From: Stephen Smalley <sds@tycho.nsa.gov> To: netdev@vger.kernel.org Cc: linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov, fw@strlen.de, davem@davemloft.net, herbert@gondor.apana.org.au, steffen.klassert@secunet.com, paul@paul-moore.com, Stephen Smalley <sds@tycho.nsa.gov> Subject: [RFC PATCH] xfrm: fix regression introduced by xdst pcpu cache Date: Mon, 30 Oct 2017 10:58:43 -0400 [thread overview] Message-ID: <20171030145843.13496-1-sds@tycho.nsa.gov> (raw) Since 4.14-rc1, the selinux-testsuite has been encountering sporadic failures during testing of labeled IPSEC. git bisect pointed to commit ec30d78c14a813db39a647b6a348b4286 ("xfrm: add xdst pcpu cache"). The xdst pcpu cache is only checking that the policies are the same, but does not validate that the policy, state, and flow match with respect to security context labeling. As a result, the wrong SA could be used and the receiver could end up performing permission checking and providing SO_PEERSEC or SCM_SECURITY values for the wrong security context. security_xfrm_state_pol_flow_match() exists for this purpose and is already called from xfrm_state_look_at() for matching purposes. Further, xfrm_state_look_at() also performs a xfrm_selector_match() test, which is also missing from the xdst pcpu cache logic. Add calls to both of these functions when validating the cache entry. With these changes, the selinux-testsuite passes all tests again. Fixes: ec30d78c14a813db39a647b6a348b4286ba4abf5 ("xfrm: add xdst pcpu cache") Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> --- This is an RFC because I am not entirely confident in the fix, e.g. is it sufficient to perform this matching only on the first xfrm or do they all need to be walked as in xfrm_bundle_ok()? Also, should we perform this matching before (as in this patch) or after calling xfrm_bundle_ok()? Also, do we need to test xfrm->sel.family before calling xfrm_selector_match (as in this patch) or not - xfrm_state_look_at() does so when the state is XFRM_STATE_VALID but not when it is _ERROR or _EXPIRED? net/xfrm/xfrm_policy.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 2746b62..171818b 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -1820,6 +1820,11 @@ xfrm_resolve_and_create_bundle(struct xfrm_policy **pols, int num_pols, !xfrm_pol_dead(xdst) && memcmp(xdst->pols, pols, sizeof(struct xfrm_policy *) * num_pols) == 0 && + (!xdst->u.dst.xfrm->sel.family || + xfrm_selector_match(&xdst->u.dst.xfrm->sel, fl, + xdst->u.dst.xfrm->sel.family)) && + security_xfrm_state_pol_flow_match(xdst->u.dst.xfrm, + xdst->pols[0], fl) && xfrm_bundle_ok(xdst)) { dst_hold(&xdst->u.dst); return xdst; -- 2.9.5
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From: sds@tycho.nsa.gov (Stephen Smalley) To: linux-security-module@vger.kernel.org Subject: [RFC PATCH] xfrm: fix regression introduced by xdst pcpu cache Date: Mon, 30 Oct 2017 10:58:43 -0400 [thread overview] Message-ID: <20171030145843.13496-1-sds@tycho.nsa.gov> (raw) Since 4.14-rc1, the selinux-testsuite has been encountering sporadic failures during testing of labeled IPSEC. git bisect pointed to commit ec30d78c14a813db39a647b6a348b4286 ("xfrm: add xdst pcpu cache"). The xdst pcpu cache is only checking that the policies are the same, but does not validate that the policy, state, and flow match with respect to security context labeling. As a result, the wrong SA could be used and the receiver could end up performing permission checking and providing SO_PEERSEC or SCM_SECURITY values for the wrong security context. security_xfrm_state_pol_flow_match() exists for this purpose and is already called from xfrm_state_look_at() for matching purposes. Further, xfrm_state_look_at() also performs a xfrm_selector_match() test, which is also missing from the xdst pcpu cache logic. Add calls to both of these functions when validating the cache entry. With these changes, the selinux-testsuite passes all tests again. Fixes: ec30d78c14a813db39a647b6a348b4286ba4abf5 ("xfrm: add xdst pcpu cache") Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> --- This is an RFC because I am not entirely confident in the fix, e.g. is it sufficient to perform this matching only on the first xfrm or do they all need to be walked as in xfrm_bundle_ok()? Also, should we perform this matching before (as in this patch) or after calling xfrm_bundle_ok()? Also, do we need to test xfrm->sel.family before calling xfrm_selector_match (as in this patch) or not - xfrm_state_look_at() does so when the state is XFRM_STATE_VALID but not when it is _ERROR or _EXPIRED? net/xfrm/xfrm_policy.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 2746b62..171818b 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -1820,6 +1820,11 @@ xfrm_resolve_and_create_bundle(struct xfrm_policy **pols, int num_pols, !xfrm_pol_dead(xdst) && memcmp(xdst->pols, pols, sizeof(struct xfrm_policy *) * num_pols) == 0 && + (!xdst->u.dst.xfrm->sel.family || + xfrm_selector_match(&xdst->u.dst.xfrm->sel, fl, + xdst->u.dst.xfrm->sel.family)) && + security_xfrm_state_pol_flow_match(xdst->u.dst.xfrm, + xdst->pols[0], fl) && xfrm_bundle_ok(xdst)) { dst_hold(&xdst->u.dst); return xdst; -- 2.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
next reply other threads:[~2017-10-30 14:58 UTC|newest] Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-10-30 14:58 Stephen Smalley [this message] 2017-10-30 14:58 ` [RFC PATCH] xfrm: fix regression introduced by xdst pcpu cache Stephen Smalley 2017-10-31 11:11 ` Florian Westphal 2017-10-31 11:11 ` Florian Westphal [not found] ` <20171031111122.GB7663-E0PNVn5OA6ohrxcnuTQ+TQ@public.gmane.org> 2017-10-31 13:43 ` Stephen Smalley 2017-10-31 13:43 ` Stephen Smalley 2017-10-31 13:43 ` Stephen Smalley 2017-10-31 14:00 ` Stephen Smalley 2017-10-31 14:00 ` Stephen Smalley 2017-10-31 14:15 ` Florian Westphal 2017-10-31 14:15 ` Florian Westphal 2017-10-31 20:39 ` Paul Moore 2017-10-31 20:39 ` Paul Moore 2017-10-31 23:08 ` Florian Westphal 2017-10-31 23:08 ` Florian Westphal 2017-11-01 14:05 ` Stephen Smalley 2017-11-01 14:05 ` Stephen Smalley 2017-11-01 21:39 ` Paul Moore 2017-11-01 21:39 ` Paul Moore 2017-11-02 12:58 ` Stephen Smalley 2017-11-02 12:58 ` Stephen Smalley 2017-11-02 22:37 ` Paul Moore 2017-11-02 22:37 ` Paul Moore -- strict thread matches above, loose matches on Subject: below -- 2017-10-27 15:28 Stephen Smalley 2017-10-27 15:28 ` Stephen Smalley
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