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https://mirrors.bfsu.edu.cn/git/linux.git
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adf30907d6
Define three accessors to get/set dst attached to a skb struct dst_entry *skb_dst(const struct sk_buff *skb) void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst) void skb_dst_drop(struct sk_buff *skb) This one should replace occurrences of : dst_release(skb->dst) skb->dst = NULL; Delete skb->dst field Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
490 lines
11 KiB
C
490 lines
11 KiB
C
/*
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* NSA Security-Enhanced Linux (SELinux) security module
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*
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* This file contains the SELinux XFRM hook function implementations.
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*
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* Authors: Serge Hallyn <sergeh@us.ibm.com>
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* Trent Jaeger <jaegert@us.ibm.com>
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*
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* Updated: Venkat Yekkirala <vyekkirala@TrustedCS.com>
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*
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* Granular IPSec Associations for use in MLS environments.
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*
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* Copyright (C) 2005 International Business Machines Corporation
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* Copyright (C) 2006 Trusted Computer Solutions, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2,
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* as published by the Free Software Foundation.
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*/
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/*
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* USAGE:
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* NOTES:
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* 1. Make sure to enable the following options in your kernel config:
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* CONFIG_SECURITY=y
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* CONFIG_SECURITY_NETWORK=y
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* CONFIG_SECURITY_NETWORK_XFRM=y
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* CONFIG_SECURITY_SELINUX=m/y
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* ISSUES:
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* 1. Caching packets, so they are not dropped during negotiation
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* 2. Emulating a reasonable SO_PEERSEC across machines
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* 3. Testing addition of sk_policy's with security context via setsockopt
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/security.h>
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#include <linux/types.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter_ipv6.h>
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#include <linux/ip.h>
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#include <linux/tcp.h>
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#include <linux/skbuff.h>
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#include <linux/xfrm.h>
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#include <net/xfrm.h>
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#include <net/checksum.h>
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#include <net/udp.h>
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#include <asm/atomic.h>
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#include "avc.h"
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#include "objsec.h"
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#include "xfrm.h"
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/* Labeled XFRM instance counter */
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atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0);
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/*
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* Returns true if an LSM/SELinux context
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*/
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static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx *ctx)
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{
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return (ctx &&
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(ctx->ctx_doi == XFRM_SC_DOI_LSM) &&
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(ctx->ctx_alg == XFRM_SC_ALG_SELINUX));
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}
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/*
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* Returns true if the xfrm contains a security blob for SELinux
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*/
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static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
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{
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return selinux_authorizable_ctx(x->security);
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}
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/*
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* LSM hook implementation that authorizes that a flow can use
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* a xfrm policy rule.
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*/
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int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir)
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{
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int rc;
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u32 sel_sid;
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/* Context sid is either set to label or ANY_ASSOC */
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if (ctx) {
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if (!selinux_authorizable_ctx(ctx))
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return -EINVAL;
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sel_sid = ctx->ctx_sid;
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} else
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/*
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* All flows should be treated as polmatch'ing an
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* otherwise applicable "non-labeled" policy. This
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* would prevent inadvertent "leaks".
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*/
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return 0;
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rc = avc_has_perm(fl_secid, sel_sid, SECCLASS_ASSOCIATION,
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ASSOCIATION__POLMATCH,
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NULL);
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if (rc == -EACCES)
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return -ESRCH;
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return rc;
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}
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/*
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* LSM hook implementation that authorizes that a state matches
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* the given policy, flow combo.
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*/
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int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *xp,
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struct flowi *fl)
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{
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u32 state_sid;
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int rc;
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if (!xp->security)
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if (x->security)
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/* unlabeled policy and labeled SA can't match */
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return 0;
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else
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/* unlabeled policy and unlabeled SA match all flows */
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return 1;
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else
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if (!x->security)
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/* unlabeled SA and labeled policy can't match */
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return 0;
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else
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if (!selinux_authorizable_xfrm(x))
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/* Not a SELinux-labeled SA */
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return 0;
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state_sid = x->security->ctx_sid;
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if (fl->secid != state_sid)
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return 0;
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rc = avc_has_perm(fl->secid, state_sid, SECCLASS_ASSOCIATION,
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ASSOCIATION__SENDTO,
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NULL)? 0:1;
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/*
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* We don't need a separate SA Vs. policy polmatch check
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* since the SA is now of the same label as the flow and
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* a flow Vs. policy polmatch check had already happened
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* in selinux_xfrm_policy_lookup() above.
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*/
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return rc;
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}
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/*
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* LSM hook implementation that checks and/or returns the xfrm sid for the
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* incoming packet.
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*/
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int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
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{
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struct sec_path *sp;
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*sid = SECSID_NULL;
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if (skb == NULL)
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return 0;
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sp = skb->sp;
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if (sp) {
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int i, sid_set = 0;
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for (i = sp->len-1; i >= 0; i--) {
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struct xfrm_state *x = sp->xvec[i];
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if (selinux_authorizable_xfrm(x)) {
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struct xfrm_sec_ctx *ctx = x->security;
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if (!sid_set) {
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*sid = ctx->ctx_sid;
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sid_set = 1;
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if (!ckall)
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break;
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} else if (*sid != ctx->ctx_sid)
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return -EINVAL;
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}
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}
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}
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return 0;
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}
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/*
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* Security blob allocation for xfrm_policy and xfrm_state
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* CTX does not have a meaningful value on input
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*/
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static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp,
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struct xfrm_user_sec_ctx *uctx, u32 sid)
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{
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int rc = 0;
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const struct task_security_struct *tsec = current_security();
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struct xfrm_sec_ctx *ctx = NULL;
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char *ctx_str = NULL;
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u32 str_len;
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BUG_ON(uctx && sid);
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if (!uctx)
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goto not_from_user;
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if (uctx->ctx_doi != XFRM_SC_ALG_SELINUX)
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return -EINVAL;
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str_len = uctx->ctx_len;
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if (str_len >= PAGE_SIZE)
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return -ENOMEM;
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*ctxp = ctx = kmalloc(sizeof(*ctx) +
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str_len + 1,
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GFP_KERNEL);
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if (!ctx)
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return -ENOMEM;
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ctx->ctx_doi = uctx->ctx_doi;
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ctx->ctx_len = str_len;
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ctx->ctx_alg = uctx->ctx_alg;
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memcpy(ctx->ctx_str,
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uctx+1,
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str_len);
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ctx->ctx_str[str_len] = 0;
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rc = security_context_to_sid(ctx->ctx_str,
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str_len,
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&ctx->ctx_sid);
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if (rc)
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goto out;
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/*
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* Does the subject have permission to set security context?
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*/
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rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
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SECCLASS_ASSOCIATION,
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ASSOCIATION__SETCONTEXT, NULL);
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if (rc)
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goto out;
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return rc;
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not_from_user:
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rc = security_sid_to_context(sid, &ctx_str, &str_len);
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if (rc)
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goto out;
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*ctxp = ctx = kmalloc(sizeof(*ctx) +
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str_len,
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GFP_ATOMIC);
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if (!ctx) {
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rc = -ENOMEM;
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goto out;
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}
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ctx->ctx_doi = XFRM_SC_DOI_LSM;
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ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
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ctx->ctx_sid = sid;
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ctx->ctx_len = str_len;
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memcpy(ctx->ctx_str,
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ctx_str,
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str_len);
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goto out2;
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out:
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*ctxp = NULL;
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kfree(ctx);
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out2:
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kfree(ctx_str);
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return rc;
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}
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/*
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* LSM hook implementation that allocs and transfers uctx spec to
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* xfrm_policy.
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*/
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int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
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struct xfrm_user_sec_ctx *uctx)
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{
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int err;
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BUG_ON(!uctx);
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err = selinux_xfrm_sec_ctx_alloc(ctxp, uctx, 0);
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if (err == 0)
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atomic_inc(&selinux_xfrm_refcount);
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return err;
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}
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/*
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* LSM hook implementation that copies security data structure from old to
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* new for policy cloning.
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*/
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int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
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struct xfrm_sec_ctx **new_ctxp)
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{
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struct xfrm_sec_ctx *new_ctx;
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if (old_ctx) {
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new_ctx = kmalloc(sizeof(*old_ctx) + old_ctx->ctx_len,
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GFP_KERNEL);
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if (!new_ctx)
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return -ENOMEM;
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memcpy(new_ctx, old_ctx, sizeof(*new_ctx));
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memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len);
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*new_ctxp = new_ctx;
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}
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return 0;
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}
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/*
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* LSM hook implementation that frees xfrm_sec_ctx security information.
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*/
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void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
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{
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kfree(ctx);
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}
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/*
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* LSM hook implementation that authorizes deletion of labeled policies.
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*/
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int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
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{
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const struct task_security_struct *tsec = current_security();
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int rc = 0;
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if (ctx) {
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rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
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SECCLASS_ASSOCIATION,
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ASSOCIATION__SETCONTEXT, NULL);
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if (rc == 0)
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atomic_dec(&selinux_xfrm_refcount);
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}
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return rc;
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}
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/*
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* LSM hook implementation that allocs and transfers sec_ctx spec to
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* xfrm_state.
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*/
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int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx,
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u32 secid)
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{
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int err;
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BUG_ON(!x);
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err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, secid);
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if (err == 0)
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atomic_inc(&selinux_xfrm_refcount);
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return err;
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}
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/*
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* LSM hook implementation that frees xfrm_state security information.
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*/
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void selinux_xfrm_state_free(struct xfrm_state *x)
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{
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struct xfrm_sec_ctx *ctx = x->security;
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kfree(ctx);
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}
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/*
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* LSM hook implementation that authorizes deletion of labeled SAs.
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*/
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int selinux_xfrm_state_delete(struct xfrm_state *x)
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{
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const struct task_security_struct *tsec = current_security();
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struct xfrm_sec_ctx *ctx = x->security;
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int rc = 0;
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if (ctx) {
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rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
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SECCLASS_ASSOCIATION,
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ASSOCIATION__SETCONTEXT, NULL);
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if (rc == 0)
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atomic_dec(&selinux_xfrm_refcount);
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}
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return rc;
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}
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/*
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* LSM hook that controls access to unlabelled packets. If
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* a xfrm_state is authorizable (defined by macro) then it was
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* already authorized by the IPSec process. If not, then
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* we need to check for unlabelled access since this may not have
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* gone thru the IPSec process.
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*/
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int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
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struct avc_audit_data *ad)
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{
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int i, rc = 0;
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struct sec_path *sp;
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u32 sel_sid = SECINITSID_UNLABELED;
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sp = skb->sp;
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if (sp) {
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for (i = 0; i < sp->len; i++) {
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struct xfrm_state *x = sp->xvec[i];
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if (x && selinux_authorizable_xfrm(x)) {
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struct xfrm_sec_ctx *ctx = x->security;
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sel_sid = ctx->ctx_sid;
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break;
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}
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}
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}
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/*
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* This check even when there's no association involved is
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* intended, according to Trent Jaeger, to make sure a
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* process can't engage in non-ipsec communication unless
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* explicitly allowed by policy.
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*/
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rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION,
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ASSOCIATION__RECVFROM, ad);
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return rc;
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}
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/*
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* POSTROUTE_LAST hook's XFRM processing:
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* If we have no security association, then we need to determine
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* whether the socket is allowed to send to an unlabelled destination.
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* If we do have a authorizable security association, then it has already been
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* checked in the selinux_xfrm_state_pol_flow_match hook above.
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*/
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int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
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struct avc_audit_data *ad, u8 proto)
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{
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struct dst_entry *dst;
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int rc = 0;
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dst = skb_dst(skb);
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if (dst) {
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struct dst_entry *dst_test;
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for (dst_test = dst; dst_test != NULL;
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dst_test = dst_test->child) {
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struct xfrm_state *x = dst_test->xfrm;
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if (x && selinux_authorizable_xfrm(x))
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goto out;
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}
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}
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switch (proto) {
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case IPPROTO_AH:
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case IPPROTO_ESP:
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case IPPROTO_COMP:
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/*
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* We should have already seen this packet once before
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* it underwent xfrm(s). No need to subject it to the
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* unlabeled check.
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*/
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goto out;
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default:
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break;
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}
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/*
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* This check even when there's no association involved is
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* intended, according to Trent Jaeger, to make sure a
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* process can't engage in non-ipsec communication unless
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* explicitly allowed by policy.
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*/
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rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION,
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ASSOCIATION__SENDTO, ad);
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out:
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return rc;
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}
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