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authorTrent Jaeger <tjaeger@cse.psu.edu>2005-12-14 02:12:40 -0500
committerDavid S. Miller <davem@sunset.davemloft.net>2006-01-03 16:10:25 -0500
commitd28d1e080132f28ab773291f10ad6acca4c8bba2 (patch)
tree4cc6abef076393bc4c9f0d4e4c9952b78c04d3ee /security/selinux/hooks.c
parentdf71837d5024e2524cd51c93621e558aa7dd9f3f (diff)
[LSM-IPSec]: Per-packet access control.
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 SELinux LSM to create, deallocate, and use security contexts for policies (xfrm_policy) and security associations (xfrm_state) that enable control of a socket's ability to send and receive packets. Patch purpose: The patch is designed to enable the SELinux LSM to implement access control on individual packets based on the strongly authenticated IPSec security association. Such access controls augment the existing ones in SELinux based on network interface and IP address. The former are very coarse-grained, and the latter can be spoofed. By using IPSec, the SELinux 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 patch's main function is to authorize a socket's access to a IPSec policy based on their security contexts. Since the communication is implemented by a security association, the patch ensures that the security association's negotiated and used have the same security context. The patch enables allocation and deallocation of such security contexts for policies and security associations. It also enables copying of the security context when policies are cloned. Lastly, the patch ensures that packets that are sent without using a IPSec security assocation with a security context are allowed to be sent in that manner. 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: The function which authorizes a socket to perform a requested operation (send/receive) on a IPSec policy (xfrm_policy) is selinux_xfrm_policy_lookup. The Netfilter and rcv_skb hooks ensure that if a IPSec SA with a securit y association has not been used, then the socket is allowed to send or receive the packet, respectively. The patch implements SELinux function for allocating security contexts when policies (xfrm_policy) are created via the pfkey or xfrm_user interfaces via selinux_xfrm_policy_alloc. When a security association is built, SELinux allocates the security context designated by the XFRM subsystem which is based on that of the authorized policy via selinux_xfrm_state_alloc. When a xfrm_policy is cloned, the security context of that policy, if any, is copied to the clone via selinux_xfrm_policy_clone. When a xfrm_policy or xfrm_state is freed, its security context, if any is also freed at selinux_xfrm_policy_free or selinux_xfrm_state_free. Testing: The SELinux authorization function is tested using ipsec-tools. We created policies and security associations with particular security contexts and added SELinux access control policy entries to verify the authorization decision. We also made sure that packets for which no security context was supplied (which either did or did not use security associations) were authorized using an unlabelled context. 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 'security/selinux/hooks.c')
-rw-r--r--security/selinux/hooks.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index fc774436a264..3d496eae1b47 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -73,6 +73,7 @@
73#include "avc.h" 73#include "avc.h"
74#include "objsec.h" 74#include "objsec.h"
75#include "netif.h" 75#include "netif.h"
76#include "xfrm.h"
76 77
77#define XATTR_SELINUX_SUFFIX "selinux" 78#define XATTR_SELINUX_SUFFIX "selinux"
78#define XATTR_NAME_SELINUX XATTR_SECURITY_PREFIX XATTR_SELINUX_SUFFIX 79#define XATTR_NAME_SELINUX XATTR_SECURITY_PREFIX XATTR_SELINUX_SUFFIX
@@ -3349,6 +3350,10 @@ static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
3349 err = avc_has_perm(sock_sid, port_sid, 3350 err = avc_has_perm(sock_sid, port_sid,
3350 sock_class, recv_perm, &ad); 3351 sock_class, recv_perm, &ad);
3351 } 3352 }
3353
3354 if (!err)
3355 err = selinux_xfrm_sock_rcv_skb(sock_sid, skb);
3356
3352out: 3357out:
3353 return err; 3358 return err;
3354} 3359}
@@ -3401,6 +3406,24 @@ static void selinux_sk_free_security(struct sock *sk)
3401 sk_free_security(sk); 3406 sk_free_security(sk);
3402} 3407}
3403 3408
3409static unsigned int selinux_sk_getsid_security(struct sock *sk, struct flowi *fl, u8 dir)
3410{
3411 struct inode_security_struct *isec;
3412 u32 sock_sid = SECINITSID_ANY_SOCKET;
3413
3414 if (!sk)
3415 return selinux_no_sk_sid(fl);
3416
3417 read_lock_bh(&sk->sk_callback_lock);
3418 isec = get_sock_isec(sk);
3419
3420 if (isec)
3421 sock_sid = isec->sid;
3422
3423 read_unlock_bh(&sk->sk_callback_lock);
3424 return sock_sid;
3425}
3426
3404static int selinux_nlmsg_perm(struct sock *sk, struct sk_buff *skb) 3427static int selinux_nlmsg_perm(struct sock *sk, struct sk_buff *skb)
3405{ 3428{
3406 int err = 0; 3429 int err = 0;
@@ -3536,6 +3559,11 @@ static unsigned int selinux_ip_postroute_last(unsigned int hooknum,
3536 send_perm, &ad) ? NF_DROP : NF_ACCEPT; 3559 send_perm, &ad) ? NF_DROP : NF_ACCEPT;
3537 } 3560 }
3538 3561
3562 if (err != NF_ACCEPT)
3563 goto out;
3564
3565 err = selinux_xfrm_postroute_last(isec->sid, skb);
3566
3539out: 3567out:
3540 return err; 3568 return err;
3541} 3569}
@@ -4380,6 +4408,16 @@ static struct security_operations selinux_ops = {
4380 .socket_getpeersec = selinux_socket_getpeersec, 4408 .socket_getpeersec = selinux_socket_getpeersec,
4381 .sk_alloc_security = selinux_sk_alloc_security, 4409 .sk_alloc_security = selinux_sk_alloc_security,
4382 .sk_free_security = selinux_sk_free_security, 4410 .sk_free_security = selinux_sk_free_security,
4411 .sk_getsid = selinux_sk_getsid_security,
4412#endif
4413
4414#ifdef CONFIG_SECURITY_NETWORK_XFRM
4415 .xfrm_policy_alloc_security = selinux_xfrm_policy_alloc,
4416 .xfrm_policy_clone_security = selinux_xfrm_policy_clone,
4417 .xfrm_policy_free_security = selinux_xfrm_policy_free,
4418 .xfrm_state_alloc_security = selinux_xfrm_state_alloc,
4419 .xfrm_state_free_security = selinux_xfrm_state_free,
4420 .xfrm_policy_lookup = selinux_xfrm_policy_lookup,
4383#endif 4421#endif
4384}; 4422};
4385 4423
@@ -4491,6 +4529,7 @@ static int __init selinux_nf_ip_init(void)
4491 panic("SELinux: nf_register_hook for IPv6: error %d\n", err); 4529 panic("SELinux: nf_register_hook for IPv6: error %d\n", err);
4492 4530
4493#endif /* IPV6 */ 4531#endif /* IPV6 */
4532
4494out: 4533out:
4495 return err; 4534 return err;
4496} 4535}