From 67f83cbf081a70426ff667e8d14f94e13ed3bdca Mon Sep 17 00:00:00 2001 From: Venkat Yekkirala Date: Wed, 8 Nov 2006 17:04:26 -0600 Subject: SELinux: Fix SA selection semantics Fix the selection of an SA for an outgoing packet to be at the same context as the originating socket/flow. This eliminates the SELinux policy's ability to use/sendto SAs with contexts other than the socket's. With this patch applied, the SELinux policy will require one or more of the following for a socket to be able to communicate with/without SAs: 1. To enable a socket to communicate without using labeled-IPSec SAs: allow socket_t unlabeled_t:association { sendto recvfrom } 2. To enable a socket to communicate with labeled-IPSec SAs: allow socket_t self:association { sendto }; allow socket_t peer_sa_t:association { recvfrom }; Signed-off-by: Venkat Yekkirala Signed-off-by: James Morris --- security/selinux/xfrm.c | 101 +++++++++++++++++++++++------------------------- 1 file changed, 49 insertions(+), 52 deletions(-) (limited to 'security/selinux/xfrm.c') diff --git a/security/selinux/xfrm.c b/security/selinux/xfrm.c index 8fef74271f2..9b777140068 100644 --- a/security/selinux/xfrm.c +++ b/security/selinux/xfrm.c @@ -115,71 +115,40 @@ int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy * struct flowi *fl) { u32 state_sid; - u32 pol_sid; - int err; + int rc; - if (xp->security) { - if (!x->security) - /* unlabeled SA and labeled policy can't match */ - return 0; - else - state_sid = x->security->ctx_sid; - pol_sid = xp->security->ctx_sid; - } else + if (!xp->security) if (x->security) /* unlabeled policy and labeled SA can't match */ return 0; else /* unlabeled policy and unlabeled SA match all flows */ return 1; - - err = avc_has_perm(state_sid, pol_sid, SECCLASS_ASSOCIATION, - ASSOCIATION__POLMATCH, - NULL); - - if (err) - return 0; - - err = avc_has_perm(fl->secid, state_sid, SECCLASS_ASSOCIATION, - ASSOCIATION__SENDTO, - NULL)? 0:1; - - return err; -} - -/* - * LSM hook implementation that authorizes that a particular outgoing flow - * can use a given security association. - */ - -int selinux_xfrm_flow_state_match(struct flowi *fl, struct xfrm_state *xfrm, - struct xfrm_policy *xp) -{ - int rc = 0; - u32 sel_sid = SECINITSID_UNLABELED; - struct xfrm_sec_ctx *ctx; - - if (!xp->security) - if (!xfrm->security) - return 1; - else - return 0; else - if (!xfrm->security) + if (!x->security) + /* unlabeled SA and labeled policy can't match */ return 0; + else + if (!selinux_authorizable_xfrm(x)) + /* Not a SELinux-labeled SA */ + return 0; - /* Context sid is either set to label or ANY_ASSOC */ - if ((ctx = xfrm->security)) { - if (!selinux_authorizable_ctx(ctx)) - return 0; + state_sid = x->security->ctx_sid; - sel_sid = ctx->ctx_sid; - } + if (fl->secid != state_sid) + return 0; - rc = avc_has_perm(fl->secid, sel_sid, SECCLASS_ASSOCIATION, + rc = avc_has_perm(fl->secid, state_sid, SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO, NULL)? 0:1; + /* + * We don't need a separate SA Vs. policy polmatch check + * since the SA is now of the same label as the flow and + * a flow Vs. policy polmatch check had already happened + * in selinux_xfrm_policy_lookup() above. + */ + return rc; } @@ -481,6 +450,13 @@ int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb, } } + /* + * This check even when there's no association involved is + * intended, according to Trent Jaeger, to make sure a + * process can't engage in non-ipsec communication unless + * explicitly allowed by policy. + */ + rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION, ASSOCIATION__RECVFROM, ad); @@ -492,10 +468,10 @@ int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb, * If we have no security association, then we need to determine * whether the socket is allowed to send to an unlabelled destination. * If we do have a authorizable security association, then it has already been - * checked in xfrm_policy_lookup hook. + * checked in the selinux_xfrm_state_pol_flow_match hook above. */ int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb, - struct avc_audit_data *ad) + struct avc_audit_data *ad, u8 proto) { struct dst_entry *dst; int rc = 0; @@ -514,6 +490,27 @@ int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb, } } + switch (proto) { + case IPPROTO_AH: + case IPPROTO_ESP: + case IPPROTO_COMP: + /* + * We should have already seen this packet once before + * it underwent xfrm(s). No need to subject it to the + * unlabeled check. + */ + goto out; + default: + break; + } + + /* + * This check even when there's no association involved is + * intended, according to Trent Jaeger, to make sure a + * process can't engage in non-ipsec communication unless + * explicitly allowed by policy. + */ + rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO, ad); out: -- cgit v1.2.3-18-g5258