diff mbox series

[1/6] xfrm: Treat already-verified secpath entries as optional

Message ID 20230620103430.1975055-2-steffen.klassert@secunet.com (mailing list archive)
State Awaiting Upstream
Delegated to: Netdev Maintainers
Headers show
Series [1/6] xfrm: Treat already-verified secpath entries as optional | expand

Checks

Context Check Description
netdev/series_format warning Pull request is its own cover letter; Target tree name not specified in the subject
netdev/tree_selection success Guessed tree name to be net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 245 this patch: 245
netdev/cc_maintainers fail 1 blamed authors not CCed: benedictwong@google.com; 3 maintainers not CCed: pabeni@redhat.com edumazet@google.com benedictwong@google.com
netdev/build_clang success Errors and warnings before: 12 this patch: 12
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 234 this patch: 234
netdev/checkpatch warning WARNING: line length of 91 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Steffen Klassert June 20, 2023, 10:34 a.m. UTC 
From: Benedict Wong <benedictwong@google.com>

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>
---
 include/net/xfrm.h     |  1 +
 net/xfrm/xfrm_input.c  |  1 +
 net/xfrm/xfrm_policy.c | 12 ++++++++++++
 3 files changed, 14 insertions(+)
diff mbox series

Patch

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 33ee3f5936e6..151ca95dd08d 100644
--- 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 39fb91ff23d9..b731687b5f3e 100644
--- 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 6d15788b5123..ff58ce6c030c 100644
--- 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);