xfrm: Treat already-verified secpath entries as optional

This change allows inbound traffic through nested IPsec tunnels to
successfully match policies and templates, while retaining the secpath
stack trace as necessary for netfilter policies.

Specifically, this patch marks secpath entries that have already matched
against a relevant policy as having been verified, allowing it to be
treated as optional and skipped after a tunnel decapsulation (during
which the src/dst/proto/etc may have changed, and the correct policy
chain no long be resolvable).

This approach is taken as opposed to the iteration in b0355dbbf13c,
where the secpath was cleared, since that breaks subsequent validations
that rely on the existence of the secpath entries (netfilter policies, or
transport-in-tunnel mode, where policies remain resolvable).

Fixes: b0355dbbf13c ("Fix XFRM-I support for nested ESP tunnels")
Test: Tested against Android Kernel Unit Tests
Test: Tested against Android CTS
Signed-off-by: Benedict Wong <benedictwong@google.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 33ee3f5936e6959ba8e27c08a5134428d96f3a01..151ca95dd08db32b7cf6db46ad441471dfffbc16 100644 (file)
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1054,6 +1054,7 @@ struct xfrm_offload {
 struct sec_path {
        int                     len;
        int                     olen;
+       int                     verified_cnt;
 
        struct xfrm_state       *xvec[XFRM_MAX_DEPTH];
        struct xfrm_offload     ovec[XFRM_MAX_OFFLOAD_DEPTH];

diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 39fb91ff23d96d3507b8cea9b2c73bc0defb8e5c..b731687b5f3ef10f6b56606a0dd7c5b0507c9023 100644 (file)
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -131,6 +131,7 @@ struct sec_path *secpath_set(struct sk_buff *skb)
        memset(sp->ovec, 0, sizeof(sp->ovec));
        sp->olen = 0;
        sp->len = 0;
+       sp->verified_cnt = 0;
 
        return sp;
 }

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 6d15788b512315f030899998354a7c8f4edc4e8c..ff58ce6c030cada39e93e342031404b4861c75e0 100644 (file)
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3349,6 +3349,13 @@ xfrm_policy_ok(const struct xfrm_tmpl *tmpl, const struct sec_path *sp, int star
                if (xfrm_state_ok(tmpl, sp->xvec[idx], family, if_id))
                        return ++idx;
                if (sp->xvec[idx]->props.mode != XFRM_MODE_TRANSPORT) {
+                       if (idx < sp->verified_cnt) {
+                               /* Secpath entry previously verified, consider optional and
+                                * continue searching
+                                */
+                               continue;
+                       }
+
                        if (start == -1)
                                start = -2-idx;
                        break;
@@ -3723,6 +3730,9 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
                 * Order is _important_. Later we will implement
                 * some barriers, but at the moment barriers
                 * are implied between each two transformations.
+                * Upon success, marks secpath entries as having been
+                * verified to allow them to be skipped in future policy
+                * checks (e.g. nested tunnels).
                 */
                for (i = xfrm_nr-1, k = 0; i >= 0; i--) {
                        k = xfrm_policy_ok(tpp[i], sp, k, family, if_id);
@@ -3741,6 +3751,8 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
                }
 
                xfrm_pols_put(pols, npols);
+               sp->verified_cnt = k;
+
                return 1;
        }
        XFRM_INC_STATS(net, LINUX_MIB_XFRMINPOLBLOCK);