[PATCH 4/6][v2] audit: add netlink audit protocol bind to check capabilities on multicast join

Richard Guy Briggs
2014-04-23T01:31:56Z

Register a netlink per-protocol bind fuction for audit to check userspace
process capabilities before allowing a multicast group connection.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
---
include/uapi/linux/capability.h | 7 ++++++-
kernel/audit.c | 10 ++++++++++
security/selinux/include/classmap.h | 2 +-
3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h
index 154dd6d..12c37a1 100644
--- a/include/uapi/linux/capability.h
+++ b/include/uapi/linux/capability.h
@@ -347,7 +347,12 @@ struct vfs_cap_data {

#define CAP_BLOCK_SUSPEND 36

-#define CAP_LAST_CAP CAP_BLOCK_SUSPEND
+/* Allow reading the audit log via multicast netlink socket */
+
+#define CAP_AUDIT_READ 37
+
+
+#define CAP_LAST_CAP CAP_AUDIT_READ

#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)

diff --git a/kernel/audit.c b/kernel/audit.c
index 7c28936..223cb74 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1076,10 +1076,20 @@ static void audit_receive(struct sk_buff *skb)
mutex_unlock(&audit_cmd_mutex);
}

+/* Run custom bind function on netlink socket group connect or bind requests. */
+static int audit_bind(int group)
+{
+ if (!capable(CAP_AUDIT_READ))
+ return -EPERM;
+
+ return 0;
+}
+
static int __net_init audit_net_init(struct net *net)
{
struct netlink_kernel_cfg cfg = {
.input = audit_receive,
+ .bind = audit_bind,
};

struct audit_net *aunet = net_generic(net, audit_net_id);
diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
index 14d04e6..be491a7 100644
--- a/security/selinux/include/classmap.h
+++ b/security/selinux/include/classmap.h
@@ -147,7 +147,7 @@ struct security_class_mapping secclass_map[] = {
{ "peer", { "recv", NULL } },
{ "capability2",
{ "mac_override", "mac_admin", "syslog", "wake_alarm", "block_suspend",
- NULL } },
+ "audit_read", NULL } },
{ "kernel_service", { "use_as_override", "create_files_as", NULL } },
{ "tun_socket",
{ COMMON_SOCK_PERMS, "attach_queue", NULL } },
--
1.7.1