From e0d1caa7b0d5f02e4f34aa09c695d04251310c6c Mon Sep 17 00:00:00 2001 From: Venkat Yekkirala Date: Mon, 24 Jul 2006 23:29:07 -0700 Subject: [MLSXFRM]: Flow based matching of xfrm policy and state This implements a seemless mechanism for xfrm policy selection and state matching based on the flow sid. This also includes the necessary SELinux enforcement pieces. Signed-off-by: Venkat Yekkirala Signed-off-by: David S. Miller --- security/selinux/xfrm.c | 199 ++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 166 insertions(+), 33 deletions(-) (limited to 'security/selinux/xfrm.c') diff --git a/security/selinux/xfrm.c b/security/selinux/xfrm.c index 6c985ced8102..a502b0540e3d 100644 --- a/security/selinux/xfrm.c +++ b/security/selinux/xfrm.c @@ -6,7 +6,12 @@ * Authors: Serge Hallyn * Trent Jaeger * + * Updated: Venkat Yekkirala + * + * Granular IPSec Associations for use in MLS environments. + * * Copyright (C) 2005 International Business Machines Corporation + * Copyright (C) 2006 Trusted Computer Solutions, Inc. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2, @@ -67,10 +72,10 @@ static inline int selinux_authorizable_xfrm(struct xfrm_state *x) } /* - * LSM hook implementation that authorizes that a socket can be used - * with the corresponding xfrm_sec_ctx and direction. + * LSM hook implementation that authorizes that a flow can use + * a xfrm policy rule. */ -int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 sk_sid, u8 dir) +int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir) { int rc = 0; u32 sel_sid = SECINITSID_UNLABELED; @@ -84,27 +89,129 @@ int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 sk_sid, u8 dir) sel_sid = ctx->ctx_sid; } - rc = avc_has_perm(sk_sid, sel_sid, SECCLASS_ASSOCIATION, - ((dir == FLOW_DIR_IN) ? ASSOCIATION__RECVFROM : - ((dir == FLOW_DIR_OUT) ? ASSOCIATION__SENDTO : - (ASSOCIATION__SENDTO | ASSOCIATION__RECVFROM))), + rc = avc_has_perm(fl_secid, sel_sid, SECCLASS_ASSOCIATION, + ASSOCIATION__POLMATCH, NULL); return rc; } +/* + * LSM hook implementation that authorizes that a state matches + * the given policy, flow combo. + */ + +int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *xp, + struct flowi *fl) +{ + u32 state_sid; + u32 pol_sid; + int err; + + if (x->security) + state_sid = x->security->ctx_sid; + else + state_sid = SECINITSID_UNLABELED; + + if (xp->security) + pol_sid = xp->security->ctx_sid; + else + pol_sid = SECINITSID_UNLABELED; + + err = avc_has_perm(state_sid, pol_sid, SECCLASS_ASSOCIATION, + ASSOCIATION__POLMATCH, + NULL); + + if (err) + return 0; + + return selinux_xfrm_flow_state_match(fl, x); +} + +/* + * 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) +{ + int rc = 0; + u32 sel_sid = SECINITSID_UNLABELED; + struct xfrm_sec_ctx *ctx; + + /* Context sid is either set to label or ANY_ASSOC */ + if ((ctx = xfrm->security)) { + if (!selinux_authorizable_ctx(ctx)) + return 0; + + sel_sid = ctx->ctx_sid; + } + + rc = avc_has_perm(fl->secid, sel_sid, SECCLASS_ASSOCIATION, + ASSOCIATION__SENDTO, + NULL)? 0:1; + + return rc; +} + +/* + * LSM hook implementation that determines the sid for the session. + */ + +int selinux_xfrm_decode_session(struct sk_buff *skb, struct flowi *fl) +{ + struct sec_path *sp; + + fl->secid = SECSID_NULL; + + if (skb == NULL) + return 0; + + sp = skb->sp; + if (sp) { + int i, sid_set = 0; + + for (i = sp->len-1; i >= 0; i--) { + struct xfrm_state *x = sp->xvec[i]; + if (selinux_authorizable_xfrm(x)) { + struct xfrm_sec_ctx *ctx = x->security; + + if (!sid_set) { + fl->secid = ctx->ctx_sid; + sid_set = 1; + } + else if (fl->secid != ctx->ctx_sid) + return -EINVAL; + } + } + } + + return 0; +} + /* * Security blob allocation for xfrm_policy and xfrm_state * CTX does not have a meaningful value on input */ -static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp, struct xfrm_user_sec_ctx *uctx) +static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp, + struct xfrm_user_sec_ctx *uctx, struct xfrm_sec_ctx *pol, u32 sid) { int rc = 0; struct task_security_struct *tsec = current->security; - struct xfrm_sec_ctx *ctx; + struct xfrm_sec_ctx *ctx = NULL; + char *ctx_str = NULL; + u32 str_len; + u32 ctx_sid; + + BUG_ON(uctx && pol); + + if (pol) + goto from_policy; BUG_ON(!uctx); - BUG_ON(uctx->ctx_doi != XFRM_SC_ALG_SELINUX); + + if (uctx->ctx_doi != XFRM_SC_ALG_SELINUX) + return -EINVAL; if (uctx->ctx_len >= PAGE_SIZE) return -ENOMEM; @@ -141,9 +248,41 @@ static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp, struct xfrm_us return rc; +from_policy: + BUG_ON(!pol); + rc = security_sid_mls_copy(pol->ctx_sid, sid, &ctx_sid); + if (rc) + goto out; + + rc = security_sid_to_context(ctx_sid, &ctx_str, &str_len); + if (rc) + goto out; + + *ctxp = ctx = kmalloc(sizeof(*ctx) + + str_len, + GFP_ATOMIC); + + if (!ctx) { + rc = -ENOMEM; + goto out; + } + + + ctx->ctx_doi = XFRM_SC_DOI_LSM; + ctx->ctx_alg = XFRM_SC_ALG_SELINUX; + ctx->ctx_sid = ctx_sid; + ctx->ctx_len = str_len; + memcpy(ctx->ctx_str, + ctx_str, + str_len); + + goto out2; + out: *ctxp = NULL; kfree(ctx); +out2: + kfree(ctx_str); return rc; } @@ -157,7 +296,7 @@ int selinux_xfrm_policy_alloc(struct xfrm_policy *xp, struct xfrm_user_sec_ctx * BUG_ON(!xp); - err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx); + err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx, NULL, 0); return err; } @@ -217,13 +356,14 @@ int selinux_xfrm_policy_delete(struct xfrm_policy *xp) * LSM hook implementation that allocs and transfers sec_ctx spec to * xfrm_state. */ -int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx) +int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx, + struct xfrm_sec_ctx *pol, u32 secid) { int err; BUG_ON(!x); - err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx); + err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, pol, secid); return err; } @@ -329,38 +469,30 @@ int selinux_xfrm_state_delete(struct xfrm_state *x) * we need to check for unlabelled access since this may not have * gone thru the IPSec process. */ -int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb) +int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb, + struct avc_audit_data *ad) { int i, rc = 0; struct sec_path *sp; + u32 sel_sid = SECINITSID_UNLABELED; sp = skb->sp; if (sp) { - /* - * __xfrm_policy_check does not approve unless xfrm_policy_ok - * says that spi's match for policy and the socket. - * - * Only need to verify the existence of an authorizable sp. - */ for (i = 0; i < sp->len; i++) { struct xfrm_state *x = sp->xvec[i]; - if (x && selinux_authorizable_xfrm(x)) - goto accept; + if (x && selinux_authorizable_xfrm(x)) { + struct xfrm_sec_ctx *ctx = x->security; + sel_sid = ctx->ctx_sid; + break; + } } } - /* check SELinux sock for unlabelled access */ - rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION, - ASSOCIATION__RECVFROM, NULL); - if (rc) - goto drop; - -accept: - return 0; + rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION, + ASSOCIATION__RECVFROM, ad); -drop: return rc; } @@ -371,7 +503,8 @@ drop: * If we do have a authorizable security association, then it has already been * checked in xfrm_policy_lookup hook. */ -int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb) +int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb, + struct avc_audit_data *ad) { struct dst_entry *dst; int rc = 0; @@ -391,7 +524,7 @@ int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb) } rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION, - ASSOCIATION__SENDTO, NULL); + ASSOCIATION__SENDTO, ad); out: return rc; } -- cgit v1.2.3