/xfrm_policy.c') diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 827d84255021..d5cb082e11fc 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -3165,6 +3165,11 @@ ok: return dst; nopol: + if (!(dst_orig->dev->flags & IFF_LOOPBACK) && + !xfrm_default_allow(net, dir)) { + err = -EPERM; + goto error; + } if (!(flags & XFRM_LOOKUP_ICMP)) { dst = dst_orig; goto ok; @@ -3553,6 +3558,11 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb, } if (!pol) { + if (!xfrm_default_allow(net, dir)) { + XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOPOLS); + return 0; + } + if (sp && secpath_has_nontransport(sp, 0, &xerr_idx)) { xfrm_secpath_reject(xerr_idx, skb, &fl); XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOPOLS); @@ -3607,6 +3617,12 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb, tpp[ti++] = &pols[pi]->xfrm_vec[i]; } xfrm_nr = ti; + + if (!xfrm_default_allow(net, dir) && !xfrm_nr) { + XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES); + goto reject; + } + if (npols > 1) { xfrm_tmpl_sort(stp, tpp, xfrm_nr, family); tpp = stp; -- cgit