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SELinux: Fix SA selection semantics 

Fix the selection of an SA for an outgoing packet to be at the same
context as the originating socket/flow. This eliminates the SELinux
policy's ability to use/sendto SAs with contexts other than the socket's.

With this patch applied, the SELinux policy will require one or more of the
following for a socket to be able to communicate with/without SAs:

1. To enable a socket to communicate without using labeled-IPSec SAs:

allow socket_t unlabeled_t:association { sendto recvfrom }

2. To enable a socket to communicate with labeled-IPSec SAs:

allow socket_t self:association { sendto };
allow socket_t peer_sa_t:association { recvfrom };

Signed-off-by: Venkat Yekkirala <vyekkirala@TrustedCS.com>
Signed-off-by: James Morris <jmorris@namei.org>
hifive-unleashed-5.1
Venkat Yekkirala 2006-11-08 17:04:26 -06:00 committed by David S. Miller
parent 6b877699c6
commit 67f83cbf08
6 changed files with 70 additions and 93 deletions
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19
include/linux/security.h
View File

@ -886,11 +886,6 @@ struct request_sock;
* @xp contains the policy to check for a match.
* @fl contains the flow to check for a match.
* Return 1 if there is a match.
* @xfrm_flow_state_match:
* @fl contains the flow key to match.
* @xfrm points to the xfrm_state to match.
* @xp points to the xfrm_policy to match.
* Return 1 if there is a match.
* @xfrm_decode_session:
* @skb points to skb to decode.
* @secid points to the flow key secid to set.
@ -1388,8 +1383,6 @@ struct security_operations {
int (*xfrm_policy_lookup)(struct xfrm_policy *xp, u32 fl_secid, u8 dir);
int (*xfrm_state_pol_flow_match)(struct xfrm_state *x,
struct xfrm_policy *xp, struct flowi *fl);
int (*xfrm_flow_state_match)(struct flowi *fl, struct xfrm_state *xfrm,
struct xfrm_policy *xp);
int (*xfrm_decode_session)(struct sk_buff *skb, u32 *secid, int ckall);
#endif /* CONFIG_SECURITY_NETWORK_XFRM */
@ -3186,12 +3179,6 @@ static inline int security_xfrm_state_pol_flow_match(struct xfrm_state *x,
return security_ops->xfrm_state_pol_flow_match(x, xp, fl);
}
static inline int security_xfrm_flow_state_match(struct flowi *fl,
struct xfrm_state *xfrm, struct xfrm_policy *xp)
{
return security_ops->xfrm_flow_state_match(fl, xfrm, xp);
}
static inline int security_xfrm_decode_session(struct sk_buff *skb, u32 *secid)
{
return security_ops->xfrm_decode_session(skb, secid, 1);
@ -3255,12 +3242,6 @@ static inline int security_xfrm_state_pol_flow_match(struct xfrm_state *x,
return 1;
}
static inline int security_xfrm_flow_state_match(struct flowi *fl,
struct xfrm_state *xfrm, struct xfrm_policy *xp)
{
return 1;
}
static inline int security_xfrm_decode_session(struct sk_buff *skb, u32 *secid)
{
return 0;

3
net/xfrm/xfrm_policy.c
View File

@ -1894,7 +1894,8 @@ int xfrm_bundle_ok(struct xfrm_policy *pol, struct xfrm_dst *first,
if (fl && !xfrm_selector_match(&dst->xfrm->sel, fl, family))
return 0;
if (fl && !security_xfrm_flow_state_match(fl, dst->xfrm, pol))
if (fl && pol &&
!security_xfrm_state_pol_flow_match(dst->xfrm, pol, fl))
return 0;
if (dst->xfrm->km.state != XFRM_STATE_VALID)
return 0;

7
security/dummy.c
View File

@ -886,12 +886,6 @@ static int dummy_xfrm_state_pol_flow_match(struct xfrm_state *x,
return 1;
}
static int dummy_xfrm_flow_state_match(struct flowi *fl, struct xfrm_state *xfrm,
struct xfrm_policy *xp)
{
return 1;
}
static int dummy_xfrm_decode_session(struct sk_buff *skb, u32 *fl, int ckall)
{
return 0;
@ -1126,7 +1120,6 @@ void security_fixup_ops (struct security_operations *ops)
set_to_dummy_if_null(ops, xfrm_state_delete_security);
set_to_dummy_if_null(ops, xfrm_policy_lookup);
set_to_dummy_if_null(ops, xfrm_state_pol_flow_match);
set_to_dummy_if_null(ops, xfrm_flow_state_match);
set_to_dummy_if_null(ops, xfrm_decode_session);
#endif /* CONFIG_SECURITY_NETWORK_XFRM */
#ifdef CONFIG_KEYS

26
security/selinux/hooks.c
View File

@ -2889,7 +2889,8 @@ static void selinux_task_to_inode(struct task_struct *p,
}
/* Returns error only if unable to parse addresses */
static int selinux_parse_skb_ipv4(struct sk_buff *skb, struct avc_audit_data *ad)
static int selinux_parse_skb_ipv4(struct sk_buff *skb,
struct avc_audit_data *ad, u8 *proto)
{
int offset, ihlen, ret = -EINVAL;
struct iphdr _iph, *ih;
@ -2907,6 +2908,9 @@ static int selinux_parse_skb_ipv4(struct sk_buff *skb, struct avc_audit_data *ad
ad->u.net.v4info.daddr = ih->daddr;
ret = 0;
if (proto)
*proto = ih->protocol;
switch (ih->protocol) {
case IPPROTO_TCP: {
struct tcphdr _tcph, *th;
@ -2950,7 +2954,8 @@ out:
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
/* Returns error only if unable to parse addresses */
static int selinux_parse_skb_ipv6(struct sk_buff *skb, struct avc_audit_data *ad)
static int selinux_parse_skb_ipv6(struct sk_buff *skb,
struct avc_audit_data *ad, u8 *proto)
{
u8 nexthdr;
int ret = -EINVAL, offset;
@ -2971,6 +2976,9 @@ static int selinux_parse_skb_ipv6(struct sk_buff *skb, struct avc_audit_data *ad
if (offset < 0)
goto out;
if (proto)
*proto = nexthdr;
switch (nexthdr) {
case IPPROTO_TCP: {
struct tcphdr _tcph, *th;
@ -3007,13 +3015,13 @@ out:
#endif /* IPV6 */
static int selinux_parse_skb(struct sk_buff *skb, struct avc_audit_data *ad,
char **addrp, int *len, int src)
char **addrp, int *len, int src, u8 *proto)
{
int ret = 0;
switch (ad->u.net.family) {
case PF_INET:
ret = selinux_parse_skb_ipv4(skb, ad);
ret = selinux_parse_skb_ipv4(skb, ad, proto);
if (ret || !addrp)
break;
*len = 4;
@ -3023,7 +3031,7 @@ static int selinux_parse_skb(struct sk_buff *skb, struct avc_audit_data *ad,
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
case PF_INET6:
ret = selinux_parse_skb_ipv6(skb, ad);
ret = selinux_parse_skb_ipv6(skb, ad, proto);
if (ret || !addrp)
break;
*len = 16;
@ -3494,7 +3502,7 @@ static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
ad.u.net.netif = skb->dev ? skb->dev->name : "[unknown]";
ad.u.net.family = family;
err = selinux_parse_skb(skb, &ad, &addrp, &len, 1);
err = selinux_parse_skb(skb, &ad, &addrp, &len, 1, NULL);
if (err)
goto out;
@ -3820,6 +3828,7 @@ static unsigned int selinux_ip_postroute_last(unsigned int hooknum,
struct avc_audit_data ad;
struct net_device *dev = (struct net_device *)out;
struct sk_security_struct *sksec;
u8 proto;
sk = skb->sk;
if (!sk)
@ -3831,7 +3840,7 @@ static unsigned int selinux_ip_postroute_last(unsigned int hooknum,
ad.u.net.netif = dev->name;
ad.u.net.family = family;
err = selinux_parse_skb(skb, &ad, &addrp, &len, 0);
err = selinux_parse_skb(skb, &ad, &addrp, &len, 0, &proto);
if (err)
goto out;
@ -3845,7 +3854,7 @@ static unsigned int selinux_ip_postroute_last(unsigned int hooknum,
if (err)
goto out;
err = selinux_xfrm_postroute_last(sksec->sid, skb, &ad);
err = selinux_xfrm_postroute_last(sksec->sid, skb, &ad, proto);
out:
return err ? NF_DROP : NF_ACCEPT;
}
@ -4764,7 +4773,6 @@ static struct security_operations selinux_ops = {
.xfrm_state_delete_security = selinux_xfrm_state_delete,
.xfrm_policy_lookup = selinux_xfrm_policy_lookup,
.xfrm_state_pol_flow_match = selinux_xfrm_state_pol_flow_match,
.xfrm_flow_state_match = selinux_xfrm_flow_state_match,
.xfrm_decode_session = selinux_xfrm_decode_session,
#endif

7
security/selinux/include/xfrm.h
View File

@ -19,9 +19,6 @@ int selinux_xfrm_state_delete(struct xfrm_state *x);
int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir);
int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x,
struct xfrm_policy *xp, struct flowi *fl);
int selinux_xfrm_flow_state_match(struct flowi *fl, struct xfrm_state *xfrm,
struct xfrm_policy *xp);
/*
* Extract the security blob from the sock (it's actually on the socket)
@ -38,7 +35,7 @@ static inline struct inode_security_struct *get_sock_isec(struct sock *sk)
int selinux_xfrm_sock_rcv_skb(u32 sid, struct sk_buff *skb,
struct avc_audit_data *ad);
int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
struct avc_audit_data *ad);
struct avc_audit_data *ad, u8 proto);
u32 selinux_socket_getpeer_dgram(struct sk_buff *skb);
int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall);
#else
@ -49,7 +46,7 @@ static inline int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
}
static inline int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
struct avc_audit_data *ad)
struct avc_audit_data *ad, u8 proto)
{
return 0;
}

101
security/selinux/xfrm.c
View File

@ -115,70 +115,39 @@ int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *
struct flowi *fl)
{
u32 state_sid;
u32 pol_sid;
int err;
int rc;
if (xp->security) {
if (!x->security)
/* unlabeled SA and labeled policy can't match */
return 0;
else
state_sid = x->security->ctx_sid;
pol_sid = xp->security->ctx_sid;
} else
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;
err = avc_has_perm(state_sid, pol_sid, SECCLASS_ASSOCIATION,
ASSOCIATION__POLMATCH,
NULL);
state_sid = x->security->ctx_sid;
if (err)
if (fl->secid != state_sid)
return 0;
err = avc_has_perm(fl->secid, state_sid, SECCLASS_ASSOCIATION,
rc = avc_has_perm(fl->secid, state_sid, SECCLASS_ASSOCIATION,
ASSOCIATION__SENDTO,
NULL)? 0:1;
return err;
}
/*
* 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,
struct xfrm_policy *xp)
{
int rc = 0;
u32 sel_sid = SECINITSID_UNLABELED;
struct xfrm_sec_ctx *ctx;
if (!xp->security)
if (!xfrm->security)
return 1;
else
return 0;
else
if (!xfrm->security)
return 0;
/* 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;
/*
* 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;
}
@ -481,6 +450,13 @@ int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
}
}
/*
* 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);
@ -492,10 +468,10 @@ int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
* 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.
* 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)
struct avc_audit_data *ad, u8 proto)
{
struct dst_entry *dst;
int rc = 0;
@ -514,6 +490,27 @@ int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
}
}
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: