diff options
Diffstat (limited to 'ANDROID_3.4.5/security/selinux/xfrm.c')
-rw-r--r-- | ANDROID_3.4.5/security/selinux/xfrm.c | 490 |
1 files changed, 490 insertions, 0 deletions
diff --git a/ANDROID_3.4.5/security/selinux/xfrm.c b/ANDROID_3.4.5/security/selinux/xfrm.c new file mode 100644 index 00000000..48665ecd --- /dev/null +++ b/ANDROID_3.4.5/security/selinux/xfrm.c @@ -0,0 +1,490 @@ +/* + * 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/slab.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 <linux/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, + const 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->flowi_secid != state_sid) + return 0; + + rc = avc_has_perm(fl->flowi_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_alg != 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 common_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 common_audit_data *ad, u8 proto) +{ + struct dst_entry *dst; + int rc = 0; + + dst = skb_dst(skb); + + 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; +} |