--- /dev/null
+/*
+ * NSA Security-Enhanced Linux (SELinux) security module
+ *
+ * This file contains the SELinux XFRM hook function implementations.
+ *
+ * Authors: Serge Hallyn <sergeh@us.ibm.com>
+ * Trent Jaeger <jaegert@us.ibm.com>
+ *
+ * Copyright (C) 2005 International Business Machines Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2,
+ * as published by the Free Software Foundation.
+ */
+
+/*
+ * USAGE:
+ * NOTES:
+ * 1. Make sure to enable the following options in your kernel config:
+ * CONFIG_SECURITY=y
+ * CONFIG_SECURITY_NETWORK=y
+ * CONFIG_SECURITY_NETWORK_XFRM=y
+ * CONFIG_SECURITY_SELINUX=m/y
+ * ISSUES:
+ * 1. Caching packets, so they are not dropped during negotiation
+ * 2. Emulating a reasonable SO_PEERSEC across machines
+ * 3. Testing addition of sk_policy's with security context via setsockopt
+ */
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/security.h>
+#include <linux/types.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/ip.h>
+#include <linux/tcp.h>
+#include <linux/skbuff.h>
+#include <linux/xfrm.h>
+#include <net/xfrm.h>
+#include <net/checksum.h>
+#include <net/udp.h>
+#include <asm/semaphore.h>
+
+#include "avc.h"
+#include "objsec.h"
+#include "xfrm.h"
+
+
+/*
+ * Returns true if an LSM/SELinux context
+ */
+static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx *ctx)
+{
+ return (ctx &&
+ (ctx->ctx_doi == XFRM_SC_DOI_LSM) &&
+ (ctx->ctx_alg == XFRM_SC_ALG_SELINUX));
+}
+
+/*
+ * Returns true if the xfrm contains a security blob for SELinux
+ */
+static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
+{
+ return selinux_authorizable_ctx(x->security);
+}
+
+/*
+ * LSM hook implementation that authorizes that a socket can be used
+ * with the corresponding xfrm_sec_ctx and direction.
+ */
+int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 sk_sid, u8 dir)
+{
+ 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 = xp->security)) {
+ if (!selinux_authorizable_ctx(ctx))
+ return -EINVAL;
+
+ 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))),
+ NULL);
+
+ return rc;
+}
+
+/*
+ * 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)
+{
+ int rc = 0;
+ struct task_security_struct *tsec = current->security;
+ struct xfrm_sec_ctx *ctx;
+
+ BUG_ON(!uctx);
+ BUG_ON(uctx->ctx_doi != XFRM_SC_ALG_SELINUX);
+
+ if (uctx->ctx_len >= PAGE_SIZE)
+ return -ENOMEM;
+
+ *ctxp = ctx = kmalloc(sizeof(*ctx) +
+ uctx->ctx_len,
+ GFP_KERNEL);
+
+ if (!ctx)
+ return -ENOMEM;
+
+ ctx->ctx_doi = uctx->ctx_doi;
+ ctx->ctx_len = uctx->ctx_len;
+ ctx->ctx_alg = uctx->ctx_alg;
+
+ memcpy(ctx->ctx_str,
+ uctx+1,
+ ctx->ctx_len);
+ rc = security_context_to_sid(ctx->ctx_str,
+ ctx->ctx_len,
+ &ctx->ctx_sid);
+
+ if (rc)
+ goto out;
+
+ /*
+ * Does the subject have permission to set security or permission to
+ * do the relabel?
+ * Must be permitted to relabel from default socket type (process type)
+ * to specified context
+ */
+ rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
+ SECCLASS_ASSOCIATION,
+ ASSOCIATION__SETCONTEXT, NULL);
+ if (rc)
+ goto out;
+
+ return rc;
+
+out:
+ *ctxp = NULL;
+ kfree(ctx);
+ return rc;
+}
+
+/*
+ * LSM hook implementation that allocs and transfers uctx spec to
+ * xfrm_policy.
+ */
+int selinux_xfrm_policy_alloc(struct xfrm_policy *xp, struct xfrm_user_sec_ctx *uctx)
+{
+ int err;
+
+ BUG_ON(!xp);
+
+ err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx);
+ return err;
+}
+
+
+/*
+ * LSM hook implementation that copies security data structure from old to
+ * new for policy cloning.
+ */
+int selinux_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new)
+{
+ struct xfrm_sec_ctx *old_ctx, *new_ctx;
+
+ old_ctx = old->security;
+
+ if (old_ctx) {
+ new_ctx = new->security = kmalloc(sizeof(*new_ctx) +
+ old_ctx->ctx_len,
+ GFP_KERNEL);
+
+ if (!new_ctx)
+ return -ENOMEM;
+
+ memcpy(new_ctx, old_ctx, sizeof(*new_ctx));
+ memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len);
+ }
+ return 0;
+}
+
+/*
+ * LSM hook implementation that frees xfrm_policy security information.
+ */
+void selinux_xfrm_policy_free(struct xfrm_policy *xp)
+{
+ struct xfrm_sec_ctx *ctx = xp->security;
+ if (ctx)
+ kfree(ctx);
+}
+
+/*
+ * 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 err;
+
+ BUG_ON(!x);
+
+ err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx);
+ return err;
+}
+
+/*
+ * LSM hook implementation that frees xfrm_state security information.
+ */
+void selinux_xfrm_state_free(struct xfrm_state *x)
+{
+ struct xfrm_sec_ctx *ctx = x->security;
+ if (ctx)
+ kfree(ctx);
+}
+
+/*
+ * SELinux internal function to retrieve the context of a connected
+ * (sk->sk_state == TCP_ESTABLISHED) TCP socket based on its security
+ * association used to connect to the remote socket.
+ *
+ * Retrieve via getsockopt SO_PEERSEC.
+ */
+u32 selinux_socket_getpeer_stream(struct sock *sk)
+{
+ struct dst_entry *dst, *dst_test;
+ u32 peer_sid = SECSID_NULL;
+
+ if (sk->sk_state != TCP_ESTABLISHED)
+ goto out;
+
+ dst = sk_dst_get(sk);
+ if (!dst)
+ goto out;
+
+ for (dst_test = dst; dst_test != 0;
+ dst_test = dst_test->child) {
+ struct xfrm_state *x = dst_test->xfrm;
+
+ if (x && selinux_authorizable_xfrm(x)) {
+ struct xfrm_sec_ctx *ctx = x->security;
+ peer_sid = ctx->ctx_sid;
+ break;
+ }
+ }
+ dst_release(dst);
+
+out:
+ return peer_sid;
+}
+
+/*
+ * SELinux internal function to retrieve the context of a UDP packet
+ * based on its security association used to connect to the remote socket.
+ *
+ * Retrieve via setsockopt IP_PASSSEC and recvmsg with control message
+ * type SCM_SECURITY.
+ */
+u32 selinux_socket_getpeer_dgram(struct sk_buff *skb)
+{
+ struct sec_path *sp;
+
+ if (skb == NULL)
+ return SECSID_NULL;
+
+ if (skb->sk->sk_protocol != IPPROTO_UDP)
+ return SECSID_NULL;
+
+ sp = skb->sp;
+ if (sp) {
+ int i;
+
+ 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;
+ return ctx->ctx_sid;
+ }
+ }
+ }
+
+ return SECSID_NULL;
+}
+
+/*
+ * LSM hook that controls access to unlabelled packets. If
+ * a xfrm_state is authorizable (defined by macro) then it was
+ * already authorized by the IPSec process. If not, then
+ * 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 i, rc = 0;
+ struct sec_path *sp;
+
+ 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;
+ }
+ }
+
+ /* 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;
+
+drop:
+ return rc;
+}
+
+/*
+ * POSTROUTE_LAST hook's XFRM processing:
+ * 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.
+ */
+int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb)
+{
+ struct dst_entry *dst;
+ int rc = 0;
+
+ dst = skb->dst;
+
+ if (dst) {
+ struct dst_entry *dst_test;
+
+ for (dst_test = dst; dst_test != 0;
+ dst_test = dst_test->child) {
+ struct xfrm_state *x = dst_test->xfrm;
+
+ if (x && selinux_authorizable_xfrm(x))
+ goto accept;
+ }
+ }
+
+ rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION,
+ ASSOCIATION__SENDTO, NULL);
+ if (rc)
+ goto drop;
+
+accept:
+ return NF_ACCEPT;
+
+drop:
+ return NF_DROP;
+}
git://git.onelab.eu / linux-2.6.git / blobdiff