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authorTrent Jaeger <tjaeger@cse.psu.edu>2005-12-14 02:12:27 -0500
committerDavid S. Miller <davem@sunset.davemloft.net>2006-01-03 16:10:24 -0500
commitdf71837d5024e2524cd51c93621e558aa7dd9f3f (patch)
tree58938f1d46f3c6713b63e5a785e82fdbb10121a1 /net/core
parent88026842b0a760145aa71d69e74fbc9ec118ca44 (diff)
[LSM-IPSec]: Security association restriction.
This patch series implements per packet access control via the extension of the Linux Security Modules (LSM) interface by hooks in the XFRM and pfkey subsystems that leverage IPSec security associations to label packets. Extensions to the SELinux LSM are included that leverage the patch for this purpose. This patch implements the changes necessary to the XFRM subsystem, pfkey interface, ipv4/ipv6, and xfrm_user interface to restrict a socket to use only authorized security associations (or no security association) to send/receive network packets. Patch purpose: The patch is designed to enable access control per packets based on the strongly authenticated IPSec security association. Such access controls augment the existing ones based on network interface and IP address. The former are very coarse-grained, and the latter can be spoofed. By using IPSec, the system can control access to remote hosts based on cryptographic keys generated using the IPSec mechanism. This enables access control on a per-machine basis or per-application if the remote machine is running the same mechanism and trusted to enforce the access control policy. Patch design approach: The overall approach is that policy (xfrm_policy) entries set by user-level programs (e.g., setkey for ipsec-tools) are extended with a security context that is used at policy selection time in the XFRM subsystem to restrict the sockets that can send/receive packets via security associations (xfrm_states) that are built from those policies. A presentation available at www.selinux-symposium.org/2005/presentations/session2/2-3-jaeger.pdf from the SELinux symposium describes the overall approach. Patch implementation details: On output, the policy retrieved (via xfrm_policy_lookup or xfrm_sk_policy_lookup) must be authorized for the security context of the socket and the same security context is required for resultant security association (retrieved or negotiated via racoon in ipsec-tools). This is enforced in xfrm_state_find. On input, the policy retrieved must also be authorized for the socket (at __xfrm_policy_check), and the security context of the policy must also match the security association being used. The patch has virtually no impact on packets that do not use IPSec. The existing Netfilter (outgoing) and LSM rcv_skb hooks are used as before. Also, if IPSec is used without security contexts, the impact is minimal. The LSM must allow such policies to be selected for the combination of socket and remote machine, but subsequent IPSec processing proceeds as in the original case. Testing: The pfkey interface is tested using the ipsec-tools. ipsec-tools have been modified (a separate ipsec-tools patch is available for version 0.5) that supports assignment of xfrm_policy entries and security associations with security contexts via setkey and the negotiation using the security contexts via racoon. The xfrm_user interface is tested via ad hoc programs that set security contexts. These programs are also available from me, and contain programs for setting, getting, and deleting policy for testing this interface. Testing of sa functions was done by tracing kernel behavior. Signed-off-by: Trent Jaeger <tjaeger@cse.psu.edu> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/flow.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/net/core/flow.c b/net/core/flow.c
index 7e95b39de9fd..c4f25385029f 100644
--- a/net/core/flow.c
+++ b/net/core/flow.c
@@ -23,6 +23,7 @@
23#include <net/flow.h> 23#include <net/flow.h>
24#include <asm/atomic.h> 24#include <asm/atomic.h>
25#include <asm/semaphore.h> 25#include <asm/semaphore.h>
26#include <linux/security.h>
26 27
27struct flow_cache_entry { 28struct flow_cache_entry {
28 struct flow_cache_entry *next; 29 struct flow_cache_entry *next;
@@ -30,6 +31,7 @@ struct flow_cache_entry {
30 u8 dir; 31 u8 dir;
31 struct flowi key; 32 struct flowi key;
32 u32 genid; 33 u32 genid;
34 u32 sk_sid;
33 void *object; 35 void *object;
34 atomic_t *object_ref; 36 atomic_t *object_ref;
35}; 37};
@@ -162,7 +164,7 @@ static int flow_key_compare(struct flowi *key1, struct flowi *key2)
162 return 0; 164 return 0;
163} 165}
164 166
165void *flow_cache_lookup(struct flowi *key, u16 family, u8 dir, 167void *flow_cache_lookup(struct flowi *key, u32 sk_sid, u16 family, u8 dir,
166 flow_resolve_t resolver) 168 flow_resolve_t resolver)
167{ 169{
168 struct flow_cache_entry *fle, **head; 170 struct flow_cache_entry *fle, **head;
@@ -186,6 +188,7 @@ void *flow_cache_lookup(struct flowi *key, u16 family, u8 dir,
186 for (fle = *head; fle; fle = fle->next) { 188 for (fle = *head; fle; fle = fle->next) {
187 if (fle->family == family && 189 if (fle->family == family &&
188 fle->dir == dir && 190 fle->dir == dir &&
191 fle->sk_sid == sk_sid &&
189 flow_key_compare(key, &fle->key) == 0) { 192 flow_key_compare(key, &fle->key) == 0) {
190 if (fle->genid == atomic_read(&flow_cache_genid)) { 193 if (fle->genid == atomic_read(&flow_cache_genid)) {
191 void *ret = fle->object; 194 void *ret = fle->object;
@@ -210,6 +213,7 @@ void *flow_cache_lookup(struct flowi *key, u16 family, u8 dir,
210 *head = fle; 213 *head = fle;
211 fle->family = family; 214 fle->family = family;
212 fle->dir = dir; 215 fle->dir = dir;
216 fle->sk_sid = sk_sid;
213 memcpy(&fle->key, key, sizeof(*key)); 217 memcpy(&fle->key, key, sizeof(*key));
214 fle->object = NULL; 218 fle->object = NULL;
215 flow_count(cpu)++; 219 flow_count(cpu)++;
@@ -221,7 +225,7 @@ nocache:
221 void *obj; 225 void *obj;
222 atomic_t *obj_ref; 226 atomic_t *obj_ref;
223 227
224 resolver(key, family, dir, &obj, &obj_ref); 228 resolver(key, sk_sid, family, dir, &obj, &obj_ref);
225 229
226 if (fle) { 230 if (fle) {
227 fle->genid = atomic_read(&flow_cache_genid); 231 fle->genid = atomic_read(&flow_cache_genid);