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authorVenkat Yekkirala <vyekkirala@trustedcs.com>2006-10-05 16:42:18 -0400
committerDavid S. Miller <davem@sunset.davemloft.net>2006-10-12 02:59:37 -0400
commit5b368e61c2bcb2666bb66e2acf1d6d85ba6f474d (patch)
tree293f595f737540a546ba186ba1f054389aa95f6f /security/selinux
parent134b0fc544ba062498451611cb6f3e4454221b3d (diff)
IPsec: correct semantics for SELinux policy matching
Currently when an IPSec policy rule doesn't specify a security context, it is assumed to be "unlabeled" by SELinux, and so the IPSec policy rule fails to match to a flow that it would otherwise match to, unless one has explicitly added an SELinux policy rule allowing the flow to "polmatch" to the "unlabeled" IPSec policy rules. In the absence of such an explicitly added SELinux policy rule, the IPSec policy rule fails to match and so the packet(s) flow in clear text without the otherwise applicable xfrm(s) applied. The above SELinux behavior violates the SELinux security notion of "deny by default" which should actually translate to "encrypt by default" in the above case. This was first reported by Evgeniy Polyakov and the way James Morris was seeing the problem was when connecting via IPsec to a confined service on an SELinux box (vsftpd), which did not have the appropriate SELinux policy permissions to send packets via IPsec. With this patch applied, SELinux "polmatching" of flows Vs. IPSec policy rules will only come into play when there's a explicit context specified for the IPSec policy rule (which also means there's corresponding SELinux policy allowing appropriate domains/flows to polmatch to this context). Secondly, when a security module is loaded (in this case, SELinux), the security_xfrm_policy_lookup() hook can return errors other than access denied, such as -EINVAL. We were not handling that correctly, and in fact inverting the return logic and propagating a false "ok" back up to xfrm_lookup(), which then allowed packets to pass as if they were not associated with an xfrm policy. The solution for this is to first ensure that errno values are correctly propagated all the way back up through the various call chains from security_xfrm_policy_lookup(), and handled correctly. Then, flow_cache_lookup() is modified, so that if the policy resolver fails (typically a permission denied via the security module), the flow cache entry is killed rather than having a null policy assigned (which indicates that the packet can pass freely). This also forces any future lookups for the same flow to consult the security module (e.g. SELinux) for current security policy (rather than, say, caching the error on the flow cache entry). This patch: Fix the selinux side of things. This makes sure SELinux polmatching of flow contexts to IPSec policy rules comes into play only when an explicit context is associated with the IPSec policy rule. Also, this no longer defaults the context of a socket policy to the context of the socket since the "no explicit context" case is now handled properly. Signed-off-by: Venkat Yekkirala <vyekkirala@TrustedCS.com> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'security/selinux')
-rw-r--r--security/selinux/include/xfrm.h3
-rw-r--r--security/selinux/xfrm.c53
2 files changed, 43 insertions, 13 deletions
diff --git a/security/selinux/include/xfrm.h b/security/selinux/include/xfrm.h
index 81eb59890162..526b28019aca 100644
--- a/security/selinux/include/xfrm.h
+++ b/security/selinux/include/xfrm.h
@@ -19,7 +19,8 @@ int selinux_xfrm_state_delete(struct xfrm_state *x);
19int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir); 19int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir);
20int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, 20int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x,
21 struct xfrm_policy *xp, struct flowi *fl); 21 struct xfrm_policy *xp, struct flowi *fl);
22int selinux_xfrm_flow_state_match(struct flowi *fl, struct xfrm_state *xfrm); 22int selinux_xfrm_flow_state_match(struct flowi *fl, struct xfrm_state *xfrm,
23 struct xfrm_policy *xp);
23 24
24 25
25/* 26/*
diff --git a/security/selinux/xfrm.c b/security/selinux/xfrm.c
index 3e742b850af6..675b995a67c3 100644
--- a/security/selinux/xfrm.c
+++ b/security/selinux/xfrm.c
@@ -77,8 +77,8 @@ static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
77 */ 77 */
78int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir) 78int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir)
79{ 79{
80 int rc = 0; 80 int rc;
81 u32 sel_sid = SECINITSID_UNLABELED; 81 u32 sel_sid;
82 struct xfrm_sec_ctx *ctx; 82 struct xfrm_sec_ctx *ctx;
83 83
84 /* Context sid is either set to label or ANY_ASSOC */ 84 /* Context sid is either set to label or ANY_ASSOC */
@@ -88,11 +88,21 @@ int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir)
88 88
89 sel_sid = ctx->ctx_sid; 89 sel_sid = ctx->ctx_sid;
90 } 90 }
91 else
92 /*
93 * All flows should be treated as polmatch'ing an
94 * otherwise applicable "non-labeled" policy. This
95 * would prevent inadvertent "leaks".
96 */
97 return 0;
91 98
92 rc = avc_has_perm(fl_secid, sel_sid, SECCLASS_ASSOCIATION, 99 rc = avc_has_perm(fl_secid, sel_sid, SECCLASS_ASSOCIATION,
93 ASSOCIATION__POLMATCH, 100 ASSOCIATION__POLMATCH,
94 NULL); 101 NULL);
95 102
103 if (rc == -EACCES)
104 rc = -ESRCH;
105
96 return rc; 106 return rc;
97} 107}
98 108
@@ -108,15 +118,20 @@ int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *
108 u32 pol_sid; 118 u32 pol_sid;
109 int err; 119 int err;
110 120
111 if (x->security) 121 if (xp->security) {
112 state_sid = x->security->ctx_sid; 122 if (!x->security)
113 else 123 /* unlabeled SA and labeled policy can't match */
114 state_sid = SECINITSID_UNLABELED; 124 return 0;
115 125 else
116 if (xp->security) 126 state_sid = x->security->ctx_sid;
117 pol_sid = xp->security->ctx_sid; 127 pol_sid = xp->security->ctx_sid;
118 else 128 } else
119 pol_sid = SECINITSID_UNLABELED; 129 if (x->security)
130 /* unlabeled policy and labeled SA can't match */
131 return 0;
132 else
133 /* unlabeled policy and unlabeled SA match all flows */
134 return 1;
120 135
121 err = avc_has_perm(state_sid, pol_sid, SECCLASS_ASSOCIATION, 136 err = avc_has_perm(state_sid, pol_sid, SECCLASS_ASSOCIATION,
122 ASSOCIATION__POLMATCH, 137 ASSOCIATION__POLMATCH,
@@ -125,7 +140,11 @@ int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *
125 if (err) 140 if (err)
126 return 0; 141 return 0;
127 142
128 return selinux_xfrm_flow_state_match(fl, x); 143 err = avc_has_perm(fl->secid, state_sid, SECCLASS_ASSOCIATION,
144 ASSOCIATION__SENDTO,
145 NULL)? 0:1;
146
147 return err;
129} 148}
130 149
131/* 150/*
@@ -133,12 +152,22 @@ int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *
133 * can use a given security association. 152 * can use a given security association.
134 */ 153 */
135 154
136int selinux_xfrm_flow_state_match(struct flowi *fl, struct xfrm_state *xfrm) 155int selinux_xfrm_flow_state_match(struct flowi *fl, struct xfrm_state *xfrm,
156 struct xfrm_policy *xp)
137{ 157{
138 int rc = 0; 158 int rc = 0;
139 u32 sel_sid = SECINITSID_UNLABELED; 159 u32 sel_sid = SECINITSID_UNLABELED;
140 struct xfrm_sec_ctx *ctx; 160 struct xfrm_sec_ctx *ctx;
141 161
162 if (!xp->security)
163 if (!xfrm->security)
164 return 1;
165 else
166 return 0;
167 else
168 if (!xfrm->security)
169 return 0;
170
142 /* Context sid is either set to label or ANY_ASSOC */ 171 /* Context sid is either set to label or ANY_ASSOC */
143 if ((ctx = xfrm->security)) { 172 if ((ctx = xfrm->security)) {
144 if (!selinux_authorizable_ctx(ctx)) 173 if (!selinux_authorizable_ctx(ctx))