| /* |
| * 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> |
| * |
| * Updated: Venkat Yekkirala <vyekkirala@TrustedCS.com> |
| * |
| * 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, |
| * 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/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/atomic.h> |
| |
| #include "avc.h" |
| #include "objsec.h" |
| #include "xfrm.h" |
| |
| /* Labeled XFRM instance counter */ |
| atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0); |
| |
| /* |
| * 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 flow can use |
| * a xfrm policy rule. |
| */ |
| int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir) |
| { |
| int rc; |
| u32 sel_sid; |
| |
| /* Context sid is either set to label or ANY_ASSOC */ |
| if (ctx) { |
| if (!selinux_authorizable_ctx(ctx)) |
| return -EINVAL; |
| |
| sel_sid = ctx->ctx_sid; |
| } else |
| /* |
| * All flows should be treated as polmatch'ing an |
| * otherwise applicable "non-labeled" policy. This |
| * would prevent inadvertent "leaks". |
| */ |
| return 0; |
| |
| rc = avc_has_perm(fl_secid, sel_sid, SECCLASS_ASSOCIATION, |
| ASSOCIATION__POLMATCH, |
| NULL); |
| |
| if (rc == -EACCES) |
| return -ESRCH; |
| |
| 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; |
| int rc; |
| |
| 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; |
| else |
| 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; |
| |
| state_sid = x->security->ctx_sid; |
| |
| if (fl->secid != state_sid) |
| return 0; |
| |
| 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; |
| } |
| |
| /* |
| * LSM hook implementation that checks and/or returns the xfrm sid for the |
| * incoming packet. |
| */ |
| |
| int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall) |
| { |
| struct sec_path *sp; |
| |
| *sid = 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) { |
| *sid = ctx->ctx_sid; |
| sid_set = 1; |
| |
| if (!ckall) |
| break; |
| } else if (*sid != 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, u32 sid) |
| { |
| int rc = 0; |
| const struct task_security_struct *tsec = current_security(); |
| struct xfrm_sec_ctx *ctx = NULL; |
| char *ctx_str = NULL; |
| u32 str_len; |
| |
| BUG_ON(uctx && sid); |
| |
| if (!uctx) |
| goto not_from_user; |
| |
| if (uctx->ctx_doi != XFRM_SC_ALG_SELINUX) |
| return -EINVAL; |
| |
| str_len = uctx->ctx_len; |
| if (str_len >= PAGE_SIZE) |
| return -ENOMEM; |
| |
| *ctxp = ctx = kmalloc(sizeof(*ctx) + |
| str_len + 1, |
| GFP_KERNEL); |
| |
| if (!ctx) |
| return -ENOMEM; |
| |
| ctx->ctx_doi = uctx->ctx_doi; |
| ctx->ctx_len = str_len; |
| ctx->ctx_alg = uctx->ctx_alg; |
| |
| memcpy(ctx->ctx_str, |
| uctx+1, |
| str_len); |
| ctx->ctx_str[str_len] = 0; |
| rc = security_context_to_sid(ctx->ctx_str, |
| str_len, |
| &ctx->ctx_sid); |
| |
| if (rc) |
| goto out; |
| |
| /* |
| * Does the subject have permission to set security context? |
| */ |
| rc = avc_has_perm(tsec->sid, ctx->ctx_sid, |
| SECCLASS_ASSOCIATION, |
| ASSOCIATION__SETCONTEXT, NULL); |
| if (rc) |
| goto out; |
| |
| return rc; |
| |
| not_from_user: |
| rc = security_sid_to_context(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 = 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; |
| } |
| |
| /* |
| * LSM hook implementation that allocs and transfers uctx spec to |
| * xfrm_policy. |
| */ |
| int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp, |
| struct xfrm_user_sec_ctx *uctx) |
| { |
| int err; |
| |
| BUG_ON(!uctx); |
| |
| err = selinux_xfrm_sec_ctx_alloc(ctxp, uctx, 0); |
| if (err == 0) |
| atomic_inc(&selinux_xfrm_refcount); |
| |
| return err; |
| } |
| |
| |
| /* |
| * LSM hook implementation that copies security data structure from old to |
| * new for policy cloning. |
| */ |
| int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx, |
| struct xfrm_sec_ctx **new_ctxp) |
| { |
| struct xfrm_sec_ctx *new_ctx; |
| |
| if (old_ctx) { |
| new_ctx = kmalloc(sizeof(*old_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); |
| *new_ctxp = new_ctx; |
| } |
| return 0; |
| } |
| |
| /* |
| * LSM hook implementation that frees xfrm_sec_ctx security information. |
| */ |
| void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx) |
| { |
| kfree(ctx); |
| } |
| |
| /* |
| * LSM hook implementation that authorizes deletion of labeled policies. |
| */ |
| int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx) |
| { |
| const struct task_security_struct *tsec = current_security(); |
| int rc = 0; |
| |
| if (ctx) { |
| rc = avc_has_perm(tsec->sid, ctx->ctx_sid, |
| SECCLASS_ASSOCIATION, |
| ASSOCIATION__SETCONTEXT, NULL); |
| if (rc == 0) |
| atomic_dec(&selinux_xfrm_refcount); |
| } |
| |
| return rc; |
| } |
| |
| /* |
| * 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, |
| u32 secid) |
| { |
| int err; |
| |
| BUG_ON(!x); |
| |
| err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, secid); |
| if (err == 0) |
| atomic_inc(&selinux_xfrm_refcount); |
| 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; |
| kfree(ctx); |
| } |
| |
| /* |
| * LSM hook implementation that authorizes deletion of labeled SAs. |
| */ |
| int selinux_xfrm_state_delete(struct xfrm_state *x) |
| { |
| const struct task_security_struct *tsec = current_security(); |
| struct xfrm_sec_ctx *ctx = x->security; |
| int rc = 0; |
| |
| if (ctx) { |
| rc = avc_has_perm(tsec->sid, ctx->ctx_sid, |
| SECCLASS_ASSOCIATION, |
| ASSOCIATION__SETCONTEXT, NULL); |
| if (rc == 0) |
| atomic_dec(&selinux_xfrm_refcount); |
| } |
| |
| return rc; |
| } |
| |
| /* |
| * 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, |
| struct avc_audit_data *ad) |
| { |
| int i, rc = 0; |
| struct sec_path *sp; |
| u32 sel_sid = SECINITSID_UNLABELED; |
| |
| sp = skb->sp; |
| |
| if (sp) { |
| for (i = 0; i < sp->len; i++) { |
| struct xfrm_state *x = sp->xvec[i]; |
| |
| if (x && selinux_authorizable_xfrm(x)) { |
| struct xfrm_sec_ctx *ctx = x->security; |
| sel_sid = ctx->ctx_sid; |
| 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, sel_sid, SECCLASS_ASSOCIATION, |
| ASSOCIATION__RECVFROM, ad); |
| |
| 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 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, u8 proto) |
| { |
| struct dst_entry *dst; |
| int rc = 0; |
| |
| dst = skb->dst; |
| |
| if (dst) { |
| struct dst_entry *dst_test; |
| |
| for (dst_test = dst; dst_test != NULL; |
| dst_test = dst_test->child) { |
| struct xfrm_state *x = dst_test->xfrm; |
| |
| if (x && selinux_authorizable_xfrm(x)) |
| goto out; |
| } |
| } |
| |
| 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: |
| return rc; |
| } |