From df71837d5024e2524cd51c93621e558aa7dd9f3f Mon Sep 17 00:00:00 2001 From: Trent Jaeger Date: Tue, 13 Dec 2005 23:12:27 -0800 Subject: [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 Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- include/linux/pfkeyv2.h | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'include/linux/pfkeyv2.h') diff --git a/include/linux/pfkeyv2.h b/include/linux/pfkeyv2.h index 724066778aff..6351c4055ace 100644 --- a/include/linux/pfkeyv2.h +++ b/include/linux/pfkeyv2.h @@ -216,6 +216,16 @@ struct sadb_x_nat_t_port { } __attribute__((packed)); /* sizeof(struct sadb_x_nat_t_port) == 8 */ +/* Generic LSM security context */ +struct sadb_x_sec_ctx { + uint16_t sadb_x_sec_len; + uint16_t sadb_x_sec_exttype; + uint8_t sadb_x_ctx_alg; /* LSMs: e.g., selinux == 1 */ + uint8_t sadb_x_ctx_doi; + uint16_t sadb_x_ctx_len; +} __attribute__((packed)); +/* sizeof(struct sadb_sec_ctx) = 8 */ + /* Message types */ #define SADB_RESERVED 0 #define SADB_GETSPI 1 @@ -325,7 +335,8 @@ struct sadb_x_nat_t_port { #define SADB_X_EXT_NAT_T_SPORT 21 #define SADB_X_EXT_NAT_T_DPORT 22 #define SADB_X_EXT_NAT_T_OA 23 -#define SADB_EXT_MAX 23 +#define SADB_X_EXT_SEC_CTX 24 +#define SADB_EXT_MAX 24 /* Identity Extension values */ #define SADB_IDENTTYPE_RESERVED 0 -- cgit v1.2.2